95916 Federal Register / Vol. 89, No. 232 / Tuesday, December 3, 2024 / Notices 

1Traffic Safety Facts 2021 ‘‘A Compilation of 

Motor Vehicle Crash Data.’’ U.S. Department of 

Transportation. National Highway Traffic Safety 

Administration. NHTSA acknowledges a recent 

increase in passenger vehicle occupant fatalities 

occurring during the COVID–19 pandemic. In 2019, 

22,372 passenger vehicle occupants were killed in 

traffic crashes. 

2Traffic Safety Facts 2021 ‘‘A Compilation of 

Motor Vehicle Crash Data.’’ U.S. Department of 

Transportation. National Highway Traffic Safety 

Administration. 

3 Docket No. NHTSA–2021–0002. 87 FR 13452 

(March 9, 2022). 

4The ADAS technologies currently evaluated in 

NCAP are forward collision warning (FCW), lane 

departure warning (LDW), dynamic brake support 

(DBS), and crash imminent braking (CIB). 

5 ‘‘LKS’’ was used for this technology in the 

March 2022 RFC. However, in this final decision 

notice, ‘‘LKA’’ is used instead to maintain 

consistency with other agency initiatives. 

6Public Law 114–94. 

7Public Law 117–58. 

8 Docket No. NHTSA–2023–0021. 89 FR 39686 

(May. 9, 2024). 

9Section 24322 of the FAST Act, otherwise 

known as the ‘‘Safety Through Informed Consumers 

Act of 2015.’’ 

10Public Law 117–58. 

11 Id. at Section 24213(a); the notice referred to in 

the Bipartisan Infrastructure Law is 80 FR 78522 

(Dec. 16, 2015). 

12 Docket No. NHTSA–2015–0119. 80 FR 78591 

(Dec. 16, 2015). 

13As communicated in the March 2022 RFC, 

while NHTSA is adopting a roadmap that includes 

aspects of the 2015 RFC, this notice is not an 

extension of the December 2015 notice. 

DEPARTMENT OF TRANSPORTATION 

National Highway Traffic Safety 

Administration 

[Docket No. NHTSA–2024–0077] 

New Car Assessment Program Final 

Decision Notice—Advanced Driver 

Assistance Systems and Roadmap 

AGENCY: National Highway Traffic 

Safety Administration (NHTSA or the 

Agency), Department of Transportation 

(DOT). 

ACTION: Final decision notice. 

SUMMARY: This final decision notice 

adds four new advanced driver 

assistance systems (ADAS) 

technologies—blind spot warning 

(BSW), blind spot intervention (BSI), 

lane keeping assist (LKA), and 

pedestrian automatic emergency braking 

(PAEB)—to the New Car Assessment 

Program (NCAP) and enhances the 

performance evaluation of ADAS 

technologies currently in NCAP. The 

notice also finalizes a 10-year roadmap 

for updating NCAP through multiple 

phases for the period 2024 through 

2033. This notice responds in part to the 

provisions in section 24213 of the 

Infrastructure, Investment, and Jobs Act. 

DATES: Decisions on planned changes to 

the New Car Assessment Program are 

effective for the 2026 model year. 

FOR FURTHER INFORMATION CONTACT: For 

technical issues, you may contact Ms. 

Taryn E. Rockwell, New Car Assessment 

Program, Office of Crashworthiness 

Standards (Telephone: (202) 366–1810). 

For legal issues, you may contact Ms. 

Sara R. Bennett, or Ms. Natasha D. Reed, 

Office of Chief Counsel (Telephone: 

(202) 366–2992). You may send mail to 

these officials at the National Highway 

Traffic Safety Administration, 1200 New 

Jersey Avenue SE, West Building, 

Washington, DC 20590–0001. 

SUPPLEMENTARY INFORMATION: 

Table of Contents 

I. Executive Summary 

II. Summary of Updates to NCAP and 

Roadmap for Future Updates 

III. Background 

IV. Updating Forward Collision Prevention 

Technologies 

V. Adding Pedestrian Automatic Emergency 

Braking (PAEB) Technology 

VI. Adding Blind Spot Technologies 

VII. Updating Lane Keeping Technologies 

VIII. Self-Reported Data 

IX. NCAP Roadmap 

X. Economic Analysis 

XI. Appendix 

I. Executive Summary 

Since its launch in 1978, NHTSA’s 

New Car Assessment Program (NCAP) 

has supported NHTSA’s mission to 

reduce the number of fatalities and 

injuries that occur on U.S. roadways. 

NCAP, like many other NHTSA 

programs, has contributed to significant 

reductions in motor vehicle related 

crashes, fatalities, and injuries, with 

passenger vehicle occupant fatalities 

decreasing from 32,043 to 26,325 from 

2001 to 2021.1 Unfortunately, this 

reduction was not universal, with 

pedestrian fatalities increasing by 51 

percent during the same timeframe, 

from 4,901 to 7,388.2 Despite 

improvements in automotive safety 

since NCAP’s implementation, far more 

work must be done to reduce the 

continued high toll to human life on our 

nation’s roads. In response to this need, 

on March 9, 2022, NHTSA published a 

Request for Comments (RFC) notice 

outlining proposed NCAP updates.3

After careful consideration of all 

comments received and applicable 

regulatory considerations, this notice 

announces the Agency’s decision to 

update NCAP with the enhanced 

evaluation of advanced driver assistance 

systems (ADAS) technologies currently 

in NCAP 4 and to add four new ADAS 

technologies to NCAP: blind spot 

warning (BSW), blind spot intervention 

(BSI), lane keeping assist (LKA),5 and 

pedestrian automatic emergency braking 

(PAEB). This notice also establishes a 

10-year roadmap for updating NCAP 

through a multi-phased approach, with 

RFC notices planned over the next 

several years. NHTSA will address 

comments received on program 

elements outside the scope of the March 

2022 RFC notice in subsequent final 

decision notices as part of the multiphase efforts to update NCAP over the 

next several years. 

A. Legal and Policy Considerations 

In finalizing its decisions for this 

notice, in addition to comments 

received, the Agency sought to address 

requirements from the 2015 Fixing 

America’s Surface Transportation 

(FAST) Act,6 the 2021 Bipartisan 

Infrastructure Law (BIL), enacted as the 

Infrastructure Investment and Jobs Act,7

and the U.S. Department of 

Transportation’s National Roadway 

Safety Strategy. The Agency also took 

into consideration its May 9, 2024, final 

rule for FMVSS No. 127, ‘‘Automatic 

Emergency Braking for Light 

Vehicles.’’ 8 These considerations are 

described below. 

1. 2015 Fixing America’s Surface 

Transportation Act 

This final decision notice serves as 

NHTSA’s initial step in fulfilling section 

24322 of the FAST Act, which directs 

the Agency to promulgate a rule 

ensuring the display of crash avoidance 

information next to crashworthiness 

information on window stickers that 

manufacturers place on motor vehicles.9

The Agency is currently working to 

develop a crash avoidance rating system 

based on comments received in 

response to several rating system 

concepts discussed in the March 2022 

RFC, and this notice finalizes additional 

crash avoidance technologies that will 

be included in the future crash 

avoidance rating system. 

2. 2021 Bipartisan Infrastructure Law 

This notice also fulfills in part several 

mandates in section 24213 of the BIL, 

enacted on November 15, 2021 as the 

Infrastructure Investment and Jobs 

Act.10 First, section 24213(a) requires 

NHTSA to ‘‘finalize the proceeding for 

which comments were requested’’ on 

December 16, 2015.11 This final 

decision notice does so by adopting four 

new ADAS technologies discussed in 

the Agency’s December 16, 2015 RFC 

notice,12 thus finalizing that proceeding 

and notice.13

Second, this notice addresses the 

Advanced Crash-Avoidance 

Technologies portion of section 

24213(b) of the BIL, which directs the 

Secretary of the Department of 


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Federal Register / Vol. 89, No. 232 / Tuesday, December 3, 2024 / Notices 95917 

14This notice refers to advanced crash avoidance 

technology as ADAS technology. 

15U.S. Department of Transportation. (2020). 

‘‘National Roadway Safety Strategy, Version 1.1.’’ 

https://www.transportation.gov/sites/dot.gov/files/ 

2022-02/USDOT-National-Roadway-SafetyStrategy.pdf. 

16https://www.transportation.gov/NRSS/ 

SafeSystem. 

17 Vehicles produced by small-volume 

manufacturers, final-stage manufacturers, and 

alterers must be equipped with a compliant AEB 

system by September 1, 2030. 

Transportation to ‘‘publish a notice, for 

the purposes of public comment, to 

establish a means for providing 

consumer information relating to 

advanced crash-avoidance 

technologies’’ within one year of 

enactment that includes an appropriate 

methodology for: (1) determining which 

advanced crash avoidance technologies 

should be included in the information, 

(2) developing performance test criteria 

for use by manufacturers in evaluating 

those technologies, (3) determining a 

distinct rating system involving each 

crash avoidance technology, and (4) 

updating overall vehicle ratings to 

incorporate the advanced crash 

avoidance technology ratings. This 

notice satisfies two of these four 

requirements by (1) adopting 

established criteria for determining 

which advanced crash avoidance 

technology 14 should be included as 

referenced and discussed in the March 

9, 2022 RFC notice, and (2) finalizing 

test procedures and criteria to evaluate 

performance for each of these advanced 

crash avoidance technologies. Although 

the Agency is not yet implementing a 

rating system for individual crash 

avoidance technologies, it has sought 

comments in this regard and has 

detailed plans in its roadmap to finalize 

such ratings, along with an updated 

overall (i.e., crashworthiness and crash 

avoidance) rating, in the near future. 

Third, this notice addresses the 

Vulnerable Road User Safety portion of 

section 24213(b), which directs the 

Secretary to publish a notice meeting 

similar requirements to those mandated 

for advanced crash avoidance 

technologies ‘‘to establish a means for 

providing to consumers information 

relating to pedestrian, bicyclist, or other 

vulnerable road user safety 

technologies’’ within one year of 

enactment. By applying the established 

inclusion criteria in the adoption of 

PAEB technology and the applicable test 

procedures and evaluation criteria 

included in this notice, two of the four 

requirements for the Vulnerable Road 

User Safety portion of section 24213(b) 

will be met. NHTSA will fulfill the 

remaining requirements when it 

proposes and finalizes a new rating 

system for the crash avoidance 

technologies in NCAP. 

Fourth, this final decision notice 

fulfills the requirements in section 

24213(c) of the BIL. This section states 

that, within one year of the law’s 

enactment, the Secretary of the 

Department of Transportation shall 

establish a roadmap, vetted through the 

public comment process, identifying 

and prioritizing safety opportunities and 

technologies that could be used in 

future roadmaps, establishing a plan for 

implementation of NCAP changes, and 

considering the benefits of consistency 

with other U.S. and international rating 

systems. Section 24213(c) further 

specifies that the roadmap shall span a 

term of ten years, with five-year midterm and five-year long-term 

components. Further, it requires 

updates to the roadmap at least once 

every four years to reflect new Agency 

interests and diverse stakeholder input 

(garnered annually), and in 

consideration of opportunities to benefit 

from collaboration and/or 

harmonization with third-party safety 

rating programs. As will be discussed 

herein, the Agency is taking steps to 

harmonize with existing consumer 

information rating programs, where 

possible and when appropriate, both for 

this NCAP update and future initiatives 

included in the program’s roadmap. The 

Agency’s proposed roadmap includes 

phased updates, as mandated, and was 

made available for public comment as 

part of the March 2022 RFC notice. As 

all relevant comments received have 

been considered prior to this notice’s 

finalization, the Agency has fulfilled the 

requirements of section 24213(c). 

Additional details for the mid-term and 

long-term five-year spans are available 

in the NCAP Roadmap section of this 

notice. 

3. 2022 U.S. Department of 

Transportation National Roadway 

Safety Strategy (NRSS) 

The U.S. Department of 

Transportation published the National 

Roadway Safety Strategy (NRSS) in 

January 2022.15 The NRSS announced 

key planned departmental actions 

aimed at significantly reducing serious 

roadway injuries and deaths to reach the 

Department’s long-term zero roadway 

fatalities goal. At the core of the NRSS 

is the Department-wide adoption of the 

Safe Systems Approach,16 which 

focuses on building layers of protection 

to both prevent crashes from happening 

and minimize harm when crashes do 

occur. 

With respect to NCAP, the NRSS 

supports program updates emphasizing 

safety features that protect people both 

inside and outside the vehicle. These 

safety features may incorporate 

consideration of pedestrian protection 

systems, better understanding of 

impacts to pedestrians (e.g., specific 

considerations for children), and may 

include automatic emergency braking 

and lane keeping assistance to benefit 

bicyclists and pedestrians. The NCAP 

program also works to identify the most 

promising vehicle technologies to help 

achieve NRSS’s safety goals, such as 

alcohol detection systems and driver 

distraction mitigation systems. In 

addition, the NRSS includes a 10-year 

roadmap for the program and lists as a 

key departmental action the initiation of 

rulemaking to update the vehicle 

Monroney label. As part of that process, 

the Agency may also consider including 

information on features that mitigate 

safety risks for people outside of the 

vehicle. 

This final decision notice presents 

NHTSA’s initial actions towards the 

implementation of this broad, multifaceted safety strategy for NCAP that 

includes improved road safety for both 

motor vehicle occupants and people 

outside of the vehicle, including 

pedestrians and other vulnerable road 

users. Additionally, the 10-year 

roadmap for the program presents a plan 

for the incorporation of future safety 

technologies and provides a projected 

timeline for updating the Monroney 

label to include crash avoidance 

information. 

Relatedly, NRSS lists the initiation of 

a new rulemaking to require automatic 

emergency braking and pedestrian 

automatic emergency braking on 

passenger vehicles as a key 

departmental action. In response to this 

action, NHTSA published a final rule on 

May 9, 2024, establishing a new Federal 

motor vehicle safety standard, FMVSS 

No. 127, ‘‘Automatic Emergency Braking 

for Light Vehicles.’’ Similar to the 

changes adopted by NCAP in this 

notice, this final rule aims to reduce the 

frequency and associated injury and 

fatalities of rear-end and pedestrian 

crashes. Manufacturers must comply 

with the final rule by September 1, 

2029.17 This final decision notice will 

upgrade NCAP to provide consumers 

with additional vehicle safety 

information on AEB and PAEB 

technologies to help them make more 

informed purchasing decisions. NHTSA 

will identify vehicles that are equipped 

with these recommended technologies 

and pass NHTSA’s performance criteria 

by way of check marks on the NHTSA 

website starting with model year 2026 


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18See Appendix. 

19CIB and DBS systems are collectively known as 

automatic emergency braking (AEB). 

20Trial or test trial is a test among a set of tests 

conducted under the same test conditions 

(including test speed) with the same subject 

vehicle. 

21 In essence, because the Agency will provide an 

overall assessment for AEB performance, if a 

vehicle fails a trial run in the DBS test, testing will 

cease for the DBS assessment, and CIB assessments 

will not be conducted because the vehicle will have 

failed the AEB assessment overall. 

22For purposes of this document, NHTSA uses 

‘‘false positive’’ and ‘‘false activation’’ 

interchangeably, and the Agency intends for them 

to refer to the same situations. 

vehicles, as discussed in the following 

sections. Although the final rule and 

this decision on NCAP rely on the 

agency’s separate authorities, NHTSA 

has sought to ensure that the revised test 

procedures for NCAP and the AEB final 

rule are compatible with one another, 

such that a manufacturer would be able 

to design a system that both received 

NCAP credit and would meet the 

requirements contained in the final 

rule.18 NHTSA believes these collective 

efforts will lead to more rapid and 

complete market penetration of AEB 

and PAEB technologies. 

II. Summary of Updates to NCAP and 

Roadmap for Future Updates 

A brief summary of the updates to 

NCAP included in this final decision 

notice is provided below, along with the 

finalized 10-year roadmap for future 

updates to NCAP. 

Updates To Crash Imminent Braking 

(CIB), Dynamic Brake Support (DBS), 

and Forward Collision Warning (FCW) 

Evaluations 

This notice modifies the existing test 

conditions, evaluation procedure, and 

performance criteria for crash imminent 

braking (CIB) and dynamic brake 

support (DBS) systems, subject to the 

same test scenarios currently used in 

NCAP.19 An overview of the amended 

test scenarios (Lead Vehicle Stopped 

(LVS), Lead Vehicle Moving (LVM), and 

Lead Vehicle Decelerating (LVD)) and 

test conditions (subject vehicle (SV) 

speed, principal other vehicle (POV) 

speed, POV headway, and POV 

deceleration) required to receive passing 

credit for AEB systems (i.e., CIB and 

DBS collectively) in NCAP is shown in 

Tables 1 and 2. NHTSA will test 

vehicles starting with the lowest test 

speed for a test scenario and 

incrementally increase test speed 

according to the test matrix in Tables 1 

and 2, with only one trial 20 conducted 

per test condition. The passing criterion 

for a test trial is no contact between the 

subject vehicle and principal other 

vehicle. If the subject vehicle contacts 

the principal other vehicle during a test 

trial, the vehicle fails the assessed test 

condition and the AEB test overall, 

whether CIB or DBS. In the event of 

subject vehicle-to-principal other 

vehicle contact, testing will cease for the 

test condition, respective test scenario, 

the AEB test being performed (i.e., CIB 

or DBS), and the AEB assessment 

overall.21 NHTSA will also continue to 

conduct the false positive 22 test 

scenario currently used in NCAP, but 

has modified the test conditions and 

requirements for passing performance. 

This test scenario evaluates the 

propensity of a vehicle’s DBS system to 

activate inappropriately in a non-critical 

driving scenario that would not present 

a safety risk to the vehicle’s occupants. 

A vehicle must pass each of the 19 

required CIB test conditions to obtain 

credit for CIB and must also separately 

pass each of the 17 required DBS test 

conditions to obtain credit for DBS. 

NHTSA is consolidating forward 

collision warning (FCW) testing to 

assess and evaluate FCW functionality 

during CIB and DBS testing in all test 

scenarios except NHTSA’s false positive 

tests. For evaluations during CIB and 

DBS testing, the test vehicle must issue 

an FCW prior to the onset of automatic 

braking (as defined by the instant the 

subject vehicle deceleration reaches at 

least 0.15g) for the vehicle to pass each 

test trial run conducted as part of 

NCAP’s CIB and DBS testing. If the 

required FCW is not issued prior to the 

onset of automatic braking imparted by 

CIB, the vehicle will fail the test trial 

and CIB/DBS assessment overall. 

NHTSA will conduct the AEB 

evaluation by (1) fully releasing the 

subject vehicle’s accelerator pedal (at 

any rate) within 500 milliseconds (ms) 

after an FCW is issued (during CIB and 

DBS evaluations, and whether before or 

after automatic braking has begun), and 

(2) initiating manual (robotic) brake 

application at a time that corresponds to 

1.0 ± 0.1 seconds after issuance of the 

required FCW signals (during DBS 

evaluations). A FCW must be presented 

to the vehicle operator via a minimum 

of two sensory modalities to receive 

credit in each of NCAP’s CIB and DBS 

tests (except for the false positive test). 

A vehicle must present, at a minimum, 

an FCW comprised of visual and 

auditory signals. Finally, Revision G of 

the AB Dynamics (ABD) Global Vehicle 

Target (GVT) will be used as the 

principal other vehicle in NCAP testing 

instead of the currently used Strikable 

Surrogate Vehicle (SSV) test device. 

Other details of the test conditions and 

response to comments on updating CIB, 

DBS, and FCW evaluations are provided 

in relevant sections in this notice. 

TABLE 1—ADOPTED CIB TEST SCENARIOS AND CONDITIONS

Test no. Test scenario SV speed (kph 

(mph)) 

POV speed 

(kph (mph)) 

POV headway 

(m (ft.)) 

POV 

deceleration 

(g) 

Requirement to pass 

1 ................ LVS 40 (24.9) 0 n/a n/a No SV-to-POV contact during any test trial. 

2 ................ 50 (31.1) 0 n/a n/a 

3 ................ 60 (37.3) 0 n/a n/a 

4 ................ 70 (43.5) 0 n/a n/a 

5 ................ 80 (49.7) 0 n/a n/a 

6 ................ LVM 40 (24.9) 20 (12.4) n/a n/a 

7 ................ 50 (31.1) 20 (12.4) n/a n/a 

8 ................ 60 (37.3) 20 (12.4) n/a n/a 

9 ................ 70 (43.5) 20 (12.4) n/a n/a 

10 .............. 80 (49.7) 20 (12.4) n/a n/a 

11 .............. LVD 50 (31.1) 50 (31.1) 40 (131.2) 0.3 

12 .............. 50 (31.1) 50 (31.1) 12 (39.4) 0.3 

13 .............. 80 (49.7) 80 (49.7) 40 (131.2) 0.3 

14 .............. 80 (49.7) 80 (49.7) 12 (39.4) 0.3 

15 .............. 50 (31.1) 50 (31.1) 40 (131.2) 0.5 

16 .............. 50 (31.1) 50 (31.1) 12 (39.4) 0.5 

17 .............. 80 (49.7) 80 (49.7) 40 (131.2) 0.5 


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TABLE 1—ADOPTED CIB TEST SCENARIOS AND CONDITIONS—Continued 

Test no. Test scenario SV speed (kph 

(mph)) 

POV speed 

(kph (mph)) 

POV headway 

(m (ft.)) 

POV 

deceleration 

(g) 

Requirement to pass 

18 .............. 80 (49.7) 80 (49.7) 12 (39.4) 0.5 

19 .............. False Positive 

(STP) 

80 (49.7) n/a n/a n/a SV peak deceleration <0.25g 

TABLE 2—ADOPTED DBS TEST SCENARIOS AND CONDITIONS

Test no. Test scenario SV speed (kph 

(mph)) 

POV speed 

(kph (mph)) 

POV headway 

(m (ft.)) 

POV 

deceleration 

(g) 

Requirement to pass 

1 ................ LVS 70 (43.5) 0 n/a n/a No SV-to-POV contact during any test trial. 

2 ................ 80 (49.7) 0 n/a n/a 

3 ................ 90 (55.9) 0 n/a n/a 

4 ................ 100 (62.1) 0 n/a n/a 

5 ................ LVM 70 (43.5) 20 (12.4) n/a n/a 

6 ................ 80 (49.7) 20 (12.4) n/a n/a 

7 ................ 90 (55.9) 20 (12.4) n/a n/a 

8 ................ 100 (62.1) 20 (12.4) n/a n/a 

9 ................ LVD 50 (31.1) 50 (31.1) 40 (131.2) 0.3 

10 .............. 50 (31.1) 50 (31.1) 12 (39.4) 0.3 

11 .............. 80 (49.7) 80 (49.7) 40 (131.2) 0.3 

12 .............. 80 (49.7) 80 (49.7) 12 (39.4) 0.3 

13 .............. 50 (31.1) 50 (31.1) 40 (131.2) 0.5 

14 .............. 50 (31.1) 50 (31.1) 12 (39.4) 0.5 

15 .............. 80 (49.7) 80 (49.7) 40 (131.2) 0.5 

16 .............. 80 (49.7) 80 (49.7) 12 (39.4) 0.5 

17 .............. False Positive 

(STP) 

80 (49.7) n/a n/a n/a SV peak deceleration <0.25g over the baseline peak imparted by manual braking. 

Adding Pedestrian Automatic 

Emergency Braking Evaluation 

NHTSA is adding the evaluation of 

pedestrian automatic emergency braking 

(PAEB) to NCAP using four crossing test 

scenarios and two in-path test scenarios 

to evaluate PAEB in daylight and 

darkness lighting conditions with no 

overhead lights. For the crossing 

scenarios (S1), a walking adult or 

running child pedestrian mannequin 

crosses perpendicular to the vehicle’s 

line of travel from either the driver’s left 

or right side. For the in-path scenarios 

(S4), an adult pedestrian mannequin is 

slightly overlapped with the front of the 

vehicle and is either facing away while 

standing in front of the vehicle, or 

walking away from the vehicle, parallel 

to the flow of traffic. 

The subject vehicle’s lower beam 

headlamps will be used during all 

NCAP PAEB testing in dark lighting 

conditions, and the upper beam 

headlamps will not be engaged either 

manually or automatically by way of an 

advanced lighting system, such as 

adaptive driving beams, unless such a 

system cannot be deactivated. This 

requirement will apply even to those 

systems that are active by default when 

low beam headlamps are first engaged. 

The performance criterion for NCAP’s 

PAEB tests will be no contact with the 

pedestrian mannequin. The 4activePA 

Adult and 4activePA Child pedestrian 

test mannequins (articulating 

mannequins) will be used for NCAP’s 

PAEB evaluation. 

NHTSA will test for each of the 

adopted PAEB test conditions at a 

minimum subject vehicle speed 

threshold of 10 kph (6.2 mph), 

increasing the subject vehicle speed in 

10 kph (6.2 mph) increments until the 

maximum speed threshold is reached, 

so long as the test vehicle does not 

contact the pedestrian mannequin 

during each progressive speed tested. 

For test conditions S1a, S1b, S1e, S4a, 

and S4c, the Agency is adopting a 

maximum subject vehicle speed 

threshold of 60 kph (37.3 mph) for both 

daylight and darkness testing. For test 

condition S1d, NHTSA is adopting a 

maximum subject vehicle speed 

threshold of 60 kph (37.3 mph) for 

daylight testing and 40 kph (24.9 mph) 

for darkness testing. Should the subject 

vehicle contact the pedestrian 

mannequin during the initial run for 

any test speed, testing will cease for the 

test condition, respective test scenario, 

and PAEB testing overall for the 

particular lighting condition. Only one 

trial will be conducted per test 

condition and vehicles must pass all 

required tests (i.e., no contact with 

pedestrian mannequin) to receive PAEB 

credit for the relevant lighting 

condition. 

An overview of test scenarios and test 

parameters (pedestrian size, test speed, 

pedestrian motion, overlap, and 

obstruction) is provided in Tables 3 and 

4. 

TABLE 3—ADOPTED NCAP PAEB DAYLIGHT TEST CONDITIONS AND VARIANTS

Test condition Size Movement 

classification 

Path 

origin 

Overlap 

(%) Obstruction Test no. 

Test speeds 

(kph (mph)) 

SV Pedestrian 

S4c .......................... Adult (Facing 

Away).

Walk ............ Right ..... 25 ........... No ............. 1 10 (6.2) 5 (3.1) 


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TABLE 3—ADOPTED NCAP PAEB DAYLIGHT TEST CONDITIONS AND VARIANTS—Continued 

Test condition Size Movement 

classification 

Path 

origin 

Overlap 

(%) Obstruction Test no. 

Test speeds 

(kph (mph)) 

SV Pedestrian 

2 20 (12.4) 5 (3.1) 

3 30 (18.6) 5 (3.1) 

4 40 (24.9) 5 (3.1) 

5 50 (31.1) 5 (3.1) 

6 60 (37.3) 5 (3.1) 

S4a .......................... Adult (Facing 

Away).

Stationary ... Right ..... 25 ........... No ............. 7 10 (6.2) 0 

8 20 (12.4) 0 

9 30 (18.6) 0 

10 40 (24.9) 0 

11 50 (31.1) 0 

12 60 (37.3) 0 

S1b .......................... Adult ................ Walk ............ Right ..... 50 ........... No ............. 13 10 (6.2) 5 (3.1) 

14 20 (12.4) 5 (3.1) 

15 30 (18.6) 5 (3.1) 

16 40 (24.9) 5 (3.1) 

17 50 (31.1) 5 (3.1) 

18 60 (37.3) 5 (3.1) 

S1a .......................... Adult ................ Walk ............ Right ..... 25 ........... No ............. 19 10 (6.2) 5 (3.1) 

20 20 (12.4) 5 (3.1) 

21 30 (18.6) 5 (3.1) 

22 40 (24.9) 5 (3.1) 

23 50 (31.1) 5 (3.1) 

24 60 (37.3) 5 (3.1) 

S1e .......................... Adult ................ Run ............. Left ........ 50 ........... No ............. 25 10 (6.2) 8 (5.0) 

26 20 (12.4) 8 (5.0) 

27 30 (18.6) 8 (5.0) 

28 40 (24.9) 8 (5.0) 

29 50 (31.1) 8 (5.0) 

30 60 (37.3) 8 (5.0) 

S1d .......................... Child ................ Run ............. Right ..... 50 ........... Yes ........... 31 10 (6.2) 5 (3.1) 

32 20 (12.4) 5 (3.1) 

33 30 (18.6) 5 (3.1) 

34 40 (24.9) 5 (3.1) 

35 50 (31.1) 5 (3.1) 

36 60 (37.3) 5 (3.1) 

TABLE 4—ADOPTED NCAP PAEB DARKNESS TEST CONDITIONS AND VARIANTS

Test condition Size Movement 

classification 

Path 

origin 

Overlap 

(%) Obstruction Test no. 

Test speeds (kph (mph)) 

SV Pedestrian 

S4c .......................... Adult (Facing 

Away).

Walk ............ Right ..... 25 ........... No ............. 1 10 (6.2) 5 (3.1) 

2 20 (12.4) 5 (3.1) 

3 30 (18.6) 5 (3.1) 

4 40 (24.9) 5 (3.1) 

5 50 (31.1) 5 (3.1) 

6 60 (37.3) 5 (3.1) 

S4a .......................... Adult (Facing 

Away).

Stationary ... Right ..... 25 ........... No ............. 7 10 (6.2) 0 

8 20 (12.4) 0 

9 30 (18.6) 0 

10 40 (24.9) 0 

11 50 (31.1) 0 

12 60 (37.3) 0 

S1b .......................... Adult ................ Walk ............ Right ..... 50% ........ No ............. 13 10 (6.2) 5 (3.1) 

14 20 (12.4) 5 (3.1) 

15 30 (18.6) 5 (3.1) 

16 40 (24.9) 5 (3.1) 

17 50 (31.1) 5 (3.1) 

18 60 (37.3) 5 (3.1) 

S1a .......................... Adult ................ Walk ............ Right ..... 25 ........... No ............. 19 10 (6.2) 5 (3.1) 

20 20 (12.4) 5 (3.1) 

21 30 (18.6) 5 (3.1) 

22 40 (24.9) 5 (3.1) 

23 50 (31.1) 5 (3.1) 

24 60 (37.3) 5 (3.1) 


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Federal Register / Vol. 89, No. 232 / Tuesday, December 3, 2024 / Notices 95921 

23The two scenarios for assessing BSW were 

proposed in the March 2022 RFC notice and are 

described in a later section of this notice. 

TABLE 4—ADOPTED NCAP PAEB DARKNESS TEST CONDITIONS AND VARIANTS—Continued 

Test condition Size Movement 

classification 

Path 

origin 

Overlap 

(%) Obstruction Test no. 

Test speeds (kph (mph)) 

SV Pedestrian 

S1e .......................... Adult ................ Run ............. Left ........ 50 ........... No ............. 25 10 (6.2) 8 (5.0) 

26 20 (12.4) 8 (5.0) 

27 30 (18.6) 8 (5.0) 

28 40 (24.9) 8 (5.0) 

29 50 (31.1) 8 (5.0) 

30 60 (37.3) 8 (5.0) 

S1d .......................... Child ................ Run ............. Right ..... 50 ........... Yes ........... 31 10 (6.2) 5 (3.1) 

32 20 (12.4) 5 (3.1) 

33 30 (18.6) 5 (3.1) 

34 40 (24.9) 5 (3.1) 

* All darkness testing to occur without the use of overhead artificial lighting. 

Adding Blind Spot Warning (BSW) and 

Blind Spot Intervention (BSI) Evaluation 

This notice adds assessments for two 

blind spot technologies, BSW and BSI, 

to NCAP’s crash avoidance program. 

Blind spot warning (BSW) and blind 

spot intervention (BSI) will be evaluated 

separately in individual tests conducted 

in daylight with the principal other 

vehicle on the left and right side of the 

subject vehicle, with the subject vehicle 

turn signal indicator activated and not 

activated. BSW will be evaluated using 

tests representing the Straight Lane 

Converge and Diverge and Straight Lane 

Pass-by scenarios,23 using an actual 

vehicle (representing a high production 

mid-size passenger car) as the principal 

other vehicle. For tests where the turn 

signal is not activated, a visual warning 

signal in the side mirror or the A-pillar 

must be issued within a specified time 

as detailed in the BSW test procedure. 

For tests where the turn signal is 

activated, an additional warning 

modality (i.e., a dual-modality warning) 

or an escalating visual warning signal 

(e.g., switches from steady-burning to 

flashing) is required within the time 

specified in the BSW test procedure. 

For the BSW Straight Lane Converge 

and Diverge scenario, the test speed for 

both the subject vehicle and principal 

other vehicle will be 72.4 kph (45.0 

mph). For the BSW Straight Lane Passby scenario, NHTSA will conduct the 

lowest speed differential condition 

(subject vehicle/principal other vehicle 

speeds of 72.4/80.5 kph (45.0/50.0 

mph)) first. If the subject vehicle issues 

a passing BSW during the run, the 

principal other vehicle speed will be 

incrementally increased by 8.0 kph (5.0 

mph) and testing will continue with one 

run conducted per speed differential 

condition until a principal other vehicle 

speed of 104.6 kph (65.0 mph) is 

reached. Testing will then be repeated 

following a similar methodology for 

principal other vehicle movement on 

the opposite side of the subject vehicle. 

If, for any speed differential condition, 

the subject vehicle does not issue a 

passing BSW, NHTSA will discontinue 

BSW testing for that vehicle model. 

Only one trial per BSW test condition 

will be conducted. An overview of the 

test scenarios and test parameters for the 

BSW tests is presented in Table 5. To 

obtain credit for BSW, the vehicle must 

pass all 20 tests for BSW. 

TABLE 5—BLIND SPOT WARNING (BSW) ADOPTED TEST CONDITIONS

Test scenario SV speed (kph 

(mph)) 

POV speed 

(kph (mph)) 

POV direction of 

approach Turn signal 

Straight Lane .......................................................................

Converge and Diverge ........................................................

72.4 (45) 72.4 (45) Right .............................. Enabled 

Disabled 

Left ................................ Enabled 

Disabled 

Straight Lane Pass-by ........................................................ 72.4 (45) 80.5 (50) Right .............................. Enabled 

Disabled 

Left ................................ Enabled 

Disabled 

88.5 (55) Right .............................. Enabled 

Disabled 

Left ................................ Enabled 

Disabled 

96.6 (60) Right .............................. Enabled 

Disabled 

Left ................................ Enabled 

Disabled 

104.6 (65) Right .............................. Enabled 

Disabled 

Left ................................ Enabled 

Disabled 


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95922 Federal Register / Vol. 89, No. 232 / Tuesday, December 3, 2024 / Notices 

24These three scenarios for assessing BSI were 

proposed in the March 2022 RFC notice and are 

described in a later section of the notice. 

BSI will be evaluated using tests 

representing two lane change scenarios 

(Subject Vehicle Lane Change with 

Constant Headway and Subject Vehicle 

Lane Change with Closing Headway) 

and one false positive scenario (Subject 

Vehicle Lane Change with Constant 

Headway False Positive Assessment),24

using Revision G of the ABD GVT as the 

principal other vehicle. All BSI 

evaluations will be conducted with 

adaptive cruise control (ACC), lane 

centering assistance (LCA), and/or lane 

keeping assist (LKA) technologies (if 

equipped and if the systems can be 

disengaged) turned off. 

For the BSI Subject Vehicle Lane 

Change with Constant Headway and the 

False Positive tests, the test speed for 

both the subject vehicle and principal 

other vehicle will be 72.4 kph (45.0 

mph). For the BSI Subject Vehicle Lane 

Change with Closing Headway tests, the 

subject vehicle test speed will be 72.4 

kph (45.0 mph) and the principal other 

vehicle speed will be 80.5 kph (50 

mph). In these tests, after a short period 

of steady-state driving, the subject 

vehicle driver (i.e., robot) initiates a lane 

change and follows an 800 m (2,625 ft.) 

radius curved path towards the 

principal other vehicles’ travel lane. The 

subject vehicle driver then releases the 

steering wheel upon the subject vehicle 

exiting the curve so as to achieve a 

steady state lateral velocity of 0.7 ± 0.1 

m/s (2.3 ± 0.3 ft./s) relative to the line 

separating the subject vehicle and 

principal other vehicle travel lanes. 

Each test scenario is conducted with 

turn signal enabled and disabled and for 

both left and right lane change 

directions. 

To pass the Subject Vehicle Lane 

Change with Constant Headway and the 

Subject Vehicle Lane Change with 

Closing Headway tests, the BSI system 

must prevent any contact between the 

subject vehicle and the principal other 

vehicle. The subject vehicle BSI 

intervention must not cause a secondary 

departure on the opposite side of the 

lane. To pass a false positive test, the 

BSI system must not intervene. Only 

one trial per BSI test condition will be 

conducted. An overview of the test 

scenarios and test parameters for the BSI 

tests is presented in Table 6. To obtain 

credit for BSI, the vehicle must pass all 

12 tests. 

TABLE 6—BLIND SPOT INTERVENTION (BSI) ADOPTED TEST CONDITIONS

Test scenario SV speed 

(kph (mph)) 

POV speed 

(kph (mph)) 

Lane 

change 

direction 

Turn signal 

SV Lane Change with Constant Headway ........... 72.4 (45) 72.4 (45) Left Enabled. 

Disabled. 

Right Enabled. 

Disabled. 

SV Lane Change with Closing Headway ............. 72.4 (45) 80.5 (50) Left Enabled. 

Disabled. 

Right Enabled. 

Disabled. 

SV Lane Change with Constant Headway, False 

Positive Assessment.

72.4 (45) 72.4 (45) Left Enabled. 

Disabled. 

Right Enabled. 

Disabled. 

Adding Lane Keeping Assist (LKA) and 

Enhancing Lane Departure Warning 

(LDW) Evaluation 

NHTSA is adding the assessment of 

lane keeping assist (LKA) into NCAP 

and integrating the evaluation of lane 

departure warning (LDW) with the LKA 

evaluation. To evaluate a vehicle’s LDW 

sensitivity and LKA intervention 

capabilities, NHTSA’s testing includes 

the use of a single solid white lane line, 

dashed yellow lane line, or Botts’ dots 

(raised pavement markers) on either the 

right or left side of the vehicle’s travel 

lane, depending on testing direction. 

Additional tests will be conducted with 

two lane lines (solid yellow and dashed 

white lines, and dashed white and solid 

white lines) to evaluate a vehicle’s 

ability to properly correct its heading to 

prevent a secondary lane departure after 

the initial intervention. For the LDW/ 

LKA tests, the subject vehicle, traveling 

at a speed of 72.4 kph (45 mph), heads 

towards the lane line using an initial 

path defined by a 1,200 m (3,937 ft.) 

radius curve. Tests will be conducted by 

incrementing the lateral velocity of the 

subject vehicle’s approach toward the 

lane line from 0.2 to 0.6 m/s (0.7 to 2.0 

ft./s) in 0.1 m/s (0.3 ft./s) increments. 

To pass the criteria of the LDW/LKA 

evaluation test, the subject vehicle must 

issue a visual signal when the lateral 

position of the vehicle, represented by 

a two-dimensional polygon, is within 

0.75 m (2.5 ft.) of the inboard edge of the 

lane line and before the lane departure 

exceeds 0.3 m (1 ft.). The LKA 

intervention itself will serve as a 

secondary haptic alert component. 

Neither an LDW nor LKA intervention 

shall occur when a vehicle has not 

departed its lane and is farther than 0.75 

m (2.5 ft.) from the inboard edge of the 

lane line. In addition, the visual 

warning signal and LKA intervention 

must be issued before the lane departure 

exceeds 0.3 m (1 ft.), and the visual alert 

must be issued prior to, or concurrent 

with, the start of the LKA intervention. 

Only one trial per test condition is 

conducted. An overview of the test 

scenarios and test parameters for the 

LDW/LKA tests is presented in Table 7. 

To obtain credit for LDW and LKA, the 

vehicle must pass all 50 tests performed 

during the LDW/LKA performance 

assessment. 


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Federal Register / Vol. 89, No. 232 / Tuesday, December 3, 2024 / Notices 95923 

TABLE 7—LANE DEPARTURE WARNING (LDW)/LANE KEEPING ASSIST (LKA) ADOPTED TEST CONDITIONS

Test scenario Line type Departure 

direction 

Lateral 

velocity 

(m/s (ft./s)) 

Passing criteria 

Maximum SV 

excursion 

(m (ft.)) 

LDW alert issued 

(m (ft.)) 

Primary Departure ................

(Single Straight Lane Line) ..

Solid White ........ Left 0.2 (0.7) 

0.3 (1.0) 

0.4 (1.3) 

0.5 (1.6) 

0.6 (2.0) 

¥0.3 (¥1.0) 0.75 to ¥0.3 

(2.5 to ¥1.0). 

Solid White ........ Right 0.2 (0.7) 

0.3 (1.0) 

0.4 (1.3) 

0.5 (1.6) 

0.6 (2.0) 

Dashed Yellow .. Left 0.2 (0.7) 

0.3 (1.0) 

0.4 (1.3) 

0.5 (1.6) 

0.6 (2.0) 

Dashed Yellow .. Right 0.2 (0.7) 

0.3 (1.0) 

0.4 (1.3) 

0.5 (1.6) 

0.6 (2.0) 

Raised Pavement Markers.Left 0.2 (0.7) 

0.3 (1.0) 

0.4 (1.3) 

0.5 (1.6) 

0.6 (2.0) 

Raised Pavement Markers.Right 0.2 (0.7) 

0.3 (1.0) 

0.4 (1.3) 

0.5 (1.6) 

0.6 (2.0) 

Secondary Departure ...........

(Dual Straight Lane Line) .....

Solid Yellow (L)/ 

Dashed White 

(R).

Left 0.2 (0.7) 

0.3 (1.0) 

0.4 (1.3) 

0.5 (1.6) 

0.6 (2.0) 

¥0.3 (¥1.0) 0.75 to ¥0.3 

(2.5 to ¥1.0). 

Solid Yellow (L)/ 

Dashed White 

(R).

Right 0.2 (0.7) 

0.3 (1.0) 

0.4 (1.3) 

0.5 (1.6) 

0.6 (2.0) 

Dashed White 

(L)/Solid White 

(R).

Left 0.2 (0.7) 

0.3 (1.0) 

0.4 (1.3) 

0.5 (1.6) 

0.6 (2.0) 

Dashed White 

(L)/Solid White 

(R).

Right 0.2 (0.7) 

0.3 (1.0) 

0.4 (1.3) 

0.5 (1.6) 

0.6 (2.0) 

NCAP Roadmap 2024–2033 

NHTSA has developed a final 

roadmap to update NCAP through 

multiple phases from 2024 through 

2033, with mid-term roadmap items 

spanning the period 2024–2028, and 

long-term items spanning the period 

2024–2033. The NCAP roadmap 

includes four phases for each NCAP 

initiative, along with a completion 

milestone for each phase. The four 

phases are: (1) Research phase, if 

applicable, (2) Request for comment 

(RFC) phase, (3) Final decision phase, 

and (4) Implementation phase. NHTSA 

plans updates to NCAP in the following 

three safety programs: crashworthiness, 

crash avoidance, and vulnerable road 

user safety. A summary of the mid-term 

and long-term actions for this roadmap 

is presented in Tables 8 and 9, 

respectively. The timeframe shown for 

the research, RFC, and final decision 

phases is in calendar years. The start of 

the implementation phase is in the 

fourth quarter of the calendar year 

shown in the two tables. Note that the 

implementation phase starts with 

vehicle models of the following 

calendar year shown in Tables 8 and 9. 

NHTSA plans to update the NCAP 

roadmap approximately every four 

years, with timelines updated 

accordingly. Details of the NCAP 

roadmap are provided in the roadmap 

section of this notice. 


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95924 Federal Register / Vol. 89, No. 232 / Tuesday, December 3, 2024 / Notices 

25 73 FR 40016 (July 11, 2008). 

TABLE 8—ROADMAP FOR MID-TERM UPGRADES TO NCAP 

[In calendar years] 

Potential updates to NCAP 

evaluations 

Research 

phase RFC phase 

Final 

decision 

phase 

Implementation 

phase start 

in 4th quarter 

Crash Avoidance Program: 

Enhanced FCW, CIB, DBS .............................................................................. .................... .................... 2023–2024 2025 

LDW+LKA and BSW+BSI ................................................................................ .................... .................... 2023–2024 2025 

Rear Automatic Braking ................................................................................... 2024 2025 2025–2026 2027 

Crashworthiness Program: 

THOR–50M in Frontal Crash Tests and HIII–05F * in Driver Position in Frontal Rigid Barrier Crash Test .......................................................................... 2024 2024–2025 2025–2026 2027 

Frontal Oblique Crash Test with THOR–50M .................................................. 2024 2024–2025 2025–2026 2027 

WorldSID–50M in Side Impact Tests, and SID–IIs ** Rib Deflections for Injury Risk Assessment ................................................................................... 2024 2024–2025 2025–2026 2027 

Vulnerable Road User (VRU) Safety Program: 

PAEB (day and night-time) ............................................................................... .................... .................... 2023–2024 2025 

Crashworthiness Pedestrian Protection ........................................................... .................... .................... 2023–2024 2025 

Unattended Child Alert System (Availability of Direct Sensing Technologies 

Noted in Safety Features Section on Ratings Webpage) ............................ .................... .................... .................... 2024 

Bicyclist and Motorcyclist AEB (along path scenarios) .................................... 2024–2025 2025 2025–2026 2027 

Vehicle Safety Rating: 

Rating System for Crash Avoidance Technologies ......................................... .................... .................... 2024–2025 2027 

Rating Systems for Crashworthiness, VRU Safety, and Overall Safety .......... .................... 2024–2025 2025–2026 2027 

Monroney Label Rulemaking—Crash Avoidance, Crashworthiness, VRU 

Safety, and Overall Safety Ratings .............................................................. 2023–2024 2025 2025–2026 2027 

* The advanced 5th percentile female frontal impact test dummy, THOR–05F, is currently under evaluation/refinement and is included in the 

long-term NCAP update in this roadmap. Until THOR–05F is completed and included in NCAP, NHTSA will use the current HIII–05F dummy in 

frontal crash tests. 

** The advanced 5th percentile female side impact test dummy, WorldSID–05F, is currently under development and its use in NCAP will be 

considered in the long-term section of this roadmap. Until WorldSID–05F is included in NCAP, the SID–IIs will be used in NCAP along with thoracic and abdominal deflection measurements. 

TABLE 9—ROADMAP FOR LONG-TERM UPGRADES TO NCAP 

[In calendar years] 

Potential updates to NCAP 

Evaluations 

Research 

phase RFC phase 

Final 

decision 

phase 

Implementation 

phase start 

in 4th quarter 

Crash Avoidance Program: 

Headlighting System (Advanced Driving Beam, Semi-Automatic Beam 

Switching, and Lower Beam Headlamp) ...................................................... 2024–2026 2026–2027 2028 2030 

AEB for Intersection Crash Scenarios ............................................................. 2025–2027 2028 2029 2031 

Enhanced LKA (Higher Speed, Curved Road and/or Road Edge Detection 

Scenarios) ..................................................................................................... 2024–2026 2027 2028 2030 

Enhanced AEB (Speed and Additional Scenarios) .......................................... 2026–2028 2029 2030 2032 

Driver Monitoring Systems—Distracted/Drowsy Driving .................................. 2023–2027 2028 2029 2031 

Intelligent Speed Assist .................................................................................... 2024–2028 

Crashworthiness Program: 

THOR–05F in Frontal Crash Tests in Front and Rear Seating Positions ....... 2023–2027 2027–2028 2028–2029 2031 

WorldSID–05F in Side Impact Crash Tests ..................................................... 2023–2029 2029–2030 2030–2031 2033 

VRU Safety Program: 

Enhanced AEB for Bicyclists and Motorcyclists in Intersection Crashes ........ 2025–2026 2027 2028 2030 

BSW and BSI Evaluation for Bicyclists and Motorcyclists Crash Protection ... 2025–2026 2027 2028 2030 

Crashworthiness Pedestrian Protection using aPLI * ....................................... 2024–2025 2026 2027 2029 

Enhanced PAEB (Speed and Additional Scenarios) ....................................... 2026–2028 2029 2030 2032 

Driver Visibility .................................................................................................. 2023–2027 

* aPLI is the advanced pedestrian legform impactor. It assesses pedestrian injuries to the knee, upper leg, and lower leg in impacts with the 

front of vehicles. 

III. Background 

The National Highway Traffic Safety 

Administration’s (NHTSA’s) New Car 

Assessment Program (NCAP) supports 

the Agency’s mission to reduce the 

number of fatalities and injuries that 

occur on U.S. roadways by providing 

important vehicle safety information to 

consumers to inform their purchasing 

decisions. The last major NCAP upgrade 

occurred on July 11, 2008, and took 

effect with model year 2011 vehicles.25

That program update included the 

Agency’s adoption of new frontal and 

side anthropomorphic test devices 

(crash test dummies) and associated 

injury criteria, a new oblique side pole 

test, and a new overall rating system 

combining the individual frontal, side, 

and rollover ratings. NHTSA also 

expanded NCAP to include assessment 

of three advanced driver assistance 

systems (ADAS) technologies: forward 

collision warning (FCW), lane departure 

warning (LDW), and electronic stability 


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Federal Register / Vol. 89, No. 232 / Tuesday, December 3, 2024 / Notices 95925 

26ESC was removed from the Agency’s list of 

recommended ADAS technologies through NCAP 

beginning in model year 2014 when the technology 

became mandated under Federal motor vehicle 

safety standard (FMVSS) No. 126, ‘‘Electronic 

stability control.’’ NHTSA also included rear video 

systems in its list of recommended technologies 

under NCAP from model years 2014 to 2017 and 

removed that technology from its list when it 

became mandated under FMVSS No. 111, ‘‘Rear 

visibility.’’ 

27 80 FR 68604 (Nov. 5, 2015). 

28 80 FR 78521 (Dec. 16, 2015). 

29See NCAP Rating FAQ No. 07, http://nhtsa.gov/ 

ratings. 

control (ESC).26 Through that 

expansion, the Agency began to identify 

which vehicles were equipped with 

these technologies and met specified 

performance requirements, making this 

information available on the NHTSA 

website. In November 2015, NHTSA 

also added crash imminent braking 

(CIB) and dynamic brake support (DBS) 

technologies (also known as automatic 

emergency braking, or AEB technology) 

to its ADAS assessments, with 

implementation beginning with model 

year 2018 vehicles.27

In December 2015, the Agency 

published a Request for Comments 

(RFC) notice with planned changes to 

the overall NCAP program. The notice 

sought comment on NCAP’s potential 

use of enhanced tools and techniques to 

evaluate the safety of vehicles, generate 

star ratings, and encourage further 

vehicle safety developments.28 The RFC 

notice also outlined planned changes for 

the crashworthiness, crash avoidance, 

and ratings categories. Many 

commenters responding to the 

December 2015 RFC notice stated it 

lacked sufficient detail and supporting 

information to allow for thorough 

review and comment. Commenters also 

expressed concern over test procedure 

repeatability and reproducibility based 

on the RFC notice’s lack of detail, 

performance criteria, and nonstandardized test devices. NHTSA 

hosted a public meeting in October 2018 

to re-engage stakeholders and seek upto-date input to help the Agency plan 

the future of NCAP. 

On March 9, 2022, NHTSA published 

an RFC notice proposing changes to 

NCAP in response to the comments 

received from the 2015 RFC and public 

meetings, which partially fulfills the 

Agency’s obligations under the 2015 

Fixing America’s Surface Transportation 

(FAST) Act directive and recent 

mandates included in section 24213 of 

the November 2021 Bipartisan 

Infrastructure Law (BIL). The proposed 

changes include: 

• Changes to test procedures and 

performance criteria, including an 

increase in stringency, for the four 

currently recommended ADAS 

technologies in NCAP (FCW, LDW, 

DBS, and CIB) to enhance evaluation of 

the systems’ capabilities in current 

vehicle models, reduce test burden, and 

promote harmonization with other 

consumer information programs. 

• The addition of four new ADAS 

technologies—blind spot warning 

(BSW), blind spot intervention (BSI), 

lane keeping assist (LKA), and 

pedestrian automatic emergency braking 

(PAEB)—to those currently 

recommended by NCAP and highlighted 

on the Agency’s website. The Agency 

proposed to incorporate these four new 

ADAS technologies into NCAP because 

data indicates they satisfy NHTSA’s four 

prerequisites for inclusion in the 

program: (1) a known safety need exists; 

(2) system designs (countermeasures) 

exist that can mitigate the safety 

problem; (3) existing or new system 

designs have the potential to improve 

safety; and (4) a performance-based 

objective test procedure exists that can 

assess system performance.29

• A ‘‘roadmap’’ of the Agency’s plans 

to update NCAP in phases over the next 

ten years, setting forth NHTSA’s midterm and long-term strategies for 

upgrading the program using a phased 

approach. The roadmap presents an 

estimated timeframe for the issuance of 

phased request for comment notices to 

incorporate various potential program 

components. However, NHTSA would 

only issue proposals to update the 

program as technologies mature and are 

considered ready for inclusion such that 

they meet the program’s four 

prerequisites. Following each proposal, 

NHTSA will issue a final decision 

notice responding to the comments 

received and providing the Agency’s 

decisions for that particular program 

update, as well as the lead time for 

implementation. 

In addition to these proposed 

changes, the RFC notice proposed 

operational changes to streamline the 

information provided to consumers. 

Specifically, the Agency proposed a 

process for updating ADAS-related 

information provided to consumers to 

reflect changes made to vehicles during 

the middle of a model year. Further, 

although not explicitly proposed in the 

RFC notice, the Agency sought comment 

on the following topics to help guide 

future proposals: 

• The Agency’s plan to develop a new 

ADAS rating system for NCAP to 

provide consumers with improved data 

to compare and shop for vehicles and 

spur improved ADAS performance. 

NCAP currently assigns ratings to 

vehicles based on their performance in 

crashworthiness (i.e., frontal and side 

impact) and rollover tests, but the 

program has no complementary rating 

system to differentiate performance 

among vehicles’ crash avoidance 

systems. Instead, NCAP only 

recommends certain ADAS technologies 

to shoppers and identifies vehicles that 

offer the recommended technologies 

that pass the program’s system 

performance criteria. 

• Steps to include crash avoidance 

rating information on a vehicle’s 

window sticker (i.e., the Monroney 

label) at the point of sale, consistent 

with the 2015 FAST Act. The Agency 

noted that it is currently conducting 

consumer research to determine how 

best to present such information to 

maximize its effectiveness in informing 

vehicle purchasing decisions. NHTSA 

stated that it would consider the 

information gained from this research in 

conjunction with related comments 

received in response to the 2022 RFC to 

develop a proposal for a revised label, 

which will be detailed in a separate RFC 

notice. 

• Expanding NCAP to include safety 

technologies that promote NHTSA’s 

continuing efforts to combat unsafe 

driving or riding behaviors, such as 

speeding and drowsy, impaired, 

distracted, and unbelted driving, as well 

as safety technologies that may prevent 

unintentional human behavior that may 

result in injury or death, such as 

vehicular heatstroke. 

• The Agency’s ideas for updating 

several programmatic aspects of NCAP, 

including adding new crash test 

dummies, updating the rollover risk 

curve, and enhancing the presentation 

and dissemination of safety information 

provided to consumers to improve the 

program. More specifically, NHTSA 

requested comment on several potential 

ways to revise the 5-star safety ratings 

system, including adopting a pointsbased rating system concept, revising 

the baseline risk, and incorporating 

decimal or half-star ratings. 

• Additional considerations that 

would allow NCAP to remain effective 

and relevant to improve vehicle safety, 

such as proposed updates to the NCAP 

website and the development of an 

NCAP database to modernize the 

operational aspects of the program, 

including a new vehicle information 

submission process for vehicle 

manufacturers. 

Following publication of the March 

2022 RFC notice, NHTSA received 

comments generally supportive of the 

Agency’s proposal to adopt additional 

crash avoidance elements. Additional 

details of NHTSA’s proposal for each of 


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95926 Federal Register / Vol. 89, No. 232 / Tuesday, December 3, 2024 / Notices 

30The March 2022 RFC notice requested 

comment on a number of topics, including 

emerging technologies, and potential future updates 

to NCAP, that have not been proposed, and thus are 

not addressed, in the present notice. Details of the 

comments received and the Agency’s response to 

these comments will be provided in future RFC 

notices relevant to those topics. 

the items listed above is provided in 

later sections. 

Summary of General Comments on 

Proposed Updates to NCAP 

NHTSA received over 4,000 

comments in response to the March 

2022 RFC notice.30 The Agency received 

comments from a wide variety of 

commenters including safety advocacy 

groups, trade associations, vehicle 

manufacturers, suppliers and 

developers, government agencies and 

associations, test laboratories, an 

insurance company, a research/ 

consulting firm, and individual 

members of the public. A summary of 

the commenters to the March 2022 RFC 

notice is provided in Table 10. 

TABLE 10—COMMENTERS TO THE MARCH 2022 NCAP RFC NOTICE

Category Commenters 

Safety Advocacy Groups ................................................ AAA Inc. (AAA), AARP, Advanced Mobility Group, Advocates for Highway and Auto Safety (Advocates), 

American Motorcyclist Association (AMA), Center for Auto Safety (CAS), Consortium for Constituents with 

Disabilities Transportation Task Force (CCD Transportation Task Force), Consumer Reports (CR), Insurance Institute for Highway Safety (IIHS), Kids and Car Safety (KAC), Families for Safe Streets (FSS), Intelligent Transportation Society of America (ITS America), Massachusetts Vision Zero Coalition, The 

League of American Bicyclists (The League), Vision Zero Network (VZN), and ZF Group. 

Industry Trade Associations ........................................... Alliance for Automotive Innovation (Auto Innovators), Automotive Safety Council (ASC), Motor & Equipment 

Manufacturers Association (MEMA), Motorcycle Industry Council and Motorcycle Safety Foundation (MIC/ 

MSF), National Automobile Dealers Association (NADA), Specialty Equipment Market Association 

(SEMA), The Lidar Coalition. 

Vehicle Manufacturers .................................................... American Honda Motor Co., Inc. (Honda), BMW of North America, LLC (BMW), FCA US LLC (FCA), Ford 

Motor Company (Ford), General Motors (GM), Hyundai America Technical Center, Inc. (HATCI), Hyundai 

Motor North America (Hyundai), Mercedes-Benz, LLC, a division of Mercedes-Benz Automotive Group 

(Mercedes-Benz), North American Subaru, Inc. (Subaru), Rivian Automotive, LLC (Rivian), Tesla, Inc. 

(Tesla), Toyota Motor North America (Toyota). 

Suppliers and Developers .............................................. Aptiv PLC (Aptiv), Bosch LLC (Bosch), DENSO Corporation (DENSO), Intel Corporation (Intel), Robert 

Vayyar, Velodyne Lidar, Inc. (Velodyne). 

Government Agencies and Associations ....................... American Association of State Highway and Transportation Officials (AASHTO), National Association of City 

Transportation Officials (NACTO), National Transportation Safety Board (NTSB), New York City Department of Transportation & New York City Department of Citywide Administrative Services, Vision Zero 

Task Force (NYC DOT/NYC DCAS, Vision Zero Task Force). 

Test Laboratories ........................................................... Applus IDIADA (IDIADA), Dynamic Research Inc. (DRI), Transportation Research Center, Inc. (TRC). 

Insurance Companies .................................................... State Farm Insurance Companies (State Farm). 

Research/Consulting Companies ................................... Safe Streets Research & Consulting (Safe Streets). 

General Public ................................................................ Individuals. 

Many commenters stated they support 

NHTSA’s goal of providing comparative 

safety information to consumers through 

NCAP but encouraged the Agency to 

further leverage NCAP to ensure 

consumers have a comprehensive 

understanding of vehicle safety. 

Commenters also stated that more 

testing, rating, and information-sharing 

with consumers about the 

functionalities of advanced safety 

technologies via NCAP will promote the 

technologies’ use in future vehicles and 

advance vehicle safety. The Alliance for 

Automotive Innovation (Auto 

Innovators) stated it supports NHTSA’s 

efforts to modernize NCAP, noting that 

a key benefit of a well-developed and 

technically robust NCAP is the 

introduction of advanced safety 

technologies and performance 

evaluation through market incentives 

(objective ratings) in a structured and 

predictable manner via the development 

of testing procedures, evaluation 

metrics, and safety benefits. Auto 

Innovators stated that doing so will lead 

to more vehicles being equipped with 

new ADAS technologies, ultimately 

decreasing technology costs, and 

bolstering the case for potential 

regulation. 

Many commenters, including those 

who have lost loved ones in automotive 

accidents, expressed support for the 

proposed NCAP changes but stated they 

do not go far enough, noting the U.S. 

program is behind other countries’ 

NCAP programs in updating, 

implementing, and ‘‘standardizing’’ 

NCAP with proven safety technologies 

to save more lives. The Advocates for 

Highway and Auto Safety (Advocates), 

the Consumer Federation of America, 

and many others expressed concern that 

the approach described in the March 

2022 RFC is not sufficiently specific and 

lacks firm commitments on key updates 

to the program. Further, the National 

Safety Council (NSC) stated that its data 

continues to suggest NHTSA is not 

doing enough to address roadway safety, 

with thousands of people dying in 

preventable crashes each year. 

Several commenters pointed out that 

fatalities involving pedestrians and 

cyclists have been increasing at 

alarming rates and urged NHTSA to 

consider the safety of those outside of 

the vehicle. Many cyclist organizations 

stated that any NCAP updates should 

include cyclist AEB testing and tests 

aimed at increasing cyclist safety. One 

individual noted the more than 50 

percent increase in annual pedestrian 

fatalities in the past decade, stating that 

safety innovations are benefiting those 

inside, not outside, of the vehicle. Many 

other individual commenters expressed 

concern for the safety of pedestrians, 

mobility device users, and cyclists 

amidst rising fatalities from increasingly 

large vehicles, suggesting that NHTSA 

should consider promoting technologies 

and performing tests to protect them. 

Many commenters expressed support 

for the Agency’s proposed inclusion of 

the four new ADAS technologies and for 

enhancing the evaluation of ADAS 

technologies currently in NCAP. 

However, some commenters argued the 

proposal did not go far enough, 

suggesting that ADAS technologies 

(including PAEB) should not just be part 

of the voluntary NCAP program but 

should be mandatory on new vehicles to 

reduce fatalities, especially in urban 

areas. Many commenters also requested 

that NHTSA harmonize test procedures 

and evaluations with other existing 

testing protocols like Euro NCAP. While 

commenters generally supported the 

proposed roadmap, some noted that it 


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Federal Register / Vol. 89, No. 232 / Tuesday, December 3, 2024 / Notices 95927 

31Wang, J.-S. (2019, March), Target crash 

population for crash avoidance technologies in 

passenger vehicles (Report No. DOT HS 812 653). 

Washington, DC: National Highway Traffic Safety 

Administration. 

32The Abbreviated Injury Scale (AIS) is a 

classification system for assessing impact injury 

severity. AIS ranks individual injuries by body 

region on a scale of 1 to 6 where 1=minor, 

2=moderate, 3=serious, 4=severe, 5=critical, and 

6=maximum (untreatable). MAIS represents the 

maximum injury severity, or AIS level, recorded for 

an occupant (i.e., the highest single AIS for a person 

with one or more injuries). 

33Leslie, A.J., Kiefer, R.J., Meitzner, M.R., & 

Flannagan, C.A. (2019), Analysis of the field 

effectiveness of General Motors production active 

safety and advanced headlighting systems, The 

University of Michigan Transportation Research 

Institute and General Motors LLC. UMTRI–2019–6. 34Cicchino, J.B. (2017, February), Effectiveness of 

forward collision warning and autonomous 

emergency braking systems in reducing front-to-rear 

crash rates, Accident Analysis and Prevention, 2017 

Feb;99(Pt A):142–152. https://doi.org/10.1016/j.aap.

2016.11.009. 

35Low-speed AEB showed a 43% reduction. 

36Closing velocity is the rate at which two objects 

are getting closer to each other. 

37 73 FR 40033 (July 11, 2008). 38Cicchino, J.B. (2017, February), Effectiveness of 

forward collision warning and autonomous 

emergency braking systems in reducing front-to-rear 

crash rates, Accident Analysis and Prevention, 2017 

Feb;99(Pt A):142–152. https://doi.org/10.1016/ 

j.aap.2016.11.009. 

39Consumer Reports (2019, November), 

Consumer Perception of ADAS, https://

data.consumerreports.org/reports/consumerperceptions-of-adas/. 

40 73 FR 40016 (July 11, 2008). 

41National Highway Traffic Safety 

Administration. (2013, February). Forward collision 

warning system confirmation test. https://

www.regulations.gov. Docket No. NHTSA–2006– 

26555–0134. 

lacked sufficient specificity on future 

timelines, dates, and required actions. 

Commenters requested periodic 

stakeholder engagement and 

collaboration for developing future 

NCAP roadmaps. 

Several commenters also provided 

detailed responses to questions NHTSA 

posed in the March 2022 RFC notice to 

help guide its decisions. The following 

sections discuss in detail: (1) NHTSA’s 

proposal for each technology, (2) the 

Agency’s response to the comments 

received to the questions posed, and (3) 

final decisions on the proposed changes 

to NCAP specific to the technology. 

IV. Updating Forward Collision 

Prevention Technologies 

NHTSA is updating assessments for 

FCW and AEB technologies (i.e., CIB 

and DBS) in NCAP’s crash avoidance 

program. As discussed in NHTSA’s 

March 2022 RFC notice, these 

technologies, designed to address 

forward collisions (rear-end crashes), 

have the potential to help prevent or 

mitigate rear-end pre-crash scenarios 

representing approximately 1.7 million 

crashes annually, or 29 percent of all 

crashes that currently occur on U.S. 

roadways.31 These crashes result in 

1,275 fatalities, on average, and 883,386 

MAIS 1–5 injuries annually, 

representing 3.8 percent of all fatalities 

and 32 percent of all injuries, 

respectively.32 FCW and AEB 

technologies have proven effective in 

reducing crashes, fatalities, and injuries. 

For instance, as discussed in the March 

2022 RFC notice, the University of 

Michigan Transportation Research 

Institute (UMTRI) found that for 3.8 

million model year 2013–2017 GM 

vehicles, camera-based FCW systems 

produced an estimated 21 percent 

reduction in rear-end striking crashes, 

while the AEB systems studied (which 

included a combination of camera-only, 

radar-only, and fused camera-radar 

systems) produced an estimated 46 

percent reduction in the same crash 

type.33 These findings align with a 2017 

Insurance Institute for Highway Safety 

(IIHS) study,34 which concluded that 

vehicles equipped with FCW and AEB 

showed a 50 percent reduction for the 

same crash type.35

Until these technologies are standard 

equipment on all passenger vehicles, it 

is important for NCAP to continue to 

recommend FCW and AEB technologies 

to consumers and to inform them which 

vehicles have FCW and AEB 

technologies meeting NHTSA’s 

performance criteria. Further, given 

recent increases in the penetration of 

FCW and AEB technologies in the 

vehicle fleet and improvements to 

sensors, now is an opportune time to 

increase the stringency of the current 

NCAP performance requirements for 

these technologies. 

A. Forward Collision Warning (FCW) 

FCW systems use forward-looking 

sensors (e.g., radar, lidar, camera 

systems, or a combination thereof) that 

detect objects (e.g., vehicles, 

pedestrians) in front of vehicles and 

issue an alert to the driver. An FCW 

system uses the sensors’ input to 

determine the speed of the object in 

front of it and the distance between the 

vehicle and the object. If the sensing 

system determines that the closing 

distance and velocity 36 between the 

driver’s vehicle and the object in front 

of it is such that a collision may be 

imminent, the warning system is 

designed to induce an immediate crash 

avoidance response by the vehicle 

operator. Warning systems in use today 

provide drivers with a visual display, 

such as an illuminated telltale on or 

near the instrument panel, an auditory 

signal (e.g., buzzer or chime), and/or a 

haptic signal that provides tactile 

feedback (e.g., rapid vibrations of the 

seat pan or steering wheel). These 

signals warn the driver of an impending 

collision so the driver may then 

manually intervene (e.g., apply the 

vehicle’s brakes or make an evasive 

steering maneuver) to avoid or mitigate 

a crash. FCW systems alone do not 

brake the vehicle. 

NHTSA added FCW systems to its 

NCAP ADAS evaluations in 2008 (with 

performance evaluations beginning with 

model year 2011 vehicles) because these 

systems met the Agency’s four 

prerequisites for inclusion at the time.37

In its March 2022 RFC notice, the 

Agency proposed to continue to include 

FCW assessments in NCAP, as it found 

FCW systems to be effective, wellaccepted by consumers, and widely 

available in the current vehicle fleet. For 

example, in its 2017 study, IIHS 38

found that FCW systems reduced rearend crashes by 27 percent. Further, in 

a 2019 survey of more than 57,000 

Consumer Reports subscribers, 69 

percent of vehicle owners reported they 

were satisfied with their vehicle’s FCW 

technology.39 Currently, manufacturersubmitted data collected by NHTSA 

indicates 91 percent of model year 2023 

vehicles are equipped with FCW 

systems as standard equipment. 

NCAP’s Current Forward Collision 

Warning Test Procedure 

The Agency included FCW as a 

recommended technology in NCAP and 

conducted performance evaluations 

beginning with model year 2011 

vehicles. The FCW test procedure 

adopted at that time is still in use in the 

Agency’s testing today.40

Currently, NCAP’s FCW test 

procedure 41 consists of three scenarios 

that simulate the most frequent types of 

rear-end crashes. These include lead 

vehicle stopped (LVS), lead vehicle 

decelerating (LVD), and lead vehicle 

moving (LVM) scenarios. In each 

scenario, the vehicle being evaluated is 

called the subject vehicle (SV). The SV 

is driven by a professional driver who 

provides the necessary acceleration, 

braking, and steering inputs during the 

test. A production mid-size passenger 

car, designated as the principal other 

vehicle (POV) during testing, is 

positioned directly in front of the SV 

and is also driven by a professional 

driver. Time-to-collision (TTC) criteria 

are prescribed for each FCW scenario. 

The TTC for each scenario is calculated 

by considering the speed of the SV 

relative to the POV at the time of the 

FCW. If the FCW system fails to issue 

a warning within the required time 

during testing, the SV’s professional test 


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42As noted in the Agency’s 2015 AEB final 

decision notice (80 FR 68618 (Nov. 5, 2015)), a pass 

rate of five out of seven tests per scenario was 

adopted for NCAP’s current FCW test protocol to 

provide the Agency with a way to encourage system 

robustness without precluding the proliferation of 

emerging technologies offering the potential for 

significant safety benefits. 

43Some FCW systems use haptic brake pulses to 

alert the driver of a crash-imminent driving 

situation, but they are not intended to effectively 

slow the vehicle. 

44Leslie, A.J., Kiefer, R.J., Meitzner, M.R., & 

Flannagan, C.A. (2019, September), Analysis of the 

field effectiveness of General Motors production 

driver brakes, or steers away, to avoid a 

collision with the POV. A short 

description of each test scenario and the 

requirements for a passing result based 

on the prescribed TTC is provided 

below: 

• LVS—The SV encounters a stopped 

POV directly in front of it on a straight 

road. The SV is moving at 72.4 kph (45 

mph), and the POV is stationary. To 

pass this test, the SV must issue an FCW 

when the TTC is at least 2.1 s. See 

Figure 1 (below) for a scenario diagram. 

• LVD—The SV encounters a POV 

slowing with constant deceleration 

directly in front of it on a straight road. 

The SV and POV are both driven at 72.4 

kph (45 mph) with an initial headway 

of 30.0 m (98.4 ft.). The POV then 

decelerates, braking at a constant 

deceleration of 0.3g in front of the SV. 

To pass this test, the SV must issue an 

FCW when the TTC is at least 2.4 s. See 

Figure 2 (below) for a scenario diagram. 

• LVM—The SV encounters a slowermoving POV directly in front of it on a 

straight road. The SV and POV are 

driven at constant speeds of 72.4 kph 

(45 mph) and 32.2 kph (20 mph), 

respectively. To pass this test, the SV 

must issue an FCW when the TTC is at 

least 2.0 s. See Figure 3 (below) for a 

scenario diagram. 

Each of these three scenarios is 

conducted up to seven times. To pass 

the NCAP FCW system performance 

tests, the SV must satisfy the respective 

TTC-based performance criteria for at 

least five out of seven trials 42 for each 

of the three test scenarios. 

B. Automatic Emergency Braking (AEB) 

One limitation of FCW systems is 

that, although designed to warn the 

driver of an impending rear-end crash, 

they do not actively and automatically 

assist drivers with avoiding rear-end 

crashes or mitigating their severity. To 

address this, CIB and DBS (known 

collectively as AEB) both provide 

significant automatic braking of the 

vehicle.43 DBS systems provide 

supplemental braking when sensors 

determine that driver-applied braking is 

insufficient to avoid an imminent crash. 

CIB systems provide automatic braking 

when forward-looking sensors indicate 

that a crash is imminent, and the driver 

has not braked. 

Research has shown that active safety 

systems such as AEB provide greater 

safety benefits than the corresponding 

warning systems alone, such as FCW. In 

its 2019 study, UMTRI 44 found that 


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Federal Register / Vol. 89, No. 232 / Tuesday, December 3, 2024 / Notices 95929 

active safety and advanced headlighting systems, 

The University of Michigan Transportation 

Research Institute and General Motors LLC, 

UMTRI–2019–6. 45The AEB systems studied by UMTRI consisted 

of camera-only, radar-only, and fused camera-radar 

AEB systems, the latter two systems of which also 

included adaptive cruise control functionality. 46Consumer Reports, (2019, November), 

Consumer Perceptions of ADAS, https://

data.consumerreports.org/reports/consumerperceptions-of-adas/. 

47 Docket No. NHTSA–2021–0002. 87 FR 13452. 

March 9, 2022. 

48 DBS systems differ from traditional brake assist 

systems used with the vehicle’s foundation brakes. 

Whereas both systems rely on brake pedal 

application rate to determine whether supplemental 

braking is required, DBS has a lower activation 

threshold since it also uses information from 

forward-looking sensors to verify that more braking 

is needed. 

49National Highway Traffic Safety 

Administration (2015, October), Dynamic brake 

support performance evaluation confirmation test 

for the New Car Assessment Program, http://

www.regulations.gov, Docket No. NHTSA–2015– 

0006–0026. 

50The shell is constructed from lightweight 

composite materials with favorable strength-toweight characteristics, including carbon fiber, 

Kevlar®, phenolic, and Nomex honeycomb. It is 

also wrapped with a commercially available vinyl 

material to simulate paint on the body panels, rear 

bumper, and a tinted glass rear window. A foam 

bumper having a neoprene cover is attached to the 

rear of the SSV to reduce the peak forces realized 

immediately after an impact from a test vehicle 

occurs. 

51Minimal activation is defined as a peak SV 

deceleration attributable to DBS intervention that is 

less than or equal to 1.5 times the average of the 

deceleration recorded for the vehicle’s foundation 

brake system alone during its approach to the STP. 

The 1.5 multiplier serves to provide some system 

flexibility, meaning a mild DBS intervention is 

acceptable, but one where the vehicle thinks it must 

respond to the STP as if it was a real vehicle is not. 

52Note that the March 2022 notice specified a 

multiplier of 1.25. This specification was in error. 

AEB systems produced an estimated 46 

percent reduction in applicable rear-end 

crashes when combined with a forward 

collision warning, which alone showed 

only a 21 percent reduction.45 Like FCW 

systems, AEB systems are also wellaccepted by consumers and widely 

available in the current vehicle fleet. In 

Consumer Reports’ 2019 subscriber 

survey, 81 percent of owners of vehicles 

equipped with AEB reported they were 

satisfied with AEB technology.46

Currently, manufacturer-submitted data 

collected by NHTSA indicates 

approximately 91 percent of model year 

2023 vehicles are equipped with AEB 

systems as standard equipment. For 

these reasons, in 2015, NHTSA added 

CIB and DBS technologies to its ADAS 

assessments starting with model year 

2018 vehicles, and why the Agency also 

proposed to continue to include AEB 

assessments in NCAP in its March 2022 

RFC notice.47

1. Dynamic Brake Support (DBS) 

Like FCW (and CIB) systems, DBS 

systems employ forward-looking sensors 

to detect vehicles in the path directly 

ahead while simultaneously monitoring 

the operational state of the driver’s 

vehicle (e.g., speed, the relative speed of 

and distance to the lead vehicle, driver 

inputs of steering and braking). In 

response to an FCW or an imminent 

crash, a driver may initiate braking to 

avoid a rear-end crash. However, 

research suggests that a driver’s brake 

application may not take full advantage 

of the vehicle’s foundation braking 

system in cases where the driver is 

inattentive, receives an FCW, and reengages in the driving task prior to 

automatic braking (i.e., CIB) taking 

place. In situations where the driver’s 

braking is insufficient to prevent a 

collision, DBS can automatically 

supplement the driver’s braking action 

to prevent or mitigate the crash.48 The 

NCAP DBS performance evaluations 

serve to ensure that the vehicle’s 

supplemental braking is sufficient to 

augment the driver’s manual brake 

application and avoid a collision with 

the lead vehicle in the tested driving 

situations. DBS testing also endeavors to 

ensure that a vehicle’s automatic brake 

application (i.e., CIB) is not suppressed 

in the event of a driver’s manual brake 

application. 

NCAP’s Current Dynamic Brake Support 

Test Procedure 

NCAP’s current DBS test procedure 49

consists of the same three rear-end precrash scenarios specified in the FCW 

system performance test procedure: 

LVS, LVD, and LVM. However, most of 

the test speed combinations specified in 

the DBS test procedure differ. The single 

exception is that the FCW and DBS test 

procedures both use an LVM test 

performed with SV and POV speeds of 

72.4 and 32.2 kph (45 and 20 mph), 

respectively. The DBS performance 

assessment also includes a Steel Trench 

Plate (STP) false positive suppression 

test conducted at two test speeds. The 

false positive suppression test series 

evaluates the ability of a DBS system to 

differentiate a steel trench plate, often 

found on roadways, from an object 

presenting a genuine safety risk to the 

SV. Although STPs are large and 

metallic, they are designed to be driven 

over without risk of injury to drivers or 

vehicles. This fourth test scenario is 

used to evaluate the propensity of a 

vehicle’s DBS system to activate 

inappropriately in this non-critical 

driving scenario that would not present 

a safety risk to the vehicle’s occupants. 

Like NCAP’s FCW tests, the vehicle 

subjected to the DBS test scenarios is 

termed the SV. However, unlike NCAP’s 

FCW tests, the DBS test procedure uses 

a surrogate vehicle (i.e., a realistic 

looking artificial vehicle) as the POV 

instead of an actual vehicle to limit the 

potential for damage to the SV and/or 

the test equipment in the event of a 

collision. Additionally, instead of 

driver- (human-) based inputs, like 

those required in NCAP’s FCW tests, a 

programmable (robotic) brake controller 

is used to provide all SV brake pedal 

applications made during the DBS 

system performance evaluations. 

The Strikeable Surrogate Vehicle 

(SSV) is the surrogate vehicle presently 

used as the POV by NCAP for the 

Agency’s DBS testing. The SSV, 

developed by NHTSA for the purpose of 

track testing, appears as a ‘‘real’’ vehicle 

to the camera, radar, and lidar sensors 

used by existing AEB systems. The SSV 

system is comprised of (a) a shell,50

which is a visually and dimensionally 

accurate representation of a compact 

passenger car; (b) a slider and load 

frame assembly to which the shell is 

attached, (c) a two-rail track on which 

the slider operates, (d) a road-based 

lateral restraint track, and (e) a tow 

vehicle, which pulls the SSV and its 

peripherals down the test track during 

the test where the POV (i.e., SSV) must 

be in motion. 

For the three test scenarios where 

braking is expected, the SV must 

provide enough supplemental braking to 

completely avoid contact with the SSV 

(i.e., POV) to pass a trial run. In the case 

of the DBS false positive test scenario, 

the performance criterion is minimal to 

no activation for both test speeds.51 52 A 

short description of each DBS system 

performance test scenario, and the 

requirements for a passing result, is 

provided below: 

• Lead Vehicle Stopped (LVS)—The 

SV encounters a stopped POV directly 

in front of it on a straight road. The SV 

is moving at 40.2 kph (25 mph) and the 

POV is stationary. The SV throttle is 

released within 500 ms after the SV 

issues an FCW, and the SV brake pedal 

is manually applied at a TTC of 1.1 s 

(i.e., at a nominal headway of 12.2 m (40 

ft.)). To pass this test, the SV must not 

contact the POV. See Figure 1 for a 

scenario diagram. 

• Lead Vehicle Decelerating (LVD)— 

The SV encounters a POV slowing with 

constant deceleration directly in front of 

it on a straight road. The SV and POV 

are both driven at 56.3 kph (35 mph) 

with an initial headway of 13.8 m (45.3 

ft.). The POV brakes are then applied to 

achieve a constant deceleration of 0.3g 

in front of the SV. The SV throttle is 

released within 500 ms after the SV 

issues an FCW, and the SV brake pedal 


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53National Highway Traffic Safety 

Administration. (2015, October). Crash imminent 

brake system performance evaluation for the New 

Car Assessment Program. http://

www.regulations.gov. Docket No. NHTSA–2015– 

0006–0025. 

is manually applied at a TTC of 1.4 s 

(i.e., at a nominal headway of 9.6 m 

(31.5 ft.)). To pass this test, the SV must 

not contact the POV. See Figure 2 for a 

scenario diagram. 

• Lead Vehicle Moving (LVM)—The 

SV encounters a slower-moving POV 

directly in front of it on a straight road. 

In the first test, the SV and POV are 

driven on a straight road at a constant 

speed of 40.2 kph (25 mph) and 16.1 

kph (10 mph), respectively. In the 

second test, the SV and POV are driven 

at a constant speed of 72.4 kph (45 mph) 

and 32.2 kph (20 mph), respectively. In 

both tests, the SV throttle is released 

within 500 ms after the SV issues an 

FCW, and the SV brake pedal is 

manually applied at a TTC of 1 s (i.e., 

at a nominal headway of 6.7 m (22 ft.) 

in the first test, and 11.3 m (37 ft.) in 

the second test). To pass these tests, the 

SV must not contact the POV. See 

Figure 3 for a scenario diagram. 

• Steel Trench Plate (STP) false 

positive suppression test—The SV is 

driven over a 2.4 m × 3.7 m × 25.4 mm 

(8 ft. × 12 ft. × 1 in.) steel trench plate 

at 40.2 kph (25 mph) and 72.4 kph (45 

mph). If an FCW is issued, the SV 

throttle is released within 500 ms of the 

alert. If no FCW is issued by a TTC of 

2.1 s, the SV throttle is released within 

500 ms of a TTC of 2.1 s. In both 

instances, the SV brakes are applied at 

a TTC of 1.1 s (i.e., at a nominal distance 

of 12.3 m (40 ft.) from the edge of the 

STP at 40.2 kph (25 mph), or 22.3 m (73 

ft.) at 72.4 kph (45 mph)). To pass this 

test, the performance criterion is 

minimal to no activation, as defined 

previously. See Figure 4 (below) for a 

scenario diagram. 

Currently, to pass NCAP’s DBS system 

performance criteria, the SV must pass 

at least five out of seven trials for each 

of the six test conditions. 

2. Crash Imminent Braking (CIB) 

If a driver does not manually apply 

the vehicle’s brakes when a rear-end 

crash is imminent, CIB systems, using 

the same forward-looking sensors as 

DBS systems, apply the vehicle’s brakes 

automatically to slow or stop the 

vehicle. Unlike DBS systems, which 

provide additional braking to 

supplement the driver’s brake input, 

CIB systems activate when the driver 

has not applied the brake pedal. 

NCAP’s Current Crash Imminent 

Braking (CIB) Test Procedure 

The Agency’s current CIB test 

procedure 53 is comprised of the same 

four test scenarios (LVS, LVD, LVM, and 

the STP false positive suppression test) 

and test speeds specified in the DBS test 

procedure. However, the performance 

criteria vary slightly. Whereas collision 

avoidance is the performance 

requirement stipulated for all DBS test 

scenarios except the false positive 

scenario, only the LVM 40.2 kph/16.1 

kph (25 mph/10 mph) CIB test condition 

requires that the SV not contact the 

POV. The LVS, LVD, and the LVM 72.4 

kph/32.2 kph (45 mph/20 mph) test 

conditions permit SV-to-POV contact 

but require minimum SV speed 

reductions prior to the contact being 

made. For the CIB false positive tests, 

the performance criterion is little-to-no 

activation, like the comparable DBS 

tests. Also, like NCAP’s DBS tests, the 

SSV is the POV presently used in the 

program’s CIB testing. A short 

description of each test scenario and the 

requirements for a passing result are 

provided below: 

• LVS—The SV encounters a stopped 

POV directly in front of it on a straight 

road. The SV is moving at 40.2 kph (25 

mph) and the POV (i.e., the SSV) is 

stationary. The SV throttle is released 

within 500 ms after the SV issues an 

FCW. To pass this test, the SV speed 

reduction attributable to CIB 

intervention must be ≥ 15.8 kph (9.8 

mph). See Figure 1 for a scenario 

diagram. 

• LVD—The SV encounters a POV 

slowing with constant deceleration 

directly in front of it on a straight road. 

The SV and POV are both driven at 56.3 

kph (35 mph) with an initial headway 

of 13.8 m (45.3 ft.). The POV then 

decelerates, braking at a constant 

deceleration of 0.3g in front of the SV, 

after which the SV throttle is released 

within 500 ms after the SV issues an 

FCW. To pass this test, the SV speed 

reduction attributable to CIB 

intervention must be ≥ 16.9 kph (10.5 

mph). See Figure 2 for a scenario 

diagram. 

• LVM—The SV encounters a slowermoving POV directly in front of it on a 

straight road. In the first test, the SV and 

POV are driven on a straight road at a 

constant speed of 40.2 kph (25 mph) 

and 16.1 kph (10 mph), respectively. In 

the second test, the SV and POV are 

driven at a constant speed of 72.4 kph 

(45 mph) and 32.2 kph (20 mph), 

respectively. In both tests, the SV 

throttle is released within 500 ms after 

the SV issues an FCW. To pass the first 

test, the SV must not contact the POV. 

To pass the second test, the SV speed 

reduction attributable to CIB 

intervention must be ≥ 15.8 kph (9.8 

mph). See Figure 3 for a scenario 

diagram. 

• STP test (to assess false positive 

suppression)—The SV is driven towards 

a steel trench plate at 40.2 kph (25 mph) 

in one test and 72.4 kph (45 mph) in the 

other test. If an FCW is issued, the SV 

throttle is released within 500 ms of the 

alert. If no FCW is issued, the throttle 

is not released until the test’s validity 

period (the time when all test 

specifications and tolerances must be 

satisfied) has passed. To pass these 

tests, the SV must not achieve a peak 

deceleration equal to or greater than 

0.5g at any time during its approach to 

the steel trench plate. See Figure 4 for 

a scenario diagram. 

To pass NCAP’s CIB system 

performance criteria, the SV must pass 

at least five out of seven trials for each 

of the six test conditions. 


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Subject Vehicle Steel Trench Plate 

-------------------------------------------------· 

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Figure 4: Steel Trench Plate (STP) False Positive Scenario 
Federal Register / Vol. 89, No. 232 / Tuesday, December 3, 2024 / Notices 95931 

54Wang, J.-S. (2019, March), Target crash 

population for crash avoidance technologies in 

passenger vehicles (Report No. DOT HS 812 653), 

Washington, DC: National Highway Traffic Safety 

Administration. 

55NHTSA notes that the target crash populations 

reported for the LVS, LVD, and LVM scenarios 

encompass all related real-world rear-end crashes 

(where the light vehicle is making a critical action) 

that could potentially be addressed by a DBS 

system. As such, the target crash populations for 

each crash scenario reflect crashes exhibiting 

variations in vehicle overlap, roadway curvature, 

environmental conditions, etc.; target crash 

populations were not reduced to align exactly with 

those represented by NCAP’s LVS, LVD, and LVM 

test scenarios. 

56Swanson, E., Foderaro, F., Yanagisawa, M., 

Najm, W.G., & Azeredo, P. (2019, August), Statistics 

of light-vehicle pre-crash scenarios based on 2011– 

2015 national crash data (Report No. DOT HS 812 

745), Washington, DC: National Highway Traffic 

Safety Administration. 

57NHTSA notes that throughout this notice, all 

crash statistics cited from Report No. DOT HS 812 

745 encompass those where the light vehicle made 

the critical action (e.g., losing control, departing 

road, changing lanes, striking, maneuvering, etc.). 

58For rear-end crashes, posted speed limit was 

unknown or not reported for 2 percent of fatal 

crashes and 11 percent of injurious crashes. 

59For rear-end crashes, roadway alignment was 

unknown or not reported for 1 percent of fatal 

crashes and 3 percent of injurious crashes. 

60For rear-end crashes, roadway grade was 

unknown or not reported for 4 percent of fatal 

crashes and 18 percent of injurious crashes. 

61The Agency also asserts that its 

recommendation of AEB systems (i.e., CIB and DBS) 

that meet NCAP performance criteria on its website 

since the 2018 model year has further encouraged 

adoption of these technologies. 

62 Insurance Institute for Highway Safety (2016, 

March 17), U.S. DOT and IIHS announce historic 

commitment of 20 automakers to make automatic 

emergency braking standard on new vehicles, 

https://www.iihs.org/news/detail/u-s-dot-and-iihsannounce-historic-commitment-of-20-automakersto-make-automatic-emergency-braking-standardon-new-vehicles. 

63To achieve an advanced rating in IIHS’ front 

crash prevention track tests, a vehicle’s AEB system 

must show a speed reduction of at least 16.1 kph 

(10 mph) in either IIHS’s 19.3 or 40.2 kph (12 or 

25 mph) tests, or a speed reduction of 8.0 kph (5 

mph) in both tests. https://www.iihs.org/news/ 

detail/u-s-dot-and-iihs-announce-historiccommitment-of-20-automakers-to-make-automaticemergency-braking-standard-on-new-vehicles. 

64National Highway Traffic Safety 

Administration (2019, December 17), NHTSA 

announces update to historic AEB commitment by 

20 automakers, https://www.nhtsa.gov/pressreleases/nhtsa-announces-update-historic-aebcommitment-20-automakers. 

65NCAP’s CIB test protocol requires a speed 

reduction of at least 15.8 kph (9.8 mph) in the 

program’s 40 kph (24.9 mph) LVS test. However, 

the voluntary commitment allows a vehicle to 

comply with the memorandum for a speed 

reduction of 8.0 kph (5 mph) in IIHS’s 19.3 and 40.2 

kph (12 and 25 mph) LVS tests. 

66 In this instance, ‘‘vehicles’’ refers to the total 

number of vehicles in the 2021 fleet, and not the 

total number of vehicle models for that year. 

67These values assume a 50 percent take rate for 

vehicles having optional equipment. 

68No contact was assumed if the test vehicle did 

not contact the POV in five or more of the seven 

required trial runs. 

C. Linking Current FCW and AEB Test 

Scenarios With Real-World Crashes 

NCAP’s FCW and AEB test scenarios 

are directly related to real-world crash 

data. From its analysis of 2011 to 2015 

Fatality Analysis Reporting System 

(FARS) and National Automotive 

Sampling System General Estimate 

System (GES) data, the Agency found 

that crashes analogous to the LVS test 

scenario, where a struck vehicle was 

stopped at the time of impact, occurred 

in 65 percent of the rear-end crashes 

studied.54 55 The LVD scenario, in which 

the struck vehicle was decelerating at 

the time of impact, occurred in 22 

percent of the rear-end crashes, and the 

LVM scenario, in which the struck 

vehicle was moving at a constant, but 

slower, speed compared to the striking 

vehicle at impact, occurred in 10 

percent of the rear-end crashes. 

Collectively, these test scenarios 

represented 97 percent of rear-end 

crashes. 

With respect to test speed, in its 

independent review of the 2011–2015 

FARS and GES data sets, the John A. 

Volpe National Transportation Systems 

Center (Volpe) concluded that, when 

posted speed limit was known, 2 

percent of fatal rear-end crashes and 6 

percent of all rear-end crashes occurred 

on roadways with posted speed limits of 

40.2 kph (25 mph) or less.56 57 58 Eleven 

percent of fatal rear-end crashes and 33 

percent of all rear-end crashes where 

posted speed limit was known occurred 

on roads with posted speeds of 56.3 kph 

(35 mph) or less. For posted speeds of 

72.4 kph (45 mph) or less, Volpe found 

the comparable statistics to be 29 

percent and 70 percent, respectively. 

Roadway alignment and grade for the 

current FCW and AEB test scenarios are 

also comparable to those found where 

real-world rear-end crashes occur. 

NHTSA’s LVS, LVD, and LVM 

procedures are to be performed on 

straight, level roads. In its review of 

2011–2015 FARS and GES data sets, for 

rear-end crashes where roadway 

alignment was known, Volpe found that 

95 percent of both fatal and injurious 

crashes occurred on a straight 

roadway.59 For rear-end crashes where 

roadway grade was known, 77 percent 

of fatal crashes and 84 percent of 

crashes with injuries occurred on level 

roads.60

1. AEB Installation Rates, Effectiveness, 

and Research Tests 

a. AEB Installation Rates 

When NHTSA’s CIB test scenarios 

were developed, relatively few vehicles 

were equipped with this technology; 

those that were equipped had systems 

with limited capabilities. Since then, 

fitment rates for CIB systems have 

increased significantly due in part to a 

voluntary industry commitment made 

in March 2016.61 Per this commitment, 

20 vehicle manufacturers, representing 

more than 99 percent of light motor 

vehicle sales in the U.S., voluntarily 

committed to make FCW and CIB 

standard on virtually all light-duty 

vehicles with a gross vehicle weight 

rating (GVWR) of 3,855.5 kg (8,500 

pounds) or less beginning no later than 

September 1, 2022, and all trucks with 

a GVWR between 3,856.0 and 4,535.9 kg 

(8,501 and 10,000 pounds) beginning no 

later than September 1, 2025.62

Conforming vehicles were required to be 

equipped with (1) an AEB system that 

earned at least an ‘‘advanced’’ rating 

from IIHS in its then-current front crash 

prevention track LVS tests and (2) an 

FCW system that met the performance 

requirements specified in two of 

NCAP’s current three FCW test 

scenarios, LVD and LVM.63 By 2019, 

participating manufacturers had 

equipped 75 percent of their new 

vehicle fleet with AEB,64 and for model 

year 2023 vehicles, approximately 91 

percent of the fleet was equipped with 

FCW and AEB systems as standard 

equipment. 

As fitment increased, the sensor 

technology for CIB systems also 

advanced significantly. In 2017, many 

systems were not designed to meet the 

voluntary commitment thresholds, 

whereas by 2021, most vehicles with 

FCW and CIB systems could pass all 

relevant NCAP test scenarios, most of 

which are more stringent than those 

included in the voluntary agreement.65

In its RFC, NHTSA noted that the 

original equipment manufacturer 

(OEM)-reported pass rate for NCAP’s 

FCW and CIB tests for model year 2021 

vehicles 66 equipped with these 

technologies, and for which 

manufacturers submitted data, was 89 

percent and 70 percent, respectively.67

Furthermore, NHTSA mentioned that 

only 63 percent of model year 2017 

vehicles avoided contacting the POV for 

at least five out of seven of the required 

runs in the LVS CIB scenario during the 

Agency’s testing, whereas 100 percent of 

model year 2021 vehicles were able to 

repeatedly avoid contact when tested.68

It should be noted that a speed 

reduction of 15.8 kph (9.8 mph) for at 

least five out of seven trial runs is 

currently required to pass NCAP’s CIB 

LVS test, not complete crash avoidance. 

For the model year 2023 vehicle fleet, 

the OEM-reported pass rate for the 

Agency’s FCW test was 98 percent of 

equipped vehicles, and 86 percent for 


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95932 Federal Register / Vol. 89, No. 232 / Tuesday, December 3, 2024 / Notices 

69Per Wang, J.-S. (2019, March), Target crash 

population for crash avoidance technologies in 

passenger vehicles (Report No. DOT HS 812 653), 

Washington, DC: National Highway Traffic Safety 

Administration, there were 1,099,868 LVS, 374,624 

LVD, and 174,217 LVM crashes annually. 

Furthermore, there were 561,842 MAIS 1–5 injuries 

resulting from the LVS crash scenario, 196,731 for 

LVD, and 97,402 for LVM. The LVS scenario also 

had the second highest number of fatalities. 

70The Agency desired to use the GVT in lieu of 

the SSV for its higher speed testing because, given 

its material properties, the GVT significantly 

reduced the potential for damage to the testing 

equipment and test vehicles. 

71Test reports related to NHTSA’s CIB 

characterization testing can be found in the docket 

for the March 2022 RFC notice. 

72Swanson, E., Foderaro, F., Yanagisawa, M., 

Najm, W.G., & Azeredo, P. (2019, August), Statistics 

of light-vehicle pre-crash scenarios based on 2011– 

2015 national crash data (Report No. DOT HS 812 

745), Washington, DC: National Highway Traffic 

Safety Administration. 

73 Gregory M. Fitch, Myra Blanco, Justin F. 

Morgan, Jeanne C. Rice, Amy Wharton, Walter W. 

Wierwille, and Richard J. Hanowski (2010, April) 

Human Performance Evaluation of Light Vehicle 

Brake Assist Systems: Final Report (Report No. DOT 

HS 811 251) Washington, DC: National Highway 

Traffic Safety Administration, p. 13 and p. 101. 

74Two vehicles avoided contact with the POV in 

four out of five trials. 

75Leslie, A.J., Kiefer, R.J., Meitzner, M.R., & 

Flannagan, C.A. (2019, September), Analysis of the 

field effectiveness of General Motors production 

active safety and advanced headlighting systems, 

The University of Michigan Transportation 

the CIB test. In the Agency’s model year 

2023 CIB testing, all vehicles avoided 

contacting the POV test device for at 

least five out of seven runs, and thus 

received credit for passing performance. 

For the FCW assessments, only one 

vehicle model failed to provide a 

passing performance for the LVS and 

LVD scenarios. 

b. Model Year 2019 and 2020 Research 

Testing 

As NHTSA noted in its March 2022 

RFC, research testing conducted for a 

sample of model year 2019 and 2020 

vehicles from various manufacturers 

also confirmed advancement of CIB 

system capabilities in recent years. The 

goal of this testing was to characterize 

the performance of then-current CIB 

systems and evaluate the technology’s 

future potential for the new model 

years’ vehicle fleet. For this purpose, the 

Agency chose to focus testing on 

NCAP’s LVS and LVD test scenarios, as 

its review of the 2011–2015 FARS and 

GES rear-end crash data sets showed 

that LVS and LVD rear-end scenarios 

resulted in the highest number of 

crashes and MAIS 1–5 injuries.69

NHTSA conducted testing for each 

scenario in accordance with NCAP’s 

current CIB test procedure. These tests 

were then repeated using an ABD GVT 

as the surrogate vehicle in lieu of the 

SSV to verify that little to no change in 

performance would result.70 The 

Agency also performed additional tests 

for each scenario using the GVT to 

assess how specific procedural changes 

(i.e., increases in test speed and POV 

deceleration magnitude) affected CIB 

system performance.71

For the additional LVS tests, the 

Agency incrementally increased the 

vehicle speed from 40.2 to 72.4 kph (25 

to 45 mph) in 8.0 kph (5 mph) 

increments to identify when or if the 

vehicle reached its operational limits 

and/or did not react to the POV ahead. 

When the vehicle’s intervention was 

insufficient (i.e., the SV’s maximum 

(peak) deceleration was less than 0.5g), 

the Agency repeated the test scenario at 

a test speed that was 4.0 kph (2.5 mph) 

lower. This reduced speed was used to 

define the system’s upper capabilities 

for the LVS scenario. 

For the additional LVD tests, the 

Agency evaluated how changes made to 

either the SV and POV speed (72.4 kph 

versus 56.3 kph (45 mph versus 35 

mph)) or POV deceleration magnitude 

(0.5g versus 0.3g) affected CIB 

performance. No changes were made to 

the SV-to-POV headway; it was retained 

at 13.8 m (45.3 ft.). 

The Agency chose to increase the test 

speeds for the scenarios included in its 

CIB characterization study because, in 

its independent analysis of the 2011– 

2015 FARS data set, Volpe found that, 

when the posted speed limit was 

known, approximately 29 percent of 

fatalities and 70 percent of injuries in 

rear-end crashes occurred when the 

posted speed on roadways was 72.4 kph 

(45 mph) or less.72 The additional 

change to increase the POV deceleration 

in the LVD scenario was intended to 

create a more stringent test to address 

situations where the driver of a lead 

vehicle brakes aggressively, causing the 

driver of the following vehicle to have 

even less time to avoid or mitigate the 

crash than had the lead vehicle braking 

been at the 0.3g level presently specified 

in the Agency’s test procedure. Based on 

previous Agency research, when drivers 

need to apply the brakes in a nonemergency situation, they do so by 

decelerating up to approximately 

0.306g, while drivers encountering an 

unexpected obstacle apply the brakes at 

0.48g.73 Further, NHTSA noted that a 

deceleration of 0.5g falls within the 

range of deceleration magnitudes 

prescribed by Euro NCAP in its AEB 

Car-to-Car systems test protocol, Version 

3.0.3, dated April 2021 for the Car-toCar rear braking CCRb scenario. In its 

CCRb test, Euro NCAP specifies POV 

deceleration magnitudes of 2 m/s2 and 

6 m/s2 (approximately 0.2 to 0.6 g) for 

an SV-to-POV headway of 12 m (39.4 ft.) 

and SV test speed of 50 kph (31.1 mph). 

The Agency’s characterization testing 

showed that many vehicles were able to 

repeatedly provide complete crash 

avoidance at higher test speeds and 

generally more aggressive conditions 

than those specified in NCAP’s current 

CIB test procedure. For the 56.3 kph 

(35.0 mph) LVS tests conducted with a 

POV deceleration of 0.3g, seven out of 

the eleven vehicles avoided contact 

with the lead vehicle in every test trial. 

One of the remaining vehicles avoided 

contact in six out of seven test trials and 

the other three vehicles demonstrated 

an average speed reduction that 

exceeded 30.6 kph (19 mph). For the 

72.4 kph (45.0 mph) LVS tests 

conducted with a POV deceleration of 

0.3g, four out of the eleven vehicles 

avoided contact in every test trial and 

two other vehicles avoided contact in all 

but one test trial. Three of the remaining 

vehicles avoided contact in one or two 

test trials, while the two other vehicles 

could not avoid contact but both 

demonstrated an average 21 kph (13 

mph) speed reduction. For the 56.3 kph 

(35.0 mph) LVD tests conducted at 0.5g 

rather than 0.3g, as specified in NCAP’s 

current CIB test procedure, eight 

vehicles demonstrated the ability to 

avoid contact with the lead vehicle in at 

least one trial and three vehicles 

avoided contact in all trials, despite 

having less time to avoid the crash.74

Similarly, when the speed of the SV and 

lead vehicle was increased to 72.4 kph 

(45 mph), nine vehicles demonstrated 

the ability to avoid contact with the lead 

vehicle in at least one test while four 

vehicles avoided contact in all tests. 

One vehicle avoided contact in all lead 

vehicle decelerating trials, including 

both increased speeds and increased 

lead vehicle deceleration. 

Given these findings, the Agency 

concluded that current CIB systems are 

capable of significantly exceeding 

NCAP’s current testing requirements. 

Thus, it is feasible to update the 

program’s CIB test conditions to further 

safety improvements and address a 

greater number of rear-end crashes, 

particularly those which cause a greater 

number of injuries and fatalities in the 

real world. 

c. AEB Effectiveness 

In its March 2022 RFC notice, NHTSA 

discussed findings from several studies 

suggesting that AEB systems (i.e., CIB 

and DBS) have collectively been 

effective in reducing rear-end crashes. 

As noted in the introductory section, 

UMTRI 75 found that AEB systems 


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Federal Register / Vol. 89, No. 232 / Tuesday, December 3, 2024 / Notices 95933 

Research Institute and General Motors LLC, 

UMTRI–2019–6. 

76The AEB systems studied by UMTRI consisted 

of camera-only, radar-only, and fused camera-radar 

AEB systems, the latter two systems of which also 

included adaptive cruise control functionality. 

77Cicchino, J.B. (2017, February), Effectiveness of 

forward collision warning and autonomous 

emergency braking systems in reducing front-to-rear 

crash rates, Accident Analysis and Prevention, 2017 

Feb;99(Pt A):142–152, https://doi.org/10.1016/ 

j.aap.2016.11.009. 

78Cicchino, J.B. & Zuby, D.S. (2019, August), 

Characteristics of rear-end crashes involving 

passenger vehicles with automatic emergency 

braking, Traffic Injury Prevention, 2019, VOL. 20, 

NO. S1, S112–S118 https://doi.org/10.1080/ 

15389588.2019.1576172. 

79Foundation brake system means all 

components of the service braking system of a 

motor vehicle intended for the transfer of braking 

application force from the operator to the wheels of 

a vehicle. See 49 CFR 579.4. 

80https://www.regulations.gov/document/ 

NHTSA-2023-0021-0005. 

81 In the Pass Through + STP test, the SV 

approaches a large steel plate positioned 

longitudinally on the test surface in the forward 

path of the SV. Two stationary lead vehicles are 

located to the left and right of the STP in the SV 

forward path. The SV is driven over the STP, 

between the two lead vehicles. 

produced an estimated 46 percent 

reduction in applicable rear-end crashes 

when combined with a forward 

collision alert, which alone showed 

only a 21 percent reduction.76 Similarly, 

in a 2017 study, IIHS found that rearend collisions decreased by 50 percent 

for vehicles equipped with AEB and 

FCW.77 Furthermore, a 2019 study 

conducted by IIHS 78 suggested that the 

increasing effectiveness of AEB 

technology in certain crash situations, 

particularly those evaluated by NCAP 

and other consumer information 

programs, is changing the rear-end crash 

problem. 

While these studies suggest that AEB 

systems (i.e., CIB and DBS) have 

collectively been effective in reducing 

rear-end crashes, NHTSA stated in its 

March 2022 notice that it was not clear 

how effective each of these systems is 

independently, or whether their 

individual effectiveness may change for 

certain crash scenarios, environmental 

conditions, or driver factors (e.g., poor 

judgement, distraction, etc.). The 

Agency also stated it is not aware of any 

studies of current-generation AEB 

systems that have determined the extent 

to which CIB and DBS individually 

contribute to crash reduction. Since 

NHTSA could not differentiate between 

the individual effectiveness of CIB and 

DBS systems, it tentatively concluded 

that NCAP should continue to assess 

CIB and DBS system performance 

individually and therefore retain DBS 

assessments. NHTSA explained that this 

approach would ensure vehicles would 

not suppress AEB operation in 

situations where the driver applies the 

vehicle’s foundation brakes.79 However, 

as discussed later, the Agency also 

sought comment on removing the DBS 

test conditions from NCAP entirely in 

an effort to reduce test burden. 

The Agency did not perform DBS 

testing as part of its characterization 

study to evaluate system performance 

capabilities beyond what is currently 

required in NCAP’s respective test 

procedure. However, DBS systems have 

historically been shown to impart 

additional braking beyond that afforded 

by CIB systems. NHTSA has observed 

complete crash avoidance in DBS tests 

but only speed reduction in the 

equivalent CIB tests conducted for the 

same vehicle models. Therefore, it was 

expected that DBS performance should 

typically be as good as, if not better 

than, CIB performance. NHTSA believed 

that it was fitting to align the proposed 

CIB and DBS evaluations for the 

assessed situations, since doing so 

would allow the Agency to evaluate 

whether a vehicle’s DBS system would 

provide sufficient supplemental braking 

if the driver brakes but additional 

braking is warranted. To verify that 

equivalent performance requirements 

and criteria proposed for CIB would also 

be appropriate for DBS, NHTSA 

planned research tests for model year 

2021 and 2022 vehicles. 

d. Model Year 2021 and 2022 Research 

Testing 

In accordance with its plans 

expressed in the March 2022 RFC, 

NHTSA conducted a series of AEB 

research tests in 2022 to further analyze 

current fleet performance.80 This 

testing, which involved 12 model year 

2021 and 2022 light vehicles, included 

CIB and DBS testing in a variety of CIB 

and DBS test conditions. The goal of 

this research was to evaluate NHTSA’s 

AEB proposals (found in subsequent 

sections) and to gain further knowledge 

regarding the capabilities of the current 

vehicle fleet. 

Both CIB and DBS tests were 

conducted in the LVS, LVM, LVD, and 

STP false positive scenarios. 

Additionally, NHTSA conducted two 

other false positive test scenarios as part 

of this research: a ‘‘Pass Through’’ test, 

in which the SV approaches two 

stationary lead vehicles located to the 

left and right of the SV forward path, 

and ‘‘Pass Through + STP’’ test, which 

is a combination of the STP and Pass 

Through scenarios.81 See Table 11 for 

the nominal test parameters used in this 

series of research tests. The ABD GVT 

Revision G, secured to a GST robotic 

platform (or carrier), was used as the 

POV for the model year 2021 and 2022 

research testing. 

TABLE 11—NOMINAL TEST PARAMETERS FOR MODEL YEAR 2021 AND 2022 RESEARCH TESTING

Test scenario 

Test speeds (kph (mph)) Headway 

(m (ft.)) 

POV 

decel. (g) CIB DBS 

SV POV 

Lead Vehicle Stopped (LVS) ............... 10, 40, 50, 60, 70, 80 (6.2, 24.9, 31.1, 

37.3, 43.5, 49.7).

0 ........................................ .................... ✓ ....................

70, 80, 90, 100 (43.5, 49.7, 55.9, 

62.1).

0 ........................................ .................... .................... ✓ 

Lead Vehicle Moving (LVM) ................ 40, 50, 60, 70, 80 (24.9, 31.1, 37.3, 

43.5, 49.7).

20 (12.4) ........................................ .................... ✓ ....................

70, 80, 90, 100 (43.5, 49.7, 55.9, 

62.1).

20 (12.4) ........................................ .................... .................... ✓ 

Lead Vehicle Decelerating (LVD) ........ 50 (31.1) .............................................. 50 (31.1) 12, 40 (39.4, 131.2) 0.4, 0.5 ✓ ✓ 

80 (49.7) .............................................. 80 (49.7) 12, 40 (39.4, 131.2) 0.4, 0.5 ✓ ✓ 

Steel Trench Plate (STP) .................... 80 (49.7) .............................................. .................... ........................................ .................... ✓ ✓ 

Pass Through ...................................... 80 (49.7) .............................................. 0 ........................................ .................... ✓ ✓ 

Pass Through + Steel Trench Plate .... 80 (49.7) .............................................. 0 ........................................ .................... ✓ ✓ 

For the LVS and LVM test series, SV 

speed was increased from lowest to 

highest. One initial trial was conducted 

per test speed. If no SV-to-POV contact 

was observed, the next highest SV speed 

was run. However, if SV-to-POV contact 


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95934 Federal Register / Vol. 89, No. 232 / Tuesday, December 3, 2024 / Notices 

82Cicchino, J.B., & Zuby, D.S. (2019, August), 

Characteristics of rear-end crashes involving 

passenger vehicles with automatic emergency 

braking, Traffic Injury Prevention, 2019, VOL. 20, 

NO. S1, S112–S118, https://doi.org/10.1080/ 

15389588.2019.1576172. 

occurred and the SV speed at the time 

of impact was less than or equal to 50 

percent of the initial SV speed, up to 

four additional (repeated) trials were 

performed at the same SV speed. If two 

additional SV-to-POV impacts were 

observed during the repeat sequence, 

the test series was terminated. 

Furthermore, if the SV speed at the time 

of impact was greater than 50 percent of 

the initial SV speed during the initial 

trial, no repeat runs were performed; 

testing for that scenario was terminated. 

For the LVD test series, testing 

proceeded in a similar manner. The SV 

speed was increased from lowest to 

highest, and POV deceleration was 

iteratively increased from 0.4g to 0.5g 

for a given speed combination and 

headway. Relevant outcomes of this 

research are detailed throughout the 

applicable sections of this notice. 

D. NHTSA’s Proposals, Summary of 

Comments, Response to Comments, and 

Agency Decisions 

1. AEB 

a. Forward Collision Prevention 

Technologies Inclusion in General 

Many commenters, including the 

NTSB, Bosch, HMNA, and NADA, 

expressed support for the Agency’s 

proposed updates for NCAP’s AEB 

testing. Additional proponents, such as 

the Advocates and QuantivRisk, Inc., 

cited the need for increased test 

stringency to realize additional safety 

benefits. In this vein, NTSB specifically 

asked NHTSA to ‘‘strive for the 

performance we want the systems to be 

able to reach, not merely evaluate the 

current capabilities of the systems.’’ 

Auto Innovators expressed a need for 

consistency between changes to NCAP 

and those planned for AEB standards. 

Other respondents, such as MEMA, 

appreciated the Agency’s attempts to 

focus resources on emerging trends and 

harmonize its AEB test procedures with 

those used by European New Car 

Assessment Programme (Euro NCAP) 

and other consumer information 

programs. Toyota also supported the 

Agency’s attempts at shared global 

assessments but recommended that 

NHTSA select (1) tests that can 

adequately ensure performance across a 

range of conditions to improve overall 

test efficiency and (2) performance 

criteria that reflect real-world benefits. 

Citing rising fatalities, several 

commenters requested that the Agency 

consider AEB test additions for cyclists 

and motorcyclists, while others 

mentioned current AEB system 

limitations, such as systems’ inability to 

detect cyclists and other vulnerable road 

users (VRUs) at higher speeds and in 

low light and inclement weather. 

b. AEB Test Procedure Changes, 

Including Higher Speeds and POV 

Deceleration Magnitude for LVD Test; 

and Removal of DBS Tests and Only 

High-Speed DBS Assessments 

NHTSA proposed harmonizing many 

aspects of changes to NCAP’s CIB and 

DBS procedures with Euro NCAP’s AEB 

Car-to-Car systems test protocol. The 

Agency reasoned this approach was 

most appropriate based on requirements 

of the BIL. The Agency also argued that 

it would be beneficial to standardize the 

current AEB test specifications with 

other consumer information programs, 

as doing so would allow the Agency and 

vehicle manufacturers to focus 

resources on emerging trends for rearend crashes as AEB-equipped vehicles 

become more abundant in the fleet.82

NHTSA also noted it would consider 

making additional updates to its AEB 

test evaluation as the rear-end crash 

problem evolves. 

The updated CIB and DBS tests 

proposed in the 2022 RFC are detailed 

below for each test scenario. Tables 12 

and 13 summarize the proposed test 

scenarios and conditions. 

TABLE 12—CIB TEST SCENARIOS AND CONDITIONS PROPOSED IN THE 2022 RFC 

Test 

scenario 

SV speed 

(kph (mph)) 

POV speed 

(kph (mph)) 

POV 

headway 

(m (ft.)) 

POV 

deceleration 

(g) 

Requirement to pass 

LVS ............. 40 (24.9) 

50 (31.1) 

60 (37.3) 

70 (43.5) 

80 (49.7) 

0 

0 

0 

0 

0 

n/a 

n/a 

n/a 

n/a 

n/a 

n/a 

n/a 

n/a 

n/a 

n/a 

(1) No SV-to-POV contact on first trial; 

OR 

(2) Any SV-to-POV contact where the relative velocity between the SV and POV is ≤ 

50% of initial SV speed 

AND 

No SV-to-POV contact in 3 out of 5 total trials. 

LVM ............ 40 (24.9) 20 (12.4) n/a n/a 

50 (31.1) 20 (12.4) n/a n/a 

60 (37.3) 20 (12.4) n/a n/a 

70 (43.5) 20 (12.4) n/a n/a 

80 (49.7) 20 (12.4) n/a n/a 

LVD * .......... 50 (31.1) 50 (31.1) 12 (39.4) 0.5 

60 (37.3) 60 (37.3) 12 (39.4) 0.5 

70 (43.5) 70 (43.5) 12 (39.4) 0.5 

80 (49.7) 80 (49.7) 12 (39.4) 0.5 

* For LVD, NHTSA requested comment on whether at least five of seven trials should be required for vehicles whose contact velocity is ≤50 percent of the initial velocity, whether a 40 m headway should be included, and whether NHTSA should employ a 0.6g POV deceleration in lieu of 0.5g. 

TABLE 13—DBS TEST SCENARIOS AND CONDITIONS* PROPOSED IN THE 2022 RFC 

Test 

scenario 

SV speed 

(kph (mph)) 

POV speed 

(kph (mph)) 

POV 

headway 

(m (ft.)) 

POV 

deceleration 

(g) 

Requirement to pass 

LVS ** ......... 70 (43.5) 

80 (49.7) 

0 

0 

n/a 

n/a 

n/a 

n/a 

(1) No SV-to-POV contact on first trial; 

OR 

(2) Any SV-to-POV contact where the relative velocity between the SV and POV is ≤50% 

of initial SV speed 

AND 

No SV-to-POV contact in 3 out of 5 total trials. 

LVM ** ......... 70 (43.5) 20 (12.4) n/a n/a 

80 (49.7) 20 (12.4) n/a n/a 


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83European New Car Assessment Programme 

(Euro NCAP) (April 2021), Test Protocol—AEB Carto-Car systems, Version 3.0.3. See section 8.2.3. 

84European New Car Assessment Programme 

(Euro NCAP) (April 2021), Test Protocol—AEB Carto-Car systems, Version 3.0.3. See section 8.2.4. 

TABLE 13—DBS TEST SCENARIOS AND CONDITIONS* PROPOSED IN THE 2022 RFC—Continued 

Test 

scenario 

SV speed 

(kph (mph)) 

POV speed 

(kph (mph)) 

POV 

headway 

(m (ft.)) 

POV 

deceleration 

(g) 

Requirement to pass 

LVD *** ........ 70 (43.5) 70 (43.5) 12 (39.4) 0.5 

80 (49.7) 80 (49.7) 12 (39.4) 0.5 

* For all DBS conditions, NHTSA requested comment on removal of all DBS test conditions. 

** For LVS and LVM, NHTSA requested comment on the additional inclusion of 40, 50, and 60 kph (24.9, 31.1, and 37.3 mph). 

*** For LVD, NHTSA requested comment on the additional inclusion of 50 and/or 60 kph (31.1 and/or 37.3 mph) SV/POV speeds or only 70 and 80 kph (43.5 and 

49.7 mph) (if they were adopted for CIB as well). NHTSA also requested comment on whether at least five of seven trials should be required to satisfy the performance requirement for vehicles whose relative velocity at contact is ≤50 percent of the initial SV speed, whether 40 m headway should be included, and whether 

NHTSA should employ 0.6g POV deceleration in lieu of 0.5g. 

Crash Imminent Braking (CIB) 

Lead Vehicle Stopped (LVS) 

Currently, NCAP’s CIB LVS test is 

conducted at a speed of 40.2 kph (25 

mph). In its upgrade proposal, the 

Agency recommended assessing CIB 

system performance over a range of test 

speeds for this test scenario. 

Specifically, NHTSA proposed a 

minimum SV test speed of 40 kph (24.9 

mph) (similar to that currently specified 

in NHTSA’s CIB test procedure) and a 

maximum SV test speed of 80 kph (49.7 

mph). NHTSA also proposed increasing 

the SV test speed in 10 kph (6.2 mph) 

increments from the minimum test 

speed to the maximum test speed for the 

LVS assessment, performing one trial 

per speed. To achieve a passing result 

for each speed, NHTSA proposed that 

the test trial must be valid (all test 

specifications and tolerances satisfied), 

and the SV must not contact the POV. 

Further, the Agency proposed that it 

would conduct four additional trials for 

any specific test speed that resulted in 

a test failure (i.e., contact) as long as the 

SV relative velocity at impact was less 

than or equal to 50 percent of the initial 

SV speed. For these five trials (i.e., one 

failed trial and four additional trials), 

NHTSA proposed that the SV must 

avoid contact with the POV for at least 

three trials to pass the test condition 

(i.e., combination of test scenario and 

test speed). 

In justifying its recommendation to 

incorporate higher test speeds for the 

LVS scenario, in addition to Volpe’s 

real-world data analysis, which 

illustrated the safety need, the Agency 

indicated its CIB characterization testing 

demonstrated that several vehicles 

repeatedly afforded full crash avoidance 

(i.e., no contact) at speeds up to 72.4 

kph (45 mph) when subjected to this 

test. Further, NHTSA recognized that 

Euro NCAP’s Car-to-Car Rear stationary 

(CCRs) scenario, which is comparable to 

the Agency’s LVS test, is conducted at 

speeds as high as 80 kph (49.7 mph) in 

the ‘‘AEB only’’ test condition. NHTSA 

reasoned that Euro NCAP’s use of higher 

test speeds suggests higher test speeds 

are, from the perspective of test 

conduct, practicable for NCAP’s LVS 

test as well.83 The Agency believed it 

was appropriate to harmonize with Euro 

NCAP on the maximum LVS test speed 

of 80 kph (49.7 mph), as this should 

better address the higher severity, highspeed crash problem and, in turn, 

further reduce fatalities and serious 

injuries. However, NHTSA did not 

propose to harmonize with Euro NCAP’s 

protocol on the minimum SV test speed. 

Euro NCAP’s CCRs scenario specifies a 

minimum SV speed of 10 kph (6.2 mph) 

for AEB systems, but the Agency stated 

it did not see the need to conduct its 

updated LVS testing at a speed less than 

that which is specified in its existing 

test procedure (40.2 kph (25 mph)). As 

such, a minimum test speed of 40 kph 

(24.9 mph) was proposed instead. 

The Agency sought comment on 

whether the proposed speeds and 

overall assessment approach were 

appropriate for LVS or whether 

alternatives should be considered. 

Lead Vehicle Moving (LVM) 

As mentioned previously, NCAP’s CIB 

test procedure currently includes two 

LVM test conditions: a lower speed 

assessment that specifies an SV speed of 

40.2 kph (25 mph) and POV speed of 

16.1 kph (10 mph), and a higher speed 

assessment that prescribes an SV speed 

of 72.4 kph (45 mph) and POV speed of 

32.2 kph (20 mph). For this NCAP 

update, NHTSA proposed to assess CIB 

system performance over a range of SV 

test speeds for the LVM scenario. 

Similar to its proposal for the LVS 

scenario, NHTSA proposed to 

implement a ‘‘no contact’’ performance 

criterion for the LVM scenario and to 

increase the SV test speed for the LVM 

assessment in 10 kph (6.2 mph) 

increments from a minimum speed of 40 

kph (24.9 mph) to a maximum speed of 

80 kph (49.7 mph), with a POV speed 

of 20 kph (12.4 mph) for every SV test 

speed. The Agency also proposed to 

perform one trial run per speed and four 

additional trials for any specific test 

speed that resulted in a test failure for 

initial runs where the SV had a relative 

velocity at impact less than or equal to 

50 percent of the initial SV speed. 

Similar to its proposal for LVS, the 

Agency proposed that the SV must not 

contact the POV for at least three out of 

the five test trials performed at that 

same speed to pass the LVM test 

condition. 

The Agency noted that the proposed 

minimum SV test speed of 40 kph (24.9 

mph) is nearly equivalent to the speed 

currently specified for its lower speed 

LVM assessment, 40.2 kph (25 mph), 

and the proposed maximum SV test 

speed of 80 kph (49.7 mph) is only 

slightly higher than the speed specified 

for its higher speed LVM assessment, 

72.4 kph (45 mph). Since NCAP’s higher 

speed CIB LVM assessment (conducted 

at an SV speed of 72.4 kph (45 mph) and 

POV speed of 32.2 kph (20 mph)) 

showed that many vehicles were able to 

stop without contacting the POV test 

device for each of the required test 

trials, NHTSA believed it was 

reasonable to raise the SV speed in 

NCAP’s LVM test even though it had not 

performed additional LVM testing as 

part of its characterization study. The 

Agency also noted that Euro NCAP 

performs its Car-to-Car Rear moving 

(CCRm) scenario (which is comparable 

to NCAP’s LVM tests) at speeds as high 

as 80 kph (49.7 mph), further suggesting 

that higher SV test speeds are 

practicable.84 Given this, NHTSA 

believed it was appropriate to 

harmonize with Euro NCAP on the 

maximum SV test speed of 80 kph (49.7 

mph) for the Agency’s LVM test. 

NHTSA reasoned that adopting a higher 

maximum SV test speed than that which 

is currently required in the Agency’s 

CIB procedure should encourage 

improved CIB system performance at 

higher speeds, and thus further reduce 

fatalities and serious injuries. 

Although it proposed to harmonize 

with Euro NCAP’s protocol with respect 

to the maximum SV speed adopted for 


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I I I I I 
95936 Federal Register / Vol. 89, No. 232 / Tuesday, December 3, 2024 / Notices 

85European New Car Assessment Programme 

(Euro NCAP) (April 2021), Test Protocol—AEB Carto-Car systems, Version 3.0.3. See section 8.2.5. 

86The Agency proposed these speeds would each 

be assessed for both 12 and 40 m (39.4 and 131.2 

ft.) headways and POV deceleration magnitudes of 

0.4g and 0.5g. 

87European New Car Assessment Programme 

(Euro NCAP) (), Test Protocol—AEB Car-to-Car 

systems, Version 3.0.3. See section 8.2.5. 

88NHTSA notes that the LVD research tests were 

conducted only for 50 and 80 kph (31.1 and 49.7 

mph) test speeds. 

its LVM test, the Agency did not suggest 

harmonizing with Euro NCAP with 

respect to the minimum required SV test 

speed. Euro NCAP’s CCRm scenario 

specifies a minimum SV test speed of 30 

kph (18.6 mph) for AEB-equipped 

vehicles; however, the Agency did not 

believe there was not a compelling 

reason to perform its updated LVM test 

at a speed that is less than the current 

required test speed (i.e., 40.2 kph (25 

mph)) since most vehicles have been 

able to meet NCAP’s current LVM test 

requirements at 40.2 kph (25 mph) to 

date with a similar POV test speed. 

Accordingly, NHTSA proposed a 

minimum SV test speed of 40 kph (24.9 

mph). 

NHTSA proposed to adopt a POV test 

speed of 20 kph (12.4 mph). The Agency 

noted this POV speed is specified in 

Euro NCAP’s CCRm protocol, and 

therefore adopting this speed for 

NHTSA’s LVM testing seemed 

appropriate since it would further 

support harmonization efforts. 

Comments were requested on whether 

the SV/POV speeds and assessment 

approach proposed for NCAP’s CIB 

LVM tests were appropriate or whether 

alternative speeds or approaches should 

be considered instead. 

Lead Vehicle Decelerating (LVD) 

For the LVD scenario, NHTSA 

proposed to reduce the minimum 

nominal SV and POV test speeds from 

56 kph (34.8 mph), as specified in 

NCAP’s test procedure, to 50 kph (31.1 

mph), as stated in Euro NCAP’s AEB 

Car-to-Car systems test protocol, Version 

3.0.3, dated April 2021 for the Car-toCar rear braking (CCRb) scenario.85 The 

Agency stated that, given additional 

changes proposed for the SV-to-POV 

headway and deceleration magnitude 

for the LVD scenario, the proposed 

reduction in test speed would not lead 

to an overall reduction in test stringency 

or loss of safety benefits. NHTSA 

requested comment on whether this 

proposed test speed change was 

appropriate for NCAP’s LVD testing. 

The Agency also sought comment on 

whether it would be appropriate to 

incorporate additional SV and POV test 

speeds for the LVD test scenario: 60, 70, 

and 80 kph (37.3, 43.5, and 49.7 mph, 

respectively). Similar to the proposed 

CIB LVS and LVM test scenarios, 

NHTSA proposed to concurrently 

increase the SV and POV test speeds in 

10 kph (6.2 mph) increments from the 

minimum test speed to the maximum 

test speed for NCAP’s LVD assessment 

if multiple speeds were adopted. The 

Agency also proposed, as discussed in 

a later section, to perform one trial run 

per speed and four additional trials for 

any specific test speed that resulted in 

a test failure (i.e., SV-to-POV contact) 

where the SV had a relative velocity at 

impact less than or equal to 50 percent 

of the initial SV speed. Like the other 

two CIB test scenarios, the Agency 

proposed the SV must not contact the 

POV for at least three out of the five test 

trials performed at that same speed to 

pass the test condition. Alternatively, 

the Agency sought comment on whether 

testing at only 50 kph (31.1 mph) and 

80 kph (49.7 mph) would be acceptable. 

NHTSA acknowledged in its proposal 

that it had not yet performed LVD 

testing at 80 kph (49.7 mph), mainly due 

to equipment and test track length 

limitations, as this test scenario requires 

that both the SV and POV be travelling 

at the same speed at the onset of the test 

validity period. However, the Agency 

recognized that higher speed tests may 

be warranted. For instance, Volpe’s 

analysis of the 2011–2015 FARS data set 

showed that, when posted speed limit 

was known, the majority of fatal rearend crashes (71 percent) occurred on 

roads with posted speeds exceeding 

72.4 kph (45 mph). Considering the 

braking performance observed during 

the high-speed LVS tests conducted as 

part of its characterization study, the 

Agency noted current vehicles may 

perform well in LVD tests conducted at 

even higher speeds. Additionally, 

NHTSA believed that CIB systems may 

be able to classify POVs more 

confidently in the LVD test compared to 

the LVS test due to the POV’s detected 

motion (i.e., path history). Accordingly, 

NHTSA conducted research to assess 

vehicles’ CIB system performance in the 

LVD test at SV and POV speeds ranging 

from 50 kph (31.1 mph) to 80 kph (49.7 

mph) to determine the feasibility of 

adopting one or more of these speeds for 

this test scenario.86

In its March 2022 RFC notice, NHTSA 

also proposed to reduce the minimum 

nominal SV-to-POV headway of 13.8 m 

(45.3 ft.), currently specified for the LVD 

scenario, to 12 m (39.4 ft.) for the 

proposed test speed of 50 kph (31.1 

mph). Although not assessed as part of 

its CIB characterization testing, the 

Agency asserted this change would not 

only harmonize with Euro NCAP’s 

CCRb scenario with respect to test 

conduct, but also maintain similar 

stringency to NCAP’s current LVD test 

scenario, given the proposed test speed 

reduction from 56 kph (34.8 mph) to 50 

kph (31.1 mph). Euro NCAP also 

specifies an additional SV-to-POV 

headway of 40 m (131.2 ft.); however, 

the Agency did not propose to conduct 

this assessment as part of the RFC, as 

NHTSA suggested there would not be a 

safety benefit in adopting 40 m (131.2 

ft.) as an additional, and presumably 

less stringent, headway. Therefore, the 

Agency did not want to increase the test 

burden unnecessarily. However, the 

Agency indicated that it would assess 

vehicle performance at both 12 and 40 

m (39.4 and 131.2 ft.) headways as part 

of its future research for each of the test 

speeds to be evaluated. The Agency also 

sought public comment on which SV-toPOV headway(s) may be appropriate for 

adoption not only for the proposed test 

speed (i.e., 50 kph (31.1 mph)), but also 

for each of the additional test speeds 

(ranging from 60 kph (37.3 mph) to 80 

kph (49.7 mph)) it planned to evaluate 

and possibly incorporate. 

The last change the Agency proposed 

for the LVD test scenario was increasing 

the POV deceleration magnitude 

currently specified in its CIB test 

procedure from 0.3g to 0.5g. In the 

Agency’s CIB characterization study, 

three vehicles repeatedly afforded full 

crash avoidance (i.e., no contact) for all 

trials when the POV executed a 0.5g 

braking maneuver in the LVD condition 

with an SV test speed of 56.3 kph (35 

mph) and SV-to-POV headway of 13.8 m 

(45.3 ft.), demonstrating that the change 

to POV deceleration for the revised LVD 

test conditions (which also includes a 

slightly lower test speed and slightly 

shorter SV-to-POV headway) is likely 

feasible. The Agency also noted that, in 

Euro NCAP’s AEB Car-to-Car systems 

test protocol, the organization specifies 

POV deceleration magnitudes of 2 m/s2

and 6 m/s2 (approximately 0.2 and 0.6g) 

for its CCRb scenario.87 As such, 

NHTSA reasoned that adopting a 0.5g 

POV deceleration magnitude would be 

practicable. To verify this assumption, 

as part of its research study, NHTSA 

committed to evaluating POV 

deceleration magnitudes of both 0.4 and 

0.5g for the range of test speeds 

considered (i.e., 60, 70, and/or 80 kph 

(37.3, 43.5, and/or 49.7 mph)) for future 

LVD testing.88 The Agency also sought 

comment on what deceleration 

magnitude(s) would be appropriate for 

the proposed test speed (i.e., 50 kph 


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Federal Register / Vol. 89, No. 232 / Tuesday, December 3, 2024 / Notices 95937 

89The GVT is secured to the top of the LPRV. The 

LPRV is responsible for any movement of the GVT 

during test conduct. 

90Fogle, E. E., Arquette, T. E. (TRC), and 

Forkenbrock, G. J. (NHTSA), (2021, May), Traffic 

Jam Assist Draft Test Procedure Performability 

Validation (Report No. DOT HS 812 987), 

Washington, DC: National Highway Traffic Safety 

Administration. 

91From Section 4.1 of DOT HS 812 987: ‘‘POV 

deceleration validity check failures occurred during 

six trials of the eight LVDAD trials performed. Four 

of the seven 0.6 g failures were because the POV 

was unable to achieve the minimum deceleration 

threshold of 0.55 g. The remaining three 0.6 g 

failures were because the POV was unable to 

maintain a minimum average deceleration of at 

least 0.55 g.’’ Here, LVDAD refers to ‘‘Lead Vehicle 

Accelerates, Decelerates, then Decelerates.’’ The 

LVDAD test is a more complex variant of the LVD 

test and was used by NHTSA to perform traffic jam 

assist research. 

92NHTSA’s DBS test procedure currently 

specifies ‘‘no contact’’ as the performance criterion 

for all DBS test conditions, whereas the Agency’s 

CIB test procedure currently requires a specified 

speed reduction for each of the CIB test conditions 

(with the exception of the lower speed LVM 

condition where the POV speed is 16.1 kph (10 

mph) and the SV speed is 40.2 kph (25 mph), which 

requires ‘‘no contact.’’ 

93The Agency notes that for the rear-end precrash scenario group, the driver avoidance 

maneuver was unknown in 25 percent and 54 

percent of the FARS and GES crashes, respectively. 

When excluding cases where a driver avoidance 

maneuver was unknown, the driver made no 

attempt to avoid the crash in 75 percent and 48 

percent of the FARS and GES crashes, respectively. 

Likewise, when a driver’s avoidance maneuver was 

known, the driver braked in 11 percent of FARS 

crashes and 45 percent of GES crashes. 

94National Highway Traffic Safety 

Administration (2012, June), Forward-looking 

advanced braking technologies research report, 

https://www.regulations.gov/document?D=NHTSA2012-0057-0001. 

(31.1 mph)), as well as each of these 

additional test speeds. 

NHTSA did not propose a 0.6g POV 

deceleration magnitude for use in its 

LVD test, even though Euro NCAP 

specifies 0.6g as the maximum POV 

deceleration for its CCRb scenario. In 

proposing 0.5g as the maximum POV 

deceleration in lieu of 0.6g, the Agency 

stated a lower POV deceleration may 

reduce equipment wear, particularly for 

the tires and braking components of the 

POV propulsion system, thus improving 

test efficiency. Specifically, NHTSA 

explained it has observed instances 

where the tires of the low-profile robotic 

vehicle (LPRV) platform 89 used to move 

the GVT developed flat spots while 

performing a braking maneuver similar 

to that specified in the Agency’s CIB 

LVD test 90 but with higher POV 

decelerations. During this testing, 

NHTSA also found it was more difficult 

to achieve and accurately control POV 

deceleration within prescribed 

tolerances when braking maneuvers 

higher than 0.5g were used, even with 

extensive LPRV tuning efforts.91 The 

Agency noted that a deceleration of 0.6g 

is not only very close to the maximum 

braking capability of the LPRV, but also 

very close to the default magnitude used 

by the LPRV during an emergency stop 

(maximum deceleration). However, 

NHTSA acknowledged that newer 

robotic platforms (i.e., robotic carriers) 

offering greater capabilities are now 

becoming available, and they may 

resolve the issues observed in the 

Agency’s testing. Accordingly, NHTSA 

requested comment on whether it may 

now be feasible to adopt a POV 

deceleration magnitude of 0.6g in lieu of 

0.5g, as proposed. 

Dynamic Brake Support (DBS) 

With respect to DBS, the Agency 

proposed to align all test conditions 

(e.g., SV and POV test speed(s), 

headway(s), POV deceleration 

magnitude(s), etc.) for the comparable 

LVD, LVM, and LVS test scenarios with 

those proposed for CIB. Likewise, 

NHTSA proposed a similar performance 

criterion (i.e., no contact) and 

assessment approach as well; when 

applicable, speeds would be increased 

in 10 kph (6.2 mph) increments from the 

minimum test speed to the maximum 

test speed, with one trial performed per 

speed, and four additional trials 

conducted for any specific test speed 

that resulted in a test failure (i.e., 

contact) as long as the SV had a relative 

velocity at impact less than or equal to 

50 percent of the initial SV speed. 

Similar to CIB, the Agency proposed 

that the SV must avoid contact with the 

POV for at least three out of the five test 

trials performed at that same speed to 

pass the test condition (if the vehicle 

fails the initial trial at a given test 

speed). 

Although the Agency had not 

conducted DBS testing as part of its 

characterization study to evaluate 

system performance capabilities beyond 

what is currently required in NCAP’s 

DBS test procedure, NHTSA believed it 

was nonetheless fitting to align the 

proposed CIB and DBS evaluations, as it 

would allow NHTSA to assess whether 

a vehicle’s DBS system will provide 

supplemental braking if the driver 

manually applies a brake pedal input 

but additional braking is warranted to 

afford crash avoidance. Further, the 

Agency noted its CIB and DBS test 

procedures are currently aligned with 

respect to test scenarios, test speeds, 

headways, etc. Differences exist only 

with respect to the use of manual brake 

application (i.e., for the SV in DBS 

testing) and (most) performance 

criteria.92 Therefore, the Agency 

reasoned it would be appropriate to 

adopt the CIB test conditions (i.e., test 

speeds, headways, etc.) for the 

comparable DBS test conditions for 

future testing as well. NHTSA requested 

comments on whether this proposal for 

future DBS testing, including the 

assessment method, was appropriate. 

The Agency also sought comment on 

removing the LVD, LVM, and LVS DBS 

test conditions from NCAP entirely (in 

addition to the false positive test 

conditions, discussed later) to reduce 

test burden and associated costs given 

findings from Volpe’s analysis of the 

2011–2015 FARS and GES data sets and 

other changes NHTSA proposed for its 

CIB assessments. 

Specifically, Volpe found that the 

driver braked in just 8 percent of rearend crashes involving fatalities and in 

20 percent of those crashes involving 

injuries. The study also showed that the 

driver made no attempt to avoid the 

crash (e.g., no braking, steering, 

accelerating) for 56 percent of crashes 

involving fatalities and for 21 percent of 

those involving injuries.93 These 

findings were contrary to those 

documented by NHTSA during a review 

of 2003–2009 National Automotive 

Sampling System Crashworthiness Data 

System data to define the target 

population for rear-end crashes.94 For 

that analysis, the Agency concluded that 

the driver braked in approximately half 

of the crashes and did not brake in the 

other half, which lends merit to 

performing both CIB and DBS tests. The 

Agency believed it was possible the 

brake application rates differed in the 

two studies because of (1) target crash 

population refinements made for 

NHTSA’s original analysis and (2) 

differences in data collection methods 

between the crash databases. For 

instance, high-speed crashes were 

excluded from NHTSA’s target crash 

population review because the AEB 

systems tested at the time had limited 

speed reduction capabilities. 

As previously mentioned, NHTSA 

proposed to adopt a more stringent ‘‘no 

contact’’ performance criterion for each 

of NCAP’s CIB test conditions. The 

Agency’s existing CIB test procedure 

requires a specified speed reduction for 

each of the CIB test conditions (with the 

exception of the lower speed LVM 

condition, which requires ‘‘no contact’’), 

whereas the DBS test procedure 

currently specifies ‘‘no contact’’ as the 

performance criterion for all DBS test 

conditions. The proposed change for 

CIB would effectively align the CIB 

performance requirements with those 

currently specified for DBS, and NHTSA 

questioned whether it was necessary to 

continue performing DBS tests in NCAP 

given public comments previously 


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95Alliance of Automobile Manufacturers (The 

Alliance) merged with Global Automakers in 

January 2020 to create the Alliance for Automotive 

Innovation (Auto Innovators). Both automotive 

industry groups separately submitted comments to 

the December 2015 notice. 96See GM Appendix 1. 

97See footnote 11 of Uhnder response. 

98 Kidd, 2022a. 

99 Kidd, 2022b. 

received. For example, in its comments 

to NCAP’s December 2015 notice, the 

Alliance 95 stated that since crash 

avoidance (i.e., no SV-to-POV contact) is 

the desired outcome for all imminent 

rear-end crash events, if an SV avoids 

contact with the POV in all CIB tests, 

DBS testing should not be necessary. 

The Agency agreed with the Alliance’s 

rationale in principle but questioned 

whether there would be merit to 

ensuring both AEB systems perform as 

designed and help the driver to mitigate 

or prevent the crash. NHTSA 

hypothesized that it may be possible for 

the driver to apply the brakes but with 

a magnitude that does not result in 

achieving the vehicle’s maximum crash 

avoidance potential (i.e., deceleration). 

Further, the Agency explained that, in 

the past, some manufacturers had 

assumed the driver was in control when 

the brake pedal was depressed, and 

designed CIB systems such that 

automatic braking was overridden by 

the driver’s input, even when the 

driver’s braking was insufficient to 

avoid a crash. Based on this reasoning, 

NHTSA explained it was hesitant to 

assume that if a vehicle’s CIB system 

works effectively during testing, its DBS 

system would automatically do so as 

well. 

Thus, as an alternative to removing 

the DBS performance evaluations from 

NCAP entirely (or retaining the LVD, 

LVM, and LVS DBS tests in NCAP, as 

proposed), the Agency concluded that it 

might be more reasonable to conduct 

only LVS and LVM DBS tests in NCAP 

at the highest two test speeds proposed 

for CIB—70 and 80 kph (43.5 and 49.7 

mph, respectively)—to ensure (1) the 

DBS system functions properly at these 

speeds and (2) the SV will not suppress 

AEB operation when the driver applies 

the vehicle’s foundation brakes. The 

Agency further noted that it would also 

consider conducting the DBS LVD test 

at only 70 and 80 kph (43.5 and 49.7 

mph, respectively) if it decided to adopt 

those same higher test speeds for the 

CIB LVD test. Comments were requested 

on this alternative proposal and whether 

an alternative assessment method would 

be more appropriate if any or all of the 

DBS test scenarios were conducted only 

at the two highest test speeds. 

Summary of Comments 

Regarding NHTSA’s AEB Proposal, In 

General 

Several commenters, including BMW, 

FCA, and Honda, supported the 

Agency’s proposal for CIB and DBS with 

respect to SV and POV speeds, headway 

distances, and POV deceleration 

magnitudes. FCA stated that the 

proposal was appropriate because it 

reflects current system capabilities and 

real-world crashes. With the exception 

of suggested changes for the LVD 

scenario, discussed later, Tesla also 

generally agreed with the Agency’s 

proposal with respect to test speeds, 

headway, and deceleration magnitudes 

for CIB testing and the general intent to 

harmonize with Euro NCAP test 

protocols. Specifically, Tesla supported 

conducting LVS and LVM scenarios at 

test speeds ranging from 40 to 80 kph 

(24.9 and 49.7 mph) with 10 kph (6.2 

mph) increments, as proposed. Auto 

Innovators also generally agreed with 

the proposed test requirements but 

suggested the Agency harmonize with 

Euro NCAP and conduct CIB testing up 

to 50 kph (31.1 mph) and DBS testing 

at speeds over 50 kph (31.1 mph). 

Like Tesla, Advocates and Bosch also 

supported generally harmonizing the 

Agency’s CIB testing with that 

performed by Euro NCAP, but with 

small variations. Advocates supported 

aligning the LVM and LVS POV and SV 

speeds with those used by Euro NCAP 

but did not support the Agency’s 

justification for not aligning minimum 

test speeds for these two scenarios with 

those prescribed by Euro NCAP (10 kph, 

or 6.2 mph) as being sufficient. Bosch 

also mentioned harmonization with 

respect to test speeds but suggested the 

Agency should further investigate 

whether there is merit to increasing test 

speeds to assess AEB systems. 

Conversely, GM opposed any change 

to the test conditions prescribed in the 

Agency’s current CIB test procedure. 

The automaker stated that the current 

AEB test speeds show significant realworld safety benefits 96 and, as 

documented in DOT HS 811 521A, 

‘‘Objective Tests for Automatic Crash 

Imminent Braking (CIB) Systems,’’ the 

current test parameters are ‘‘wellsupported by field crash scenarios most 

relevant to these features and associated 

with the highest societal harm, as 

measured by Functional Years Lost.’’ 

Other commenters suggested that the 

Agency remove certain test conditions. 

Auto Innovators suggested that the 

Agency remove one of the two original 

LVM scenarios, preferably the lower 

speed condition (i.e., SV and POV 

speeds of 40 and 16 kph (25 and 10 

mph), respectively), since real-world 

data shows only 2 percent of fatalities 

and 6 percent of injuries occur on roads 

having posted speed limits of 40 kph (25 

mph) or less. Similarly, Toyota stated 

that the Agency should adopt only the 

number of test conditions sufficient to 

communicate accurate performance 

information to consumers. The 

automaker suggested that, if testing only 

at a certain speed would ensure 

performance for a large speed range, 

then that approach was acceptable for 

testing. 

With respect to other procedural 

considerations, Subaru recommended 

that NHTSA adopt a speed increment of 

20 kph (12.4 mph) in lieu of 10 kph (6.2 

mph) for LVM testing. A few other 

respondents also generally supported 

the test parameters, but suggested slight 

modifications, which are addressed later 

in this section. 

Adopt Higher AEB Test Speeds Than 

Those Proposed 

State Farm, IIHS, and Uhnder 

supported CIB and DBS testing at higher 

speeds, stating that such speeds better 

reflect real-world driving conditions. 

Uhnder supported adoption of test 

speeds that exceed 88.5 kph (55 mph), 

citing a May 2022 study from IIHS 

finding nearly 70 percent of fatal rearend crashes occurred when the speed 

limit was 88.5 kph (55 mph) or higher.97

Similarly, IIHS noted that nearly 80 

percent of police-reported rear-end 

crashes occurred on roads having speed 

limits ranging from 48.3 to 104.6 kph 

(30 to 65 mph),98 and the speed of the 

striking vehicle was more than 40 kph 

(24.9 mph), even on roads with speed 

limits of 40.2 kph (25 mph).99

Adasky, NTSB, and CAS also favored 

higher speed AEB assessments than 

those proposed. CAS asserted that 

NHTSA should conduct CIB tests at the 

highest speeds possible to still afford 

safe testing so that consumers may 

identify vehicles offering superior CIB 

performance at each test speed. 

Similarly, NTSB encouraged NHTSA to 

consider more challenging test speeds to 

drive desired (i.e., ideal) system 

performance instead of testing to current 

system capabilities. Finally, Rivian also 

suggested adopting higher speeds for 

DBS tests than those proposed if the 

Agency continued DBS testing in the 

future. 


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100See case study included in Toyota’s 

comments. 

Test Speeds and Headway for the LVD 

Test Scenario Specifically 

Several commenters favored adopting 

AEB test speeds up to 80 kph (49.7 

mph) for the LVD test scenario, with 

BMW and Honda stating that these test 

speeds were appropriate since they were 

supported by crash data. 

Tesla, along with Subaru, 

recommended conducting LVD 

scenarios at 50 kph (31.1 mph), as 

proposed (similar to Euro NCAP), and 

also at 80 kph (49.7 mph), as suggested 

by NHTSA. Subaru added that, if a test 

failure occurs at 80 kph (49.7 mph), the 

test speed should then be reduced by 10 

kph (6.2 mph). Advocates favored 

harmonization with Euro NCAP with 

respect to test speed, headway, and 

deceleration for the LVD scenario, but 

preferred NHTSA’s alternative proposal 

of adopting multiple higher test speeds 

(above 50 kph (31.1 mph)), suggesting 

NHTSA should also include a ‘‘range of 

test speeds’’ based on crash data and the 

Agency’s testing. 

Toyota encouraged NHTSA to 

conduct additional feasibility studies 

and research, particularly for the LVD 

test scenario, to: (1) resolve possible 

GVT stability issues; (2) study the 

possible conflict with human driver 

steering avoidance maneuver timing; 

and (3) research the effectiveness of 

FCW and DBS based on the physical 

limitations imposed by the proposed 

LVD DBS test condition, and, 

considering driver reaction times, 

determine whether such higher-speed 

testing is feasible and appropriate before 

modifying the AEB test conditions. With 

respect to the first request, Toyota noted 

the Agency’s statement that it has not 

conducted CIB/DBS LVD testing at 80 

kph (49.7 mph) because of equipment 

and test track length limitations. 

Regarding its second point, the 

automaker asserted that the time 

required to steer to avoid a collision at 

higher speeds is less than the time 

required to brake, and that by imposing 

the suggested high speed CIB test 

conditions, the Agency may create a 

challenging ‘braking’ situation that 

could interfere with a driver’s ability to 

avoid the crash by steering instead. 

Lastly, Toyota voiced concern that the 

SV and POV dynamics for DBS LVD 

testing at higher speeds may pose 

physical limitations.100 More 

specifically, for speeds of 50 kph (31.1 

mph) and greater, the manufacturer 

asserted that, given the (constant) 

headway prescribed, the time (i.e., TTC) 

required to activate the brake to avoid 

impact, and the proposed brake 

application timing of 1.0 s after issuance 

of the FCW, it is possible the FCW 

would have to be issued before the POV 

test device begins to decelerate in the 

DBS test for the SV to avoid contact 

with the POV. Toyota was supportive of 

DBS testing at higher speeds for the LVS 

test scenario. 

Intel shared Toyota’s concerns about 

the LVD DBS tests, explaining the 

proposed headway (12 m (39.4 ft.)) may 

be too small given a POV deceleration 

of 0.5 to 0.6g, such that it may not be 

possible to issue the FCW early enough 

to achieve brake activation one second 

after the issuance of the FCW as NHTSA 

proposed for the test procedure. Intel 

also cautioned the Agency that it should 

ensure it is feasible for test labs to 

conduct LVD tests at the proposed 

higher speeds considering the GVT 

platform experiences performance 

degradation at high speeds. Intel further 

noted many automakers limit speed 

reductions to approximately 60 kph 

(37.3 mph) per Automotive Safety 

Integrity Level (ASIL) considerations. 

Auto Innovators did not support the 

Agency’s adoption of test speeds 

exceeding the capabilities afforded by 

current systems for the LVD test 

condition because it may induce false 

positives under real-world driving 

conditions, which may in turn 

discourage AEB use. The group, like 

Toyota, also cautioned that the 

proposed high-speed testing may cause 

unexpected interactions between the SV 

and POV during testing. Auto 

Innovators recommended that the 

Agency consider the proposed changes 

for CIB and DBS for future program 

updates to (1) allow additional time to 

investigate the field relevance of the 

proposed changes for both technologies 

and (2) provide sufficient time for 

system capabilities to improve. 

To better align with Euro NCAP 

testing, Intel suggested that LVD testing 

should be limited to 50 kph (31.1 mph) 

and should be performed only for 

vehicles equipped with both AEB and 

FCW. HATCI recommended that the 

Agency harmonize with the test speeds 

prescribed in Euro NCAP’s protocol for 

the LVD test scenario if it ultimately 

adopts higher test speeds, and asked 

that the SV-to-POV headway be 

increased for each higher speed test 

condition based on field-representative 

distances or TTCs. Subaru 

recommended that the Agency maintain 

vehicle headway in LVD testing at a 

spacing equivalent to 1.0 second 

(instead of 12 m (39.4 ft.), as proposed) 

regardless of test speed. FCA also 

favored higher speed assessments for 

the LVD test scenario. However, FCA 

stated that the SV-to-POV headway 

should be adjusted for each speed to 

reflect a 0.9 second following distance, 

asserting this following distance is 

typical of real-world driving. 

POV Deceleration Magnitude for LVD 

Test Scenario 

Most commenters addressing this 

issue favored a 0.5g POV deceleration 

for the LVD CIB test instead of 0.6g, 

with TRC citing issues with 

repeatability when attempting to tune 

the GVT braking system to operate at a 

deceleration greater than 0.5g. Although 

it acknowledged that new robotic 

platforms make tuning easier, TRC also 

suggested that they are expensive and 

require modification of existing 

equipment before they can be utilized. 

BMW also cited robotic platform 

operational limits and tire wear as 

reasons not to adopt a 0.6g POV 

deceleration requirement. HATCI 

favored a 0.5g deceleration magnitude 

because of proven repeatability and 

minimal equipment damage. The 

commenter recommended that the 

Agency increase the vehicle headway if 

it chooses to adopt a 0.6g POV 

deceleration instead. 

GM and Auto Innovators supported a 

0.5g deceleration, asserting that this is a 

‘‘common’’ deceleration level (based on 

crash data reviewed by NHTSA) and 

therefore ‘‘realistic.’’ Both commenters 

mentioned that a 0.6g deceleration has 

not been shown to induce differences in 

vehicle performance, but can cause 

problems with test equipment (based on 

experience in conducting Euro NCAP 

tests at 6 m/s2). In a similar vein to the 

repeatability concerns mentioned by 

others, GM also noted that China NCAP 

no longer generally performs LVD tests 

(and other consumer groups are 

expected to follow suit) because they are 

difficult to conduct and test results for 

a given vehicle model are often widely 

variable. 

A few commenters expressed 

conditional support for the higher POV 

deceleration. Specifically, Honda and 

Auto Innovators offered support for 

adoption of a 0.6g deceleration if crash 

data indicates such a limit is more 

representative of driver braking in realworld crashes. Auto Innovators added 

that the Agency must also ensure testing 

tolerances. FCA suggested that a 0.6g 

deceleration may be acceptable if 

NHTSA wanted to ‘‘reduce validation 

effort.’’ 

Intel expressed support for adopting a 

0.6g deceleration criterion for the LVD 

CIB test to harmonize with other entities 

and regulations and thus reduce test 

burden. The company stated that, 

considering the tolerance currently 

prescribed for the POV deceleration, the 


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difference between 0.5g and 0.6g is 

small. Bosch also supported adoption of 

a 0.6g deceleration magnitude, as did 

Tesla. However, Tesla suggested that in 

lieu of a single POV deceleration of 0.5 

or 0.6g, as proposed, the Agency should 

adopt deceleration magnitudes of –2 m/ 

s2 and –6 m/s2 (approximately 0.2 and 

0.6g), respectively, for each test speed to 

harmonize with Euro NCAP. Advocates 

shared this opinion. 

Agree With Removal of DBS Tests 

MEMA, Subaru, and HATCI agreed 

with the Agency’s proposal to remove 

the DBS test scenarios from NCAP’s 

AEB test matrix, with the latter 

commenter suggesting that CIB and DBS 

functionality may overlap at certain 

speeds such that DBS functionality 

would be redundant when CIB is 

activated. HATCI therefore suggested 

that, if the Agency decided to continue 

conducting separate DBS assessments in 

NCAP, such tests should only be 

performed when a vehicle exhibits a test 

failure during CIB testing for that 

condition, as this would reduce test 

burden. Rivian remarked that the DBS 

testing was unnecessary because a 

vehicle’s CIB system will activate and 

slow the vehicle when the braking 

imparted by DBS is insufficient. Subaru 

recommended removal or replacement 

of any ADAS test that currently has a 

high rate of passing results if adoption 

rates for the related ADAS technology 

are also high. 

Retain Some or All DBS Tests 

Several commenters expressed that 

the Agency should continue to conduct 

DBS assessments in NCAP because DBS 

affords additional safety benefits 

compared to CIB. ZF Group favored 

retaining the DBS tests to ensure that 

vehicles continue to be equipped with 

DBS, noting that DBS systems ‘‘can react 

earlier in critical situations.’’ Similarly, 

CAS asserted that DBS ‘‘can provide 

additional safety margin.’’ 

Other commenters recommended that 

NHTSA continue DBS testing to ensure 

system functionality. Advocates, GM, 

and Auto Innovators suggested the 

Agency should (Advocates and GM), or 

could (Auto Innovators), continue to 

conduct DBS tests to ensure that brake 

pedal application does not override AEB 

system functionality in general. NTSB 

also agreed that DBS functionality 

should be verified and supported 

NHTSA’s alternative proposal to retain 

DBS testing in NCAP and conduct LVM 

and LVS testing at higher speeds (70 

and 80 kph (43.5 and 49.7 mph)). 

GM and Auto Innovators also 

recommended other options centered on 

performing DBS tests only at certain 

speeds that NHTSA could adopt to 

reduce the burden of DBS testing. GM 

noted that China NCAP performs CIB 

tests at lower speeds and DBS tests at 

higher speeds. The automaker suggested 

that for speeds higher than 40 kph (24.9 

mph) the Agency could alternate 

between CIB and DBS testing. Auto 

Innovators stated that DBS testing 

would be unnecessary in situations 

where the CIB system provides 

complete avoidance in all tests, noting 

that the Agency could simply assume 

DBS performance and apply points for 

both systems equally. Auto Innovators 

also stated that each assessed test speed 

should afford equal weighting for both 

CIB and DBS, noting it should not be the 

case that one test speed carries twice the 

weight simply because both systems are 

assessed at that speed, whereas another 

test speed carries less weight because 

only one of the two systems is assessed 

at that speed. Both GM and Auto 

Innovators noted, similar to HATCI, that 

NHTSA could conduct CIB tests until 

the system can no longer provide full 

avoidance and then begin DBS testing 

for the next subsequent higher test 

speed. If the CIB system was able to 

provide complete avoidance at all test 

speeds, then the commenters suggested 

that DBS testing could be repeated for 

only the maximum test speed to ensure 

system functionality. GM also noted that 

for 2023 Euro NCAP removed the DBS 

tests for LVM and LVD from their 

assessment and going forward it will 

only perform the DBS test for the LVS 

scenario. Finally, Auto Innovators 

encouraged the Agency to reduce the 

number of test scenarios and evaluate 

FCW during DBS testing (i.e., record the 

time of the FCW) to further reduce test 

burden. 

Like other commenters’ suggestions, 

FCA and Intel recommended that the 

Agency continue to perform DBS tests 

in NCAP for higher test speeds where 

the CIB system does not afford full crash 

avoidance, with Intel suggesting that it 

may be appropriate to start the DBS tests 

at 60 kph (37.3 mph) to harmonize with 

Euro NCAP. IDIADA also suggested that 

the Agency only perform higher speed 

DBS tests. Similarly, Toyota, like the 

NTSB, was supportive of the Agency 

conducting LVS and LVM DBS tests at 

only the highest test speeds proposed 

for CIB—70 and 80 kph (43.5 and 49.7 

mph), respectfully. However, Toyota did 

not support conducting the LVD DBS 

test at 80 kph (49.7 mph) since NHTSA 

stated that it had not conducted testing 

at this speed due to equipment and test 

track limitations. Intel expressed similar 

concerns, stating that manufacturers 

may not be able to issue the FCW early 

enough to achieve brake activation one 

second after the issuance of the FCW as 

NHTSA proposed for the LVD tests. 

Unlike those commenters who 

expressed that it was sufficient for the 

Agency to only conduct high-speed DBS 

assessments or alternate CIB and DBS 

assessments for incremental speeds, 

Honda stated that it is most appropriate 

to conduct CIB and DBS tests at the 

same test speeds. Honda asserted that 

evaluating DBS performance only at 

higher test speeds may skew 

performance ratings (similar to what 

Auto Innovators stated) and not 

accurately convey the real-world safety 

benefits DBS provides at lower test 

speeds. Since CIB and DBS address 

different safety needs (i.e., the driver is 

either not responsive, or responsive, 

respectively, to an imminent collision), 

the automaker indicated that it is 

imperative to ensure ratings reflect the 

benefits afforded by both technologies. 

Accordingly, Honda, like Auto 

Innovators, suggested that if the Agency 

moves forward with such an approach, 

vehicles should be awarded credit for 

lower speed DBS tests as well (even 

though they would only be tested for 

CIB and not DBS) if the vehicle received 

passing results for the CIB system at the 

lower test speeds. Honda asserted this 

credit would be appropriate, noting that 

DBS systems should afford equivalent or 

higher performance than CIB systems 

when tested at the same speeds. Bosch 

similarly responded that it would be 

appropriate to cover the entire speed 

range by performing one test per 

scenario and incrementing speeds for 

each separate scenario by 10 kph (6.2 

mph) if NHTSA decided to continue to 

perform separate DBS assessments and 

if there are benefits to increasing both 

CIB and DBS test speeds. CAS also 

noted that if the Agency imposed higher 

test speeds for LVD CIB assessments, 

those same test speeds should be used 

to assess DBS. The group stated that 

DBS activation was highly likely for the 

LVD scenario and all technologies that 

may contribute to a given scenario/crash 

outcome should be assessed. Likewise, 

Tesla asserted that DBS testing should 

not be reserved only for higher-speed 

assessments and should be conducted 

using the same test specifications 

(speed, headway, and POV deceleration) 

as the corresponding CIB tests. 

Advocates encouraged NHTSA to 

select the appropriate number of tests 

and test speeds to ensure acceptable 

performance across a range of 

conditions, including those that would 

be expected during real-world driving. 


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101Swanson, E., Foderaro, F., Yanagisawa, M., 

Najm, W.G., & Azeredo, P. (2019, August), Statistics 

of light-vehicle pre-crash scenarios based on 2011– 

2015 national crash data (Report No. DOT HS 812 

745), Washington, DC: National Highway Traffic 

Safety Administration. 

102 Data provided is from all rear-end FARS and 

GES crashes, including cases where posted speed 

limit was unknown. 

103European New Car Assessment Programme 

(Euro NCAP) (December 2023), Test Protocol—AEB 

Car-to-Car systems, Version 4.3. See section 8.2.2.2. 

Response to Comments and Agency 

Decisions 

NHTSA’s decision regarding CIB and 

DBS testing specifics can be found in 

the following sections as well as in 

Tables 12 and 13. 

CIB Test Speeds for the LVS Test 

Scenario 

NHTSA will proceed with assessing 

CIB performance in NCAP’s LVS 

scenario using the proposed SV test 

speeds and increments. The Agency will 

initiate the LVS test series at the lowest 

vehicle test speed, 40 kph (24.9 mph), 

and test speeds will increase in 

increments of 10 kph (6.2 mph) as each 

test condition’s criteria are met (i.e., no 

SV-to-POV contact is observed), up to 

and including the 80 kph (49.7 mph) 

test condition. 

Although several commenters, 

including Advocates, recommended that 

the Agency set the minimum LVS test 

speed to 10 kph (6.2 mph) to harmonize 

with Euro NCAP, the Agency asserts a 

40 kph (24.9 mph) minimum LVS test 

speed is appropriate for NCAP testing. 

As noted in Auto Innovators’ comments 

to the March 2022 RFC notice, Volpe’s 

review of 2011–2015 crash data sets 

showed that, for rear-end crashes, only 

2 percent of fatalities and 6 percent of 

injuries occurred on roadways with 

posted speed limits of 40.2 kph (25 

mph) or less.101 102 It is most 

appropriate, at this time, to allocate 

resources for the flagship consumer 

information program to performing tests 

representing rear-end crashes that are 

more likely to induce injuries or 

fatalities instead of those that are more 

likely to cause only property damage. 

NHTSA has chosen to set the 

uppermost SV test speed for CIB LVS 

testing at 80 kph (49.7 mph). A few 

commenters, such as GM, requested that 

the Agency not make any changes to the 

current AEB test conditions, including 

the test speeds, stating that the current 

conditions already provide significant 

real-world safety benefits. However, 

most commenters supported NHTSA’s 

proposal to increase test speeds, 

including for the LVS test scenario, and 

several commenters even suggested 

adopting higher test speeds, with 

recommended maximums ranging from 

88.5 to 104.6 kph (55 to 65 mph). The 

Agency notes that its recent research 

testing showed CIB tests up to 80 kph 

(49.7 mph) are practicable; however, 

there is a particular need for 

improvement in CIB performance at 

vehicle test speeds above 60 kph (37.3 

mph). In NHTSA’s model year 2021– 

2022 CIB LVS research test series, out of 

12 test vehicles, only three achieved full 

avoidance at 70 kph (43.5 mph) and two 

achieved full avoidance at 80 kph (49.7 

mph). Given these results, establishing a 

maximum test speed of 80 kph (49.7 

mph) for NHTSA’s CIB LVS testing is 

currently appropriate. Further, as 

NHTSA recognized in its 2022 RFC 

notice, by adopting a maximum LVS test 

speed of 80 kph (49.7 mph), the Agency 

will harmonize with Euro NCAP’s upper 

test speed limit for its CCRs scenario, 

which is analogous to NHTSA’s LVS 

test scenario. Ensuring robust AEB 

system performance at 80 kph (49.7 

mph) also allows the Agency to better 

target the high severity, high-speed 

crash problem identified in Volpe’s realworld data analysis, further mitigating 

serious injuries and fatalities. For future 

iterations of the testing program, the 

Agency may choose to increase this 

upper test speed, as several commenters 

suggested, based on further real-world 

data collection and analysis, future 

research, the assurance of test 

practicability, and other factors. 

As vehicles meet the criteria (i.e., no 

SV-to-POV contact is observed) for 

passing each LVS test condition, SV test 

speeds will increase in 10 kph (6.2 mph) 

increments. Thus, LVS tests may be 

conducted for SV test speeds of 40 kph, 

50 kph, 60 kph, 70 kph, and 80 kph 

(24.9 mph, 31.1 mph, 37.3 mph, 43.5 

mph, and 49.7 mph), respectively, 

depending on the vehicle’s performance 

at each speed. Should a test failure 

occur at any of these speeds, defined as 

SV-to-POV contact during the single 

trial performed at that respective speed, 

the test laboratory will discontinue the 

LVS test series. By using 10 kph (6.2 

mph) increments, the Agency can 

minimize potential damage to the test 

vehicle and vehicle test device as test 

speeds and potential impact energy 

increase. 

CIB Test Speeds for the LVM Test 

Scenario 

NHTSA will adopt the same SV test 

speeds for LVM testing that it is 

adopting for LVS testing: a minimum 

speed of 40 kph (24.9 mph) with speed 

increases in increments of 10 kph (6.2 

mph), up to and including 80 kph (49.7 

mph), as test vehicles meet criteria (i.e., 

no contact) for passing each LVM 

condition. This approach results in 

potential SV test speeds of 40 kph, 50 

kph, 60 kph, 70 kph, and 80 kph (24.9 

mph, 31.1 mph, 37.3 mph, 43.5 mph, 

and 49.7 mph), respectively, depending 

on vehicle performance at each speed. 

For the lead vehicle, the POV speed will 

be 20 kph (12.4 mph) regardless of SV 

test speed. 

NHTSA’s rationale for adopting the 

LVS minimum and maximum SV test 

speeds and speed increments also 

pertains to LVM testing. The Agency 

asserts the selected speeds relate well to 

the rear-end crash problem and should 

thus improve real-world safety. Also, 

LVM testing at the selected speeds is 

possible. Not only are the SV speeds 

selected already assessed by Euro NCAP 

in its CCRm test,103 but also, during 

model year 2021–2022 research testing, 

NHTSA found that vehicle models 

performed more favorably throughout 

the battery of test speeds in its CIB LVM 

test series than in its LVS test series. 

Only one vehicle did not achieve full 

avoidance in the 70 kph (43.5 mph) 

condition, and an additional three did 

not fully avoid the POV in the 80 kph 

(49.7 mph) condition. The rest of the 

vehicles were able to fully avoid SV-toPOV impact in every CIB LVM test 

condition. Because the lead vehicle is 

moving in LVM tests, the SV’s speed 

relative to the POV is lower than in the 

LVS scenario for any given test speed. 

Further, the current NCAP protocol 

specifies similar minimum SV speeds 

and slightly lower maximum SV speeds 

(40.2 kph (25 mph) and 72.4 kph (45 

mph)), so it is possible manufacturers 

have already designed their vehicles’ 

CIB systems to mitigate such crashes. 

Adopting a POV speed of 20 kph (12.4 

mph) is appropriate for the LVM tests. 

As noted in the March 2022 RFC notice, 

Euro NCAP’s CCRm protocol specifies 

this POV speed, offering another 

opportunity for NCAP to harmonize 

with other consumer information 

programs. 

Although Subaru recommended that 

the Agency adopt a speed increment of 

20 kph (12.4 mph) in lieu of 10 kph (6.2 

mph) for NCAP’s LVM testing, 

explaining that this speed increment 

would be ‘‘adequate for system 

evaluation,’’ conducting an additional 

two test runs at 50 and 70 kph (31.1 and 

43.5 mph) in addition to 40, 60, and 80 

kph (24.9, 37.3, and 49.7 mph) should 

not add significantly to the test burden. 

Therefore, the Agency does not see a 

reason to deviate for the LVM test 

scenario from the 10 kph (6.2 mph) 

speed increment adopted for the other 

AEB test scenarios. 


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104European New Car Assessment Programme 

(Euro NCAP) (December 2023), Test Protocol—AEB 

Car-to-Car systems, Version 4.3. See section 8.2.2.3. 

105The Agency additionally notes that Euro 

NCAP awards points for vehicles equipped with 

Emergency Steering Support (ESS) systems that 

assist a driver in safely maneuvering around an 

obstacle in select scenarios. See TB037, https://

cdn.euroncap.com/media/68587/tb-037-essassessment-v10.pdf. 

106Emergency Steer and Brake Assist—A 

Systematic Approach for System Integration of Two 

Complementary Driver Assistance Systems (Eckert, 

Continental AG, Paper Number 11–0111), https://

www-hesv.nhtsa.dot.gov/Proceedings/22/files/ 

22ESV-000111.pdf. 

107Swanson, E., Foderaro, F., Yanagisawa, M., 

Najm, W.G., & Azeredo, P. (2019, August), Statistics 

of light-vehicle pre-crash scenarios based on 2011– 

2015 national crash data (Report No. DOT HS 812 

745), Washington, DC: National Highway Traffic 

Safety Administration. 

CIB Test Speeds for the LVD Test 

Scenario 

For the LVD CIB test scenario, the 

Agency will conduct tests using two SV/ 

POV test speeds only: 50 kph (31.1 

mph) and 80 kph (49.7 mph). NHTSA 

chose these speeds for several reasons. 

First, Euro NCAP specifies a 50 kph 

(31.1 mph) test speed for its CCRb 

scenario,104 and adopting this speed 

allows the Agency to harmonize its 

testing in this regard. Adopting an 80 

kph (49.7 mph) uppermost test speed 

also aligns with the highest speed 

NHTSA is adopting for NCAP’s LVM 

and LVS test scenarios. 

Second, in NHTSA’s model year 

2021–2022 research testing series, 

vehicles performed reasonably well for 

the 50 kph (31.1 mph) LVD test 

conditions. Half of the tested models 

met all the requirements for every test 

condition (i.e., varying headways and 

POV decelerations). However, the 80 

kph (49.7 mph) LVD test conditions 

proved more difficult, with SV-to-POV 

contact observed in most vehicle trials. 

Varying responses in vehicle braking 

systems and/or AEB algorithms may 

have contributed to the performance 

differences seen at 50 kph (31.1 mph) 

versus 80 kph (49.7 mph). However, one 

vehicle was able to pass all test criteria 

for the 80 kph (49.7 mph) LVD test 

condition, thus proving that robust AEB 

performance at this higher test speed is 

feasible. This vehicle was a popular 

model with a high sales volume, and the 

Agency has not observed an increase in 

reports of false activations in the field. 

Thus, it is NHTSA’s view that Auto 

Innovators’ concern that encouraging 

swift innovation will result in many 

false positive activations is unfounded, 

at least up to the maximum speed the 

Agency has chosen to adopt at this time. 

Third, NHTSA has confirmed that its 

initial concern (which was also 

expressed by Toyota) regarding safety 

considerations and equipment 

limitations when running higher-speed 

LVD tests was unwarranted for speeds 

up to 80 kph (49.7 mph). The Agency’s 

recent research for model year 2021– 

2022 vehicles showed that it is feasible 

to conduct CIB LVD testing at 80 kph 

(49.7 mph) safely. Further, neither test 

track limitations nor achieving the 

higher GVT speeds were found to be 

problematic during this testing. 

Finally, as mentioned previously, 

NHTSA notes that real-world fatality 

and injury data highlights a safety need 

for testing at higher speeds, further 

suggesting that adopting an 80 kph (49.7 

mph) upper test speed for the LVD test 

scenario is warranted. While Euro 

NCAP’s CCRb test scenario specifies a 

single test speed of 50 kph (31.1 mph), 

and Intel requested that NHTSA adopt 

only this speed for the LVD scenario, 

adopting 80 kph (49.7 mph) in addition 

to 50 kph (31.1 mph) is appropriate. 

This decision also aligns with the 

recommendation made by other 

commenters, including Tesla and 

Subaru. 

NHTSA acknowledges Subaru’s 

recommendation that the Agency 

should perform an additional test at 70 

kph (43.5 mph) if the SV contacted the 

POV during the 80 kph (49.7 mph) test 

to identify the vehicle’s CIB 

performance threshold. Other 

commenters stated that NHTSA should 

test a range of speeds for the LVD tests, 

like the range being adopted for LVM 

and LVS scenarios. However, the initial 

speed conditions for the LVD scenario 

are not as critical to the outcome as 

other test parameters, such as headway 

and POV deceleration, since the SV and 

POV speeds are initially the same. 

Therefore, the Agency has decided to 

use two discrete speeds to evaluate LVD 

performance instead of speed 

increments but, as detailed in the next 

sub-section, will vary the headway and 

POV deceleration magnitude assessed 

for each speed. The use of two speeds 

is expected to ensure system robustness 

while limiting test burden. 

NHTSA also acknowledges Toyota’s 

comments that, in some high-speed 

cases, steering away from the impending 

crash may be preferable to remaining in 

the same travel lane and fully braking, 

since the time required to steer away 

would be less than the time required to 

fully stop.105 That said, the timing 

necessary to steer away from a crash 

rather than brake is not the only factor 

that should be considered; vehicle 

dynamics, traffic conditions, and other 

traffic participants all influence the 

possibility and advisability of a steering 

avoidance maneuver. Steering to avoid 

a crash with a lead vehicle could cause 

the subject vehicle to either depart the 

road, collide with a vehicle in the 

adjacent lane, or on an undivided twolane road, causing a head-on frontal 

crash. As such, the situations in which 

an evasive steering maneuver to avoid a 

crash would likely be the preferable 

response would be under limited 

circumstances, since there must be 

sufficient space in a lane or on the 

shoulder adjacent to the subject 

vehicle’s lane that the subject vehicle 

may move to, and the driver must have 

the ability to safely maneuver a vehicle 

at such a high speed. Further, it is 

unreasonable to assume that a driver 

who is inattentive until moments before 

a crash will reengage and be able to 

perform a safe steering maneuver that 

would not jeopardize the safety of 

others in the surrounding area or 

themselves. 

Research also shows drivers are not 

prone to initiate steering alone to avoid 

a surprise obstacle in front of them in 

the roadway in an emergency 

situation.106 Instead, they either brake, 

or brake and steer. When drivers were 

presented with a surprise obstacle 

catapulted from the side (which 

typically would invoke a steering 

response) at a TTC of 1.5 seconds, with 

the adjacent lane free of obstacles such 

that the drivers had the opportunity to 

avoid a collision by steering alone, 43 

percent of research participants 

attempted to avoid the obstacle by 

braking alone. The other 57 percent of 

participants tried to avoid a collision by 

braking and steering, while no 

participant tried to avoid contact by 

steering alone. Only as the TTC 

increased (i.e., above 2.0 seconds) did 

drivers feel comfortable attempting to 

avoid the obstacle by steering alone. At 

a TTC of 2.0 seconds, 46 percent of 

participants tried to avoid by braking 

alone, 38 percent tried to avoid by 

braking and steering, and 15 percent 

tried to avoid by steering alone, while 

at a TTC of 2.5 seconds, 72 percent of 

participants tried to avoid by braking 

only, 14 percent tried to avoid by 

braking and steering, and 14 percent 

tried to avoid by steering alone. These 

findings further reinforce the Agency’s 

assertion that braking in lane is 

appropriate at the speeds NCAP will 

test. 

The Agency also notes that in its data 

analysis, for those rear-end crashes 

where the driver’s avoidance maneuver 

was known, Volpe found the driver 

made no attempt to avoid the crash for 

75 percent of crashes involving fatalities 

and 48 percent of crashes involving 

injuries.107 108 Therefore, initiating 


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Federal Register / Vol. 89, No. 232 / Tuesday, December 3, 2024 / Notices 95943 

108The SV driver’s avoidance maneuver was 

unknown for 25 percent of fatal rear-end crashes 

and 54 percent of rear-end crashes with policereported injuries. 

109Note that most of the vehicles in this test 

series did not undergo CIB LVD testing at 80 kph 

(49.7 mph) and 0.5g POV deceleration. Thus, 0.4g 

POV deceleration data was used. 

110The Agency notes that testing with a 12 m 

(39.4 ft.) headway and a POV deceleration of 0.5g 

roughly corresponds to the deceleration necessary 

to comply with the minimum stopping distance 

required in FMVSS No. 135, ‘‘Light vehicle brake 

systems.’’ 

111Fitch, G.M., Blanco, M., Morgan, J.F., Rice, 

J.C., Wharton, A., Wierwille, W.W., & Hanowski, 

R.J. (2010, April) Human Performance Evaluation of 

Light Vehicle Brake Assist Systems: Final Report 

(Report No. DOT HS 811 251) Washington, DC: 

National Highway Traffic Safety Administration, p. 

13 and p. 101. 

steering (which would require driver 

engagement) during an AEB test would 

not address this large portion of crashes 

resulting in injuries and fatalities. Given 

the findings from these studies, the 

Agency’s current AEB test requirement 

for braking in the absence of steering is 

appropriate. However, this is not to say 

that steering must be suppressed in 

crash-imminent situations. 

CIB Headway for the LVD Test Scenario 

NHTSA plans to adopt the 12 m (39.4 

ft.) and 40 m (131.2 ft.) headway 

conditions proposed for both the 50 kph 

(31.1 mph) and 80 kph (49.7 mph) LVD 

CIB tests. The Agency’s model year 

2021–2022 testing demonstrated that no 

contact performance is practicable for 

both headways, even at the highest test 

speed (i.e., 80 kph (49.7 mph)) and most 

stringent POV deceleration proposed 

(i.e., 0.5g). One of the twelve test 

vehicles was able to achieve no contact 

performance at 80 kph (49.7 mph) with 

an initial headway of 12 m and lead 

vehicle deceleration of 0.5g. This same 

vehicle, in addition to a second model, 

was also able to meet the test 

requirements at the same test speed for 

a headway of 40 m and POV 

deceleration of 0.5g. For an SV test 

speed of 50 kph (31.1 mph) and 0.5g 

POV deceleration, all but one of the 

twelve vehicles tested avoided contact 

with the POV for the 40 m headway and 

six of the twelve vehicles provided 

passing performance for the 12 m 

headway. 

NHTSA previously stated that 

adopting multiple headways in the LVD 

CIB test to assess CIB system 

performance would unnecessarily 

increase test burden because longer 

headways should result in less stringent 

test conditions compared to shorter 

headways. However, the Agency’s 

recent model year 2021–2022 research 

test findings contradicted this assertion. 

Specifically, greater relative speed 

reduction was not always observed for 

the longer assessed headway (40 m 

(131.2 ft.)) compared to the shorter 

headway (12 m (39.4 ft.)), as the Agency 

had expected. When assessing vehicles 

at 50 kph (31.1 mph) with a POV 

deceleration of 0.5g, one vehicle 

experienced greater relative speed 

reduction during the shorter headway 

(12 m (39.4 ft.)) test than during the 

longer headway (40 m (131.2 ft.) test. 

For LVD CIB tests completed at 80 kph 

(49.7 mph) and 0.4g POV deceleration, 

six vehicle models performed better in 

the shorter headway test compared to 

the longer headway test.109 Thus, the 

Agency now reasons that assessments 

using both headways—the 12 m (39.4 

ft.) condition proposed by NHTSA and 

the 40 m (131.2 ft.) condition required 

by Euro NCAP in its CCRb test—are 

necessary for NCAP testing (in addition 

to the two adopted test speeds) to assess 

CIB performance in the LVD test 

scenario. 

The Agency notes that HATCI 

requested NHTSA increase headways 

for higher-speed testing based on fieldrepresentative distances. Alternatively, 

it and other commenters recommended 

that NHTSA adjust headways based on 

test speed to achieve specific times-tocollision, suggesting these would be 

more representative of real-world 

driving. Such changes are not necessary, 

since results from NHTSA’s recent 

research demonstrate it is possible to 

achieve full avoidance across both short 

and long headways, even at the highest 

speed and highest POV deceleration for 

the CIB LVD tests. Further, while 

maintaining a 12 m (39.4 ft.) headway 

at an 80 kph (49.7 mph) travelling speed 

is uncomfortably close and more likely 

to result in a crash imminent situation, 

it is reflective of the real-world driving 

habits of some individuals. In such 

situations, it will be difficult, even for 

an attentive driver, to react quickly 

enough to avoid a crash, especially with 

a lead vehicle braking above 0.3g. As 

such, it is imperative to ensure vehicles 

respond quickly and appropriately in 

such instances. Performing CIB tests in 

NCAP with an 80 kph (49.7 mph) test 

speed and 12 m (39.4 ft.) headway can 

provide this assurance. 

Based on the results of NHTSA’s 

recent model year 2021–2022 research 

testing, and in an effort to harmonize 

test procedures as much as possible 

with other consumer information 

programs per the BIL mandate, NHTSA 

will conduct tests using both 12 m (39.4 

ft.) and 40 m (131.2 ft.) headways for 

both test speeds selected for CIB LVD 

testing. 

CIB POV Deceleration Magnitude for the 

LVD Test Scenario 

With respect to NHTSA’s proposal to 

increase the POV deceleration 

magnitude currently specified in 

NCAP’s CIB LVD test procedure from 

0.3g to 0.5g or 0.6g for this upgrade of 

NCAP, the Agency has decided to retain 

a 0.3g POV deceleration in its CIB LVD 

tests and adopt a 0.5g POV deceleration 

specification.110

While NHTSA sought comments on 

adopting a 0.6g POV deceleration for 

LVD testing and received some 

supportive feedback regarding this idea 

due in part to Euro NCAP’s use of a 

similar test specification (6 m/s2), the 

Agency reasons that adopting a 

maximum 0.6g POV deceleration is not 

appropriate at this time. Although 

harmonization is generally desired, Euro 

NCAP requires only a 50 kph (31.1 mph) 

test speed for its CCRb test and provides 

partial credit for speed reduction, while 

NHTSA has also adopted an 80 kph 

(49.7 mph) test speed and is moving 

forward with a no contact passing 

criterion for its CIB testing (as discussed 

later). Additionally, as mentioned in its 

March 2022 RFC notice, NHTSA 

observed excessive wear on the GVT’s 

tires (i.e., flat-stopping due to wheel 

lockup) while conducting research 

testing during braking maneuvers where 

the POV deceleration was near 0.6g, and 

found it was more difficult to achieve 

and accurately control deceleration 

within the prescribed tolerances when 

braking maneuvers were performed with 

decelerations higher than 0.5g, even 

with extensive tuning efforts. 

Commenters also suggested that a 0.5g 

deceleration was less likely than a 0.6g 

deceleration to introduce repeatability 

issues or cause damage to test 

equipment. To limit potential testing 

challenges, NHTSA is adopting a 0.5g 

maximum POV deceleration for NCAP’s 

updated LVD test requirements at this 

time but may consider incorporating a 

0.6g deceleration as part of future 

program updates if testing concerns can 

be alleviated. 

The Agency notes that many 

commenters asserted a 0.5g deceleration 

was representative of real-world driving. 

NHTSA’s previous research suggests 

that drivers decelerate up to 

approximately 0.3g in a non-emergency 

situation and up to approximately 0.5g 

when encountering an unexpected 

obstacle.111 Additionally, past NHTSA 

research analysis of rear-end crash event 

data recorder data showed that drivers 

applied the brakes at approximately 0.4g 


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112Automatic Emergency Braking System (AEB) 

Research Report, NHTSA, August 2014, pg. 47. 

https://www.regulations.gov/document/NHTSA2012-0057-0037. 

113 If a vehicle did not achieve full avoidance 

during the 0.4g POV deceleration test condition, the 

0.5g POV deceleration test condition was not 

assessed. 

114Swanson, E., Foderaro, F., Yanagisawa, M., 

Najm, W.G., & Azeredo, P. (2019, August), Statistics 

of light-vehicle pre-crash scenarios based on 2011– 

2015 national crash data (Report No. DOT HS 812 

745), Washington, DC: National Highway Traffic 

Safety Administration. 115Posted speed limit was unknown or not 

reported in 2 percent of fatal rear-end crashes and 

11 percent of rear-end crashes with injuries. 116Swanson, E., Foderaro, F., Yanagisawa, M., 

Najm, W.G., & Azeredo, P. (2019, August), Statistics 

in rear-end crash scenarios.112

Therefore, a POV deceleration of 0.5g 

seems reasonable to adopt (i.e., 

compared to 0.6g) when real-world 

driving data are considered. 

Given these data, there is also reason 

to retain the 0.3g POV deceleration 

currently specified in the Agency’s CIB 

test procedure. Adopting this lower 

deceleration magnitude in addition to 

0.5g will ensure vehicles continue to 

perform as expected in situations where 

the lead vehicle decelerates at a more 

moderate rate. The Agency reasons that 

CIB systems should function whether 

the lead vehicle is engaged in an 

emergency maneuver or not. AEB 

systems that perform well in a test with 

higher lead vehicle deceleration may 

not necessarily offer comparable or 

better performance in tests with lower 

lead vehicle decelerations. The Agency 

also notes Euro NCAP takes a similar 

approach to testing in its CCRb scenario. 

In addition to the previously mentioned 

6 m/s2 (19.7 ft./s2) deceleration, Euro 

NCAP prescribes a lower POV 

deceleration of 2 m/s2 (6.6 ft./s2). Tesla 

and Advocates also agreed with such a 

testing approach. By adopting two POV 

deceleration rates for NHTSA’s NCAP 

testing, manufacturers will need to 

demonstrate that their vehicles offer 

consistent performance by effectively 

recognizing and responding to lead 

vehicles that are braking at various 

rates. 

While much of the Agency’s recent 

model year 2021–2022 research testing 

was conducted using a 0.4g POV 

deceleration in addition to a 0.5g POV 

deceleration at each headway and test 

speed, NHTSA is not adopting a POV 

deceleration of 0.4g for its future NCAP 

testing. At the lower test speed of 50 

kph (31.1 mph) and longer headway of 

40 m (39.4 ft.), all vehicles achieved full 

avoidance when the POV decelerated at 

0.4g and all but one vehicle met the nocontact requirements at a POV 

deceleration of 0.5g. Reducing the 

headway to 12 m (39.4 ft.) made this test 

condition more challenging, with half 

the vehicles tested achieving full 

avoidance when subjected to POV 

decelerations of 0.4g and 0.5g.113 As 

noted earlier in this notice, higher-speed 

LVD testing (i.e., 80 kph (49.7 mph)) 

was more rigorous, and few vehicles 

offered full avoidance for either 

headway. However, for the 80 kph (49.7 

mph) conditions, vehicles that achieved 

full avoidance in a given 0.4g POV 

deceleration test condition also 

achieved full avoidance when subjected 

to the same condition but with a POV 

deceleration of 0.5g. While the Agency 

has noted (above) that vehicles may not 

always provide comparable or better 

performance for lower POV 

decelerations, NHTSA’s test data shows 

they often do, thus suggesting it may be 

appropriate for NCAP, in consideration 

of limiting test burden, to adopt one of 

these decelerations (i.e., 0.4 or 0.5g) 

without sacrificing the program’s efforts 

to ensure robust CIB system 

performance. This decision seems 

especially reasonable since NHTSA has 

decided to retain a 0.3g POV 

deceleration while adding a 0.5g 

deceleration. 

For the LVD CIB scenario, NHTSA 

will impose a similar testing assessment 

process to that adopted for the LVS and 

LVM CIB scenarios. The Agency will 

perform the LVD CIB test conditions in 

a manner consistent with increasing 

stringency. The first LVD trial will be 

performed at the minimum test speed 

(50 kph (31.1 mph)), maximum 

headway (40 m (131.2 ft.)), and 

minimum deceleration (0.3g). If the 

initial trial run is valid (i.e., all test 

specifications and tolerances are 

satisfied) and the SV does not contact 

the POV, the Agency will proceed with 

conducting the next trial run at the same 

test speed (50 kph (31.1 mph)) and 

deceleration (0.3g) but will adjust the 

headway to the minimum specified 

distance, 12 m (39.4 ft.). If the vehicle 

does not contact the POV for this test 

condition and the trial run is 

determined to be valid, NHTSA will 

then increment the test speed to the 

maximum LVD test speed, 80 kph (49.7 

mph), and perform one trial run at the 

maximum headway (40 m (131.2 ft.)) 

and minimum deceleration (0.3g), 

followed by one trial run at 80 kph (49.7 

mph), minimum headway (12 m (39.4 

ft.)), and minimum deceleration (0.3g). 

If no vehicle-to-POV contact is observed 

and all 80 kph (49.7 mph) trials are 

considered valid, the Agency will repeat 

the LVD test sequence utilizing a POV 

deceleration of 0.5g. See Table 14 for the 

sequence of CIB LVD tests. 

DBS Testing in NCAP 

After consideration of the most recent 

research data and comments received 

from the public in response to the 

March 2022 RFC notice, the Agency has 

decided to retain DBS testing in NCAP. 

For the LVS and LVM scenarios, 

NHTSA will perform DBS assessments 

at the two highest test speeds adopted 

for the complementary CIB test 

scenarios—70 kph (43.5 mph) and 80 

kph (49.7 mph)—as well as two 

additional speeds, 90 kph (55.9 mph) 

and 100 kph (62.1 mph). The 

performance criterion for each 

assessment will be ‘‘no contact,’’ and 

the POV speeds adopted for DBS will 

align with those adopted for CIB 

evaluation (i.e., 0 kph (0 mph) for the 

LVS scenario and 20 kph (12.4 mph) for 

the LVM scenario). For the LVD 

scenario, the Agency will perform DBS 

assessments in all eight test conditions 

covered by CIB: 50 kph (31.1 mph) and 

80 kph (49.7 mph), each at 12 m (39.4 

ft.) and 40 m (131.2 ft.) headways and 

each with 0.3g and 0.5g POV 

deceleration. Like the LVS and LVM 

DBS tests, the performance criterion 

adopted for the LVD DBS assessment 

will be ‘‘no contact.’’ 

NHTSA notes that commenter 

suggestions on appropriate DBS test 

speeds varied. Some suggested that the 

Agency conduct CIB and DBS tests at 

the same speeds or alternate between 

CIB and DBS testing above certain 

speeds. Others recommended that 

NHTSA perform CIB tests at lower 

speeds and DBS tests at higher speeds, 

albeit sometimes with slight deviations 

(e.g., conducting DBS testing at the next 

highest speed once the CIB system fails 

to provide complete avoidance.) Several 

commenters also stated that NHTSA 

should conduct AEB assessments, in 

general, at speeds higher than those 

proposed, citing the need to better 

reflect real-world driving conditions 

and foster ideal system performance. 

There is merit to these commenters’ 

recommendations for NCAP’s DBS tests. 

In its real-world data analysis, Volpe 

found that, for rear-end crashes where 

posted speed was known, over 37 

percent of fatalities and 21 percent of 

injuries occurred on roadways having 

posted speeds between 80 kph (49.7 

mph) and 100 kph (62.1 mph).114 115

By adopting two additional higher test 

speeds for NCAP’s LVS and LVM test 

scenarios (i.e., 90 kph (55.9 mph) and 

100 kph (62.1 mph)) in addition to those 

proposed (i.e., 70 kph (43.5 mph) and 80 

kph (49.7 mph)), the program’s DBS 

tests would represent the posted speeds 

at which more than 65 percent of 

fatalities and 91 percent of injuries 

occurring in rear-end crashes.116


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Federal Register / Vol. 89, No. 232 / Tuesday, December 3, 2024 / Notices 95945 

of light-vehicle pre-crash scenarios based on 2011– 

2015 national crash data (Report No. DOT HS 812 

745), Washington, DC: National Highway Traffic 

Safety Administration. 

117This same vehicle, when tested for the LVD 

scenario with the more stringent headway and POV 

deceleration (i.e., a 12 m headway and 0.5g POV 

deceleration), was also able to avoid collision when 

tested at 50 kph (31.1 mph) and 80 kph (49.7 mph). 

118The time between FCW onset and braking 

initiation for this testing was set at 1.0 second, 

which is the timing being adopted in this final 

notice (see later section). 

119https://www.regulations.gov/document/ 

NHTSA-2023-0021-0005. 

NHTSA’s testing has shown such test 

speeds to be practicable with respect to 

both testing feasibility and current AEB 

system capabilities. In its model year 

2021–2022 research testing, one vehicle 

was able to provide complete crash 

avoidance up to 100 kph (62.1 mph) for 

all LVM and LVS test conditions.117

This is likely because a speed 

differential of 80 kph (49.7 mph) in the 

Agency’s LVS CIB test, where no 

manual braking is imparted, affords 

similar stringency to the Agency’s LVS 

DBS test scenario for a test speed of 100 

kph (62.1 mph), where manual braking 

at a constant average deceleration of 

0.4g is required. The Agency also 

maintains that a 100 kph (62.1 mph) 

LVS DBS test would require braking that 

is no harsher than that currently 

demonstrated by vehicles compliant 

with FMVSS No. 135, ‘‘Light vehicle 

brake systems.’’ In addition, a maximum 

subject vehicle test speed of 100 kph 

(62.1 mph) in the Agency’s DBS LVM 

test affords similar stringency as a test 

speed of 80 kph (49.7 mph) in its DBS 

LVS test since the POV speed in the 

LVM test is 20 kph (12.4 mph), and 

thus, the relative speed between the 

subject vehicle and POV is 80 kph (49.7 

mph). 

While NHTSA is adopting a 100 kph 

(62.1 mph) maximum speed for its DBS 

LVS and LVM assessments, NHTSA’s 

proposed maximum speed of 80 kph is 

appropriate for its DBS LVD assessment. 

As mentioned for the CIB LVD test, 

there was some concern regarding the 

ability to perform LVD testing reliably at 

80 kph (49.7 mph). While research data 

has shown that testing at this speed is 

feasible and practicable, LVD research 

testing has not been conducted at 

speeds higher than 80 kph (49.7 mph). 

As such, the Agency hesitates to raise 

the DBS LVD test speeds to match those 

for LVS and LVM. Another concern 

raised in response to the March 2022 

RFC was related to the LVD scenario 

and FCW timing for higher test speeds, 

with Toyota and Intel both noting there 

may not be sufficient time to: (1) issue 

the FCW, (2) wait for the prescribed 

amount of time between FCW and brake 

activation (i.e., 1.0 second, as proposed), 

and (3) initiate braking during an LVD 

assessment where POV deceleration is 

0.5g and headway is 12 m (39.4 ft.). In 

fact, Toyota stipulated that the POV may 

not have even begun decelerating at the 

time at which the FCW would need to 

be issued. However, during its research 

testing, NHTSA found many vehicle 

models are currently available to meet 

this criterion.118 In the 12 m (39.4 ft.) 

headway LVD tests with 0.5g POV 

deceleration, for a 50 kph (31.1 mph) 

test speed, eight vehicle models were 

able to fully avoid the POV. For the 80 

kph (49.7 mph) test speed, four were 

able to achieve full avoidance.119 These 

results confirm that the requirements 

adopted for the LVD test conditions are 

feasible for current DBS systems. The 

Agency’s decision (discussed later) to 

explicitly allow automatic braking 

resulting from CIB activation after 

issuance of the FCW but prior to manual 

brake application during DBS testing is 

also an important consideration, as it 

ensures the SV is provided with the best 

overall opportunity to avoid the POV 

regardless of whether a manual brake 

application is being used. 

Although there was overall support 

for retaining DBS testing in NCAP, 

NHTSA also recognizes that a few 

commenters suggested that continued 

testing for this technology was 

unnecessary. For example, Subaru 

stated that NHTSA remove DBS 

assessments from NCAP because DBS 

systems have a record of good 

performance. The automaker reasoned 

that mature ADAS technologies with 

high adoption rates could be removed 

and replaced with other emerging 

technologies. In general, NHTSA agrees 

with this approach, but it does not agree 

there are no further gains to be made 

regarding DBS performance. Model year 

2021–2022 research testing showed that, 

at test speeds greater than 80 kph (49.7 

mph), vehicle models offered a range of 

DBS performance in the LVM test. Of 

the 12 models, four did not offer full 

avoidance at 90 kph (55.9 mph) and an 

additional five did not offer full 

avoidance at 100 kph (62.1 mph). For 

the DBS LVS condition, five did not 

offer full avoidance at 70 kph (43.5 

mph), three did not offer full avoidance 

at 80 kph (49.7 mph), two did not offer 

full avoidance at 90 kph (55.9 mph), and 

another one did not offer full avoidance 

at 100 kph (62.1 mph). Further, one 

vehicle was able to fully avoid contact 

through 80 kph (49.7 mph) in the CIB 

LVS tests but did not avoid contact in 

the 90 kph (55.9 mph) DBS LVS test, 

which would be expected to be less 

challenging based on the additional 

manual braking imparted by the driver. 

DBS LVD assessments at 80 kph (49.7 

mph) also demonstrated room for 

improvement in the same study. When 

the POV deceleration was 0.4g, only five 

of the total 12 vehicles tested were able 

to fully avoid the POV for the 40 m 

(131.2 ft.) headway test condition, while 

six of the total 12 were able to fully 

avoid the POV in the 12 m (39.4 ft.) 

headway test condition. When the POV 

deceleration was increased to 0.5g, only 

three of five vehicle models tested for 

the 80 kph (49.7 mph), 40 m (131.2 ft.) 

headway test condition provided full 

avoidance and four of the six vehicle 

models achieved this performance for 

the 12 m (39.4 ft.) headway test 

condition. Several commenters also 

stated that continuing to perform DBS 

testing for each of the test conditions 

adopted for CIB would be redundant 

and only serve to increase test burden. 

The Agency’s decision to adopt 

additional higher test speeds than those 

adopted for CIB (i.e., 90 kph (55.9 mph) 

and 100 kph (62.1 mph)) for its LVS and 

LVM tests, in addition to a ‘‘no contact’’ 

performance criterion, effectively 

ensures that the majority of NCAP’s DBS 

tests will be as stringent as the 

program’s CIB tests. Thus, it is not 

necessary at this time to require a higher 

level of stringency in NCAP’s DBS tests 

compared to its CIB tests to justify the 

need to retain DBS testing in NCAP. 

Rather, the Agency agrees with those 

commenters who suggested that DBS 

testing in NCAP is necessary to ensure 

that brake pedal application does not 

adversely affect overall AEB 

functionality or suppress CIB operation. 

If a driver attempts to brake but does so 

with an input that is insufficient to 

avoid a crash, the vehicle’s DBS system 

must support the driver’s action and 

intention to stop the vehicle. 

With respect to the assessment 

approach to be used for NCAP’s DBS 

tests, the Agency plans to align its 

approach for the LVS and LVM DBS 

tests with those finalized for CIB; 

however, the first and last SV speed in 

the respective test series will be higher. 

NHTSA will initiate the DBS test 

sequence for each of the LVS and LVM 

scenarios by performing a trial run at 

the minimum DBS test speed in the 

sequence (i.e., 70 kph (43.5 mph)) and 

will then incrementally increase the test 

speed by 10 kph (6.2 mph) to assess the 

next test condition in the sequence (i.e., 

80 kph (49.7 mph)), as long as the initial 

trial run is valid (i.e., all test 

specifications and tolerances satisfied) 

and the SV does not contact the POV. 

This incremental process will continue 


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120This is not to suggest that camera systems are 

superior to radar systems in all tests. 

121RGB cameras are cameras that can capture 

light in red, green, and blue (hence, RGB) 

wavelengths. 

until the maximum test speed of 100 

kph (62.1 mph) is assessed. 

For the LVD scenario, NHTSA will 

impose a DBS testing assessment 

process that is identical to that adopted 

for the LVD CIB tests. The Agency will 

conduct the first LVD trial at the 

minimum test speed (50 kph (31.1 

mph)), maximum headway (40 m (131.2 

ft.)), and minimum deceleration (0.3g). 

If the initial trial run is valid (i.e., all 

test specifications and tolerances 

satisfied) and the SV does not contact 

the POV, the next trial run will be 

conducted at the same test speed (50 

kph (31.1 mph)) and deceleration (0.3g) 

but the headway will be adjusted to the 

minimum specified distance, 12 m (39.4 

ft.). If the vehicle fully avoids contacting 

the POV for this test condition and the 

trial run is determined to be valid, 

NHTSA will then increment the test 

speed to the maximum LVD test speed, 

80 kph (49.7 mph), and will perform 

one trial run at the maximum headway 

(40 m (131.2 ft.)) and minimum 

deceleration (0.3g), followed by one trial 

run at 80 kph (49.7 mph), minimum 

headway (12 m (39.4 ft.)), and minimum 

deceleration (0.3g). If no vehicle-to-POV 

contact is observed and all 80 kph (49.7 

mph) trials are considered valid, the 

Agency will repeat the LVD DBS test 

sequence utilizing a POV deceleration of 

0.5g. See Table 15 for the sequence of 

LVD DBS tests. 

The test conditions, performance 

criteria, and assessment approaches 

adopted for the LVS, LVM, and LVD 

DBS test scenarios will allow NHTSA to 

keep test burden to a minimum while 

confirming functionality of DBS systems 

and ensuring acceptable system 

performance across a range of real-world 

driving conditions, as Advocates 

requested. 

c. Removal of False Positive 

Assessments 

When the STP test was initially 

developed, many AEB systems relied 

solely on radar for lead vehicle 

detection. Today, most vehicles utilize a 

camera-only or fused system that relies 

on both camera and radar. While some 

radar-only systems have had difficulty 

classifying the STP correctly (i.e., 

responding to the STP as if it was a 

vehicle), camera-only and fused systems 

have not exhibited this issue.120 Since 

its AEB testing began in NCAP for 

model year 2017 vehicles, the Agency 

has observed no instances of false 

positive test failures during CIB and 

DBS NCAP evaluations performed for 

camera-only and fused AEB systems. 

Since fused camera-radar forwardlooking AEB systems are becoming more 

prevalent in the fleet, NHTSA suggested 

it might be appropriate to remove the 

false positive STP assessments from 

NCAP’s AEB (i.e., CIB and DBS) 

evaluation matrix as part of this NCAP 

update and sought comment in that 

regard. 

Summary of Comments 

Approximately two-thirds of 

commenters stated that NHTSA could 

remove the STP false positive 

assessment from NCAP’s AEB test 

matrix. The remaining one-third urged 

the Agency to continue to conduct false 

positive tests. 

Remove False Positive Tests 

The following commenters supported 

removal of the STP false positive tests 

from NCAP’s AEB test matrix: Auto 

Innovators, BMW, Bosch, GM, HATCI, 

Honda, IDIADA, IIHS, Intel, MEMA, 

Rivian, Toyota, and TRC. 

Toyota and HATCI cited improved 

performance of the latest technologies, 

as demonstrated by NCAP test results, 

as a reason to remove the STP tests. 

Likewise, TRC mentioned that vehicles 

may occasionally issue an alert when 

driven over the steel trench plate during 

testing, but they no longer activate AEB. 

Bosch supported removal of the STP 

assessments from both CIB and DBS test 

procedures due to concerns about the 

tests’ repeatability and representation of 

all real-world driving situations. Along 

the same lines, GM mentioned that the 

Agency’s current STP false positive tests 

address only a very limited number of 

potential conditions that vehicle 

manufacturers and suppliers must 

assess as part of their due diligence to 

ensure sensors and systems respond 

appropriately (i.e., without issuing false 

activations) when driven in a myriad of 

driving environments and conditions. 

Auto Innovators and BMW agreed that 

NCAP’s false positive tests are 

inadequate to address all potential 

conditions that may incite a false 

positive event for all AEB systems. As 

such, the commenters asserted that they 

only serve to unnecessarily increase test 

burden without providing appreciable 

safety benefit. 

Both GM and Auto Innovators 

suggested that, in lieu of conducting 

false activation tests, NHTSA should 

monitor customer complaints about 

frequent false activation events. Both 

commenters stated that this information 

would be more useful to NHTSA. IIHS 

also favored such an approach to 

addressing false-positive braking 

problems. IIHS remarked that NHTSA 

has received customer complaints and 

opened investigations for false positive 

activations for both radar-only and 

camera-based AEB systems despite 

currently performing false positive tests 

and only witnessing failures for radaronly systems. Accordingly, the 

commenter concluded that not only are 

the current tests insufficient to address 

all instances of real-world false 

activations, but also the Agency could 

use its authority through a recall process 

to address false positive braking 

problems as they arise. IIHS further 

mentioned that vehicle manufacturers 

are sufficiently motivated to minimize 

false-positive interventions by customer 

feedback such that false positive AEB 

tests are not necessary. 

Honda and HATCI also stated that the 

current false positive tests no longer 

address a safety need, particularly since, 

as Honda added, cameras are now a 

fundamental component of AEB, and 

their performance should continue to 

improve. Rivian agreed that most 

vehicles rely on fused data (i.e., 

involving cameras) for FCW and CIB 

activations but also cautioned that 

‘‘some manufacturers still rely on radar 

confidence and allow low deceleration 

radar-only braking.’’ As such, the 

manufacturer recommended that the 

Agency should incorporate scenarios 

that could trigger radar-only braking if 

it wants to evaluate a vehicle’s 

propensity to issue false positive 

braking. Similarly, FCA commented that 

it would be appropriate for the Agency 

to remove the STP assessment for 

vehicles equipped with camera-based 

systems, but NHTSA should continue 

those assessments for vehicles using 

radar-only systems. Intel stated that 

false positive STP evaluations were now 

‘‘redundant’’ for CIB and DBS because 

the Agency has relaxed the allowable 

deceleration threshold. 

Continue To Perform False Positive 

Tests 

Some commenters (including Adasky, 

Advocates, CAS, Tesla, Vayyar, and ZF 

Group) stated that NHTSA should 

continue to conduct false positive 

assessments as part of NCAP’s AEB test 

evaluations. 

Adasky stated that NHTSA should 

retain the false positive AEB tests in 

NCAP because ‘‘they serve as an 

indication of the lack of robustness of 

RGB cameras and radars.’’ 121 The 

supplier also suggested that thermal 

cameras should be encouraged (or 

required) because they may address 

‘‘phantom braking’’ in real-world cases. 


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Adasky noted that thermal cameras offer 

more robust detection and provide the 

redundancy necessary to overcome RGB 

camera and radar deficiencies. Vayyar 

explained that removal of false positive 

assessments from NCAP would serve to 

foster development of ‘‘suboptimal 

technologies’’ and drive an increase in 

real-world false positive events. ZF 

Group reasoned that current and future 

AEB systems would not necessarily be 

prone to false positive activations, but 

in the interest of safety, the group 

recommended retaining STP false 

positive tests in NCAP to ensure 

systems continue to work as expected. 

Tesla commented that false positive 

activations may become more common 

as vehicle sensing technologies continue 

to evolve. Accordingly, the automaker 

recommended that NHTSA continue to 

conduct the current false positive STP 

assessments since they may help 

provide nuanced distinctions in AEB 

performance among vehicles relying on 

different sensing technologies in the 

future. Tesla stated this would permit a 

more comprehensive rating. 

CAS also stated that NHTSA should 

continue performing false positive STP 

assessments for AEB. The commenter 

noted that it would be inappropriate to 

assume system capabilities without test 

verification, especially since false 

positive activations have been reported 

for production vehicles, and there are 

many reasons for system failures, 

including supply chain disruptions, 

design or production issues, and 

manufacturing defects. Advocates 

opposed eliminating the false positive 

AEB assessments from NCAP until they 

were adopted into regulations. 

Response to Comments and Agency 

Decisions 

The Agency will retain the STP false 

positive test in NCAP’s AEB evaluation 

matrix. The test scenario will be 

conducted as part of both CIB and DBS 

system assessments as is done currently 

in NCAP. However, instead of 

performing the STP test at the currently 

prescribed test speeds, 40.2 and 72.4 

kph (25 and 45 mph), the Agency is 

adopting only a test speed of 80 kph 

(49.7 mph) to mirror the highest test 

speed adopted for CIB testing. 

NHTSA reasons it is no longer 

necessary to conduct AEB STP tests at 

40.2 kph (25 mph) because the Agency 

has observed no instances of false 

positive test failures during CIB and 

DBS NCAP evaluations performed since 

the tests were added to the program for 

model year 2017 vehicles. Requiring 

only one test speed instead of two for 

NCAP’s CIB and DBS STP assessments 

should also help to offset any added test 

burden imposed by the 90 and 100 kph 

(55.9 and 62.1 mph) assessments 

adopted for the program’s LVM and LVS 

DBS test scenarios. The slight increase 

in test speed (from 72.4 kph (45 mph), 

as currently prescribed for NCAP’s STP 

tests, to 80 kph (49.7 mph), as adopted) 

for the higher speed test condition is 

reasonable and justifiable to 

complement the performance 

requirements adopted for the Agency’s 

other AEB tests. During NHTSA’s AEB 

research testing for model year 2021– 

2022 vehicles, no AEB false positives 

(i.e., unnecessary system activations) 

were observed for any of the twelve 

vehicles evaluated during the conduct 

of valid CIB and DBS trials for the STP 

scenario at a test speed of 80 kph (49.7 

mph). 

Although some commenters 

supported removal of the false positive 

tests, others encouraged the Agency to 

continue to conduct such tests in NCAP. 

Adasky, Tesla, and Vayyar expressed 

concerns surrounding a lack of sensor 

robustness and an increase in false 

activations with system evolution if 

NHTSA was to stop performing false 

positive tests in NCAP. While the 

Agency has not observed false positive 

test failures in CIB or DBS testing since 

NHTSA added these ADAS technologies 

to NCAP, and similarly did not observe 

failures in NHTSA’s research tests for 

model year 2021–2022 vehicles, it 

agrees with these commenters that it 

should exercise due diligence given the 

anticipated system changes that will be 

necessary to ensure current system 

functionality is maintained as sensing 

technologies evolve and as CIB test 

speeds increase. The Agency remains 

concerned that false activation events 

may introduce hard braking situations 

when such actions are not warranted, 

potentially causing rear-end crashes 

instead of mitigating them. Since the 

consequences of unintended braking 

can be more significant at higher vehicle 

travel speeds, retaining the highest 

proposed test speed (i.e., 80 kph (49.7 

mph) is most appropriate. It is not 

appropriate at this time to adopt a test 

speed higher than 80 kph (49.7 mph) for 

the program’s CIB and DBS STP test 

assessments, such as the maximum test 

speed adopted for NCAP’s DBS tests 

(i.e., 100 kph (62.1 mph)), since, to date, 

NHTSA has not performed research 

testing at speeds higher than 80 kph 

(49.7 mph) for the STP test. 

Of those commenters that suggested 

the Agency should remove the false 

positive test conditions from NCAP’s 

AEB test matrix, some, like Honda and 

HATCI, stated the current STP test no 

longer addresses a safety need. 

However, NHTSA contends that if 

NCAP’s STP test provides even limited 

coverage of real-world false positive 

conditions, it is still beneficial. Along 

these lines, continuing false positive 

testing in NCAP should lessen Auto 

Innovators’ concern that an increase in 

false positives during real-world driving 

may discourage AEB use. 

Some commenters asserted that 

performing false positive tests in NCAP 

should be unnecessary since vehicle 

manufacturers have an incentive to 

maintain high customer satisfaction; 

therefore, they will design AEB systems 

to thoroughly address the potential for 

unwarranted braking in real-world 

driving scenarios. GM asserted that it is 

the vehicle manufacturers’ 

responsibility to ensure systems 

respond appropriately. NHTSA agrees 

with these commenters in theory and 

expects vehicle manufacturers to design 

AEB systems to thoroughly address the 

potential for false activations in a 

myriad of possible real-world situations 

so that vehicles do not pose an 

unreasonable risk to safety. However, 

the Agency also recognizes that it has 

received customer complaints and 

opened investigations for false positive 

activations for AEB systems. This 

suggests that the motivation of positive 

consumer feedback and accountability 

alone may be insufficient to fully 

eliminate false positive activations. 

Therefore, it is appropriate to retain 

false positive testing in NCAP’s AEB test 

matrix. The Agency maintains this 

position while acknowledging that 

current false positive tests are neither 

comprehensive nor sufficient to 

eliminate susceptibility to all false 

activations. The false activation tests 

serve to provide a baseline for system 

functionality and to establish a 

minimum expected performance level. 

To address real-world conditions not 

covered by NCAP’s false positive test, 

NHTSA will continue to monitor 

customer complaints to look for reports 

of frequent false activations as part of its 

oversight. The Agency will conduct 

investigations, as necessary, to 

determine whether vehicles 

experiencing excessive false positive 

activations have a safety-related defect 

and thus pose an unreasonable risk to 

safety. The Agency will continue to 

handle such cases appropriately as they 

arise. NHTSA also plans to amend or 

supplement the STP test with other false 

positive activation tests or criteria as 

needed based on real-world data. 

Peak Additional Deceleration in DBS 

False Positive Test 

Currently, in NCAP’s STP DBS test, a 

vehicle’s DBS system must not engage 

the brakes to create a peak deceleration 


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122 80 FR 68608 (Nov. 5, 2015). 

123A performance criterion of ‘‘no contact’’ is 

currently specified for the lower speed LVM 

scenario (i.e., SV speed of 40.2 kph (25 mph) and 

POV speed of 16.1 kph (10 mph)). 

124NHTSA Traffic Safety Facts: Speeding 2019 

Data, DOT HS 813 194 (Published October 2021). 125European New Car Assessment Programme 

(Euro NCAP) (November 2022), Assessment 

Protocol—Safety Assist—Collision Avoidance, 

Version 10.2. 

that is greater than 1.5 times the average 

of the peak decelerations imparted by 

manual brake application during 

‘‘baseline’’ tests, which are conducted to 

simulate the magnitude of brake 

application needed to produce 0.4g 

deceleration using the vehicle’s 

foundation brakes. For the Agency’s 

future DBS STP tests, the DBS system 

must not engage the brakes to create a 

peak deceleration of more than 0.25g 

additional deceleration beyond the 

average of the peak decelerations 

recorded during the DBS STP 

‘‘baseline’’ runs. NHTSA is making this 

change because the lower braking 

threshold, which equates to a maximum 

combined braking level of 0.65g (i.e., 

combining the 0.4g from the 

foundation’s brakes with a possible 

0.25g additional deceleration), is more 

appropriate for the false positive test, 

which offers no real crash threat. 

The Agency will also make a similar 

change for its CIB false positive test. 

Instead of stipulating that a vehicle 

cannot impart braking that exceeds 0.5g 

in NCAP’s CIB STP test, NHTSA is 

amending the criterion to reflect a 

maximum peak braking of 0.25g. 

Effectively, the vehicle’s CIB system 

must not engage the brakes to create a 

peak deceleration of more than 0.25g 

during the CIB STP test. 

In imposing these modified 

requirements, a mild DBS intervention, 

such as that stemming from a haptic 

brake pulse, is deemed acceptable, but 

one where the vehicle thinks it must 

respond to the STP as if it was a real 

vehicle is not. 

Brake Pedal Application Rate in DBS 

False Positive Test 

Since the Agency has decided to 

retain the false positive test scenarios 

for its AEB tests, it plans to retain the 

current brake pedal application rate of 

254 ± 25.4 mm/s (10 ± 1 in./s) for the 

DBS test, as discussed in the March 

2022 RFC notice. 

In response to NHTSA’s December 

2015 RFC notice, BMW had suggested 

that the Agency should allow 

manufacturers to specify a brake pedal 

application rate limit up to 400 mm/s 

(16 in./s) for the false positive DBS test 

scenario to harmonize with Euro NCAP 

requirements. BMW asserted that 

limiting the rate to a lower threshold 

could increase a DBS system’s 

sensitivity and thereby increase the 

likelihood of additional false activation 

events in the real world. 

As the Agency mentioned in its RFC 

notice, the current application rate 

value is not only well within the brake 

application rate range of 200 to 400 mm/ 

s (8 to 16 in./s) specified by Euro 

NCAP,122 but also has been shown to 

provide the input characteristics needed 

to satisfy DBS activation thresholds 

during NHTSA NCAP testing. To reduce 

the potential for an unintended 

intervention, activation of conventional 

brake assist systems typically requires 

higher brake pedal application rates 

than those required for DBS. This is 

because conventional brake assist 

systems assume that if the driver applies 

the brakes quickly (i.e., with a brake 

pedal velocity profile used by drivers in 

an emergency/panic situation), 

supplemental braking is appropriate, 

whereas DBS systems consider data 

from forward-looking sensors and how 

the driver is applying the brakes. The 

additional data used by DBS allows the 

brake pedal velocity threshold to be 

lower than that of conventional brake 

assist systems. Thus, retaining the brake 

application rate of 254 ± 25.4 mm/s (10 

± 1 in./s) in the DBS system 

performance test enables NHTSA to 

focus on evaluating DBS system 

performance instead of conventional 

brake technology. 

d. No Contact Versus Speed Reduction 

Performance Criterion 

In its March 2022 RFC notice, NHTSA 

proposed to adopt a performance 

criterion of ‘‘no contact’’ for both CIB 

and DBS tests. Although NHTSA’s DBS 

test procedure currently specifies ‘‘no 

contact’’ as the performance criterion for 

all DBS test conditions, the Agency’s 

CIB test procedure specifies speed 

reduction as the passing requirement for 

all but one CIB test condition.123 Under 

the Agency’s proposal, the SV would 

have to avoid contacting the POV test 

device to pass CIB and DBS test trials. 

NHTSA reasoned that this approach 

would limit damage to the SV and POV 

test device during testing, thus 

maintaining test repeatability and 

vehicle test device usability. However, 

as alternatives to this proposal, NHTSA 

also asked if it would be more 

appropriate to require minimum speed 

reductions or specify a maximum 

allowable SV-to-POV impact speed for 

any or all of the proposed AEB test 

conditions (i.e., test scenario and test 

speed combinations). 

Summary of Comments 

Speed Reduction is Appropriate 

Most respondents (Auto Innovators, 

BMW, DENSO, GM, HATCI, Honda, 

IIHS, Intel, Subaru, Tesla, and Toyota) 

favored a speed reduction performance 

criterion in lieu of ‘‘no contact’’ because 

of its implication for safety benefits. 

BMW, DENSO, IIHS, and Subaru stated 

that speed reduction was appropriate for 

all AEB test scenarios because it 

mitigates crash severity, thus reducing 

vehicle damage, the risk of injury, and 

injury severity. Similarly, GM voiced 

that, under many conditions (e.g., 

speeds above 40 kph (24.9 mph) for the 

tested scenarios), current systems do not 

have the capability to completely avoid 

a crash, and as such, speed reduction 

provides the ‘‘most relevant measurable 

safety benefit’’ for AEB systems because 

it directly correlates to injury risk. 

Therefore, the automaker suggested the 

Agency should assess speed reduction 

at test speeds ranging from 40 to 60 kph 

(24.9 to 37.3 mph). IIHS objected to a 

‘‘no contact’’ criterion whether the 

Agency proceeds with single trials, 

multiple trials, or single trials with 

follow-up trials. Like GM, Honda and 

Auto Innovators also asserted that many 

current AEB systems will not be able to 

achieve complete crash avoidance at 

higher speeds but will still provide a 

significant speed reduction. Honda and 

Auto Innovators, in addition to HATCI, 

stated that they were opposed to a ‘‘no 

contact’’ criterion because such an 

approach (i.e., pass/fail) does not 

accurately reflect the safety benefits 

inherent to speed reductions. Auto 

Innovators cited DOT HS 813 194 to 

highlight the influence speed reduction 

can have on crash severity.124

Auto Innovators and HATCI 

recommended NHTSA adopt a sliding 

scale with points awarded to systems 

that successfully avoid a crash and also 

those that provide speed reduction (at 

least for ‘‘the most challenging 

situations’’ (Auto Innovators)), with the 

former receiving full points and the 

latter receiving partial credit to better 

differentiate performance among the 

fleet.125 This approach is similar to that 

of Euro NCAP. Auto Innovators added 

points should be determined based on 

the corresponding injury risk gleaned 

from real-world data, and HATCI 

mentioned points should progressively 

decrease with decreasing speed 

reduction until the speed reduction 

does not provide statistically significant 

safety benefits. BMW mentioned that 

basing AEB performance assessments on 

speed reduction instead of pass/fail 

criteria would ‘‘more accurately’’ rate 

AEB systems and allow ratings to be 


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126See figure provided by Intel and Euro NCAP 

Assessment Protocol—Safety Assist Collision 

Avoidance v10.0 for Subaru. 

more easily adjusted in the future. 

Honda and Auto Innovators 

recommended the Agency adopt 

maximum allowable collision speed as 

a performance criterion for higher-speed 

test conditions (i.e., SV speeds of 70 and 

80 kph (43.5 and 49.7 mph) per Auto 

Innovators). Although HATCI favored a 

scoring approach based on speed 

reduction like that used by Euro NCAP, 

it noted that specifying a maximum 

allowable impact speed for all test 

conditions in lieu of ‘‘no contact’’ 

would also be acceptable. 

Adopting performance-based criteria 

(i.e., speed reduction) in lieu of pass/fail 

criteria (i.e., ‘‘no contact’’) was also 

preferred by Toyota for similar reasons 

to those already mentioned. 

Specifically, the manufacturer stated 

that performance-based criteria, such as 

speed reduction, can be associated with 

reducing injuries and fatalities to better 

represent real-world ADAS 

performance. The commenter also stated 

that adopting a speed reduction 

performance criterion could reduce the 

number of trials that are necessary (due 

to system variations) for vehicle 

assessments, which would ultimately 

reduce test burden. Therefore, like Auto 

Innovators, the automaker 

recommended assigning points for both 

crash mitigation and avoidance. 

Intel and Subaru suggested NHTSA 

adopt Euro NCAP’s speed reduction 

approach for the Agency’s CIB and DBS 

tests, with the latter commenter 

referencing Euro NCAP Assessment 

Protocol—Safety Assist Collision 

Avoidance v10.0.126 Intel suggested that 

it is important for NHTSA to distinguish 

between those systems that afford at 

least partial speed reduction and those 

that offer no speed reduction, especially 

at higher initial test speeds. 

Like Auto Innovators and HATCI, 

Rivian suggested that the Agency award 

points for speed reduction (at least for 

certain scenarios) in addition to having 

a ‘‘no contact’’ criterion to encourage 

manufacturers to continuously improve 

system performance for those scenarios. 

FCA, Bosch, and GM shared a similar 

sentiment. FCA suggested it may be 

appropriate to require ‘‘no contact’’ for 

LVS tests with speeds up to 30 kph 

(18.6 mph), but speed reduction should 

generally be required for higher test 

speeds since the ‘‘prediction time 

increases’’ for such conditions. The 

commenter stated a requirement of ‘‘no 

contact’’ may cause higher false positive 

rates, resulting in system deactivation in 

the real world. Bosch opined that ‘‘no 

contact’’ is an appropriate performance 

criterion for test speeds up to 60 kph 

(37.3 mph) but stated that points should 

be awarded for speed reductions as low 

as 10 kph (6.2 mph) for higher speed 

test conditions. 

No Contact Is Appropriate 

A few commenters asserted a 

performance criterion of ‘‘no contact’’ 

was appropriate for the Agency to adopt 

for its NCAP AEB testing. CAS 

expressed that ‘‘no contact’’ is the most 

appropriate performance criterion for 

the Agency’s AEB tests since the desired 

outcome of any CIB or DBS activation is 

to avoid contact. CAS also asserted that 

‘‘no contact’’ serves as a useful criterion 

for consumers when comparing 

vehicles, especially as speeds are 

increased. Finally, it stated that if the 

Agency found that a vehicle exhibited 

contact as test speeds were 

progressively incremented, then it 

should ‘‘regressively test at lower 

speeds’’ to determine ‘‘the maximum 

‘no contact’ speed,’’ which could then 

be used as the baseline to compare 

vehicles. 

Adasky commented that AEB systems 

should afford ‘‘no contact’’ even at 

higher test speeds and at night since 

thermal cameras are available and can 

help systems perform well under these 

conditions. Advocates stated that a ‘‘no 

contact’’ requirement is ‘‘essential,’’ but 

also suggested that the Agency consider 

assigning credit to systems that offer 

‘‘meaningful’’ speed reductions for 

tested speeds that fall outside of the 

range of performance afforded by 

current systems—both lower and higher. 

Response to Comments and Agency 

Decisions 

The Agency is proceeding with 

adopting a ‘‘no contact’’ criterion for 

NCAP’s AEB performance test 

requirements. Such a criterion is 

feasible to achieve, consistent with the 

safety need, and necessary to ensure test 

repeatability, among other reasons. 

Recent AEB testing has shown that 

several vehicles from the modern fleet 

were able to avoid contacting the 

vehicle test device for most of the test 

conditions adopted herein. For instance, 

one vehicle model provided complete 

avoidance in most of the adopted test 

conditions. This model did not provide 

full avoidance when tested using a 12 m 

(39.4 ft.) headway and 0.4g POV 

deceleration, so the more stringent 0.5g 

deceleration NCAP test condition using 

the same 12 m (39.4 ft.) headway was 

not performed. However, the vehicle’s 

relative impact speed for the 0.4g 

deceleration condition was relatively 

low, at 9.5 kph (5.9 mph) during the 

first trial. Consequently, it is reasonable 

to expect that minor changes could be 

made to the vehicle model’s AEB system 

such that it would be able to pass the 

CIB LVD, 12 m (39.4 ft.) headway and 

0.5g POV deceleration condition in the 

near future. Another vehicle model 

provided full avoidance in nearly every 

test condition, failing to completely 

avoid contact with the POV in only the 

CIB LVS test scenario. For this test 

scenario, the vehicle provided complete 

avoidance at test speeds through 60 kph 

(37.3 mph), and at 70 kph (43.5 mph), 

the vehicle provided partial speed 

reduction. Since full avoidance was not 

observed at 70 kph (43.5 mph), the 

vehicle was not subsequently tested at 

80 kph (49.7 mph). Thus, while several 

commenters mentioned that tested 

vehicles may currently have difficulty 

with completely avoiding contact with 

the vehicle test device, the 

aforementioned results suggest that the 

test requirements are practical for 

vehicles to achieve in the near future. 

Furthermore, manufacturers of these 

vehicles have shown that a ‘‘no contact’’ 

performance criterion can be met with 

no increase to false positive rates, even 

at higher test speeds, which was a 

concern expressed by FCA. To date, 

NHTSA has not received an increased 

number of false positive reports for 

either vehicle. 

In response to Rivian and FCA’s 

statements that adopting speed 

reduction as a performance criterion 

would encourage manufacturers to 

continuously improve system 

performance, particularly at higher test 

speeds, applying a ‘‘no contact’’ 

performance criterion should achieve 

the same goal. Vehicle manufacturers 

that wish to obtain NCAP credit for AEB 

must have vehicles that offer 

exceptional, robust system performance. 

Although it may be true that there are 

inherent safety benefits to adopting a 

maximum allowable impact speed or 

speed reduction performance criterion, 

as numerous commenters asserted, there 

are more profound safety benefits 

afforded by systems that offer complete 

crash avoidance. By promoting 

development of more robust AEB 

systems capable of much higher speed 

reductions and complete crash 

avoidance, AEB systems may effectively 

address a larger percentage of crashes 

that cause serious injuries and/or 

fatalities. 

It would be most advantageous to 

establish a ‘‘no contact’’ performance 

criterion for several other reasons. From 

a testing logistics perspective, the 

Agency has observed that it is possible 

for even relatively low-speed collisions 

with the lead vehicle test device to 


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127NHTSA’s proposal included several 

assessment alternatives for the LVD test scenario. 

These included testing one speed, 50 kph (31.1 

mph); two speeds, 50 kph (31.1 mph) and 80 kph 

(49.7 mph); or four speeds, 50, 60, 70, and 80 kph 

(31.1, 37.3, 43.5, and 49.7 mph). 

128The Agency notes that a similar pass/fail 

criterion (i.e., a vehicle must meet performance 

requirements for three out of five trials for a 

particular test condition to pass the test condition) 

is included in its current LDW test procedure, as 

referenced later in this document. 

129For the LVD test scenario, NHTSA proposed 

to adopt an SV and POV test speed of 50 kph (31.1 

mph) (i.e., one test condition) but also sought 

comment on whether it would be appropriate to 

incorporate additional SV and POV test speeds of 

60, 70, and 80 kph (37.3, 43.5, and 49.7 mph, 

respectively). Furthermore, for DBS specifically, the 

Agency sought comment on whether it was 

reasonable to only conduct LVS and LVM tests at 

only the highest two test speeds proposed for CIB— 

70 and 80 kph (43.5 and 49.7 mph) (i.e., two test 

conditions). A similar comment request was made 

for the LVD DBS test, if NHTSA decided to adopt 

those same higher test speeds (i.e., 70 and 80 kph 

(43.5 and 49.7 mph)) for the CIB LVD test. 

damage the SV during testing. In such 

instances, camera or radar sensors on 

the vehicle may become misaligned 

such that subsequent runs might not be 

representative of the vehicle condition 

at the time of first sale. Further, striking 

the vehicle test device might 

prematurely degrade the appearance of 

the device and modify its specifications, 

including in ways not immediately 

observable. As mentioned previously, 

damage to the test device might affect 

the radar cross section and may require 

a lengthy verification procedure to 

discover. As such, vehicle contact 

which does not result in immediate test 

failure may introduce repeatability 

concerns, time-consuming interruptions 

to testing, and higher costs. 

As mentioned in the March 2022 RFC 

notice, the Agency is not proposing a 

full-scale rating system for crash 

avoidance technologies at this time. 

NHTSA plans to continue to use check 

marks to give credit to vehicles that are 

equipped with the recommended ADAS 

technologies and pass the applicable 

system performance test requirements 

for each ADAS technology included in 

NCAP until it issues a final decision 

notice announcing the new ADAS rating 

system. Therefore, at this time, the 

Agency cannot adopt a points-based 

system for speed reductions, as Auto 

Innovators, HATCI, Toyota, and Rivian 

suggested. 

Regarding Toyota’s comment that 

adopting a speed reduction performance 

criterion could reduce the number of 

trials necessary for vehicle assessments 

and therefore reduce test burden, the 

Agency’s planned testing approach 

(discussed in the next section) will 

effectively address this concern. 

Finally, the Agency agrees with CAS 

that it will be easier to communicate test 

results to consumers if the passing 

criterion is straightforward (‘‘no 

contact’’) compared to a passing 

criterion based on speed reduction or 

maximum allowable impact speed. 

NHTSA also recognizes, as the 

respondent suggested, that full 

avoidance is likely the result that most 

consumers desire from an AEB system. 

e. Number of Trials 

Currently, NHTSA’s AEB test 

procedure requires that a vehicle meet 

performance criteria (i.e., a specified 

speed reduction) for five out of seven 

trials. In its March 2022 proposal, 

however, the Agency suggested that a 

new testing approach may be more 

appropriate given the changes proposed 

for its AEB tests. 

Per NHTSA’s March 2022 RFC, only 

one valid test trial (i.e., a trial in which 

all test specifications and tolerances are 

satisfied) would be conducted per each 

incremented test speed (i.e., 40, 50, 60, 

70, and 80 kph or 24.9, 31.1, 37.3, 43.5, 

and 49.7 mph (as applicable for each 

test scenario)) 127 as long as the SV did 

not contact the POV test device. If the 

SV were to contact the POV during a 

test trial, and the relative longitudinal 

velocity between the SV and POV was 

less than or equal to 50 percent of the 

initial speed of the SV, NHTSA 

proposed that it would then perform 

four additional (repeated) test trials at 

the same speed for which the impact 

occurred. The Agency proposed that the 

SV could not contact the POV for at 

least three out of the five test trials 

performed at that same speed to pass 

that specific combination of test 

scenario and test speed (i.e., test 

condition).128 If the SV contacted the 

POV during a valid trial of a test 

condition (whether it be the first test 

performed at a particular test speed or 

a subsequent test trial at that same 

speed), and the relative impact velocity 

exceeded 50 percent of the initial speed 

of the SV, no additional test trials would 

be conducted at the given test speed (or 

for the test scenario) and the SV would 

fail the test condition. 

Because the Agency had proposed 

additional test speeds (compared to its 

current assessments) for the various 

AEB test scenarios, NHTSA asserted this 

assessment approach would reduce test 

burden while continuing to ensure that 

passing AEB systems represent robust 

designs that offer a high level of 

performance and safety. In its March 

2022 RFC, the Agency sought comment 

on whether this proposed assessment 

method was appropriate or whether an 

alternative method, such as subjecting 

the vehicle to multiple trials, should be 

adopted instead. For respondents 

preferring multiple trials, NHTSA asked 

how many trials would be appropriate 

and what an acceptable pass rate would 

be. Further, for those respondents who 

favored the proposed assessment 

method, NHTSA asked whether such a 

method would also be acceptable in 

instances where only one or two test 

speeds were selected for inclusion, such 

as for the LVD test scenario,129 or 

whether it would be more appropriate 

in such instances to alternatively 

require seven trials for each test speed 

and additionally require that five out of 

the seven trials conducted pass the ‘‘no 

contact’’ performance criterion. 

Summary of Comments 

A few commenters generally agreed 

with the Agency’s proposal to conduct 

one trial per test speed with speed 

increments of 10 kph (6.2 mph) and to 

only perform repeated trials in the event 

of POV contact. Rivian was one such 

commenter, stating that the proposed 

AEB test method was ‘‘practical,’’ as 10 

kph (6.2 mph) test speed increments 

should sufficiently highlight 

performance degradations such that 

multiple trials at a given speed should 

not be necessary, thus reducing test 

burden. Likewise, IDIADA commented 

that performing one trial per test speed 

across many different speeds was 

sufficient to ensure system robustness. 

DRI also supported the Agency’s 

proposal for AEB testing, explaining 

that their experience has shown that CIB 

and DBS systems typically do not have 

difficulty detecting lead vehicles and 

are able to do so repeatedly such that 

inconsistent results generally stem from 

poor system performance rather than 

detection capabilities. 

HATCI and Honda also generally 

agreed with the Agency’s proposal. The 

manufacturers were in favor of 

completing an additional four runs after 

the first failed (i.e., contact) run and 

supported the proposed pass rate of 

three out of five total runs. However, 

Honda commented that additional trials 

should be conducted even if the AEB 

system does not impart a 50 percent 

relative speed reduction in the first trial 

run. The automaker expressed that 

stopping the test after one failed run 

may be ‘‘overly strict’’ and ‘‘premature’’ 

given potential variations in test 

conditions. 

BMW supported test speed 

increments of 10 kph (6.2 mph) and the 

Agency’s proposal to conduct four 

additional runs in the event of contact 

if NHTSA ultimately adopted a ‘‘no 

contact’’ (i.e., pass/fail) criterion. 

Having noted this, the automaker, along 


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with several other commenters, 

expressed strong support for adopting 

assessment criteria based on speed 

reduction instead. With speed reduction 

as the assessment criterion (instead of 

‘‘no contact’’), BMW supported 

conducting two additional trials after 

the first run failure (i.e., contact) and 

then using the median speed for all 

three trial runs as the true impact speed 

for rating purposes. 

Auto Innovators and FCA also 

generally supported the Agency’s 

proposal for AEB testing (i.e., one trial 

per test speed) but suggested that a pass 

rate of two out of three would be 

acceptable in instances of contact 

during the first trial run for a test 

condition to reduce test burden. 

However, like BMW, both groups also 

stated that the Agency should recognize 

the inherent safety benefits afforded by 

crash mitigation (i.e., speed reduction) 

in addition to complete crash 

avoidance. In the same vein, Auto 

Innovators asserted that the Agency’s 

current proposal, which would prohibit 

test conduct for higher speeds if lower 

speeds did not result in crash 

avoidance, ‘‘may unintentionally 

penalize systems that have robust 

higher-speed performance.’’ 

Accordingly, the group suggested that 

(1) conducting higher-speed trial runs 

should not be contingent on a 50 

percent relative speed reduction for 

lower speed runs and/or (2) testing for 

a scenario should continue regardless of 

whether the relative speed reduction in 

one trial is less than 50 percent. Instead, 

Auto Innovators suggested the Agency 

consider assigning ‘‘partial credit’’ to 

systems that perform worse at lower 

speeds. Whereas BMW recommended 

using the median speed of all three 

trials to assign vehicles’ AEB 

performance ratings, FCA suggested 

NHTSA average the impact speed for 

the trials conducted when impact 

occurs. FCA further noted it would 

prefer ‘‘further definition’’ for LVD tests 

at test speeds greater than 60 kph (37.3 

mph) before settling on an assessment 

method for these test conditions. 

In general, GM favored optimizing the 

number of test conditions rather than 

reducing the number of test runs. The 

manufacturer noted the former does 

more to reduce overall test burden and 

the latter leads to a diminished 

understanding of system performance 

variation. However, in this instance, the 

automaker reasoned that the Agency’s 

proposal would ‘‘speed up the test, and 

only repeat trials when necessary,’’ so 

they were supportive of the proposed 

three out of five pass rate if the Agency 

adopted a ‘‘no contact’’ performance 

criterion. However, the automaker, like 

many others, favored speed reduction as 

the performance criterion for higher 

speeds in lieu of ‘‘no contact.’’ More 

specifically, GM recommended the 

Agency adopt a 30 kph (18.6 mph) 

relative impact speed (instead of full 

avoidance) as the minimum 

performance criterion for SV speeds 

above 50 kph (31.1 mph). The 

manufacturer suggested that additional 

trials should be performed for those 

vehicles having a relative impact speed 

of 30 kph (18.6 mph) or less, and either 

the mean or median of the resulting 

velocity reductions should be used for 

scoring. 

While Rivian stated that the Agency’s 

proposal of testing across multiple 

speeds instead of multiple trials at the 

same speed would ensure system 

robustness, Intel stated that conducting 

multiple trials was ‘‘more robust.’’ 

However, to limit test burden, Intel 

suggested, like others, that a pass rate of 

two out of three trials was appropriate 

for a given test condition. The company 

also agreed in sentiment with others’ 

recommendation that the Agency 

recognize the safety benefits inherent to 

speed reductions, and Honda’s assertion 

that stopping a test because of one run 

at a lower speed that doesn’t produce at 

least a 50 percent speed reduction may 

be too extreme. As such, Intel also 

proposed an alternative test procedure 

to further reduce test burden. 

For its proposed procedure, Intel 

suggested that instead of performing the 

entire AEB test matrix, NHTSA should 

select a random subset of tests (i.e., test 

conditions) to be performed based on 

test results for the complete matrix 

provided by vehicle manufacturers. The 

first trial of the first selected test 

condition would then be performed. If 

the speed reduction for that trial meets 

a ‘‘predicted’’ speed reduction, points 

applicable to the actual speed reduction 

would be awarded and the first trial of 

the next randomly selected test 

condition would then be performed. If 

the speed reduction for the first trial 

was insufficient (i.e., did not achieve the 

‘‘predicted’’ speed reduction), an 

additional two trials would be 

conducted (as mentioned previously). If 

both of those trial runs achieved the 

‘‘predicted speed reduction,’’ points 

applicable to the actual speed reduction 

would be awarded and testing would 

continue with the next randomly 

selected test condition. If the 

‘‘predicted’’ speed reduction was not 

met for at least two of the three trials 

conducted for a given test condition, 

then the test would cease, and partial 

points would be awarded based on the 

average speed reduction recorded for 

the three trials. Intel also suggested the 

Agency should apply a penalty, as is 

done by Euro NCAP, for instances 

where the actual speed reduction is less 

than the ‘‘predicted’’ speed reduction. 

Tesla also stated it supported 

adopting performance criteria based on 

speed reduction in lieu of a ‘‘no 

contact’’ pass/fail criterion (for both CIB 

and DBS). Unlike the other commenters 

who expressed a similar sentiment and 

proposed that three trials should be 

conducted upon impact, Tesla 

supported the Agency’s original 

proposal of requiring that an additional 

four runs be conducted after the initial 

trial run (for five runs total). For those 

additional four runs, Tesla asserted the 

vehicle should have to achieve a speed 

reduction of 75 percent or more of the 

initial SV speed to obtain a passing 

result for that test condition. If the 

vehicle was to achieve passing results 

for that test condition, then the speed 

would be incremented to the next test 

speed and the process would repeat 

until the vehicle either could not exceed 

a 75 percent speed reduction, or the 80 

kph (49.7 mph) test condition was 

passed, whichever came first. 

CAS stated that NHTSA’s assessments 

should be based on objective reliability 

and confidence criteria, noting that 

passing 7 out of 7 trials at any speed 

provides 91 percent reliability of the 

AEB system with only 50 percent 

confidence. Therefore, CAS contended 

that no fewer than 7 successful trials 

and no failures should be acceptable at 

any speed. 

As previously mentioned, Auto 

Innovators did not favor a pass rate of 

five out of seven runs since this pass 

rate would not optimize test resources. 

Notwithstanding, the group remarked 

that if the Agency did impose a five out 

of seven requirement and the first five 

runs produced passing results (i.e., no 

contact), then the last two runs should 

not be conducted in order to reduce test 

burden. 

Other commenters provided general 

comments on this topic. For example, 

Toyota stated the Agency should 

conduct the number of trials that were 

sufficient to communicate accurate 

performance information to consumers, 

without recommending a specific 

number. Advocates asserted that the 

Agency should justify how the number 

of trials and pass/fail criteria adopted 

will assure that evaluated systems will 

perform as expected and address the 

safety need, especially since NHTSA’s 

testing is conducted under controlled 

conditions. 


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130The Agency will increment test speeds by 10 

kph (6.2 mph) from a minimum to a maximum 

speed. 

131Three hundred trials would be needed for 99 

percent reliability with 95 percent confidence. 

Similarly, 59 trials would be needed for 95 percent 

reliability with a 95 percent confidence, and 29 

trials would be needed for 90 percent reliability 

with 95 percent confidence. 

132Since the vehicle tested is randomly 

purchased or leased from dealerships, its 

performance in the AEB tests is based on the 

performance and manufacturing reliability set by 

the manufacturer. 

Response to Comments and Agency 

Decisions 

The Agency sought feedback on the 

proposed number of trials within each 

test variant. The Agency also asked 

commenters to consider a potential 

ADAS rating system that would allow 

flexibilities for continuous 

improvements to the program and crossmodel year comparisons. Based on 

comments received on the appropriate 

number of trials for each test variant, 

NHTSA has decided that instead of 

performing multiple trials for each 

assessed test condition for a given test 

scenario, as is currently done for NCAP 

testing, it will conduct one trial per test 

condition (e.g., at a prescribed test 

speed for a given test condition/ 

scenario) for future AEB NCAP tests. In 

the event the SV contacts the POV 

during a trial, testing will cease for the 

test condition, respective test scenario, 

and the AEB test being performed (i.e., 

CIB or DBS). Effectively, the vehicle will 

fail the individual test condition/ 

scenario being assessed, and it will not 

receive NCAP credit for the ADAS 

system being evaluated, whether it be 

CIB or DBS. 

Number of Trials Required for Each Test 

Condition 

Since the Agency will run only one 

valid trial per test condition, per 

NHTSA’s finalized CIB testing 

approach, the Agency will conduct, at 

most, five LVS tests, five LVM tests, 

eight LVD tests, and one false positive 

test. For DBS, NHTSA will conduct, at 

most: four LVS tests, four LVM tests, 

eight LVD tests, and one false positive 

test. This results in a maximum total of 

19 CIB test trials and 17 DBS test trials, 

or 36 total AEB trials. 

Although several commenters, like 

Intel and CAS, stated the Agency should 

or must continue to conduct multiple 

trials per test condition, many other 

commenters (Auto Innovators, FCA, 

GM, HATCI, Honda, and BMW) asserted 

that NHTSA’s planned testing approach 

was appropriate. There are several 

reasons that a testing approach requiring 

one trial run per test condition, instead 

of multiple runs, is appropriate for the 

Agency’s AEB testing in NCAP. First, 

NHTSA notes that DRI attested that, 

from its own experience with AEB 

testing, systems exhibiting better 

performance tend to do so repeatably. 

DRI’s observation for superior AEB 

systems partially counters CAS’s 

assertion that conducting a single trial 

for a given test condition would be 

insufficient. With respect to less robust 

AEB systems, the Agency acknowledges 

that, occasionally, a vehicle may pass 

the first trial for a given speed even 

though it may fail subsequent trials if 

additional trials were to be conducted at 

that same speed. However, NHTSA also 

asserts that the system’s poor 

performance could alternatively be 

exposed in single trials conducted for 

progressively higher speeds, which is 

the approach the Agency has adopted 

for its LVS and LVM tests.130 As such, 

the Agency agrees not only with 

IDIADA, which stated that an approach 

that requires one trial per test speed 

across many different speeds should 

effectively assure system robustness, but 

also with Rivian, which noted that such 

an approach should effectively identify 

changes in system performance without 

the need to conduct multiple runs for 

each test condition. Further, NHTSA 

asserts its planned testing approach of 

incrementing test speeds should also 

reduce the risk of damage to the SV and 

POV. 

Performing one trial run per test 

condition is also reasonable for NCAP’s 

LVD tests. Although NHTSA plans to 

assess only two discrete test speeds for 

the LVD scenario rather than a range of 

speeds as planned for the LVS and LVM 

scenarios, NHTSA reasons this 

approach should still ensure system 

robustness for the LVD AEB tests. As 

mentioned earlier, since the SV and 

POV speeds are initially the same in the 

LVD tests, the initial speed conditions 

for the decelerating lead vehicle 

scenario are not as critical to the 

outcome of the test as the other main 

parameters, headway and POV 

deceleration. It should be noted, though, 

that a higher initial test speed 

inherently requires additional braking to 

achieve a complete stop compared to a 

lower initial test speed. Thus, by 

adopting two discrete test speeds, two 

different headways, and two POV 

deceleration magnitudes, as well as 

structuring testing such that it 

progresses from generally the least 

challenging to the most challenging 

parameters, it will still ensure AEB 

systems receiving NCAP credit for 

passing test results represent robust 

designs offering a high level of 

performance and safety without 

increasing test burden unnecessarily. 

Second, NHTSA’s testing approach is 

reasonable for NCAP because it best 

manages test burden. Per CAS’ 

comments, the Agency can only be 50 

percent confident that AEB systems will 

be 91 percent reliable when seven runs 

are conducted for each test condition. 

This means that NHTSA would have to 

perform a far greater number of runs for 

each test condition to have a reasonably 

high confidence that the observed 

system performance is representative of 

the system’s true capability.131

Alternatively, the Agency could 

consider conducting a large number of 

runs at only the highest test speed for 

each test scenario. However, it would 

risk imparting additional damage to the 

test vehicle and test equipment in 

addition to test delays due to repairs if 

it were to take such an approach.132

Third, permitting some number of 

failures, which would be inherent to 

repeated trials, would be detrimental to 

real-world safety. Considering NCAP 

testing will be limited to only certain 

conditions in a controlled testing 

environment, allowing no test failures is 

the most acceptable approach and will 

best ensure consistency in real world 

AEB system performance and safety 

improvement in rear-end crashes. 

The aforementioned considerations 

make the Agency’s planned testing 

approach the most appropriate for 

NCAP testing. Because NHTSA has 

decided to adopt an approach requiring 

only one trial per test condition, it is not 

necessary to evaluate a random subset of 

test conditions to limit test burden, as 

Intel suggested. 

Repeat Trials in the Event of Contact 

NHTSA’s RFC notice proposed 

performing four additional (repeated) 

test trials at the same test speed if the 

SV contacted the POV during the first 

test trial for a given AEB test condition 

and the relative longitudinal velocity 

between the SV and POV was less than 

or equal to 50 percent of the initial 

speed of the SV. To pass the test 

condition, NHTSA proposed that the SV 

could not contact the POV for at least 

three out of the five total trials 

conducted. The Agency also proposed 

that if the SV contacted the POV during 

a valid trial of a test condition (whether 

it be the first test performed at a 

particular test speed or a subsequent 

repeat run conducted at that same 

speed), and the relative longitudinal 

impact velocity exceeded 50 percent of 

the initial speed of the SV, no additional 

test trials would be conducted at the 

given test speed (or for the test scenario) 

and the SV would fail the test condition. 


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133https://downloads.regulations.gov/NHTSA2023-0021-0006/attachment_2.pdf. 

The Agency has decided not to finalize 

this part of its proposal and will thus 

not conduct repeat trials in the event of 

SV-to-POV contact, regardless of the 

relative longitudinal impact velocity 

recorded between the two vehicles at 

the time of impact. 

Many commenters (Auto Innovators, 

BMW, FCA, GM, HATCI, Honda, Rivian, 

and Tesla) agreed, at least in part (some 

differed on the pass rate), with the 

Agency’s proposal to conduct additional 

trials if an initial trial run resulted in 

contact, and most of these commenters 

(Auto Innovators, BMW, FCA, GM, 

Honda, and Rivian) stated that NHTSA 

should consider conducting multiple 

trials regardless of whether a 50 percent 

speed reduction was observed in the 

first or subsequent trial runs. However, 

based on other comments received and 

laboratory testing experience, NHTSA 

reasons it is no longer appropriate to 

conduct repeat trials in the event of 

contact. 

Specifically, the Agency’s underlying 

objective in updating NCAP is to adopt 

AEB tests that are representative of realworld rear-end crashes and maximize 

safety. To achieve these goals, NHTSA 

must establish performance criteria for 

testing that will ensure AEB system 

response is consistent and repeatable. 

Similar to DRI’s observations during 

AEB testing, the Agency has observed 

that if a vehicle contacts the vehicle test 

device during the first trial run for a test 

condition, it is also likely to contact the 

vehicle test device during subsequent 

runs conducted.133 In the Agency’s 

testing, if an impact occurred and 

additional tests were performed for that 

test condition, at least one more impact 

was observed 97 percent of the time (32 

of 33 applicable test conditions) for CIB 

tests, and for 100 percent of the DBS 

tests (27 of 27 of the applicable test 

conditions). Considering all CIB and 

DBS trials, the total was 98 percent (59 

of 60 total trials). Therefore, the Agency 

disagrees with commenters who stated 

that discontinuing testing after a singlerun failure is ‘‘overly strict.’’ 

Encouraging robust system 

performance that limits contact will 

lead to a reduction of harm and costs 

associated with crashes, and result in 

fewer testing delays and costs caused by 

SV-to-POV contact, benefiting both the 

public and the Agency. Based on this, 

NHTSA does not agree with concerns 

raised by several commenters who 

expressed that discontinuing testing 

after failures at low speeds may be 

‘‘premature’’ or may unfairly penalize 

vehicles that offer more robust AEB 

system performance at higher test 

speeds. Specifically, NHTSA notes that 

a lower speed rear-end crash resulting 

in an injury still causes an unnecessary 

injury, and still imposes an economic 

cost. As such, requiring crash avoidance 

performance across the range of speeds 

and test conditions defined in the NCAP 

AEB test matrix is imperative to 

maximize safety. 

The Agency also agrees with Toyota 

that it should only conduct the number 

of test trials necessary to provide 

consumers with accurate information 

pertaining to AEB system performance. 

Allowing repeated trials in the event of 

SV-to-POV contact may mislead 

consumers, potentially causing them to 

assume that a vehicle’s AEB system 

provides more repeatable, robust crash 

avoidance performance than it does. As 

such, it is most appropriate to provide 

consumers with an assessment of 

system performance using a single, 

representative sample rather than an 

assessment based on the average or 

median impact speed across several 

runs, as some commenters suggested. 

Manufacturers must design their 

vehicles to meet the adopted 

performance criteria every time. By 

proceeding in this manner, the Agency 

is responding to Advocates’ request to 

best ensure the number of trial and 

performance criteria adopted will assure 

that evaluated systems will perform as 

expected and best address the safety 

need. 

f. Pass Rate 

The Agency sought comment on an 

appropriate minimum pass rate to 

evaluate AEB performance based on the 

adjustments it proposed for its AEB 

assessments. The proposal included 

plans to (1) consolidate its FCW and CIB 

tests such that the CIB tests would also 

serve as an indicant of FCW operation, 

(2) assess up to 14 test speeds for CIB 

(i.e., five for LVS, five for LVM, and 

potentially four for LVD), and (3) assess 

up to six test speeds for DBS (two for 

LVS, two for LVM, and potentially two 

for LVD), which would result in a total 

of up to 20 unique combinations of test 

conditions to be evaluated for AEB. As 

an example, the Agency suggested that 

a vehicle could be considered to meet 

the AEB performance if it passes twothirds of the 20 unique combinations of 

test conditions (i.e., passes 14 unique 

combinations of test conditions). 

Summary of Comments 

Bosch favored a pass rate of twothirds of the 20 unique combinations 

but stated that any vehicles not able to 

meet this criterion should be awarded 

partial credit. BMW, Honda, and Auto 

Innovators also commented that a pass 

rate of two-thirds is reasonable. 

However, to ensure that both CIB and 

DBS performance is weighted equally, 

Honda suggested (as mentioned earlier) 

that the Agency should add DBS tests at 

lower speeds (40, 50, and 60 kph) to 

align with CIB performance evaluations 

that are also conducted at those speeds. 

Tesla favored a pass rate of 70 percent 

for CIB and DBS tests overall (i.e., 70 

percent of all test conditions assessed 

for the specified test scenarios) since 

this would generally be consistent with 

current NCAP test procedures, which 

require a pass rate of five out of seven 

trials. 

CAS asserted that the only 

appropriate pass rate is 100 percent, 

stating that the number of trials 

proposed by the Agency was 

‘‘insufficient to establish high 

confidence in safe performance even 

with no failures.’’ 

Response to Comments and Agency 

Decisions 

NHTSA has decided to adopt a 100 

percent pass rate for CIB and DBS 

system testing and will provide 

consumers with an overall assessment 

of AEB performance, as proposed. This 

means AEB systems must achieve 

passing results (i.e., no POV-to-SV 

contact) in all adopted test conditions 

for both CIB and DBS (i.e., 19 test 

conditions for CIB—five for LVS, five 

for LVM, eight for LVD, and one false 

positive; and 17 test conditions for 

DBS—four for LVS, four for LVM, eight 

for LVD, and one false positive) to 

receive credit for AEB technology. The 

Agency will not provide separate credit 

for CIB and DBS passing performance; 

only those vehicles achieving passing 

performance for all 36 AEB test 

conditions will receive NCAP credit for 

passing AEB performance. 

The Agency’s decision to adopt a pass 

rate of 100 percent and combine CIB 

and DBS performance into an overall 

assessment for AEB is appropriate for 

several reasons. First, NHTSA agrees 

with CAS that no test failures should be 

allowed for any test scenarios/ 

conditions. This is the best way to 

ensure that only the most robust AEB 

systems obtain AEB credit on the 

Agency’s website. Adopting a pass rate 

of two-thirds or seventy percent, as 

some commenters suggested, or 

awarding partial credit, as Bosch 

requested, does not best serve the 

motoring public. As mentioned 

previously, the only way to ensure AEB 

systems afford meaningful safety is to 

require vehicles to avoid contact for 

every test condition assessed. Further, 

since the goal of NCAP is to provide 


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95954 Federal Register / Vol. 89, No. 232 / Tuesday, December 3, 2024 / Notices 

134National Highway Traffic Safety 

Administration (2012, June), Forward-looking 

advanced braking technologies research report, 

https://www.regulations.gov/document?D=NHTSA2012-0057-0001. 

135National Highway Traffic Safety 

Administration. (2023, February). NHTSA’s 2022 

Light Vehicle Automatic Emergency Braking 

Research Test Summary. http://

www.regulations.gov. Docket No. NHTSA–2023– 

0021–0005. This statement is based on the results 

of the Agency’s model year 2021–2022 research test 

data, which did not include the LVD test conditions 

that require a 0.3g POV deceleration. 

consumers with information to inform 

their vehicle buying choices, 

communicating information on the 

functionality of a vehicle’s entire AEB 

system, rather than its individual 

system components, would be more 

beneficial at this time. The Agency 

reasons that consumers’ new vehicle 

selection criteria will not include a 

consideration of whether they anticipate 

braking or not when faced with a crashimminent situation. Rather, they will 

want to purchase a vehicle that 

responds appropriately to prevent the 

crash regardless of their action(s) or 

inaction. As such, providing separate 

ratings for CIB and DBS performance 

would be unhelpful in this regard. 

NHTSA also does not want to mislead 

consumers in assuming AEB system 

performance is better than it is by 

assigning credit to a vehicle for passing 

DBS performance when its CIB 

performance was lackluster. This is 

particularly concerning since, as 

mentioned, NHTSA found in its 

analysis of 2003–2009 NASS–CDS data 

that drivers of an SV involved in a rearend crash tended to brake at about the 

same rate as those who did not brake, 

thus making performance for both 

system components equally 

important.134 Yet, the Agency’s research 

testing for model year 2021–2022 

vehicles suggested that no vehicle 

exhibited passing performance for both 

AEB technologies, although one vehicle 

achieved passing results for one 

technology, DBS.135 Nonetheless, 

NHTSA believes that achieving a pass 

rate of 100 percent for CIB and DBS 

testing is feasible. The Agency notes 

that the vehicle which provided passing 

performance for all DBS tests also 

achieved no contact performance for 16 

of the 18 assessed CIB test conditions. 

While contact was observed for the 12 

m headway, 0.4g deceleration LVD CIB 

test condition (such that the 12 m 

headway, 0.5g deceleration LVD CIB test 

condition was not subsequently 

performed), the vehicle exhibited a 

relative impact speed of less than 10 

kph during all runs performed. 

Considering the vehicle’s robust 

performance overall for the 

overwhelming majority of the AEB tests 

conducted, NHTSA believes that minor 

changes to the system’s software should 

afford a perfect pass rate overall. 

Since the number of tests adopted for 

NCAP’s CIB assessments is nearly 

identical to the number adopted for the 

program’s DBS assessments (i.e., 19 tests 

for CIB versus 17 for DBS), there is no 

need to weight either set of assessments 

(i.e., those for CIB or DBS), as Honda 

requested, especially since vehicles 

must achieve a pass rate of 100 percent 

for each of the two AEB technologies to 

receive credit for both. 

An overview of test scenarios and 

conditions that will be required to 

receive passing credit for AEB systems 

in NCAP is shown in Tables 14 and 15. 

TABLE 14—ADOPTED CIB TEST SCENARIOS AND CONDITIONS

Test No. Test scenario SV speed 

(kph (mph)) 

POV speed 

(kph (mph)) 

POV 

headway 

(m (ft.)) 

POV 

deceleration 

(g) 

Requirement to pass 

1 ............. LVS .................................. 40 (24.9) 0 n/a n/a No SV-to-POV contact during any trial. 

2 ............. 50 (31.1) 0 n/a n/a 

3 ............. 60 (37.3) 0 n/a n/a 

4 ............. 70 (43.5) 0 n/a n/a 

5 ............. 80 (49.7) 0 n/a n/a 

6 ............. LVM ................................. 40 (24.9) 20 (12.4) n/a n/a 

7 ............. 50 (31.1) 20 (12.4) n/a n/a 

8 ............. 60 (37.3) 20 (12.4) n/a n/a 

9 ............. 70 (43.5) 20 (12.4) n/a n/a 

10 ........... 80 (49.7) 20 (12.4) n/a n/a 

11 ........... LVD .................................. 50 (31.1) 50 (31.1) 40 (131.2) 0.3 

12 ........... 50 (31.1) 50 (31.1) 12 (39.4) 0.3 

13 ........... 80 (49.7) 80 (49.7) 40 (131.2) 0.3 

14 ........... 80 (49.7) 80 (49.7) 12 (39.4) 0.3 

15 ........... 50 (31.1) 50 (31.1) 40 (131.2) 0.5 

16 ........... 50 (31.1) 50 (31.1) 12 (39.4) 0.5 

17 ........... 80 (49.7) 80 (49.7) 40 (131.2) 0.5 

18 ........... 80 (49.7) 80 (49.7) 12 (39.4) 0.5 

19 ........... False Positive (STP) ........ 80 (49.7) n/a n/a n/a SV peak deceleration <0.25g. 

TABLE 15—ADOPTED DBS TEST SCENARIOS AND CONDITIONS

Test No. Test scenario SV speed 

(kph (mph)) 

POV speed 

(kph (mph)) 

POV 

headway 

(m (ft.)) 

POV 

deceleration 

(g) 

Requirement to pass 

1 ............. LVS .................................. 70 (43.5) 0 n/a n/a No SV-to-POV contact during any trial. 

2 ............. 80 (49.7) 0 n/a n/a 

3 ............. 90 (55.9) 0 n/a n/a 

4 ............. 100 (62.1) 0 n/a n/a 

5 ............. LVM ................................. 70 (43.5) 20 (12.4) n/a n/a 

6 ............. 80 (49.7) 20 (12.4) n/a n/a 

7 ............. 90 (55.9) 20 (12.4) n/a n/a 

8 ............. 100 (62.1) 20 (12.4) n/a n/a 

9 ............. LVD .................................. 50 (31.1) 50 (31.1) 40 (131.2) 0.3 


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Federal Register / Vol. 89, No. 232 / Tuesday, December 3, 2024 / Notices 95955 

136 80 FR 68604 (Nov. 5, 2015). 

137ABD refers to their GVT product as the ‘‘Soft 

Car 360’’ and 4activeSystems refers to their GVT 

product as the ‘‘4activeC2.’’ 

138Snyder, A.C., Forkenbrock, G.J., Davis, I.J., 

O’Harra, B.C., & Schnelle, S.C., A test track 

comparison of the global vehicle target and 

NHTSA’s strikeable surrogate vehicle, (Report No. 

DOT HS 812 698), July 2019, https://

rosap.ntl.bts.gov/view/dot/41936. 

139 Id. 

140https://www.euroncap.com/en/for-engineers/ 

supporting-information/technical-bulletins/. See 

Appendices I & II. 

141Currently, manufacturers use test results from 

their internal testing and submit them to NHTSA 

for NCAP’s recommendation of vehicles that pass 

its performance testing requirements. 142FCW and CIB onset timings for a given vehicle 

model were found to be highly comparable in the 

Agency’s CIB characterization testing regardless of 

whether the SSV or ABD GVT vehicle test device 

was used. NHTSA notes that ABD GVT Revision E 

was used for these assessments. 143Snyder, A.C., Forkenbrock, G.J., Davis, I.J., 

O’Harra, B.C., & Schnelle, S.C., A test track 

comparison of the global vehicle target and 

NHTSA’s strikeable surrogate vehicle, (Report No. 

DOT HS 812 698), July 2019, https://

rosap.ntl.bts.gov/view/dot/41936. 

TABLE 15—ADOPTED DBS TEST SCENARIOS AND CONDITIONS—Continued 

Test No. Test scenario SV speed 

(kph (mph)) 

POV speed 

(kph (mph)) 

POV 

headway 

(m (ft.)) 

POV 

deceleration 

(g) 

Requirement to pass 

10 ........... 50 (31.1) 50 (31.1) 12 (39.4) 0.3 

11 ........... 80 (49.7) 80 (49.7) 40 (131.2) 0.3 

12 ........... 80 (49.7) 80 (49.7) 12 (39.4) 0.3 

13 ........... 50 (31.1) 50 (31.1) 40 (131.2) 0.5 

14 ........... 50 (31.1) 50 (31.1) 12 (39.4) 0.5 

15 ........... 80 (49.7) 80 (49.7) 40 (131.2) 0.5 

16 ........... 80 (49.7) 80 (49.7) 12 (39.4) 0.5 

17 ........... False Positive (STP) ........ 80 (49.7) n/a n/a n/a SV peak deceleration <0.25g over the baseline peak imparted by manual braking. 

g. Use of the ABD GVT and Appropriate 

Revision(s) 

Currently, NHTSA uses the SSV as 

the POV in NCAP testing of DBS and 

CIB systems. The SSV, modeled after a 

small hatchback passenger car, is 

fabricated from light-weight composite 

materials including carbon fiber and 

Kevlar®.136 To maximize visual realism, 

the SSV shell is wrapped with a vinyl 

material that simulates paint on the 

body panels and rear bumper and a 

tinted glass rear window. Given the 

combination of a design that emphasizes 

being lightweight, use of a towed track 

to support movement, and its material 

properties, the SSV has certain 

limitations during testing; namely, the 

maximum speed at which it can operate 

(i.e., ≤56 kph (35 mph)) and maximum 

relative speed at which the SV can 

strike it (i.e., 40 kph (25 mph) and lower 

speed). When operated outside of its 

intended operational constraints, the 

SSV can inflict damage to other vehicles 

and/or be damaged itself. The monorail 

used to laterally constrain the SSV is 

visible and secured to the test surface, 

which could potentially confound 

camera-based AEB systems. Considering 

these complications and constraints for 

testing, NHTSA proposed in its March 

2022 RFC notice to use a GVT, mounted 

to a robotic platform, in lieu of the SSV 

in future AEB testing because GVTs do 

not have the same testing limitations. 

A GVT, which also resembles a white 

hatchback passenger car, is meant to 

represent a vehicle in the subcompact to 

compact car class. A specific 

description of the required GVT 

characteristics is defined in 

International Organization for 

Standardization (ISO) 19206–3:2021, 

and at the time of this notice, there were 

two companies that produced a GVT as 

a commercially available product: AB 

Dynamics, Inc (ABD) and 

4activeSystems (4a).137 Both versions 

use an internal foam-based frame 

covered by multiple vinyl outer ‘‘skin’’ 

sections designed to provide the 

dimensional, optical, and radar 

characteristics of a real vehicle that can 

be recognized as such by camera and 

radar sensors.138 In contrast to the SSV, 

the available GVTs are secured using 

hook and loop fasteners to the top of a 

programmable robotic platform which 

facilitates their movement. When either 

version of the GVT is impacted at low 

speed, it is typically pushed off the 

robotic platform but remains assembled. 

At higher impact speeds, the ABD GVT 

breaks apart, as the SV essentially drives 

through it.139 At similar impact speeds, 

the 4a GVT is designed to remain more 

intact after being pushed off the robotic 

platform. Both GVT variants are 

designed to be reconstructed/reset back 

on top of the robotic platform after an 

SV-to-POV impact occurs. NHTSA 

reasoned that a GVT is therefore less 

likely than the SSV to impart damage to 

other vehicles, particularly at higher 

impact speeds. 

In its March 2022 RFC notice, NHTSA 

proposed to use the [ABD] GVT 

Revision G for its future AEB 

assessments. This vehicle test device 

was proposed at the time because it is 

currently used by other consumer 

vehicle safety organizations that provide 

consumer information, including Euro 

NCAP,140 as well as many vehicle 

manufacturers in their internal testing 

conducted per NCAP test 

specifications.141 As such, by adopting 

ABD GVT Revision G for NCAP’s AEB 

testing, NHTSA would embrace another 

opportunity to harmonize with other 

consumer information safety rating 

programs, as mandated by the BIL. The 

Agency also noted that the ABD GVT 

would be an appropriate replacement 

for the SSV in NCAP’s future AEB 

testing because the test device (1) 

afforded similar AEB system 

performance to that of the SSV in 

comparison testing,142 and (2) was 

found to be physically stable and 

durable when evaluated using straight 

line and curved path maneuvers for 

various speeds and lateral 

accelerations.143 Accordingly, the 

Agency reasoned that the ABD GVT 

Revision G could be used to evaluate 

more challenging crash scenarios in 

future NCAP upgrades as well, such as 

those required for other ADAS 

technologies (intersection safety assist 

(intersection AEB) and Opposing Traffic 

Safety Assist (OTSA)), which would 

allow harmonization across the program 

areas. NHTSA did not similarly propose 

adoption of the 4a GVT because it had 

not yet evaluated the in-use 

characteristics of the device as part of its 

AEB research. 

The Agency, recognizing that there 

have been ongoing revisions to the ABD 

GVT to address its performance in other 

crash modes that exercise different 

ADAS applications, proposed to adopt 

the latest revision of the test device, 

Revision G, for NCAP’s AEB testing. 


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144To improve the real-world characteristics from 

the front and side of the vehicle test device, several 

changes to the radar treatment were integrated into 

the components of the body for ABD GVT Revision 

G compared to ABD GVT Revision F, including 

changes to the skin and wheel treatment. There 

were also some minor shape changes to the front 

of the GVT body to improve front radar return and 

to the side to improve the ability to hold its shape. 

http://www.dynres.com/2020/02/25/the-new-globalvehicle-target-gvt-has-arrived/. 

145 It is the Agency’s understanding that the 

modifications made to the rear of ABD GVT 

Revision E consisted of adding additional radarabsorbing material to the bottom skirt of the vehicle 

test device to attenuate internal reflections and 

reducing the slope of the simulated rear hatchback 

glass to increase the power of the radar return from 

the rear aspect. 

146 80 FR 68604 (Nov. 5, 2015). 

147Mercedes-Benz requested that NHTSA 

consider several vehicle test devices and allow 

manufacturers the option to choose which test 

device is used for testing. 

148While not specifically mentioned in most 

comments, NHTSA assumes (unless otherwise 

indicated) responses to this topic pertained to the 

ABD GVT Revision G, as proposed. 

149 ISO/AWI 19206–3:2021, ‘‘Road vehicles—Test 

devices for target vehicles, vulnerable road users 

and other objects, for assessment of active safety 

functions—Part 3: Requirements for passenger 

vehicle 3D targets.’’ 

NHTSA reasoned that this latest 

revision could be utilized for other 

ADAS technologies proposed for 

adoption as part of this NCAP upgrade, 

such as blind spot intervention (BSI), as 

well as future technologies, such as 

intersection safety assist (ISA) and 

opposing traffic safety assist (OTSA). 

For AEB testing purposes only, NHTSA 

proposed to accept manufacturer 

verification data for AEB tests 

conducted using ABD GVT Revision F 

as well. It is the Agency’s understanding 

that modifications to the front, side, and 

oblique aspects of ABD GVT Revision F 

were incorporated into the company’s 

GVT Revision G. NHTSA reasoned that 

these changes should not alter the 

physical characteristics of the rear of the 

vehicle test device such that a vehicle’s 

performance in the rear-end crash mode 

(i.e., AEB testing) would be impacted.144

Though the Agency used ABD GVT 

Revision E in its comparison testing 

with the SSV, it is unclear if/how the 

small changes made to Revision E to 

create Revision F may have affected the 

test track AEB performance.145 For this 

reason, NHTSA did not propose to 

similarly accept manufacturer data for 

AEB test results derived using ABD GVT 

Revision E since this revision is no 

longer in production. Further, NHTSA 

also did not propose to accept vehicle 

manufacturer test data derived from 

alternative vehicle test devices other 

than that which is specified in NCAP’s 

test procedures, though this was 

requested in response to NHTSA’s 

November 2015 AEB final decision 

notice.146 147 The Agency explained that 

during its system performance 

verification testing it has observed 

several test failures that may be 

attributed to differences in vehicle test 

device designs. Therefore, NHTSA 

proposed to only accept manufacturer 

self-reported data obtained using tests 

conducted in accordance with NHTSA 

test procedures. 

Comments were sought on the 

adoption of the ABD GVT Revision G in 

lieu of the SSV for AEB testing in NCAP 

regardless of whether modifications 

were made to test speeds, deceleration, 

test scenarios, combining test 

procedures, et cetera. The Agency also 

requested comment on whether ABD 

GVT Revision G was the most 

appropriate for adoption, and whether 

ABD GVT Revisions F and G should be 

considered equivalent for AEB testing. 

Summary of Comments 

Use of the ABD GVT Revision G in Lieu 

of the SSV 

Commenters who supported replacing 

the SSV with the ABD GVT Revision 

G 148 in NCAP testing included AAA, 

Adasky, Auto Innovators, BMW, Bosch, 

CAS, GM, HATCI, Honda, IDIADA, 

MEMA, Rivian, Subaru, Toyota, and ZF 

Group. 

ZF Group stated it supported 

adoption of the GVT because it was 

developed through coordinated efforts. 

Several commenters, including ZF 

Group, HATCI, Honda, and GM, stated 

the GVT more reasonably simulates the 

characteristics (e.g., appearance, 

camera/radar detection, etc.) of actual 

vehicles. Auto Innovators noted that 

NHTSA participated in the GVT’s 

development and 360-degree correlation 

to real-world vehicles but has yet to 

adopt it for use in its testing. 

Toyota, GM, and Auto Innovators 

approved the use of the GVT because of 

its design and inherent durability. The 

commenters mentioned that the GVT is 

both less susceptible to damage 

compared to the SSV and less likely to 

induce damage to the SV, which 

naturally improves test efficiency and 

lowers testing costs. HATCI agreed that 

the GVT would limit damage to the SV 

and, along with Auto Innovators, 

asserted that it would promote a safer 

testing environment. 

Intel encouraged NHTSA to adopt the 

GVT because the Agency showed that 

performance differences between the 

two vehicle test devices were 

‘‘negligible’’ and real-world data has not 

revealed negative consequences due to 

its use. Furthermore, the company, 

along with Auto Innovators, Rivian, 

HATCI, Honda, and Adasky, favored the 

GVT’s adoption because it would 

harmonize with Euro NCAP and other 

consumer programs, which Rivian 

specifically asserted would permit 

consistency in testing and reduce 

overall test burden and costs. Bosch 

supported adopting the GVT because it 

is specified in International 

Organization for Standardization 

Approved Work Item (ISO/AWI) 19206– 

3:2021.149 Auto Innovators further 

added that the GVT would improve 

repeatability for LVD tests. IDIADA 

suggested that the SSV was ‘‘obsolete,’’ 

and GM and Auto Innovators mentioned 

that it had limited functionality (i.e., it 

is acceptable only for rear-end tests with 

no offset or angular requirements). CAS 

agreed with the sentiment expressed by 

these last two commenters and asserted 

that the GVT should replace the SSV 

because it will allow the Agency to 

perform higher speed tests and 

additional crash scenarios, as well as 

accommodate testing for other ADAS 

technologies, which will promote more 

safety. 

DRI mentioned that the GVT should 

be used in rear-end tests with 100 

percent overlap when closing speeds 

exceed 40.2 kph (25 mph); however, the 

laboratory asserted that the SSV remains 

appropriate for testing (and offers 

equivalent results to the GVT) at closing 

speeds of 40.2 kph (25 mph) or less. 

TRC expressed similar sentiments. 

HATCI also recognized the SSV’s 

viability for lower speed rear-end testing 

but argued that since it is limited to low 

speed rear-end tests, whereas the GVT 

can accommodate higher speeds and 

additional AEB and other ADAS 

technology test scenarios, the SSV 

should ideally be replaced with the GVT 

in NHTSA testing. Auto Innovators and 

GM agreed with HATCI but suggested it 

would be appropriate to ‘‘adopt a phasein approach’’ for replacement of the SSV 

with the GVT since some manufacturers 

may currently be using the SSV for 

testing. Both Auto Innovators and GM 

suggested that NHTSA accept test data 

derived using either vehicle test device 

for a period of time. 

In addition to their recommendation 

that the Agency adopt the GVT, Subaru 

and Auto Innovators requested that 

NHTSA harmonize with Euro NCAP 

with respect to the GVT moving 

platform, a GST100/120 or 4activeFBLarge, manufactured by ABD and 4a, 

respectively, in addition to adopting the 

related version of the GVT, to limit the 

cost burden to manufacturers. 


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150https://www.iso.org/standard/70133.html. 

May 2021. 

Consideration of Other ABD GVT 

Revisions and Alternative GVTs 

Some commenters supported only 

adoption of Revision G of the ABD GVT 

at this time, including BMW, Bosch, 

MEMA, Toyota, and ZF Group. BMW 

recommended use of the ABD GVT 

Revision G to harmonize with other 

consumer testing programs, including 

Euro NCAP. As mentioned previously, 

Intel also supported efforts to harmonize 

where possible. IDIADA was another 

commenter to support using ABD GVT 

Revision G for NCAP’s AEB testing. 

IDIADA opined that ABD GVT Revision 

G is the current standard version and 

‘‘offers more stable detection.’’ Similar 

to its prior comments for use of the GVT 

in general, Bosch stated that ABD GVT 

Revision G was appropriate to 

incorporate because it fulfills ISO/AWI 

19206–3:2021 requirements; however, 

the commenter also suggested that 

NHTSA refer to the ISO standard for 

incorporation rather than a GVT 

revision to allow for more flexibility in 

market participation. 

Several commenters expressed 

support for ABD GVT Revision G in 

addition to ‘‘lower’’ ABD GVT revisions 

(i.e., E, F) at this time. Auto Innovators, 

CAS, DENSO, DRI, FCA, GM, HATCI, 

Honda, Subaru, and TRC all opined that 

ABD GVT Revisions F and G should be 

considered equivalent for the purpose of 

AEB testing covering the current NCAP 

test scenarios. DENSO and Honda 

(which expressed a preference for ABD 

GVT Revision G) mentioned that since 

the rear components of both ABD GVT 

Revisions F and G have ‘‘equivalent 

physical characteristics,’’ they would be 

expected to perform the same in 

scenarios simulating rear-end crashes. 

However, a few of the commenters who 

supported adopting ‘‘lower’’ ABD GVT 

revisions for the proposed AEB test 

matrix, including Auto Innovators and 

GM, remarked that they would 

recommend use of only ‘‘higher’’ ABD 

GVT revisions (e.g., ABD GVT Revision 

G and newer) in the future to improve 

correlation if additional test conditions 

with different approach angles and/or 

directions are added to Agency testing. 

Some commenters, such as GM, 

supported adoption of ABD GVT 

Revision E in addition to ABD GVT 

Revisions F and G. Auto Innovators and 

HATCI preferred ABD GVT Revision G 

but additionally supported the inclusion 

of both ABD GVT Revisions E and F for 

use in current NHTSA NCAP test 

conditions. HATCI suggested that the 

Agency allow use of ABD GVT 

Revisions E and F in case of damage or 

supply shortages. CAS did not agree that 

the Agency should accept data from 

tests utilizing ABD GVT Revision E if 

that version is ‘‘obsolete’’ and ABD GVT 

Revisions F and G are now available. 

Regarding the timeline and 

preparation for inclusion, HATCI 

requested that manufacturers be given a 

two-year lead-time to align with product 

development cycles if the Agency was 

to adopt an alternative GVT revision in 

the future. Auto Innovators requested 

that NHTSA work with other NCAPs to 

harmonize development of future 

versions of a global vehicle test device 

suitable for testing. 

Response to Comments and Agency 

Decisions 

Use of the ABD GVT Revision G in Lieu 

of the SSV 

Commenters overwhelmingly 

supported replacing the SSV with the 

ABD GVT Revision G in NCAP testing, 

with many echoing points expressed by 

NHTSA in its March 2022 RFC notice. 

Most notably, commenters stated that 

adoption of the ABD GVT Revision G 

permits harmonization with other 

consumer information programs, 

including Euro NCAP, and allows the 

Agency to incorporate higher speed tests 

and additional test scenarios, including 

those for other ADAS technologies. The 

ABD GVT Revision G is an appropriate 

surrogate for use in NCAP testing given 

its physical characteristics, material 

properties, and durability, especially 

when compared to the SSV. The vehicle 

test device complies with ISO/AWI 

19206–3:2021, ‘‘Road vehicles—Test 

devices for target vehicles, vulnerable 

road users and other objects, for 

assessment of active safety functions— 

Part 3: Requirements for passenger 

vehicle 3D targets’’ 150 with respect to 

the specifications outlined for radar 

cross section, reflectivity, color, and 

physical dimensions. As such, it is 

considered to be representative of a real 

vehicle. Further, in the Agency’s most 

recent high-speed AEB research tests, 

the ABD GVT Revision G was found 

capable of operation at higher speeds 

and durable enough to receive impacts 

at higher relative speed than possible 

with the SSV. Accordingly, NHTSA 

plans to use the ABD GVT Revision G 

to conduct NCAP testing to measure the 

performance of AEB systems beginning 

with model year 2026 vehicles. 

Although the Agency did not specify 

in its RFC notice a specific robotic 

platform to be used with the GVT, a few 

commenters recommended that NHTSA 

harmonize its platform(s) with Euro 

NCAP’s to decrease burden. Because the 

GVT’s movement will be subjected to 

specifications (speed, deceleration 

magnitude, etc.), the Agency does not 

see a substantial need to specify which 

platform must be used to achieve the 

appropriate POV kinematics. 

Consideration of Other ABD GVT 

Revisions and Alternative GVTs 

The Agency notes that several 

commenters favored adoption of ABD 

GVT Revision E and/or F in addition to 

Revision G, or desired a phase-in period 

for adoption of ABD GVT Revision G. 

Since ABD GVT Revision G only 

includes changes to the front and sides 

of Revision F, it is reasonable to 

continue to accept data using ABD GVT 

Revision F for LVS, LVD, and LVM AEB 

test scenarios for a period of time. 

NHTSA will accept manufacturers’ AEB 

self-reported data for tests that use 

either ABD GVT Revisions F or G for the 

first two model years under the new 

ADAS testing program (i.e., for model 

year 2026 and model year 2027). For 

model year 2028 and beyond, the 

Agency will only accept AEB data 

generated using the ABD GVT Revision 

G vehicle test device. This two-year 

period allows sufficient lead-time for 

vehicle manufacturers to procure the 

required GVT and complete testing for 

model year 2028 models. Since the 

Agency is making extensive changes to 

the AEB test procedures, including 

integrating FCW evaluations (as will be 

discussed in a later section), no test data 

collected for model year 2025 vehicles 

will carry over to model year 2026. 

Therefore, it is expected that vehicle 

manufacturers will have to conduct the 

updated AEB tests for all vehicle models 

in their model year 2026 fleet to claim 

AEB NCAP credit. Although the Agency 

anticipates that most manufacturers will 

utilize ABD GVT Revision G during 

testing conducted for their model year 

2026 models, the Agency recognizes 

that manufacturers may experience 

procurement delays when obtaining 

ABD GVT Revision G such that only the 

Revision F version of the test device 

may be available for testing. Therefore, 

providing a short lead-time to account 

for this possibility is appropriate. For its 

own testing, NHTSA will utilize ABD 

GVT Revision G to validate AEB system 

performance beginning with model year 

2026 vehicles. 

NHTSA has decided it will not accept 

data obtained from tests utilizing ABD 

GVT Revision E for the 2026 model year 

and beyond. The Agency agrees with 

CAS that this version should be 

considered ‘‘obsolete’’ since it is no 

longer in production. Further, data 

gathered from testing conducted with 

the SSV will also not be eligible for 

credit starting in model year 2026. As 


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151The TTCs prescribed for actuator braking in 

NCAP’s DBS test procedure are 1.1 seconds, 1.0 

second, and 1.4 seconds, respectively, for the LVS, 

LVM, and LVD scenarios. 

152European New Car Assessment Programme 

(Euro NCAP) (November 2022), Test Protocol—AEB 

Car-to-Car systems, Version 4.1.1. See Annex A. 

153Fitch, G.M., Blanco, M., Morgan, J.F., Rice, 

J.C., Wharton, A., Wierwille, W.W., & Hanowski, 

R.J. (2010, April) Human Performance Evaluation of 

Light Vehicle Brake Assist Systems: Final Report 

(Report No. DOT HS 811 251) Washington, DC: 

National Highway Traffic Safety Administration, p. 

101. 

mentioned in the March 2022 RFC 

notice, NHTSA plans to only accept 

self-reported manufacturer data from 

tests conducted in accordance with its 

test procedures to uphold NCAP’s 

credibility. This requirement includes 

use of the prescribed test device, when 

applicable. Vehicles failing to provide 

passing performance during the 

Agency’s assessments will not receive 

credit for AEB technology, regardless of 

whether passing results were provided 

by the vehicle manufacturer in response 

to NCAP’s annual data information 

request. 

Although nearly all commenters 

supported adoption of Revision G of the 

ABD GVT, the Agency recognizes that 

Bosch recommended NHTSA 

incorporate by reference ISO/AWI 

19206–3:2021 in NCAP, rather than 

stipulate a specific vehicle test device 

for use in the program’s AEB tests. The 

Agency has not conducted thorough 

evaluations of alternative test devices, 

such as the 4a GVT, to ensure they 

invoke equivalent vehicle/system 

performance as the ABD GVT Revision 

G in the Agency’s AEB tests. Therefore, 

at this time, the Agency is specifying 

use of the ABD GVT Revision G in the 

NCAP AEB tests to mitigate variability 

between the Agency’s test results and 

those submitted by the manufacturer. As 

noted earlier, the ABD GVT Revision G 

meets the ISO 19206–3:2021 

specifications. 

Vehicle Test Device Specifications 

Since AEB systems currently on the 

market may utilize camera-, radar-, and/ 

or lidar-based sensors (or some 

combination thereof) to provide 

automatic emergency braking, the 

vehicle test device adopted for NCAP’s 

AEB testing must meet certain 

specifications to ensure the SV 

recognizes the target as a real-world 

vehicle to ensure real-world benefit and 

assure test repeatability and 

reproducibility. These specifications 

include (1) physical dimensions, such 

as vehicle width; (2) features that are 

identifiable on the rear of a typical 

passenger vehicle, such as tail lamps, 

reflex reflectors, windows, and the rear 

license plate; (3) those addressing visual 

and near infrared specifications, such as 

for the exterior of the vehicle and also 

for various surface features, including 

tires, windows, and reflex reflectors; 

and (4) radar reflectivity, since many 

AEB systems rely on radar sensors in 

some capacity to identify the presence 

of other vehicles. Specifications for 

acceptable vehicle test devices are 

defined in ISO 19206–3:2021, and as 

mentioned, ABD states that the GVT 

Revision G meets these requirements as 

manufactured. Given this, it is 

unnecessary to prescribe additional 

specifications for the ABD GVT 

Revision G for NCAP testing, as 

compliance with the ISO standard in its 

entirety should be inherent. That said, 

the Agency will reference ISO 19206– 

3:2021 in NCAP’s AEB test procedures 

to ensure any device utilized for Agency 

testing complies with the standard’s 

specifications. 

h. DBS Brake Application Timing 

The Agency proposed that, should it 

decide to continue to perform DBS 

testing in NCAP, in lieu of the current 

procedure of initiating manual braking 

at prescribed TTCs for each test 

scenario,151 brake application for all 

LVD, LVS, and LVM DBS test scenario 

and speed combinations would occur at 

a time corresponding to 1.0 second after 

the FCW is issued. NHTSA proposed 

this change would apply regardless of 

whether automatic braking occurs after 

the FCW but before initiation of the 

manual brake application. The Agency 

reasoned this procedural modification 

would better represent real-world use 

and driving conditions while also being 

in basic agreement with the approach 

specified for FCW performance 

evaluations in Euro NCAP’s AEB Car-toCar systems test protocol.152 Euro NCAP 

requires that brake application begin 1.2 

seconds after issuance of the FCW. As 

an alternative to this proposal, NHTSA 

also requested comment on appropriate 

TTCs for the modified test conditions. 

Summary of Comments 

Many commenters, including Toyota, 

Honda, GM, and Tesla, agreed with the 

Agency’s proposal to trigger manual 

brake application 1.0 second after the 

FCW is issued in DBS testing. GM 

supported the proposed changes for the 

Agency’s DBS test procedure, stating 

that such modifications would better 

align with protocols used by other 

NCAPs and ‘‘provide a more 

comprehensive assessment of overall 

system performance.’’ GM, Honda, and 

ZF Group commented that the proposed 

time of 1.0 second after issuance of an 

FCW would reasonably simulate the 

time it might take a driver to depress the 

vehicle’s brake after an FCW is issued. 

Tesla agreed that this was a reasonable 

method of replicating human behavior 

but cautioned the Agency to use factory 

default settings for configurable FCW 

timing settings to ensure consistency 

across vehicle models. 

Auto Innovators, Bosch, IDIADA, and 

Intel agreed with the Agency’s proposal 

of applying the brake 1.0 second after 

the FCW was issued in DBS tests but 

suggested that a brake application 

timing of 1.2 seconds after the FCW, as 

used by Euro NCAP, would also be 

reasonable. Like other commenters, 

Auto Innovators stated that triggering a 

brake application at a prescribed time 

after issuance of an FCW in the 

Agency’s DBS tests rather than at a fixed 

TTC is more appropriate since the intent 

of an FCW is to compel the driver to 

react; thus, it should be more 

representative of the driver’s behavior 

under real-world conditions. The group 

added that aligning with Euro NCAP’s 

brake activation timing would reduce 

test burden. 

Rivian stated the Agency should 

adopt a ‘‘lower time gap’’ between the 

FCW and manual brake application 

because CIB will often activate and 

move the brake pedal before DBS 

activation, (as the Agency 

acknowledged in its 2022 RFC notice), 

such that not all DBS systems may be 

effectively assessed if the Agency were 

to adopt the proposed test procedure 

modifications. Similarly, in agreement 

with its recommendation to conduct 

integrated assessments for FCW, CIB, 

and DBS collectively ‘‘to better assess 

the total safety benefit,’’ BMW stated 

that once CIB activates, ‘‘any DBS 

influence is irrelevant.’’ 

CAS recommended that the Agency 

should base brake application timing for 

DBS testing on actual human driver 

responses to an FCW. 

Response to Comments and Agency 

Decisions 

To provide a comprehensive 

assessment of AEB system performance, 

the Agency has decided to initiate 

manual (robotic) brake application in 

NCAP’s LVS, LVD, and LVM DBS tests 

at a time that corresponds to 1.0 ± 0.1 

seconds after issuance of the required 

FCW signals (i.e., both signals for any 

bimodal warning, as will be discussed 

later) instead of at prescribed TTCs, as 

is done currently. The prescribed 1.0- 

second delay is based on the time it 

takes a driver to react when presented 

with an obstacle.153 If the FCW (i.e., one 

or more of the required two signals) is 

not issued in an LVS, LVD, or LVM DBS 


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154 In this instance, the vehicle will also fail the 

trial run. 155For the false positive DBS tests, the subject 

vehicle accelerator pedal will be released at any 

rate, such that it is fully released within 500 

milliseconds, either when a forward collision 

warning is given or at a headway that corresponds 

to a time-to-collision of 2.1 seconds, whichever 

occurs earlier. 156Fitch, G.M., Blanco, M., Morgan, J.F., Rice, 

J.C., Wharton, A., Wierwille, W.W., & Hanowski, 

R.J. (2010, April) Human Performance Evaluation of 

Light Vehicle Brake Assist Systems: Final Report 

(Report No. DOT HS 811 251) Washington, DC: 

National Highway Traffic Safety Administration, p. 

101. 

157Forkenbrock, G.J., & Snyder, A.S. (2015, June), 

NHTSA’s 2014 automatic emergency braking test 

track evaluations (Report No. DOT HS 812 166), 

Washington, DC: National Highway Traffic Safety 

Administration. 

test, the SV accelerator pedal will not be 

released, and the brake will not be 

manually applied prior to impact with 

the vehicle test device (i.e., POV).154

This planned procedural change will 

not apply to the false positive DBS 

assessment since an FCW is not 

expected during this assessment (though 

it may occur). For the false positive DBS 

test, the SV brakes will be applied (after 

throttle release) 155 at a TTC of 1.1 

seconds, corresponding to a nominal 

distance of 24.4 m (80.2 ft.) from the 

edge of the STP. 

NHTSA notes that commenters were 

generally supportive of this proposed 

change and agreed that such an 

approach better represents human 

behavior during real-world driving. 

Several respondents also noted this 

approach aligns well with Euro NCAP’s 

AEB Car-to-Car systems test protocol, 

which specifies that braking is applied 

1.2 seconds after the FCW is issued. 

Though some commenters requested 

that the Agency harmonize precisely 

with Euro NCAP’s specification, the 

Agency’s requirement is reasonable, and 

NHTSA has no data showing that a 

reaction time of 1.2 seconds is more 

appropriate. Previous NHTSA research 

has shown it takes drivers 1.04 seconds, 

on average, to begin applying the brake 

when presented with an unexpected 

obstacle, and 0.8 seconds when 

presented with an anticipated 

obstacle.156 For similar reasons, NHTSA 

reasons it is inappropriate to adopt a 

lower time gap between the FCW and 

manual brake application, as requested 

by Rivian. 

Regarding Rivian’s concern that CIB 

may activate and move the brake pedal 

after the time of the FCW but before the 

brake pedal is manually applied one 

second later during DBS testing, the 

Agency has observed this phenomenon 

and does not consider it problematic for 

several reasons. First, although the 

presence of CIB braking may negate the 

need for DBS activation (i.e., the 

supplemental braking typically 

associated with DBS is not required 

since the CIB system may already be 

braking the vehicle at its maximum 

capability), the manual brake 

application timing relative to the FCW 

is not changed and the crash avoidance 

performance requirement remains in 

place, so the test severity is fully 

retained. Second, tests where the brakes 

are manually applied after a CIB 

intervention has been initiated provide 

an opportunity not only to demonstrate 

the vehicle can avoid the POV, but also 

to ensure that the driver’s input does 

not override the CIB system such that it 

reverts to the braking level input by the 

driver alone (i.e., without any braking 

contribution from AEB), since doing so 

would be expected to result in contact 

with the POV, and therefore a test 

failure. Third, the Agency defines the 

onset of SV manual brake application as 

when the force applied to the brake 

pedal is ≥11 N (2.5 lbf), not when the 

brake pedal physically moves. This is a 

consideration for both CIB and DBS 

tests when assessing whether a given 

test trial is valid (i.e., performed 

properly). For CIB testing, the Agency’s 

test procedure prohibits the driver from 

applying force to the brake pedal during 

the test’s validity period. For DBS 

testing, the onset of SV manual braking 

is important when assessing manual 

brake application timing relative to the 

onset of the FCW. 

Given the Agency’s decision to 

initiate manual (robotic) brake 

application in NCAP’s LVD, LVS, and 

LVM DBS tests at a time that 

corresponds to 1.0 ± 0.1 seconds after 

issuance of the required FCW signals, 

the Agency has also tried to limit the 

effect of different FCW timing settings 

(e.g., early vs. late) on AEB testing 

outcomes to best ensure consistency 

across vehicle models, as Tesla 

suggested. As discussed later in this 

final notice, NHTSA has decided to 

specify use of the middle (or next latest) 

FCW setting in lieu of the default setting 

(as Tesla requested) or the latest alert 

setting for NCAP testing. This is because 

the warning setting most preferred by 

drivers will likely correspond to the 

default setting and should generally fall 

in the middle of the range of driver 

setting preferences that span either 

earlier or later alert settings. 

i. SV Throttle and Brake Application 

Overlap in DBS Tests 

The Agency’s existing DBS test 

procedure states that the accelerator 

pedal must be fully released within 500 

ms after an FCW is issued but prior to 

the onset of the manual SV brake 

application by a robotic brake 

controller, a timing currently dictated in 

the test procedure (as prescribed TTCs) 

for each test condition. As mentioned 

previously, if the Agency decided to 

continue to perform DBS testing in 

NCAP, it proposed to revise the time 

when the manual (robotic) brake 

application is initiated during testing to 

a time that corresponds to 1.0 second 

after the FCW is issued, even in 

instances where automatic braking (i.e., 

CIB) occurs after the FCW but before 

initiation of the manual brake 

application. However, as an alternative 

to this proposed procedural change, 

NHTSA also requested comment on 

appropriate revised TTCs for the 

modified DBS test conditions. In the 

event the Agency decided to proceed 

with this alternative proposal to adopt 

revised TTCs, NHTSA proposed that the 

current test specifications for pedal 

release timing (i.e., within 500 ms after 

an FCW is issued, but prior to the onset 

of the prescribed manual SV brake 

application by a robotic brake 

controller) would be maintained. 

In its March 2022 RFC notice, the 

Agency recognized that the current test 

requirements for pedal release timing 

can be problematic if no FCW is issued 

or if the alert happens very close to the 

prescribed brake activation timing, 

because the throttle may still be 

depressed (since no warning was issued, 

or it was issued late) while the SV 

brakes are applied by the robot at the 

prescribed TTC. The Agency 

documented this possibility (i.e., where 

the SV throttle and brake pedals are 

applied at the same time) during track 

testing and provided a recommendation 

that up to a 250 ms overlap be 

allowed.157 In other words, once the SV 

driver detects that the robot has applied 

the brakes, the driver will have 250 ms 

(instead of 500 ms) to fully release the 

accelerator. A test run would not be 

valid unless this criterion is met. 

Given the Agency’s findings and 

recommendation, NHTSA sought 

comment on whether it would be 

acceptable to modify NCAP’s DBS test 

procedure (in the event it adopted 

revised TTCs for the modified DBS test 

conditions) to allow a 250 ms overlap of 

SV throttle and brake pedal application 

in instances where no FCW has been 

issued by the prescribed TTC in a DBS 

test, or where the FCW is issued very 

close to brake activation. 

Summary of Comments 

Several commenters, including Auto 

Innovators, FCA, GM, and Rivian, stated 

that a 250 ms overlap for SV throttle and 

brake pedal application was acceptable. 

Rivian added that it appropriately 


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158National Highway Traffic Safety 

Administration (2015, October), Dynamic brake 

support performance evaluation confirmation test 

for the New Car Assessment Program, http://

www.regulations.gov, Docket No. NHTSA–2015– 

0006–0026. 

159Regenerative braking slows a vehicle down 

when the accelerator pedal is released, which helps 

traditional brakes. It also recovers kinetic energy 

that would otherwise turn into heat by converting 

it into electrical energy for storage in onboard 

propulsion batteries. Regenerative braking is a 

common feature in electric-powered vehicles. 

160For instance, if the regenerative braking from 

simply releasing the accelerator pedal results in 

0.3g braking, the additional braking required from 

the actuator to achieve a total deceleration of 0.4g 

would be a very low force and/or brake pedal 

displacement. 

simulates panic braking within 250 ms 

of an FCW in real-world driving 

situations. Honda also agreed that such 

an overlap was unobjectionable ‘‘as long 

as the application of SV throttle is not 

excessive’’ since this could possibly 

affect braking performance. 

In contrast, IDIADA and Intel did not 

support any amount of throttle and 

brake overlap. IDIADA commented that 

the DBS test procedure is intended to 

simulate a driver’s normal response in 

situations represented by the test 

scenarios. As such, the laboratory 

asserted there should be no overlap 

between brake and throttle application 

since the driver would normally be 

operating both pedals with one foot, and 

therefore could not depress both 

simultaneously. Intel expressed a 

similar sentiment. 

TRC noted that, as not all throttle 

robots permit application of both the 

brake and throttle at once, some test 

entities may have to purchase new 

equipment if NHTSA was to adopt this 

test procedural change. 

Response to Comments and Agency 

Decisions 

NHTSA has decided not to adopt a 

250 ms overlap for testing scenarios, 

despite several commenters stating that 

such an overlap is acceptable. The 250 

ms overlap is unnecessary because it 

has implemented requirements in 

NCAP’s LVD, LVS, and LVM DBS tests 

to (1) fully release the SV’s accelerator 

pedal (at any rate) within 500 ms after 

an FCW is issued (whether it be before 

or after automatic braking has begun), 

and (2) initiate manual (robotic) brake 

application at a time that corresponds to 

1.0 ± 0.1 seconds after issuance of the 

required FCW signals (i.e., any dualmodality alert, as discussed later) 

instead of at currently prescribed TTCs. 

In any situation, the throttle should be 

fully released for a minimum of 500 ms 

prior to manual brake application. This 

manual (robotic) braking procedure 

aligns with comments received from 

IDIADA and Intel, both of which stated 

it was inappropriate for throttle 

depression to overlap with brake 

application. The Agency agrees with 

IDIADA that NCAP’s DBS test procedure 

should simulate real-world driving 

conditions, where the driver’s foot 

would be removed from the throttle 

prior to depressing the brake. The 

changes NHTSA has made to throttle 

release and robotic brake application 

timing requirements reflect that 

intention. 

NHTSA also asserts the possibility of 

SV throttle and brake application 

overlap does not exist for the false 

positive DBS assessment. In the false 

positive DBS test, issuance of an FCW 

is not expected (though it may occur). 

As such, the SV throttle is to be released 

within 500 ms of the prescribed TTC 

(2.1 seconds) if no FCW is issued by the 

specified time. If an FCW is issued, the 

SV throttle is released within 500 ms of 

the warning. In both situations, the SV 

brakes are then to be applied at a TTC 

of 1.1 s, which corresponds to a nominal 

distance of 24.4 m (80.2 ft.) from the 

edge of the STP. Like the LVD, LVS, and 

LVM DBS tests, the SV accelerator 

should always be fully released for a 

minimum of 500 ms prior to brake 

application in the false positive DBS 

test, regardless of whether an FCW is 

issued. NHTSA notes that no 

commenters suggested revised TTCs for 

the false positive test condition. As 

such, the Agency will maintain the 

current TTC requirement for the 80 kph 

(49.7 mph) false positive test condition. 

This is reasonable given the same TTC 

requirements are currently specified for 

both the 40.2 kph (25 mph) and 72.4 

kph (45 mph) test speeds. 

Finally, TRC’s contention that some 

braking robots are not able to apply both 

the brake and accelerate at the same 

time is no longer a concern, because 

overlap between the SV throttle and 

manual brake application is now 

avoidable for all DBS tests due to the 

adopted throttle release and brake 

application timing requirements. 

j. Addition of Manual Brake Application 

Controller Option 

To achieve accurate, repeatable, and 

reproducible SV brake pedal inputs 

during NCAP’s DBS tests, NHTSA uses 

a programmable brake controller, set to 

one of two closed-loop control modes— 

constant pedal displacement or hybrid 

feedback—to command the necessary 

brake force.158

The Agency is incorporating a third 

manual brake application controller 

option, a force-only feedback controller, 

which will provide another useful 

method of brake application. The force 

feedback controller is substantially 

similar to the hybrid controller with the 

commanded brake pedal position 

omitted, leaving only the commanded 

brake pedal force application. 

For the force feedback procedure, the 

commanded brake pedal application is 

the brake pedal force that results in a 

mean deceleration of 0.4g in the absence 

of AEB system activation. The mean 

deceleration is the deceleration over the 

time from when the commanded brake 

pedal force is first achieved to 250 ms 

before the vehicle comes to a stop. The 

force controller applies a force of at least 

11.1 N (at an unrestricted rate) to the 

brake pedal to achieve the commanded 

brake pedal force within 250 ms. The 

force controller may overshoot the 

commanded force by any amount up to 

20 percent. If such an overshoot occurs, 

it must be corrected within 250 ms from 

when the commanded force is first 

achieved. The average pedal force must 

be maintained within 10 percent of the 

commanded brake pedal force from 250 

ms after the commanded pedal force 

occurs until test completion. 

k. Regenerative Braking 

In its March 2022 RFC notice, the 

Agency noted that regenerative 

braking 159 may influence vehicle 

performance during its AEB tests and 

create complications for DBS testing. 

Regenerative braking, which has 

become more common as electric 

vehicles have begun to proliferate the 

fleet, slows a vehicle when the 

accelerator pedal is released. As such, a 

vehicle that has regenerative braking 

may exhibit a significant speed 

reduction prior to the onset of AEBinduced braking during the Agency’s 

CIB and DBS testing, particularly in 

instances where the FCW is issued 

early, since the vehicle’s accelerator 

pedal is to be fully released upon the 

issuance of the FCW. Furthermore, a 

relatively high deceleration resulting 

from regenerative braking can introduce 

complications during DBS testing, as 

only a relatively small increase in 

braking from the braking actuator would 

be required to provide the necessary 

combined 0.4g deceleration.160

To limit the influence of regenerative 

braking during AEB testing, NHTSA 

proposed to select the ‘‘off’’ setting, or 

the setting that provides the lowest 

deceleration when the accelerator is 

fully released for those vehicles offering 

multiple regenerative braking settings 

(e.g., less aggressive, nominal, more 

aggressive). The Agency proposed to test 

with the least aggressive setting (or the 

‘‘off’’ setting) over the ‘‘nominal’’ setting 

for two reasons. First, NHTSA believed 


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161https://www.regulations.gov/comment/ 

NHTSA-2021-0002-3862. HATCI’s internal research 

covered nine focus groups of Hyundai and Kia 

vehicle owners from 2017–2019 from the Chicago, 

IL area (N=24) and an online survey. 

that the least aggressive (or ‘‘off’’) 

regenerative braking setting would be 

the setting most likely to produce 

comparable performance to vehicles that 

are not equipped with a regenerative 

braking feature. Second, the Agency 

reasoned that the least aggressive setting 

would likely afford ‘‘worst case’’ 

performance during testing, since it 

should generate the lowest deceleration 

and thus allow the vehicle to travel 

faster at the onset of AEB braking. The 

Agency did not propose to make any 

procedural modifications for vehicles 

that have regenerative braking that 

cannot be switched off or adjusted, 

since those vehicles should operate 

similarly during testing as compared to 

real-world driving. 

Comments were requested on whether 

the proposed setting selection was 

appropriate. NHTSA also requested 

comment on whether regenerative 

braking could introduce additional 

testing issues for the Agency’s AEB 

testing, such as those described, along 

with recommendations for test 

procedural changes to best address 

them. 

Summary of Comments 

Most commenters agreed with the 

Agency’s proposal to select the ‘‘off’’ 

setting during AEB NCAP testing. 

However, a few respondents favored the 

‘‘Default’’ setting or letting 

manufacturers choose the setting they 

preferred. 

Choose ‘‘Off’’ or the Lowest Setting 

Commenters who favored turning 

regenerative braking ‘‘off’’ and/or 

selecting the lowest regenerative braking 

setting for AEB testing included 

Advocates, BMW, CAS, FCA, GM, 

Honda, Intel, and TRC. Intel commented 

that choosing the regenerative braking 

setting that is considered ‘‘worst case’’ 

(i.e., ‘‘off’’) is ‘‘reasonable,’’ while CAS 

remarked that NHTSA should evaluate 

ADAS systems in ‘‘the least favorable 

foreseeable circumstances.’’ GM 

remarked that it was most appropriate to 

conduct a worst-case performance 

assessment for electric vehicles (i.e., 

regenerative braking ‘‘off’’) since it is 

currently unknown what percentage of 

drivers release the accelerator pedal 

prior to, or during, AEB activation (such 

that regenerative braking would engage). 

BMW asserted that selecting the ‘‘off’’ or 

lowest setting for regenerative braking is 

appropriate because choosing a setting 

that induces high regenerative braking 

may unfairly skew AEB test results. 

Advocates agreed that the regenerative 

braking setting should be set to ‘‘off’’ 

unless there is no way to disable it, and 

Honda commented that NHTSA’s 

approach seems ‘‘reasonable for most 

vehicles’’ for AEB and FCW 

assessments. 

A few commenters favored the ‘‘off’’ 

or lowest setting for regenerative 

braking because alternative settings may 

cause complications for testing. TRC 

and GM mentioned that the ‘‘off’’ or 

lowest settings simplify test execution. 

TRC added that they have seen 

instances where a test cannot be 

properly conducted per the applicable 

procedure to create a crash-imminent 

situation because of early FCWs coupled 

with high regenerative braking. FCA 

noted that disabling regenerative 

braking improves test repeatability, 

particularly for DBS tests, due to 

‘‘different brake pedal behavior when 

transitioning from regeneration to 

braking.’’ For this reason, the automaker 

recommended that the Agency select the 

‘‘off’’ setting in the near-term and switch 

to an alternative setting (resulting in a 

‘‘more complicated test’’) if real-world 

data supports this change. GM agreed 

that selecting the ‘‘off’’ setting for 

regenerative braking would lead to more 

consistent testing for electric vehicles. 

Choose the ‘‘Default’’ Setting 

In lieu of turning regenerative braking 

‘‘off’’ or to the lowest setting for AEB 

testing, Rivian, Tesla, and HATCI stated 

that NHTSA should use the factory 

default setting, as this setting is more 

consistent with real-world driving. 

HATCI commented that an internal 

study of Hyundai and Kia owners 

revealed that most owners do not 

change the ADAS settings from the 

factory default settings after purchasing 

a vehicle.161 As such, the commenter 

stated the Agency should only deviate 

from default settings for testing 

purposes if there is a need to do so to 

ensure safe test conduct. Given these 

findings for ADAS settings, HATCI 

encouraged NHTSA to conduct a similar 

fleet-wide study of customer-selected 

regenerative braking settings before 

incorporating related test procedure 

changes. Similarly, Tesla mentioned 

that the company’s fleet data has shown 

that over 80 percent of Tesla vehicles on 

the road use the default setting for 

regenerative braking. Like other 

commenters above, the manufacturer 

acknowledged that different 

regenerative braking settings will 

generate different AEB performance. 

Similar to TRC, Tesla mentioned that, 

depending on the regenerative braking 

setting selected, a vehicle may not even 

need to activate AEB in some test 

scenarios because regenerative braking 

effectively slows the vehicle to a stop 

and prevents it from making contact 

with the vehicle test device. 

Let Manufacturers Specify the Setting 

Auto Innovators explained that they 

were not opposed to turning 

regenerative braking ‘‘off’’ for electric 

vehicles but requested that NHTSA 

allow vehicle manufacturers to specify 

the regenerative braking setting they 

want to be tested (‘‘off’’ or otherwise) for 

each vehicle/test. 

Single-Pedal Operation Considerations 

Honda and Auto Innovators requested 

that NHTSA amend the AEB test 

procedures, where appropriate for 

electric vehicles, to clarify what it 

means for the throttle to be ‘‘fully 

released’’ in vehicles that use one pedal 

for both acceleration and braking. To 

accommodate vehicles using one pedal 

operation, the commenters suggested 

that ‘‘fully released’’ should translate to 

‘‘an accelerator position that provides 

deceleration equivalent to that of engine 

braking, about 0 to 0.1 g.’’ BMW 

expressed a similar sentiment. 

Response to Comments and Agency 

Decisions 

NHTSA has decided that, for NCAP’s 

AEB tests, it will adopt its initial 

proposal to select the ‘‘off’’ setting for 

regenerative braking, or the setting that 

provides the lowest deceleration when 

the accelerator is fully released for those 

vehicles offering multiple regenerative 

braking settings (e.g., less aggressive, 

nominal, more aggressive). Although 

some commenters shared the assertion 

that this setting is not reflective of realworld use, it is prudent to perform 

testing to represent the worst reasonable 

case scenario, a sentiment shared by 

multiple respondents. By taking such an 

approach, the vehicle’s speed just prior 

to either manual (robotic) or automatic 

braking will be retained to the greatest 

extent possible, which should allow the 

Agency to most objectively evaluate the 

vehicle’s ability to avoid a crash without 

introducing confounding factors caused 

by early FCWs or significant braking 

prior to the onset of AEB. In a similar 

vein, selecting the ‘‘off,’’ or least 

aggressive regenerative braking setting, 

should improve test execution, and thus 

test repeatability, and allow the Agency 

to evaluate actual system performance 

more effectively, as several commenters 

mentioned. Also, selecting the ‘‘off’’ 

setting promotes a level of fairness. This 

is particularly important for a consumer 

information program in which 

comparisons may be made between 


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162See Appendix A of Honda’s submission for 

detailed proposed revisions. 

vehicle model test results. If the Agency 

instead allowed vehicle manufacturers 

to specify any regenerative braking 

setting that they prefer, as Auto 

Innovators suggested, this could result 

in AEB performance that is not 

comparable to other tested vehicles in 

the fleet, and thus, not necessarily 

consistent in a way consumers might 

expect. 

With respect to accelerator pedal 

input and release for vehicles equipped 

with a one pedal operation mode, by 

setting regenerative braking to ‘‘off,’’ one 

pedal operation will also effectively be 

disabled in most instances. However, in 

agreement with the decision made 

above to select settings that provide the 

lowest deceleration in order to represent 

the worst reasonable case scenario, the 

Agency will also select the ‘‘off’’ setting 

for one pedal operation, for those 

vehicles offering selectable settings for 

modes of operation. If one pedal 

operation cannot be disabled (i.e., 

regenerative braking is always enabled 

and one pedal operation cannot be 

switched ‘‘off’’), the vehicle will be 

tested with the moderate deceleration 

level ensuing from accelerator pedal 

release. At this time, accelerator pedal 

release need not be defined beyond the 

definition applicable to vehicles that do 

not permit one pedal operation. The 

Agency will require the accelerator 

pedal to be fully released within 500 ms 

after the FCW is presented for all 

vehicles, including those equipped with 

a one pedal operation mode. 

For electric vehicles, propulsion 

batteries will be charged at 80 percent 

or higher capacity during NCAP’s AEB 

testing. This decision aligns well with 

the Agency’s decision to select the 

setting for regenerative braking that 

provides the lower deceleration when 

the accelerator is fully released. 

Performing AEB assessments with a 

higher SOC should limit regenerative 

braking. 

l. Refinement and Clarification of Test 

Procedures 

In addition to the changes discussed 

herein for NCAP’s AEB test procedures, 

the Agency also sought public comment 

on whether there are any aspects of 

NCAP’s current FCW, CIB, and/or DBS 

test procedure(s) that need further 

refinement or clarification. Commenters 

responded with recommendations for 

general test procedure clarifications, 

additions, and refinements. These 

recommendations tended to fall into 

three general categories: the use of 

robotic test equipment, tolerances 

currently used, and general test 

procedure changes to either increase the 

applicability of results or to increase 

repeatability. 

Summary of Comments 

Robotic Test Equipment 

Auto Innovators requested that driver 

braking be implemented in a ‘‘more 

realistic manner.’’ The group asserted 

that, in general, a brake robot ‘‘adds a 

degree of reliability to the test 

operation.’’ Accordingly, the 

organization suggested that the Agency 

eliminate human operation to the extent 

possible for all AEB tests and specify 

use of a robot-controlled POV test 

device. Toyota also asserted that the 

Agency should require the SV to be 

controlled by a steering robot controller 

since vehicle test devices can be 

controlled by a GST system. 

GM and Auto Innovators requested 

that NHTSA harmonize the robotic test 

equipment and settings used in NCAP’s 

tests with other equipment used by 

industry and other NCAPs globally. 

However, at a minimum, Auto 

Innovators requested NHTSA refine the 

brake robot procedure to add more 

detailed instructions about calibration 

and setup. Both commenters mentioned 

that one of NHTSA’s test contractors 

uses different robotic test equipment 

than that which is commonly used, and 

the robot parameters are applied slightly 

differently in NCAP’s tests. Per GM, 

troubleshooting performance issues may 

be difficult when differences arise 

because of various equipment and 

settings. 

TRC asked for NHTSA to clarify the 

meaning of the test procedure phrase 

‘‘smooth throttle inputs.’’ The 

commenter mentioned that data from 

brake and throttle robots, which are 

helpful to maintain speed tolerances, 

may appear ‘‘noisy’’ even with tuning. 

As such, they requested clarification on 

NHTSA’s definition of ‘‘smooth’’ in 

such instances. Auto Innovators 

requested that accelerator pedal release 

rates be defined in general. 

IDIADA noted that regenerative 

braking may affect the speed control 

during testing when regenerative 

braking is activated, such that the 

throttle robot may ‘‘over-throttle and 

result in an override action.’’ To prevent 

the occurrence of a system override, the 

commenter suggested that NHTSA 

‘‘ensure that [the] throttle robot is kept 

on [the] hold position prior to AEB 

activation.’’ 

Changes to Tolerances 

Honda and Auto Innovators asserted 

that the tolerances for POV and SV 

deceleration, POV and SV speed, and 

headways in the Agency’s CIB and DBS 

test procedures are currently too wide. 

The commenters noted the combined 

tolerance variation ‘‘have a significant 

influence on collision closing speed and 

timing,’’ and Honda added that certain 

tolerance combinations can prevent a 

possible SV and POV collision. As such, 

both commenters recommended that 

NHTSA adopt the tolerances Euro 

NCAP uses for these test variables to (as 

Honda stated) improve test objectivity 

and uphold program credibility.162

Toyota also recommended that NHTSA 

adopt Euro NCAP tolerances if the 

Agency ultimately decides to 

incorporate higher test speeds and 

higher decelerations for the lead vehicle 

with shorter headways. Toyota asserted 

that if test procedures allow for wide 

variation, then system design will need 

to cover the variation, potentially 

causing real-world false positive cases 

to increase. Intel suggested certain 

tolerances should be tightened, noting 

that if the headway and braking force of 

the braking robot are at the higher end 

of the tolerance range, ‘‘the brake robot 

itself is almost enough to avoid the 

collision,’’ making it difficult to assess 

what is supposed to be a crashimminent event. 

General Test Procedure Additions/ 

Clarifications 

To improve test repeatability and 

reproducibility, Tesla suggested NHTSA 

should better define the ‘‘end-of-theevent’’ in the test procedures. 

Additionally, CAS suggested that the 

Agency should conduct testing to 

ensure vehicles provide effective 

warnings when ‘‘safe operating limits 

are exceeded,’’ such as for certain 

environmental conditions (e.g., ice, 

snow), maximum speed conditions for 

ADAS operation, or upon violation of 

minimum following distances. 

Response to Comments and Agency 

Decisions 

Robotic Test Equipment 

Proper test conduct is vital to the 

credibility of NCAP, and the Agency 

seeks to maximize testing consistency 

wherever possible. NHTSA agrees with 

commenters that eliminating human 

operation as much as is practicable 

might be helpful in maintaining test 

repeatability. However, NCAP CIB and 

DBS testing currently utilizes a human 

driver to maintain SV lane position and 

speed, and NHTSA has not encountered 

problems with achieving valid tests 

using human inputs to satisfy the test 

tolerances associated with these 

parameters. Therefore, NHTSA is not 


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requiring robotic control of all SV 

inputs used to perform the Agency’s 

AEB tests. However, there are some 

inputs where robotic control is 

beneficial, namely those associated with 

the SV brake pedal inputs (e.g., force, 

velocity, and displacement) used during 

DBS testing. For instance, the test 

tolerances associated with these inputs 

must be accurately achieved and 

maintained throughout the brake 

application. Also, some vehicles require 

a precise transition from brake pedal 

inputs based on position control to 

those based on applied force. Such 

brake inputs are difficult to reproduce 

with a human driver. In the future, 

NHTSA may consider performing AEB 

tests using robotic control of all SV 

inputs. 

Along these lines, NHTSA will not 

harmonize the robotic test equipment 

and/or settings used with those used 

commonly in industry. The Agency has 

specified steering, throttle, and brake 

input requirements that must be met. 

Therefore, it is not warranted to specify 

particular equipment. 

With respect to the POV, the Agency’s 

decision to use the ABD GVT Revision 

G during NCAP’s AEB tests necessarily 

requires that the test device be secured 

to a robotic platform to facilitate 

movement during conduct of the LVM 

and LVD tests. For the sake of scenarioto-scenario consistency, the ABD GVT 

Revision G will also be secured to an 

LPRV during conduct of the LVS tests. 

NHTSA notes that the movement of a 

robotic platform is accurately and 

repeatably controlled and can be safely 

achieved, monitored, and terminated, if 

necessary, by laboratory personnel at 

any time during a test trial. Given the 

demanding test conditions of the CIB 

and DBS tests described in this notice, 

these are all important considerations. 

NHTSA received general comments 

regarding throttle and brake inputs. 

Pertaining to the test procedure phrase 

‘‘smooth throttle inputs,’’ there is no 

current definition of this phrase. The 

intent underlying this description is that 

the manner in which the accelerator 

pedal inputs are applied must not 

confound AEB operation or affect the 

test outcome. As described in the 

previous section, further definition of 

accelerator pedal release rates, as Auto 

Innovators requested, is unnecessary. 

Finally, NHTSA has not encountered 

the over-throttling problem that IDIADA 

has described; therefore, no changes 

will be made to the test procedure at 

this time to alter throttle robot inputs. 

However, the Agency will make 

refinements to the procedures in the 

future to clarify additional details if the 

need arises. 

Changes to Tolerances 

NHTSA acknowledges that several 

commenters to the March 2022 RFC 

notice reasoned that many tolerances in 

the Agency’s CIB and DBS test 

procedures should be revised. 

Specifically, commenters remarked that 

tolerances were too wide. Honda noted 

that wide tolerances in NHTSA’s DBS 

LVD test procedure may compound and 

allow for a vehicle with borderline 

performance to either make contact or 

not, depending on test parameters. 

NHTSA does not expect Honda’s 

concern to be relevant for the updated 

NCAP AEB tests. Specifically, the wide 

assortment of test conditions being 

evaluated (e.g., POV speed 

combinations, SV-to-POV headways and 

POV decelerations (for LVD tests)), 

along with a no-contact criterion, 

contributes to greater test stringency 

overall. A vehicle achieving marginal 

performance will likely have difficulty 

passing the suite of tests performed by 

NCAP. Further, the Agency’s current 

test tolerances balance the desire to 

perform the tests as accurately and 

consistently as possible with the ability 

to practically perform them. NHTSA has 

demonstrated the practicability of using 

its AEB test tolerances during NCAP 

and research testing; thus, it is 

appropriate to retain their use during 

conduct of the updated NCAP CIB and 

DBS tests. 

Regarding comments on SV speed, 

NHTSA’s experience is that test vehicle 

speed can be reliably controlled within 

the proposed tolerance, and that speed 

variation within the tolerance yields 

consistent results. A smaller speed 

tolerance would be unnecessarily 

burdensome, as it may result in a higher 

rate of invalid test runs without any 

greater assurance of test accuracy. 

Therefore, the Agency will proceed with 

a speed tolerance of ±1.6 kph (±1.0 mph) 

for both the SV as well as for the POV 

in NCAP’s CIB and DBS testing. 

General Test Procedure Additions/ 

Clarifications 

Regarding comments relating to the 

definition of the end of the validity or 

test period, for the AEB LVS and LVD 

scenarios, NHTSA considers a test run 

complete when either of the following 

occurs: (1) the SV contacts the POV; or 

(2) the SV comes to a complete stop 

without making contact with the POV. 

For the AEB LVM test scenario, a test 

run is considered complete when either 

of the following occurs: (1) the SV 

contacts the POV; or (2) the SV speed 

becomes less than or equal to the POV 

speed without contacting the POV. For 

the false positive STP test, the test is 

complete when either (1) the SV comes 

to a stop prior to crossing over the 

leading edge of the steel trench plate, or 

(2) when the frontmost part of the SV 

crosses over the leading edge of the STP. 

NHTSA acknowledges that some 

vehicles are equipped with telltales that 

alert the driver that an ADAS system is 

not functional. These cases may include 

manual system deactivation or detection 

of system malfunction, which may 

result from sensor obstruction or 

saturation due to accumulated snow or 

debris, sunlight glare, fog, and other 

environmental conditions. These 

warnings serve as an indication to the 

driver that assistance with the driving 

task is not available. While NHTSA 

agrees that these warnings are useful to 

the driver, stipulating the type, 

function, and performance of a system 

malfunction warning is out of scope of 

an NCAP evaluation and is more 

suitable for rulemaking. 

2. FCW 

a. NHTSA’s Proposal for FCW Testing, 

Including Alternatives 

NCAP’s current FCW requirements 

were developed at a time when FCW 

and AEB functionality were not 

integrated as part of one frontal crash 

prevention system. Consequently, when 

FCW was selected for inclusion in the 

program in 2008, the Agency adopted a 

test procedure and performance 

requirements that served only to 

evaluate the performance of FCW 

systems. However, in recent years, there 

has been a shift towards FCW and AEB 

system integration to improve realworld safety performance and consumer 

acceptance. It may be reasonable to 

combine FCW testing with AEB (and 

PAEB) testing such that FCW operation 

is evaluated as part of NCAP’s AEB (and 

PAEB) tests. NHTSA also expects this 

change would reduce test burden since 

there will not be an additional suite of 

tests to conduct solely for the purpose 

of verifying FCW performance. 

NHTSA’s Proposal for FCW Testing— 

Integrating FCW Assessments Into CIB 

Testing 

In its March 2022 RFC Notice, 

NHTSA proposed that the Agency’s CIB 

(and PAEB) tests could be used as an 

indicant of FCW functionality. 

Essentially, the Agency would evaluate 

the functionality of a vehicle’s FCW 

system during the CIB system 

evaluation by requiring the SV’s 

accelerator pedal to be fully released 

within 500 ms after the FCW is issued. 

If no FCW were issued during a CIB test, 

the SV accelerator pedal would be fully 

released within 500 ms after the onset 


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163The Agency proposed these test procedural 

changes for its PAEB tests as well. 

164To pass a test trial, the vehicle must issue the 

FCW on or prior to the prescribed time-to-collision 

(TTC) specified for each of the three FCW test 

scenarios. 

of CIB system braking (as defined in the 

Agency’s proposal as the instant SV 

deceleration reached at least 0.5g).163 If 

no FCW were issued and the vehicle’s 

CIB system did not offer any braking, 

release of the SV accelerator pedal 

would not be required prior to impact 

with the POV (i.e., the GVT). Comments 

were requested on whether this 

proposed approach was reasonable to 

assess FCW operation. 

NHTSA asserted that it was 

appropriate to assess the presence of an 

FCW within CIB (and PAEB) tests 

because the operation of FCW and AEB/ 

PAEB systems are complementary and 

fundamentally intertwined in the test 

scenarios currently assessed by NCAP. 

Therefore, it seemed appropriate to the 

Agency to begin to assess FCW timing 

relative to the intended onset of CIB 

activation instead of relative to an 

‘‘absolute TTC,’’ as in NCAP’s current 

FCW tests, since the former would be at 

the discretion of the vehicle 

manufacturer, which would have 

explicit knowledge of how the operation 

of their vehicles’ CIB systems affect the 

FCW TTC. The Agency proposed to 

integrate FCW performance assessments 

into its CIB tests rather than DBS tests 

because, as mentioned previously, the 

Agency had considered removing DBS 

testing from NCAP entirely, and 

alternatively, weighed performing DBS 

testing at only a limited number of 

higher speeds. As such, evaluating FCW 

functionality during DBS testing did not 

seem like a viable option at the time. 

Alternative 1—Conduct Multiple 

Separate FCW Assessments 

As an alternative to integrating FCW 

and CIB tests, NHTSA also mentioned 

that it could maintain the FCW test 

scenarios currently included in its FCW 

test procedure if commenters suggested 

the current testing approach was more 

appropriate than its consolidation 

proposal. If the Agency maintained 

separate FCW and CIB assessments, it 

proposed to align the corresponding 

maximum SV test speeds, POV speeds, 

headway, POV deceleration magnitude, 

etc., as applicable, for the FCW tests 

with the included CIB tests (which will 

be discussed later). More specifically, it 

proposed to adopt the following for 

NCAP’s FCW assessments: 

• LVS—SV speed of 80 kph (49.7 

mph); POV is stationary. 

• LVD—SV and POV speed of 50 kph 

(31.1 mph) or up to 80 kph (49.7 mph), 

depending on the final test speed 

adopted for the CIB LVD scenario; a 12 

m (39.4 ft.) SV-to-POV headway; and a 

POV deceleration magnitude of 0.5g. 

• LVM—SV speed of 80 kph (49.7 

mph); POV speed of 20 kph (12.4 mph). 

If the Agency continued to conduct 

separate FCW assessments that aligned 

procedurally with those required for 

CIB, NHTSA also reasoned it would be 

necessary to revise the prescribed TTCs 

currently used to assess FCW 

performance to reflect the revised test 

scenario and speed combinations.164 As 

such, NHTSA sought comment on what 

TTC would be appropriate for each test 

scenario. 

The Agency also proposed a revised 

assessment approach for FCW (in lieu of 

requiring a pass rate of at least five out 

of seven runs for each FCW test 

scenario, as is done currently) if FCW 

assessments were not integrated into 

those for CIB. The Agency proposed to 

conduct one test trial per test speed for 

each FCW test scenario and to increase 

test speeds in 10 kph (6.2 mph) 

increments from the minimum test 

speed to the maximum test speed. In the 

event of a test failure for instances 

where the SV has a relative velocity at 

impact that is equal to or less than 50 

percent of the initial SV speed, NHTSA 

proposed that up to four repeat trials 

would be performed. 

Alternative 2—Perform One Indicant 

FCW Assessment 

Given that most FCW systems are 

currently able to pass all relevant NCAP 

test scenarios, the Agency also 

suggested that as an alternative to 

retaining three separate FCW test 

scenarios (to be conducted per the test 

conditions prescribed for the related CIB 

tests), it may be feasible for NCAP to 

perform one FCW test (to be conducted 

per the test conditions prescribed for the 

comparable CIB test) that could serve as 

an indicant of FCW system 

performance. NHTSA reasoned that 

taking this approach for FCW testing 

would also reduce test burden, similar 

to its proposal to integrate FCW and CIB 

testing. For this alternative proposal, the 

Agency sought comment on which one 

of the proposed CIB test scenarios 

would be most appropriate to adopt for 

an FCW test to assess the performance 

of FCW systems. 

Assessment Method, Number of Trials, 

and Pass Rate (for Separate FCW 

Assessments) 

NHTSA also requested comment on 

whether an alternative assessment 

method would be appropriate if the 

decision was made to retain one or more 

FCW scenarios that would be performed 

at only a single test speed, such as for 

the LVS and LVM test conditions. In 

such instances, the Agency sought 

comment on whether it should require 

one trial per test condition (i.e., align 

with the assessment method proposed 

for the AEB test conditions) or conduct 

multiple trials instead, similar to the 

approach currently prescribed in 

NCAP’s FCW and AEB tests. If 

commenters preferred that the Agency 

adopt multiple trials in such instances, 

NHTSA asked how many trials would 

be appropriate, and what would be an 

acceptable pass rate. 

The changes NHTSA proposed for its 

FCW test procedure as well as possible 

alternatives are shown in Table 16. 

TABLE 16—FCW TEST SCENARIOS AND CONDITIONS—PROPOSALS AND ALTERNATIVES

Test 

scenario 

SV Speed 

(kph (mph)) 

POV Speed 

(kph (mph)) 

POV Headway 

(m (ft.)) 

POV 

deceleration (g) 

Proposal ................................................. Evaluate FCW during all CIB testing (release throttle within 500 ms after FCW). 

Alternative 1 ........................................... LVS .............................. 80 (49.7) 0 n/a n/a 

LVM ............................. 80 (49.7) 20 (12.4) n/a n/a 

LVD * ............................ 80 (49.7) 80 (49.7) 12 (39.4) 0.5 

Alternative 2 ........................................... Evaluate FCW in one CIB test condition only. 

* For LVD, NHTSA proposed adoption of the highest CIB SV/POV speed for the FCW assessment. 


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165Also see Auto Innovators Appendix 1. 166See GM Attached A and Table 1. 

Summary of Comments 

Integrating FCW Assessments Into CIB 

Testing 

The majority of commenters (BMW, 

MEMA, DENSO, GM, HATCI, Intel, 

Auto Innovators, Rivian, and TRC) 

supported the consolidation of FCW and 

CIB tests into a single evaluation. Rivian 

expressed that combining FCW and CIB 

is appropriate because FCW and AEB 

rely on the same inputs, and FCW is 

designed to work in a sequential manner 

with AEB. The automaker also 

mentioned that consolidation of FCW 

and AEB testing would reduce overall 

test burden, an assertion also expressed 

by Auto Innovators, GM, and TRC. 

Additionally, TRC mentioned that 

combining assessments for FCW and 

CIB functionality seemed logical since 

the timing of FCWs is already collected 

during the Agency’s CIB tests. IDIADA 

also articulated this assertion. 

DENSO also noted that it was 

appropriate to integrate FCW and CIB 

testing since voluntary agreements have 

helped to standardize CIB. The 

company asserted that this was even 

more fitting if the Agency was 

considering higher-speed CIB 

assessments, since Euro NCAP’s AEB 

Car-to-Car test protocol stipulates 

assessment of FCW functionality within 

the CIB assessments at even higher 

speeds than those utilized to evaluate 

CIB functionality. NTSB supported 

harmonizing NHTSA’s FCW test 

protocol with those used by other 

NCAPs, and consolidating FCW and 

AEB testing, but expressed concern that 

the proposed maximum SV test speed of 

80 kph (49.7 mph) is inadequate, as it 

is only slightly higher than the SV speed 

currently specified in NCAP’s FCW test 

procedure (72.4 kph (45 mph)). 

Bosch also supported harmonization 

with Euro NCAP, suggesting that 

NHTSA combine assessments for FCW, 

CIB, and DBS, as they maintained it 

would be difficult to define acceptable 

TTCs for FCW alone. Thus, instead of 

specifying prescribed TTCs for FCW, 

Bosch favored stipulating when FCWs 

should be issued prior to AEB braking. 

Like Bosch, BMW and Auto Innovators 

stated consolidation of FCW, CIB, and 

DBS testing was appropriate, since all 

three systems are designed to work 

together to achieve the same goal of 

rear-end crash avoidance or crash 

mitigation through speed reduction.165

The commenters recommended that the 

Agency combine FCW, CIB, and DBS 

assessments into one test series 

consisting of multiple test scenarios 

since this would better assess the safety 

rendered by the systems collectively 

and align with other NCAPs globally. 

They also noted that FCW system 

requirements were determined at a time 

when FCW and AEB functionalities 

were not necessarily integrated with one 

another, as they often are currently. GM 

also supported consolidating FCW and 

CIB/DBS testing like that employed in 

test protocols used in other global 

NCAPs. The automaker expressed that 

FCW should be assessed as part of the 

overall system performance since AEB 

systems are now widely available in 

current vehicles and provide additional 

safety benefits compared to FCWs 

alone.166

Both GM and Auto Innovators 

mentioned two potential ways the 

Agency could integrate FCW 

performance assessments into AEB tests, 

with both affording an overall 

assessment of system performance. The 

commenters stated the Agency could 

trigger activation of the brake robot 

during DBS testing based on the timing 

of the FCW, as is done by Euro NCAP. 

Alternatively, they stated NHTSA could 

directly assess FCW timing during CIB 

tests if the Agency’s FCW and CIB 

protocols included the same test 

conditions, as is the case currently for 

the LVM 45_20 condition. The 

commenters expressed that appropriate 

FCW TTCs for the other CIB scenarios/ 

conditions could be similarly calculated 

using the same approach NHTSA used 

to establish criteria for the LVM 45_20 

condition. Although the respondents 

suggested the latter option may provide 

a simpler test method, they preferred 

that the Agency adopt the methodology 

employed by Euro NCAP, stating that 

this method would also provide the best 

indication of appropriate timing for 

brake pedal application. The 

commenters favored combining FCW 

and CIB assessments over NCAP’s 

current evaluation method, which 

stipulates separate assessments for each 

technology. This is because the 

commenters supported evaluations for 

the same test scenarios but over a 

varying range of speeds. If the Agency 

ultimately chose not to combine FCW 

and AEB assessments, Auto Innovators 

suggested that it should continue to 

conduct all three of the current FCW 

test scenarios. 

Advocates stated they supported 

consolidating FCW and CIB testing if 

NHTSA provided data and analysis to 

support such a decision, and if the 

Agency was able to ensure the adopted 

test procedure could adequately assess 

the functionality for each system 

independently. 

A few commenters, including Honda, 

Toyota, FCA, and CAS, did not support 

consolidating FCW and CIB testing. 

Honda stated that it was more 

appropriate to instead consolidate FCW 

and DBS tests, since the two 

technologies are designed to work in 

tandem to mitigate or avoid a rear-end 

collision (i.e., the driver is aware of the 

impending collision and responds to the 

FCW by braking), and CIB is designed 

to operate alone (i.e., the driver is not 

aware of the impending threat and 

therefore does not apply the vehicle’s 

brakes in response to an FCW, and as 

such, is also unlikely to have released 

the accelerator pedal). FCA and Toyota 

also supported consolidating FCW and 

DBS testing for similar reasons. FCA 

stated that CIB can be executed 

differently when the attentiveness of the 

driver is present, and that automatic 

braking from CIB is more effective at 

low speeds than manual braking 

resulting from the combination of FCW 

and DBS, such that FCW would not 

necessarily be issued in such situations. 

Toyota also supported combined FCW 

and DBS testing because such an 

approach would be like that used by 

Euro NCAP. Furthermore, in the case of 

combined FCW and CIB testing, the 

automaker relayed that simply releasing 

the accelerator pedal after FCW 

activation would not discern the actual 

effectiveness of the FCW system to alert 

the driver to brake, since there would be 

no large deceleration observed by the 

time the pedal was released. Instead, 

Toyota asserted that such an approach 

only serves to demonstrate CIB 

performance regardless of FCW 

activation. 

CAS asserted that it would only be 

appropriate to consolidate FCW and CIB 

testing if FCW is a part of the 

underlying CIB system (such that it 

utilizes identical physical components 

(e.g., sensors and brakes)), if it is 

provided every time CIB is activated 

(i.e., uses the same logic and parameters 

for system execution), and if capabilities 

for both systems can be ‘‘separately 

appreciated and evaluated’’ by users. 

Alternative 1—Conduct Multiple 

Separate FCW Assessments 

Honda favored combining FCW and 

DBS tests but stated if the Agency chose 

to keep FCW tests separate, it did not 

support any adjustment to the current 

FCW tests, unless other commenters 

suggested differently. Intel proposed to 

consolidate FCW and CIB testing but 

asserted TTCs should be revised and 

‘‘carefully selected’’ to limit nuisance 

activations if the Agency chooses to 

continue to conduct separate FCW 

assessments. Intel stated this was 


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95966 Federal Register / Vol. 89, No. 232 / Tuesday, December 3, 2024 / Notices 

particularly important for low SV 

speeds where a high TTC may be 

particularly annoying since a late 

reaction from the driver could still be 

reasonable and practicable. 

Like Honda and Intel, Bosch also did 

not support separate FCW assessments. 

As mentioned earlier, the company 

stated it would be challenging to define 

appropriate TTCs and other 

performance criteria for FCW only, and 

specifically requested that the current 

TTC for the LVD scenario (i.e., 2.4 

seconds) be revised because they 

considered it too difficult for current 

technology. 

Other commenters expressed that test 

criteria would have to change if the 

Agency opted to continue with separate 

FCW assessments. Auto Innovators, 

which supported the conduct of all 

three of the current FCW test scenarios 

if FCW assessments were not 

consolidated with those for AEB, 

mentioned that the SV headway should 

be increased if the current FCW tests 

were to be conducted at higher speeds. 

FCA opined that NHTSA should adjust 

the TTC criteria if it chooses to amend 

the test speed for the SV, but the 

automaker did not suggest appropriate 

TTC values. Likewise, Advocates 

generally mentioned that the Agency 

would have to specify TTCs, test speed, 

headway, etc. and present the data to 

support its selections to ensure FCW 

systems continue to elicit the intended 

driver response. 

Alternative 2—Perform One Indicant 

FCW Assessment 

If the Agency were to retain separate 

FCW assessments, FCA and CAS 

supported retaining all three current 

FCW test scenarios. CAS added that 

NHTSA should not reduce the number 

of test scenarios unless it could prove 

that doing so would not negatively 

affect safety. Advocates agreed that any 

reduction to the number of required 

tests should be supported by data. 

Furthermore, the group cautioned the 

Agency not to ‘‘seek convenience or 

expediency over the promotion of 

safety.’’ Instead, Advocates commented 

that NHTSA should test the range of 

conditions necessary to ensure FCW 

systems address the safety need and 

offer robust performance during realworld driving. They recommended the 

Agency establish minimum test criteria 

to ensure a baseline level of safety and 

use supplemental test criteria (e.g., 

assessments at higher or lower speeds, 

shorter headways, etc.) to assign 

additional credit to higher-performing 

systems. 

GM and Auto Innovators favored 

consolidating FCW, CIB, and DBS 

testing, as is done by other consumer 

programs, to permit assessment of FCW 

and AEB systems simultaneously and 

thus minimize test burden. However, if 

the Agency opted to assess FCW 

separately, the commenters favored 

retaining all three test scenarios (i.e., 

LVD, LVM, and LVS), as FCA and CAS 

proposed, to ensure (1) consistency with 

other NCAPs and that (2) FCW 

performance continues to align with the 

rear-end crash problem in the real 

world. 

Similar to GM and Auto Innovators, 

Honda supported consolidation of FCW 

and DBS tests. However, the 

manufacturer also acknowledged not all 

DBS systems may perform well at 

certain higher test speeds, such as 80 

kph (49.7 mph). Therefore, the 

manufacturer commented it may be 

necessary to perform one FCW test 

scenario independently at the maximum 

SV speed to appropriately evaluate FCW 

performance. 

Intel suggested the Agency should 

choose either the LVS or LVM test 

scenarios if NHTSA decides to require 

one test for FCW assessment. The 

company envisioned that procedural 

changes proposed for the CIB LVD test 

may be especially challenging for FCW 

systems as the prescribed headway (12 

m (39.4 ft.)) and POV deceleration (0.5g) 

will shorten the TTC substantially 

compared to that afforded currently in 

the FCW LVD test (i.e., 30 m (98.4 ft.) 

and 0.3 g POV deceleration). BMW also 

stated that the proposed LVS test 

scenario was the most appropriate 

scenario to select to evaluate FCW 

systems. 

Assessment Method, Number of Trials, 

and Pass Rate (for Separate FCW 

Assessments) 

Auto Innovators and FCA 

recommended that NHTSA should 

continue to conduct seven trials per 

scenario and maintain the pass rate of 

five out of seven trials if the Agency 

retains separate FCW tests. Intel also 

supported retaining multiple trials, 

stating that conducting three trials and 

adopting a pass rate of two out of three 

would limit test burden while still 

ensuring robust assessments. For the 

assessment method in general, the 

company proposed an approach that 

aligned with their comments to PAEB 

and AEB. 

Stating that FCW is not as important 

as AEB, IDIADA expressed that the 

Agency should award fewer points for 

FCW if separate assessments will be 

conducted for this technology. 

Accelerator Release Timing (Applicable 

for FCW Integration) 

With respect to the Agency’s proposal 

for release of the accelerator pedal if it 

was to integrate FCW and AEB tests, 

FCA stated a release time of 500 ms after 

the issuance of the FCW was 

appropriate. IDIADA also mentioned 

that a 500 ms pedal release time could 

be acceptable, as FCWs would ‘‘ideally’’ 

be issued 1.2 seconds prior to braking. 

However, Toyota did not agree with 

releasing the accelerator pedal 500 ms 

after issuance of the FCW if FCW and 

CIB testing was combined since, as 

mentioned previously, the commenter 

noted this approach would not assess 

the actual effectiveness of FCW, but 

rather, would just show the 

effectiveness of CIB. 

Intel suggested an alternative 

approach to validate FCW functionality. 

The company suggested NHTSA pursue 

a similar approach to that used by the 

General Safety Regulation (GSR), 

whereby the Agency would require an 

FCW be issued 0.8 seconds prior to the 

start of autonomous braking (as 

measured by the deceleration reaching a 

certain level). 

Auto Innovators suggested that 

NHTSA study drivers’ reaction times to 

determine whether releasing the 

accelerator pedal 500 ms after an FCW 

is issued is appropriate. The 

organization also opined that specifying 

0.5g as the threshold indicative of CIB 

braking in instances where no FCW is 

issued may be too high, such that the 

release of the accelerator pedal should 

potentially occur at a lower deceleration 

level. 

Response to Comments and Agency 

Decisions 

Based on the comments received, 

NHTSA has decided to consolidate FCW 

and AEB testing such that an assessment 

of FCW functionality will be assessed 

during NCAP’s CIB and DBS evaluations 

using LVD, LVS, and LVM test 

scenarios. During these evaluations, the 

SV must issue an FCW prior to the onset 

of automatic braking (as defined by the 

instant SV deceleration reaches at least 

0.15g) for each trial run performed. If an 

FCW is issued, the SV’s accelerator 

pedal will be fully released (at any rate) 

within 500 ms. For DBS testing, manual 

(i.e., robotic) braking will then be 

imparted 1.0 ± 0.1 seconds after 

issuance of the FCW. If no FCW is 

issued during a test trial, release of the 

SV accelerator pedal would not be 

required prior to impact with the POV 

(regardless of whether the vehicle’s AEB 

system offers automatic braking), and 

the SV will fail the trial run. See Figure 


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5 for sequence of FCW, throttle release, and brake application in the CIB and 

DBS evaluation tests. 

NHTSA notes that the requirement 

that an FCW be issued prior to the onset 

of automatic braking (as defined by the 

instant SV deceleration reaches at least 

0.15g) will not apply to the AEB false 

positive tests since issuance of an FCW 

and activation of automatic braking is 

not expected in these tests. If an FCW 

is issued in the CIB false positive test, 

the SV throttle will also be released 

within 500 ms, as this is an existing 

requirement for this test scenario. 

Likewise, per the existing CIB test 

procedure, if no FCW is issued during 

the CIB false positive test, the throttle 

will not be released until the test’s 

validity period (the time when all test 

specifications and tolerances must be 

satisfied) has passed. The Agency is also 

making no changes to throttle release 

timing or brake application for the DBS 

false positive test. As currently specified 

for this test, the SV throttle will be 

released within 500 ms of the currently 

prescribed TTC (2.1 seconds) if no FCW 

is issued by the specified time. If an 

FCW is issued, the SV throttle will be 

released within 500 ms of the alert. For 

both situations in the DBS test, the SV 

brakes will then be applied at a TTC of 

1.1 s, which corresponds to a nominal 

distance of 24.4 m (80.2 ft.). 

Integrating FCW Assessments Into AEB 

Testing 

The decision to evaluate FCW 

functionality during CIB and DBS 

evaluations using NCAP’s LVD, LVS, 

and LVM test scenarios differs slightly 

from the Agency’s March 2022 proposal. 

As mentioned earlier, NHTSA had 

proposed to integrate FCW into CIB 

testing in NCAP. At the time, the 

proposed combination of tests appeared 

to be the only viable option, (if the 

Agency was to consolidate FCW and 

AEB testing), since NHTSA had 

considered removing DBS testing from 

NCAP entirely or performing DBS 

testing at only a limited number of 

higher speeds. However, since the 

Agency has decided to retain DBS 

assessments in NCAP and will continue 

to perform DBS tests at multiple speeds, 

as discussed previously, evaluating 

FCW within DBS testing is also 

appropriate. NHTSA notes that FCA, 

Honda, and Toyota supported 

integrating FCW and DBS testing, 

suggesting that such an approach was 

more appropriate than integrating FCW 

and CIB testing. As Honda stated, FCW 

and DBS are designed to be 

complementary systems that operate 

sequentially to assist a driver in 

responding appropriately to prevent a 

rear-end collision. The FCWs the driver 

to the impending collision, the driver 

responds by braking, and the DBS 

system offers additional braking in 

instances where the driver’s braking 

alone is insufficient to avoid the crash. 

Therefore, it seems reasonable to 

evaluate FCW functionality (i.e., 

notification and timing) during NCAP’s 

DBS testing. 

Although CIB systems are designed to 

operate when the driver is unaware or 

unresponsive to an impending rear-end 

crash (i.e., the driver either does not 

respond to an FCW by braking or does 

not have time to brake after an FCW is 

issued), a vehicle should still issue an 

FCW in such situations. First, the 

vehicle cannot anticipate what actions 

the driver will take. Second, the 

warning serves to warn the driver not 

only of the crash threat but also of the 

onset of sudden profound braking, 

which can be alarming in itself. For 

these reasons the Agency has also 

decided to require the FCW be issued 

prior to automatic braking during 

NCAP’s CIB assessments. While the 

Agency acknowledges Toyota’s 

assertion that integrating FCW and CIB 

assessments ‘‘only serves to demonstrate 

CIB performance regardless of FCW 

activation,’’ the consolidation of FCW 

and CIB assessments permits an overall 

assessment of FCW functionality in 

situations where the driver may still 

find an alert to be beneficial. 

The requirement that an FCW be 

issued prior to the onset of automatic 

braking (as defined by the instant SV 

deceleration reaches at least 0.15g) will 

apply for all test speed and scenario 

combinations used during the conduct 

of the NCAP’s CIB and DBS evaluations, 

except for the false positive scenarios. 

By adopting this requirement, it is not 

necessary to calculate appropriate FCW 

TTCs for all AEB test conditions, as 

Auto Innovators and GM suggested. 

Rather, the presence of FCW will simply 

be assessed in the context of the AEB 

system as a whole. 

Although FCA expressed that 

automatic braking from CIB may be 

more effective at low speeds compared 

to driver braking and subsequent DBS 

intervention, NHTSA does not agree 

with the manufacturer that an FCW is 

not needed at lower speeds for a 

particular intervention method (i.e., 

automatic braking from CIB compared to 

driver braking and subsequent DBS 

engagement). For the reasons mentioned 

previously, an FCW should always be 

issued prior to automatic braking in the 

real-world situations represented by the 

Agency’s AEB testing. Additionally, 

well-designed FCWs can provide 

significant safety benefits in crashimminent rear-end crash scenarios. 

NHTSA encourages vehicle 

manufacturers to present them so that 

the driver may be able to respond with 

sufficient time to avoid a crash (i.e., not 

to solely rely on CIB activation for crash 


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I FCWonset I The throttle must I Manual 

be released at any braking is 

I occurs. l rate by this time. I applied. 

t SO0ms i 500 ms ± 100 ms j 1 second ± 0.1 second 

Figure 5: FCW, Throttle Release, and Brake Application Sequence in the CIB and DBS Tests 
95968 Federal Register / Vol. 89, No. 232 / Tuesday, December 3, 2024 / Notices 

167NHTSA notes that, pursuant to other changes 

made in this notice, the onset of automatic braking 

will be defined as 0.15g instead of 0.5g for NCAP’s 

future AEB tests. 

168https://www.regulations.gov/document/ 

NHTSA-2021-0002-0002. 

avoidance). That being said, the Agency 

is not prescribing that the FCW be 

issued at a specific time prior to braking 

in each test, as several commenters 

recommended. NHTSA should afford 

manufacturers with flexibility in this 

regard so they may design systems that 

are most appropriate for the 

complexities of various crash situations, 

some of which may provide very little 

time for a driver to take action to avoid 

a crash. Although the Agency reasons a 

requirement that an FCW be issued 

prior to automatic braking is appropriate 

for pre-defined scenarios during track 

testing, it does not want to be overly 

prescriptive such that automatic braking 

is suppressed in certain situations 

during real-world driving, such as when 

a lead vehicle cuts immediately in front 

of an AEB-equipped vehicle, where it 

may not be appropriate to delay 

immediate automatic braking in 

anticipation of a driver warning. 

NHTSA acknowledges BMW’s and 

Auto Innovators’ recommendation that 

the Agency combine FCW, CIB, and 

DBS assessments into one test series 

consisting of multiple test scenarios to 

assess the total safety provided by the 

systems collectively; however, this is 

not feasible given the Agency’s desire to 

provide assurance of both CIB and DBS 

system functionality. Driver-imparted 

manual braking may not be provided in 

all real-world situations; thus, it is 

beneficial to evaluate the performance 

of CIB systems devoid of DBS 

intervention. Further, the Agency agrees 

with FCA’s assertion that manufacturers 

may choose to execute CIB differently 

when the driver is attentive and 

responsive (i.e., situations represented 

by DBS testing) compared to when they 

are not (i.e., situations represented by 

CIB testing). The Agency aims to ensure 

system effectiveness in both situations. 

Conducting Separate FCW Assessments 

The Agency has decided not to 

conduct separate FCW assessments. 

NHTSA’s decision to expand upon its 

proposal to evaluate FCW functionality 

in both CIB and DBS assessments aligns 

well with recommendations made by 

many commenters, including Auto 

Innovators, Bosch, BMW, and GM. 

Respondents supported integration of 

FCW, CIB, and DBS testing for various 

reasons, including harmonization and a 

reduction in test burden. As mentioned 

by commenters, FCW is designed to 

work in a sequential manner with AEB, 

and AEB provides additional safety 

benefits compared to FCWs alone. 

Therefore, NHTSA reasons it is no 

longer necessary to assess FCW 

independent of AEB. Although Honda 

supported FCW and AEB consolidation, 

the commenter also asserted it may be 

necessary to perform one separate FCW 

test to assess system functionality at 

higher speeds (i.e., 80 kph (49.7 mph)) 

since not all DBS systems may perform 

well when tested. Similarly, NTSB 

suggested that NHTSA pursue FCW 

assessments at test speeds in excess of 

80 kph (49.7 mph). Since the Agency 

will perform LVS and LVM DBS 

assessments for test speeds of 80, 90, 

and 100 kph (49.7, 55.9, and 62.1 mph), 

and vehicles will be required to issue an 

FCW prior to automatic braking for all 

AEB test conditions to be evaluated 

(except for the false positive test 

conditions), it is unnecessary to conduct 

a separate high-speed assessment 

specifically to evaluate FCW 

functionality. Vehicles unable to meet 

the Agency’s FCW requirement will fail 

an AEB test trial. 

Accelerator Release Timing 

The Agency has decided to proceed 

with adopting its proposal for 

accelerator release timing. The SV’s 

accelerator pedal will be fully released 

at any rate within 500 ms after an FCW 

is issued during all CIB and DBS 

evaluations using LVD, LVS, and LVM 

test scenarios. This timing is consistent 

with that specified in NCAP’s current 

CIB and DBS test procedures, and the 

approach (i.e., releasing the throttle after 

the FCW is issued) matches that 

prescribed in Euro NCAP’s AEB Car-toCar systems test protocol. The Agency 

notes Euro NCAP specifies the pedal be 

released 1.0 second after issuance of the 

FCW during manual braking tests. Since 

NHTSA’s test laboratories have not 

experienced difficulties with releasing 

the accelerator pedal within 500 ms, as 

currently specified in the current test 

procedure, the Agency sees no reason to 

adopt Euro NCAP’s requirement instead. 

Loosening the requirement would only 

serve to increase the likelihood that an 

accelerator pedal application may 

interfere with AEB engagement. 

Although NHTSA had also proposed 

that the SV accelerator pedal would be 

fully released within 500 ms after the 

onset of automatic braking (as defined 

in the Agency’s proposal as the instant 

SV deceleration reaches at least 0.5g) 167

for CIB and DBS tests if no FCW is 

issued, this additional requirement is 

seemingly unnecessary since the 

Agency has decided that a vehicle 

would fail a trial in such instances. As 

such, if no FCW is issued during a CIB 

or DBS evaluations using LVD, LVS, or 

LVM test scenarios, release of the SV 

accelerator pedal would not be required 

prior to impact with the POV. 

For false positive testing, as stated 

earlier, the SV accelerator pedal will be 

released within 500 ms of an FCW if one 

is issued in the CIB false positive test; 

however, if no FCW is issued, the 

accelerator pedal will not be released 

until the test’s validity period has 

passed. For the DBS false positive test, 

the SV accelerator pedal will be released 

within 500 ms of the currently 

prescribed TTC (2.1 seconds) if no FCW 

is issued by the specified time; if an 

FCW is issued, the SV throttle will be 

released within 500 ms of the alert. 

Defining the Onset of Automatic 

Braking 

While there is no need to define the 

term ‘‘onset of automatic braking’’ for 

the purpose of releasing the accelerator 

pedal (given the decisions made herein), 

a definition of the term is needed to 

determine whether a vehicle’s FCW 

timing meets the adopted requirements 

for passing performance. Instead of 

defining the onset of automatic braking 

as 0.5g, as proposed, the Agency has 

decided to define the onset of automatic 

braking as a deceleration of 0.15g. 

NHTSA agrees with Auto Innovators 

that a 0.5g threshold may be too high. 

The Agency now reasons a 0.15g 

threshold is appropriate based on its 

experience conducting AEB testing for 

NCAP. This value has proven to be a 

reliable marker for AEB onset during the 

program’s track testing.168 As will be 

discussed, a vehicle cannot pass an 

NCAP AEB LVS, LVM, or LVD test trial 

unless the required FCW is presented 

prior to the onset of automatic braking 

(i.e., CIB), as defined by the instant SV 

deceleration reaches at least 0.15g. 

Since NHTSA has decided to integrate 

FCW and AEB testing rather than 

conduct separate FCW assessments, the 

Agency does not see the need to address 

comments received in this regard that 

are specific to an appropriate 

assessment method, number of trials, 

and pass rate solely for FCW. 

b. FCW Signal Modalities 

Currently, NHTSA gives credit to 

vehicles having FCW systems that send 

visual, auditory and/or haptic warning 

signals that meet the TTC requirements 

outlined in NCAP’s FCW test procedure. 

The Agency’s research has provided 

mixed results surrounding warning 

signal effectiveness. In one study, the 

Agency found that presenting drivers 

with an auditory warning in medium or 


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169Lerner, N., Robinson, E., Singer, J., Jenness, J., 

Huey, R., Baldwin, C., & Fitch, G. (2014, 

September), Human factors for connected vehicles: 

Effective warning interface research findings 

(Report No. DOT HS 812 068), Washington, DC: 

National Highway Traffic Safety Administration. 

170Forkenbrock, G., Snyder, A., Heitz, M., 

Hoover, R. L., O’Harra, B., Vasko, S., and Smith, L. 

(2011, July), A Test Track Protocol for Assessing 

Forward Collision Warning Driver-Vehicle Interface 

Effectiveness (Report No. DOT HS 811 501), 

Washington, DC: National Highway Traffic Safety 

Administration. 

171Flannagan, C., LeBlanc, D., Bogard, S., 

Nobukawa, K., Narayanaswamy, P., Leslie, A., 

Kiefer, R., Marchione, M., Beck, C., and Lobes, K. 

(2016, February), Large-scale field test of forward 

collision alert and lane departure warning systems 

(Report No. DOT HS 812 247), Washington, DC: 

National Highway Traffic Safety Administration. 

172NHTSA proposed that it would give credit to 

FCW systems that have both passing auditory and 

haptic alerts if both alert types were available. 

However, if a vehicle with such a system provided 

only a passing haptic alert and the Agency decided 

only to give credit to systems that provided passing 

auditory alerts, then the vehicle would not receive 

credit as having met the Agency’s FCW test 

requirements. 

173 87 FR 13477. 

174https://www.regulations.gov/comment/ 

NHTSA-2021-0002-1530. See footnote 15. 

175https://www.regulations.gov/comment/ 

NHTSA-2021-0002-1530. See footnote 16. 

high urgency situations significantly 

reduced crash severity relative to visual 

and tactile (or haptic) warnings.169

However, in other research studying the 

response of distracted human subjects to 

FCWs in forward collision crash 

scenarios on a test track, NHTSA found 

that 15 of the 17 total crashes that were 

successfully avoided (88 percent) 

occurred during trials performed with a 

seat belt pretensioner-based haptic alert. 

Only one crash was avoided during a 

trial performed with a beep-based 

auditory-only alert.170 Research 

conducted by other entities has also 

suggested that haptic warning signals 

may increase consumer acceptance of 

FCW technologies compared to auditory 

alerts.171

Based on these findings, the Agency 

sought comment on whether it should 

give credit to vehicles equipped with 

FCW systems that only provide a 

passing auditory warning or whether it 

should also give credit to those FCW 

systems that only provide passing 

haptic signals (if it chose to retain one 

or more separate FCW tests).172 NHTSA 

questioned whether haptic warning 

signals can be accurately and objectively 

assessed, and if so, whether certain 

haptic signal types should be excluded 

from consideration (if the Agency was to 

award credit to vehicles with haptic 

warnings that pass NCAP tests) because 

they may be a nuisance to drivers such 

that they would be more likely to 

disable them. NHTSA further 

questioned whether, for separate FCW 

evaluations, it should no longer give 

credit to FCW-equipped vehicles that 

offer only visual FCW signals. Finally, 

the Agency sought comment on what 

type(s) of FCW signal(s) would be 

acceptable for use in defining the timing 

of the release of the SV accelerator pedal 

if the Agency decided to assess the 

sufficiency of an FCW in the context of 

CIB (and PAEB) tests in lieu of separate 

FCW assessments. 

Summary of Comments 

Allow All Warning Signal Modalities 

Those in favor of not restricting the 

type of FCW signal modality permitted 

during Agency testing included CAS, 

HATCI, and Intel. HATCI stressed the 

importance that NHTSA be flexible with 

respect to warning signal type(s), 

contending that ‘‘[current] flexibilities 

allow industry to optimize and adjust 

the alerts based on the multitude of 

ADAS technology installed, the 

interaction between the technologies, 

and research and development 

findings.’’ The manufacturer warned 

that restricting system warning signals 

to specific modalities may limit future 

alert strategies (e.g., combinations, 

locations) and have unintended 

consequences (e.g., reduced alert 

effectiveness) as ADAS technology 

evolves and other systems are 

introduced. Instead of prescribing alert 

types, HATCI suggested that NHTSA 

work with industry and/or established 

standards bodies (e.g., Society of 

Automotive Engineers, or SAE) to define 

process-based and/or performancebased methods to assess alert 

effectiveness. 

Intel mentioned that modality should 

not be restricted since credit should be 

based on warning effectiveness (i.e., a 

warning resulting in passing 

performance is effective, regardless of 

the signal modality). CAS agreed that 

any effective implementation of warning 

signal type(s) should be considered 

acceptable since FCW activation during 

real-world driving should rarely occur. 

Restrict Warning Signal Modalities 

A few commenters recommended the 

Agency award credit only to certain 

FCW signal modalities. MEMA, FCA, 

Bosch, and Subaru stated that credit 

should be awarded for only auditory or 

haptic warnings. Although Bosch 

supported awarding credit for both 

auditory and haptic warnings and 

considered itself to be ‘‘technology 

agnostic’’ in general, the company also 

reasoned that haptic warnings are more 

likely to seize the attention of the driver. 

If a specific haptic warning (e.g., 

steering wheel vibration) is 

implemented for a specific technology 

(e.g., FCW), Bosch asserted strongly that 

the same haptic warning (e.g., steering 

wheel vibration) should not also be 

paired to a different technology (e.g., 

BSW) to avoid confusing the driver. 

Subaru stated that credit should be 

awarded to auditory and haptic FCW 

signals since they are the most effective. 

The company cited the Agency’s 

research findings pertaining to the 

effectiveness of auditory warnings 

versus visual and haptic warnings 

referenced in its March 9, 2022, RFC 

Notice 173 (and above) as justification to 

award credit to auditory warnings. 

NTSB supported awarding credit to 

vehicles offering auditory unimodal 

FCW or bimodal FCWs that include an 

auditory component. In general, the 

commenter did not support awarding 

credit to vehicles offering haptic FCW 

signals as the group noted that there is 

large variation in the implementation of 

haptic warnings (e.g., seat, steering 

wheel, seat belt); therefore, it would not 

be prudent to assume equivalent 

effectiveness without supporting 

research. Finally, ZF Group suggested 

the Agency should award credit to 

haptic seatbelt warnings when 

considering approved warning signal 

modalities, as their research has shown 

them to be highly effective. 

Add Requirements to Visual Warning 

Signals or Require Multiple Modalities 

Several commenters, including NTSB 

and DRI, remarked that visual-only 

warnings should not be considered 

acceptable to earn FCW credit. NTSB 

cited the low effectiveness of visualonly warnings as the reason not to 

award credit to visual FCWs.174 The 

group also referenced several crash 

investigations where visual warnings 

failed to capture drivers’ attention when 

the vehicle was operating in partial 

automation mode at the time of the 

crash.175

DRI also suggested the Agency 

discontinue the acceptance of visual 

warnings or ‘‘alternatively prescribe 

minimum characteristics of the alerts 

(size, color, brightness, location)’’ to 

gain the driver’s attention. The test 

laboratory stated that in many FCW 

systems, the visual warning signal, 

which is typically a telltale in the 

instrument panel that changes color, is 

‘‘too small,’’ appears in ‘‘non-attentioncapturing colors (e.g., white),’’ or is 

otherwise inconspicuous. The company 

also reasoned that a distracted driver’s 

gaze would likely not be forwardlooking, such that a visual warning 

located in the instrument panel would 


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95970 Federal Register / Vol. 89, No. 232 / Tuesday, December 3, 2024 / Notices 

176https://www.regulations.gov/comment/ 

NHTSA-2021-0002-3856. See Appendix 2 for 

rationale and supporting data. 

177 DOT HS 812 247. 

not capture the driver’s attention as well 

as an auditory or haptic warning. 

However, DRI suggested that a large, 

bright visual warning in an attentioncapturing color, such as red, may 

suffice. DRI further surmised that a 

visual FCW is often intended to be an 

indicator to a driver regarding the ‘‘real’’ 

alert, which may be auditory or haptic, 

such that it serves to ‘‘communicate 

visually to the driver why they are 

hearing a warning beeping, rather than 

[the visual alert] being a warning in and 

of itself.’’ As such, the laboratory, along 

with an anonymous commenter, opined 

that visual FCWs are not effective at 

warning the driver unless they are 

combined with an auditory or haptic 

warning signal. IDIADA agreed that 

visual warnings alone are insufficient to 

capture the driver’s attention since they 

may not be looking at the instrument 

panel, and as such, recommended the 

Agency award credit to vehicles offering 

a combination of visual and auditory 

warnings. 

GM stated that multimodal (e.g., 

visual plus directional auditory or 

directional haptic) warnings are 

necessary for ‘‘imminent’’ crash 

warnings, but visual-only signals are 

acceptable for ‘‘cautionary’’ crash alerts. 

The manufacturer suggested that 

multimodal warnings may increase 

consumer acceptance and limit 

instances of drivers turning off FCW 

systems due to annoyance. However, 

GM opined that NHTSA should only 

provide credit to vehicles in NCAP 

testing offering multimodal FCWs that 

include both a visual and haptic or 

auditory signals. Like DRI, GM also 

suggested the Agency impose additional 

requirements for visual warning signals, 

recommending that visual alerts should 

explain the nature of the warning and 

should be located such that they ‘‘draw 

the driver’s attention to the general 

direction of the crash threat.’’ This 

directional requirement, referenced 

previously, was also suggested for 

haptic and auditory components of 

multimodal warnings. The manufacturer 

suggested that acceptable visual FCWs 

should include a ‘‘red flashing 

imminent alert and be placed in the 

lower, center portion of the driver’s 

forward field-of-view,’’ like a 

translucent red flashing alert reflected 

on the lower part of the vehicle’s 

windshield, to draw the driver’s 

attention forward, in the direction of the 

crash threat, stating this may facilitate a 

rapid, appropriate response by the 

driver. 

With respect to haptic warnings, GM 

suggested the Agency should award 

additional credit to their Safety Alert 

Seat (SAS) vibration alerts, and to other 

haptic alerts shown to support 

equivalent rationale.176 According to 

GM, SAS vibration alerts are triggered 

simultaneously with an auditory alert 

by the same ADAS signal and can be 

detected by various means during 

testing (e.g., voltage readings, vibration 

sensors, auditory microphone, etc.). GM 

explained they allow non-visual crash 

alerts to be detected by hearingimpaired drivers, thus improving 

accessibility. GM further stated a largescale telematics-based study funded by 

NHTSA found that, compared to 

auditory warnings, SAS warnings 

produced braking at the same time after 

issuance of an FCW, were preferred by 

drivers, and increased usage of not just 

the FCW system overall, but also the 

most conservative alert timing setting 

(i.e., ‘‘Far’’).177

Several other commenters (BMW, 

Subaru, Rivian, and Auto Innovators) 

also favored systems offering 

multimodal warning strategies, 

specifically auditory or haptic warning 

signals in combination with visual 

signals. Auto Innovators suggested that 

vehicles having haptic or auditory 

warnings could receive a greater number 

of points than those offering only visual 

warnings if the Agency was to 

implement a rating system for FCWs. 

Similarly, Subaru supported awarding 

more points to FCW systems that 

provide a combination of warning signal 

modalities. Rivian suggested that drivers 

could be given the option to turn off 

either the auditory or haptic warning to 

suit their preference. To limit driver 

nuisance, the commenter stated NHTSA 

should provide a recommended decibel 

level for auditory warnings and a 

recommended type and location for 

haptic warning signal presentation, but 

not restrict system designs. As stated 

previously, NTSB also implied that 

bimodal auditory warnings (i.e., 

auditory plus visual) would be 

preferred. 

Other Related Comments 

Auto Innovators requested that the 

Agency clarify what constitutes an alert. 

Specifically, the group asked whether 

alerts at the steering wheel, driver’s seat, 

and pedal qualify as haptic alerts, in 

addition to system-induced vehicle 

braking at low deceleration levels (i.e., 

partial braking). The commenter 

mentioned that, per Euro NCAP’s 2023 

update, the organization now considers 

partial braking to be an approved haptic 

warning. DRI posed a similar question. 

The commenter cited section 11.5.2.4 of 

the Agency’s FCW test procedure, 

which states, ‘‘The FCW system shall 

provide a warning to the driver by 

presenting an auditory alert, visual alert, 

haptic vibration, haptic vehicle cue 

(e.g., braking vibration, steering 

vibration, or seat vibration),’’ and asked 

whether the Agency intended to include 

‘‘a brake tug,’’ defined as a short (0.3 

seconds) system-supplied braking at a 

low, 0.2 g deceleration, as a valid 

warning modality. DRI stated it 

considers ‘‘a brake tug’’ to be an 

effective FCW that should be accepted. 

Advocates recommended that the 

Agency conduct research to identify 

which FCW warning signal modalities 

will increase use, reduce dissatisfaction, 

and be most effective at reengaging the 

driver and eliciting a safe, timely, and 

appropriate response. The organization 

also suggested there may be further 

benefit realized from standardizing 

warnings, especially for drivers that use 

multiple vehicles. 

Response to Comments and Agency 

Decisions 

FCWs Must Include Auditory and 

Visual Signals 

Based on the comments received and 

the general support for use of a 

multimodal FCW strategy, the Agency 

has decided that a vehicle must present 

a forward collision warning consisting 

of auditory and visual warning signals 

to the vehicle operator to receive credit 

in each of NCAP’s LVD, LVM, and LVS 

AEB tests. 

Use of a multimodal FCW will ensure 

most drivers will perceive the warning 

as soon as it is presented, allowing the 

most time for the driver to take evasive 

action to mitigate or, if possible, avoid 

a crash. Further, a multimodal FCW 

strategy is consistent with the 

recommendations of multiple U.S. and 

international organizations, including 

Euro NCAP, the ISO, and SAE 

International. ISO recommends a 

multimodal approach in both ISO 

15623, ‘‘Forward vehicle collision 

warning systems—Performance 

requirements and test procedures,’’ and 

ISO 22839, ‘‘Forward vehicle collision 

mitigation systems—Operation, 

performance, and verification 

requirements’’ (which applies to light 

and heavy vehicles). SAE addresses the 

topic of a multimodal FCW strategy in 

both information report J2400 2003–08, 

‘‘Human Factors in Forward Collision 

Warning Systems: Operating 

Characteristics and User Interface 

Requirements,’’ and J3029, ‘‘Forward 

Collision Warning and Mitigation 

Vehicle Test Procedure and Minimum 


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Federal Register / Vol. 89, No. 232 / Tuesday, December 3, 2024 / Notices 95971 

178TFCW is determined by the auditory portion of 

the warning in Euro NCAP’s test procedure. 

179Campbell, J.L., Brown, J.L., Graving, J.S., 

Richard, C.M., Lichty, M.G., Sanquist, T., . . . & 

Morgan, J.L. (2016, December). Human factors 

design guidance for driver-vehicle interfaces 

(Report No. DOT HS 812 360). Washington, DC: 

National Highway Traffic Safety Administration. 

180These examples of ‘‘haptic vehicle cues’’ are 

currently permitted under Section 11.5.2.4 of 

NCAP’s current FCW test procedure. See Docket 

No. NHTSA–2006–26555–0134. 

181Euro NCAP Assessment Protocol—Safety 

Assist, Collision Avoidance, Version 10.4. 

December 2023. 

182NHTSA clarifies that FCW onset would be 

determined via measurement of the FCW auditory 

signal sound output within the vehicle cabin and 

the illumination of the FCW visual signal. CAN bus 

information would not be used to assess FCW onset. 

Performance Requirements—Truck and 

Bus (2015–10; Work in Progress 

currently).’’ 

While no one signal combination was 

preferred by commenters, NHTSA’s 

decision to impose a standardized 

auditory plus visual alert strategy for 

NCAP is appropriate given most of these 

organizations’ recommendations specify 

an FCW consisting of auditory and 

visual signals, though ISO 15623 

specifies that an FCW include a visual 

warning as well as an auditory or haptic 

signal. Euro NCAP also defines an FCW 

as an audio-visual warning.178 The 

Agency’s decision to adopt a combined 

auditory/visual bimodal alert aligns 

well with its ‘‘Human factors design 

guidance for driver-vehicle interfaces’’ 

report,179 which contains best practice 

information for implementation of 

various alerts, including those for FCW. 

Based on cited research, the report 

suggests ‘‘collision avoidance 

performance for both forward and side 

object collisions may be best when a 

bimodal auditory/visual warning system 

is used, which extends across driving 

scenarios, types of collisions, and driver 

populations.’’ Requiring a bimodal 

auditory/visual alert also seems 

reasonable considering FCWs comprised 

of auditory and visual signals are 

prevalent in current U.S. vehicle 

models, thus limiting manufacturer 

burden. 

The Agency recognizes that multiple 

commenters sought flexibility for 

automakers to use an FCW of their own 

preference in lieu of one prescribed by 

NHTSA to optimize warning strategies 

for other technologies in the future. 

However, as Advocates suggested, 

standardizing FCW signal modalities 

may simplify a consumer’s 

understanding of these warnings while 

hastening a driver’s recognition, and 

thus, response, to them. As commenters 

provided no data concerning 

consumers’ degree of understanding of 

the wide variety of FCW 

implementations currently—they 

simply made generalized statements 

about consumer familiarity—NHTSA 

does not view these arguments as 

sufficient to overcome the value of 

standardization as a means of ensuring 

consumer familiarity with FCWs. FCW 

components that differ by manufacturer 

and across models may cause confusion 

for drivers, especially when driving 

new, unfamiliar, or rental vehicles. 

Consistency of alerts to the extent 

possible should improve a driver’s 

ability to quickly comprehend the 

nature of the alert and the reason behind 

any AEB intervention. Although 

NHTSA acknowledges that studies exist 

which suggest that, depending on 

design, alternative warning types (i.e., 

visual and haptic, auditory and haptic, 

or haptic-only) can also be effective, 

without overwhelming data to suggest 

that one of these alert types/ 

combinations is more effective than a 

combined auditory/visual FCW, 

ensuring standardization of a familiar 

alert option would best serve 

consumers. 

Option To Include Supplementary 

Haptic Signal 

Although the Agency will require a 

combined auditory/visual FCW, a 

vehicle may additionally present a 

haptic signal to warn of an impending 

collision without penalty. As several 

commenters noted, some vehicle 

manufacturers incorporate a haptic 

component into their products’ FCWs. 

These may include vibrations in the 

steering wheel, driver’s seat, and/or 

pedal, ‘‘tugs’’ on the driver’s seat belt, 

or system-induced vehicle braking at 

low deceleration levels (i.e., partial 

braking), including ‘‘brake tugs.’’ 180

There is no current evidence to show 

that haptic FCW signals themselves are 

detrimental to safety. In fact, Euro 

NCAP awards extra human machine 

interface (HMI) credit to systems 

offering supplementary haptic alerts 

that meet certain criteria.181 Thus, the 

Agency does not want to discourage 

manufacturers from incorporating 

haptic alerts as an optional addition if 

they so choose. That said, NHTSA 

advises vehicle manufacturers to 

carefully implement haptic signals such 

that they will not be confused with 

those currently used for other crash 

avoidance technologies, such as those 

related to lane keeping or blind spot 

detection. The issuance of an FCW will 

not be considered complete during 

NCAP tests until both auditory and 

visual components are provided. 

Warning Signal Timing 

During DBS tests performed with 

LVD, LVM, and LVS scenarios, release 

of the SV’s accelerator pedal will not be 

initiated (and thus, the brake will not be 

applied) until after issuance of the 

required auditory and visual signals. 

However, a vehicle cannot pass a DBS 

test trial unless the two required FCW 

signals are presented prior to the onset 

of automatic braking (i.e., CIB), as 

defined by the instant SV deceleration 

reaches at least 0.15g.182 In other words, 

if automatic braking stemming from CIB 

occurs prior to the issuance of either 

signal (auditory or visual) from the 

required bimodal FCW, the vehicle will 

fail a test trial even if it does not make 

contact with the vehicle test device. 

However, if automatic braking from CIB 

occurs prior to the application of 

manual braking used to assess DBS but 

after the required FCW signals are 

presented, the vehicle can pass a test 

trial if it does not contact the POV. 

NHTSA reasons that this procedural 

requirement not only aligns with the 

intent of DBS tests (i.e., for an 

inattentive driver to respond to the FCW 

by braking prior to CIB system 

intervention), but it should also make 

certain that the driver is presented with 

a warning with sufficient time to react 

to an impending rear-end crash even if 

CIB intervention begins relatively soon 

after the FCW is issued. In addition, it 

should ensure a vehicle’s FCW affords 

real-world effectiveness. If one or more 

of the required components of the 

bimodal FCW are not issued, release of 

the SV accelerator pedal would not be 

required prior to impact with the 

vehicle test device (i.e., POV). 

NHTSA is requiring that both FCW 

signals be issued before the accelerator 

pedal is released in DBS tests because, 

as DRI asserted with respect to visual 

cues, for bimodal alerts, one FCW signal 

often serves as a secondary, 

confirmatory indication that explains to 

the driver what the primary signal is 

intended to communicate (i.e., a 

forward crash-imminent situation). 

Therefore, it seems reasonable to require 

both signals be issued to provide a 

timely response so the driver can 

recognize the purpose of the FCW, 

release the accelerator, and brake. 

While the Agency’s CIB test 

represents a different real-world 

situation compared to its DBS test, 

adopting a similar test approach for CIB 

is reasonable. As mentioned, NHTSA’s 

DBS tests represent situations where an 

inattentive driver re-engages in the 

driving task in response to an FCW (or 

simply in response to noticing a crashimminent situation) and applies the 

brakes to avoid or mitigate a rear-end 


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95972 Federal Register / Vol. 89, No. 232 / Tuesday, December 3, 2024 / Notices 

183Nodine, E., Fisher, D., Golembiewski, G., 

Armstrong, C., Lam, A., Jeffers, M.A., Najm, W., 

Miller, S., Jackson, S., and Kehoe, N. (2019, May), 

Indicators of driver adaptation to forward collision 

warnings: A naturalistic driving evaluation (Report 

No. DOT HS 812 611), Washington, DC: National 

Highway Traffic Safety Administration. 

184European New Car Assessment Programme 

(Euro NCAP) (December 2023), Test Protocol—AEB 

Car-to-Car systems, Version 4.3. See section 7.4.1.1. 

crash. On the other hand, the Agency’s 

CIB tests are designed to represent 

situations in which the driver does not 

brake. For instance, the driver may 

respond to the FCW by releasing the 

throttle but still fail to manually apply 

the brake pedal. Since the vehicle 

cannot anticipate what actions the 

driver will or will not take in a crashimminent situation, the Agency expects 

that an FCW would/should always be 

issued. In situations where the driver 

does not respond by braking (such as 

those represented by NHTSA’s CIB 

tests), the alert serves to inform the 

driver that the vehicle is going to 

intervene. As such, for NHTSA’s LVD, 

LVM, and LVS CIB testing, like for its 

DBS tests, the Agency will release the 

SV’s accelerator pedal after the issuance 

of both FCW components (i.e., the 

visual and auditory signal), and a 

vehicle will fail a CIB test trial (even if 

it does not contact the vehicle test 

device) if both FCW signals are not 

issued prior to the onset of automatic 

braking (i.e., CIB), as defined by the 

instant SV deceleration reaches at least 

0.15g. Furthermore, if one or more of the 

two required alert signals from the 

bimodal FCW are not issued, release of 

the SV accelerator pedal would not be 

required prior to impact with the 

vehicle test device (i.e., POV). 

Additional Requirements for Specific 

Warning Signal Types 

At this time, the Agency is not 

prescribing additional requirements for 

visual or auditory warning signals (e.g., 

color, location, decibel level, type, etc.) 

as some commenters suggested, and it is 

not standardizing FCW beyond defining 

signal types, as requested by Advocates. 

It is outside the scope of NCAP (a 

consumer information program) to be 

prescriptive in this regard. 

c. Adjustable Setting for FCW/AEB 

NCAP’s current FCW test procedure 

states that if an FCW system provides a 

warning timing adjustment setting for 

the driver, at least one timing setting 

must meet the TTC warning criteria 

specified in the procedure. Therefore, if 

a vehicle is equipped with a warning 

timing adjustment, only the most 

conservative (i.e., earliest) warning 

setting is presently tested. However, in 

its March 2022 RFC notice, the Agency 

acknowledged that while selecting the 

most conservative setting is beneficial 

for track testing where the driver of the 

SV must steer and/or brake to avoid a 

crash with the POV after the FCW is 

issued, another setting may be more 

appropriate for NCAP evaluation. 

NHTSA recognized that many 

consumers may not adjust the warning 

timing setting for FCWs, and those that 

do may be unlikely to select the earliest 

setting since this setting is most likely 

to result in false positive warnings (i.e., 

nuisance warnings) during real-world 

operation.183 The Agency also expressed 

that selecting the earliest (i.e., most 

conservative) FCW setting may allow a 

vehicle to pass NCAP’s FCW test, 

whereas later warning settings may not 

earn NCAP credit. Accordingly, NHTSA 

voiced concern that its FCW test results 

for such vehicles may not accurately 

represent drivers’ real-world 

experiences. 

Based on these considerations, the 

Agency proposed to test the middle (or 

next latest) FCW system setting when 

performing FCW (and AEB/PAEB) 

NCAP tests on vehicles that offer 

multiple FCW timing adjustment 

settings. Selection of the middle or next 

latest warning setting for testing would 

harmonize with Euro NCAP’s AEB Carto-Car systems test protocol, thus 

potentially driving costs down for 

manufacturers and attempting to ensure 

that consumers in both the U.S. and 

European markets benefit from similar 

FCW system settings.184 The Agency 

noted that the proposed procedural 

change would uphold the mandate in 

the BIL that NHTSA consider 

harmonization with third-party safety 

rating programs when practicable. 

NHTSA requested comments on 

whether testing the middle (or next 

latest) FCW system setting was 

acceptable or whether another setting 

would be more appropriate. 

Summary of Comments 

Middle or Next Latest Timing Setting 

Many commenters (FCA, Honda, 

Bosch, NTSB, Advocates, and NYC 

DOT/NYC DCAS, Vision Zero Task 

Force) suggested that the middle (or 

next latest) FCW system setting should 

be utilized for testing. Honda stated this 

setting was ‘‘the best compromise’’ to 

evaluate system capabilities. AAA also 

asserted the middle setting was most 

appropriate because it should be less 

likely to ‘‘bias system response relative 

to endpoint settings.’’ That said, the 

commenter also opined that if the 

system automatically reverts to a certain 

setting with each key cycle, that setting 

should be utilized for testing instead. 

NYC DOT/NYC DCAS, Vision Zero Task 

Force favored the middle (or next latest) 

FCW setting to ‘‘eliminate grade 

inflation’’ and ensure systems perform 

well under conditions consumers would 

expect them to. Advocates favored the 

middle or next latest setting to 

harmonize with Euro NCAP test 

protocols if such an approach did not 

negatively affect FCW safety benefits, 

such as if the vehicle exhibited a 

significant degradation in performance 

when an alternative alert setting was 

chosen, particularly if that setting was 

favored by the majority of consumers. 

Some commenters did not favor 

assessments that utilized the middle 

FCW setting. Intel stated that by 

choosing the middle setting, TTC 

thresholds may increase, which may be 

perceived as a nuisance by many drivers 

such that they would turn off the FCW 

system. The commenter suggested that 

the Agency could utilize the middle 

setting if it reduced the TTC 

requirements for the FCW tests. GM 

contended that if NHTSA was to select 

the middle setting for testing, 

automakers would alter FCW system 

designs accordingly to align current 

default settings to the test settings (i.e., 

middle) to limit the possibility of 

unexpected performance differences. 

If NHTSA was to choose the middle 

setting for testing, HATCI asked for 

clarification on what setting would be 

used if the vehicle has only two settings. 

Factory Default Timing Setting 

Several commenters stated that the 

Agency should select the factory default 

setting for testing purposes when driver 

configuration is available. BMW and 

Rivian mentioned that such system 

settings are rarely changed and therefore 

the default setting is most likely to be 

the one enabled. BMW commented that 

vehicle manufacturers should inform 

NHTSA of the default setting, and if 

such information is not provided, the 

Agency should utilize the middle (or 

next latest) setting during testing. As 

mentioned previously, Tesla also 

favored testing with the factory default 

setting (for any configurable FCW or 

AEB setting), contending that the 

default setting is the most-used setting 

by drivers, ‘‘best represents the vehicle 

manufacturer’s intended system 

performance,’’ and would best ensure 

consistency across vehicle models. The 

automaker mentioned that different 

settings may result in a 1.0 second 

variation (earlier or later compared to 

other settings) which would have 

varying impacts on performance. 

HATCI also proposed that NHTSA 

utilize the default system settings 

during testing. HATCI noted their 


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185 In a 2017–2019 study of nine focus groups 

involving 24 participants (58 percent female and 42 

percent male) from the Chicago, IL area, market 

research, and an online review focused on 

consumer perception of ADAS technologies, HATCI 

found that approximately 62 percent of consumers 

did not access or make changes to ADAS settings. 

186 DOT HS 812 247, ‘‘Large-Scale Field Test of 

Forward Collision Alert and Lane Departure 

Warning Systems,’’ 2016. 

research has shown that most Hyundai 

and Kia customers do not change ADAS 

settings after purchasing a new vehicle, 

and that changing the settings for testing 

purposes would likely not be most 

representative of most real-world 

driving situations.185 The automaker 

recommended that the Agency conduct 

a comparable fleet-wide study and use 

those findings for system settings to 

guide future test procedural changes. 

Similar to HATCI, GM asserted that 

testing with a setting other than the 

factory default setting would not best 

represent real-world customer selection. 

In a 2016 study of FCWs, the automaker 

found their default setting (i.e., ‘‘Far’’) 

was utilized 59 percent of the time 

compared to 17 percent for the 

‘‘Medium’’ setting and 15 percent for 

the ‘‘Near’’ setting.186 In 9 percent of 

cases, customers had turned the FCW 

system off even though a range of alert 

settings was available. From this, GM 

gleaned that the default setting aligns 

well with their customer preferences, 

and if customers had not been provided 

with a range of alert settings, more 

would have likely turned the FCW 

system off. Based on these findings, GM 

opined that utilizing the factory default 

setting for NCAP testing would 

challenge vehicle manufacturers to 

provide NCAP levels of performance at 

the setting choice most likely to be used 

by consumers while also limiting 

nuisance alerts. 

Alternative Timing Settings 

Some respondents, like CAS, 

mentioned that selecting the setting that 

is ‘‘least sensitive’’ is most appropriate 

since it would provide consumers with 

a sense of the ‘‘worst-case’’ protection 

offered by the system, while Auto 

Innovators recommended that the 

Agency allow the manufacturer to 

decide the setting to be tested to 

promote flexibility with respect to 

system design. Like Intel, the group 

asserted that requiring a specific setting 

may impact the upper and lower bounds 

of system performance and sensitivity 

and thus affect customer satisfaction. 

Auto Innovators stated that by allowing 

automakers to specify the test setting, 

consumer acceptance would not be 

affected, and the Agency could still be 

assured that at least one setting meets 

system performance requirements. 

Response to Comments and Agency 

Decisions 

The Agency has decided to adopt its 

March 2022 proposal for FCW timing 

settings in NCAP testing and will set 

FCW presentation timing to the middle 

(or next latest) setting during its AEB 

evaluations (see Figure 6). For FCW 

systems that have only two settings, as 

HATCI mentioned, the Agency will 

select the later setting for NCAP testing. 

NHTSA will apply a similar 

requirement to vehicles separately 

offering adjustments for AEB (e.g., early 

versus late intervention). 

Although many commenters 

recommended that the Agency select the 

default setting for its AEB tests, 

generally citing that it is the setting 

most likely to be utilized in real-world 

driving, selecting the middle (or next 

latest) setting is most appropriate for 

NCAP’s AEB testing program for several 

reasons. First, while there may be merit 

in selecting default settings for test 

evaluations, as noted in the Agency’s 

initial proposal, harmonization with 

other third-party safety rating protocols, 

most notably Euro NCAP, is desirable 

whenever practicable. Also, it is a 

reasonable expectation that the setting 

most preferred or often used by 

consumers would (or rather should) be 

the default setting and that this setting 

should generally fall in the middle of 

the range of driver setting preferences 

that span either earlier or later alert 

settings. In essence, the default setting 

for FCW systems is expected to 

correspond to the middle alert setting. 

As such, NHTSA is not concerned that 

vehicle manufacturers may choose to 

alter FCW system designs to align 

current default settings to the test 

settings (i.e., middle), as GM asserted. In 

fact, the Agency encourages this. As 

AAA mentioned, this should limit 

designs that bias system response 

toward either earlier or later settings. 

Along these lines, the Agency has 

decided against choosing the latest 

setting for NCAP’s AEB testing, as CAS 

suggested, even though it may identify 

worst-case performance. NHTSA does 

not want to encourage acceptable 

performance for only more aggressive 

settings that may be preferred by a 

limited number of drivers. Similarly, it 

has not opted to retain the most 


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later 

Settingl I 

1 Setting 2 

FCW will be set to the middle (or next latest) setting. 

Figure 6: Forward Collision Warning (FCW) Settings Used/or NCAP Testing 
95974 Federal Register / Vol. 89, No. 232 / Tuesday, December 3, 2024 / Notices 

187https://www.regulations.gov/comment/ 

NHTSA-2021-0002-1530. See footnote 14. 

188Cicchino, J.B. & Zuby, D.S. (2019, August), 

Characteristics of rear-end crashes involving 

passenger vehicles with automatic emergency 

braking, Traffic Injury Prevention, 2019, VOL. 20, 

NO. S1, S112–S118, https://doi.org/10.1080/ 

15389588.2019.1576172. 

189 In this instance, over-represented means a 

higher frequency as a percentage for AEB-equipped 

vehicles versus non-AEB-equipped vehicles on a 

normalized basis. 

conservative (or earliest) setting for 

NCAP’s tests. 

This is not to suggest that 

manufacturers should provide other 

FCW or AEB system settings which will 

afford little to no benefit, nor should 

any other setting negatively impact the 

performance of FCW and/or AEB. 

However, as NCAP is a consumer 

information program, NHTSA must 

provide comparable results in order for 

consumers to make informed 

purchasing decisions. Accordingly, it is 

selecting one timing setting for FCW 

and AEB systems, the middle (or next 

latest) setting, for NCAP’s AEB testing. 

Also, for vehicles that have an ESC off 

switch, NHTSA will keep ESC engaged 

for the duration of the test. 

As previously mentioned, NHTSA has 

decided to evaluate FCW in tandem 

with CIB and DBS. To pass a test trial 

in the Agency’s CIB or DBS evaluations 

that use LVD, LVM, and LVS scenarios, 

the SV must issue the required FCW 

signals (i.e., auditory and visual) prior 

to the onset of automatic braking (as 

defined by the instant SV deceleration 

reaches at least 0.15g). After the 

required FCW signals are issued, the 

SV’s accelerator pedal will be fully 

released (at any rate) within 500 ms. 

Additionally, for DBS test conditions, 

manual braking will be imparted 1.0 ± 

0.1 seconds after the complete, bimodal 

FCW is presented. Effectively, to 

perform well in the Agency’s AEB 

evaluations, the vehicle must issue the 

FCW in a timely manner so that the 

accelerator pedal can be released, and 

the brake can be applied (either 

automatically or manually), with 

sufficient time to allow the vehicle to 

avoid contacting the POV. By 

integrating FCW assessments in this 

way, NHTSA expects, as GM opined 

with respect to default settings, that 

vehicle manufacturers will inherently 

strive to limit nuisance alerts during 

real-world driving for the FCW timing 

setting preferred by most drivers while 

also performing well in NCAP’s AEB 

tests at this preferred setting. In essence, 

the Agency’s effort to integrate testing 

should help to eliminate the concern 

expressed by Intel that TTC thresholds 

(and inherently nuisance alerts) may 

increase if the middle timing setting is 

selected for testing. Since the 

functionality of FCW and AEB will be 

assessed holistically, manufacturers 

should ultimately be afforded more 

flexibility with respect to system design. 

They may establish the upper and lower 

bounds of the FCW system’s 

performance, deciding whether to either 

increase or reduce FCW TTCs to address 

customer satisfaction, and thus will 

effectively set the timing for the FCW 

setting to be tested (albeit the middle 

setting), as Auto Innovators requested. 

The resultant FCW and AEB system 

performance is markedly at their 

discretion. 

NHTSA also notes that, to receive 

credit for AEB, forward collision 

warning and automatic emergency 

braking technologies (i.e., FCW and AEB 

systems) must appear ‘Default ON’ 

during each ignition/key cycle. While 

the Agency is not prohibiting a 

disabling function for these technologies 

in its NCAP evaluation, it does not 

expect that the testing requirements 

imposed herein should result in 

reduced consumer satisfaction. Instead, 

NHTSA expects drivers will adjust their 

vehicle’s FCW and AEB system settings 

to meet their personal preferences 

instead of disengaging the systems 

altogether. 

3. Additional FCW and AEB Test 

Scenarios and Conditions 

a. Other FCW Scenarios or Test 

Conditions 

In its March 2022 RFC notice, NHTSA 

also requested comment on whether 

there were additional or alternative test 

scenarios or test conditions that it 

should consider incorporating into an 

updated FCW test procedure for NCAP. 

More specifically, the Agency sought 

comment on whether it should adopt 

tests for FCW that were more complex 

or at higher speeds compared to those 

tests/conditions proposed for CIB 

evaluations, and if so, whether or how 

NHTSA should amend the current FCW 

performance criteria (i.e., TTCs) and/or 

test scenario specifications. 

Summary of Comments 

Intel, Honda, Auto Innovators, and 

GM recommended that the Agency not 

adopt any additional or alternative test 

scenarios or conditions for NCAP’s FCW 

assessments. GM and Auto Innovators 

asserted that adding more complicated 

tests would increase test variation 

without providing meaningful 

performance distinctions, thus 

hampering consumers’ ability to use 

results to compare performance across 

vehicles. Auto Innovators further stated 

that the current scenarios align well 

with crash data and other NCAPs. FCA 

also suggested that NHTSA retain the 

current test scenarios and did not offer 

suggested changes. 

In contrast, some respondents stated 

that the current FCW test conditions are 

not sufficient. Specifically, Adasky 

supported adopting tests for FCW (and 

CIB/DBS) that would assess system 

performance at higher speeds, at 

nighttime, and while turning. The 

commenter further stated that thermal 

cameras are currently available and can 

perform well under such conditions. 

NTSB also recommended incorporation 

of other test scenarios, including those 

involving cross traffic, vehicle cut-in 

situations, and additional targets (e.g., 

different types or orientations of 

vehicles, roadway hardware, such as 

crash attenuators, etc.).187 CAS 

encouraged the Agency to aim to 

optimize safety rather than simply 

encourage compliance. 

Response to Comments and Agency 

Decisions 

As NHTSA has decided to integrate 

FCW testing into its AEB assessments as 

part of this upgrade to NCAP, and 

commenters were generally not 

supportive of retaining separate FCW 

assessments, the Agency will not 

incorporate any additional FCW test 

scenarios or test conditions at this time. 

However, the Agency currently has 

plans to conduct research that aligns 

with some of the commenters’ 

recommendations, including nighttime 

AEB assessments and AEB testing with 

motorcycles and bicycles. NHTSA will 

continue to add scenarios to NCAP’s 

roadmap in the future as research data 

becomes available, as detailed, objective 

test procedures are drafted, and as 

technologies mature to address the 

safety need. 

b. Additional AEB Test Scenarios and 

Test Surrogates 

As mentioned previously, in its 

March 2022 RFC notice, NHTSA 

discussed findings from a 2019 IIHS 

study 188 of 2009–2016 crash data from 

23 states which suggested that the 

increasing effectiveness of AEB 

technology in certain crash situations is 

changing the rear-end crash problem. 

The study identified types of rear-end 

crashes in which striking vehicles 

involved in rear-end crashes were more 

likely to be equipped with AEB.189

These included rear-end crashes: (1) 

where the striking vehicle was turning 

relative to when it was moving straight; 

(2) when the struck vehicle was turning 

or changing lanes relative to when it 

was slowing or stopped; (3) when the 

struck vehicle was not a passenger 


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Federal Register / Vol. 89, No. 232 / Tuesday, December 3, 2024 / Notices 95975 

190Cicchino & Zuby, 2019. 

191Safety Recommendation H–20–1, currently 

classified ‘‘Open—Acceptable Response.’’ 

192According to DRI, there were 5,579 motorcycle 

fatalities in 2020 compared to 1,260 cyclist 

fatalities. 

193 IIHS data showed 4.2 million registrants in 

2002 compared to 8.3 million in 2018. 

194Safety Recommendation H–18–29, currently 

classified ‘‘Open—Acceptable Response.’’ 

195 GM cited Leslie, A.J., Kiefer, R.J., Flannagan, 

C.A., Owen, S.H, & Schoettle, B.A. (2022). Analysis 

of the Field Effectiveness of General Motors Model 

Year 2013–2020 Advanced Driver Assistance 

System Features. UMTRl–2022–2 as a source of data 

considered for its conclusion. 

vehicle or was a special use vehicle 

relative to a passenger car; (4) on snowy 

or icy roads; or (5) on roads with speed 

limits of 112.7 kph (70 mph) relative to 

those with 64.4 to 72.4 kph (40 to 45 

mph) speed limits. 

Findings from the study suggested 

that tests used to evaluate the 

performance of AEB systems by the 

Agency’s NCAP and other consumer 

information programs are influencing 

the development of countermeasures 

capable of minimizing the crash 

problems they were intended to address. 

However, the results also implied that, 

while current AEB systems are effective 

at addressing the most common rear-end 

crashes, they have not yet been 

optimized to address more atypical 

crashes where the SV is the striking 

vehicle. 

Given IIHS’s findings, NHTSA 

requested comment on if (and how) it 

should alter its current AEB tests to not 

only address the ‘‘changing’’ rear-end 

crash problem, but also discourage 

system performance degradation in 

more typical crash situations, create 

unintended safety consequences, or 

adversely affect AEB use due to 

nuisance activations. The Agency also 

sought comment on future suggestions 

for AEB generally (i.e., beyond any nearterm upgrade), including the adoption 

of additional AEB tests. 

Summary of Comments 

Capture Front Impact Events 

Rivian and NTSB stated the Agency 

should add ‘‘cut-in’’ scenarios, while 

CAS expressed that NHTSA should add 

‘‘lead vehicle maneuvers.’’ Similar to 

Rivian and CAS, and in line with 

findings from its 2019 study, IIHS 

suggested adding scenarios to capture 

lead vehicles that were changing lanes 

or turning, and tests where the lead 

vehicle is a non-passenger vehicle (e.g., 

medium- or heavy-duty truck) or 

motorcycle in order to improve the realworld effectiveness of AEB systems. 

Further, the organization suggested 

incorporating tests where the SV is 

turning (i.e., cross traffic) or travelling 

on roads with speed limits of 112.7 kph 

(70 mph) or more. IIHS explained, as the 

Agency acknowledged in its March 2022 

RFC notice, that these situations were 

over-represented in real-world rear-end 

crashes involving an AEB-equipped 

striking vehicle.190 Although the group 

acknowledged that the majority of the 

crash types mentioned were ‘‘rare,’’ 

those where an AEB-equipped vehicle 

struck a large truck or motorcycle 

accounted for approximately 40 percent 

of fatal rear-end crashes, thus suggesting 

that a test scenario simulating this crash 

type should be given thoughtful 

consideration for adoption. Adasky also 

supported AEB testing for turning 

scenarios. 

Other commenters also favored 

incorporation of certain scenarios 

recommended by IIHS. Intel, for 

example, expressed support for 

including oncoming and crossing traffic 

test scenarios, similar to those recently 

adopted by Euro NCAP. IDIADA, along 

with several public commenters, 

mentioned the need for higher-speed 

assessments. Since testing becomes 

more difficult at higher speeds, the test 

laboratory suggested the Agency should 

incorporate a requirement that AEB 

systems must be operational up to 120 

kph (74.6 mph). NTSB also favored the 

addition of cross-traffic scenarios, 

assessments for various vehicle types 

and orientations, and assessments for 

‘‘common roadway obstacles’’ like 

‘‘roadway hardware’’ (e.g., crash 

attenuators, concrete median barriers, 

etc.) that many vehicles do not currently 

detect.191

Finally, ZF Group supported adding 

an Emergency Steering Support (ESS) 

test, which it stated would assure 

vehicles provide steering (or added 

steering, in the case that the driver is 

already steering) to avoid a collision 

with the vehicle in front of it if there is 

not enough time for CIB to intervene 

effectively before a crash occurs. 

Examples of these scenarios include 

situations where vehicles are travelling 

at a high rate of speed and ‘‘scenarios 

with low overlap.’’ 

Capture Backing Events 

There were commenters, including 

TRC and Consumer Reports, who 

mentioned that the Agency should add 

rear automatic emergency braking 

(RAB). Consumer Reports suggested that 

the Agency adopt a rear cross-traffic 

warning (RCTW) test. 

Add Motorcycle or Other Powered 2- 

Wheeled Test Device 

Some commenters stated, like IIHS, 

that the Agency should adopt AEB test 

scenarios for motorcycle test devices. 

DRI proposed AEB testing with a 

motorcycle and/or scooter test device 

because: (1) ‘‘motorcycle fatalities 

reached an all-time high’’ in 2020,192 (2) 

the number of registered on-road 

motorcycles has been steadily 

increasing,193 and (3) NHTSA data 

shows that more than a quarter of 

motorcycle accidents involve rear-end 

crashes. FCW testing involving a 

motorcycle test device that was 

conducted by DRI showed that 

motorcycle detection rates varied 

widely compared to vehicle detection 

rates. The laboratory remarked that in 

many cases the SV either did not detect 

the motorcycle test device or detected it 

much later compared to the vehicle test 

device. 

NTSB also supported AEB (and FCW) 

test assessments using a motorcycle test 

device.194 Similarly, Intel suggested the 

Agency consider incorporation of the 

test device used in Euro NCAP’s 

powered two-wheeler (PTW) tests. 

Add Additional AEB Test Scenarios 

Based on Real-World Data 

Several commenters (Auto Innovators, 

BMW, FCA, and GM) specifically stated 

the Agency should not adopt any 

additional AEB test scenarios for NCAP 

unless real-world data supports their 

inclusion. FCA, GM, and Auto 

Innovators commented that current AEB 

systems have shown significant safety 

benefits in reducing rear-end crashes, 

such that according to GM and Auto 

Innovators, it is expected that adopting 

additional rear-end AEB test scenarios 

would likely offer little additional 

benefit.195 The two commenters stated 

that any additional AEB performance 

assessments should be centered around 

new crash types (depending on system 

capabilities) and supported by crash 

data trends. In addition, Auto 

Innovators asserted that potential new 

scenarios, such as those involving 

turning by an SV or lead vehicle, a lead 

vehicle lane change, or alternative test 

targets, may require vehicles to have 

cameras offering a larger field of view, 

additional radars (such as on the vehicle 

front corners), and algorithm changes to 

permit detection of the added targets. As 

such, the organization reiterated their 

opinion that crash data should dictate 

the need for these tests, which should 

be harmonized with Euro NCAP. CAS 

also mentioned that crash statistics 

should be considered when considering 

new tests for NCAP and suggested that 

market penetration of the various 


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95976 Federal Register / Vol. 89, No. 232 / Tuesday, December 3, 2024 / Notices 

196European New Car Assessment Programme 

(Euro NCAP) Test Protocol—AEB/LSS VRU 

systems, Implementation 2023. Version 4.5, 

December 2023. 

197https://www.utac.com/wp-content/uploads/ 

2023/04/MUSE-d2-1-motorcyclist-targetspecifications.pdf. 

198When published, Euro NCAP will replace the 

specifications provided with those in ISO/AWI 

19206–5, ‘‘Road vehicles—Test devices for target 

vehicles, vulnerable road users and other objects, 

for assessment of active safety functions—Part 5: 

Requirements for Powered Two-Wheeler targets’’. 

At the time of this publication, ISO/AWI 19206–5 

is Under Development in Stage 20.00 (Preparatory, 

New project registered in TC/SC work programme). 

199Swanson, E., Foderaro, F., Yanagisawa, M., 

Najm, W.G., & Azeredo, P. (2019, August), Statistics 

of light-vehicle pre-crash scenarios based on 2011– 

2015 national crash data (Report No. DOT HS 812 

745), Washington, DC: National Highway Traffic 

Safety Administration. 

system types (e.g., camera, radar) should 

guide priority for future testing. 

MEMA did not offer explicit 

suggestions for NHTSA to consider with 

respect to additional test scenarios that 

may be viable for inclusion, but the 

commenter did express support for the 

Agency’s decision to ‘‘focus resources 

on emerging trends with the potential 

for future updates as the crash problem 

evolves.’’ NTSB recommended that the 

Agency add tests (for all technologies) 

that assess higher speeds and increased 

complexities to evaluate ‘‘advanced 

capabilities.’’ State Farm and NYC DOT/ 

NYC DCAS, Vision Zero Task Force also 

expressed support for higher test speeds 

in general and tests to reflect real-world 

driving conditions and crashes. 

Response to Comments and Agency 

Decisions 

Capture Front Impact Events 

While the LVS, LVM, and LVD 

scenarios cover a substantial number of 

frontal impact events, there are other 

frontal impact scenarios that will not be 

directly assessed by NHTSA’s NCAP 

testing as adopted in this final notice. 

Several commenters to the March 

2022 RFC requested the addition of 

various intersection crash scenarios. 

The Agency agrees that, while the 

scenarios adopted for NCAP’s AEB 

testing cover a large portion of crashes, 

there is a safety need for scenarios 

which cover intersection-specific 

interactions, such as left turn across 

path and straight crossing path 

conditions. As mentioned in the NCAP 

Roadmap section, NHTSA plans to 

consider the inclusion of these scenarios 

in the future. Pending necessary 

research, the Agency may implement 

these additional scenarios for model 

year 2032 vehicles. 

Regarding AEB testing at higher 

speeds, NHTSA acknowledges that there 

is further safety potential to be realized 

by assessing CIB and DBS performance 

at speeds greater than those adopted for 

NCAP in this final notice. Indeed, 

NHTSA is aware, from a review of 

owner’s manuals, that many vehicle 

manufacturers have equipped their 

vehicles with AEB systems that function 

at speeds much higher than those which 

will be evaluated by NCAP. Given the 

practical limitations of testing (e.g., 

safety of test personnel, vehicle and test 

equipment damage, etc.), test speeds are 

currently restricted. That said, the 

Agency expects that, with further 

evolution of test methods, vehicle 

systems, and equipment, test speeds 

could be increased in the future. The 

NCAP Roadmap currently incorporates 

a plan for further enhancement to the 

adopted AEB tests with evaluations 

beginning with model year 2033 

vehicles. 

At this time, NHTSA is not 

incorporating ESS testing as ZF Group 

suggested. The Agency must further 

study the capabilities and limitations of 

systems meant to support the driver 

during these maneuvers prior to 

incorporating assessments in its NCAP 

testing. The Agency may decide to 

include an evaluation of ESS systems in 

the future, particularly if it moves to 

evaluating performance at higher speeds 

than those adopted in this final decision 

notice. 

Additional recommendations 

included assessments using a variety of 

other objects as targets, such as crash 

attenuators, median barriers, and other 

roadway hardware. Large trucks were 

also proposed as possible impact targets 

for AEB evaluation. NHTSA does not 

have current research planned to 

evaluate these scenarios, but it may 

consider these, and other, assessments 

for the future. 

Capture Backing Events 

The Agency will not include backing 

scenarios, such as those mitigated by 

RAB or RCTW, in NCAP’s AEB testing 

at this time. As noted in the March 2022 

notice, NHTSA is currently amending 

its RAB test procedure to account for 

earlier comments received. Once this 

work is completed, NHTSA hopes to 

add the related assessments to NCAP. 

As noted in the NCAP Roadmap section, 

NHTSA’s plan is to evaluate RAB 

systems starting with model year 2028 

vehicles. 

Add Motorcycle or Other Powered 2- 

Wheeled Target 

In the March 2022 RFC notice, 

NHTSA stated that it was conducting 

additional research to evaluate vehicle 

AEB performance when approaching 

cyclists and motorcyclists. The Agency 

acknowledges, as did DRI, that 

motorcyclist fatalities have risen in 

recent years. Euro NCAP performs carto-motorcyclist AEB testing under its 

AEB/Lane Support System (LSS) VRU 

Test Protocol.196 Specifications for the 

motorcyclist test device used in Euro 

NCAP’s testing can be found in 

Motorbike Users Safety Enhancement 

(MUSE) Deliverable 2.1, Motorcyclist 

Target Specifications.197 198 The test 

device represents an average human 

adult motorcyclist on a motorcycle with 

dimensions based on average values of 

most registered motorcycles in Europe 

with a cylinder capacity of greater than 

500 cc. Euro NCAP’s AEB testing 

includes several scenarios, including 

rear stationary, rear braking, and front 

turn across path scenarios, all in 

daylight conditions. 

Preliminary results of NHTSA’s 

motorcycle research testing using five 

vehicles have shown that many factors, 

such as lane position of the test device, 

lighting condition, and speed may 

influence vehicle braking performance, 

and there was no discernable pattern 

across the five vehicles tested. Further, 

some concerns were noted with the 

motorcyclist surrogate design used. 

Thus, NHTSA has further research 

underway and planned. A report 

summarizing this initial research, which 

was conducted in both daylight and 

darkness conditions, is expected to be 

available in 2024. 

NHTSA has expedited its follow-on 

research on AEB for other VRUs, namely 

bicyclists and motorcyclists. The 

Agency’s research to develop and 

evaluate test procedures and surrogate 

targets for certain crash scenarios to 

address bicyclist and motorcyclist 

injuries in crashes with light vehicles is 

expected to be completed in 2024. As 

noted in the mid-term updates to NCAP 

in the NCAP roadmap finalized in this 

notice, NHTSA has included evaluation 

of AEB for mitigating crashes with 

bicyclists and motorcyclists starting 

with model year 2028 vehicles. 

c. Additional AEB Environmental Test 

Conditions 

In its March 2022 RFC notice, NHTSA 

noted that 51 percent of fatalities and 80 

percent of MAIS 1–5 injuries caused by 

rear-end crashes occurred under 

daylight conditions. Further, nearly 92 

percent of fatalities and 88 percent of 

injuries caused by such crashes 

occurred in clear weather.199 However, 

IIHS’s rear-end crash study concluded 

that AEB-equipped vehicles are overrepresented for crashes occurring in 

certain weather conditions, such as 


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Federal Register / Vol. 89, No. 232 / Tuesday, December 3, 2024 / Notices 95977 

200Cicchino, J.B. & Zuby, D.S. (2019, August), 

Characteristics of rear-end crashes involving 

passenger vehicles with automatic emergency 

braking, Traffic Injury Prevention. 2019, VOL. 20, 

NO. S1, S112–S118, https://doi.org/10.1080/ 

15389588.2019.1576172. 

201 ‘‘Low visibility.’’ Low Visibility—FHWA Road 

Weather Management. https://ops.fhwa.dot.gov/ 

weather/weather_events/low_visibility.htm. 

snow and ice.200 Given these findings 

and the fact that the Agency’s proposal 

for PAEB systems encompassed testing 

under less-than-ideal environmental 

conditions (specifically in darkness), 

NHTSA sought comment on whether it 

should pursue research to assess AEB 

system performance under less-thanideal environmental conditions, and if 

so, what environmental conditions 

would be appropriate. This research 

would subsequently inform further 

updates to NCAP testing. 

Summary of Comments 

Commenters were generally in favor 

of the Agency conducting research to 

support inclusion of evaluations for 

different environmental conditions to 

encourage improved AEB performance. 

However, responses were varied, with 

suggestions spanning lighting 

conditions, road surface conditions, 

atmospheric conditions, etc. There were 

also a few commenters who did not 

support additional research into 

alternative environmental test 

conditions. 

Lighting Conditions 

Several respondents, including ASC, 

Rivian, State Farm, and TRC, suggested 

that NHTSA add test scenarios that 

include different lighting conditions. 

ASC, CAS, Consumer Reports, and 

Uhnder favored assessments for dark, 

nighttime conditions as well as 

conditions that may cause glare or 

temporary driver blindness, such as 

those resulting from travelling directly 

toward the sun at dawn or dusk. 

Bosch, Adasky, and The Lidar 

Coalition commented that they support 

testing in low light conditions. Similar 

assertions were expressed by public 

commenters who mentioned that 

current AEB systems are problematic 

because they do not perform well in low 

light. The Lidar Coalition commented 

that testing in low light (with no 

overhead lighting and use of only the 

lower beam headlamps) is necessary 

because of performance differences 

observed for various sensor types. The 

commenter asserted that: cameras have 

high resolution but do not work well 

(i.e., cannot ‘‘see’’) in low light 

conditions; radar works well (i.e., can 

‘‘see’’) in such conditions but lacks the 

resolution to detect slow-moving or 

stationary objects and to distinguish 

between objects that are close together; 

and lidar can both ‘‘see’’ in low light 

conditions and has high resolution, thus 

affording advantages where the other 

sensors independently cannot. Adasky 

stated that thermal cameras can perform 

well in dark conditions. 

Although Auto Innovators, in general, 

did not support the consideration of 

alternative environmental conditions to 

assess AEB systems currently, they did 

express modest support for adding low 

light evaluations in the near-term. 

However, the group, in addition to TRC, 

cautioned that the GVT would likely 

have to be modified to permit taillight 

illumination (TRC) and ‘‘replicate the 

vehicle lighting or light reflection 

characteristics of real vehicles at night’’ 

(Auto Innovators). 

Road Surface Conditions 

Other commenters, including Rivian 

and CAS, recommended the Agency add 

test scenarios that evaluate performance 

on wet surfaces. CAS and Consumer 

Reports stated that assessments for icy 

conditions may also be appropriate, and 

IIHS suggested adding evaluations for 

‘‘surfaces with reduced friction.’’ IIHS 

stated that crash data shows that AEBequipped vehicles are over-represented 

in rear-end crashes on ‘‘slippery roads’’ 

such that encouraging AEB systems 

through testing to adjust brake force and 

intervene earlier on slippery roads 

compared to dry roads should promote 

improved AEB performance in the real 

world. IIHS further mentioned that their 

testing has shown that ‘‘AEB systems 

initiate automated braking with the 

same force and time on ‘slippery’ roads 

as on snowy roads,’’ suggesting that 

only one test condition would be 

necessary. Advocates also supported 

incorporating testing for various 

roadway conditions. 

Atmospheric Conditions 

Other respondents encouraged 

pursuing research to assess AEB 

performance in various atmospheric 

conditions that cause reduced driver 

visibility such as fog, smoke, ash, rain, 

hail, and snow (ASC and Uhnder). 

Uhnder remarked that fog alone causes 

more than 600 fatalities and over 16,300 

injuries per year in the U.S.201 and yet 

digital radar, which is ‘‘agnostic to 

lighting conditions’’ and functions in 

‘‘degraded visibility environments,’’ is 

available and could provide safety 

benefits. 

Honda stated that NHTSA should first 

test in ‘‘normal’’ rain followed by fog, 

‘‘heavy’’ rain, and snow. Although the 

automaker acknowledged that AEB 

performance may be limited in heavy 

rain and snow conditions due to tire 

traction, the company stated that 

assuring effective AEB functionality in 

conditions representing ‘‘normal’’ rain 

was reasonable and appropriate. State 

Farm also supported testing in snow 

and over a range of fog and rain 

conditions since sensors are known to 

operate differently. Likewise, Consumer 

Reports supported testing in heavy rain 

and snow as well as in low-visibility 

conditions, such as those found in fog 

and smoke, and Adasky supported 

assessments for heavy rain, snow, fog, 

and sleet. Adasky asserted that such 

conditions are ‘‘typical and 

predictable;’’ therefore, AEB systems 

should function reliably. Conversely, 

Auto Innovators explicitly stated that 

they did not support testing in heavy 

rain and snow because of the loss of tire 

traction previously mentioned by 

Honda. 

Several public commenters also 

expressed support for testing in 

inclement weather in general, stating 

current AEB systems are less reliable in 

such conditions. Additionally, 

Advocates stated that evaluating system 

performance under different weather 

and temperature conditions seems 

appropriate, since these are normal 

vehicle operating conditions. The group 

also stated that this testing will be 

essential to address inadequacies in 

system performance to assure the 

success of automated vehicles (AVs), as 

many of these technologies will serve as 

the building blocks for future AV 

development. Advocates, along with 

The League, suggested that NHTSA 

adopt those conditions that prove to be 

the most ‘‘problematic’’ for technologies 

during Agency research. 

Use Real-World Data 

BMW, FCA, Auto Innovators, and GM 

stated that NHTSA should use realworld crash data to guide development 

of future test conditions. 

With respect to environmental 

conditions, Auto Innovators asserted 

that, if the Agency decides to pursue 

future research to assess AEB 

performance for varying environmental 

conditions, it should prioritize those 

conditions that occur more frequently in 

the real world before proceeding with 

assessments that simulate less 

frequently encountered conditions. The 

group cautioned that, at this time, the 

Agency should add only those 

conditions that are justifiable (i.e., will 

result in large safety benefits) because 

adding ‘‘complex . . . variations in 

environmental conditions may require 

more sophisticated sensors and/or 

research and development that can 


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95978 Federal Register / Vol. 89, No. 232 / Tuesday, December 3, 2024 / Notices 

202National Center for Statistics and Analysis. 

(2023, June), Pedestrians. (Traffic Safety Facts, 2021 

Data. Report No. DOT HS 813 458), Washington, 

DC: National Highway Traffic Safety 

Administration. 

203 Kullgren, A., Amin, K, & Tingvall, C. (2023) 

Effects on crash risk of automatic emergency 

braking systems for pedestrians and bicyclists, 

Traffic Injury Prevention, 24:sup1, S111–S115, DOI: 

10.1080/15389588.2022.2131403. 

204Carpenter, M.G., Moury, M.T., Skvarce, J.R., 

Struck, M. Zwicky, T.D., & Kiger, S.M. (2014, June), 

Objective tests for forward looking pedestrian crash 

avoidance/mitigation systems: Final report (Report 

No. DOT HS 812 040), Washington, DC: National 

Highway Traffic Safety Administration. 

205 Yanagisawa, M., Swanson, E., Azeredo, P., & 

Najm, W.G. (2017, April). Estimation of potential 

safety benefits for pedestrian crash avoidance/ 

mitigation systems. (Report No. DOT HS 812 400). 

Washington, DC: National Highway Traffic Safety 

Administration. 

206 84 FR 64405 (Nov. 21, 2019). 

207Overlap is defined as the percent of the 

vehicle’s width that the pedestrian would traverse 

prior to impact if the vehicle’s speed and 

pedestrian’s speed remain constant. 

ultimately affect affordability.’’ 

Likewise, BMW added that NHTSA 

should consider incorporating those 

environmental conditions that 

contribute to a higher percentage of 

accidents, critical injuries, and fatalities. 

That said, the manufacturer also stated 

they were not currently aware of any 

environmental condition that would be 

appropriate for inclusion. Similarly, GM 

remarked that real-world data shows 

that for those crashes with the highest 

Functional Years Lost that are relevant 

to the ADAS technologies the Agency is 

considering adopting in NCAP, the 

environmental conditions were 

typically clear and dry, such that there 

is not a strong need to include 

alternative assessments. 

Repeatability and Reproducibility 

Concerns 

Several commenters (Auto Innovators, 

Bosch, GM, Intel, and TRC) cautioned 

NHTSA that repeatability and 

reproducibility is a concern for 

assessments involving environmental 

conditions. In fact, Intel, GM, and Auto 

Innovators stated they did not support 

the inclusion of less-than-ideal 

environmental conditions in NCAP 

assessments for this reason. GM added 

that testing additional environmental 

conditions would be ‘‘inherently 

difficult and expensive to precisely 

control,’’ and Auto Innovators stated 

that, except for possible low light 

conditions, it would add ‘‘unnecessary 

test complexity.’’ Both commenters 

further stated that the limited 

assessments conducted by NCAP would 

pale in comparison to the vast range of 

conditions and overall performance 

considerations that must be factored in 

during product design and 

development. 

Add Changes to Test Conditions to 

NCAP Roadmap 

Some commenters (Auto Innovators, 

BMW, Bosch, and Consumer Reports) 

requested that NHTSA include any 

planned research into environmental 

conditions, along with expected 

completion dates, in the NCAP roadmap 

so that industry would have time to 

prepare for such changes. 

Response to Comments and Agency 

Decisions 

At the moment, the Agency has 

decided to continue its research on AEB 

technologies. Further enhancements to 

AEB with additional scenarios and test 

conditions will be considered in the 

long-term updates to NCAP for the 

period 2029 to 2033. 

V. Adding Pedestrian Automatic 

Emergency Braking (PAEB) Technology 

NHTSA is committed to improving 

the safety of VRUs and acknowledges 

the rapidly growing safety risk to 

pedestrians, with 7,388 pedestrians 

killed in 2021 and 60,577 injured in 

traffic crashes in the U.S.202 NHTSA 

notes that between 2012 and 2021, 

pedestrian fatalities rose from 14 to 17 

percent of all traffic fatalities. From 

2020 to 2021 alone, pedestrian fatalities 

increased 13 percent, and pedestrian 

injuries increased 11 percent. PAEB has 

the potential to mitigate this risk, with 

a recent Swedish study finding that in 

daylight and twilight conditions, the 

presence of PAEB reduced pedestrian 

crash risk by 18 percent.203 Given this 

substantial safety need, NHTSA is 

adopting PAEB evaluation as part of this 

NCAP upgrade. 

By way of background, PAEB systems 

function like AEB systems but detect 

pedestrians instead of vehicles. PAEB 

systems use information from forwardlooking sensors to warn the driver and 

actively apply the vehicle’s brakes when 

a pedestrian (or, sometimes, cyclist, 

scooter-rider, motorcyclist) is in the 

path of the vehicle and the driver has 

not acted to avoid the crash. Current 

PAEB systems typically use cameras to 

determine whether a pedestrian is in 

imminent danger of being struck by the 

vehicle. However, some systems use a 

combination of cameras, radars, and/or 

possibly lidar sensors. 

A. Proposed Pedestrian Automatic 

Emergency Braking Test Procedures 

Most pedestrian crashes occur when a 

pedestrian is in the forward path of a 

driver’s vehicle. Four common 

pedestrian crash scenarios include 

when the vehicle is: 

1. Heading straight and a pedestrian is 

crossing the road; 

2. Turning right and a pedestrian is 

crossing the road; 

3. Turning left and a pedestrian is 

crossing the road; and 

4. Heading straight and a pedestrian is 

walking along or against traffic. 

These four crash scenarios are defined 

as Scenarios S1–S4, respectively, by the 

Crash Avoidance Metrics Partnership 

(CAMP) Crash Imminent Braking (CIB) 

Consortium.204

NHTSA’s draft research PAEB test 

procedure, published on November 21, 

2019, and referenced herein as the 2019 

PAEB test procedure, included two 

scenarios, S1 and S4, which were 

identified when combined as the two 

most frequent, injurious, and fatal crash 

scenarios involving pedestrians in the 

U.S.205 206 Scenario S1 represents a 

pedestrian crossing the road in front of 

the vehicle, and the S4 scenario 

represents a pedestrian moving with or 

against traffic along the side of the road 

in the path of the vehicle. Both test 

scenarios are expanded into multiple 

test conditions representing multiple 

pedestrian impact locations. A short 

description of each test condition (e.g., 

S1a, S4b) described in the 2019 PAEB 

test procedure is presented below for 

each test scenario (S1 and S4): 

• S1 

Æ S1a—The SV travels in a straight, 

forward direction at 16 kph (9.9 mph) 

or 40 kph (24.9 mph). An adult 

pedestrian mannequin crosses 

perpendicular to the vehicle’s line of 

travel at 5 kph (3.1 mph). The SV 

encounters the mannequin walking 

from the right (i.e., the passenger’s 

side of the vehicle) with 25 percent 

overlap of the vehicle.207 See Figure 

7(a) for a scenario diagram. 

Æ S1b—The SV travels in a straight, 

forward direction at 16 kph (9.9 mph) 

or 40 kph (24.9 mph). An adult 

pedestrian mannequin crosses 

perpendicular to the vehicle’s line of 

travel at 5 kph (3.1 mph). The SV 

encounters the mannequin walking 

from the right with 50 percent overlap 

of the vehicle. See Figure 7(b) for a 

scenario diagram. 

Æ S1c—The SV travels in a straight, 

forward direction at 16 kph (9.9 mph) 

or 40 kph (24.9 mph). An adult 

pedestrian mannequin crosses 

perpendicular to the vehicle’s line of 

travel at 5 kph (3.1 mph). The SV 

encounters the mannequin walking 

from the right with 75 percent overlap 


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Federal Register / Vol. 89, No. 232 / Tuesday, December 3, 2024 / Notices 95979 

of the vehicle. See Figure 7(c) for a 

diagram. 

Æ S1d—The SV travels in a straight, 

forward direction at 16 kph (9.9 mph) 

or 40 kph (24.9 mph). A child 

pedestrian mannequin crosses 

perpendicular to the vehicle’s line of 

travel at 5 kph (3.1 mph). The SV 

encounters the child mannequin 

running from behind parked cars on 

the right with 50 percent overlap of 

the vehicle. See Figure 8 for a 

diagram. 


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Figure 7: Adult Pedestrian Crossing Path Conditions Sla (a), Slb (b), and Slc (c) 
95980 Federal Register / Vol. 89, No. 232 / Tuesday, December 3, 2024 / Notices 

Æ S1e—The SV travels in a straight, 

forward direction at 40 kph (24.9 

mph). An adult pedestrian mannequin 

crosses perpendicular to the vehicle’s 

line of travel at 8 kph (5.0 mph). The 

SV encounters the mannequin 

walking from the left (i.e., the driver’s 

side of the vehicle) with 50 percent 

overlap of the vehicle. See Figure 9 

for a diagram. 


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Federal Register / Vol. 89, No. 232 / Tuesday, December 3, 2024 / Notices 95981 

Æ S1f—The SV travels in a straight, 

forward direction at 40 kph (24.9 

mph). An adult pedestrian mannequin 

moves perpendicular to the vehicle’s 

line of travel toward the vehicle’s 

right at 5 kph (3.1 mph), but it stops 

short (¥25 percent overlap) of the 

SV’s path. See Figure 10(a) for a 

diagram. 

Æ S1g—The SV travels in a straight, 

forward direction at 40 kph (24.9 

mph). An adult pedestrian mannequin 

crosses perpendicular to the vehicle’s 

line of travel toward the vehicle’s 

right at 5 kph (3.1 mph). The 

mannequin clears the SV’s path (125 

percent overlap). See Figure 10(b) for 

a diagram. 

• S4 

Æ S4a—The SV travels in a straight, 

forward direction at 16 kph (9.9 mph) 

or 40 kph (24.9 mph). An adult 

pedestrian mannequin is stationary in 

front of the SV at 25 percent overlap. 

The mannequin is facing away from 

the SV on the right hand side of the 

road. See Figure 11 for a diagram. 

Æ S4b—The SV travels in a straight, 

forward direction at 16 kph (9.9 mph) 

or 40 kph (24.9 mph). An adult 

pedestrian mannequin is stationary in 

front of the SV at 25 percent overlap. 

The mannequin is facing toward the 

SV on the right hand side of the road. 

See Figure 11 for a diagram. 


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Figure 10: Adult Pedestrian False Positive Crossing Path Conditions SJ/ (a) and Slg (b) 
95982 Federal Register / Vol. 89, No. 232 / Tuesday, December 3, 2024 / Notices 

Æ S4c—The SV travels in a straight, 

forward direction at 40 kph (24.9 

mph). An adult pedestrian mannequin 

is walking away from the approaching 

SV at 5 kph (3.1 mph), parallel to the 

flow of traffic. The mannequin is 

located on the right hand side of the 

road at 25 percent overlap. See Figure 

12 for a diagram. 


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from SV) and S4b (Pedestrian Facing Toward SV) 

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Figure 12: Adult Pedestrian Moving In-Path Condition S4c 
Federal Register / Vol. 89, No. 232 / Tuesday, December 3, 2024 / Notices 95983 

208 Yanagisawa, M., Swanson, E., Azeredo, P., & 

Najm, W.G. (2017, April), Estimation of potential 

safety benefits for pedestrian crash avoidance/ 

mitigation systems (Report No. DOT HS 812 400), 

Washington, DC: National Highway Traffic Safety 

Administration. 

209 Yanagisawa, M., Swanson, E., Azeredo, P., & 

Najm, W.G. (2017, April), Estimation of potential 

safety benefits for pedestrian crash avoidance/ 

mitigation systems (Report No. DOT HS 812 400), 

Washington, DC: National Highway Traffic Safety 

Administration. 

210Ferenchak, Nicholas N., Gutierrez, Risa E., & 

Singleton, Patrick A. (2022), Shedding light on the 

pedestrian safety crisis: An analysis across the 

injury severity spectrum by lighting condition, 

Traffic Injury Prevention, 23:7, 434–439, DOI: 

10.1080/15389588.2022.2100362. 

211https://www.nsc.org/road/safety-topics/ 

driving-at-night. 

212https://www.nhtsa.gov/sites/nhtsa.gov/files/ 

808707.pdf. 

213https://deepblue.lib.umich.edu/bitstream/ 

handle/2027.42/58726/99831.pdf?sequence=1&is

Allowed=y. 

214Cicchino, J.B (2022, February), Effects of 

automatic emergency braking systems on 

pedestrian crash risk, Insurance Institute for 

Highway Safety, https://www.iihs.org/api/ 

datastoredocument/bibliography/2243. 

The proposed 2019 PAEB test 

procedure required that all testing take 

place during daylight hours with good 

atmospheric visibility and the use of 

posable pedestrian mannequins. 

As detailed in the March 2022 RFC 

Notice, the Agency proposed several 

changes to the 2019 PAEB test 

procedure involving the pedestrian 

mannequins, test conditions, test 

variants for SV speed, specified lighting 

conditions, and the number of test trials 

required to be conducted for each test 

variant. The RFC included the 

following: 

1. Use of articulated pedestrian 

mannequins with moving legs, instead 

of the posable child and adult 

pedestrian mannequins; 

2. SV test speeds from 10 kph (6.2 

mph) to 60 kph (37.3 mph) in 

increments of 10 kph (6.2 mph) for each 

test condition (S1a, S1b, S1c, S1d, S1e, 

S4a, S4b, and S4c) 

3. PAEB evaluation in darkness 

lighting conditions with the vehicle’s 

lower beam headlamps switched on, in 

addition to daylight conditions. 

The test matrix of the proposed PAEB 

evaluations is summarized in Table 17. 

TABLE 17—TEST MATRIX OF PROPOSED PAEB EVALUATIONS IN THE MARCH 2022 RFC NOTICE

Test 

cond. Size 

Test speeds (kph (mph)) Movement 

classification Path origin Overlap (%) Obstruction Light condition 

SV Pedestrian 

S1a ...... Adult ............... 10, 20, 30, 40, 50, 60 (6.2, 

12.4, 18.6, 24.9, 31.1, 37.3).

5 (3.1) Walk ............... Right ............... 25 No ................. Daylight 

Darkness—Lower Beam. 

S1b ...... Adult ............... 10, 20, 30, 40, 50, 60 (6.2, 

12.4, 18.6, 24.9, 31.1, 37.3).

5 (3.1) Walk ............... Right ............... 50 No ................. Daylight 

Darkness—Lower Beam. 

S1c ...... Adult ............... 10, 20, 30, 40, 50, 60 (6.2, 

12.4, 18.6, 24.9, 31.1, 37.3).

5 (3.1) Walk ............... Right ............... 75 No ................. Daylight 

Darkness—Lower Beam. 

S1d ...... Child ............... 10, 20, 30, 40, 50, 60 (6.2, 

12.4, 18.6, 24.9, 31.1, 37.3).

5 (3.1) Run ................. Right ............... 50 Yes ............... Daylight 

Darkness—Lower Beam. 

S1e ...... Adult ............... 10, 20, 30, 40, 50, 60 (6.2, 

12.4, 18.6, 24.9, 31.1, 37.3).

8 (5.0) Run ................. Left ................. 50 No ................. Daylight 

Darkness—Lower Beam. 

S4a ...... Adult (Facing 

Away).

10, 20, 30, 40, 50, 60 (6.2, 

12.4, 18.6, 24.9, 31.1, 37.3).

0 Stationary ....... Right ............... 25 No ................. Daylight 

Darkness—Lower Beam. 

S4b ...... Adult (Facing 

Toward).

10, 20, 30, 40, 50, 60 (6.2, 

12.4, 18.6, 24.9, 31.1, 37.3).

0 Stationary ....... Right ............... 25 No ................. Daylight 

Darkness—Lower Beam. 

S4c ...... Adult (Facing 

Away).

10, 20, 30, 40, 50, 60 (6.2, 

12.4, 18.6, 24.9, 31.1, 37.3).

5 (3.1) Walk ............... Right ............... 25 No ................. Daylight 

Darkness—Lower Beam. 

B. Linking Proposed PAEB Test 

Scenarios With Real-World Crashes 

A review of pedestrian crashes from 

the 2011–2012 GES and FARS data sets 

where a light vehicle’s front struck the 

pedestrian as the first event and there 

was no avoidance maneuver 208 found 

that, on average, the S1 and S4 pre-crash 

scenarios represent approximately 

10,431 (17 percent) of the 62,917 realworld crashes involving pedestrians 

annually. The two pre-crash scenarios 

also account for 3,889 (30 percent) of 

the 13,058 MAIS 2+ and 2,739 (40 

percent) of the 6,770 MAIS 3+ injured 

pedestrians. In these real-world crashes 

represented by S1 and S4 scenarios, 

there were, on average, 2,016 fatal 

vehicle-to-pedestrian crashes annually, 

representing 60 percent of the 3,337 

fatal vehicle-pedestrian crashes. 

More specifically, the researchers 

from the study found that for the S1 

scenario, approximately 7,481 (12 

percent) and 1,396 (42 percent) realworld crashes involving pedestrian 

injuries and fatalities occurred annually, 

respectively. These resulted in, on 

average, 2,682 (21 percent) of MAIS 2+ 

injured pedestrians and 1,879 (28 

percent) of MAIS 3+ injured pedestrians 

yearly. For the S4 scenario, 

approximately 2,950 (5 percent) and 620 

(19 percent) of real-world crashes 

involving pedestrian injuries and 

fatalities occurred annually, 

respectively. These resulted in, on 

average, 1,207 (9 percent) of MAIS 2+ 

injured pedestrians and 860 (13 percent) 

of MAIS 3+ injured pedestrians yearly. 

The above figures include both 

daytime and nighttime crashes. Though 

the 2019 PAEB test procedure specified 

daylight conditions, there is a 

demonstrated safety need for the 

Agency and industry to jointly address 

nighttime pedestrian crashes in addition 

to those crashes that occur in the 

daytime. The Volpe study of 2011–2015 

FARS and GES crash data showed that 

75 percent of pedestrian fatalities and 

38 percent of pedestrian injuries 

occurred in dark conditions, including 

darkness illuminated by overhead 

lighting.209 A study of California, North 

Carolina, and Texas crash data revealed 

that pedestrians struck in the dark were 

five times more likely to be killed than 

those struck during the day.210 Various 

factors make low-light driving 

inherently more dangerous for 

pedestrians than driving during daylight 

hours, including a reduction in 

pedestrian visibility, night vision 

deterioration as an individual ages,211

an increased likelihood of driver 

drowsiness at nighttime,212 and an 

increased likelihood that both 

pedestrians and drivers are under the 

influence of drugs or alcohol in 

darkness compared to daylight.213

Furthermore, both IIHS and AAA have 

shown performance issues with current 

PAEB systems in dark conditions.214

With regard to SV speeds, a review of 

2011–2015 FARS and GES crash data 

sets showed that, for crashes where 

posted speed limit was known, 8 

percent of pedestrian fatalities and 36 

percent of pedestrian injuries resulted 

from crashes that occurred on roadways 

with posted speeds of 40.2 kph (25 

mph) and less (i.e., at speeds equivalent 


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95984 Federal Register / Vol. 89, No. 232 / Tuesday, December 3, 2024 / Notices 

215Swanson, E., Foderaro, F., Yanagisawa, M., 

Najm, W.G., & Azeredo, P. (2019, August), Statistics 

of light-vehicle pre-crash scenarios based on 2011– 

2015 national crash data (Report No. DOT HS 812 

745), Washington, DC: National Highway Traffic 

Safety Administration. 

216The posted speed limit was either not reported 

or was unknown in 4 percent of fatal pedestrian 

crashes and 29 percent of pedestrian crashes that 

resulted in injuries. 

217Swanson, E., Foderaro, F., Yanagisawa, M., 

Najm, W.G., & Azeredo, P. (2019, August), Statistics 

of light-vehicle pre-crash scenarios based on 2011– 

2015 national crash data (Report No. DOT HS 812 

745), Washington, DC: National Highway Traffic 

Safety Administration. 

218 In 4 percent of fatal and 11 percent of 

injurious pedestrian crashes, it was unknown or not 

reported whether speeding was a factor. 

219 IIHS’s vehicle-to-pedestrian rating is a pointsbased assessment. A maximum of six points is 

possible, and points are assigned based on average 

amount of speed reduction afforded in each of three 

test scenarios, with bonus points awarded for 

vehicles that warn a driver at least 2.1 seconds prior 

to impact in a test condition similar to NHTSA’s 

S1a. 

220https://iihs.org/ratings/. 

221These test speeds represent the maximum test 

speeds potentially utilized for a given test 

condition. The actual speeds used for a given 

vehicle and test condition depended on observed 

PAEB system performance. 

222See Docket No. NHTSA–2021–0002–0002. 

There are embedded reports titled, ‘‘PEDESTRIAN 

AUTOMATIC EMERGENCY BRAKING SYSTEM 

RESEARCH TEST’’ for each of the 11 vehicle make/ 

models. 

223Cicchino, J.B (2022, February), Effects of 

automatic emergency braking systems on 

pedestrian crash risk, Insurance Institute for 

Highway Safety, https://www.iihs.org/api/ 

datastoredocument/bibliography/2243. 

224National Highway Traffic Safety 

Administration (2023, March). 2022 Light Vehicle 

Pedestrian Automatic Emergency Braking Test 

Summary. Washington, DC: National Highway 

Traffic Safety Administration. 

to those covered by NHTSA’s 2019 

PAEB test procedure), whereas 38 

percent of fatalities and 76 percent of 

injuries occurred as a result of crashes 

on roadways with posted speeds of 56.3 

kph (35 mph) and less.215 216 By 

adopting a higher maximum test speed 

than the one in the 2019 draft PAEB 

procedure, the Agency could address an 

additional 30 percent of fatalities and 40 

percent of injuries. Since speeding was 

a reported factor in only 5 percent of the 

fatal pedestrian crashes and 2 percent of 

the injurious pedestrian crashes, 

NHTSA reasoned that the posted speed 

may correlate closely with the travel 

speed of the vehicle prior to impact 

with the pedestrian.217 218

Finally, roadway alignment and grade 

for real-world pedestrian crashes in 

Volpe’s 2011–2015 data set were found 

to be comparable to those prescribed in 

the Agency’s 2019 PAEB test 

procedures. Of those pedestrian crashes 

where roadway alignment was known, 

94 percent of both fatal and injurious 

crashes occurred on a straight roadway, 

and 84 percent and 88 percent of fatal 

and injurious pedestrian crashes, 

respectively, occurred on a level 

roadway. 

C. PAEB Installation Rates and Research 

Tests 

1. PAEB Installation Rates 

New vehicles equipped with PAEB 

systems, like those equipped with AEB 

systems, are currently broadly available. 

In the five years between model years 

2018 and 2023, the percentage of the 

fleet fitted with standard PAEB systems 

rose from 19 percent to 91 percent. Not 

only has the presence of PAEB 

increased, but system performance has 

improved substantially. In model year 

2019, 21 percent of vehicles tested by 

IIHS for PAEB performance received a 

‘‘Superior’’ score, 27 percent received 

‘‘Advanced,’’ 5 percent received 

‘‘Basic,’’ and 4 percent received no 

credit. The remaining 44 percent did not 

have the technology available. By 

contrast, in model year 2022, only 12 

percent of vehicles did not have PAEB 

available; 54 percent received 

‘‘Superior’’ ratings and 30 percent 

received ‘‘Advanced’’ ratings.219 220 The 

Agency has observed similar 

improvements in PAEB performance 

over this period during its research 

testing, as discussed in the sections to 

follow. 

2. Model Year 2019 and 2020 Research 

Testing 

As described in the March 2022 RFC 

notice, the Agency conducted a series of 

tests on the same 11 model year 2019 

and 2020 vehicles used in the CIB 

testing series to assess the operational 

range and performance of then-current 

PAEB systems. For the purpose of this 

study, the Agency used the 2019 PAEB 

test procedure but employed the 

articulating mannequins in lieu of 

posable mannequins and expanded the 

test procedure specifications to include 

higher vehicle test speeds of 60 kph 

(37.2 mph) for the S1b, S1d, and S1e 

test conditions and 80 kph (49.7 mph) 

for the S4a and S4c conditions.221 For 

each test, the SV speed was 

incrementally increased to identify 

when each SV reached its operational 

limits and did not respond to the 

pedestrian mannequin. When no or late 

intervention occurred for a vehicle and 

test condition (i.e., combination of test 

scenario and speed), NHTSA repeated 

the test condition at a test speed that 

was 5 kph (3.1 mph) lower. This 

reduced speed defined the system’s 

upper capabilities. NHTSA also chose to 

alter the lighting conditions from the 

2019 PAEB test procedure specifications 

and conducted tests in both daylight 

and dark conditions using the vehicles’ 

lower or upper beam headlamps as the 

only light source to illuminate the 

pedestrian mannequin. For most of the 

darkness tests, no overhead ambient 

light source was provided in either 

condition; however, for two of the 

model year 2020 vehicles, limited 

testing was also conducted using the 

vehicles’ lower beam headlamps and 

overhead lights to investigate possible 

performance differences when using 

overhead lighting. These vehicles were 

subjected to PAEB conditions S1b, S1d, 

S1e, S4a, and S4c at test speeds of 16 

kph (9.9 mph) and 40 kph (24.9 mph). 

The Agency’s characterization testing 

showed that many model year 2019 and 

2020 vehicles were able to repeatedly 

avoid impacting the pedestrian 

mannequins at higher test speeds for S1 

and S4 than those specified in the 2019 

PAEB test procedure, and several 

vehicles repeatably achieved full crash 

avoidance at speeds up to 60 kph (37.3 

mph) or higher.222 These findings 

suggested that PAEB system 

performance at the time exceeded most 

of the testing requirements outlined in 

NHTSA’s 2019 PAEB test procedure. 

Specific to testing in dark lighting 

conditions, PAEB system performance 

generally degraded in dark conditions 

compared to daylight conditions, results 

which align well with IIHS’s system 

effectiveness study for 2017–2020 

model year vehicles. IIHS found that 

although PAEB systems were associated 

with a 32 percent reduction in 

pedestrian crashes occurring during 

daylight and a 33 percent reduction in 

pedestrian crashes for areas with 

artificial lighting during dawn, dusk, or 

at night, there was no evidence that 

PAEB systems were effective at 

nighttime without street lighting.223

With regard to overhead lighting, 

NHTSA’s data suggested that a vehicle’s 

PAEB system performs only slightly 

better with overhead lighting versus no 

overhead lighting. 

3. Model Year 2021 and 2022 Research 

Testing 

Subsequently, NHTSA conducted a 

series of PAEB research tests to further 

assess current fleet performance.224 This 

testing, which generally aligned well 

with NHTSA’s proposal for NCAP PAEB 

assessments, involved 12 model year 

2021 and 2022 light vehicles and 

included PAEB testing for the following 

PAEB test conditions: S1a, S1b, S1c, 

S1d, S1e, S4a, S4b, and S4c. Testing 

was conducted under both daylight and 

darkness lighting conditions. For 

darkness conditions, NHTSA evaluated 


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225For S4 scenarios, after 60 kph (37.3 mph), the 

next, and final, test speed was 65 kph (40.4 mph). 

226 Vehicle-to-pedestrian contact at the lowest test 

speed of 10 kph (6.2 mph) was noted but did not 

result in a cessation of testing at the next highest 

test speed. 

227https://www.regulations.gov/comment/ 

NHTSA-2021-0002-3613. See attachment 4. 

228Cicchino, J.B. (2022, February), Effects of 

automatic emergency braking systems on 

pedestrian crash risk, Insurance Institute for 

Highway Safety, https://www.iihs.org/api/ 

datastoredocument/bibliography/2243. 

229Safety Recommendation H–18–42. 

230Safety Recommendation H–18–43. 

the PAEB systems using lower beam 

headlamps, but for select conditions 

(S1b, S4a, and S4c), NHTSA also 

evaluated systems using upper beam 

headlamps. NHTSA utilized both adult 

and child articulated mannequins for 

this series. The goal of this research was 

to assess NHTSA’s PAEB proposals 

(outlined in subsequent sections) and to 

gain further knowledge regarding 

capabilities of the current vehicle fleet. 

See Table 18 below for nominal test 

parameters used in this series of 

research tests. 

TABLE 18—NOMINAL TEST PARAMETERS FOR MODEL YEAR 2021–2022 PAEB RESEARCH TESTING

Test 

condition Size 

Test speeds 

(kph (mph)) Movement 

classification Path origin Overlap (%) Obstruction Light condition 

SV Pedestrian 

S1a ........... Adult ................. 10, 20, 30, 40, 50, 60 (6.2, 12.4, 

18.6, 24.9, 31.1, 37.3).

5 (3.1) Walk ........... Right ........ 25 No .............. Daylight. 

Darkness—Lower Beam. 

S1b ........... Adult ................. 10, 20, 30, 40, 50, 60 (6.2, 12.4, 

18.6, 24.9, 31.1, 37.3).

5 (3.1) Walk ........... Right ........ 50 No .............. Daylight. 

Darkness—Lower Beam. 

Darkness—Upper Beam. 

S1c ........... Adult ................. 10, 20, 30, 40, 50, 60 (6.2, 12.4, 

18.6, 24.9, 31.1, 37.3).

5 (3.1) Walk ........... Right ........ 75 No ............... Daylight. 

Darkness—Lower Beam. 

S1d ........... Child ................. 10, 20, 30, 40, 50, 60 (6.2, 12.4, 

18.6, 24.9, 31.1, 37.3).

5 (3.1) Run ............. Right ........ 50 Yes ............. Daylight. 

Darkness—Lower Beam. 

S1e ........... Adult ................. 10, 20, 30, 40, 50, 60 (6.2, 12.4, 

18.6, 24.9, 31.1, 37.3).

8 (5.0) Run ............. Left ........... 50 No ............... Daylight. 

Darkness—Lower Beam. 

S4a ........... Adult (Facing 

Away).

10, 20, 30, 40, 50, 60 (6.2, 12.4, 

18.6, 24.9, 31.1, 37.3).

0 Stationary ... Right ........ 25 No ............... Daylight. 

Darkness—Lower Beam. 

Darkness—Upper Beam. 

S4b ........... Adult (Facing 

Toward).

10, 20, 30, 40, 50, 60 (6.2, 12.4, 

18.6, 24.9, 31.1, 37.3).

0 Stationary ... Right ........ 25 No .............. Daylight. 

Darkness—Lower Beam. 

S4c ........... Adult (Facing 

Away).

10, 20, 30, 40, 50, 60, 65 (6.2, 

12.4, 18.6, 24.9, 31.1, 37.3, 

40.4).

5 (3.1) Walk ........... Right ........ 25 No ............... Daylight. 

Darkness—Lower Beam. 

Darkness—Upper Beam. 

Like the Agency’s AEB 

characterization research, testing for 

each PAEB scenario advanced from the 

lowest SV speed to the highest, with one 

initial trial conducted per test speed. If 

the SV did not contact the pedestrian 

mannequin during the initial trial for a 

given speed, the SV speed was 

increased by 10 kph (6.2 mph) and the 

next trial was conducted. This iterative 

process continued until the maximum 

test speed was reached.225 However, if 

the SV contacted the pedestrian 

mannequin for the initial trial 

conducted for test speeds of 20 kph 

(12.4 mph) or greater, and the SV speed 

at the time of impact was at least 50 

percent less than the initial SV speed, 

the Agency performed up to four 

additional trials at the same SV 

speed.226 If the SV speed at the time of 

impact was 50 percent or greater than 

the initial SV speed, testing for that 

scenario ended. Relevant outcomes of 

this research are detailed throughout the 

applicable sections of this notice. 

Overall, vehicle performance in this test 

series was shown to have improved 

from the already relatively strong model 

year 2019–2020 research test series. 

D. Summary of Comments, Response to 

Comments, and Agency Decisions 

Pedestrian Automatic Emergency 

Braking Technology Inclusion in 

General 

Broadly, commenters were in favor of 

evaluating PAEB systems on new 

vehicle models. Many noted that 

pedestrian and cyclist fatalities are 

rising quickly relative to vehicle 

occupant fatalities. NSC presented data 

to show that in 2020, an estimated 6,721 

pedestrians were killed, a 33-year high. 

On a local level, several city 

governments, transportation 

departments, and advocacy groups 

submitted pedestrian crash data from 

their own cities to support inclusion of 

PAEB evaluations in NCAP (Portland, 

OR; Minneapolis, MN; Boston, MA; 

Philadelphia, PA; New York, NY; and 

Bike Anchorage, among others). Data 

supplied by Bosch showed that an 

estimated 21,300 crashes with injuries 

and/or fatalities could be eliminated 

each year assuming full fleet penetration 

of PAEB.227 Bosch also presented data 

from IIHS that showed the presence of 

a PAEB system results in a 25 to 27 

percent reduction in the risk of overall 

pedestrian crashes and a 29 to 30 

percent reduction in risk of injurious 

pedestrian crashes.228 Advocates stated 

that the research, analyses, and 

justification laid forth in the March 

2022 RFC notice were detailed and 

sound, and CR suggested that the 

Agency should take action as quickly as 

possible given the rapid rise in crashes 

involving VRUs. 

NSC also noted that VRU protection is 

one of the ‘‘largest gaps’’ in the current 

NCAP. In general, commenters strongly 

favored a paradigm shift in NHTSA’s 

vehicle ratings program. NCAP ratings 

currently address safety of the vehicle 

occupants only; however, many wished 

to see the safety information provided 

expand beyond the vehicle and extend 

to VRUs in the wider community. Some 

individuals indicated that they do not 

feel safe as a VRU. Commenters often 

stated that only vehicle purchasers (i.e., 

not VRUs) can choose vehicles that are 

designed to protect VRUs. Aptiv stated 

that vehicle-to-VRU scenarios should be 

treated with greater stringency than 

vehicle-to-vehicle scenarios because of 

the risk of severe injury and/or fatality 

to those outside of the vehicle. NTSB 

stated it has previously called on 

NHTSA to implement performance tests 

for evaluating PAEB systems 229 and to 

incorporate them into NCAP,230 noting 

that these actions might incentivize 

vehicle manufacturers to include and 

improve PAEB systems. 


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95986 Federal Register / Vol. 89, No. 232 / Tuesday, December 3, 2024 / Notices 

231As detailed in the March 2022 RFC notice, 

Volpe’s 2011–2015 FARS data set showed that 36 

percent of pedestrian fatalities occurred in the dark 

with no overhead lights. 

232National Center for Statistics and Analysis. 

(2023, June), Pedestrians. (Traffic Safety Facts, 2021 

Data. Report No. DOT HS 813 458), Washington, 

DC: National Highway Traffic Safety 

Administration. 

233Carpenter, M.G., Moury, M.T., Skvarce, J.R., 

Struck, M. Zwicky, T.D., & Kiger, S.M. (2014, June), 

Objective tests for forward looking pedestrian crash 

avoidance/mitigation systems: Final report (Report 

No. DOT HS 812 040), Washington, DC: National 

Highway Traffic Safety Administration. 

234 ISO/CD 19237:2017. 

235NHTSA–2021–0002–3847. 

Comments received in response to 

NHTSA’s proposal are summarized 

below, along with the corresponding 

Agency decision. 

1. Test Conditions for S1 and S4, 

Including False Positive Assessments 

S1f and S1g and Varying Lighting 

Conditions 

Because the Agency is committed to 

reducing test burden whenever 

appropriate, NHTSA proposed to 

include Scenarios S1a–e and S4a–c in 

its upcoming NCAP assessment but 

sought comments on the necessity of 

running each test condition to 

adequately address the safety problem. 

Further, NHTSA did not propose to 

include PAEB false positive test 

conditions (i.e., S1f and S1g) in NCAP 

in its March 2022 notice. However, it 

requested comment on whether the 

omission of these test conditions is 

acceptable. 

In addition to performing PAEB 

testing in daylight conditions, NHTSA’s 

proposal for PAEB in NCAP included 

executing scenarios S1a–e and S4a–c in 

dark lighting conditions to simulate 

nighttime pedestrian encounters. As 

detailed in the RFC notice and by many 

commenters, nighttime travel is risky for 

VRUs.231 In 2021, most pedestrian 

fatalities occurred in the dark (77 

percent).232 NHTSA sought comment on 

this approach. 

Summary of Comments 

Several commenters stated that the 

Agency should move forward with the 

proposed PAEB test conditions. 

Specifically, Uhnder, CAS, FCA, AAA, 

ASC, Intel, and one individual 

submitted comments in support of 

moving forward with test conditions 

S1a–e and S4a–c. CAS and the 

individual commenter noted that 

reducing test burden without empirical 

evidence supporting this decision will 

not adequately address the safety 

problem. AAA asserted that inclusion of 

the proposed test plan would 

‘‘characterize system response to 

variations of kinematic characteristics 

realistically encountered in the 

naturalistic environment.’’ To reduce 

test burden while maintaining realworld relevance and test stringency, 

Intel reasoned that, since these test 

conditions are all well-known to 

industry and have been defined in 

existing international regulations, 

NHTSA could require OEMs to selfreport predicted performance data and 

the Agency could ‘‘spot-check’’ results, 

reflecting Euro NCAP’s methodology. As 

an alternative approach to reduce 

burden, Toyota posed that NHTSA 

could determine a subgroup of certain 

scenarios (and/or test speeds) that will 

ensure adequate performance across a 

range of conditions/speeds and run this 

subgroup of tests rather than the full 

battery. Instead of reducing the test 

matrix at this time, Uhnder and ASC 

suggested NHTSA could re-evaluate the 

necessity for each test condition on a 

regular basis; at that time, tests could be 

reduced if there is no longer a need. 

Several other commenters provided 

general input on which test conditions 

should be selected for inclusion. 

Mercedes-Benz and Advocates noted 

that test conditions selected should 

reflect real-world conditions and needs, 

and those needs should be supported by 

statistically significant data. Advocates 

added that NHTSA should select test 

conditions which give the Agency 

confidence that the system will operate 

as intended by the manufacturer. 

Some commenters recommended 

specific reductions for the proposed test 

conditions. Pertinent comments are 

summarized below. 

S1 Test Conditions 

Many commenters requested the 

Agency reduce the test plan proposed 

for the S1 scenario. HATCI, Honda, 

Auto Innovators, MEMA, GM, and BMW 

supported removal of S1b, a test 

condition involving an adult-sized 

pedestrian mannequin entering the 

roadway from the nearside with 50 

percent overlap of the vehicle at point 

of contact. HATCI’s rationale for 

removal of S1b was that the 25 percent 

(S1a) and 75 percent (S1c) overlap 

conditions address the 50 percent 

condition adequately; therefore, the S1b 

test condition would be redundant. 

Bosch, Honda, MEMA, BMW, and Auto 

Innovators agreed with HATCI’s 

sentiments. GM supported this rationale 

for a pass/fail scoring system; however, 

the manufacturer recommended that the 

Agency adopt a wider range of test 

conditions if NCAP ratings would be 

assigned according to a points-based 

system. Some of the same commenters 

supporting a reduction in the test matrix 

for the S1 scenario (Honda, Auto 

Innovators, BMW) asserted that S1c 

should also be removed because they 

considered the S1a (25 percent overlap) 

condition to be the most stringent test 

case. TRC also stated that S1c was 

redundant and could be removed for 

similar reasons; the laboratory did not 

mention removal of S1b. Mercedes-Benz 

supported harmonization with 

international test protocols for the PAEB 

crossing conditions whenever possible. 

Similarly, Bosch recommended 

harmonization with Euro NCAP’s PAEB 

evaluation. 

S4 Test Conditions 

For the S4 scenarios, Mercedes-Benz, 

Auto Innovators, Subaru, and BMW 

recommended NHTSA remove both S4a 

and S4b from its test plan. S4a and S4b 

both involve the use of a stationary 

pedestrian mannequin situated on the 

nearside of the road at a 25 percent 

overlap facing away from (S4a) or 

towards (S4b) the SV. Mercedes-Benz 

was unsupportive of the use of 

stationary targets, citing data from three 

resources: a Volpe study, which did not 

identify any stationary scenarios; 233 an 

ISO standard, which does not prescribe 

the use of any stationary pedestrian tests 

due to low occurrence; 234 and a 

Mercedes-Benz study of German In 

Depth Accident Study (GIDAS) data, 

which revealed that only 4 percent of 

pedestrians struck were stationary.235

Subaru recommended that NHTSA 

focus on the S4c test condition, showing 

FARS data from 2016–2020 that 

indicated 61% of pedestrians struck 

alongside a roadway were walking in 

the direction of traffic. Auto Innovators, 

Honda, GM, and BMW reasoned that 

S4b is redundant with S4a since the 

only difference is the direction of the 

pedestrian, but Auto Innovators and 

BMW went on to state, similar to 

Subaru, that S4a and S4b may both be 

eliminated since S4c scenarios are more 

common in the real world. MEMA, 

Bosch, and Toyota were in favor of 

including either S4a or S4b, but not 

both, with Bosch encouraging the 

Agency to harmonize with the 

corresponding PAEB test procedures 

used by Euro NCAP. NACTO did not 

offer support for specific in-path 

condition, but the group noted that it is 

important for PAEB systems to detect 

stationary pedestrians. 

Removal of Select Test Conditions 

IIHS took a different approach in its 

comments, stating that its consumer 

information program includes scenarios 

S1a, S1d, and S4c. S1d is a test scenario 

in which a child-sized pedestrian 


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236https://www.regulations.gov/comment/ 

NHTSA-2021-0002-4068. ‘‘Of 186 systems on 

vehicles from 29 automakers that we examined in 

2021, 46% were superior, 34% were advanced, 5% 

were basic, 1% received no credit, and 13% were 

not available with pedestrian detection. Of those 

rated advanced or superior, 68% were standard 

equipment rather than optional features. Systems 

receiving a superior rating can avoid or 

substantially reduce the impact speed in almost all, 

if not all, three scenarios.’’ 

mannequin enters the roadway from the 

nearside behind parked vehicles with 50 

percent overlap of the vehicle. IIHS 

recommended that NHTSA focus on 

expediting rulemaking efforts for AEB/ 

PAEB, stating that model year 2021 

vehicles examined by the group 

performed exceedingly well.236 Should 

the Agency pursue PAEB rating in 

NCAP, the group suggested removal of 

the three tests that it currently conducts 

(S1a, S1d, and S4c) to reduce 

unnecessary test burden, indicating that 

any consumer confusion could be 

mitigated by explaining that the two 

programs are meant to be 

complementary. 

False Positive Test Conditions (S1f and 

S1g) 

Regarding false positive test 

conditions S1f and S1g, most 

commenters suggested that false 

positive tests should not be conducted 

in NCAP for PAEB. Bosch, Toyota, 

Honda, FCA, AAA, GM, Auto 

Innovators, BMW, and IIHS were not in 

favor of including S1f and S1g. Toyota 

submitted data to show that, due to 

tolerance overlap between the ‘‘off’’ and 

‘‘on’’ conditions, there is a risk of 

leaving PAEB off when it should remain 

on. Bosch, Auto Innovators, Honda, and 

BMW echoed this sentiment. For 

instance, Bosch noted the 

unpredictability of pedestrians and 

suggested that it is safer for a vehicle to 

stop if there is a chance that the 

pedestrian will enter the vehicle’s path. 

Bosch suggested that NHTSA should be 

cautious not to incorporate scenarios 

that may prompt a vehicle to continue 

driving when a pedestrian may continue 

into the vehicle’s path, as this may 

erode consumer confidence and trust in 

PAEB systems. Similarly, AAA stated 

that automakers should not be 

‘‘pressured to minimize false positives 

at the possible expense of reduced 

system efficacy.’’ Along these lines, FCA 

asserted that designing for S1f and S1g 

conditions may negatively affect tuning 

and calibration. IIHS and GM both 

noted that stakeholders could collect 

data on false activations by monitoring 

real-world field performance data. They 

claimed that this will be more useful 

since the test conditions outlined by the 

Agency will not address the full variety 

of situations in which false activations 

may occur in the field. They also noted 

that manufacturers have a vested 

interest in minimizing false positives to 

improve customer satisfaction. 

Conversely, a few commenters were 

in favor of adding false positive test 

conditions S1f and S1g to the battery of 

NCAP PAEB tests. TRC noted that 

vehicles still brake during these false 

positive tests, and thus reasoned that 

manufacturers may continue to increase 

system robustness if included in NCAP. 

Rivian stated that false positive 

conditions should be included since 

these situations occur in the field and 

braking unnecessarily and on short 

notice can contribute to the rear-end 

crash problem. CAS cited concern for 

various groups of VRUs, such as 

children, compromised adults, and 

animals, in its support for false positive 

testing. Like Bosch (above), CAS 

mentioned that these VRUs may first 

stop at the edge of the roadway but then 

continue crossing or reverse direction. 

Unlike Bosch, however, CAS suggested 

that the Agency should conduct false 

positive testing to ensure PAEB systems 

include additional safety margins and 

provide adequate protection. Adasky 

stated that false positive results serve as 

an indication of a lack of system 

robustness and are therefore important 

to include. Aptiv also noted that fused 

sensor technology should minimize 

false positive activation. Intel was not 

opposed to the inclusion of scenarios 

S1f and S1g, but it also suggested that 

test parameters and criteria should be 

reviewed carefully. In Intel’s opinion, 

warnings or short braking intervals may 

be acceptable to the driver since the 

miss distance for the false positive 

scenarios is relatively small. The group 

noted that this especially holds true for 

cases where the SV speed is high and 

the pedestrian is crossing the path, as 

the driver may not be sure that there is 

enough time for the pedestrian to cross 

safely. Intel stated it would like to see 

the miss distance reviewed and road 

markings considered. 

Overall Need for PAEB Testing in 

Darkness Lighting Conditions 

Respondents from a variety of 

backgrounds approved of NHTSA’s 

decision to conduct PAEB testing in 

dark lighting conditions. Many 

suggested that PAEB testing in dark 

lighting conditions was critical given 

the real-world safety problem. 

Generally, commenters were concerned 

about the current effectiveness of PAEB 

systems, citing studies that showed 

PAEB systems do not work as well in 

low light as they do in daylight. These 

groups and individuals reasoned that 

NHTSA must evaluate PAEB systems in 

dark conditions to encourage 

improvements in system performance. 

Auto Innovators and HATCI requested 

more information from NHTSA 

regarding PAEB test procedures in dark 

lighting conditions and real-world 

nighttime crash conditions. Auto 

Innovators asked that NHTSA more 

clearly define nighttime parameters in 

its test procedure so that test 

repeatability could be guaranteed. 

Should NHTSA decide not to harmonize 

with Euro NCAP nighttime test 

procedures, HATCI reasoned that 

NHTSA should study U.S. areas prone 

to nighttime crash events to determine 

precise lux levels and other 

environmental conditions which might 

be representative of these high-incident 

areas. These specifications should then 

be incorporated into NCAP’s test 

procedures, increasing test repeatability. 

The automaker provided pedestrianrelated crash data gathered from Ann 

Arbor, MI, including recorded lux 

measurements for areas with the highest 

pedestrian crash risk. Similarly, 

Advocates suggested that NHTSA 

evaluate real-world data to determine 

which kinds of crashes are occurring 

most frequently in low light and dark 

conditions. The group mentioned that 

this data could help inform testing 

practices and may also suggest that 

other technologies, including LDW/LKA 

and BSW/BSI, should be evaluated 

under nighttime conditions as well. 

Two commenters, Toyota and Auto 

Innovators, asserted there was not a 

need for the Agency to conduct 

condition S1d runs at night. Both 

groups referred to an accident analysis 

that showed the percentage of 

pedestrian impacts with vehicle 

obstacles present is low and therefore 

suggested that NHTSA eliminate the 

nighttime assessment of this scenario. 

Response to Comments and Agency 

Decisions 

The Agency plans to adopt specific 

test conditions from the S1 and S4 test 

scenarios included in its 2019 PAEB test 

procedure for NCAP’s PAEB 

assessments. In particular, the Agency is 

adopting S1a, S1b, S1d, and S1e for 

crossing path conditions and S4a and 

S4c for in-path conditions. NHTSA will 

perform assessments for each of these 

test conditions in both daylight and 

darkness. 

The Agency recognizes that this 

decision conflicts with IIHS’s request 

that NHTSA consider removal of select 

test conditions, notably S1a, S1d, and 

S4c, because they are performed by 

IIHS. While NHTSA suggests that 

consumers review all available, 


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95988 Federal Register / Vol. 89, No. 232 / Tuesday, December 3, 2024 / Notices 

237 Yanagisawa, M., Swanson, E., Azeredo, P., & 

Najm, W.G. (2017, April), Estimation of potential 

safety benefits for pedestrian crash avoidance/ 

mitigation systems (Report No. DOT HS 812 400), 

Washington, DC: National Highway Traffic Safety 

Administration. 

reputable safety information to make 

purchasing decisions, the Agency’s 

safety information program should be 

informative enough to stand alone. 

Since NHTSA cannot guarantee that any 

information currently available from 

other entities will remain available in 

the same capacity indefinitely, the 

Agency should not omit certain test 

conditions simply because comparable 

ratings information is currently 

provided by another consumer program. 

However, NHTSA has decided to omit 

a few of the test conditions it proposed 

in its RFC from NCAP’s final PAEB test 

matrix based on comments received and 

recent Agency research. 

S1 Test Conditions 

As noted earlier, in 12 percent of 

pedestrian crashes involving injuries 

and 42 percent of crashes involving 

pedestrian fatalities, a light vehicle is 

traveling straight while a pedestrian 

enters the vehicle’s path from either the 

left or right side.237 These real-world 

crashes can be represented by the S1 

crossing path scenario. More 

specifically, the S1a–c test conditions 

involve an adult pedestrian walking into 

the roadway and into the SV’s path from 

the right side. For each of these three S1 

test conditions, S1a, S1b, and S1c, the 

pedestrian mannequin begins its 

crossing maneuver at different times 

prior to collision, thus resulting in 25, 

50, and 75 percent overlap, respectively, 

with the vehicle’s front end. 

Several commenters suggested that 

NHTSA include the 25 and 75 percent 

overlap assessments only (i.e., S1a and 

c, respectively). Euro NCAP assesses 

vehicles in these two test conditions, 

represented by their Car-to-Pedestrian 

Nearside Adult 25 percent (CPNA–25) 

and Car-to-Pedestrian Nearside Adult 75 

percent (CPNA–75) conditions, and 

does not perform a CPNA test at 50 

percent overlap. Commenters stated that 

the 25 and 75 percent overlap 

conditions sufficiently cover the 50 

percent overlap condition, making the 

S1b assessment superfluous. However, 

this assertion was not found to be 

accurate in the Agency’s model year 

2021–2022 research testing. One vehicle 

contacted the pedestrian mannequin in 

the S1b test at 60 kph (37.3 mph) but 

did not contact the mannequin for any 

of the other test speeds included for 

either the S1a or S1c conditions during 

daylight testing. Thus, if the Agency had 

not conducted S1b for this vehicle, the 

failure would not have been captured. 

Additionally, for a second vehicle, 

contact was observed at 50 kph (31.1 

mph) in the S1b test conducted during 

daylight but was not observed until 60 

kph (37.3 mph) in the S1a test. 

Similarly, during darkness testing with 

lower beam headlamps, three vehicles 

subjected to the S1b test condition 

contacted the pedestrian mannequin at 

50 kph (31.1 mph), whereas contact was 

not observed for the S1a test condition 

until 60 kph (37.3 mph). Given these 

findings, it is beneficial to adopt the S1b 

test condition. 

The Agency is also retaining the S1a 

condition from its proposal because 

doing so should ensure the system has 

an adequate operational field of view 

and is able to identify pedestrians that 

are not at the center of the travel path. 

In addition, this test condition was 

generally found to be more stringent, as 

several commenters suggested, with the 

only exceptions observed being the two 

vehicles previously mentioned for the 

S1b test. Although IIHS also performs 

tests that correspond to NHTSA’s S1a 

test, adopting this test condition for 

NCAP would be advantageous at this 

time given the results observed during 

the Agency’s model year 2021–2022 

research testing. Specifically, only four 

of the twelve vehicles tested were able 

to avoid contacting the pedestrian 

mannequin for every test speed assessed 

for the S1a test condition in daylight. 

This number was reduced to two during 

darkness testing with lower beam 

headlamps, with performance 

degradation generally beginning around 

40 kph (24.9 mph). While these results 

show this condition may be challenging 

for current PAEB systems, they also 

show that passing performance is 

practicable for all adopted test speeds. 

Although NHTSA has decided to 

retain the S1a and S1b test conditions 

for NCAP PAEB testing, it does not plan 

to adopt the S1c test condition (i.e., 

Euro NCAP’s CPNA–75 test). Because of 

the larger amount of overlap at the point 

of impact (75 percent) for the S1c 

condition, the vehicle is afforded an 

increased amount of time for the PAEB 

system to sense and react to the crossing 

pedestrian. NHTSA’s model year 2021– 

2022 research testing showed that 

vehicles which contacted the pedestrian 

mannequin in the S1c test condition 

also contacted the mannequin in either 

S1a or S1b at the same speed or at a 

lower speed for both daylight and 

darkness testing. Therefore, the Agency 

agrees with those commenters that 

stated that S1c is the least stringent of 

the S1a–c crossing path test conditions. 

The Agency also acknowledges Toyota’s 

recommendation that it should seek to 

reduce test burden in situations where 

it can remove a test condition and still 

ensure adequate performance across a 

range of conditions. Since system 

performance observed for the 75 percent 

overlap condition appears to be 

sufficiently addressed by the 25 percent 

and 50 percent overlap conditions, 

NCAP sees no need to also adopt the 

S1c test condition. 

The Agency has also decided to adopt 

the S1d test condition, which was 

particularly challenging for vehicles in 

the Agency’s recent testing series. 

Because the child mannequin emerges 

from behind an obstruction (parked 

vehicle along the SV’s path), the SV’s 

PAEB system has less time to detect and 

react to the pedestrian. No vehicle out 

of the 12 tested in the model year 2021– 

2022 test series achieved full avoidance 

for every test speed assessed for this test 

condition in either daylight or dark 

lighting condition. For daylight testing, 

four vehicles contacted the pedestrian 

mannequin in the first trial for the 60 

kph (37.3 mph) test at a speed less than 

50 percent of the initial speed (less than 

30 kph, or 18.7 mph), but none 

demonstrated full avoidance in at least 

three of the four retrials. However, three 

vehicles were able to repeatedly avoid 

contact up to and including 50 kph 

(31.1 mph). An additional vehicle 

contacted the pedestrian mannequin at 

10 kph (6.1 mph) in daylight but 

avoided contacting again until the 60 

kph (37.3 mph) test was conducted. 

Most often, for the other vehicles in the 

test series, performance degradation at 

higher speeds began occurring around 

40 kph (24.9 mph) during the daylight 

runs. During darkness testing, no 

vehicle was able to achieve full 

avoidance for three or more trials at test 

speeds of 40 kph (24.9 mph) or greater. 

Five vehicles exhibited contact with the 

pedestrian mannequin at the lowest test 

speed of 10 kph (6.1 mph). For the 

remaining seven vehicles, four 

contacted the mannequin with speed 

reductions of less than 50 percent at an 

SV initial speed of 40 kph (24.9 mph), 

two models contacted at 30 kph (18.6 

mph), and one model contacted at 20 

kph (12.4 mph). 

While subpar performance was 

observed for the S1d test condition, 

there is merit in including it in NCAP’s 

final PAEB test matrix for both daylight 

and dark lighting conditions. Several 

commenters mentioned that the realworld occurrence rate of this condition 

is relatively low in comparison to some 

of the other adopted test conditions, 

particularly with respect to the darkness 

variant. However, NHTSA notes that 

because of the shorter daylight time in 

fall and winter, it is possible for 


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238 Yanagisawa, M., Swanson, E., Azeredo, P., & 

Najm, W. G. (2017, April), Estimation of potential 

safety benefits for pedestrian crash avoidance/ 

mitigation systems (Report No. DOT HS 812 400), 

Washington, DC: National Highway Traffic Safety 

Administration. 

children to be walking after events, such 

as an evening soccer practice, in 

relatively dark lighting conditions. It is 

important to adopt the S1d condition for 

NCAP testing since it involves a child 

pedestrian and is one with which 

current vehicles especially struggle. 

NHTSA received a substantial number 

of comments in response to the RFC 

regarding child safety. 

Finally, NHTSA will adopt the test 

scenario S1e, which represents an adult 

pedestrian running into the vehicle’s 

path from the far, or left-hand, side. 

NHTSA received few comments 

regarding the applicability of this test 

condition. During the Agency’s model 

year 2021–2022 daylight testing series, 

two vehicles achieved full crash 

avoidance at all test speeds in the S1e 

condition, and an additional two only 

contacted the pedestrian mannequin 

during the 60 kph (37.3 mph) test speed. 

Nearly the same observations were 

made for the Agency’s lower beam 

headlamp darkness testing; two vehicle 

models avoided contact with the 

pedestrian mannequin at all assessed 

test speeds, and one additional model 

only contacted the mannequin at the 60 

kph (37.3 mph) test speed. Several 

vehicles that only experienced contact 

at higher test speeds during the S1b 

condition (where the pedestrian 

mannequin approaches the test vehicle 

from the right side at 50 percent 

overlap) did not perform as well for S1e, 

when the pedestrian entered at a faster 

speed from the left-hand side with the 

same overlap at the point of impact (50 

percent). This was true for both daylight 

and darkness testing with lower beams. 

It is critical to assess PAEB 

performance when the pedestrian is 

crossing from the left side as well as 

from the right, and while both walking 

and jogging. As several vehicles were 

able to perform well when subjected to 

the S1e condition in daylight, and two 

vehicles were able to provide complete 

avoidance for all test speeds in darkness 

with lower beams, NHTSA will include 

the S1e condition in NCAP at this time. 

S4 Test Conditions 

NHTSA has decided to include 

scenarios S4a and S4c in NCAP’s 

updated test matrix for both lighting 

variants. The in-path scenario, S4, 

which includes test conditions S4a, S4b, 

and S4c, represents a pedestrian 

standing alongside the roadway facing 

away from the vehicle (S4a) or towards 

the vehicle (S4b), or walking along with 

traffic away from the vehicle on the side 

of the roadway with a 25 percent 

overlap (S4c). Overall, the S4 scenario 

comprises 5 percent of pedestrian 

crashes involving injuries and 19 

percent of pedestrian fatalities.238

Regarding commenters’ concerns 

surrounding redundancy between the 

proposed stationary mannequin 

conditions (i.e., S4a and S4b), in its 

model year 2021–2022 research tests, 

NHTSA found that, when comparing 

daylight results for each vehicle, the S4a 

test condition, where the stationary 

mannequin was facing away from the 

SV, resulted in more frequent vehicleto-pedestrian contact across the 

incremented test trials compared to the 

S4b test condition, where the stationary 

mannequin was facing toward the SV. 

This same trend was observed for the 

Agency’s darkness testing. Given these 

findings, NHTSA agrees with 

commenters that adding both S4a and 

S4b test conditions is not necessary to 

achieve improved PAEB performance. 

Thus, the Agency has chosen not to 

adopt the seemingly less stringent test 

condition for the stationary mannequin, 

S4b, for NCAP to reduce testing burden. 

While the Agency is removing one of 

the in-path stationary mannequin tests 

from NCAP’s PAEB test matrix (i.e., 

S4b), it will not remove both stationary 

mannequin conditions, as some 

commenters requested. The Agency 

agrees with NACTO that stationary 

pedestrians should be accounted for 

when conducting PAEB testing; 

consumers expect PAEB systems to 

operate regardless of the pedestrian’s 

movement, or lack thereof. Testing 

using a stationary pedestrian may also 

help to mitigate crashes in which a law 

enforcement officer or other first 

responder is standing in the roadway. 

Based on the results of the Agency’s 

model year 2021–2022 research testing, 

in-path assessments for both stationary 

and moving pedestrian mannequins are 

necessary to ensure robust PAEB system 

performance. When comparing daylight 

results from the S4a tests to those for 

S4c, five vehicles contacted the 

mannequin at the uppermost test speed 

(60 kph (37.3 mph)) when the 

pedestrian was stationary (S4a), but not 

when it was moving (S4c). Furthermore, 

four vehicle models contacted the 

mannequin at the lowest test speed (10 

kph (6.2 mph)) for the moving 

mannequin test (S4c) but not for either 

stationary test (S4a or S4b). Similar 

findings were observed during the 

Agency’s darkness testing. Results for 

the S4a stationary mannequin condition 

with lower beam headlamps showed 

contact at 60 kph (37.3 mph) for three 

vehicles which was not similarly 

observed for the moving pedestrian 

condition. Furthermore, at 10 kph (6.2 

mph), seven vehicles contacted the 

moving mannequin target during the 

S4c darkness tests but did not contact 

the stationary mannequin target at this 

same test speed in the S4a tests. In 

addition, five of these seven vehicles 

exhibited no reduction in speed. This is 

concerning because, as the Agency has 

mentioned previously, even low-speed 

pedestrian crashes can be fatal. Further, 

as Subaru and others suggested, recent 

FARS data shows that the S4c test 

condition is representative of a 

common, fatal real-world crash. This is 

unsurprising since the pedestrian is 

facing away from the vehicle in these 

crashes and therefore may be unaware 

that a vehicle is approaching; if the 

driver of the vehicle is inattentive, it is 

even more likely that the vehicle may 

collide with the pedestrian. These 

results show that at very low and high 

speeds, PAEB systems may have trouble 

properly classifying moving and 

stationary pedestrians, respectively. 

Therefore, both stationary and moving 

targets should be assessed in NCAP’s 

PAEB tests in daylight and dark lighting 

conditions and will proceed with 

adopting the S4a and S4c test scenarios 

accordingly. 

Although many vehicles exhibited 

contact at higher and/or lower speeds 

for the S4a and S4c test conditions, 

three vehicles offered complete crash 

avoidance for all test speeds, up to and 

including 60 kph (37.3 mph) for both 

conditions during the Agency’s daylight 

assessments, thus showing that robust 

performance is practicable. Further, 

although no vehicles were able to 

completely avoid contact with the 

pedestrian mannequin for all test speeds 

during darkness testing for the NCAPadopted S4a and S4c scenarios, one 

vehicle only contacted the pedestrian 

mannequin at 10 kph (6.2 mph) for both 

conditions (i.e., S4a and S4c). In fact, of 

the 10 vehicles exhibiting contact at 10 

kph (6.2 mph) in at least one of the two 

S4 test conditions in dark lighting being 

adopted, four avoided contacting the 

mannequin again completely during 

higher-speed tests in the scenario and 

three avoided contact until 60 kph (37.3 

mph). These results demonstrate the 

achievability of future iterations of 

PAEB systems to fully avoid pedestrians 

for in-path stationary and moving 

pedestrian test conditions during 

assessments in both daylight and dark 

lighting conditions, making adoption of 

scenarios S4a and S4c in NCAP’s 


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95990 Federal Register / Vol. 89, No. 232 / Tuesday, December 3, 2024 / Notices 

updated test matrix reasonable for both 

lighting variants. 

False Positive Test Conditions (S1f and 

S1g) 

Regarding the false positive test 

conditions S1f and S1g, the Agency will 

not adopt these test conditions for 

NCAP’s PAEB testing at this time. 

Despite the risk of drivers disabling 

PAEB if too many unnecessary 

activations occur, comments received 

regarding NCAP’s inclusion of false 

positive testing negatively affecting 

system efficacy is also of concern, 

especially given the inherently 

vulnerable nature of those outside the 

vehicle. Data submitted by Toyota 

demonstrated that there is a potential 

overlap in the S1b and S1f cases up to 

0.8 seconds TTC. As a result, systems 

may either falsely activate when it is not 

appropriate, or they may not activate 

when it is necessary to do so. Fewer 

false positive activations should not 

come at the expense of increased false 

negatives. Further, pedestrian behavior 

can be unpredictable, as Bosch noted. If 

there is a reasonable chance that the 

pedestrian will enter the vehicle’s path, 

the vehicle’s PAEB system should be 

prepared to react accordingly. The 

Agency reasons, as Intel suggested, that 

drivers will accept false activations in 

cases where the miss distance is small, 

especially at higher vehicle speeds, 

since the driver may not be certain that 

the individual will indeed avoid the 

vehicle’s path. Additionally, NHTSA 

agrees that manufacturers have an 

interest in maintaining customer 

satisfaction. The lack of false positive 

testing does not prevent a manufacturer 

from optimizing its designs and 

improving sensor technology and 

system robustness. Nevertheless, the 

Agency plans to monitor real-world 

performance data to ensure that 

nuisance activations do not become 

problematic, especially given the 

numerous situations that may occur in 

the field. As mentioned for AEB, 

vehicles that have excessive false 

positive activations may pose an 

unreasonable risk to safety and, as such, 

may be considered to have a safetyrelated defect. 

The Agency acknowledges that its 

decision not to add false positive tests 

for PAEB is a departure from its 

treatment of false positive testing for 

AEB. NHTSA expects that a vehicle 

should encounter near-miss pedestrians 

relatively less frequently than it 

encounters near-miss situations with 

other vehicles. Therefore, a deficient 

PAEB system design should produce 

fewer unnecessary activations than a 

deficient AEB system. However, it is the 

Agency’s intent to periodically revisit 

its review of the crash problem and 

adjust scenarios and test conditions 

accordingly, not only for false positive 

testing and PAEB assessments but for all 

ADAS testing. 

Need for PAEB Assessments in Daylight 

and Dark Lighting Conditions 

Given the significant safety need 

described earlier in this notice, the 

proven feasibility of conducting PAEB 

testing in dark lighting conditions, and 

the ability for current systems to meet 

requirements, assessments in both 

daylight and dark lighting conditions 

are suitable for the adopted NCAP PAEB 

test conditions. 

For the adopted S1 crossing path test 

conditions (i.e., S1a, S1b, S1d, and S1e), 

one vehicle in the Agency’s model year 

2021–2022 research testing was able to 

achieve full crash avoidance from 10 

kph to 60 kph (6.2 mph to 37.3 mph) in 

all but one test condition, S1d, during 

testing in both daylight and dark 

lighting conditions using the vehicle’s 

lower beam headlamps. For the S1d 

dark lighting test condition, the vehicle 

afforded full crash avoidance up to and 

including 30 kph (18.6 mph). 

Additionally, although eight of the 12 

vehicles contacted the pedestrian 

mannequin in each of the four crossing 

path conditions being adopted for 

NCAP’s assessments in dark lighting 

conditions, three of these eight were 

able to achieve full avoidance in at least 

one crossing path test condition during 

daylight testing. These results show that 

excellent PAEB response in S1 dark 

lighting test conditions can be achieved, 

like those observed for testing in 

daylight, but for many vehicle models, 

there are further gains to be made 

specifically for PAEB performance 

under dark lighting conditions. 

For the adopted S4 in-path conditions 

and test speeds (i.e., S4a and S4c), five 

of the 12 models were able to fully 

avoid the mannequin target during 

daylight testing for at least one in-path 

condition; three of these five afforded 

full crash avoidance for both S4a and 

S4c test conditions. While none of the 

vehicles achieved full crash avoidance 

in either of the two adopted in-path test 

conditions during testing in the dark 

lighting condition using the vehicle’s 

lower beam headlamps, many 

performed well between 20 kph and 50 

kph (12.4 mph and 31.1 mph) for both 

S4 test conditions. Furthermore, 

although eight out of 12 vehicle models 

failed to avoid the pedestrian 

mannequin in the S4c test condition at 

10 kph (6.2 mph) in the dark lighting 

condition (with lower beam headlamps), 

only five of these same models failed 

this test condition variant during the 

corresponding tests in daylight. These 

results suggest that robust performance 

is achievable in both daylight and 

darkness assessments for the selected 

in-path test conditions; however, 

performance in one lighting condition 

does not necessarily translate to the 

other lighting condition. 

While the Agency acknowledges that 

its model year 2021–2022 PAEB testing 

demonstrated that current systems 

provided wide-ranging system 

capabilities during darkness testing for 

the adopted test conditions, it sees no 

reason to reduce the test matrix for 

testing in dark lighting condition, other 

than for the speed maximum speed to be 

assessed for the S1d condition, as will 

be discussed in the next section. 

NHTSA’s research test results suggest 

that installation of improved sensing 

capabilities should allow for improved 

nighttime PAEB performance that more 

closely mirrors the performance 

observed during daylight. Further, the 

Agency reasons there is no reason to 

conduct only testing in darkness and 

forgo testing in daylight. As mentioned 

earlier, a significant number of 

pedestrian crashes occur in both 

lighting conditions. As such, the Agency 

must ensure system changes made to 

improve performance in darkness do not 

affect performance in daylight, and vice 

versa. In addition, because of the vast 

differences in current PAEB system 

capabilities, it is most reasonable to 

offer PAEB credit for performance in 

daylight separate from that of 

performance in darkness. By proceeding 

in this manner, the Agency expects it 

can more quickly award partial PAEB 

credit to current systems that may 

require relatively minor changes (i.e., to 

software) to perform successfully for all 

test variants in daylight. 

2. Test Speeds 

Like its plan for AEB, NHTSA 

proposed to assess PAEB system 

performance over a range of test speeds 

for each of the test scenarios considered 

for inclusion. Specifically, NHTSA 

proposed to increase the SV test speed 

in 10 kph (6.2 mph) increments from a 

minimum test speed of 10 kph (6.2 

mph) to a maximum test speed of 60 

kph (37.3 mph) for each test condition, 

performing one trial per speed. To 

achieve a passing result for each speed, 

the Agency stipulated that the test trial 

must be valid (all test specifications and 

tolerances satisfied), and the SV must 

not contact the pedestrian mannequin. 

As will be discussed later, similar to its 

research testing of model year 2021 and 

2022 vehicles, the Agency further 

suggested that it would conduct up to 


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Federal Register / Vol. 89, No. 232 / Tuesday, December 3, 2024 / Notices 95991 

239The Agency hesitated to draw conclusions 

based solely on the travel speed data due to its 

significant limitations. The travel speed was either 

not reported or was unknown in 59 percent of fatal 

pedestrian crashes and 72 percent of pedestrian 

crashes that resulted in injuries. That being said, 

this data did show similar trends to that observed 

for posted speeds. For crashes that occurred on 

roadways where the travel speed was known, 14 

percent of pedestrian fatalities and 70 percent of 

pedestrian injuries were reported for travel speeds 

of 40.2 kph (25 mph) and less, whereas 36 percent 

of fatalities and 85 percent of injuries occurred for 

travel speeds of 60 kph (37.3 mph) and less. Like 

the posted speed data, the known travel speed data, 

although limited, also showed that adopting the 

higher maximum test speed of 60 kph (37.3 mph) 

would allow the Agency to capture additional 

fatalities and injuries, 21 percent and 15 percent, 

respectively. 

240Carpenter, M.G., Moury, M.T., Skvarce, J.R., 

Struck, M. Zwicky, T.D., & Kiger, S.M. (2014, June), 

Objective tests for forward looking pedestrian crash 

avoidance/mitigation systems: Final report (Report 

No. DOT HS 812 040), Washington, DC: National 

Highway Traffic Safety Administration. 

four additional trials for any specific 

test speed that resulted in a test failure 

(i.e., contact) as long as the SV had a 

relative velocity at impact equal to or 

less than 50 percent of the initial SV test 

speed. In such instances, NHTSA 

proposed that the SV must not contact 

the pedestrian mannequin for at least 

three out of the five total trials 

conducted to pass the test condition 

(i.e., combination of test scenario and 

test speed). 

The Agency believed it was 

appropriate to increase the maximum 

SV test speed from the 40 kph (24.9 

mph) specified in its 2019 PAEB test 

procedure to 60 kph (37.3 mph) for all 

PAEB test conditions proposed for 

inclusion in NCAP for several reasons. 

First, as detailed in the real-world data 

section earlier, NHTSA reasoned that 

adopting a higher maximum PAEB test 

speed was necessary to drive improved 

PAEB system performance and address 

a larger portion of real world injuries 

and fatalities.239 Second, the Agency 

found that performing PAEB testing at 

60 kph (37.3 mph) was reasonable, as 

NHTSA’s model year 2019–2020 (and 

subsequent model year 2021–2022) 

research testing showed that robust 

PAEB system performance across 

various test conditions was achievable 

at this higher test speed. Further, Euro 

NCAP prescribes a maximum vehicle 

speed of 60 kph (37.3 mph) in its PAEB 

testing for test conditions similar or 

identical to those proposed; in 

particular, S1a, S1c, S1d, S1e and S4c. 

Harmonizing test speeds with Euro 

NCAP should reduce manufacturer 

burden while also fulfilling mandates 

stipulated in the Bipartisan 

Infrastructure Law, which requires that 

the Agency take steps to harmonize with 

existing consumer information rating 

programs where possible and when 

appropriate. 

The Agency’s reasons for proposing 

the minimum test speed of 10 kph (6.2 

mph) for the planned PAEB test 

conditions were similar to those used to 

justify the proposed maximum test 

speed: harmonization and real-world 

relevance. Although the minimum test 

speed proposed is lower than the 

minimum speed prescribed in NHTSA’s 

2019 PAEB test procedure and in its 

characterization testing (i.e., 16 kph (9.9 

mph)), the Agency noted that it aligns 

with the minimum test speed specified 

in Euro NCAP’s pedestrian tests, except 

for Euro NCAP’s Car-to-Pedestrian 

Longitudinal Adult (CPLA) scenario. 

The minimum vehicle test speed for the 

CPLA scenario, which is similar to the 

Agency’s PAEB S4c test condition, is 20 

kph (12.4 mph). NHTSA also believed 

that reducing the minimum test speed to 

10 kph (6.2 mph) would ensure PAEB 

system functionality for very low speed 

crashes that may still cause injuries. 

Such injuries incurred from low-speed 

pedestrian collisions often result from 

secondary impacts with the ground. 

NHTSA also proposed to adopt Euro 

NCAP’s approach to assessing vehicles’ 

PAEB system performance by 

incrementally increasing the SV speed 

from the minimum test speed for a given 

scenario to the maximum. The Agency 

reasoned that such an approach would 

(1) harmonize with other consumer 

information programs on vehicle safety, 

(2) address comments received in 

response to NHTSA’s December 2015 

notice to expand the applicability of 

PAEB tests to include a broader range of 

test speeds, thus addressing a broader 

range of crash speeds driving pedestrian 

injuries and fatalities, and (3) ensure 

future PAEB systems effectively manage 

the inherent trade-off between a wider 

field-of-view needed for lower speed 

impacts and a narrower field-of-view 

necessary for distance detection in 

higher speed crashes. The Agency 

proposed 10 kph (6.2 mph) increments 

for the test speed progression. 

The Agency sought comment on 

whether the proposed speeds and 

overall assessment approach were 

appropriate or whether alternatives 

should be considered. 

Summary of Comments 

Many commenters agreed with the 

Agency’s plan to set lower and upper 

bounds for SV test speed in PAEB 

testing to 10 kph (6.2 mph) and 60 kph 

(37.3 mph), respectively. Toyota, 

Advocates, MEMA, NYC DOT/NYC 

DCAS Vision Zero Task Force, IDIADA, 

AAA, ASC, FCA, Rivian, Uhnder, BMW, 

Intel, HATCI, and ZF Group stated that 

this range of speed was appropriate. 

Some of those in favor mentioned that 

this speed range is representative of 

urban driving conditions to which 

pedestrians are typically exposed (roads 

with speed limits of 35 mph or less) 

(NYC DOT/NYC DCAS Vision Zero Task 

Force, IDIADA, ASC, Uhnder, and 

Intel). Others (FCA and Rivian) noted 

that this speed range would lessen the 

testing burden for manufacturers 

because it aligns with Euro NCAP’s 

PAEB speed range. Advocates, AAA, 

and Rivian cited the need to ensure that 

the technology works across a spectrum 

of vehicle speeds to address both lowerand higher-speed pre-impact scenarios, 

but Advocates added that NHTSA 

should continue to evaluate whether the 

proposed speed ranges will be adequate 

to protect all VRUs. 

Although Toyota agreed with the test 

speed range proposed by the Agency, it 

noted that physical intervention at 

higher speeds may interfere with a 

driver’s ability to intentionally 

maneuver to avoid the collision since 

the vehicle must begin braking earlier. 

In addition, Toyota suggested that if 

there is a test speed (or subgroup of 

speeds) at which system performance is 

most representative of the entire speed 

spectrum, testing at that speed would be 

the most preferable solution as it would 

be the most efficient method to 

disseminate information to the public. 

Auto Innovators and GM also remarked 

that tests with SV speeds higher than 60 

kph (37.3 mph) are more likely to 

damage test equipment. State Farm was 

generally supportive of higher vehicle 

speeds and conditions representative of 

real-world cases. 

Minimum Test Speed Changes 

A few commenters disagreed with the 

lower boundary of NHTSA’s proposed 

speed range. GM requested that the 

Agency begin testing PAEB S1 and S4 

scenarios at 20 kph (12.4 mph). The 

automaker noted that the speed range of 

20 kph (12.4 mph) to 60 kph (37.3 mph) 

is supported by other global consumer 

metrics and is referenced in a NHTSAsupported project.240 Auto Innovators 

and Honda requested that NHTSA allow 

vehicle manufacturers to select the 

minimum speed for PAEB testing, 

reasoning that modern AEB sensors are 

designed to prioritize functionality at 

higher, more injurious speeds. Since the 

speed differential between the SV and 

the pedestrian is lower at lower speeds, 

the pedestrian enters the AEB sensor 

field-of-view at a wider angle than at 

higher speeds. IDIADA also echoed this 

sentiment. Both groups noted that Euro 

NCAP and Japan New Car Assessment 


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241Euro NCAP prescribes a 20 kph (12.4 mph) 

lower speed threshold for its CPLA scenario, which 

is comparable to NHTSA’s S4c test. 

242European New Car Assessment Programme 

(Euro NCAP) (December 2023), Test Protocol—AEB/ 

LSS VRU systems, Version 4.5. 

243See ‘‘Linking Proposed PAEB Test Scenarios 

with Real-World Crashes’’ section of this notice. 

Program (JNCAP) allows manufacturers 

to select the minimum speed. 

Maximum Test Speed Changes 

The upper speed range was also 

questioned by several commenters. 

Vision Zero Network, NTSB, CAS, 

League of American Bicyclists, and a 

number of individuals commented that 

they would like the Agency to run PAEB 

testing at speeds higher than 60 kph 

(37.3 mph). NTSB disagreed with 

NHTSA regarding its logic for selecting 

the upper test speed, stating that test 

specifications should not be based on 

current system capabilities but instead 

should drive systems toward ideal 

performance. CAS suggested that 

NHTSA determine the upper limits for 

each model’s PAEB system to 

discourage designing to the test and to 

allow consumers to identify vehicles 

with superior performance. Vision Zero 

Network cited an IIHS study which 

found that PAEB is not efficient in areas 

with speed limits of 80.5 kph (50 mph) 

or greater. The League of American 

Bicyclists did not provide a preferred 

upper speed limit; however, the 

advocacy group did provide pedestrian 

fatality data to support upper speeds 

anywhere from 56.3 kph (35 mph) to 

88.5 kph (55 mph). Advocates, while 

supporting the speed range overall, also 

suggested that NHTSA evaluate whether 

the upper test speed limit is sufficient 

to capture the full range of real-world 

incidents. ZF Group supported 

increasing the test speed for test 

scenario S4c up to 80 kph (49.7 mph), 

as it could evaluate system capability in 

a pre-crash scenario involving a 

pedestrian walking along a rural road or 

highway with a higher speed limit. 

Comments from individuals were 

mostly in favor of increasing the speed 

range to anywhere from 64.3 kph (40 

mph) to 120.7 kph (75 mph). 

Incremental Speed Changes 

Regarding speed intervals between the 

minimum and the maximum, some 

(HATCI, ZF Group, and one individual) 

specifically offered support for 10 kph 

(6.2 mph) speed intervals. ASC 

recommended that NHTSA use three 

test speeds to evaluate the range of 

performance more efficiently: 10 kph 

(6.2 mph), 35 kph (21.7 mph), and 60 

kph (37.3 mph). Adasky suggested that 

NHTSA drop to three test speed 

increments instead of six to allow 

resources to test a wider range of 

scenarios. 

Response to Comments and Agency 

Decisions 

NHTSA will begin testing for each of 

the adopted PAEB test conditions at a 

minimum SV speed threshold of 10 kph 

(6.2 mph) and will increase the SV 

speed in 10 kph (6.2 mph) increments 

until a maximum speed threshold is 

reached, as long as the test vehicle does 

not make contact with the pedestrian 

mannequin during each progressive 

speed tested. For test conditions S1a, 

S1b, S1e, S4a, and S4c, the Agency is 

adopting a maximum SV speed 

threshold of 60 kph (37.3 mph) for both 

daylight and dark testing. For test 

condition S1d, the Agency is adopting 

a maximum SV speed threshold of 60 

kph (37.3 mph) for daylight testing and 

40 kph (24.9 mph) for dark testing. 

Travel speeds adopted for the 

pedestrian mannequins align with those 

proposed—5 kph (3.1 mph) for the 

walking adult test conditions (S1a, S1b, 

and S4c) and the running child test 

condition (S1d), 8 kph (4.9 mph) for the 

running adult test condition (S1e), and 

0 kph (0 mph) for the standing adult test 

condition (S4a). Should vehicle-tomannequin contact occur at any speed, 

the test laboratory will discontinue the 

PAEB test series for the relevant lighting 

condition. 

Citing real-world relevance, testing 

feasibility, and reduced test burden due 

to harmonization, commenters generally 

favored the lower speed threshold (i.e., 

10 kph (6.2 mph)) proposed by NHTSA. 

A few commenters, however, requested 

that NHTSA adopt an alternative 

minimum speed threshold, either one 

dictated by vehicle manufacturers’ 

preference or 20 kph (12.4 mph) to align 

with other consumer testing programs. 

NHTSA reasons it is inappropriate to 

allow vehicle manufacturers to select 

the minimum speed for testing simply 

because some vehicles may currently 

prioritize functionality at higher, more 

injurious speeds, as Honda and Auto 

Innovators asserted. A vehicle striking a 

pedestrian at low speeds, such as 10 

kph (6.2 mph), can still result in serious 

injuries or a fatality. Also, the minimum 

PAEB test speed of 10 kph (6.2 mph) is 

acceptable for NCAP’s test matrix 

because it aligns with the lower-most 

test speed utilized by Euro NCAP for its 

CPNA, CPNCO, and CPFA tests, which 

are comparable to the Agency’s S1a and 

S1c, S1d, and S1e tests, respectively.241

Adopting a minimum speed threshold 

of 10 kph (6.2 mph) allows the Agency 

to best achieve its goal to pursue 

harmonization, where reasonable, to 

reduce manufacturer burden and better 

fulfill the BIL’s mandate that NHTSA 

consider the benefits of consistency 

with other U.S. and international rating 

systems. 

The Agency is also selecting 10 kph 

(6.2 mph) as the minimum speed 

threshold because system performance 

at speeds below 10 kph (6.2 mph) does 

not appear to be practical at this time. 

The Agency’s recent research testing for 

model year 2021 and 2022 vehicles 

showed that many vehicles were unable 

to prevent contact with the SV at 10 kph 

(6.2 mph), even though these same 

models achieved acceptable 

performance at incrementally higher test 

speeds (i.e., 20, 30, 40 kph (12.4, 18.6, 

24.9 mph), etc.). This was observed for 

each of the various test conditions and 

lighting specifications. 

NHTSA is establishing a maximum 

speed threshold of 60 kph (37.3 mph), 

as proposed, for nearly all of the test 

conditions adopted herein, with the 

exception of S1d testing conducted in 

darkness. A 60 kph (37.3 mph) upper 

speed limit is generally appropriate for 

several reasons. Adopting this speed for 

the upper limit of the test speed range 

would permit safe test conduct and 

repeatability, as the pedestrian 

surrogates the Agency plans to use for 

testing allow impact speeds of 60 kph 

(37.3 mph). As mentioned above, a 60 

kph (37.3 mph) SV speed is also 

consistent with that prescribed in Euro 

NCAP’s AEB/LSS VRU systems test 

protocol for the comparable AEB test 

conditions (i.e., CPFA, CPNA, CPNCO, 

and CPLA).242 In addition, adopting a 

60 kph (37.3 mph) upper limit for the 

SV speed range allows the Agency to 

mitigate a large portion of the safety 

problem involving pedestrians. Recall 

that nearly 40 percent of all pedestrian 

fatalities and approximately three out of 

four pedestrian injuries occur in areas 

where the posted speed limit is 60 kph 

(37.3 mph) or lower.243

A 60 kph (37.3 mph) maximum speed 

threshold has also proven practical for 

most of the PAEB test condition 

variants. The Agency’s recent model 

year 2021–2022 research testing showed 

that while PAEB performance was 

generally inconsistent across the tested 

fleet, particularly for higher test speeds 

and dark conditions, at least one vehicle 

was able to completely avoid contacting 

the pedestrian mannequin at all test 

speeds from 10 kph (6.2 mph) up to and 

including 50 kph (31.1 mph) and 

exhibited a speed reduction greater than 

50 percent at 60 kph (37.3 mph) for all 

but one of the adopted test condition 


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244 Insurance Institute for Highway Safety (IIHS) 

(January 2024), Pedestrian Autonomous Emergency 

Braking Test Protocol, Version IV. 

variants, S1d in darkness. For the S1d 

dark lighting variant, four vehicles were 

able to prevent contact with the test 

vehicle at all test speeds from the 

minimum test speed of 10 kph (6.2 

mph) up to and including 30 kph (18.6 

mph); however, when tested in darkness 

at 40 kph (24.9 mph), only two of these 

four vehicle models offered a speed 

reduction greater than 50 percent. As 

such, the next incremental test speed, 

50 kph (31.1 mph), was not assessed to 

prevent damage to the test vehicle and 

equipment. 

Given these findings, a 60 kph (37.3 

mph) upper speed limit is practical for 

current NCAP evaluation for all test 

condition variants except for the S1d 

darkness variant. By adopting 60 kph 

(37.3 mph) for the upper bound of the 

SV speed range, the Agency reasons it 

will mitigate as much of the safety 

problem as possible while not 

compromising test repeatability and safe 

test conduct. While NHTSA 

acknowledges that no one vehicle was 

able to provide complete crash 

avoidance for each of the test variants 

adopted herein, test vehicles’ aggregate 

performance for available production 

PAEB systems is not indicative of 

shortcomings in the overall capability of 

PAEB technology. Instead, current 

systems are simply designed to meet a 

lower level of performance. It is 

noteworthy that IIHS’s analogous testing 

for the S1d condition, the perpendicular 

child scenario, is currently conducted at 

20 kph and 40 kph (12.4 mph and 24.9 

mph), whereas the Agency is adopting 

test speeds for daylight testing ranging 

from 10 to 60 kph (6.2 to 37.3 mph) for 

this test condition.244 As such, the 

Agency reasons further improvements 

in PAEB system performance are 

possible as manufacturers optimize 

perception system hardware and 

software to meet the requirements stated 

in this notice. NHTSA observed a 

similar trend with the deployment of 

AEB technology approximately six years 

ago, when performance was inconsistent 

in NCAP for its AEB scenarios. AEB 

systems failed to meet all performance 

levels established for NCAP at that time, 

but AEB performance quickly improved 

as manufacturers updated and improved 

system software. 

For the S1d darkness variant, it is 

appropriate to adopt an upper speed 

threshold of 40 kph (24.9 mph) at this 

time. While no vehicle was able to 

prevent contact with the pedestrian 

mannequin for this test variant during 

NHTSA’s recent research testing at this 

test speed, two vehicle models provided 

a significant speed reduction (i.e., a 

speed reduction greater than 50 percent 

of the initial SV speed). Furthermore, 

the Agency recognizes, as mentioned 

earlier, that this test condition is 

performed by Euro NCAP at 60 kph 

(37.3 mph) at night, albeit with 

overhead lights in addition to the 

vehicle’s lower beam headlamps. 

Therefore, it is practical, given minor 

software changes to improve system 

performance, for future iterations of 

existing systems to prevent contact with 

the pedestrian mannequin at a 40 kph 

(24.9 mph) test speed during S1d 

assessments in dark lighting conditions 

that utilize only vehicles’ lower beam 

headlamps. As systems exhibit 

improved performance during testing, 

the Agency may then consider 

increasing the upper test speed for this 

test variant as part of future updates to 

the program. 

NHTSA acknowledges that there were 

a fair number of commenters who 

asserted that it should perform PAEB 

testing at speeds exceeding 60 kph (37.3 

mph) (i.e., at speeds ranging from 80 

kph (49.7 mph) to 120.7 kph (75 mph)). 

These commenters cited the 

ineffectiveness of current PAEB systems 

at higher speeds as well as pedestrian 

injury and fatality data that shows a 

safety need to curtail pedestrianinvolved crashes at speeds exceeding 

the upper limit proposed by NHTSA. As 

mentioned, NTSB and CAS also 

encouraged NHTSA not to limit 

assessments to lower maximum speed 

thresholds dictated by current (NTSB) 

or average (CAS) system capabilities. 

Instead, these commenters suggested 

that NHTSA set upper test speed limits 

to drive system capabilities to meet 

ideal performance expectations or to 

identify superior performing systems. 

While there is merit to these 

suggestions and underlying rationale, 

NHTSA reasons that, given other 

decisions it is making to increase the 

stringency of its proposal, adopting a 

maximum speed of 60 kph (37.3 mph) 

for the selected PAEB test scenarios is 

appropriate at this time. As detailed 

later, NHTSA has decided to implement 

a testing approach that requires (1) no 

contact with the pedestrian mannequin 

to prevent real-world injuries and (2) no 

repeated trials at a given test speed to 

ensure system robustness. Furthermore, 

a vehicle will not receive credit for 

passing NHTSA’s PAEB test protocol 

unless it is able to meet these 

performance requirements for all test 

speeds across all test conditions for a 

given lighting condition. As evidenced 

in NHTSA’s recent research testing, few 

PAEB systems were able to meet these 

requirements; therefore, it is expected 

that many may not receive PAEB credit 

for several years after the program 

changes take effect. Yet, it is important 

that NCAP provides consumers with 

useful information to guide their 

purchasing decisions. Steps taken to 

further increase the stringency of PAEB 

testing at this time will likely thwart 

this goal. Furthermore, the Agency 

should assess the implications of the 

anticipated changes on overall fleet 

performance to limit the effect of any 

unintended consequences before 

adopting more rigorous requirements. 

For instance, as Toyota noted, system 

intervention at high speeds may impede 

the driver’s response to an impending 

collision. In addition, the Agency 

recognizes that, given PAEB system 

capabilities for the current vehicle fleet, 

increasing test stringency too quickly 

may spur an increase in false positives 

and thus consumer dissatisfaction. 

NHTSA expects that future system 

designs may include the use of long 

range lidar or other technology, which 

should improve overall system 

performance. As the state of technology 

advances, the Agency may consider 

raising the maximum test speed for one 

or more of the PAEB test condition 

variants (e.g., S4c in darkness) as part of 

future program enhancements upon 

conducting additional research to assess 

test feasibility, system advancements, 

and re-evaluation of the safety problem. 

The Agency also recognizes it is not 

feasible to proceed as Toyota suggested 

and select one test speed (or a subgroup 

of speeds, which other respondents also 

suggested) that would be most 

representative of system performance. 

While these alternative approaches may 

improve testing efficiency in one regard, 

since fewer runs would be required, 

they may also hinder it in another. If the 

Agency were to select one 

‘‘representative’’ speed for testing, it 

would choose the highest speed since it 

would generally be expected to be the 

most stringent and the one most likely 

to discern system performance for more 

injurious and fatal pedestrian crashes. 

However, evaluating system 

performance at only the highest test 

speed instead of at an incremental 

progression of speeds places both test 

equipment and the SV at greater risk for 

damage. Damage to test equipment or 

test vehicles not only introduces costly 

repairs but also delays testing. On the 

other hand, incrementally increasing 

speeds should often, though not always, 

reveal performance degeneration at 

more moderate speeds, thus limiting 

overall risk during testing and 

improving test efficiency. NHTSA also 


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95994 Federal Register / Vol. 89, No. 232 / Tuesday, December 3, 2024 / Notices 

245European New Car Assessment Programme 

(Euro NCAP) (December 2023), Test Protocol—AEB/ 

LSS VRU systems, Version 4.5. 

246https://cordis.europa.eu/docs/results/285/ 

285106/final1-aspecss-publishable-final-report2014-10-14-final.pdf at pg. 19. 

247Swanson, E., Foderaro, F., Yanagisawa, M., 

Najm, W. G., & Azeredo, P. (2019, August), 

Statistics of light-vehicle pre-crash scenarios based 

on 2011–2015 national crash data (Report No. DOT 

HS 812 745), Washington, DC: National Highway 

Traffic Safety Administration. 

reasons that conducting several 

additional runs for each test condition 

will have little impact on overall test 

efficiency or burden and seems 

inconsequential when considering the 

benefits ensuing from ensuring system 

robustness. An incremental testing 

approach should adequately ensure that 

PAEB systems which receive NCAP 

credit for passing requirements offer 

equivalent performance (i.e., no contact) 

across a range of speeds, as several 

commenters suggested. This is 

particularly important since 

pedestrians, who lack inherent 

protection from an impacting vehicle, 

may incur injuries and fatalities even at 

low vehicle speeds. However, NHTSA’s 

latest research testing showed that not 

all PAEB systems that provide passing 

performance at higher speeds also 

perform well at lower speeds. As 

mentioned, some vehicles’ systems 

failed to activate at speeds of 10 kph 

(6.2 mph) but prevented SV-topedestrian mannequin contact at many 

higher test speeds, including the highest 

test speed assessed for a particular 

condition. The Agency also asserts that 

an incremental testing approach is 

appropriate for NCAP’s PAEB 

assessments because it aligns with that 

adopted for the program’s AEB tests and 

the testing methodology employed by 

Euro NCAP for its comparable VRU 

testing. Notwithstanding, NHTSA may 

also consider a reduction in the number 

of speed increments in the future, as 

Adasky suggested, if it looks to add test 

scenarios or conditions to the PAEB test 

matrix and fleet performance for PAEB 

systems has generally improved. 

As the Agency did not receive 

comments on the proposed walking and 

running speeds of the pedestrian 

mannequins stipulated for each test 

condition, it will adopt the speeds 

proposed. For the walking adult test 

conditions (S1a, S1b, and S4c) and the 

running child test condition (S1d), 

NHTSA is adopting a pedestrian 

mannequin speed of 5 kph (3.1 mph). 

For the running adult test condition 

(S1e), the pedestrian mannequin speed 

will be 8 kph (4.9 mph), and for the 

standing adult test condition (S4a), the 

pedestrian mannequin will be stationary 

(i.e., 0 kph (0 mph)). These speeds are 

consistent with those used in NHTSA’s 

PAEB characterization study, the 2019 

draft NHTSA PAEB test procedures, and 

Euro NCAP’s AEB/LSS VRU systems 

test protocol for the comparable test 

conditions.245 They were also 

determined to be appropriate for PAEB 

testing based on research conducted by 

Directorate-General for Research and 

Innovation and published in 2014.246

3. PAEB Testing in Darkness—With 

Lower Beams and Use of Advanced 

Lighting Systems; With Upper Beams, in 

Lieu of or in Addition to Lower Beams, 

and With Overhead Lights; Other 

Technologies To Evaluate in Dark 

Lighting Conditions 

To evaluate PAEB performance in 

darkness, NHTSA planned to perform 

all proposed scenarios with the lower 

beam headlamps as the only source of 

illumination. However, if the vehicle is 

equipped with advanced lighting 

features, such as semiautomatic 

headlamp beam switching, adaptive 

driving beam (ADB), and/or high beam 

assist (HBA) headlighting systems, the 

Agency noted that these features would 

be engaged to function during the test as 

well. NHTSA requested comment on 

whether such a testing approach (i.e., a 

lower beam assessment that only allows 

automatic engagement of advanced 

lighting systems) was appropriate or 

whether it should additionally, or 

alternatively, consider testing in 

darkness that would allow manual 

activation of a vehicle’s upper beams. In 

seeking comment on upper beam 

headlamp assessments, NHTSA noted 

that it is not guaranteed that upper beam 

headlamps will be used during realworld nighttime driving since the driver 

may need to manually activate them. 

NHTSA also asked whether it should 

utilize a secondary overhead lighting 

source, such as overhead streetlights, 

during PAEB testing. Overhead lighting 

is common in urban and suburban areas 

but scarcer along rural roads and 

highways. NHTSA notes that Euro 

NCAP’s nighttime PAEB protocol 

specifies the use of overhead lighting for 

scenarios CPNA–25, CPNA–75, 

CPNCO–50, and CPFA–50 (which are 

similar to U.S. NCAP’s S1a, S1c, S1d, 

and S1e, respectively) with the SV’s 

lower beams activated. Euro NCAP’s 

nighttime in-path scenario, the CPLA 

scenario (25 and 50 percent overlaps), 

which is similar to U.S. NCAP’s S4c 

test, is performed with no overhead 

lighting and with the SV’s upper beams 

engaged. As previously mentioned, 

NHTSA performed limited PAEB testing 

in darkness using lower beam 

headlamps and overhead streetlights, 

and the resulting data indicated only a 

slight improvement in PAEB system 

performance with overhead lighting 

compared to no overhead lighting. 

In devising its proposal, NHTSA 

reasoned that testing with the SV’s 

lower beams engaged without overhead 

lights represents the presumed worstcase, real-world scenario, particularly at 

higher test speeds. Conditions such as 

these represented 36 percent of 

pedestrian fatalities, with 39 percent of 

fatalities in pedestrian crashes 

associated with low light conditions 

with overhead lights per FARS data 

from 2011–2015.247 The Agency 

reasoned that PAEB systems that meet 

the performance test specifications 

under dark lighting conditions with no 

overhead lights are likely to meet the 

performance specifications under dark 

lighting conditions with overhead 

lights, effectively addressing both 

conditions. NHTSA believed that 

assessing vehicles in the proposed 

manner (i.e., under dark conditions with 

no overhead lights and with the 

vehicle’s lower beams) would encourage 

vehicle manufacturers to make design 

improvements to address a significant 

portion of crashes that currently result 

in pedestrian fatalities. 

Beyond its current and proposed 

procedures, the Agency also sought 

further comment on (1) other 

technologies in development which may 

mitigate the significant nighttime 

pedestrian crash problem and (2) 

information available for evaluation 

under dark lighting conditions. 

Summary of Comments 

Use of High Beam, Low Beam, and/or 

ADB/Advanced Lighting Features 

Some respondents favored testing 

vehicles in dark lighting conditions 

utilizing lower beams only (i.e., with no 

advanced lighting system enabled), 

regardless of the scenario. Lidar 

Coalition, Velodyne, NYC DOT/NYC 

DCAS, Aptiv, and one individual 

suggested that the theoretical worst-case 

scenario would be the one with the least 

illumination. Lidar Coalition stated that 

this test procedure specification was 

‘‘critical’’ because each technology used 

for detecting pedestrians has its own 

advantages and limitations. The group 

said that these procedures would drive 

the need for updated sensor types that 

achieve good performance across all 

driving conditions, particularly ones in 

which the human eye fails to identify a 

pedestrian. Velodyne provided data to 

support the Agency’s accounting for 

scenarios where current systems 


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underperform; the Governor’s Highway 

Safety Association (GHSA) found that 

75 percent of pedestrian fatalities occur 

at night. NYC DOT/NYC DCAS noted 

that in NHTSA’s testing, vehicles were 

repeatedly able to avoid crashing into 

the pedestrian mannequin while 

utilizing only the vehicle’s lower beams, 

indicating that it is possible to achieve 

this level of performance. Aptiv 

suggested that vehicles should not be 

tested with any advanced lighting 

features enabled because they can be 

disabled by the consumer. In light of 

this, the commenter deduced that 

vehicles would be evaluated on a level 

playing field if no advanced lighting 

systems are enabled. One commenter, 

Vayyar, suggested that NHTSA run a 

test with no headlamp illumination at 

all, stating this will allow NHTSA to 

evaluate how well PAEB sensors work 

in total darkness. 

There were also commenters, 

however, that recommended testing 

vehicles using the vehicle’s lower beams 

along with advanced lighting systems in 

certain instances. Some reasoned that 

advanced lighting systems should only 

be used when they are enabled by 

default or enabled at key-on. CAS, 

Advocates, Tesla, AAA, Uhnder, 

Adasky, and IDIADA suggested this 

approach as a possibility. HATCI 

mentioned that vehicles should be 

tested in their default configurations 

during ADAS testing and that advanced 

lighting systems should be enabled 

during PAEB testing under dark lighting 

conditions. However, the automaker did 

not specifically state that advanced 

lighting systems must be on by default 

to be included in the test protocol. CAS, 

Uhnder, and Adasky stated that 

advanced lighting systems should be 

enabled only if they cannot be disabled 

by the user. They reasoned that it is 

important to evaluate the worst-case 

scenario, which in their opinion is use 

of lower beams with the adaptive 

driving beam/advanced lighting features 

disabled, where possible. Uhnder added 

that drivers often turn off advanced 

features when they can and that drivers 

often do not utilize upper beams 

appropriately while driving. ZF Group 

also shared this assertion. 

Many commenters stated that 

advanced lighting systems should 

always be enabled, regardless of 

whether they are standard or 

automatically enabled by default. 

Advocates, Intel, FCA, BMW, Honda, 

Toyota, ASC, Rivian, Bosch, Subaru, 

Auto Innovators, The League, Vayyar, 

ZF Group, GM, and several individuals 

supported the use of advanced lighting 

systems during PAEB testing in dark 

conditions. BMW suggested that 

separate tests should be conducted with 

lower beams and with the advanced 

lighting systems enabled, adding that 

NHTSA should weight one over the 

other. Alternatively, BMW stated that 

only testing with advanced lighting 

systems for those vehicles equipped 

could lower the testing burden. Honda 

noted that advanced lighting systems 

are meant to work with PAEB systems 

at night and should be enabled to 

capture the system’s intended 

performance. Rivian echoed Honda’s 

sentiment. Subaru and Auto Innovators 

pointed out that ADB is not required to 

function below 32.2 kph (20 mph), so 

tests should begin at this speed. 

Advocates, Tesla, Toyota, Bosch, 

Subaru, Auto Innovators, The League, 

and GM stated that manufacturers may 

be encouraged to include advanced 

lighting systems in their vehicles if they 

are able to be used during PAEB testing 

in dark lighting conditions. Subaru 

suggested that NHTSA offer extra credit 

for vehicles equipped with advanced 

lighting capabilities. IIHS and one 

individual requested that NHTSA focus 

on adding an advanced lighting 

requirement to all new vehicles, citing 

safety benefits. 

For vehicles not equipped with ADB, 

HBA, or other advanced lighting 

technologies, Honda, Rivian, Subaru, 

FCA, and The League expressed that 

NHTSA should assess at least some 

scenarios with the SV’s high beams 

manually activated. Rivian specified 

that high beams should only be engaged 

in dark driving conditions as it is 

unlikely that an SV would be traveling 

in an area without ambient lighting or 

oncoming vehicles with lower beam 

headlamps only. The League and 

Subaru agreed with this reasoning. 

Subaru also mentioned that high beam 

usage more closely compares to HBA or 

ADB activation. FCA suggested that a 

vehicle’s upper beams should be used in 

scenario S4 testing to lessen test burden. 

A few respondents noted that tests 

should be run both with lower and 

upper beams, with IIHS, CAS, and a few 

individuals favoring this strategy. 

However, CAS clarified that only the 

worst-case, lowest-illumination results 

should factor into capability ratings. 

IIHS stated it plans to give higher 

weight to high beam results in vehicles 

with HBA capability for tests in which 

the speed is over the threshold for 

activating HBA. Intel stated that 

vehicles should achieve partial credit if 

they pass with manual high beam 

engagement, thus motivating 

manufacturers to include advanced 

lighting features in their vehicles. ASC 

did not support the use of any 

manually-activated high beams, and 

AAA requested additional data to show 

that drivers use high beam lighting 

frequently before allowing manual high 

beam activation. 

NHTSA also received comments 

regarding headlighting features, 

specifically advanced headlighting 

systems. GM sated that there is an 

opportunity for the Agency to list 

advanced lighting features on NHTSA’s 

website as a method of promoting the 

technology, therefore driving adoption 

into the vehicle fleet. The automaker 

reasoned that there are safety benefits 

associated with ‘‘Auto High Beam,’’ 

noting that the benefits found are at 

least as great as those for LDW, another 

feature that NHTSA has listed for new 

vehicles on its website. GM also noted 

that far-infrared cameras do not have 

associated field effectiveness data at this 

time due to low penetration rate but 

suggested that they still be added to a 

listing of safety features. Honda, Auto 

Innovators, BMW, FSS, TI, and Intel 

agreed that adoption of advanced 

lighting features such as Auto High 

Beam should be incentivized. FSS noted 

that advanced lighting features not only 

improve PAEB performance but also 

eliminate glare from oncoming vehicles, 

improving visibility for other drivers in 

the surrounding area. FSS also referred 

to IIHS’s vehicle lighting ratings and the 

positive effect on nighttime crash rates 

for vehicles earning the group’s ‘‘good’’ 

rating versus a ‘‘poor’’ rating. To 

encourage installation of advanced 

lighting features in the U.S. vehicle 

fleet, BMW and Auto Innovators 

suggested NHTSA provide additional 

credits for vehicles equipped with an 

advanced lighting feature. Texas 

Instruments (TI) recommended that 

advanced lighting features be added to 

NCAP ratings in some capacity but did 

not specify how this should be 

accomplished. MEMA, CR, HMNA, and 

NTSB were among other respondents in 

favor of incorporating lighting for 

improved nighttime pedestrian 

visibility. 

Overhead Lighting 

NHTSA also requested comments on 

overhead lighting for PAEB testing 

under dark lighting conditions. NHTSA 

notes that rural environments tend to be 

darker and without ambient overhead 

lighting, while urban and suburban 

environments are typically more well-lit 

from overhead lights, surrounding 

vehicle headlamp illumination, and 

other various light sources. Some 

commenters reasoned that the lighting 

should match the environment of the 

scenario approximated. MEMA, BMW, 

HATCI, Subaru, and Auto Innovators 

were in favor of having overhead 


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95996 Federal Register / Vol. 89, No. 232 / Tuesday, December 3, 2024 / Notices 

248European New Car Assessment Programme 

(Euro NCAP) (December 2023), Test Protocol—AEB/ 

LSS VRU systems, Version 4.5. See Annex B. 

249Cicchino, J. B (2022, February), Effects of 

automatic emergency braking systems on 

pedestrian crash risk, Insurance Institute for 

Highway Safety, https://www.iihs.org/api/ 

datastoredocument/bibliography/2243. 

lighting for urban and suburban 

scenarios but no overhead lighting for 

scenarios which more closely reflect 

rural encounters. Subaru specified that 

urban/suburban scenarios should have 

overhead lighting of 15 lux to simulate 

street lighting and that lower beams 

should be acceptable in these scenarios. 

In scenarios with no supplemental 

lighting, ADB or HBA would be 

expected to engage if the vehicle was 

equipped with advanced lighting 

features. If the SV does not have 

advanced lighting features, then some 

commenters (MEMA, BMW, HATCI, 

Auto Innovators, and Intel) asserted that 

high beams should be engaged. BMW 

also suggested that high beams should 

be engaged in higher-speed testing 

scenarios (tests with initial test speed at 

50 kph (31.1 mph) or greater). HATCI 

mentioned that high beams should be 

allowed in dark conditions with no 

overhead lighting if high beam usage is 

shown to be common in the field in 

these situations. 

GM suggested that scenarios be 

performed in two conditions: with 

overhead lighting and the use of low 

beams, and without overhead lighting 

and upper beam headlamps or advanced 

lighting features. The automaker 

reasoned that these two conditions 

represent a large portion of real-world 

driving conditions. Bosch, ZF Group, 

AARP, Intel, State Farm, The League, 

and one anonymous individual agreed 

that testing should be performed both 

with overhead lighting as well as in 

dark lighting conditions. The League 

also noted that if overhead lighting is 

shown to improve PAEB performance, 

then street lighting should be more 

widely deployed with the assistance of 

Congress, the U.S. Department of 

Transportation (USDOT), and the 

Federal Highway Administration 

(FHWA). 

Many commenters expressed 

particular interest in the opportunity to 

harmonize with other global consumer 

information programs, with many 

responding to the proposed PAEB 

protocol noting that overhead lighting is 

used in Euro NCAP’s protocol for 

crossing path tests in low ambient light 

conditions.248 Bosch, TI, MEMA, GM, 

HATCI, Auto Innovators, and NSC were 

in favor of harmonizing NHTSA’s NCAP 

PAEB test procedures under dark 

lighting conditions with Euro NCAP’s. 

Tesla supported harmonization with 

IIHS’s then-upcoming PAEB protocol, 

which does not involve the use of 

overhead lighting. IIHS plans to test 

using both lower beam and upper beam 

headlamps. 

One commenter, FCA, only supported 

conducting tests with overhead lighting 

as part of this upgrade. The group stated 

that current PAEB camera technology 

requires illumination to the sides of the 

vehicle and that regulatory restrictions 

prevent headlighting systems from 

achieving this level of illumination on 

their own. It also noted that this 

condition is more severe than Euro 

NCAP’s current protocol. The group 

suggested that the Agency could add 

tests without overhead lighting at a 

future time when technology advances. 

There were also many respondents 

(Lidar Coalition, Velodyne, NACTO, 

Advocates, CAS, Adasky, AAA, IIHS, 

ASC, and three individuals) who 

commented that no overhead lighting 

should be used in PAEB testing. As 

mentioned previously, Lidar Coalition 

supported testing in the darkest realistic 

conditions possible, comments also 

supplied by Velodyne, CAS, and an 

anonymous individual. Further, both 

Velodyne and Lidar Coalition stated that 

testing without supplemental lighting 

would highlight the need for new 

sensors and technologies that will 

‘‘achieve optimal detection’’ of VRUs in 

all road conditions. NACTO urged 

NHTSA to consider the known 

shortcomings of PAEB systems when 

deciding which scenarios and test 

conditions to include in its NCAP test 

procedures, citing an IIHS study 

showing that PAEB systems are less 

effective in dark conditions.249 One 

individual noted that pedestrians are 

often fatally struck by vehicles while 

walking in areas without streetlights 

and suggested that the Agency evaluate 

performance in commonly encountered 

dangerous situations to achieve NCAP’s 

safety goals. Advocates stated it was in 

favor of testing without overhead 

lighting because of the wide array of 

street light types and brightness in the 

U.S., and the increased stringency that 

testing in dark conditions would 

present. Because of the abundance of 

rural and highway roads without 

overhead street lighting, Adasky stated 

that testing should be conducted in zero 

lux conditions. AAA expressed that 

testing with overhead lighting does not 

challenge a PAEB system as much as the 

use of advanced lighting or low beam 

headlamp use does in isolation and 

therefore suggested that the Agency 

conduct tests without supplemental 

lighting, also noting that many 

pedestrians are struck in areas without 

overhead lighting. 

Additional Information Supplied 

Regarding available technology and 

other information, several commenters 

suggested that NHTSA should evaluate 

each technology type currently available 

and, in some cases, investigate the 

effectiveness of each. ASC noted that 

high resolution imaging radar, lidar, and 

thermal imaging cameras are available 

to address nighttime scenarios. NSC 

requested that NHTSA compare camerabased systems with lidar and other 

technologies in both light and dark 

conditions. Rivian acknowledged that 

there are limitations on FCW and PAEB 

technology’s performance currently, 

specifically noting performance during 

dark lighting conditions. The automaker 

advocated for consideration of current 

system capabilities when determining 

NCAP test speeds and scenarios. 

Other commenters offered 

information regarding specific sensor 

types. Tesla noted that infrared cameras 

may aid in pedestrian and animal 

detection in nighttime conditions. 

Vayyar mentioned that these enhanced 

attributes help the system provide 

robust monitoring. Thermal cameras 

were also specifically recommended by 

Adasky and one individual, with both 

respondents touting thermal cameras’ 

abilities to perform in varied lighting 

situations, including nighttime, rain, 

snow, and fog. Both commenters 

claimed that this is because thermal 

cameras do not depend on ambient light 

to operate effectively. The individual 

commenter expressed that they were 

therefore in favor of more challenging 

test conditions since technology exists 

to address them. Adasky also added that 

thermal cameras have a wide field-ofview and longer range, and since even 

high beam lighting can only currently 

illuminate 120 m (393.7 ft.) to 150 m 

(492.1 ft.) ahead of the vehicle, high 

rates of speed require the system to be 

able to identify objects 200 m (656.2 ft.) 

ahead to reduce false positives. Lidar 

Coalition and Velodyne Lidar disagreed, 

opining that thermal cameras have 

limitations of their own: low resolution, 

placement restrictions, and potential to 

miss objects due to blending of separate 

objects’ head characteristics. Instead, 

both groups stated that lidar systems are 

more capable of addressing nighttime 

scenarios because they rely on their own 

light source and have a higher 

resolution than radar. In addition to 

thermal cameras and lidar, Uhnder 

responded that imaging radar is also of 

higher resolution than most radar 

systems used in PAEB applications 

currently and is a promising technology. 


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Federal Register / Vol. 89, No. 232 / Tuesday, December 3, 2024 / Notices 95997 

250Sullivan, John M., Adachi, G., Mefford, Mary 

Lynn, Flannagan, Michael J. (2003, February). HighBeam Headlamp Usage on Unlighted Rural 

Roadways. The University of Michigan 

Transportation Research Institute. https://

deepblue.lib.umich.edu/bitstream/handle/2027.42/ 

55182/UMTRI-2003-2.pdf. 

251https://www.iihs.org/news/detail/few-driversuse-their-high-beams-study-finds (last accessed 11/ 

18/2023). 

252 87 FR 9916. 

TI and Vayyar suggested that fourdimensional (4D) radar systems may 

increase system effectiveness. With 

regard to 4D systems, TI stated that 

‘‘cascading multiple radar sensors 

provides a wider field of view, an 

extended range, and enhanced angle 

resolution to detect static objects.’’ 

ITS suggested that night view assist, 

a system using infrared headlamps, is 

already available in certain vehicle 

models. The vehicle displays a view of 

upcoming obstacles in the instrument 

cluster to give the driver advanced 

notice. ITS favored including the 

technology in safety ratings but also 

reasoned that including this technology 

in NHTSA’s ‘‘recommended 

technologies’’ section would be 

appropriate. 

Response to Comments and Agency 

Decisions 

Details regarding lighting specifics for 

each condition to be tested are included 

in the sections that follow. 

Vehicle Lighting Specifications, 

Including Advanced Lighting Systems 

NHTSA proposed to use the SV’s 

lower beam headlamps during all NCAP 

PAEB testing conducted in the dark and 

to refrain from manually engaging the 

upper beam headlamps. After 

considering comments, this notice 

adopts this plan. NHTSA will also 

prohibit automatic engagement of a 

vehicle’s upper beams by way of 

advanced lighting systems, such as 

ADB, unless such systems cannot be 

deactivated. 

NHTSA acknowledges that, as 

mentioned in the March 2022 RFC 

notice and above, Euro NCAP performs 

its CPLA scenario, which is analogous 

to the Agency’s S4c scenario, using 

upper beam headlamps. FCA supported 

this test specification to lessen test 

burden on manufacturers. Additionally, 

BMW requested that NHTSA manually 

engage upper beam headlamps during 

higher-speed (50 and 60 kph, or 31.1 

and 37.3 mph) PAEB testing conducted 

in the dark. However, previous studies 

have suggested that drivers may not 

manually engage high beam headlamps 

each time they are warranted,250 and 

NHTSA is not aware of definitive data 

available at this time to suggest that 

drivers use them appropriately in the 

field, as Rivian and other commenters 

had suggested. IIHS found that, for 

3,200 isolated vehicles (where other 

vehicles were at least 10 or more 

seconds away), only 18 percent had 

their upper beam headlamps 

engaged.251 At one unlit urban location, 

IIHS data showed that upper beam use 

was less than 1 percent. IIHS also found 

that even on rural roads, drivers used 

their upper beams less than half of the 

time they should have for maximum 

safety, on average. Accordingly, it is 

inappropriate to tie PAEB to a vehicle 

feature that a driver may or may not use 

on a trip. NHTSA agrees with several 

respondents that supporting data would 

be necessary to allow manual high beam 

headlamp usage. 

Similarly, the Agency has also 

decided that advanced lighting systems, 

including ADB, will be disabled during 

NCAP PAEB testing conducted in the 

dark, unless the advanced lighting 

system cannot be deactivated. This 

decision will apply even to those 

systems that are active by default when 

low beam headlamps are first engaged. 

Furthermore, for lighting systems with 

adjustable settings, the vehicle will be 

tested in dark conditions utilizing the 

beam/lighting configuration that is most 

similar to a traditional low beam setting, 

unless the beam/lighting configuration 

is automatically adjusted. 

While NHTSA amended its lighting 

standard, FMVSS No. 108, ‘‘Lamps, 

reflective devices, and associated 

equipment,’’ in 2022 to allow 

installation of ADB headlamps, citing 

the potential to provide safety benefits 

in preventing collisions with 

pedestrians when other vehicles are 

present,252 such systems are not 

required by this Standard, unlike lower 

beam and upper beam headlamps. 

Therefore, NHTSA reasons, as several 

commenters mentioned, that even if an 

ADB system or other advanced lighting 

system were installed on a vehicle, the 

driver may opt not to use it. 

Accordingly, it is most desirable from a 

safety standpoint for NCAP to assess 

those conditions that represent, as Aptiv 

suggested, a theoretical worst-case 

scenario—testing in dark conditions 

with only the vehicle’s lower beam 

engaged. Several commenters expressed 

concern that vehicles will not be 

evaluated equally if advanced lighting 

features are enabled, stating that they 

are akin to upper beam headlamps. In 

the same vein, others suggested that 

NHTSA evaluate PAEB performance 

with upper beam headlamps if 

advanced lighting systems are enabled 

for use in the lower beam tests. The 

Agency recognizes that ADB works by 

automatically switching from the lower 

beam to the upper beam when it is 

deemed appropriate. As such, testing 

PAEB in the dark with ADB (or other 

advanced lighting systems) enabled may 

amount to NHTSA only evaluating 

system performance when the vehicle’s 

upper beam is active. Finally, because 

ADB and other advanced lighting 

systems will not be enabled for NCAP’s 

PAEB testing, commenters’ concerns 

regarding ADB activation speeds are no 

longer applicable. 

Although NHTSA received 

suggestions to conduct testing using 

upper beam headlamps in addition to 

testing using lower beam headlamps, 

the Agency does not see the need to 

increase NCAP test burden at this time. 

A vehicle which performs well in the 

lower-illumination case would be 

expected to also perform well when 

there is more illumination. Notably, 

more vehicle-to-target contact was 

observed during the lower beam PAEB 

research tests than the upper beam tests. 

However, NHTSA also recognizes that, 

in rare cases, vehicles may perform 

better in PAEB testing with the lower 

beams illuminated versus the upper 

beams. The Agency plans to monitor 

PAEB performance under various 

circumstances and will address any 

further needs for additional testing as 

they become apparent. 

While the Agency acknowledges 

Vayyar’s suggestion that NHTSA 

conduct testing with no headlighting 

system illumination under the 

assumption that this would best test the 

sensing system and provide a true 

worst-case evaluation, this is not a 

reasonable use case. In areas 

synonymous with NHTSA’s lighting test 

conditions (i.e., darkness with no 

overhead lighting), failure to turn on 

one’s headlamps should yield such 

limited visibility that the Agency 

reasons drivers will almost certainly 

realize they are not utilizing their lights 

and turn them on. Driving in dark 

conditions without headlamps also 

constitutes a significant and dangerous 

misuse situation. While NHTSA agrees 

there is merit to assessing worst-case 

conditions in many circumstances, the 

Agency also sees benefit in ensuring 

that test cases are also fieldrepresentative use cases. 

Several commenters suggested that 

NHTSA promote the installation of 

advanced lighting systems not only to 

mitigate nighttime pedestrian crashes 

but to improve nighttime visibility in 

general by eliminating glare. GM 

submitted data to show an estimated 22 

percent field benefit from Auto High 


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95998 Federal Register / Vol. 89, No. 232 / Tuesday, December 3, 2024 / Notices 

253https://www.regulations.gov/comment/ 

NHTSA-2021-0002-3856. 

254Cicchino, J.B. (2022, February), Effects of 

automatic emergency braking systems on 

pedestrian crash risk, Insurance Institute for 

Highway Safety, https://www.iihs.org/api/ 

datastoredocument/bibliography/2243. 

255Swanson, E., Foderaro, F., Yanagisawa, M., 

Najm, W.G., & Azeredo, P. (2019, August), Statistics 

of light-vehicle pre-crash scenarios based on 2011– 

2015 national crash data (Report No. DOT HS 812 

745), Washington, DC: National Highway Traffic 

Safety Administration. 

256Ferenchak, N.N., Gutierrez, R.E., & Singleton, 

P.A. (2022), Shedding light on the pedestrian safety 

crisis: An analysis across the injury severity 

spectrum by lighting condition, Traffic Injury 

Prevention, 23:7, 434–439, DOI: 10.1080/ 

15389588.2022.2100362. 

257 Insurance Institute for Highway Safety (IIHS) 

(January 2024), Pedestrian Autonomous Emergency 

Braking Test Protocol, Version IV. 

Beam systems, mitigating nighttime 

pedestrian, cyclist, and animal 

crashes.253 However, as there will be no 

method for assigning extra credit for 

vehicles with added safety features at 

this time, NHTSA will not implement 

multiple commenters’ suggestions to 

offer additional points or credit to 

vehicles equipped with advanced 

lighting systems, nor will the Agency 

allow vehicles to receive partial credit 

for passing with manual upper beam 

usage as suggested by Intel. More 

research is needed to ascertain safety 

benefits associated with night view 

systems. While it is out of scope for 

NHTSA to require advanced lighting 

features on new vehicle models as part 

of this final notice as some commenters 

requested, the Agency has added 

advanced headlighting assessments to 

its long-term NCAP roadmap. 

Overhead Lighting 

NHTSA agrees that unlit roads are 

treacherous for pedestrians. As both 

AAA and an individual commenter 

noted, pedestrians are often fatally 

struck while walking in areas without 

supplemental lighting. For example, 

IIHS found that in 2019, 35 percent of 

pedestrian fatalities occurred in the dark 

with no supplemental lighting 

present,254 which is nearly the same as 

that found by Volpe in its 2011–2015 

data set (36 percent).255 Further, a study 

of California, North Carolina, and Texas 

crashes from 2010–2019 found that 

pedestrians struck in areas without 

street lights were 2.4 times more likely 

to be fatally injured than those struck in 

areas with street lights.256

Based on this, the Agency has decided 

it will conduct all testing under dark 

lighting conditions with no overhead 

lighting present. As previously 

mentioned, the Agency’s testing showed 

only slightly improved performance 

when conducting PAEB tests with 

overhead lighting present versus no 

overhead lighting. Given these findings, 

the Agency asserts it is also least 

burdensome to conduct testing in the 

darkest environmental scenario only. 

NHTSA acknowledges that some 

commenters suggested it match the 

environmental lighting conditions for 

each test to the analogous real-world 

scenario, with overhead lighting used 

for S1 crossing path scenarios, while no 

overhead lighting would be used for S4 

in-path scenarios. Commenters noted 

that Euro NCAP performs its PAEB tests 

in this manner. However, the Agency 

concludes there are several reasons its 

planned testing approach is the most 

appropriate at this time. 

First, environmental lighting 

conditions vary across the U.S. Light 

color (i.e., color temperature), 

uniformity, luminance level, and other 

parameters may differ, even along 

different stretches of the same roadway. 

As Advocates noted, there are also a 

wide variety of streetlight types in use 

on U.S. roadways, making it difficult for 

the Agency to choose one streetlight 

specification that is representative of all 

or most overhead lighting conditions. 

Instead, it is most practical to conduct 

PAEB testing in dark conditions which 

can be more easily replicated. Such 

testing would align with Adasky’s 

assertion that many American roads are 

not lit. 

In addition, the Agency reasons that 

conducting NCAP’s PAEB tests under 

dark lighting conditions may not only 

mitigate pedestrian involvement in 

crashes at night, but also encourage the 

development of more robust sensing and 

detection technologies. Specifically, 

although there are natural limits to the 

human eye’s vision capabilities in dark 

conditions, several commenters 

described various technologies that 

substantially augment a driver’s ability 

to detect objects and pedestrians. The 

commenters noted the benefits of these 

technologies in different conditions, 

including darkness, rain, snow, and fog. 

While the Agency agrees there are 

technologies available to fulfill this 

need, it is inappropriate to promote or 

mandate one sensor technology over 

another, particularly since there are 

advantages and limitations to each, as 

Lidar Coalition stated. Instead, NHTSA 

intends to test the capabilities of the 

system as a whole. This should allow 

vehicle manufacturers the ability to 

address each nighttime scenario as they 

wish and may in turn spur innovation. 

In response to FCA’s suggestion that 

overhead lighting is necessary based on 

the concern that regulatory barriers may 

prevent manufacturers from designing 

headlamps providing sufficient 

illumination to the sides of the vehicle 

so as to perform well in PAEB testing 

under dark lighting conditions, the 

Agency found this not to be the case 

during its research testing series. As 

described earlier, some vehicles were 

able to perform well in most of the 

adopted PAEB tests conducted under 

dark lighting conditions, proving that 

regulations do not restrict system 

designs which are effective. Based on 

this, the knowledge that PAEB is 

generally less effective when driving in 

dark conditions, and the substantial 

percentage of pedestrian fatalities that 

occur in conjunction with a lack of 

street lighting overhead, NHTSA 

concludes it is most appropriate at this 

time to move forward with testing 

without the use of supplemental 

lighting. 

Finally, NHTSA notes that although 

Euro NCAP uses overhead lighting for 

its CPNA, CPNCO, and CPFA testing, 

IIHS does not utilize supplemental 

lighting for any of its nighttime PAEB 

testing. Instead, IIHS requires that test 

site illumination must be below 1 

lux.257

4. Number of Required Trials To Pass 

and Repeat Trials in the Event of 

Contact 

In its March 2022 notice, the Agency 

proposed an evaluation method for 

PAEB similar to that proposed for AEB. 

NHTSA presented a plan to perform one 

trial per test speed, beginning at a 10 

kph (6.2 mph) minimum SV speed. If 

the SV did not contact the pedestrian 

mannequin during this initial trial, the 

test speed would be raised 

incrementally by 10 kph (6.2 mph) until 

a maximum test speed of 60 kph (37.3 

mph) was achieved and evaluated. If the 

SV contacted the pedestrian mannequin 

during an initial trial for a given test 

condition and test speed combination, 

the resulting next steps would depend 

on the relative longitudinal velocity of 

the SV at impact. If the SV’s relative 

longitudinal velocity at impact was less 

than or equal to 50 percent of the SV’s 

initial test speed, then up to four more 

confirmatory tests at the same SV speed 

would be performed. The SV could not 

contact the pedestrian mannequin in 

three or more of the five total tests. 

However, if the SV contacted the 

pedestrian mannequin at a relative 

longitudinal velocity greater than 50 

percent of the SV’s initial speed, testing 

would be discontinued. This is because 

the vehicle would be considered to have 

failed the PAEB test evaluation at this 

test speed and, consequently, the PAEB 

test overall. Noting that 50 percent of 

the minimum test speed (10 kph, or 6.2 


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Federal Register / Vol. 89, No. 232 / Tuesday, December 3, 2024 / Notices 95999 

258 Japan New Car Assessment Program (JNCAP) 

(Revised March 23, 2022), Autonomous Emergency 

Braking System [For Pedestrian Daytime] 

Performance Test Procedure. 

mph) is 5 kph (3.1 mph) and 50 percent 

of the maximum speed possible (60 kph, 

or 37.3 mph) is 30 kph (18.6 mph), 

NHTSA requested comments on 

whether a 50 percent limit on the 

maximum relative impact velocity was 

an appropriate threshold to establish at 

which additional testing (i.e., repeat 

trials) would be conducted for the 

proposed range of test speeds. 

Given the large number of PAEB test 

conditions proposed for adoption (i.e., 

eight conditions covering multiple test 

speeds and lighting specifications), 

NHTSA noted that its proposed 

approach to reduce the number of test 

trials required at a given test speed from 

those specified in the original draft 2019 

PAEB test procedure was a reasonable 

attempt to reduce test burden. The 

Agency believed that assessing PAEB 

system performance over subsequent 

incremental trials and for multiple 

repeated trials in instances where a 

vehicle is unable to meet the ‘‘no 

contact’’ performance requirement in 

the initial valid trial for a particular 

combination of test condition and speed 

would best integrate program efficiency 

while still ensuring system robustness. 

In addition to seeking comments on 

its proposed assessment approach, 

NHTSA also sought comment on 

whether it should instead pursue an 

alternative approach, such as 

conducting multiple trials for each test 

condition and speed combination 

regardless of whether the ‘‘no contact’’ 

performance criterion was met. The 

Agency collected a wide variety of 

comments in response to these 

questions. 

Summary of Comments 

A few commenters, including AAA 

and ASC, agreed with NHTSA’s 

proposed testing approach in its totality. 

Another commenter, Adasky, relayed 

that NHTSA’s plan was sufficient if 

information about any potential test 

failures is made clear to the public. 

However, several commenters suggested 

NHTSA adopt an entirely different 

testing approach. Specifically, MEMA, 

HATCI, Auto Innovators, and Intel 

recommended the Agency employ the 

evaluation method currently utilized by 

Euro NCAP, whereby the Agency would 

accept self-reported performance 

predictions from manufacturers and 

then randomly select scenarios and test 

speeds to verify vehicle performance. 

Intel further commented that if the 

results of a spot-check test match the 

manufacturer’s results, then the test 

would be accepted (and points could be 

awarded based on performance), but if 

the results differed between the 

manufacturer’s data and NHTSA’s, then 

two additional tests would be 

performed. If two of the three trials did 

not produce the manufacturer’s 

predicted results, the company 

suggested partial credit could be given, 

and a correction factor could be applied. 

The commenters noted this method of 

evaluation would achieve the desired 

result of reducing the test burden on 

NHTSA labs. 

One commenter, CAS, stated the 

performance criteria proposed by the 

Agency could be more stringent. The 

organization explained that systems 

offering no contact performance for five 

of five tests ‘‘provide only 86% 

reliability with 50% confidence.’’ 

Accordingly, CAS opined additional 

tests should only be allowed after 

pedestrian mannequin contact if the 

manufacturer changed the vehicle’s 

configuration in response to the impact. 

Under CAS’s plan, follow-up tests 

would be conducted, and the 

configuration would be retrofitted to 

previously assembled units and applied 

to all new units moving forward, similar 

to the process for a running change in 

crashworthiness NCAP. 

Overall, most commenters agreed 

with the Agency’s approach, in part, but 

suggested an alternative number of trials 

or maximum speed threshold would be 

more appropriate. 

Number of Test Trials/Repeat Trials 

In relation to number of test trial and 

repeat trials, several commenters stated 

the Agency should adopt an alternative 

number of test trials to assess each test 

speed. DRI and Subaru were two such 

commenters, with both stating at least 

two trials should always be completed. 

DRI stated if the first trial ended in a 

contact with an SV impact speed of 50 

percent of the initial speed or greater, a 

full set of five trials would be 

completed. However, if the SV avoided 

the pedestrian mannequin or impacted 

at less than 50 percent of the initial 

speed, one confirmatory repeat trial 

would be conducted. DRI explained if 

the results of the confirmatory trial were 

the same as the initial trial, then that 

scenario/speed would be complete. 

However, if the results differed, then 

three more trials would be conducted 

for a total of five trials. DRI explained 

this approach may potentially identify 

vehicles that inconsistently detect 

pedestrians and would eliminate ‘‘luck 

of the draw’’ results. The laboratory also 

noted anecdotal evidence from its 

testing experience suggesting there may 

be vehicles which cannot reliably detect 

pedestrians, but they perform very well 

otherwise. Subaru suggested that 

NHTSA harmonize with JNCAP’s 

method of testing, which entails 

running three trials for each vehicle 

speed. Subaru stated trials at a given SV 

speed could be stopped at two if the 

vehicle avoided contact twice in a row 

or if the speed reduction rate was the 

same twice in a row.258

Honda agreed with DRI that five trials 

should be performed if the SV contacts 

the pedestrian mannequin at 50 percent 

or greater of the initial speed. TRC 

expressed that three total trials would 

be sufficient, with only one failed run 

permitted. Auto Innovators opined 

multiple trials (i.e., for a three-out-offive passing criterion) would be needed 

if a no-contact criterion is established 

since the Agency’s research data 

showed that several vehicles had 

contact for one run but were able to 

avoid making contact for three out of 

five runs. An individual commenter 

expressed that seven trials would be 

more appropriate to ensure the systems 

work reliably and to harmonize with 

other ADAS test protocols proposed by 

NHTSA for NCAP. 

Two respondents, Toyota and 

Advocates, suggested that an alternative 

number of trials may be more 

appropriate for PAEB evaluations, 

without providing a specific number. 

Advocates suggested a greater number of 

trials may be appropriate, with the 

consumer group advising NHTSA to set 

stringent pass/fail criteria since realworld situations may vary and are not 

ideal. Advocates urged the Agency to 

take this into account when selecting 

the number of trials for each scenario, 

asserting that NHTSA must be confident 

that the technologies will operate as 

tested. Conversely, Toyota suggested 

that a reduced number of trials may be 

sufficient. The automaker emphasized 

the importance of minimizing the 

amount of testing wherever possible to 

provide timely information to 

consumers. It recommended carefully 

selecting the number of test trials (and 

test conditions) to ensure that enough 

relevant performance information is 

conveyed to interested parties. 

IDIADA reasoned the Agency’s 

approach provided sufficient assurance, 

stating it was a ‘‘good strategy’’ to 

perform one run per test speed for 

multiple speeds and a range of scenarios 

since PAEB systems are robust. 

However, the laboratory did not support 

NHTSA’s testing approach in its 

entirety. As discussed later, IDIADA 

commented that vehicles should 

completely avoid making contact with 

the mannequin target at initial test 


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96000 Federal Register / Vol. 89, No. 232 / Tuesday, December 3, 2024 / Notices 

259Tefft, B.C. (2011). Impact Speed and a 

Pedestrian’s Risk of Severe Injury or Death 

(Technical Report). Washington, DC: AAA 

Foundation for Traffic Safety. 

speeds up to 40 kph (24.9 mph) and 

offer speed reductions of greater than 50 

percent for initial test speeds greater 

than 40 kph (24.9 mph). Like IDIADA, 

HATCI also found NHTSA’s proposed 

approach of one run per speed 

appropriate; however, they opined that 

vehicles should get credit for any passed 

runs up to the point of failure and for 

the speed reduction at failure. GM 

stated the Agency could conduct one 

trial per test speed up to 40 kph (24.9 

mph) or until contact occurs. BMW also 

supported the Agency’s approach of 

performing one run per test condition 

and four additional trials in the case of 

impact if NHTSA employed a nocontact criterion; however, the 

manufacturer preferred an assessment 

approach based on speed reduction. For 

this approach, BMW asserted that any 

impact should be followed by two 

confirmatory trials, with the median 

impact speed of the three trials being 

selected as the true impact speed for 

that scenario/speed. Conversely, Auto 

Innovators suggested that the Agency 

may only have to conduct one trial run 

per test speed if a speed reduction 

approach was adopted. However, Auto 

Innovators seemingly preferred an 

assessment approach requiring three out 

of five passing runs in such instances, 

like it advocated for in the event 

NHTSA adopted a no contact criterion 

(discussed prior). 

Appropriate Maximum Allowable 

Impact Speed for Repeat Trials 

Three groups agreed with NHTSA’s 

proposed allowable maximum impact 

velocity for additional testing: AAA, 

ASC, and HATCI. AAA noted testing 

experience suggests insufficient speed 

reduction in the first trial indicates a 

vehicle is unlikely to perform well in 

subsequent testing. ASC specifically 

stated its support of the 50 percent 

reduction in speed value, because at the 

upper end of the testing range (60 kph 

(37.3 mph)), the maximum allowable 

impact speed for additional test trials 

would be 30 kph (18.6 mph), which is 

lower than the pedestrian impact test 

speeds for crashworthiness pedestrian 

protection tests in Global Technical 

Regulation (GTR) No. 9 (40 kph (24.9 

mph)). 

Other commenters, like MercedesBenz, Honda, Intel, IDIADA, Auto 

Innovators, and GM, objected to an 

assessment approach that discontinued 

testing based on a vehicle’s inability to 

achieve complete crash avoidance for a 

specified test speed. These respondents 

suggested that the full battery of 

required test trials should be conducted 

for the entire speed range regardless of 

complete crash avoidance. More 

specifically, Honda and Intel expressed 

it would be overly stringent to 

discontinue testing when impact speed 

is greater than 50 percent of the initial 

test speed, as was proposed. Honda 

stated that four additional trials should 

be conducted in such instances, and 

Intel recommended that, if an 

incremental approach was adopted, 

NHTSA should continue to run trials at 

least one SV initial speed increment 

higher beyond the speed at which the 

vehicle is considered to fail, as long as 

the vehicle achieves full avoidance in at 

least one trial. Although Subaru 

generally agreed with the upper impact 

speed limit threshold, the automaker 

recommended that instead of 

discontinuing testing for impact speeds 

over 50 percent of the initial test speed, 

NHTSA should review in-house 

manufacturer data to determine whether 

this was an expected outcome. If the 

manufacturer data indicates that 

different performance was expected, 

then Subaru suggested additional trials 

should be executed. 

Auto Innovators also supported 

allowing testing to proceed in the event 

of contact and/or a speed reduction of 

less than 50 percent, suggesting the 

Agency utilize a three-out-of-five 

passing criterion in such instances and 

assign partial credit for vehicles that 

perform well at higher speeds. For lower 

initial test speeds (i.e., less than 40 kph 

(24.9 mph)), the group, along with 

Honda, suggested incremental testing 

should proceed regardless of impact 

speed. Honda expressed this would 

limit the influence of potential variation 

in test conditions and would be 

consistent with approaches used by 

other global NCAPs to determine the 

maximum allowable impact speed. The 

manufacturer explained that Euro NCAP 

discontinues testing when the SV 

impact speed reduction is less than 15 

kph (9.3 mph) for initial test speeds over 

40 kph (24.9 mph), and JNCAP 

discontinues testing if impact speed 

exceeds 40 kph (24.9 mph) over two test 

runs. Auto Innovators asserted some 

vehicles may not achieve full avoidance 

at lower speeds due to sensor viewing 

angles and suggested that NHTSA’s 

proposed method of discontinuing the 

test in this case would unfairly penalize 

a vehicle manufacturer and might not 

convey the system’s full capability. 

Subaru also stated that poor 

performance at lower speeds should not 

automatically disqualify a vehicle from 

earning partial credit for better 

performance at higher speeds. 

Like other commenters, GM 

supported continued testing upon 

contact. The manufacturer cautioned 

that a single failure should not result in 

the full penalty of no credit when there 

is potential test variation introduced at 

higher speeds or with obstructions 

present. GM stated that the pass/fail 

penalty should be applied over the 

entire set of test runs instead of 

individual runs. Alternatively, the 

manufacturer suggested the Agency 

could adopt pass/fail criteria based on a 

minimum nominal speed reduction, an 

approach also supported by Tesla, FCA, 

and Aptiv. FCA and Aptiv noted that a 

50 percent reduction when the initial 

test speed is 40 kph (24.9 mph) or 

greater would be too stringent and 

instead suggested that a more 

appropriate speed reduction to accept 

for these higher initial speeds would be 

20 kph (12.4 mph) since the ensuing 

impact speed would fall below the GTR 

No. 9 crashworthiness test speeds, (40 

kph (24.9 mph)). Aptiv stated their 

comment was based on statistics 

showing pedestrian fatalities and 

injuries are ‘‘greatly reduced’’ below 40 

kph. Along similar lines, assuming 

contact was allowed, the League 

advocated for a maximum impact speed 

of 25.7 kph (16 mph) based on a study 

by the AAA showing the average risk of 

severe injury for a pedestrian struck at 

this speed is 10 percent.259

As with other aspects of the PAEB 

testing protocol, Advocates requested 

NHTSA provide data and analyses to 

support its decisions for test 

specifications, noting the information 

the Agency provides must be sufficient 

for consumers to accurately and reliably 

compare vehicle performance. 

Response to Comments and Agency 

Decisions 

As mentioned previously, NHTSA has 

decided to proceed with adopting a 

testing approach for PAEB that is 

similar to, but not identical to, that 

which the Agency proposed. For each 

test condition, the Agency will increase 

test speeds in 10 kph (6.2 mph) 

increments from the minimum test 

speed to the maximum, conducting one 

trial for each required speed. In the 

event the SV contacts the pedestrian 

mannequin during the initial run for 

any test speed, testing will cease for the 

test condition, respective test scenario, 

and PAEB testing for the particular 

lighting condition overall. Vehicles 

must pass all required trial runs (i.e., 

one per test speed) to receive PAEB 

credit for the relevant lighting condition 

on NHTSA’s website. 


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260Using the binomial distribution to determine 

sample size for a given reliability and confidence 

level, 300 trials would be needed for 99 percent 

reliability with 95 percent confidence. See https:// 

reliabilityanalyticstoolkit.appspot.com/sample_

size. Similarly, 59 trials would be needed for 95 

percent reliability with a 95 percent confidence, 

and 29 trials would be needed for 90 percent 

reliability with 95 percent confidence. Since the 

vehicle tested is randomly purchased or leased from 

dealerships, its performance in the AEB tests is 

based on the performance and manufacturing 

reliability set by the manufacturer. 

Number of Test Trials/Repeat Trials 

Although several commenters 

recommended the Agency perform 

multiple trials (e.g., two, three, five, 

seven, etc.) for each test condition, often 

with the number of recommended trials 

varying based on the initial test speed, 

impact speed, or prior results, NHTSA 

has made the decision to run only one 

valid trial per test condition. This 

decision, which aligns with that 

adopted for AEB testing, is appropriate 

for several reasons. 

First, a testing approach that requires 

one trial run per test condition instead 

of multiple runs allows the Agency to 

limit test burden while also performing 

tests for a greater number of conditions 

that represent real-world crashes 

involving pedestrians. Under the 

Agency’s final PAEB test matrix, 

NHTSA will conduct (at most) 36 test 

trials for testing in daylight conditions 

and 34 trials for the testing in dark 

lighting conditions, for 70 trials total. 

This is far fewer than the number of 

trials that would be required if the 

Agency were to adopt an approach that 

required multiple trials for each of the 

six adopted PAEB test conditions as is 

prescribed for NCAP ADAS testing 

currently. For instance, NCAP’s current 

AEB test procedure requires a minimum 

of five passing trials out of seven 

conducted to pass a given test 

condition, for a total of up to 42 trials 

for a CIB test and up to 56 trials for a 

DBS test. Adopting a similar approach 

for PAEB, as one commenter suggested, 

would require that up to 350 total trials 

be conducted, resulting in a significant 

burden to both vehicle manufacturers 

and NHTSA. Choosing instead to 

conduct one trial per test condition 

creates a test burden more comparable 

to NCAP’s current AEB testing. 

Given this decision, it is not necessary 

to proceed as several commenters 

suggested and select only certain 

scenarios and/or test speeds, whether 

pre-selected or chosen at random, to 

verify system performance. Such an 

approach may limit burden, but it 

would not best ensure system 

functionality or robustness. Likewise, it 

is unnecessary to accept manufacturer 

data and spot-check system performance 

for only certain test condition/speed 

combinations, as several commenters 

suggested. NHTSA reasons that its 

reduced testing approach should ensure 

acceptable system performance across a 

range of real-world conditions without 

sacrificing program integrity. This 

finalized test method of limited trials 

should also allow NHTSA to 

communicate valuable information 

more quickly to consumers, as Toyota 

requested. 

The Agency’s decision to conduct one 

trial per test condition/speed 

combination should also limit consumer 

confusion and better instill confidence 

and reliability in a vehicle’s PAEB 

system. As mentioned earlier for AEB, 

allowing repeated trials in the event of 

contact may mislead consumers into 

thinking that a vehicle’s AEB system 

provides more repeatable, robust 

performance than it does. Providing 

consumers with an assessment of 

system performance that is a single, 

representative sample rather than an 

assessment based on a best three out of 

five approach therefore seems most 

appropriate. And, while Auto 

Innovators contended that vehicle 

performance in the Agency’s research 

tests suggests that multiple runs (i.e., for 

a three-out-of-five passing criterion) are 

necessary if a no-contact criterion is 

adopted, NHTSA disagrees with this 

assertion. Although several vehicles 

made contact in many runs, one vehicle 

afforded complete crash avoidance in 63 

out of the 70 total adopted test 

condition/speed combinations. This 

suggests that consistent, repeatable 

performance is possible for more robust 

PAEB systems, and that any poorer 

performance was something 

manufacturers could remedy. To best 

address the safety need, the Agency 

concludes it should devise passing 

performance thresholds that encourage 

design improvements to match the 

system performance afforded by the best 

fleet performers (i.e., those that provide 

no contact during the first trial run for 

a large number of test conditions) rather 

than to establish a performance 

threshold based on the average or worst 

performers. 

While some commenters expressed 

that the Agency should perform 

multiple trials for each test condition to 

ensure system reliability (albeit often 

with contact permitted), the Agency 

asserts, as it conveyed for AEB, that 

requiring one trial run per test condition 

instead of multiple runs is appropriate 

given its decisions to increment test 

speeds by 10 kph (6.2 mph) from a 

minimum speed to a maximum speed 

(as discussed earlier) and to disallow 

contact (as discussed next) for the PAEB 

tests. NHTSA reasons this approach will 

effectively identify system 

inconsistency and adequately address 

DRI’s concern regarding ‘‘luck of the 

draw’’ results. The Agency’s planned 

incremental testing approach, which 

uses relatively small speed intervals, is 

inherently designed to expose 

unreliable systems and ensure system 

reliability without the need for 

confirmatory runs, as the test laboratory 

suggested. If an inferior system happens 

to succeed at one speed, it will likely 

not continue to be ‘‘lucky’’ for the entire 

test series for a test condition (or for 

subsequent test conditions) as speeds 

are increased and test stringency 

increases. Since a failure of any one run 

at any given speed for any one test 

condition will result in an overall test 

failure for the tested PAEB system in 

that particular lighting condition, this 

approach is sufficient to serve as an 

acceptable gauge of system robustness. 

Furthermore, the slight increase in test 

speed from one trial to the next 

effectively provides the same benefit of 

assuring reliability as multiple runs 

conducted at the same speed. By 

adopting this testing method, consumers 

should feel confident that a vehicle that 

receives PAEB credit on NHTSA’s 

website for a given lighting condition 

will operate consistently during a 

myriad of real-world driving situations 

in which consumers will likely be 

involved, as Advocates had requested. 

Adopting the testing approach of 

conducting one run per test condition is 

viable even though CAS asserted that 

‘‘passing five of five tests provides only 

86% reliability with 50% confidence.’’ 

The Agency notes that while its final 

testing approach may be limited in that 

it does not ensure absolute reliability of 

system performance with 100 percent 

confidence, it is also unreasonable to 

impose the number of runs for each 

PAEB test speed that would be required 

to achieve this level of certainty. The 

test burden for NHTSA would increase 

exponentially.260 While NHTSA could 

alternatively consider conducting a 

significant number of runs (i.e., more 

than 20) at only the highest test speed 

for each test condition (i.e., 40 kph (24.9 

mph) for S1d testing in darkness and 60 

kph (37.3 mph) for all other PAEB test 

conditions in daylight and darkness), as 

the Agency mentioned prior for AEB, it 

would risk imparting additional damage 

to the test vehicle and test equipment in 

addition to test delays if it was to take 

such an approach. As such, NHTSA’s 

planned test method affords the most 

balanced approach to ensure system 

reliability with an acceptable degree of 


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96002 Federal Register / Vol. 89, No. 232 / Tuesday, December 3, 2024 / Notices 

261Swanson, E., Foderaro, F., Yanagisawa, M., 

Najm, W.G., & Azeredo, P. (2019, August), Statistics 

of light-vehicle pre-crash scenarios based on 2011– 

2015 national crash data (Report No. DOT HS 812 

745), Washington, DC: National Highway Traffic 

Safety Administration. 

confidence. Furthermore, as will be 

discussed later, the Agency has adopted 

a criterion of ‘‘no contact,’’ like CAS 

requested, which should further help to 

address the organization’s concerns. 

Maximum Allowable Impact Speed for 

Repeat Trials 

NHTSA originally proposed 

conducting multiple trials and requiring 

a three-out-of-five pass rate for instances 

where the relative longitudinal velocity 

between the SV and pedestrian 

mannequin was less than or equal to 50 

percent of the initial speed of the SV 

during an initial trial at any one test 

speed. However, based on the results 

from the Agency’s recent model year 

2021–2022 PAEB research tests, it is 

now unacceptable to award credit to 

PAEB systems with inferior 

performance that may allow impact 

with pedestrians at some frequency 

when other systems are able to avoid 

contact for most test conditions. To 

maximize safety impact, NHTSA must 

establish performance criteria for testing 

that will ensure AEB system response is 

consistent and repeatable. As such, like 

decisions made for AEB NCAP testing, 

NHTSA will not conduct repeat PAEB 

trials in the event of SV-to-pedestrian 

mannequin contact regardless of the 

relative longitudinal impact velocity 

recorded between the vehicle and the 

pedestrian mannequin at the time of 

impact. Instead, PAEB testing for a 

given lighting condition will cease at 

the first instance of contact. The Agency 

is making this decision while, at the 

same time, acknowledging that many 

commenters supported conducting 

additional PAEB test trials when a 50 

percent speed reduction or less is 

observed in the first trial run or 

subsequent trial runs for a particular test 

speed. 

For example, ASC expressed that a 50 

percent reduction in speed was 

acceptable since the maximum 

allowable impact speed at the highest 

PAEB test speed (60 kph (37.3 mph)) 

would be 30 kph (18.6 mph), and this 

speed is lower than the 40 kph (24.9 

mph) pedestrian impact test speed 

specified for crashworthiness pedestrian 

protection tests in GTR No. 9. However, 

the Agency would be remiss to tolerate 

any amount of vehicle-to-pedestrian 

contact in the PAEB NCAP tests given 

the possibility of serious injury or death 

resulting from low-speed crashes. 

Furthermore, NHTSA agrees with 

AAA’s concerns that vehicles that 

cannot provide complete crash 

avoidance in one trial are unlikely to 

avoid contact in subsequent, higherspeed trials, with the exception of trials 

initiated at 10 kph (6.2 mph). 

Discontinuing follow-up testing for 

these vehicles should limit potential 

damage to the vehicle, pedestrian 

mannequin, and test equipment, thus 

avoiding expensive or time-consuming 

interruptions or repairs during NCAP 

assessments and limiting repeatability 

concerns. For these reasons, the Agency 

also does not see a need to proceed as 

Subaru suggested and conduct repeat 

trials for impact speeds over 50 percent 

of the initial test speed for those 

vehicles exhibiting performance that 

differs from manufacturer data. 

For similar reasons, it is not 

appropriate to adopt an alternative, and 

essentially less stringent, speed 

reduction, like 20 kph (12.4 mph), for 

speeds greater than 40 kph (24.9 mph), 

as suggested by FCA and Aptiv. While 

it is true that the resultant maximum 

impact speed (40 kph (24.9 mph)) 

resulting from the maximum initial test 

speed (60 kph (37.3 mph)) is equivalent 

to the GTR No. 9 crashworthiness test 

speed and the likelihood of being killed 

or seriously injured at impact speeds 

below 40 kph (24.9 mph) is reduced, it 

is not negated; injuries and fatalities 

still occur at impact speeds ranging 

from 20 kph (12.4 mph) to 40 kph (24.9 

mph). NHTSA’s crash data shows that, 

on average, 22 percent of pedestrian 

injuries and 8 percent of pedestrian 

fatalities occur yearly on roads with 

posted speeds 40 kph (24.9 mph) and 

under.261 Likewise, NHTSA does not 

agree with adopting a pass/fail criterion 

based on a minimum nominal speed 

reduction, as GM and several others 

suggested, or a maximum impact speed, 

as the League submitted. Adopting a 

testing approach which accepts a 10 

percent chance a pedestrian may incur 

a severe injury, as the League suggested 

for a 27.5 kph (16 mph) maximum 

impact speed, is objectionable when 

systems capable of producing no 

injuries in the scenarios examined exist 

in today’s fleet. 

The Agency disagrees with the 

assertions of many commenters that it 

would be overly stringent or incomplete 

to discontinue testing upon contact in a 

single run and/or when a specific speed 

reduction was not achieved instead of 

proceeding with incremental testing 

through the full battery of required test 

trials. NHTSA’s main objectives—to 

promote robust PAEB system designs, 

maximize safety potential, and prevent 

damage during testing—are best met by 

implementing a no contact criterion for 

each trial run, as CAS and Adasky 

asserted. This applies even to those runs 

conducted at low initial test speeds. 

NHTSA recognizes that Subaru and 

Auto Innovators objected to 

discontinuing testing when poor 

performance was observed at low initial 

test speeds, with the latter commenter 

contending that such an approach 

would unfairly penalize a vehicle and 

not convey the system’s full capability. 

However, assuring robust performance 

across all speeds is imperative to 

maximize safety, especially considering 

a large number of pedestrian crashes 

occur at similar speeds to those 

adopted. The Agency’s planned testing 

approach (i.e., conducting one trial per 

test condition across a wide range of test 

speeds and scenarios and adopting a no 

contact performance requirement) 

provides a more complete assessment of 

system capability and is the most 

appropriate method to ensure system 

reliability and confidence. Since 

vehicles will not be given multiple 

opportunities to provide passing 

performance but will instead be 

required to perform well on the first try, 

the Agency’s approach should allow 

consumers to feel confident that a 

vehicle that receives PAEB credit for a 

given lighting condition on NHTSA’s 

website will operate consistently in the 

real-world driving situations they will 

likely encounter, as Advocates 

requested. 

The Agency also does not concur with 

GM’s assertion that test variations 

introduced at higher speeds or with 

obstructions present may result in 

questionable test conduct such that it 

would unfairly penalize a vehicle to 

discontinue testing based on a single 

run failure. NHTSA imposes tolerances 

on vehicle and target speeds, 

accelerations, positions, etc. to 

eliminate such concerns. Furthermore, 

it expects that PAEB systems that pass 

the selected tests should offer robust 

overall performance such that slight 

deviations from exact test specifications, 

which will likely be encountered during 

real-world driving, should not result in 

vastly different system performance. For 

this reason, it is appropriate that failure 

in a single trial will result in an overall 

test failure for a given lighting 

condition. Robust system performance 

is needed to ensure safety potential is 

realized. 

NHTSA will conduct PAEB tests in a 

prescribed order for its NCAP testing, 

generally moving from least stringent to 

most stringent, based on the Agency’s 

experience gained during research 

testing. For a given lighting condition, 

PAEB testing will proceed as follows: 

S4c, S4a, S1b, S1a, S1e, S1d. For each 


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condition, testing will begin with an SV 

speed of 10 kph (6.2 mph) and will 

increase incrementally by 10 kph (6.2 

mph) until either (1) the SV fails to fully 

avoid the pedestrian mannequin or (2) 

the SV reaches the maximum test speed 

for that condition. If the SV successfully 

avoids the pedestrian mannequin for a 

full battery of tests under one condition, 

testing will move to the next test 

condition. However, if the SV contacts 

the pedestrian mannequin, testing for 

that condition (as well as all subsequent 

testing for the applicable lighting 

condition) will cease. The Agency 

expects that, by using this approach, 

damage to both the pedestrian 

mannequins as well as to the SVs will 

be minimized, thus limiting costly and 

time-consuming repairs and delays. 

Since NHTSA is proceeding with a 

pass/fail approach designed to provide 

a comprehensive assessment across a 

range of test speeds and multiple test 

conditions with no contact, it does not 

see a need to finalize Intel’s request to 

conduct at least one trial for the 

subsequent speed increment beyond the 

speed at which a vehicle first fails in 

instances where the vehicle achieves 

full avoidance in at least one of the prior 

trials. Such vehicles would fail the 

Agency’s PAEB test for the given 

lighting condition at the first instance of 

contact. This test plan, including the 

order in which test conditions are 

carried out, may be amended should the 

Agency’s assessment method change in 

the future. 

5. No Contact Versus Speed Reduction 

For PAEB performance criteria, 

NHTSA proposed that a vehicle must 

achieve complete crash avoidance (i.e., 

have no contact with the pedestrian 

mannequin) to receive credit for a test 

trial conducted at each specified test 

speed (i.e., 10, 20, 30, 40, 50, and 60 kph 

(6.2, 12.4, 18.6, 24.9, 31.1, and 37.3 

mph)) for each test condition (S1a-e and 

S4a-c). NHTSA believed that this 

approach, used in conjunction with an 

incremental increase in SV speed (as 

discussed earlier), would limit damage 

to the pedestrian mannequin and the SV 

during testing. As an alternative, 

however, the Agency sought comment 

on whether it should require minimum 

speed reductions or specify a maximum 

allowable SV-to-mannequin impact 

speed for any or all proposed test 

conditions (i.e., test condition and 

variant/test speed combination). 

Summary of Comments 

No Contact 

Some commenters agreed with the 

Agency that the no contact criterion was 

appropriate for the proposed PAEB test 

conditions. AAA found the no contact 

criterion unambiguous and 

straightforward, qualities that would be 

helpful in evaluating performance, a 

sentiment echoed by Adasky. The 

League commented that avoiding 

contact is the only way to ensure that 

death or serious injury does not occur. 

The remaining commenters that shared 

this viewpoint commented that, by 

requiring no contact, the Agency would 

insure against real-world, challenging 

situations that are not as controlled as 

NHTSA’s test protocol. CAS, Uhnder, 

ASC, and Adasky mentioned that 

pedestrians in the field are diverse, and 

it would be impossible to ensure the 

public at large’s safety without a no 

contact criterion. As mentioned earlier, 

CAS also asserted that a no contact 

criterion is necessary because ‘‘passing 

five of five tests provides only 86% 

reliability with 50% confidence.’’ From 

a logistical standpoint, TRC noted that 

this would be a welcomed approach 

since the test mannequins and 

equipment could receive significant 

damage during pedestrian testing. 

Specifically, a no-contact criterion 

would alleviate concerns about 

equipment durability, particularly for 

higher-speed (greater than 60 kph (37.3 

mph)) testing. 

No Contact at Low Speeds, Speed 

Reduction at Higher Speeds 

A few groups favored requiring no 

contact for tests with initial test speeds 

of 40 kph (24.9 mph) or less and 

allowing speed reduction for tests with 

initial test speeds above 40 kph (24.9 

mph). These included Aptiv, Advocates, 

IDIADA, GM, and Intel. GM stated that 

the current state of technology does not 

support full avoidance at all speeds but 

that it is currently possible in the 

proposed test conditions up to 40 kph 

(24.9 mph). Beyond 40 kph (24.9 mph), 

GM suggested that the vehicle should be 

evaluated based on the amount of speed 

reduction achieved. Advocates 

acknowledged that no-contact results 

are preferable but noted that speed 

reduction offers meaningful safety 

benefits and should be encouraged at 

higher speeds. The group did not offer 

a speed at which to require speed 

reduction versus no contact but 

encouraged NHTSA to determine an 

appropriate threshold. Advocates 

further stated that vehicles which offer 

a speed reduction benefit should be 

given credit in some form. Aptiv 

suggested that full avoidance could be 

required for more simple conditions 

(e.g., non-obstructed adult crossing), but 

not for more difficult ones (e.g., S1d, 

child obstructed by parked vehicles). 

Intel had similar comments regarding 

test condition S1d, since the child 

becomes visible only 1.4 seconds precollision. The company suggested that 

NHTSA should offer full credit for a 40 

kph (24.9 mph) speed reduction from a 

60 kph (37.3 mph) initial test speed for 

this condition. Further, Intel stated that 

there is a clear safety benefit in reducing 

impact speed by 20 kph (12.4 mph) to 

30 kph (18.6 mph) at initial test speeds 

above 40 kph (24.9 mph). Finally, from 

a logistical standpoint, IDIADA 

mentioned that pedestrian mannequins 

can withstand impacts up to 40 kph 

(24.9 mph) with minimal damage. 

Many commenters reiterated the 

safety benefit that speed reduction can 

offer, with Toyota, BMW, Bosch, Honda, 

IIHS, Mercedes-Benz, GM, Rivian, 

DENSO, Auto Innovators, HATCI, and 

Subaru highlighting the advantages of 

speed reduction in their comments. 

Toyota suggested that NHTSA move 

away from a pass/fail criterion to a 

performance-based metric, which the 

manufacturer suggested may allow 

NHTSA to reduce the number of test 

trials required to evaluate vehicles. The 

automaker also noted that reduction in 

impact speed would be a suitable 

measure of performance to distinguish 

one vehicle from another and 

corresponds to real-world performance 

and injury risk. Toyota noted this 

performance-based metric could also 

drive improvements in system 

capabilities. These sentiments were 

echoed by most of the commenters 

mentioned above. For example, IIHS 

asserted if the Agency requires no 

contact, manufacturers may not equip 

their vehicles with systems that can 

offer injury-mitigating speed reduction, 

or it may lead to more false-positive 

activations. Tesla also echoed IIHS’s 

concern regarding increased false 

positive interventions which pose risks 

of their own as manufacturers attempt to 

identify applicable situations as early as 

possible. The manufacturer went on to 

state that a ‘‘fine-tuned’’ speed 

reduction requirement strikes a balance 

between injury mitigation and reduction 

of false positives in the field. Rivian 

mentioned that by providing credit for 

impact speed reduction, NHTSA may 

encourage manufacturers to invest in 

technologies over time rather than 

abandoning them upfront if they cannot 

achieve the no contact requirement. 

Many others, including Auto 

Innovators, Honda, Mercedes-Benz, and 

Bosch, asserted that any speed 

reduction should be rewarded with 

partial credit. Like Rivian, these 

commenters referred to Euro NCAP’s 

sliding scale method of issuing points 


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for reduced impact speeds. GM also 

backed a sliding scale assessment 

approach based on speed reduction for 

test speeds over 40 kph (24.9 mph), and 

HATCI supported assigning partial 

credit when a vehicle can meet the 

imposed performance requirements for 

only certain test speeds, as well as when 

a vehicle fails to meet the performance 

requirements (i.e., greater than 50 

percent speed reduction) at a specific 

test speed as long as it provides some 

degree of crash mitigation. HATCI 

requested that NHTSA harmonize with 

Euro NCAP’s performance evaluation 

method to the extent possible. DENSO 

suggested that speed reduction be tested 

in a range of conditions and referred 

specifically to evaluations in both Euro 

NCAP and U.N. Regulation No. 152, 

‘‘Uniform provisions concerning the 

approval of motor vehicles with regard 

to the Advanced Emergency Braking 

System (AEBS) for M1 and N1 

vehicles.’’ 

Other Suggestions 

Two commenters offered an 

alternative to speed reduction or nocontact: crash avoidance via steering. ZF 

Group and Intel suggested that the 

Agency should allow manufacturers to 

pass scenarios 4a–c by using avoidance 

maneuvers instead of deceleration. ZF 

Group noted that ESS systems can 

support crash avoidance in various 

longitudinal scenarios. 

Two other commenters, Bosch and 

MEMA, specifically discussed Euro 

NCAP’s method of determining contact 

and impact speed, indicating their 

support for the use of a virtual box 

around the articulated pedestrian 

mannequin to account for the movement 

of the mannequin’s arms and legs, 

similar to that specified in Euro NCAP’s 

AEB VRU test protocol. Both groups 

stated that SV contact or impact speed, 

if any, should be determined based on 

this virtual box. 

Finally, two individuals responded to 

this topic with suggestions to take 

individual vehicle design into account 

when determining contact or speed 

reduction criteria. Specifically, these 

individuals suggested that the Agency 

take vehicle mass into account since 

heavier vehicles traveling at a given 

speed will impart more force to a 

pedestrian than a lighter vehicle would 

at the same speed. 

Response to Comments and Agency 

Decisions 

NHTSA is adopting a ‘‘no contact’’ 

criterion for NCAP’s PAEB performance 

test requirements. The Agency 

recognizes that this decision conflicts 

with the recommendations made by a 

number of commenters, many of which 

supported the benefits of a performance 

criterion based on speed reduction. 

Notably, the respondents reasoned that 

a speed reduction criterion, along with 

a sliding scale method of assessment 

like that used by Euro NCAP, would be 

a more suitable metric to permit 

performance comparisons among 

vehicles and encourage improved 

system capabilities. The Agency, 

however, agrees with respondents 

(including as AAA and Adasky) who 

stated that consumers can more easily 

understand a pass/fail metric like ‘‘no 

contact’’ compared to a criterion based 

on speed reduction. Thus, NHTSA 

reasons this criterion should simplify 

vehicle performance evaluations. 

NHTSA is also of the opinion that 

complete avoidance is likely the result 

that most consumers expect from PAEB 

systems. Further, restricting assignment 

of PAEB credit to only those vehicles 

that offer superior system performance 

will also best assure that future designs 

offer meaningful improvements. 

The Agency does not agree with IIHS 

that vehicle manufacturers may not 

equip their vehicles with PAEB systems 

if NHTSA chooses to adopt a no contact 

performance requirement. For the model 

year 2024 light vehicle fleet, 94 percent 

of vehicles are equipped with standard 

PAEB systems. Based on this, the 

probability that manufacturers of these 

models will remove existing sensors 

used for pedestrian detection or fail to 

improve PAEB system capabilities 

simply because the Agency has adopted 

a stringent performance requirement for 

its voluntary consumer information 

program (i.e., NCAP) seems unlikely. 

Today’s consumers expect technological 

advancements, whether they be related 

to infotainment, safety, autonomous 

driving, or otherwise. Because of this, 

the Agency also doubts other 

manufacturers would abandon pursuit 

of PAEB technology because they are 

unable to achieve a no contact 

performance threshold upfront, as 

Rivian suggested. Instead, as other 

commenters contended, adoption of a 

no contact performance metric will 

likely encourage development of 

superior systems that provide robust 

performance in NHTSA’s testing, a feat 

that is reasonably attainable for vehicles 

in the near future using existing 

technology. In the Agency’s 2021–2022 

research, one vehicle model afforded 

complete crash avoidance in all but 

seven of the test conditions adopted 

herein, and four of the failed trials 

stemmed from failure of the vehicle to 

respond to the mannequin at 10 kph (6.2 

mph). 

Several commenters cited the safety 

benefits inherent to speed reduction as 

a reason to adopt a speed reduction 

performance metric. While there are 

benefits to crash mitigation, there are 

more profound safety benefits afforded 

by PAEB systems that offer complete 

crash avoidance. Specifically, NHTSA 

agrees with the League that requiring 

vehicles to avoid contact with 

pedestrians is the only way to ensure 

that death or serious injury does not 

occur. Additionally, it would not be 

appropriate to adopt a no contact 

criterion for vehicle-to-vehicle testing 

(i.e., AEB) and allow contact for vehicleto-pedestrian testing. A no contact 

requirement is especially important for 

pedestrian impacts since the 

consequences are more likely to be fatal. 

By promoting development of more 

robust PAEB systems capable of much 

higher speed reductions and complete 

crash avoidance, future systems may 

effectively address a larger percentage of 

crashes that cause serious injuries and/ 

or fatalities. 

Like the related discussion earlier for 

AEB, a no contact performance metric 

has implicit benefits for NHTSA and 

manufacturer testing as well. As TRC 

asserted, imposing a no contact criterion 

in lieu of speed reduction better limits 

damage to the test vehicle, pedestrian 

mannequin, and test equipment during 

testing. Although the Agency 

acknowledges IDIADA’s comments that 

mannequins may see ‘‘minimal damage’’ 

at impacts up to 40 kph (24.9 mph), 

contact between the pedestrian 

mannequin and test vehicle at low 

speeds can still cause sensor 

misalignment or test device degradation. 

Since such damage can influence test 

results and generate expensive or timeconsuming delays or repairs to ensure 

repeatable testing, adoption of a no 

contact performance criterion better 

ensures the Agency is able to accurately 

verify manufacturer performance 

assessments in a timely manner. 

A few commenters suggested that a no 

contact performance criterion was 

unreasonable for current vehicles to 

meet, especially at higher test speeds. 

Others suggested that the Agency could 

require full avoidance for certain 

scenarios that they considered simpler 

(e.g., S1a–c and S1e) but not others 

(S1d) that they considered more 

difficult. Some respondents preferred 

that NHTSA adopt a speed reduction 

criterion in lieu of no contact and assign 

partial credit using a sliding scale 

(similar to Euro NCAP) for mitigation 

observed at higher initial test speeds. 

However, as mentioned, several vehicles 

from the current vehicle fleet were able 

to avoid contacting the pedestrian 


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262European New Car Assessment Programme 

(Euro NCAP) (December 2023), Test Protocol—AEB/ 

LSS VRU systems, Version 4.5. 

263Swanson, E., Foderaro, F., Yanagisawa, M., 

Najm, W.G., & Azeredo, P. (2019, August), Statistics 

of light-vehicle pre-crash scenarios based on 2011– 

2015 national crash data (Report No. DOT HS 812 

745), Washington, DC: National Highway Traffic 

Safety Administration. 

264 Driver avoidance maneuver was either 

unknown or not reported for 24 percent of fatal 

pedestrian crashes and 52 percent of passenger 

crashes with injuries. 

mannequin for most of the test 

conditions adopted herein. For instance, 

one vehicle model provided complete 

avoidance in all crossing path scenarios 

except for the S1d test condition in both 

daylight and dark lighting assessments, 

and two vehicle models afforded 

complete avoidance in all daylight inpath scenarios. With minor system 

changes to improve performance, future 

versions of these vehicles would be able 

to pass the failed test conditions, thus 

proving a pass/fail metric is practical. 

Therefore, the Agency sees no need to 

condone inferior system performance by 

allowing contact when it can encourage 

the design and development of robust 

PAEB systems instead. As the 

referenced vehicle models have not 

received an increased number of false 

positive reports compared to other 

models, the Agency further reasons that 

its recent data also show that a no 

contact performance metric can be met 

at higher initial test speeds with no 

increase in false positive rates, which 

was a concern expressed by IIHS and 

Tesla. As mentioned previously for 

AEB, NHTSA plans to continue to use 

check marks to assign credit to vehicles 

that pass the performance test 

requirements adopted for each ADAS 

technology until such time as it 

publishes a notice to finalize a rating 

system for crash avoidance 

technologies. Therefore, it cannot award 

partial credit for speed reductions at 

this time, as a few commenters 

requested. 

As requested by Bosch and MEMA, 

NHTSA is adopting the ‘‘virtual box’’ 

specified in section 3.4.2 of Euro 

NCAP’s AEB VRU test protocol 262 to 

clearly define the area that accounts for 

the movement of the articulating 

pedestrian mannequin’s arms and legs 

when determining contact. This virtual 

box is necessary to enable a fair 

assessment for all tested vehicles. At 

this time, however, NHTSA will not 

permit vehicles to pass NCAP’s PAEB 

testing by utilizing steering to avoid 

impact instead of braking for S4a–c, as 

ZF Group and Intel recommended, or 

any of the other PAEB test conditions 

being adopted. Previously-cited Volpe 

data showed that, for cases where driver 

avoidance maneuver was known, the 

driver made no attempt to avoid the 

crash (e.g., no braking, steering, 

accelerating) for 76 percent of 

pedestrian crashes involving fatalities 

and 70 percent of crashes involving 

injuries.263 264 Accordingly, adopting 

PAEB test requirements that require the 

vehicle to automatically brake in the 

absence of driver input, such as 

steering, is appropriate. This decision 

also aligns with that which the Agency 

has made in response to comments 

received surrounding evasive steering 

for NCAP’s AEB tests. As thoroughly 

discussed previously, such factors as 

vehicle dynamics, traffic conditions, 

and traffic participants all influence the 

safety benefit of a steering avoidance 

maneuver. Steering, when used as an 

avoidance maneuver, may not be as safe 

as in-lane braking, particularly in an 

urban environment. Furthermore, 

allowing vehicles to use ESS during 

NCAP’s PAEB assessments to avoid 

contact with the pedestrian mannequin 

would require the Agency to adopt 

additional tests to assess the 

functionality of ESS itself to prevent 

unintended consequences. While this 

may be considered as part of a later 

update, it will not be incorporated at 

this time. The Agency must first study 

the capabilities and limitations of 

systems meant to support the driver 

during these evasive maneuvers prior to 

incorporating such assessments in its 

NCAP testing. As such, NCAP will 

disable ESS systems prior to PAEB 

testing for those vehicles equipped with 

such systems, thus ensuring fairness for 

all vehicles, as only braking 

performance will be evaluated for all. 

Since NHTSA has decided to impose 

a no-contact performance criterion for 

NCAP’s PAEB testing, it does not see a 

need to create more stringent 

requirements for heavier vehicles 

compared to lighter ones, as two 

respondents recommended. Regardless 

of the vehicle’s mass, all vehicles will 

be required to completely avoid impact 

with the pedestrian mannequin. 

Therefore, the potential difference in the 

imparting force created at impact for 

vehicles of different weights is 

inconsequential. 

Finally, regarding Toyota’s comment 

that adopting a speed reduction 

performance criterion could reduce the 

number of trials necessary for vehicle 

assessments and therefore reduce test 

burden, the Agency’s planned testing 

approach, as previously discussed, 

effectively addresses this concern. 

6. Appropriate Minimum Overall Pass 

Rate for PAEB 

NHTSA proposed to denote vehicles 

that are equipped with a given ADAS 

technology and which meet the 

Agency’s applicable minimum ADAS 

performance requirements with a check 

mark instead of a more detailed sliding 

scale assessment until the publication of 

the final notice for the new ADAS rating 

system. NHTSA requested comments on 

the appropriate number of test 

conditions a vehicle must pass to be 

granted a check mark for PAEB, 

suggesting two-thirds of the total unique 

combinations of test scenarios and test 

speeds (i.e., test conditions) as a 

possible benchmark. 

Summary of Comments 

Several commenters agreed with 

NHTSA’s proposed benchmark. BMW, 

Honda, IDIADA, Intel, Uhnder, and 

Bosch stated that passing results for 

two-thirds of unique combinations 

should be required to attain a check 

mark, but some commenters added 

caveats to their comments. Specifically, 

BMW, Honda, and Bosch preferred 

assessments that took speed reduction 

into account in some manner. BMW 

stated this would allow for a more 

accurate rating of a system and would 

set the Agency up for easier tuning of 

rating scales in the future. Honda stated 

it only agreed to a two-thirds passing 

rate if each individual scenario/speed 

combination took speed reduction into 

account. As mentioned earlier, the 

automaker reasoned that a no-contact 

criterion would be too stringent and not 

give credit to products that offer safety 

benefits. In a similar vein, Bosch 

suggested that any amount of mitigation 

should be rewarded and that vehicles 

should receive partial credit even if they 

do not meet the two-thirds minimum for 

a check mark. 

Auto Innovators did not support the 

two-thirds minimum for credit. 

However, like those mentioned 

previously, the group suggested that 

vehicles offering speed reduction 

should be given credit since they still 

provide a ‘‘reasonable safety benefit.’’ 

Auto Innovators also recommended that 

speed reduction should be used to 

determine pass/fail criteria, or 

alternatively, a sliding scale should be 

used as part of an overall PAEB rating. 

Adasky also referred to a rating system 

in its response to this topic, mentioning 

that the Euro NCAP method of 

weighting each category according to 

real-world factors would be preferred 

since some tests will have a larger target 

population than others. Rivian also 

mentioned it preferred a points-based 


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265S1d will be assessed in the nighttime lighting 

condition from 10 to 40 kph (6.2 to 24.9 mph). 

266For daylight conditions, the aforementioned 

vehicle failed only S1d at test speeds greater than 

50 kph (31.1 mph) and S4a and c at 10 kph (6.2 

mph). Similarly, for dark conditions, the vehicle 

failed only the S1d condition at test speeds greater 

than 40 kph (24.9 mph) and S4a and c at 10 kph 

(6.2 mph). 

PAEB rating system requiring a 

minimum number of points to pass. 

However, Rivian stated if NHTSA were 

to move forward with a scenario-based 

approach, the pass rate should be 

determined based on the complexity of 

each test. The automaker also suggested 

that NHTSA should require a greater 

passing percentage for simpler scenarios 

and a smaller passing percentage for 

more complicated or difficult scenarios. 

Citing the variety of real-world 

encounters that occur between vehicles 

and VRUs, CAS stated the pass rate for 

NHTSA’s PAEB system testing should 

be 100 percent. However, the group 

mentioned that NHTSA could enhance 

the program by adding optional PAEB 

tests or by assessing test performance 

metrics like distance between the 

stopped vehicle and the test target. CAS 

explained this would allow consumers 

to identify strengths in vehicle 

performance rather than lowering the 

bar to give credit to vehicles that cannot 

pass all of NHTSA’s tests. 

Three other groups (Toyota, 

Advocates, and GM) commented on this 

topic but did not provide specific 

acceptable pass rates. As mentioned 

earlier, Toyota urged NHTSA to use 

performance-based criteria wherever 

possible, instead of pass/fail criteria. 

Advocates suggested that the Agency set 

stringent pass/fail criteria given that the 

variety of on-road conditions found in 

the field are not always represented in 

the ideal testing environment. Finally, 

GM noted that NHTSA should strike a 

balance between current PAEB system 

limitations and criteria informed by 

real-world pedestrian crash data to 

maximize potential safety benefit. 

Response to Comments and Agency 

Decisions 

Since the Agency has opted to impose 

a no contact performance criterion for 

PAEB testing, it will not adopt a rating 

system based on speed reduction, as 

many commenters requested. Although 

BMW contended that such a rating 

system would be ‘‘more accurate’’ and 

allow NHTSA to make changes more 

easily to reflect future updates, the 

Agency reasons, as previously 

mentioned, that an assessment based on 

no contact can be more easily 

understood by consumers. Until a crash 

avoidance rating system is developed 

and finalized, those vehicles receiving a 

check mark will have met NHTSA’s 

minimum level of performance, and 

those that do not display a check mark 

will have not. 

In the same vein, NHTSA has decided 

to adopt a pass rate of 100 percent for 

NCAP’s PAEB testing instead of the 

suggested two-thirds (i.e., 67 percent) 

benchmark. This decision aligns with 

the Agency’s choice for AEB testing. 

PAEB systems must achieve passing 

results (i.e., no SV-to-pedestrian 

mannequin contact) in all adopted test 

conditions (i.e., 24 tests in daylight 

conditions and 22 in dark lighting 

conditions for S1—S1a, S1b, S1d, S1e, 

spanning speeds from 10 to 60 kph (6.2 

to 37.3 mph),265 and 12 daylight and 

darkness test conditions (i.e., 24 total) 

for scenario S4—S4a and S4c, spanning 

speeds from 10 to 60 kph (6.2 to 37.3 

mph)) to receive credit for PAEB 

technology for each lighting condition. 

By requiring a 100 percent pass rate, the 

Agency concludes consumers will be 

able to quickly recognize which vehicles 

offer robust, repeatable PAEB system 

performance. 

At this time, as mentioned, the 

Agency has decided to assign credit 

separately for PAEB system performance 

in daylight and dark lighting conditions; 

vehicles will not have to achieve 

passing performance for all 70 tests in 

daylight and dark lighting conditions 

collectively to obtain credit for PAEB 

overall. A vehicle must pass the 36 

required test conditions in daylight to 

obtain credit for PAEB performance in 

daylight and must separately pass the 34 

prescribed test conditions in dark 

lighting conditions to obtain credit for 

PAEB performance in darkness. The 

Agency has decided to evaluate PAEB 

performance in daylight and dark 

lighting conditions separately because 

no one vehicle tested as part of 

NHTSA’s model year 2021–2022 

research passed all test conditions (i.e., 

did not contact the pedestrian 

mannequin) for both daylight and dark 

lighting conditions. However, as 

mentioned, one vehicle exhibited nearly 

passing performance for each of the two 

lighting conditions.266

By assigning credit separately for each 

of the two lighting conditions, the 

Agency’s planned approach offers a 

compromise between the pass rate 

endorsed by several commenters (i.e., 

two-thirds or 67 percent, albeit often 

with a speed reduction performance 

criterion instead of no contact) 

compared to that suggested by CAS (i.e., 

100 percent) for the proposed 70 unique 

PAEB test combinations. A vehicle that 

contacts the pedestrian mannequin for 

any of the required 34 PAEB test 

conditions when tested in the dark will 

not receive credit for PAEB performance 

in darkness; however, that same vehicle 

may still receive credit for PAEB 

performance in daylight if it offers 

complete crash avoidance for the 

required 36 PAEB test conditions when 

tested in the daylight. A vehicle could 

technically fail all 34 test conditions 

required for testing in darkness and still 

receive credit for PAEB in daylight, thus 

permitting an overall effective PAEB 

pass rate of just over 50 percent. 

Therefore, this approach aligns with 

Bosch’s request to award partial credit 

for those vehicles that are not able to 

meet a two-thirds pass rate overall. It 

also provides additional useful 

information to certain groups of 

consumers that may not have otherwise 

been conveyed if the Agency had 

chosen to instead adopt a pass rate of 

100 percent for PAEB testing in both 

daylight and dark lighting, collectively. 

For instance, certain groups of 

consumers that drive primarily at night 

may find separate lighting-specific 

PAEB ratings particularly helpful. 

Likewise, consumers that rarely drive at 

night may not be deterred from 

purchasing a vehicle that does not 

perform well during NCAP’s PAEB 

assessments in darkness. This decision 

also aligns with CAS’s comment that the 

Agency should reward superior 

performance instead of lowering the bar 

so that more vehicles may receive 

credit. Although NHTSA has decided to 

require passing performance in only one 

lighting condition for this NCAP 

upgrade to receive partial credit for 

PAEB, this approach currently seems 

challenging for most vehicles given the 

results of its most recent PAEB research, 

even when considering a reduction in 

test speed for the S1d in dark lighting 

condition. 

Several commenters suggested 

alternative pass rates. Rivian opined 

that, if NHTSA adopted a pass-fail 

performance threshold, the pass rate for 

PAEB systems should be based on test 

complexity (i.e., a vehicle should be 

required to achieve passing performance 

for a greater percentage of test 

conditions for simpler scenarios 

compared to more complicated/difficult 

scenarios). Further, Adasky 

recommended that target populations 

for real-world crashes should dictate the 

weight assigned to each test scenario/ 

condition. GM also suggested that realworld crash data should be considered, 

in addition to current system 

limitations. Although there is merit to 

these suggestions, the Agency agrees 

with Advocates that it should establish 

stringent pass/fail criteria to ensure that 


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267As an example, when the S1d test condition 

was conducted for a model year 2020 Subaru 

Outback traveling at 16 kph, the onset of the FCW 

occurred at 0.92 sec. (FCW on time history plot) and 

automatic braking occurred essentially at the same 

time, at 0.91 sec. (PAEB on time history plot). 

‘‘Final Report of Pedestrian Automatic Emergency 

Braking System Research Testing of a 2020 Subaru 

Outback Premium/LDD,’’ https://

www.regulations.gov/document/NHTSA-2021-0002- 

0002, See: Figure D66. Time History for PAEB Run 

180, S1d, Daytime, 16 kph. 

268The accelerator pedal will be released in a 

timely manner in either instance so as to not 

interfere with, and potentially override, the PAEB 

system, as this could affect test repeatability. 

PAEB systems are robust and perform 

well during variations of the Agency’s 

tested conditions, since the situations 

encountered during real-world driving 

will not always mirror the ideal testing 

environment. As such, only a 100 

percent pass rate for each lighting 

condition ensures the development of 

optimal PAEB system designs. While 

capabilities may be limited for many 

current PAEB systems, as GM suggested, 

the results for one vehicle in the 

Agency’s research testing exemplified 

system potential for future system 

iterations. 

Finally, at this time, the Agency will 

not adopt additional optional PAEB 

tests for extra credit, as CAS requested. 

NHTSA is considering the inclusion of 

other PAEB test scenarios in NCAP at 

some point in the future, such as 

turning scenarios and scenarios for 

bicyclists. These potential scenarios are 

discussed in a later PAEB section of this 

notice. However, the Agency is not 

considering program additions that 

align with CAS’ second request—adding 

performance assessments based on the 

distance between the stopped vehicle 

and the test target. Because 

manufacturers must design PAEB 

systems that perform well in all realworld conditions, not just those 

assessed by NHTSA, the finalized NCAP 

test conditions should not be unduly 

prescriptive. Whether a vehicle stops 

several inches or several feet behind a 

pedestrian mannequin when tested 

seems irrelevant considering the 

outcome (i.e., complete crash 

avoidance) is the same. The Agency 

prefers to encourage manufacturers to 

expend additional resources into 

perfecting performance in all PAEB test 

conditions, both daylight and dark 

lighting conditions, as well as for the 

wide variety of other crash scenarios/ 

conditions that may occur during realworld driving. 

7. PAEB Warning, Including Signal 

Modality and Timing 

NHTSA is adopting the same FCW 

modalities outlined for NCAP’s AEB test 

conditions for the program’s PAEB test 

conditions. Specifically, a vehicle must 

present a forward collision warning to 

the vehicle operator via two sensory 

modalities—auditory and visual—to 

receive credit in each of NCAP’s PAEB 

tests. Similar to AEB, while the Agency 

is requiring a an auditory/visual FCW, 

a vehicle may additionally present a 

haptic signal to warn of an impending 

collision without penalty. Adopting the 

same bimodal alert strategy for PAEB as 

NHTSA adopted for AEB is appropriate 

since standardization should ensure 

consumer familiarity and limit 

confusion. Drivers will be more likely to 

associate a dual-modality FCW with any 

sort of crash-imminent forward collision 

and, as such, should be more likely to 

respond with a timely and evasive 

action to mitigate or, if possible, avoid 

a crash altogether. This is especially 

important for crash-imminent situations 

involving pedestrians since they have 

no intrinsic protection. 

While the Agency will require the 

same dual-modality alert type for 

NCAP’s PAEB tests as it’s requiring for 

the program’s AEB tests, it is making a 

distinction for the timing of the FCW. 

For PAEB testing, the FCW need not be 

issued prior to the onset of automatic 

braking, like was specified for AEB; the 

warning may be issued at any time 

before or during the automatic braking 

event. The Agency is making this 

distinction for PAEB because it 

recognizes the dynamics of some 

pedestrian crashes inherently result in a 

quick succession of events. For these 

crashes, it may be problematic to require 

the warning be followed sequentially by 

automatic braking. This was evidenced 

in the Agency’s 2020 research testing, 

particularly for certain test conditions, 

such as S1d. The Agency’s data showed 

automatic braking occurred nearly 

concurrent with, or prior to, the FCW 

for several of the Agency’s test 

vehicles.267 Yet, many of these vehicles 

avoided contact with the pedestrian 

mannequin. Therefore, NHTSA hesitates 

to require sequential warning and 

braking functionality in order to not 

hinder system response time or alter 

system effectiveness. The Agency also 

does not want to encourage 

requirements that would drive forward 

collision warnings to be issued too early 

in response to potential pedestrian 

impacts since pedestrian movements 

can be unpredictable. Early warnings 

may have unintended consequences and 

lead to an increase in false positive 

activations. While FCWs issued prior to 

the onset of automatic braking are most 

desirable since they will serve to warn 

the driver of an impending crash and 

solicit a response, those issued after the 

onset of automatic braking can also be 

beneficial since they should serve to 

inform the driver that automatic braking 

is ongoing. 

During NCAP’s PAEB tests, NHTSA 

will release the SV’s accelerator (at any 

rate) within 500 ms after (1) issuance of 

the two required FCW signals (i.e., 

auditory and visual), or (2) the onset of 

automatic braking (as defined by the 

instant SV deceleration reaches at least 

0.15g), whichever is sooner.268 In either 

instance, the vehicle can pass a test trial 

if it does not make contact with the 

pedestrian mannequin and both signals 

for the bimodal alert are issued at some 

point prior to or during the braking 

event. While neither modality signal 

will be required prior to the onset of 

PAEB braking, both will be required 

prior to the end of the test for a vehicle 

to receive a passing result. If one or both 

of the signals required for the dualmodality FCW are not issued and the 

vehicle’s PAEB system does not offer 

any automatic braking (as defined by the 

instant SV deceleration reaches at least 

0.15g), in a PAEB test, release of the SV 

accelerator pedal will not be required 

prior to impact with the pedestrian 

mannequin and the vehicle will fail the 

trial run. The driver (or throttle robot) 

will modulate the accelerator to 

maintain a constant speed until the end 

of the test occurs. 

It is reasonable to require that both 

FCW signals be issued before the end of 

the event in the Agency’s PAEB tests 

because, as explained earlier, one of the 

two FCW signals which comprise a 

bimodal alert often serves as a 

secondary, confirmatory indication that 

explains to the driver what the primary 

signal is intended to communicate (i.e., 

a forward crash-imminent situation). 

Therefore, it seems prudent to assume 

these signals would be provided nearly 

concurrently, particularly given the 

dynamics of many pedestrian crashes 

and the limited time for intervention. 

The Agency is aligning other 

decisions for PAEB with those made for 

NCAP’s AEB tests with respect to the 

FCW. NHTSA is not prescribing 

additional requirements for visual or 

auditory warnings (e.g., color, location, 

decibel level, type, etc.) and it is not 

standardizing PAEB warnings at this 

time. 

8. User-Configurable Settings for PAEB 

Tests 

In its March 2022 RFC notice, the 

Agency proposed to test the middle (or 

next latest) FCW and PAEB system 

settings when assessing FCW and PAEB 


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as part of NCAP’s PAEB tests for those 

vehicles that offer multiple timing 

adjustment settings. 

Since NHTSA has decided to evaluate 

FCW in tandem with PAEB (essentially, 

the SV must issue the required FCW 

signals at some point during the braking 

event), and the vehicle must not contact 

the pedestrian mannequin during 

testing, the tested FCW and PAEB 

system settings are important test 

variables. Effectively, to perform well in 

the Agency’s PAEB evaluations, the 

vehicle must issue the FCW and brake 

automatically with sufficient time to 

allow the vehicle to avoid contacting the 

POV. As it decided for NCAP’s AEB 

tests, the Agency will set the timing for 

the FCW and PAEB intervention to the 

middle (or next latest) setting (if 

adjustable) during its PAEB evaluations, 

like that previously shown in Figure 2. 

For FCW or PAEB systems having only 

two settings, the Agency will select the 

later of the two settings and this test 

setting will meet NHTSA’s middle (or 

next latest) FCW/PAEB setting 

requirement. These system setting 

configurations align with Euro NCAP’s 

AEB/LSS VRU systems test protocol. By 

integrating FCW assessments and 

adopting the middle (or next latest) 

system settings, NHTSA expects that 

vehicle manufacturers will inherently 

strive to limit nuisance alerts and PAEB 

activations during real-world driving for 

the timing settings preferred by most 

drivers while also performing well in 

NCAP’s PAEB tests at this preferred 

setting. 

NHTSA is also imposing requirements 

for other system settings during NCAP’s 

PAEB tests. For vehicles that have an 

ESC off switch, NHTSA will keep ESC 

engaged for the duration of the test. For 

vehicles offering regenerative braking, 

the Agency will select the ‘‘off’’ setting, 

or the setting that provides the lowest 

deceleration when the accelerator pedal 

is fully released for those vehicles 

offering multiple regenerative braking 

settings (e.g., less aggressive, nominal, 

more aggressive). This decision, which 

was also made for NCAP’s AEB tests, 

should promote fairness and improve 

test execution, and thus test 

repeatability. NHTSA will also select 

the ‘‘off’’ setting for vehicles equipped 

with a one pedal operation mode in 

instances where those vehicles offer 

selectable settings for modes of 

operation. If one pedal operation cannot 

be disabled (i.e., regenerative braking is 

always enabled and one pedal operation 

cannot be switched ‘‘off’’), the vehicle 

will be tested with the moderate 

deceleration level ensuing from 

accelerator pedal release. For these 

vehicles, like all other vehicles, the 

accelerator pedal will still be fully 

released within 500 ms after the FCW is 

presented or automatic braking (as 

defined earlier) occurs. In line with 

these decisions (and that made 

previously for NCAP’s AEB tests), 

propulsion batteries will be charged at 

80 percent or higher capacity during 

PAEB testing for electric vehicles, as 

performing assessments with a higher 

SOC should limit regenerative braking, 

and thus vehicle deceleration, when the 

accelerator is fully released. 

To receive credit for PAEB, forward 

collision warning and pedestrian 

automatic emergency braking 

technologies (i.e., FCW and PAEB 

systems) must appear ‘Default ON’ 

during each ignition/key cycle. While 

the Agency is not prohibiting a 

disabling function for these technologies 

in its NCAP evaluation, it does not 

expect that the testing requirements 

imposed herein should result in 

reduced consumer satisfaction. Instead, 

NHTSA expects drivers will adjust their 

vehicle’s FCW and PAEB system 

settings to meet their personal 

preferences instead of disengaging the 

system altogether. 

9. Articulated Pedestrian Mannequins 

NHTSA proposed, and sought 

comment on, utilizing modern 

mannequins with moving legs instead of 

the posable pedestrian mannequins 

specified in its 2019 PAEB test 

procedure. The Agency explained that 

the articulating pedestrian mannequins 

are more representative of walking 

pedestrians and expected that more 

realistic targets would encourage 

development of PAEB systems that 

detect, classify, and respond to realworld pedestrians more effectively and 

accurately. NHTSA’s adoption of the 

articulating mannequin would also 

harmonize with Euro NCAP and IIHS, 

fulfilling the BIL’s mandate that NHTSA 

‘‘benefit from harmonization with thirdparty safety rating programs.’’ 

Summary of Comments 

Adoption of the Articulating Mannequin 

Several commenters responding to the 

December 2015 notice favored the 

adoption of the articulating pedestrian 

mannequin, and most of the comments 

received in response to the March 2022 

also favored its adoption and use in 

PAEB testing. Those in favor included 

TRC, MEMA, CAS, GM, The League, 

BMW, Bosch, FCA, Honda, Toyota, 

AAA, ASC, CCD Transportation Task 

Force, Rivian, Auto Innovators, Intel, 

HATCI, ZF Group, IDIADA, and one 

individual. Most of these commenters 

stated that articulating pedestrian 

mannequins are more representative of 

pedestrian gait and should be used. TRC 

noted that articulating pedestrian 

mannequins are the industry standard, a 

sentiment echoed by GM, BMW, FCA, 

Toyota, ASC, Auto Innovators, Intel, 

The League, and HATCI. GM added that 

‘‘the only means of measuring the 

potential added capabilities of [camera/ 

radar] fusion systems, especially in lowlight conditions, is to use the articulated 

pedestrian mannequin.’’ Bosch, Auto 

Innovators, and HATCI noted that 

articulating pedestrian mannequins are 

preferable due to their Doppler spread 

and radar reflectivity characteristics and 

stated the performance measured with 

the static mannequins may not translate 

to real-world benefit. IDIADA also 

specified that radar-based systems 

monitor Doppler frequencies from leg 

movement. Some groups cited PAEB 

systems’ algorithms (AAA) and artificial 

intelligence (FCA) as reason to utilize 

articulated mannequins. Honda added 

the ability to quickly identify a 

pedestrian and react accordingly is 

valuable, especially in situations with 

limited visibility or short reveal times. 

Intel agreed it is necessary for a PAEB 

system to identify pedestrians quickly 

and accurately. Rivian offered that 

accurate identification of pedestrians 

may reduce false positive activations. 

Finally, the League stated there is no 

benefit to adopting an unharmonized, 

fixed mannequin that is less lifelike. 

Though both BMW and Auto 

Innovators agreed that articulating 

pedestrian mannequins should be used 

in PAEB testing, they further requested 

that NHTSA use a black cover for the 

center tube for any PAEB assessments in 

dark lighting conditions the Agency 

may perform. The groups reasoned this 

change will further improve the 

mannequin’s resemblance to an actual 

pedestrian in the dark. TRC also favored 

adoption of the articulating mannequins 

but requested detailed information on 

acceptable pedestrian target movement 

systems. The laboratory specifically 

noted there are currently belt and 

robotic platform systems available. 

Other commenters stated it is 

premature to include the articulated 

mannequins in NCAP and that other 

VRUs should be taken into account. 

Lidar Coalition, Velodyne, and two 

individuals urged NHTSA to account for 

all road users who are not walking, such 

as those in a wheelchair or scooter; 

those standing, pausing, or bending 

down; or those wearing clothing that 

obscures ambulation, such as a dress or 

robe. These commenters raised concern 

that PAEB systems may begin to over 

rely on leg movement as a VRU 

indicator. CCD Transportation Task 


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269Both pedestrian mannequins are manufactured 

by 4activeSystems. 

270 In Euro NCAP’s AEB/LSS VRU Systems test 

protocol, the adult pedestrian mannequin is termed 

the Euro NCAP Pedestrian Target (EPTa) and the 

child pedestrian mannequin is termed the Euro 

NCAP Child Target (EPTc). 

271European Automobile Manufacturers’ 

Association (ACEA), February 2016, ‘‘Articulated 

Pedestrian Target Specification Document,’’ Version 

1.0, available at https://www.acea.auto/publication/ 

articulated-pedestrian-target-acea-specifications/. 

Force agreed that NHTSA should 

consider a variety of VRUs when 

choosing targets, adding that other 

groups may not be accurately 

represented by the pedestrian 

mannequin, such as women, shorter 

adults, and those with darker skin tones. 

Lidar Coalition, Advocates, and 

Velodyne stated that more data is 

needed to ensure the use of the 

articulating pedestrian mannequin will 

not have an adverse effect on these, or 

any other, VRU populations. 

Response to Comments and Agency 

Decisions 

The Agency is adopting the 4activePA 

Adult and 4activePA Child pedestrian 

mannequins for NCAP testing.269

Commenters overwhelmingly favored 

the adoption of articulating, rather than 

static, mannequins for PAEB testing. In 

support of this stance, commenters cited 

harmonization, radar reflectivity 

characteristics, and realistic, lifelike 

movement, among other reasons. These 

pedestrian mannequins, used in 

NHTSA’s research testing and utilized 

by Euro NCAP as part of testing 

conducted per its AEB/LSS VRU 

Systems test protocol,270 provide an 

accurate representation of real-life 

pedestrians, as commenters requested. 

The 4activePA Adult and Child 

mannequins have physical dimensions 

(i.e., size and shape) representative of a 

50th percentile adult male and 7-yearold child, respectively, and are designed 

to produce a realistic response from 

radar, lidar, and camera sensors. Both 

mannequins have features representing 

hair, facial skin, hands, a long-sleeve 

black shirt, long blue pants, and black 

shoes. They also have articulating legs 

synchronized to the forward motion of 

the mannequin, replicate a human-like 

gait, and produce a realistic Micro 

Doppler effect. Unlike the legs of the 

pedestrian mannequin, the arms of the 

mannequins do not move, but are 

posable, and will be posed during 

testing. The 4activePA mannequins are 

also appropriate for NCAP testing 

because they are lightweight with a soft 

exterior to prevent vehicle damage upon 

impact. 

NHTSA will utilize the 4activePA 

Adult mannequin for all PAEB test 

conditions that specify an adult test 

mannequin—S1a, S1b, S1e, S4a, and 

S4c; the 4activePA Child mannequin 

will be utilized for the S1d PAEB test 

condition. While the Agency recognizes 

it could utilize a posable pedestrian 

mannequin for the S4a test condition 

since the mannequin is stationary in 

those tests, NHTSA is adopting instead 

the articulating mannequin for S4a 

testing to promote test efficiency. As 

described later in this section, the 

4activePA Adult mannequin will be 

confined to a standing posture position, 

with the legs at rest (i.e., static), for S4a 

tests. For all other test scenarios 

prescribing the adult mannequin (i.e., 

S1a, S1b, S1e, and S4c), the legs of the 

mannequin will articulate to simulate a 

walking or running motion, as 

appropriate. Similarly, for the S1d 

scenario, the legs of the child 

mannequin will be configured to 

articulate to simulate a running child. 

Since PAEB systems currently on the 

market may utilize camera-, radar-, and/ 

or lidar-based sensors (or some 

combination thereof) to provide 

automatic emergency braking and 

prevent impact with pedestrians, the 

pedestrian test mannequins adopted for 

NCAP’s PAEB testing must meet certain 

specifications to ensure the SV 

recognizes the targets, similar to realworld pedestrians, thus offering realworld benefit. These specifications will 

also help assure test repeatability and 

reproducibility. Accordingly, NHTSA is 

adopting in its test procedures, certain 

specifications provided in several ISO 

standards for color (for camera-based 

sensors), physical dimensions (for 

camera- and lidar-based sensors), 

infrared reflectivity (for lidar-based 

sensors), and radar cross section and leg 

articulation (for radar-based sensors). 

The ISO standards are appropriate 

because they contain a large body of 

research testing to support the test 

devices. In most respects, these 

specifications also harmonize with 

those outlined by Euro NCAP in its 

‘‘Articulated Pedestrian Target 

Specifications’’ document.271 The 

4activePA pedestrian mannequins, as 

manufactured, meet these 

specifications. 

First, the Agency is referencing many, 

but not all, of the specifications in ISO 

19206–2:2018, ‘‘Road vehicles—Test 

devices for target vehicles, vulnerable 

road users and other objects, for 

assessment of active safety functions— 

Part 2: Requirements for pedestrian 

targets.’’ This standard addresses 

specifications for a test mannequin, 

including basic postures and body 

dimensions as well as leg articulation, 

infrared, and radar properties. 

Second, NHTSA is referencing 

sections of ISO 19206–4:2020, ‘‘Road 

vehicles—Test devices for target 

vehicles, vulnerable road users and 

other objects, for assessment of active 

safety functions—Part 4: Requirements 

for bicyclists targets’’ in NCAP’s PAEB 

test procedures. This standard describes 

specifications for bicycle test devices 

representative of adult and child sizes. 

Although NHTSA will not use a bicycle 

test device during NCAP’s PAEB testing 

at this time, this standard is being 

referenced solely because it contains 

sufficient specifications for color (i.e., 

the color of the mannequins’ hair, 

clothes, skin, etc.) for the pedestrian test 

mannequins. 

NHTSA is also referencing in NCAP’s 

PAEB test procedures sections of ISO 

19206–3:2021, ‘‘Test devices for target 

vehicles, vulnerable road users and 

other objects, for assessment of active 

safety functions—Part 3: Requirements 

for passenger vehicle 3D targets.’’ This 

document provides measurement 

procedures for assessing radar crosssection. 

Lastly, NHTSA is referencing ISO 

3668:2017, ‘‘Paints and varnishes— 

Visual comparison of colour of paints,’’ 

in NCAP’s PAEB test procedures. This 

standard, which specifies a method to 

allow the visual comparison of the color 

of paints against a standard, will ensure 

the color of the pedestrian mannequins’ 

hair, torso, arms, and feet are black, the 

color of the legs is blue, etc., as 

prescribed by ISO 19206–4:2020. 

In addition to these requirements, the 

Agency will also require the placement 

of a black cover over the pedestrian 

mannequins’ center vertical pole during 

PAEB assessments in dark lighting 

conditions, as Auto Innovators and 

BMW requested. NHTSA agrees that this 

should further improve the mannequin’s 

resemblance to a real pedestrian. This 

modification should minimize contrast 

with the background and limit 

reflectivity to light sources (e.g., 

headlamps) during testing in dark 

lighting conditions. The radar 

reflectivity requirements prescribed in 

ISO 19206–2:2018 must be met both 

with and without the black cover 

present on the pole. 

Similar to its decision for the GVT, 

NHTSA is not adopting separate 

specifications for the pedestrian 

mannequin carrier system. The carrier 

system controls the speed (where 

applicable) and position (e.g., lateral 

overlap relative to the front of the SV 

and desired contact points) of the 

pedestrian test device. Since these 

variables will be subject to 


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272NHTSA–2019–0102–0011. 

specifications and tolerances prescribed 

for the pedestrian mannequins for each 

test scenario, NHTSA does not see a 

substantial need to specify which carrier 

system must be used to achieve the 

appropriate mannequin kinematics 

during testing. Further, the pedestrian 

mannequins will be assessed while 

mounted on the carrier system per ISO 

19206–2:2018, thus assuring the carrier 

system has a minimal radar crosssection and minimal optical features 

based on the test environment. The 

Agency also notes that, at this time, it 

anticipates using the 4activeSB robotic 

platform for NCAP testing. 

While NHTSA acknowledges the 

stance of a few commenters that the 

Agency should consider adding VRUs 

with different positioning/posture or 

clothing to not overly rely on leg 

movement to prompt system 

intervention, or different dimensions or 

skin tones to offer equivalent protection 

for all pedestrians, the Agency 

concludes the 4activa-PA Adult and 

Child pedestrian mannequins are 

acceptable for this NCAP upgrade. 

Although the Agency reasons it is 

important for PAEB performance 

requirements to ensure real-world safety 

benefits across a broad spectrum of 

pedestrian crash scenarios, it also 

recognizes that, for practical reasons, 

performance requirements cannot 

address every pedestrian crash scenario. 

Notwithstanding, the Agency is 

adopting test scenarios representing a 

walking, running, and standing adult. 

Further, NHTSA is incorporating a test 

scenario designed to simulate real-world 

pedestrian impacts involving children. 

Given this, the Agency expects future 

PAEB systems will effectively address 

pedestrians of various sizes and not rely 

solely on leg articulation for 

functionality. NHTSA will also continue 

to monitor real-world pedestrian crash 

data to ensure the adopted mannequins 

are reasonably sufficient to address the 

crash risks for pedestrians of other sizes, 

such as small adult women, and those 

having alternative postures. This data 

analysis should also allow the Agency 

to determine whether additional VRU 

surrogates or scenarios should be added 

to the Agency’s PAEB test matrix in the 

future as representative test devices 

become available and research proves 

such devices to be robust and reliable 

during testing. Further, as discussed 

later in this notice, the Agency is 

considering adding additional test 

scenarios for bicyclists, motorcyclists, 

etc. in future updates to NCAP. NHTSA 

is also conducting research to assess the 

affect that variations in skin tone and/ 

or clothing may have on PAEB system 

performance. NHTSA will compare 

these results to the referenced ISO 

standard specifications and may 

consider additions or modifications to 

improve the relevance of the Agency’s 

PAEB tests once the research is 

complete. 

10. Additional Test Procedure 

Refinements, Clarifications, and 

Feedback 

NHTSA requested comments on any 

areas of the proposed PAEB test 

procedure that needed clarification or 

further refinement before the Agency 

adopted it for use in NCAP. Various 

comments were received. 

Summary of Comments 

Publication of Draft Test Procedures 

Auto Innovators noted the draft test 

procedures have not been republished 

with changes suggested in response to a 

2019 RFC notice.272 The group 

recommended that NHTSA republish 

the latest version of the procedures for 

comment and review. 

Pedestrian Mannequin Target 

Some commenters stated the 

characteristics of pedestrian mannequin 

target movement, like speed and 

acceleration of the mannequin as it 

moves across the test site, should be 

addressed. One individual stated the 

maximum pedestrian speed did not 

represent runners, as they may approach 

a vehicle’s path more quickly. This 

commenter also noted the Agency could 

factor in safety for the variety of speeds 

at which VRUs travel by also varying 

the target speed. One individual 

commenter noted that seniors tend to 

move at a slower pace and are less likely 

to recover from injuries sustained in a 

vehicle impact, stating that seniors over 

the age of 65 are 35 percent more likely 

to be killed as pedestrians. NSC stated 

that older adults (those 65 and older) 

account for 20 percent of pedestrian 

fatalities. 

For target acceleration, vehicle 

manufacturers expressed logistical 

concerns. Honda, Toyota, and Auto 

Innovators requested the Agency ensure 

the pedestrian mannequin start and 

acceleration distances are adjusted to 

ensure the mannequins move smoothly 

across the surface. Commenters noted if 

the pedestrian mannequin is subject to 

sudden accelerations, it may ‘‘shake,’’ 

and its location and speed may not be 

detected accurately by PAEB systems. 

Toyota provided data to demonstrate 

that for S1b and S1e, a greater 

mannequin acceleration distance is 

needed to achieve a stable velocity. 

Honda recommended S1a-d test 

conditions should have ‘‘PTM Start 

Distance’’ increased from 3.5 m to 4.0 m 

and ‘‘PTM Acceleration Distance’’ 

increased from 0.5 m to 1.0 m. For test 

condition S1e, the manufacturer 

suggested that ‘‘PTM Start Distance’’ 

should be increased from 5.5 m to 6.0 

m and ‘‘PTM Acceleration Distance’’ 

should be increased from 1.0 m to 1.5 

m. Honda and Auto Innovators 

mentioned that this has already been 

addressed in the Euro NCAP and JNCAP 

test procedures. Auto Innovators added 

that pedestrian mannequin motion 

tolerances can accumulate, resulting in 

the target’s final location being farther 

away from its intended location. 

Accordingly, the group stated that the 

pedestrian mannequin motion 

tolerances should be reduced to ensure 

test repeatability, stating that if the 

highest test speed of 60 kph (37.3 mph) 

is adopted, tolerances should align with 

Euro NCAP’s. IDIADA and Honda also 

recommended that NHTSA ensure the 

pedestrian and vehicle travel paths 

intersect at the intended location. 

Regarding false positive testing, GM 

requested clarity on deceleration 

distance in test condition S1f. 

Auto Innovators stated that 

controllability of the freeboard should 

be further investigated. For in-path test 

conditions S4a–c, Auto Innovators 

stated that NHTSA should ensure the 

pedestrian mannequin is properly 

mounted on the pole if the Agency 

intends to test conditions with the 

pedestrian mannequin facing both away 

from and towards the SV. 

Subject Vehicle 

Regarding the movement of the SV, 

Honda suggested that the Agency use an 

accelerator/brake robot to increase the 

robustness of the test procedure. The 

automaker noted that changes like these 

would uphold NCAP’s credibility and 

ensure well-defined safety performance 

information is gathered should the 

Agency collect self-reported data. Auto 

Innovators agreed, requesting that the 

SV be controlled by a steering robot. 

For PAEB testing in dark conditions, 

TRC commented that the ‘‘aimed 

location’’ of the SV’s headlamps may 

need to be documented, further noting 

that IIHS currently records headlight 

aim for some of its work. Advocates 

stated the Agency should verify that the 

advanced headlighting system operates 

automatically. Additionally, Intel and 

ZF Group suggested the test should 

allow sufficient time for the 

headlighting systems to engage and 

switch to upper beams before the test 

begins (or at least 4 seconds TTC). 


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273 88 FR 34366. The final decision notice for the 

NCAP crashworthiness pedestrian protection 

testing program is forthcoming. 

Finally, SEMA stated that NHTSA 

should also test modified vehicles, 

defining modified as ‘‘lifted and 

lowered.’’ SEMA also requested that 

data, including mechanical and 

electronic tolerances, be published by 

the OEM so that modified vehicles’ 

PAEB systems may achieve the same 

performance as a non-modified vehicle’s 

performance. The group stated that such 

vehicle modifications are legal and 

should be accounted for. 

Scenario and Test Condition 

Specifications 

Auto Innovators and GM stressed the 

importance of eliminating other 

artificial light sources that do not 

represent on-road conditions. The 

groups suggested the presence of such 

light may interfere with the intended 

operation of the PAEB system. If the 

artificial light sources cannot be 

removed, GM suggested that tests take 

place in the opposing direction, or, if 

this is not possible, vehicle high beams 

should be engaged to replicate the 

expected driving conditions. These 

commenters also requested alterations 

specific to certain test conditions. Auto 

Innovators stated the Agency should 

align the parked obstacle vehicle 

location in scenario S1d to the Euro 

NCAP condition, and GM requested 

clarity on definitions for pass/fail 

criteria for both false positive (S1f and 

S1g) conditions. 

Velodyne expressed concerns that the 

current test procedures do not include 

enough of the elements of real-world 

driving to effectively evaluate a 

vehicle’s true PAEB performance. The 

company listed ‘‘shadows, unclear or 

unmarked lane lines or road edges, 

curved roadways, irregular route 

geometries, [. . .] irregularities in the 

roadway, cluttered or low contrast 

scenes, overhead objects, or irregular 

object shapes’’ as potential confounding 

factors. Velodyne went on to state the 

shortcomings of cameras and radar in 

effectively informing PAEB systems, 

noting that adding more cameras and 

radar sensors will not be enough to 

address this issue. Velodyne suggested 

lidar will be necessary to address 

challenging real-world conditions such 

as those mentioned above. 

Response to Comments and Agency 

Decisions 

Publication of Draft Test Procedures 

NHTSA acknowledges the prior 

receipt of comments from Auto 

Innovators detailing feedback regarding 

the Agency’s draft PAEB test 

procedures. The Agency has considered 

all comments received and has made 

changes to its PAEB test procedures 

accordingly. These revised PAEB test 

procedures are being published and 

docketed along with this final decision 

notice for use in NCAP testing. 

Pedestrian Mannequin Target 

The Agency is adopting the 

pedestrian speeds proposed in the 

March 2022 RFC notice. NHTSA 

acknowledges requests by respondents 

to make changes to the characteristics of 

the pedestrian mannequin target, 

including accounting for different 

pedestrian speeds based on walking or 

running speed. However, because the 

Agency must be mindful of the test 

burden created by adding additional test 

conditions, it is choosing to keep the 

proposed pedestrian speeds at this time. 

NHTSA notes the pedestrian mannequin 

speeds chosen for NCAP’s PAEB test 

conditions align with those selected by 

Euro NCAP, and thus seem reasonable 

for inclusion in U.S. NCAP. Given the 

variations in test conditions adopted, 

including those for the pedestrian 

mannequin speed (i.e., walking, 

running, and stationary), the Agency 

expects that the prescribed pedestrian 

mannequin target speeds will mitigate 

crashes for pedestrians travelling faster 

or slower than the target speed. Realworld pedestrian crashes that PAEB 

does not completely prevent may also 

be further mitigated by NCAP’s 

forthcoming crashworthiness pedestrian 

protection testing program.273

Further, NHTSA shares similar 

concerns as those expressed by 

commenters relating to pedestrian target 

acceleration, such as potential 

mannequin instability caused by 

inadequate starting and acceleration 

distances already observed and 

addressed by other global testing 

entities. Specifically, the Agency has 

observed that when the pedestrian 

mannequin begins to move, the 

mannequin tends to sway and oscillate 

for some time before gaining stability. 

Additionally, the Agency has found that 

sudden acceleration results in 

inconsistent pedestrian mannequin 

motion. Based on these concerns and 

observations, NHTSA will adopt 

amended starting and acceleration 

distances for its NCAP PAEB test 

procedures. For test conditions S1a–d, 

the pedestrian mannequin’s starting 

distance will be 4.0 ± 0.1 m (13.1 ± 0.3 

ft.) from the SV’s intended travel path. 

For test condition S1e, the pedestrian 

mannequin’s starting distance will be 

6.0 ± 0.1 m (19.7 ± 0.3 ft.) from the 

intended travel path. For all conditions, 

the pedestrian mannequin’s acceleration 

distance will be 1.5 m (4.9 ft.). These 

changes should increase repeatability 

and accuracy of PAEB system testing. 

Apart from the crossing path 

acceleration distance specification, 

these specifications also promote 

harmonization, as they are aligned with 

Euro NCAP’s pedestrian mannequin 

starting and acceleration distances. 

NHTSA will also provide additional 

clarity on the deceleration distance for 

condition S1f if and when it chooses to 

adopt this test condition for NCAP. 

NHTSA will adopt a pedestrian 

mannequin target speed tolerance of 0.4 

kph (± 0.2 mph) for pedestrian 

mannequin motion tolerance. Despite 

commenter concern regarding tolerances 

being too wide and the pedestrian 

target’s final location being inconsistent, 

particularly at higher speeds, the 

Agency’s experience through its 

research testing to date is that this 

amount of tolerance is consistently 

achievable and provides a high-level of 

repeatability. 

Finally, because the Agency plans to 

adopt only the S4a and S4c test 

conditions, which both specify that the 

dummy face away from the vehicle 

instead of towards the vehicle as is 

required for the S4b condition, there is 

a decreased likelihood that the 

pedestrian mannequin will be 

improperly installed on the pole since 

there will be no need to switch the 

orientation of the pole during testing. 

Having said this, test laboratories will 

be expected to inspect their equipment 

prior to performing evaluations and to 

verify that the test setup is valid. 

Subject Vehicle 

Repeatability of the SV’s movements 

throughout the testing series was of 

concern to some commenters. A few 

suggested that either accelerator/brake 

(Honda) or steering (Auto Innovators) 

robots should be utilized. As with the 

AEB tests described earlier, steering and 

throttle requirements are specified; a 

test will be considered valid if these 

requirements are met. Thus, the Agency 

declines to require the use of throttle or 

steering robots at this time to conduct 

testing according to NCAP protocol. 

However, they may be used by 

laboratories or manufacturers if desired. 

NHTSA agrees with Intel and ZF 

Group’s concern that the PAEB testing 

procedure for testing in dark conditions 

should allow time for any advanced 

lighting feature(s) that cannot be 

disabled to engage prior to the official 

start of the test. NHTSA will ensure that 

advanced lighting feature(s) engage 

automatically, if appropriate, and will 


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274 87 FR 9916. 

275American Automobile Association (2019, 

October), Automatic emergency braking with 

pedestrian detection, https://www.aaa.com/AAA/ 

common/aar/files/Research-Report-PedestrianDetection.pdf. 

276Cicchino, J. B. (2022, February), Effects of 

automatic emergency braking systems on 

allow sufficient time prior to the 

vehicle’s encounter with the pedestrian 

mannequin for the automatic 

engagement to occur. It is also 

reasonable to measure vehicles’ 

headlamp aim angles and record these 

prior to testing, as TRC requested. 

However, the Agency will not alter the 

aim of vehicles’ headlamps to align with 

manufacturer instructions prior to 

conducting PAEB tests. NHTSA asserts 

vehicle headlamps should be tested as 

received from the dealer for NCAP 

testing, since it is unlikely vehicle 

owners will adjust the aim of their 

headlamps prior to driving. Thus, 

maintaining factory settings should 

ensure more realistic testing. 

The Agency is not adopting the 

testing of modified vehicles at this time, 

as suggested by SEMA. NCAP’s test 

methodology involves the evaluation of 

production-level vehicles available 

directly from the manufacturer, and any 

modified vehicle may not receive 

similar NCAP results, whether tested for 

crashworthiness or crash avoidance. 

Given the variety of legal modifications 

that may be completed in an aftermarket 

setting, it is not practicable to evaluate 

vehicles with modifications. Further, 

generating this information would be a 

significant burden to vehicle 

manufacturers. 

Scenario and Test Condition 

Specifications 

NHTSA finds validity in the 

unspecified artificial light source 

concerns raised by GM and Auto 

Innovators. As the Agency seeks to 

replicate challenging real-world 

scenarios while also offering repeatable 

test conditions, it has decided that the 

test procedure for darkness PAEB 

testing will specify the ambient 

illumination at the test site must be no 

greater than 0.2 lux. This value 

approximates roadway lighting in dark 

conditions without direct overhead 

lighting with moonlight and low levels 

of indirect light from other sources, 

such as reflected light from buildings 

and signage. Additionally, an 

illumination level of 0.2 lux mirrors the 

level specified in the test procedures for 

the recently issued final rule for 

adaptive driving beams.274 This 

darkness level accounts for the effect 

ambient light has on AEB performance, 

particularly for camera-based systems, 

and should ensure robust performance 

of all AEB systems, regardless of sensor 

type. Also, NHTSA will not perform 

tests where the SV is driving toward the 

moon such that the horizontal angle 

between the moon and a vertical plane 

containing the centerline of the SV is 

less than 25 degrees and the lunar 

elevation angle is less than 15 degrees. 

By incorporating these specifications, 

the Agency sees no need to allow 

manual high beam usage, as GM 

requested. 

Auto Innovators suggested the Agency 

align the parked obstacle vehicle 

location in test condition S1d to the 

applicable specifications prescribed for 

Euro NCAP’s comparable CPNCO test 

condition. The Agency confirms that 

NHTSA’s S1d parked obstacle vehicle 

location aligns with Euro NCAP’s 

CPNCO specification. 

In response to GM’s request that the 

Agency clarify the pass/fail criteria for 

both false positive (S1f and S1g) test 

conditions, appropriate specification 

will be provided if and when the 

Agency chooses to adopt these test 

conditions for NCAP. 

Finally, while NHTSA acknowledges 

Velodyne’s assertion that its current 

PAEB test procedures do not encompass 

all aspects of real-world driving, given 

the number of test conditions and 

variants included in NCAP’s PAEB test 

matrix, the Agency concludes the 

published test procedures are sufficient 

to gauge overall PAEB system 

performance. NHTSA notes it must 

balance attempts to ensure system 

robustness with increased test burden. 

NHTSA may consider adopting 

additional test conditions or variants in 

the future encompassing one or more of 

the elements the commenter mentioned 

if real-world data identifies a significant 

need. 

11. Adding Test Scenarios S2 and S3 

The Agency’s 2019 PAEB test 

procedure does not include CAMP 

scenario S2 (vehicle turning right and a 

pedestrian crossing the road) or CAMP 

scenario S3 (vehicle turning left and a 

pedestrian crossing the road), both of 

which are defined earlier in this final 

notice. In response to the December 

2015 RFC notice, several commenters 

stated that addressing these scenarios 

with available technology may generate 

a significant number of false positive 

detections. These false detections could 

have the unintended consequences of 

causing hazardous situations (e.g., 

unexpected sudden braking while 

turning in traffic) that could lead drivers 

to disable their PAEB systems or 

possibly lead to an increase in rear-end 

collisions. The commenters explained 

that the S2 and S3 test scenarios require 

more sophisticated algorithms as well as 

more robust test methodologies than 

those required for scenarios S1 and S4. 

However, ZF Group mentioned that 

ADAS sensors designed to meet Euro 

NCAP’s Vulnerable Road Users test 

procedures would have increased fieldsof-view, which should improve their 

effectiveness in turning scenarios. Other 

commenters stated that the articulating 

mannequins may not be representative 

of a real human for all sensing 

technologies in turning scenarios. Most 

commenters found it more appropriate 

to focus on the scenarios affording the 

most significant safety benefits first—S1 

and S4, and stated that adding the S2 

and S3 scenarios would be more 

practical when the technology matures. 

NHTSA committed to continuing PAEB 

system evaluations in its March 2022 

RFC notice to determine the feasibility 

of including S2 or S3 scenarios as 

technological advancements are made. 

Earlier in this notice, the Agency 

stated it did not conduct the S2 and S3 

test scenarios as part of its PAEB 

characterization study and did not 

propose these test scenarios for 

inclusion in its current proposal to 

update NCAP. NHTSA agreed with the 

comments mentioned previously that 

most vehicles in the U.S. fleet are not 

currently equipped with sensing 

systems capable of detecting pedestrians 

while a vehicle is turning (i.e., those 

situations represented by S2 and S3 test 

scenarios), as they do not have the 

necessary field-of-view. AAA conducted 

PAEB tests, including an S2 scenario 

where the vehicle is turning right with 

an adult pedestrian crossing.275 In 

AAA’s testing, the PAEB systems for 

four tested model year 2019 vehicles did 

not react to the test targets during a 

testing scenario similar to NHTSA’s S2 

scenario described above, resulting in 

all test vehicles colliding with the 

pedestrian mannequin target. These 

systems performed better in a scenario 

similar to NHTSA’s S1 scenario, 

however. In that testing, the vehicles 

avoided a collision with the pedestrian 

mannequin target 40 percent of the time 

at a 32.2 kph (20 mph) test speed and 

nearly all the time at a 48.3 kph (30 

mph) test speed. Further, in its recent 

study on PAEB system effectiveness, 

IIHS found that while AEB with 

pedestrian detection was associated 

with significant reductions in 

pedestrian crash risk (approximately 27 

percent) and pedestrian injury crash risk 

(approximately 30 percent), no evidence 

suggested that existing systems were 

effective while the PAEB-equipped 

vehicle was turning.276 Thus, it was 


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pedestrian crash risk, Insurance Institute for 

Highway Safety, https://www.iihs.org/api/ 

datastoredocument/bibliography/2243. 

277Hu, W. and J.B. Cicchino. (2022, July), 

Relationship of pedestrian crash types and 

passenger vehicle types, Insurance Institute for 

Highway Safety. 

278Carpenter, M.G., Moury, M.T., Skvarce, J.R., 

Struck, M. Zwicky, T.D., & Kiger, S.M. (2014, June), 

Objective tests for forward looking pedestrian crash 

avoidance/mitigation systems: Final report (Report 

No. DOT HS 812 040), Washington, DC: National 

Highway Traffic Safety Administration. 

more beneficial to focus current efforts 

on performing PAEB testing at higher 

speeds and with various lighting 

conditions using the S1 and S4 test 

scenarios. However, NHTSA’s March 

2022 RFC sought comment on an 

appropriate timeframe for including S2 

and S3 scenarios in NCAP and 

requested information from vehicle 

manufacturers on any vehicle models 

designed to address, and ideally achieve 

crash avoidance, during conduct of the 

S2 and S3 scenarios to support Agency 

evaluation as part of a future program 

upgrade. 

Summary of Comments 

Include Turning Scenarios Now 

Commenters seeking the inclusion of 

turning scenarios into PAEB evaluations 

either immediately or as soon as 

possible (Bosch, Lidar Coalition, Aptiv, 

CAS, NTSB, MEMA, Adasky, 

Advocates, The League, ZF Group, IIHS, 

ASC, Intel, CR, AARP, Velodyne, Tesla, 

and a number of individual 

commenters), noted that including 

turning scenarios would align with Euro 

NCAP’s test protocol and promote 

harmonization. NTSB did not provide a 

timeline for including turning PAEB 

scenarios in NCAP but stressed the 

importance of testing the upper limits of 

vehicle capabilities to drive innovation 

and advancement. Advocates and The 

League echoed NTSB’s opinion, with 

Advocates noting that manufacturers are 

already able to meet expectations 

internationally. The League also 

questioned why NHTSA did not 

acknowledge or adopt the Euro NCAP 

CPTA protocol. Velodyne noted Euro 

NCAP’s Roadmap for 2025, already 

highlights turning conditions as a 

priority for inclusion. 

Some commenters cited real-world 

injury data to support the prompt 

inclusion of turning scenarios, with 

Lidar Coalition reiterating nearly half of 

vehicle-to-pedestrian collisions occur at 

an intersection while the vehicle is 

turning. Although NHTSA’s data has 

previously shown intersection crashes 

involving a crossing pedestrian and 

turning vehicle are generally of lower 

severity, Lidar Coalition noted vehicles 

have grown larger since this data 

analysis, a sentiment echoed by 

Velodyne. IIHS cited its 2022 study 

which found that at intersections, the 

odds that a crash that killed a crossing 

pedestrian involved a left turn by the 

vehicle versus no turn were about twice 

as high for SUVs, nearly three times as 

high for vans and minivans and nearly 

four times as high for pickups as they 

were for passenger cars.277 The group 

suggested that NHTSA begin evaluating 

S2 scenarios as a complementary 

approach to its consumer information 

program. Lidar Coalition and another 

individual acknowledged the same 

study and noted that a similar trend 

could be seen for crashes involving 

vehicles turning right. Therefore, Lidar 

Coalition requested that NHTSA 

perform a follow-up study to investigate 

more current severity trends with 

respect to pedestrians involved in 

turning pre-crash scenarios. NACTO 

also stated vehicles are three to four 

times more likely to fatally injure 

pedestrians while turning. 

Commenters also noted the evolution 

of vehicle sensors and equipment. 

Specifically, Lidar Coalition stated that 

field-of-view limitations are of less 

concern when vehicles are equipped 

with a variety of sensors intended to 

monitor the sides of a vehicle, such as 

with BSW/BSI, and that consumers will 

expect the vehicle to be able to warn 

them of an impending crash with a 

pedestrian while turning because of 

‘‘rotational’’ sensors monitoring their 

vehicles. ZF Group noted the field-ofview of current sensors has improved 

since prior consideration of the S2 and 

S3 scenarios, and vehicles would show 

improved performance at this time. 

Adasky stated that thermal cameras are 

also adequate to address S2 and S3 

scenarios and have become more 

affordable and smaller in size. Adasky 

also discussed the capability of fusion 

sensors (thermal/RGB cameras/radar) 

and object detection software to perform 

well in these scenarios, particularly 

emphasizing the performance 

improvement that thermal cameras offer 

over RGB camera/radar fusion systems. 

ASC, Intel, Velodyne, Aptiv, and others 

also noted that improved perception 

technology is currently available. 

Lidar Coalition and Velodyne stated 

that NHTSA should balance the risk of 

an increased numbers of false positives 

(and, therefore, rear-end collisions) with 

the benefit to VRUs that may be afforded 

by including turning scenarios in PAEB 

evaluations. Both groups noted it is 

preferable for a driver to encounter a 

false positive activation and have time 

to react or override the intervention 

than to experience a false negative 

situation. Adasky recommended 

NHTSA evaluate false positive rates, as 

doing so may indicate system 

robustness and offer insight into 

possible areas of improvement. 

The Agency also received comments 

from NYC DOT/NYC DCAS, which 

expressed concern regarding consumer 

understanding of PAEB performance if 

S2 and S3 are not included in NHTSA’s 

evaluations. The group stated the 

Agency needs to clearly convey that 

PAEB systems may not be as effective 

while turning as they are when the 

vehicle is driving straight. 

In relation to timing, some 

commenters mentioned that a phased 

approach may be appropriate. Aptiv 

advocated for a timeline similar to Euro 

NCAP’s, with immediate inclusion of S2 

and S3 when the pedestrian is 

oncoming with respect to the SV before 

the turn is initiated, and later inclusion 

of S2 and S3 scenarios with the 

pedestrian receding (possibly with twoor three-years lead-time between 

oncoming and receding). Aptiv justified 

this timing by noting oncoming 

pedestrian scenarios are less challenging 

to meet than receding pedestrian 

scenarios. 

Wait To Include Turning Scenarios 

Some commenters recommended that 

NHTSA should wait to include S2 and 

S3 pre-crash scenarios in NCAP. 

Specifically, BMW, GM, Honda, Auto 

Innovators, Toyota, FCA, and HATCI 

agreed that the S1 and S4 scenarios 

should be introduced first with turning 

pre-crash scenarios added at a later 

time. Toyota did not have a specific 

recommendation regarding a timeline 

for S2 and S3 scenario inclusion but did 

note the frequency of pedestrian crashes 

in which the striking vehicle was 

turning was very low (8 percent) 

compared to scenarios S1 and S4.278

HATCI also noted the higher relative 

frequency of S1 and S4 pre-crash 

scenarios in real-world data. FCA stated 

there should be a demonstrated need 

and robust test procedure prior to the 

incorporation of any new technology 

assessment into NCAP. BMW suggested 

the latter half of this decade would be 

appropriate timing because of the 

possibility of increased false positive 

activations. Auto Innovators, FCA, and 

HATCI stated turning scenarios should 

be included in the Agency’s future 

roadmap, with Auto Innovators 

specifically noting this item should be 

targeted for the mid- to long-term range. 

GM stated the S2 and S3 scenarios 

should be phased in later as part of a 


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279A clothoid is a curve whose curvature changes 

linearly with its curve length. It is often used as a 

transition curve in highway design. 

280European New Car Assessment Programme 

(Euro NCAP) (December 2023), Vulnerable Road 

User Testing Protocol, Version 9.1. 

281 In Euro NCAP’s VRU protection protocol, head 

impactors and leg impactors are used to evaluate a 

pedestrian’s injury risk after an impact with the test 

vehicle. 

mid-term update to allow time for 

planned system and sensor 

enhancements to enter the fleet. Honda 

suggested NHTSA evaluate the current 

vehicle fleet using the Euro NCAP CPTA 

protocol to determine whether current 

systems could meet requirements. The 

automaker did not give a timeframe for 

inclusion of S2 and S3 but noted S1 and 

S4 should be given priority. 

Other Suggestions 

Commenters also provided specific 

suggestions for the S2 and S3 scenario 

test procedures in the event that NHTSA 

chose to adopt them with its final 

decision notice. Bosch recommended 

NHTSA amend the test procedure to 

have the SV perform a clothoid 

maneuver 279 instead of the constantradius maneuver currently specified. 

The group stated the clothoid path more 

closely resembles a real-world left turn 

maneuver and is more easily repeated in 

a test setting than is a constant-radius 

maneuver. ASC suggested adopting S2 

with a 10 kph (6.2 mph) SV speed and 

conducting S3 at 10 kph (6.2 mph) and 

20 kph (12.4 mph), since this would be 

in alignment with Euro NCAP’s 

protocol. 

Commenters also expressed opinions 

on how to best convey PAEB system 

performance information for S2 and S3 

pre-crash scenarios if these scenarios 

were adopted in NCAP. Rivian stated 

NHTSA should phase in levels of 

intervention by first giving credit to 

auditory warnings and then, at a later 

point in time, checking for speed 

reduction. Auto Innovators suggested 

that the Agency give credit for S2 and 

S3 performance as a ‘‘Recommended 

Technology’’ rather than integrating 

these pre-crash scenarios into an overall 

rating. Conversely, Advocates stated it 

would like to see PAEB included in the 

rating itself rather than simply listed as 

a ‘‘Recommended Technology,’’ as it 

would allow consumers to differentiate 

between vehicle safety system 

performance. 

Response to Comments and Agency 

Decisions 

While the Agency agrees with those 

commenters asserting there are inherent 

safety benefits in adopting S2 and S3 

turning scenarios to assess PAEB 

systems, it will not incorporate these 

additional test scenarios as part of this 

NCAP upgrade. 

NHTSA acknowledges the many 

reasons commenters cited for adding 

turning scenarios to PAEB evaluations 

as soon as possible, including: 

harmonization with Euro NCAP’s CPTA 

scenarios, anticipated real-world 

benefits and their potential to nullify 

the risk of a potential increase in false 

positives, the recent increase in vehicle 

size leading to more fatal crashes, recent 

sensor additions and advancements, and 

potential consumer confusion if such 

scenarios are omitted. Other 

commenters supported phasing in the 

turning PAEB test scenarios over time, 

with many agreeing with the Agency’s 

proposal to adopt S1 and S4 scenarios 

as part of this upgrade to NCAP and S2 

and S3 scenarios as part of a future 

update. These commenters, many of 

which suggested that an appropriate 

timeline for S2 and S3 adoption would 

be approximately five to seven years, 

cited limited real-world benefits 

compared to those afforded by adoption 

of the S1 and S4 scenarios, and the need 

for test procedure development and 

Agency research. Aptiv also supported a 

phased approach to adoption of the S2 

and S3 test scenarios but explained that 

certain turning scenarios could be 

added as part of the current program 

update (which also includes the 

adoption of S1 and S4) and others could 

be included two to three years later to 

allow time for PAEB systems to mature. 

Given the comments received, 

NHTSA reasons several actions must 

take place prior to the adoption of 

additional PAEB tests. Specifically, the 

Agency should first analyze recent crash 

data to further characterize scenarios for 

pedestrians involved in crashes with a 

turning vehicle. This analysis should 

allow the Agency to refine existing 

testing procedures to best address the 

safety need. Following this, NHTSA 

should conduct research testing to 

validate these test procedures and assess 

the capabilities of the current fleet. As 

part of the Agency’s research effort, it 

will consider Bosch’s suggestion to 

adopt a clothoid maneuver for the SV in 

lieu of a constant-radius maneuver to 

improve test repeatability, along with 

ASC’s recommendation to align test 

speeds to those prescribed by Euro 

NCAP. In the event the Agency develops 

a proposal to add the S2 and S3 PAEB 

tests to NCAP in the future, as many 

respondents suggested, the Agency will 

also consider the comments received 

from Rivian, Auto Innovators, and 

Advocates pertaining to performance 

requirements and incorporating the 

associated test results for the turning 

scenarios for ratings purposes. In the 

meantime, NHTSA will communicate 

on its website test specifics for the 

PAEB scenarios the Agency is adopting 

so the public may understand NCAP’s 

assessments are limited to only those 

situations reflected by the tests 

conducted and do not encompass all 

situations involving pedestrians that a 

driver may encounter, as NYC DOT/ 

NYC DCAS requested. 

12. Future Safety Areas for Pedestrian 

Protection 

NHTSA requested comments on other 

safety areas that should be considered as 

part of a pedestrian protection NCAP 

strategy for this program update or the 

future. NHTSA received many 

comments on this topic, summarized 

below. 

Summary of Comments 

Pedestrian Crashworthiness 

An overwhelming number of 

commenters responded in favor of 

incorporating a crashworthiness 

pedestrian protection component to the 

NCAP ratings. Commenters expressed 

concerns about the increasing size (both 

in height and weight) of vehicles in the 

U.S., noting that consumers often 

purchase larger vehicles to protect their 

own families while inadvertently 

placing VRUs at a disadvantage. Those 

in favor of a pedestrian crashworthiness 

component reasoned that its 

incorporation would help balance the 

risk between those inside and outside of 

the vehicle. Many commenters also 

mentioned that ADAS technologies will 

not be effective in every scenario and 

requested that NHTSA take a multipronged approach in addressing 

pedestrian injuries and fatalities. These 

individuals suggested manufacturers 

design their vehicles to be more 

pedestrian-friendly, rather than relying 

on technology that may not be 

completely effective to avoid the crash. 

Many commenters noted Euro NCAP 

currently performs this testing.280 281

The League specifically requested 

NHTSA evaluate vehicles for 

crashworthiness protection for cyclists, 

those in wheelchairs, and other VRUs 

sharing the roadway with motor 

vehicles. It stated that if this evaluation 

cannot be included in NCAP, it should 

at least be undertaken as research to 

allow all parties (consumers, 

researchers, and vehicle manufacturers) 

to better understand how vehicle design 

influences injury in these populations. 


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282https://arxiv.org/pdf/1902.11097.pdf. 

283Elizabeth E. O’Neal et al., Changes in 

Perception-Action Tuning Over Long Time Scales: 

How Children and Adults Perceive and Act on 

Dynamic Affordances When Crossing Roads, 44 

JOURNAL OF EXPERIMENTAL PSYCHOLOGY: 

HUMAN PERCEPTION AND PERFORMANCE 18 

(2018). 

284https://www.ntsb.gov/investigations/ 

accidentreports/reports/har1903.pdf. 

Direct Visibility 

Commenters also expressed concerns 

relating to direct driver visibility, with 

many stating that ADAS technologies 

involving cameras and sensors should 

not be the first solution to increase the 

field of view of a driver. Instead, they 

preferred manufacturers consider 

vehicle designs which eliminate or 

greatly reduce blind zones at early 

stages of development. Commenters 

noted that minimized blind zones may 

improve a driver’s ability to see and 

respond to VRUs who use assisted 

mobility devices, such as wheelchairs, 

walkers, or scooters, and may already be 

closer to the ground. One individual 

also suggested that visibility of a 

pedestrian or other VRU after an initial 

PAEB intervention has taken place 

should be accounted for, allowing the 

driver to physically see why the vehicle 

intervened and take appropriate actions. 

Pedestrian Mannequin Target 

Many commenters requested changes 

to the pedestrian mannequin target and/ 

or additional targets to represent a wider 

variety of VRUs more closely. Of 

particular concern was the ability of 

PAEB systems to accurately detect 

people of color. NACTO cited a 2019 

study from the Georgia Institute of 

Technology 282 that demonstrated 

automated vehicles cannot detect darker 

skin as well as lighter skin. The group 

further stated that ‘‘people of color, 

particularly Black and Indigenous 

people, are disproportionately killed 

while walking and are more likely to 

live in communities with unsafe, 

inadequate infrastructure for walking 

and biking.’’ NSC added that although 

pedestrian deaths represent about 14% 

of all traffic deaths among white, nonHispanics, they represent more than 

20% of pedestrian fatalities among 

Hispanics, Black non-Hispanics, and 

Native Americans. NSC further noted 

that, compared to white non-Hispanics, 

the pedestrian fatality rate for Native 

Americans is almost four times as high, 

and the pedestrian fatality rate for the 

Black community is nearly twice as 

high. These sentiments were detailed by 

safety advocates, local government 

organizations, and individuals alike. 

Commenters also expressed concerns 

with the height of the pedestrian 

mannequin target, particularly for 

shorter individuals, including children. 

An individual commenter stated that 

children are vulnerable to pedestrian 

impacts not only because of their size 

relative to a modern vehicle’s size, but 

also because of the behavioral 

differences between adults and 

children. Specifically, the commenter 

noted that children are less likely to use 

the same judgment around vehicles as 

adults, citing evidence to support this 

claim.283 NSC stated that, in 2017, one 

in every five children killed in a crash 

were pedestrians. Several individuals 

and one group (Bikemore) stated the 

pedestrian mannequin should be 

representative of a 2-year-old child. 

MEMA noted there are currently 2-yearold and 7-year-old pedestrian 

mannequins available, adding they 

should also be included in a future 

NCAP upgrade. Auto Innovators 

supported the use of a 7-year-old child 

target in the future. Uhnder stated child 

targets should be used in all testing, 

noting that all VRUs should be equally 

represented. ASC also stated all VRUs 

should be represented equally, adding 

that NHTSA should consider using 

them beyond scenario S1d. 

Commenters also noted several other 

areas of potential interest for 

characteristics of the pedestrian target, 

including: gender, clothing type and 

color, carried or pushed objects (such as 

a stroller), and the use of assistive 

mobility devices like wheelchairs and 

scooters. For example, AARP suggested 

that PAEB systems should be able to 

recognize pedestrians carrying shopping 

bags or walking a bicycle across a road. 

Advocates cited the NTSB’s findings 

that a 2018 crash involving a vehicle 

equipped with ADAS technologies 

occurred because the vehicle did not 

properly identify the pedestrian walking 

her bicycle across the road.284 One 

commenter who uses a wheelchair 

stated those using assistive mobility 

devices like wheelchairs are already 

more difficult to see while traveling 

because their head is lower to the 

ground, including sometimes below the 

hoods of vehicles. Likewise, one 

individual commenter noted wheelchair 

users are 36 percent more likely to be 

killed as pedestrians than the overall 

population. Uhnder and another 

individual stated that darker clothing is 

more difficult for the human eye to 

distinguish from surroundings in the 

dark, particularly for pedestrians 

traveling at night. It would be 

imperative for a PAEB system to 

recognize and respond to a pedestrian 

wearing such clothing. 

Finally, Auto Innovators and GM 

stressed the need for field pedestrian 

crash data to support any additional 

safety areas addressed by NCAP. 

Inclement/Challenging Weather 

Many comments addressed PAEB 

performance in poor weather conditions 

and in a variety of environments. As 

discussed in previous sections of this 

notice, many respondents expressed 

concerns over performance degradation 

in rain, snow, and fog. Walk and Roll 

Bellingham stated that a system that 

will not work in these conditions would 

not be useful to them, as inclement 

weather is common. 

One individual commented that many 

crashes occur during dawn and dusk, 

which are mid-level lighting conditions. 

The commenter stated this may be due 

to sun glare or to more individuals 

traveling at these times of day, noting it 

should be a targeted scenario due to 

frequency of occurrence. 

Other Scenarios To Consider 

Commenters also suggested other 

PAEB scenarios and variations the 

Agency should consider, with Uhnder, 

ASC, and one individual recommending 

the addition of a test simulating a 

pedestrian crossing the road with 

another vehicle approaching in 

oncoming traffic, both in daylight and 

dark lighting conditions. Uhnder also 

suggested including a test with a 

pedestrian crossing under a bridge or 

walkway. Uhnder stated that these 

scenarios, which had once been difficult 

for the SV to pass because sensors could 

not properly resolve the pedestrian, are 

now less challenging for modern 

sensors. Vayyar recommended 

including a parking lot scenario in 

which a vehicle enters and exits a 

parking space. CAS noted that highway 

signage, crosswalk painting, and 

construction should be accounted for in 

NHTSA’s testing. 

One individual pointed out there is 

currently no provision to mitigate a 

crash with a pedestrian that may be 

lying in the road, and that such a case 

might apply to a pedestrian that has 

already been struck. 

TRC, AARP, and one individual 

pointed out this proposal does not 

address backovers. TRC and the 

individual commenter noted Euro 

NCAP has developed and approved a 

protocol for reverse pedestrian braking. 

Accordingly, TRC asserted the Agency 

could readily adopt this test as part of 

its PAEB test procedures. Similarly, the 

individual commenter expressed that it 

was unacceptable NHTSA did not plan 


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285https://www.reginfo.gov, RIN 2127–AK98. 

286 88 FR 34366 (May 26, 2023). 

287National Center for Statistics and Analysis. 

(2023, June), Pedestrians. (Traffic Safety Facts, 2021 

Data. Report No. DOT HS 813 458), Washington, 

DC: National Highway Traffic Safety 

Administration. 

288Swanson, E., Foderaro, F., Yanagisawa, M., 

Najm, W.G., & Azeredo, P. (2019, August), Statistics 

of light-vehicle pre-crash scenarios based on 2011– 

2015 national crash data (Report No. DOT HS 812 

745), Washington, DC: National Highway Traffic 

Safety Administration. 

289European New Car Assessment Programme 

(Euro NCAP) (December 2023), Test Protocol—AEB/ 

LSS VRU systems, Version 4.5. 

to include reverse and turning scenarios 

until the 2025–2031 timeframe. AARP 

suggested that including a reverse 

pedestrian test will improve PAEB 

technology more rapidly. 

Finally, Vision Zero Network and 

NACTO expressed concerns with a 

PAEB system’s ability to distinguish 

pedestrians traveling in a crowd. 

Vehicle to Everything (V2X) 

Several commenters expressed that 

V2X technology could help drivers and 

VRUs avoid potential hazards, 

especially as vehicles increasingly share 

roads with pedestrians, bicyclists, etc. 

5G Automotive Association noted that 

V2X technology developed under the 

3rd Generation Partnership Project 

already supports vehicle-to-pedestrian 

communications. Two additional 

commenters stated V2X technology 

could be used specifically to help 

address the nighttime pedestrian crash 

problem. ASC and one individual 

commenter stated that vehicles could 

assess nearby smartphone location data 

to locate and track VRUs. ASC suggested 

NHTSA perform testing with location 

data enabled smartphones attached to 

the pedestrian mannequin for vehicles 

equipped with this technology. 

Other Comments 

ZF Group commented that pedal 

misapplication is a concern and that as 

the country ages, incidents could 

increase. Additionally, the group noted 

JNCAP has developed a protocol to 

evaluate acceleration suppression 

technologies to mitigate the risk and 

suggested NHTSA investigate this 

further. 

Another individual stated NHTSA 

should require vehicles to make sound 

at low speeds to warn pedestrians that 

a vehicle is in motion nearby. 

Response to Comments and Agency 

Decisions 

Many commenters stated the Agency 

should pursue multiple paths beyond 

those specifically proposed in the 

March 2022 notice to fully mitigate 

pedestrian crashes. NHTSA’s response 

to these comments follows. 

Pedestrian Crashworthiness 

Many commenters expressed that 

vehicle manufacturers should take 

pedestrian crashworthiness into account 

when designing vehicles. As noted 

previously, NHTSA intends to develop 

a pedestrian crashworthiness FMVSS to 

address pedestrian head impacts to 

vehicle hoods and has also proposed a 

separate testing program for 

NCAP.285 286 Comments will be 

considered independently in the context 

of those actions. The Agency hopes that, 

if implemented, these efforts may help 

to address the need to balance risk to 

occupants in the vehicle with those 

outside of the vehicle. 

Direct Visibility 

The Agency is looking into this 

further to determine the best approach 

to address these issues and has included 

driver visibility in the 10-year roadmap 

for consideration in future NCAP 

updates. 

Pedestrian Mannequin Target 

NHTSA notes the proposed 4activePA 

adult and child articulated mannequins 

represent a 50th percentile male adult 

and a 7-year-old child. Both pedestrian 

mannequin targets have the same 

clothing and skin/hair color. Many 

commenters suggested alternative 

pedestrian targets, noting that a variety 

of VRUs should be accounted for. This 

included people of color; VRUs of 

differing heights, ages, and clothing 

styles; those who use assistive mobility 

devices; or those carrying objects which 

may impede proper detection. 

Because the Agency is not currently 

aware of alternative pedestrian targets 

proven to be reliable, including those 

representing a toddler-aged child, those 

using mobility aids, or those with 

alternative clothing, the proposed 

4active targets will be adopted for this 

NCAP update. As noted previously, 

these are the pedestrian targets adopted 

for use by Euro NCAP. However, 

NHTSA is currently conducting 

research to evaluate vehicle response to 

various pedestrian characteristics, such 

as clothing color and type. This research 

will inform next steps for the Agency. 

Regarding children in particular, the 

Agency notes that, while there are likely 

behavioral differences between adults 

and children, as one commenter 

claimed, crash data show that child 

pedestrian involvement is relatively 

low. In 2021, less than one-sixth (15 

percent) of children aged 14 and 

younger killed in traffic crashes were 

pedestrians, and the age group with the 

fewest pedestrian fatalities was ages five 

to nine years, followed by the less than 

five-year-old age group.287 That said, for 

this NCAP update, the Agency will 

utilize the seven-year-old 4activePA 

mannequin for S1d. Use of this 

pedestrian target in at least one 

condition should ensure that vehicle 

manufacturers account for smaller 

pedestrians in their PAEB system 

designs while still targeting the largest 

population of pedestrians for the 

majority of adopted conditions. The 

Agency may revisit this decision in the 

future if additional mannequins are 

found to be reliable during testing, 

sensing technology improves, and/or the 

real-world crash problem changes. 

Inclement/Challenging Weather 

Conditions 

NHTSA has decided that all NCAP 

PAEB testing will occur in dry, clear 

conditions free of fog, smoke, ash, or 

other airborne particulate matter with 

the minimum visibility range stated. 

Doing so should ensure that each 

vehicle is evaluated under the same 

circumstances and maintain a 

reasonable test burden. 

NHTSA acknowledges that pedestrian 

crashes occur in various weather 

conditions. According to Volpe data 

from 2011–2015, approximately 10 

percent of fatal pedestrian crashes and 

13 percent of injurious pedestrian 

crashes occurred during adverse 

weather annually.288 PAEB systems 

should be functional in a variety of 

weather conditions. This especially 

holds true for areas of the country 

subject to frequent inclement weather. 

However, for an NCAP testing 

program to be useful to consumers, 

repeatability and reproducibility of test 

results is imperative. The presence of 

precipitation could influence the 

outcome of the tests, as pavement 

covered in precipitation may have a 

lower coefficient of friction than dry 

pavement and falling precipitation may 

interfere with sensing systems such that 

vehicles are not independently 

subjected to the same conditions. The 

same logic applies to visibility at the 

test site. A current industry standard 

specifies the horizontal visibility at 

ground level must be greater than 1 km 

(0.62 miles), a standard also adopted by 

Euro NCAP for its AEB/LSS protocol.289

Thus, NHTSA will conduct all NCAP 

PAEB tests in dry, clear conditions free 

of fog, smoke, ash, or other airborne 

particulate matter with the minimum 

visibility range stated. However, similar 

to that which the Agency indicated for 


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Federal Register / Vol. 89, No. 232 / Tuesday, December 3, 2024 / Notices 96017 

290National Center for Statistics and Analysis 

(2019, June), Bicyclists and other cyclists: 2017 data 

(Traffic Safety Facts. Report No. DOT HS 812 765), 

Washington, DC: National Highway Traffic Safety 

Administration. 

291European New Car Assessment Programme 

(Euro NCAP) (December 2023), Test Protocol—AEB/ 

LSS VRU systems, Version 4.5. 

292https://injuryfacts.nsc.org/home-andcommunity/safety-topics/bicycle-deaths/. 

turning scenarios S2 and S3, NHTSA 

may communicate on its website 

possible system limitations pertaining to 

environmental conditions not assessed 

by NCAP to lessen consumer confusion 

relating to expectations for system 

functionality. Further, notwithstanding 

the adopted test specificity, NHTSA 

encourages manufacturers to continue 

working toward delivering PAEB 

systems that are robust and that 

function in as many real-world 

environments as possible. 

Other Scenarios To Consider 

NHTSA acknowledges that real-world 

driving involves a variety of situations. 

Commenters noted that the proposed 

testing conditions do not address such 

scenarios as: parking lots; cases where 

an oncoming vehicle is also present; 

situations where a pedestrian is crossing 

under a structure such as a bridge; 

backover incidents; or other 

surroundings such as signs, roadway 

markings, and other visual clutter, such 

as that found in construction zones. 

The Agency agrees that each of these 

situations represents a possible realworld case in which PAEB is expected 

to function. However, it would not be 

possible to test every permutation, as 

the resources required for this endeavor 

would make such a testing program 

prohibitive. As mentioned in previous 

sections, NHTSA plans to monitor realworld cases and has the authority to 

investigate situations which prove 

increasingly problematic. 

Several commenters expressed 

concern that a specific mitigation plan 

for backover pedestrian crashes was not 

included in the Agency’s March 2022 

proposal, beyond inclusion in a shortterm roadmap. At that time, NHTSA 

referred to data which showed NHTSA 

backing data from 2021 in-traffic 

pedestrian crashes shows that most 

pedestrian fatalities where the first 

harmful event was a collision with the 

vehicle are a result of initial contact 

with the front of the vehicle. As detailed 

in the March 2022 RFC notice, more 

time is required for NHTSA to review 

real-world data and the effects of 

FMVSS No. 111, ‘‘Rear visibility.’’ This 

information will also help inform 

changes to the rear automatic braking 

(RAB) test procedure, which remains 

under further development. Thus, 

NHTSA concludes that while Euro 

NCAP has developed an RAB protocol 

for use in its testing, it would be 

premature for the Agency to incorporate 

RAB as a U.S. NCAP ADAS technology 

at this time. 

NHTSA will also not perform PAEB 

testing for a lying, stationary pedestrian 

at this time. These cases are likely rare 

and would not represent a large portion 

of the pedestrian crash problem. 

Further, there is not a test procedure 

developed at this time to address such 

a scenario. Similarly, there is not a test 

procedure currently developed to assess 

a PAEB system’s response to multiple 

pedestrians in a group, so this scenario 

will also not be incorporated into NCAP 

testing at this time. 

Vehicle to Everything (V2X) 

NHTSA also received a suggestion to 

incorporate V2X support into its PAEB 

test procedures for dark lighting 

conditions. This would allow vehicles 

to utilize smartphone location data to 

locate the pedestrian target and map its 

movement. As a result, V2X technology 

could help to mitigate cases in which a 

VRU is not visible due to obstruction, 

lack of lighting, or other environmental 

factors. However, because the Agency 

has not conducted testing of a 

smartphone-enabled test target, it would 

be premature to incorporate this 

additional specification into PAEB 

testing at this time. Further, DOT 

research has not yet determined 

whether cellular-based V2X would be 

able to support safety-critical crash 

avoidance technologies, although it may 

have benefits for weather, traffic, and 

infrastructure-related alerts. NHTSA 

may consider the inclusion of this 

technology in NCAP in the future. 

Other Comments Related to Pedestrian 

Safety 

As part of NHTSA’s AEB research to 

further assess the rear-end safety 

problem, characterize current vehicles, 

and identify potential countermeasures, 

the Agency will study pedal 

misapplication. AEB/PAEB test 

procedure modifications it deems 

necessary as a result of that effort may 

be adopted as part of subsequent 

updates to NCAP. 

NHTSA notes all electric and hybrid 

vehicles manufactured on or after March 

1, 2021, are required to produce a sound 

at low speeds per FMVSS No. 141, 

‘‘Minimum sound requirements for 

hybrid and electric vehicles.’’ This 

standard should address concerns 

related to quiet vehicles and pedestrian 

crash risk. 

13. Acceptable Timeframe To Add 

Bicyclist Testing and Test Procedures 

Other Than Euro NCAP’s To Address 

Bicyclist Crashes 

In its March 2022 RFC notice, the 

Agency committed to conducting 

additional research to address injuries 

and fatalities for other VRUs, 

specifically bicyclists and motorcyclists. 

NHTSA’s current PAEB test procedure 

does not include a specific bicyclist 

component, although PAEB systems 

capable of detecting bicyclists may 

exist. The rising number of bicyclists 

killed on U.S. roads 290 prompted the 

Agency to study and determine the 

viability of Euro NCAP’s AEB bicyclist 

tests.291

Acknowledging the current state of 

bicyclist PAEB testing in the U.S., 

NHTSA requested comments detailing 

when it would be acceptable to add 

bicyclist PAEB testing to its suite of 

ADAS tests, and whether there are other 

test procedures available beyond Euro 

NCAP’s to evaluate. The Agency also 

requested information from vehicle 

manufacturers on any currently 

available models with the capability to 

validate the bicyclist target and test 

procedures used by Euro NCAP to 

support evaluation for a future NCAP 

program upgrade. 

Summary of Comments 

An overwhelming majority of 

commenters who addressed the issue 

urged NHTSA to move forward with a 

bicyclist component as soon as possible. 

Somerville Bicycle Safety noted that 

according to NSC, bicyclist fatalities 

increased 44 percent from 2011 to 

2020.292 The League stated that other 

NHTSA FARS data shows that in 2020, 

276 bicyclists were killed by the 

grouped crash type, ‘‘motorist 

overtaking bicyclist,’’ which was more 

than three times the number of those 

killed in the next crash type, ‘‘parallel 

paths—other circumstances,’’ and noted 

that these crash types could be 

addressed by AEB. 

Vision Zero Network, the League, and 

Bike Cleveland noted that rising cyclist 

deaths are cited as a targeted issue in 

USDOT’s National Roadway Safety 

Strategy (NRSS). Further, the BIL’s 

requirement to consider benefits of 

harmonization with domestic and 

international ratings systems was cited 

by PeopleForBikes and Ride New 

Orleans. Advocates also noted there is 

an increased interest from the U.S. DOT 

and other transportation organizations 

in the use of bicycles in urban 

transportation programs to travel to 

school and work. 

Respondents also cited the 

availability of a bicyclist target and Euro 


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96018 Federal Register / Vol. 89, No. 232 / Tuesday, December 3, 2024 / Notices 

293NTSB Safety Recommendation H–19–36. 

294 Including ISO19206–2, ISO19206–4, and 

ISO19206–5 (under development) targets. 

295Albrecht, H. (2015, November 5). ‘‘Pedestrian 

Test Mannequins Objective Criteria for Evaluating 

Repeatability and Accuracy of PCAM Systems.’’ 

SAE Active Safety Symposium. Plymouth, MI. 

296National Highway Traffic Safety 

Administration. Fatality and Injury Reporting 

System Tool (FIRST), Version 6. Fatality Analysis 

Reporting System (FARS): 2016–2020 Final File. 

NCAP’s protocol in support of NHTSA’s 

adoption of a bicyclist component for 

PAEB. Intel, Vision Zero Network, Safe 

Roads Alliance, Aptiv, Somerville 

Bicycle Safety, PeopleForBikes, AARP, 

The League, NACTO, Ride New Orleans, 

Advocates, CAS, ITS America, Bike 

Cleveland, KAC, ASC, FSS, and Vayyar 

all referred to Euro NCAP’s readily 

available protocol as a reason to move 

urgently. Intel specifically noted that 

bicyclist AEB should be included in the 

2023–2024 timeframe of NCAP’s 

roadmap because of this readily 

available and updated protocol. Lidar 

Coalition noted that NHTSA’s plan to 

not include bicyclist AEB until a future 

NCAP upgrade appears out of step with 

the Agency’s stated goals to address 

areas of substantial safety need and to 

harmonize with Euro NCAP wherever 

possible. The League noted 

inconsistencies in NHTSA’s 

justifications for including other ADAS 

technologies for this NCAP upgrade, 

including BSI and CIB, to encourage 

proliferation and development of 

capabilities in the vehicle fleet, while 

not also including bicyclist AEB. Other 

commenters stated that NHTSA, and 

therefore the U.S., will lag behind 

European countries by a decade should 

NHTSA decide to delay inclusion of 

bicyclist detection as shown in the draft 

NCAP roadmap. Several commenters 

stated that Australasian NCAP, JNCAP, 

and IIHS, in addition to Euro NCAP, 

already take bicyclists into account in 

their PAEB/AEB testing. 

The NTSB submitted a comment 

referring to its 2019 recommendation 

that NHTSA incorporate vehicle-tobicyclist crash avoidance capabilities in 

NCAP as a mechanism to incentivize 

incorporation of the technology in 

vehicles.293 The accompanying study 

showed that vehicle ADAS could reduce 

the frequency of bicyclist crashes. 

Some commenters stated that the 

Agency should wait until a future NCAP 

upgrade to include bicyclist detection in 

PAEB/AEB testing. These included Auto 

Innovators, HMNA, GM, Honda, and 

HATCI. GM and Auto Innovators stated 

the Agency should take more time for 

NCAP to evolve and should adopt Euro 

NCAP procedures when NHTSA 

eventually adopts bicyclist detection 

protocols. Honda acknowledged that 

bicyclist detection is an important 

feature that should be included but 

suggested that it be included at a future 

time, as Scenarios S1 and S4 should be 

prioritized. HATCI suggested that if 

NHTSA plans to harmonize with Euro 

NCAP, NHTSA could move forward as 

part of a future upgrade, but if the 

Agency is going to make changes to the 

protocol, then HATCI recommended 

that NHTSA publish the amended test 

procedure for review and comment. 

Finally, DRI mentioned that, in its 

experience, the current bicyclist targets 

available on the market lack the 

durability for continuous testing during 

which impacts may occur. 

Several commenters stated more 

research would be useful to inform 

decisions regarding appropriate test 

scenarios and conditions. Auto 

Innovators, GM, Tesla, FCA, and the 

League suggested that NHTSA review 

U.S. crash data to determine any 

necessary adaptations to Euro NCAP test 

scenarios for the U.S. market. The 

groups suggested the Agency should 

take into consideration variables such as 

specific crash scenarios commonly seen 

in fatal crashes, SV and bicyclist speeds, 

and road features and markings specific 

to the U.S. market. The League also 

stated that door opening crashes, in 

which a vehicle occupant opens their 

door into the path of an approaching 

bicyclist, are likely underrepresented in 

FARS data, as other sources estimate 

that 7 percent to 20 percent of all cyclist 

crashes involve this crash type. Uhnder 

also supported continued studies to 

determine which scenarios are most 

likely to be found on U.S. roadways. 

Uhnder and ASC also suggested that 

NHTSA undertake a characterization 

study of bicyclist targets 294 to include 

radar cross section (RCS), like the study 

completed for pedestrian targets, prior 

to incorporation of a bicyclist 

component.295

The League stated when bicyclist AEB 

testing begins, it should be conducted in 

both daylight and dark lighting 

conditions. The group stated it is 

relevant to include these test conditions 

because NHTSA FARS data showed 

between 2016 and 2020, about 50 

percent of bicyclist fatalities occurred 

during dark lighting conditions.296

In addition to bicycles, commenters 

stated other signatures, such as scooters 

and wheelchairs, should also be 

detected by vehicle AEB systems. MIC/ 

MSF specifically recommended NHTSA 

also ensure the inclusion of motorcyclist 

tests. One individual stressed the 

importance of bicycle infrastructure, 

requesting safer spaces for cyclists to 

travel on the roadway. 

Response to Comments and Agency 

Decisions 

NHTSA recognizes many of the 

commenters supported the inclusion of 

bicyclist testing in NCAP and wanted 

the Agency to take such action 

immediately. Two of the main reasons 

cited for this inclusion were the need to 

fulfill initiatives established in the 

NRSS and BIL mandates, as well as 

incentivizing the proliferation and 

development of system capabilities in 

the vehicle fleet. These commenters 

referenced several existing test 

procedures and test targets that could be 

utilized to assess system performance to 

mitigate light vehicle crashes with 

bicyclists. 

However, the Agency agrees with 

those commenters who suggested it 

should conduct additional research 

prior to adoption of a bicyclist 

component into NCAP. Existing test 

procedures, such as that in Euro NCAP, 

for evaluating crash avoidance 

technologies for bicyclist and 

motorcyclist protection need further 

evaluation for their effectiveness, 

objectivity, and suitability for vehicles 

sold in the U.S. Additional assessment 

is also needed on the durability and 

suitability of the targets used in the 

tests. 

NHTSA has expedited its research on 

AEB for other VRUs, namely bicyclists 

and motorcyclists. Initial research has 

been performed on surrogate bicycle 

and motorcycle targets for testing and 

global test procedures to evaluate their 

effectiveness and suitability for use in 

performance tests. Further crash data 

analysis will be performed to better 

characterize the critical safety scenarios 

that account for bicycle and motorcycle 

injuries and fatalities. Collectively, this 

information will lead to test procedures 

that can be used to assess safety 

performance of vehicles sold in the U.S. 

This research effort is expected to be 

completed in 2025. As noted in the midterm updates to NCAP in the NCAP 

roadmap finalized in this notice, 

NHTSA has included evaluation of AEB 

for mitigating crashes with bicyclists 

and motorcyclists starting with model 

year 2028 vehicles. 

E. Summary of Adopted Tests for 

Pedestrian Automatic Emergency 

Braking 

Tabular summaries of the adopted test 

conditions and variants for PAEB are 

provided in Tables 19 and 20. 


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Federal Register / Vol. 89, No. 232 / Tuesday, December 3, 2024 / Notices 96019 

TABLE 19—ADOPTED NCAP PAEB DAYLIGHT TEST CONDITIONS AND VARIANTS

Test condition Size Movement 

classification Path origin Overlap (%) Obstruction Test No. 

Test speeds 

(kph (mph)) 

SV Pedestrian 

S4c ................... Adult (Facing 

Away).

Walk ..................... Right .................... 25 No .................... 1 

2 

3 

4 

5 

6 

10 (6.2) 

20 (12.4) 

30 (18.6) 

40 (24.9) 

50 (31.1) 

60 (37.3) 

5 (3.1). 

5 (3.1). 

5 (3.1). 

5 (3.1). 

5 (3.1). 

5 (3.1). 

S4a ................... Adult (Facing 

Away).

Stationary ............. Right .................... 25 No .................... 7 

8 

9 

10 

11 

12 

10 (6.2) 

20 (12.4) 

30 (18.6) 

40 (24.9) 

50 (31.1) 

60 (37.3) 

0. 

0. 

0. 

0. 

0. 

0. 

S1b ................... Adult ..................... Walk ..................... Right .................... 50 No .................... 13 

14 

15 

16 

17 

18 

10 (6.2) 

20 (12.4) 

30 (18.6) 

40 (24.9) 

50 (31.1) 

60 (37.3) 

5 (3.1). 

5 (3.1). 

5 (3.1). 

5 (3.1). 

5 (3.1). 

5 (3.1). 

S1a ................... Adult ..................... Walk ..................... Right .................... 25 No .................... 19 

20 

21 

22 

23 

24 

10 (6.2) 

20 (12.4) 

30 (18.6) 

40 (24.9) 

50 (31.1) 

60 (37.3) 

5 (3.1). 

5 (3.1). 

5 (3.1). 

5 (3.1). 

5 (3.1). 

5 (3.1). 

S1e ................... Adult ..................... Run ...................... Left ....................... 50 No .................... 25

26 

27 

28 

29 

30 

10 (6.2) 

20 (12.4) 

30 (18.6) 

40 (24.9) 

50 (31.1) 

60 (37.3) 

8 (5.0). 

8 (5.0). 

8 (5.0). 

8 (5.0). 

8 (5.0). 

8 (5.0). 

S1d ................... Child ..................... Run ...................... Right .................... 50 Yes .................. 31 

32 

33 

34 

35 

36 

10 (6.2) 

20 (12.4) 

30 (18.6) 

40 (24.9) 

50 (31.1) 

60 (37.3) 

5 (3.1). 

5 (3.1). 

5 (3.1). 

5 (3.1). 

5 (3.1). 

5 (3.1). 

TABLE 20—ADOPTED NCAP PAEB DARKNESS TEST CONDITIONS AND VARIANTS

Test condition Size Movement 

classification Path origin Overlap (%) Obstruction Test No. 

Test speeds 

(kph (mph)) 

SV Pedestrian 

S4c ................... Adult (Facing 

Away).

Walk ..................... Right .................... 25 No .................... 1 

2 

3 

4 

5 

6 

10 (6.2) 

20 (12.4) 

30 (18.6) 

40 (24.9) 

50 (31.1) 

60 (37.3) 

5 (3.1). 

5 (3.1). 

5 (3.1). 

5 (3.1). 

5 (3.1). 

5 (3.1). 

S4a ................... Adult (Facing 

Away).

Stationary ............. Right .................... 25 No .................... 7 

8 

9 

10 

11 

12 

10 (6.2) 

20 (12.4) 

30 (18.6) 

40 (24.9) 

50 (31.1) 

60 (37.3) 

0. 

0. 

0. 

0. 

0. 

0. 

S1b ................... Adult ..................... Walk ..................... Right .................... 50 No .................... 13 

14 

15 

16 

17 

18 

10 (6.2) 

20 (12.4) 

30 (18.6) 

40 (24.9) 

50 (31.1) 

60 (37.3) 

5 (3.1). 

5 (3.1). 

5 (3.1). 

5 (3.1). 

5 (3.1). 

5 (3.1). 

S1a ................... Adult ..................... Walk ..................... Right .................... 25 No .................... 19 

20 

21 

22 

23 

24 

10 (6.2) 

20 (12.4) 

30 (18.6) 

40 (24.9) 

50 (31.1) 

60 (37.3) 

5 (3.1). 

5 (3.1). 

5 (3.1). 

5 (3.1). 

5 (3.1). 

5 (3.1). 

S1e ................... Adult ..................... Run ...................... Left ....................... 50 No .................... 25

26 

27 

28 

29 

30 

10 (6.2) 

20 (12.4) 

30 (18.6) 

40 (24.9) 

50 (31.1) 

60 (37.3) 

8 (5.0). 

8 (5.0). 

8 (5.0). 

8 (5.0). 

8 (5.0). 

8 (5.0). 


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96020 Federal Register / Vol. 89, No. 232 / Tuesday, December 3, 2024 / Notices 

297Wang, J.S. (2019, March), Target crash 

population for crash avoidance technologies in 

passenger vehicles (Report No. DOT HS 812 653). 

Washington, DC: National Highway Traffic Safety 

Administration. 

298Monticello, M. (2017, June 29), The positive 

impact of advanced safety systems for cars: The 

latest car-safety technologies have the potential to 

significantly reduce crashes, Consumer Reports, 

https://www.consumerreports.org/car-safety/ 

positive-impact-of-advanced-safety-systems-forcars/. 

299Leslie, A.J., Kiefer, R.J., Meitzner, M.R., & 

Flannagan, C.A. (2019), Analysis of the field 

effectiveness of General Motors production active 

safety and advanced headlighting systems, The 

University of Michigan Transportation Research 

Institute and General Motors LLC, UMTRI–2019–6. 300UMTRI found systems having longer vehicle 

detection ranges provided an estimated 26 percent 

reduction in lane change crashes, compared to a 

corresponding non-significant 3 percent reduction 

for those systems having shorter detection ranges. 

301 Docket No. NHTSA–2019–0102–0010. 

302A vehicle’s blind zone is defined by two 2.5 

m- (8.2 ft.-) wide rectangular regions that extend to 

the side and rear of the SV and begin at the rearmost 

part of the SV’s side mirror housing, in the 

housing’s fully extended operating position, and 

runs perpendicular to the SV’s longitudinal 

centerline. The length of the blind zone is 

dependent upon the speed differential between the 

SV and the POV. See Blind Spot Detection System 

Confirmation Test for a complete definition. 

303The POV selected must be 445 to 500 cm (175 

to 197 in.) in length and 178 to 193 cm (70 to 76 

in.) wide, measured at the widest part of the vehicle 

exclusive of signal lamps, marker lamps, outside 

rearview mirrors, flexible fender extensions, and 

mud flaps. Width is determined with doors and 

windows closed and the wheels in the straightahead position. The color of the vehicle is 

unrestricted. 

TABLE 20—ADOPTED NCAP PAEB DARKNESS TEST CONDITIONS AND VARIANTS—Continued 

Test condition Size Movement 

classification Path origin Overlap (%) Obstruction Test No. 

Test speeds 

(kph (mph)) 

SV Pedestrian 

S1d ................... Child ..................... Run ...................... Right .................... 50 Yes .................. 31 

32 

33 

34 

10 (6.2) 

20 (12.4) 

30 (18.6) 

40 (24.9) 

5 (3.1). 

5 (3.1). 

5 (3.1). 

5 (3.1). 

*All darkness testing is to occur without the use of overhead artificial lighting. 

VI. Adding Blind Spot Technologies 

NHTSA is adding assessments for two 

blind spot technologies, blind spot 

warning (BSW) and blind spot 

intervention (BSI), to NCAP’s crash 

avoidance program. As discussed in 

NHTSA’s March 2022 RFC notice, these 

technologies have the potential to 

prevent or mitigate five pre-crash lane 

change or merge scenarios, representing 

approximately 503,070 crashes 

annually, on average—8.7 percent of all 

crashes that occur on U.S. roadways. 

These crashes result in 542 fatalities on 

average, and 188,304 MAIS 1–5 injuries 

annually, representing 1.6 percent of all 

fatalities and 6.7 percent of all injuries, 

respectively.297 While the target 

population for blind spot technologies 

may not be as large as the populations 

for AEB technologies, their high 

consumer acceptance rate and potential 

safety improvements, both discussed 

later in this section, support their 

inclusion in the Agency’s signature 

consumer information program. 

A. Blind Spot Technologies 

1. Blind Spot Warning (BSW) 

A BSW system is a warning-based 

driver assistance system that 

automatically alerts a driver that 

another vehicle is approaching, or being 

operated within, the blind spot of the 

driver’s vehicle in an adjacent lane. 

Depending on the system design, 

additional BSW features may be 

activated if the system presents an alert 

and the driver operates their turn signal 

indicator. In either case, the BSW 

system provides information intended 

to assist a driver contemplating or 

initiating a lane change. 

Current BSW systems use camera-, 

radar-, or ultrasonic-based sensors, or 

some combination thereof, to detect 

other vehicles. These sensors are 

typically located on the sides and/or 

rear of a vehicle. BSWs may be auditory, 

visual (most common), or haptic. Visual 

alerts are usually presented in the 

outboard side mirror glass, inside edge 

of the mirror housing, or at the base of 

the front A-pillars inside the vehicle. 

When the BSW system detects that 

another vehicle traveling in an adjacent 

lane has entered or is approaching the 

driver’s blind spot, the BSW visual alert 

is typically continuously illuminated. 

However, if the driver engages the turn 

signal in the direction of the adjacent 

vehicle while the visual alert is present, 

the visual alert may transition to a 

flashing state and/or be supplemented 

with an additional auditory or haptic 

alert (e.g., beeping or vibration of the 

steering wheel or seat, respectively). 

Adding BSW systems to NCAP’s 

ADAS evaluations is appropriate not 

only because the technology addresses a 

safety need but also because of 

consumer interest and known 

differences in detection capabilities and 

operating conditions, the latter of which 

can impact system effectiveness. The 

general appeal of BSW systems is 

reflected by the systems’ penetration 

rates. In the six years between model 

years 2018 and 2024, the percentage of 

the fleet fitted with standard BSW 

systems rose from 5.8 to 57 percent. 

Further, in market research conducted 

by Consumer Reports, the organization 

found an overwhelming majority of 

vehicle owners were satisfied with BSW 

technology, and 60 percent of those 

surveyed believed BSW technology had 

helped them avoid a crash.298

Additionally, in a study evaluating the 

real-world effectiveness of ADAS 

technologies in model year 2013 to 2017 

GM vehicles, UMTRI found BSW system 

effectiveness increased substantially 

(i.e., translating to a larger reduction in 

lane-change crashes) for systems 

offering longer vehicle detection 

ranges.299 300 Whereas one vehicle’s 

BSW system may simply augment a 

driver’s visual awareness, another may 

more effectively prevent crashes by 

warning of potential higher speed 

differential lane change conflicts. As 

such, there are reasons to provide 

consumers with BSW system 

performance information, regardless of 

the technology’s high equipment rates 

and consumers’ positive appreciation 

for such systems. 

Proposed BSW Test Procedure 

The Agency proposed to utilize its 

draft blind spot detection (BSD) test 

procedure 301 (referred to in this notice 

as BSW) to assess systems’ performance 

and capabilities in blind spot related 

pre-crash scenarios. This test procedure 

evaluates a vehicle’s BSW system using 

two tests performed on the test track: 

the Straight Lane Converge and Diverge 

Test and the Straight Lane Pass-by Test. 

These tests assess whether a test 

vehicle’s (SV’s) BSW system presents a 

warning when other vehicles (POVs) are 

within or approaching the driver’s blind 

spot, or blind zone.302 In each test, the 

POV represents a high-production midsized passenger car.303 In the proposed 

procedure, neither the SV nor POV turn 

signals may be activated at any point 

during any test trial. A short description 

of each proposed test scenario and the 


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Federal Register / Vol. 89, No. 232 / Tuesday, December 3, 2024 / Notices 96021 

related requirement for a passing result 

is provided below. 

• Straight Lane Converge and Diverge 

Test—The POV and SV are driven 

parallel to one another in the outbound 

lanes of a three-lane straight road. Both 

vehicles are driven at a constant speed 

of 72.4 kph (45 mph) and are positioned 

such that the frontmost part of the POV 

is 1.0 m (3.3 ft.) ahead of the rearmost 

part of the SV. After 3.0 s of steady-state 

driving, the POV enters (i.e., converges 

into) the SV’s blind zone by making a 

single lane change into the lane 

immediately adjacent to the SV using a 

lateral velocity of 0.25 to 0.75 m/s (0.8 

to 2.5 ft./s). The period of steady-state 

driving resumes for at least another 3.0 

s and then the POV exits (i.e., diverges 

from) the SV’s blind zone by returning 

to its original travel lane using a lateral 

velocity of 0.25 to 0.75 m/s (0.8 to 2.5 

ft./s). This test is repeated for a POV 

approach from both the left and the 

right side of the SV. 

—To pass a test trial, during the 

converge lane change, the BSW 

must be presented by a time no later 

than 300 ms after any part of the 

POV enters the SV blind zone and 

must remain on while any part of 

the POV resides within the SV 

blind zone. Additionally, during the 

diverge lane change, the BSW may 

remain active when the lateral 

distance between the SV and POV 

is greater than 3 m (9.8 ft.) but less 

than or equal to 6 m (19.7 ft.). The 

BSW shall not be active once the 

lateral distance between the SV and 

POV exceeds 6 m (19.7 ft.). 

• Straight Lane Pass-by Test—The 

POV approaches and then passes the SV 

while being driven in an adjacent lane. 

For each trial, the SV is traveling at a 

constant speed of 72.4 kph (45 mph) 

whereas the POV is traveling at one of 

four constant speeds: 80.5, 88.5, 96.6, or 

104.6 kph (50, 55, 60, or 65 mph). The 

lateral distance between the two 

vehicles, defined as the closest lateral 

distance between adjacent sides of the 

two-dimensional polygons used to 

represent each vehicle’s dimensions, 

shall nominally be 1.5 m (4.9 ft.) for the 

duration of the trial. This test is 

repeated for a POV approach towards 

the SV from an adjacent lane to the left 

and to the right of the SV. 

—To pass a test trial, the BSW must 

be presented by a time no later than 

300 ms after the frontmost part of 

the POV enters the SV blind zone 

and remain on while the frontmost 

part of the POV resides behind the 

frontmost part of the SV blind zone. 

The BSW shall not be active once 

the longitudinal distance between 

the frontmost part of the SV and the 

rearmost part of the POV exceeds 

the BSW termination distance 

specified for each POV speed. 


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POV 

POV converge and diverge lateral velocities, i : assessed over the lane line: t 

:,~·---~=-::~!:.:~~::::;:.:~.,, ...... J ...... --, .. ,J-

. (3\~.J t+-· I 

.,~~•.~,~--

Lateral distance ·i 

before converge onset f ,.; >4 m (13.1 ft.) 1 - '\;>~,"',11•~!0f"l .. ~l~l!'!it""'--•~ 

sv 

i -1--~·---

' Lateral distance after 

diverge completion 

>6m(19.7ft.) 

Figure 13: Straight Lane Converge and Diverge Test, Showing Converge and Diverge from 

the Left 
96022 Federal Register / Vol. 89, No. 232 / Tuesday, December 3, 2024 / Notices 

304Test reports detailing the results for this 

research can be found in docket NHTSA–2021– 

0002. 

NHTSA’s proposed test procedure 

stipulates that each scenario be tested 

using seven repeated trials for each 

combination of approach direction (left 

and right side of the SV) and test speed. 

This translates to a total of 14 tests 

overall for the Straight Lane Converge 

and Diverge Test and 56 tests overall for 

the Straight Lane Pass-by Test. In its 

RFC notice, the Agency proposed that 

the SV must pass at least five out of 

seven trials conducted for each 

approach direction and test speed to 

pass the NCAP system performance 

requirements. Tests that NHTSA 

proposed for NCAP BSW testing are 

shown below in Table 21. 

TABLE 21—BLIND SPOT WARNING (BSW) PROPOSED TEST CONDITIONS

Test scenario SV speed 

(kph (mph)) 

POV speed 

(kph (mph)) 

POV direction 

of approach Turn signal Number of trials 

Straight Lane Converge and Diverge ................................. 72.4 (45) 72.4 (45) Right ..............

Left .................

Disabled .........

Disabled .........

7 

7 

Straight Lane Pass-by ......................................................... 72.4 (45) 80.5 (50) Right ..............

Left .................

Disabled .........

Disabled .........

7 

7 

72.4 (45) 88.5 (55) Right ..............

Left .................

Disabled .........

Disabled .........

7 

7 

72.4 (45) 96.6 (60) Right ..............

Left .................

Disabled .........

Disabled .........

7 

7 

72.4 (45) 104.6 (65) Right ..............

Left .................

Disabled .........

Disabled .........

7 

7 

Model Year 2019 and 2020 Research 

Testing 

In 2020, NHTSA utilized its proposed 

BSW test procedure to conduct a series 

of tests on 10 model year 2019 and 2020 

vehicles to evaluate then-current BSW 

systems.304 The Agency selected test 

vehicles equipped with BSI technology, 

and the same vehicles were also 

subjected to BSI testing, as detailed in 

the next section. 

The Agency’s testing showed that 

most of the model year 2019 and 2020 

vehicles failed at least one trial 

throughout the course of testing. Half of 

the vehicles (five out of ten) only failed 

trials for one of the two test scenarios 

(i.e., either the Straight Lane Pass-by test 

or the Straight Lane Converge and 

Diverge Test). Additional data findings 

will be discussed in the sections to 

follow. 

2. Blind Spot Intervention (BSI) 

Blind spot intervention (BSI) systems 

are similar to AEB systems in that they 

provide active intervention to help the 

driver avoid a collision with another 

vehicle. While BSW systems alert a 

driver that another vehicle is in their 

vehicle’s blind spot, BSI systems 

automatically provide a steering input 

to guide the driver’s vehicle back into 

the unobstructed lane when the BSW is 

ignored and/or apply the vehicle’s 

brakes. Thus, BSI systems actively 

intervene to help a driver avoid 

collisions with other vehicles that are 

approaching or operating within the 

vehicle’s blind spot. 

Like BSW systems, BSI systems 

utilize rear-facing sensors to detect other 

vehicles next to or behind the vehicle in 

adjacent lanes. Depending on the design 

of these systems, BSI activation may or 

may not require the driver to operate 

their turn signal indicator during a lane 

change. In addition, some BSI systems 

may only operate if the vehicle’s BSW 

system is also enabled. 


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Latenildistance during 

validity-period: 

1.5 m {4.9 ft.) 

80.5, 88.5, 96.6, or 104.6 km/h {50, 55, 60, or 65 m 

------------------------- Iii 

72.4km/h (45rnph) 

Figure 14: Straight Lane Pass-by Test, Showing Left-side POV Pass-by 
Federal Register / Vol. 89, No. 232 / Tuesday, December 3, 2024 / Notices 96023 

305Leslie, A.J., Kiefer, R.J., Meitzner, M.R., & 

Flannagan, C.A. (2019), Analysis of the field 

effectiveness of General Motors production active 

safety and advanced headlighting systems, The 

University of Michigan Transportation Research 

Institute and General Motors LLC, UMTRI–2019–6. 

306 ‘‘Manual’’ refers to an externally commanded 

steering input. NHTSA will use a steering robot for 

such inputs to maximize accuracy, repeatability, 

and test efficiency. 

Unlike BSW systems, BSI systems are 

not widely available in the current fleet, 

with only 29 percent of model year 2024 

vehicles equipped with BSI systems as 

standard equipment. NHTSA is unaware 

of any effectiveness studies for this 

technology, which is only beginning to 

penetrate the fleet. Nonetheless, as 

mentioned previously, the Agency 

expects that active safety technologies 

are more effective than warning 

technologies. For example, UMTRI’s 

study of 2013–2017 GM vehicles 

concluded that AEB is more effective 

than FCW alone, and that LKA is more 

effective than LDW.305 The same 

relationship will likely hold true for 

blind spot systems, and that BSI will be 

more effective than BSW alone. Also, 

adopting ADAS technologies such as 

BSI into NCAP should encourage the 

development and robustness of 

enhanced BSW system capabilities (e.g., 

motorcycle and bicycle detection). 

By including BSI as a recommended 

technology in NCAP, NHTSA 

anticipates manufacturers will equip a 

larger portion of the fleet with BSI 

systems. Furthermore, by adopting 

objective test procedures to gauge 

system performance for NCAP’s 

assessments, the Agency will best 

ensure that future BSI systems most 

effectively address the safety need 

stemming from lane change and merge 

crashes. 

Proposed BSI Test Procedure 

NHTSA proposed to use its published 

draft test procedure titled, ‘‘Blind Spot 

Intervention System Confirmation 

Test,’’ to evaluate the performance of 

vehicles equipped with BSI technology 

in NCAP. The Agency’s test procedure 

consists of three scenarios: SV Lane 

Change with Constant Headway, SV 

Lane Change with Closing Headway, 

and SV Lane Change with Constant 

Headway, False Positive Assessment. In 

the first two scenarios, a test vehicle 

(SV) initiates a lane change into an 

adjacent lane while a single other 

vehicle (POV) resides within the SV’s 

blind zone (Scenario 1) or approaches it 

from the rear (Scenario 2). The third 

scenario is used to evaluate the 

propensity of a BSI system to activate 

inappropriately in a non-critical driving 

scenario that does not present a safety 

risk to the occupants in the SV. In each 

of the tests, the POV is a strikeable 

vehicle test device with the 

characteristics of a compact passenger 

car. The SV’s turn signal is activated in 

each test trial. A short description of 

each test scenario and the proposed 

evaluation criteria are detailed below. 

—SV Lane Change with Constant 

Headway Test—The POV is driven 

at 72.4 kph (45 mph) in a lane 

adjacent and to the left of the SV 

also traveling at 72.4 kph (45 mph) 

with a constant longitudinal offset 

such that the frontmost part of the 

POV is 1 m (3.3 ft.) ahead of the 

rearmost part of the SV, which is 

laterally offset from the center of its 

travel lane. After a short period of 

steady-state driving, the SV driver 

engages the left turn signal 

indicator at least 3 s after all pre-SV 

lane change test validity criteria 

have been satisfied. Within 1.0 ± 0.5 

s after the turn signal has been 

activated, the SV driver initiates a 

manual 306 lane change, and follows 

an 800 m (2,625 ft.) radius curved 

path towards the POV’s travel lane. 

The SV driver then releases the 

steering wheel within 250 ms of the 

SV exiting the curve so as to 

achieve a steady state lateral 

velocity of 0.7 ± 0.1 m/s (2.3 ± 0.3 

ft./s) relative to the line separating 

the SV and POV travel lanes. To 

pass a test trial, the BSI system 

must intervene to prevent any 

contact between the SV and the 

POV. Additionally, the SV BSI 

intervention shall not cause a 

secondary departure (i.e., the SV 

BSI intervention shall not cause the 

SV to travel 0.3 m (1.0 ft.) or more 

beyond the inboard edge of the lane 

line separating the SV travel lane 

from the lane adjacent and to the 

right of it within the validity 

period). 

• SV Lane Change with Closing 

Headway Test—The POV is driven at a 

constant speed of 80.5 kph (50 mph) 

towards the rear of the SV in an adjacent 

lane to the left of the SV, which is 

laterally offset from the center of its 

travel lane and traveling at a constant 

speed of 72.4 kph (45 mph). During the 

test, the SV driver engages the left turn 

signal indicator when the POV is 4.9 ± 

0.5 s from a vertical plane defined by 

the rear of the SV and perpendicular to 

the SV travel lane. Within 1.0 ± 0.5 s 

after the turn signal has been activated, 

the SV driver initiates a manual lane 

change and follows an 800 m (2,625 ft.) 

radius curved path towards the POV’s 

travel lane. The SV driver then releases 

the steering wheel within 250 ms of the 

SV exiting the curve so as to achieve a 

steady state lateral velocity of 0.7 ± 0.1 

m/s (2.3 ± 0.3 ft./s) relative to the line 

separating the SV and POV travel lanes. 

—To pass a test trial, the BSI system 


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POV 

i 

- ! i 

~-~-----------------· ..... -- ... 1.om l•---.. --•f 

(3.3 ft.) li. ',-ye,,,~~-

............................ ___ ,..... -.... sv ~~-----,-------------------

Figure 15: SV Lane Change with Constant Headway Test 
96024 Federal Register / Vol. 89, No. 232 / Tuesday, December 3, 2024 / Notices 

307Society of Automotive Engineers (SAE) 

Standard J3016_202104, Taxonomy and Definitions 

for Terms Related to Driving Automation Systems 

for On-Road Motor Vehicles. 

must intervene to prevent any 

contact between the SV and the 

POV. Additionally, the SV BSI 

intervention shall not cause a 

secondary departure (i.e., the SV 

BSI intervention shall not cause the 

SV to travel 0.3 m (1.0 ft.) or more 

beyond the inboard edge of the lane 

line separating the SV travel lane 

from the lane adjacent and to the 

right of it within the validity 

period). 

• SV Lane Change with Constant 

Headway, False Positive Assessment 

Test—The POV is driven at 72.4 kph (45 

mph) in a lane that is two lanes to the 

left of the SV’s initial travel lane with 

a constant longitudinal offset such that 

the frontmost part of the POV is 1 m (3.3 

ft.) ahead of the rearmost part of the SV. 

The SV is laterally offset from the center 

of its travel lane and also travelling at 

72.4 kph (45 mph). The SV driver 

engages the left turn signal indicator at 

least 3 seconds after all pre-SV lane 

change test validity criteria have been 

satisfied. Within 1.0 ± 0.5 seconds after 

the turn signal has been activated, the 

SV driver initiates a manual lane 

change, and follows a defined path into 

the left adjacent lane (the one between 

the SV and POV), approaching the 

center lane line at a constant lateral 

velocity of 0.7 ± 0.1 m/s (2.3 ± 0.3 ft./ 

s). For this test, the driver does not 

release the steering wheel. 

—To pass a test trial, the SV’s BSI 

system must not intervene during 

any valid trials; the lane change 

will not result in an SV-to-POV 

impact. To determine whether a BSI 

intervention occurred, the yaw rate 

data collected for the SV during the 

individual trials performed in this 

scenario are compared to a baseline 

composite. After being aligned in 

time to the baseline, the difference 

between the data must not exceed 1 

degree/second within the test 

validity period. 

Currently, for the three BSI test 

scenarios, specific test procedures and 

specifications are dependent upon the 

SAE Driving Automation Level being 

assessed.307 The four driving 

automation conditions included in the 

test procedure are: (1) with manual 

speed control and Lane Centering 

Assistance (LCA) off (SAE Driving 

Automation Level 0), (2) with cruise 

control enabled and LCA off (also 

considered SAE Level 0), (3) with ACC 


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POV 

1.om 

(3:.3ft.) 

... - - ..., -·- ~ -...... -._, --·-- .... -... --·~- ... ..,.. ..... 

POV 

1.0rn 

(3.3 ft.) 

Figure 16: SV Lane Change with Closing Headway Test 

--

Figure 17: SV Lane Change with Constant Headway, False Positive Assessment Test 
Federal Register / Vol. 89, No. 232 / Tuesday, December 3, 2024 / Notices 96025 

308Test reports detailing the results for this 

research can be found in docket NHTSA–2021– 

0002. 

309The posted speed limit was either not reported 

or was unknown in 2 percent of fatal lane change 

crashes and 18 percent of lane change crashes that 

resulted in injuries. 

310The lane change pre-crash scenarios 

referenced included (1) turning/same direction, (2) 

parking/same direction, (3) changing lanes/same 

direction, and (4) drifting/same direction crashes. 

311The travel speed was either not reported or 

was unknown in 60 percent of fatal lane change 

crashes and 68 percent of lane change crashes that 

resulted in injuries. 

312Swanson, E., Foderaro, F., Yanagisawa, M., 

Najm, W.G., & Azeredo, P. (2019, August), Statistics 

of light-vehicle pre-crash scenarios based on 2011– 

2015 national crash data (Report No. DOT HS 812 

745), Washington, DC: National Highway Traffic 

Safety Administration. 

313 It was unknown or not reported whether 

speeding was a factor in 3 percent of fatal lane 

change crashes and 7 percent of lane change crashes 

that resulted in injuries. 

314Roadway alignment was unknown or not 

reported in 1 percent of fatal lane change crashes 

and 4 percent of lane change crashes that resulted 

in injuries. 

315Roadway grade was unknown or not reported 

in 5 percent of fatal lane change crashes and 18 

percent of lane change crashes that resulted in 

injuries. 

enabled and LCA off (SAE Level 1), and 

(4) with ACC on and LCA on (initially) 

and an automatic SV lane change occurs 

(SAE Levels 2 or 3). For condition 4, SV 

lateral lane position and lane change/ 

path tolerance specifications are 

controlled by the vehicle, not the driver. 

In its March 2022 RFC notice, NHTSA 

stated that it plans to use the [ABD] 

GVT Revision G as a strikeable vehicle 

test device when BSI is added to NCAP 

as a recommended ADAS technology to 

be consistent with Euro NCAP’s ADAS 

test procedures that specify a strikeable 

vehicle test device. 

Tests that NHTSA proposed to 

complete for NCAP BSI testing are 

shown below in Table 22. 

TABLE 22—BLIND SPOT INTERVENTION (BSI) PROPOSED TEST CONDITIONS

Test scenario SV speed 

(kph (mph)) 

POV speed 

(kph (mph)) 

Lane change 

direction Turn signal Number of trials 

SV Lane Change with Constant Headway ..................... 72.4 (45) 72.4 (45) Left ................... Enabled ............ 7 

SV Lane Change with Closing Headway ....................... 72.4 (45) 80.5 (50) Left ................... Enabled ............ 7 

SV Lane Change with Constant Headway, False Positive Assessment.72.4 (45) 72.4 (45) Left ................... Enabled ............ 7 

Model Year 2019 and 2020 Research 

Testing 

NHTSA utilized its proposed BSI test 

procedure to conduct a series of 

research tests on model year 2019 and 

2020 vehicles to assess the performance 

of then-current BSI systems.308 When 

selecting vehicles for testing, an attempt 

was made to choose one test vehicle 

from as many manufacturers as possible 

that had implemented BSI technology at 

the time. As mentioned previously, 

selected vehicles were also subjected to 

BSW testing. An ABD GVT Revision G 

represented the POV during testing. 

Results from this test series suggested 

there is an opportunity for performance 

improvement, as most vehicles failed 

both the SV Lane Change with Constant 

Headway Tests and the SV Lane Change 

with Closing Headway Tests. 

B. Linking Proposed BSW and BSI Test 

Scenarios to Real-World Crashes 

As mentioned in the March 2022 RFC 

notice, the BSW and BSI tests proposed 

by the Agency represent pre-crash 

scenarios that correspond to a 

substantial portion of fatalities and 

injuries observed in real-world lane 

change crashes. A review of Volpe’s 

2011–2015 data set showed that, for 

crashes where posted speed limit was 

known, approximately 29 percent of 

fatalities and 70 percent of injuries in 

lane change crashes occurred on roads 

with posted speeds of 72.4 kph (45 

mph) or lower.309 310 For crashes where 

the travel speed was reported in FARS 

and GES, approximately 44 percent of 

fatalities and 81 percent of injuries 

occurred at speeds of 72.4 kph (45 mph) 

or lower.311 Volpe found that speeding 

was a known factor in 18 percent of the 

fatal lane change crashes and 3 percent 

of lane change crashes that resulted in 

injuries. This suggests that posted speed 

may correspond well to travel speed in 

most lane change crashes.312 313

Roadway alignment and grade for 

real-world lane change crashes also 

align with those used in NHTSA’s 

procedures. For those crashes where 

roadway alignment was known in 

Volpe’s 2011–2015 FARS and GES data 

set, 88 percent of fatal and 93 percent 

of injurious lane change crashes 

occurred on straight roads.314

Furthermore, 77 percent and 86 percent 

of fatal and injurious lane change 

crashes, respectively, occurred on level 

roadways.315

C. Summary of Comments, Response to 

Comments, and Agency Decisions 

1. Blind Spot Technology Inclusion in 

General 

The Agency noted that commenters 

overwhelmingly supported the addition 

of BSW in response to its December 

2015 notice regarding NCAP updates, 

and these sentiments were reiterated in 

the comments received in response to 

the March 2022 RFC notice. Many 

groups and individuals submitted 

comments supporting inclusion of both 

BSW and BSI in NCAP. MEMA 

expressed that BSW and BSI offer 

‘‘significant’’ safety benefits. ITS 

America agreed that NHTSA provided 

sufficient evidence for benefits. 

Advocates and CFA noted that the test 

criteria seemed reasonable and that 

automatic intervention with BSI will 

provide greater benefits than BSW 

alone. 

Honda supported the eventual 

inclusion of BSW and BSI technologies 

based on potential benefits but 

requested that NHTSA use a phased 

approach when adding these 

technologies to NCAP. The automaker 

further noted that the Agency included 

the warning technologies LDW and 

FCW first before proposing to add the 

respective active technologies, LKA and 

AEB, in NCAP. Thus, the Agency 

should consider following the same 

process for blind spot technologies. 

Although Honda acknowledged that 

‘‘active safety technologies are more 

effective than warning technologies,’’ 

the manufacturer stated that it was not 

aware of specific effectiveness data for 

BSI, as it is relatively new compared to 

the other three new technologies 

proposed (i.e., BSW, LKA, and PAEB). 

As such, Honda stated that BSI does not 

fulfill the Agency’s four prerequisites 

for NCAP inclusion at the current time 

and requested that NHTSA wait until 

effectiveness data becomes available for 

BSI before including it in an NCAP 

rating. 

GM and Auto Innovators agreed with 

Honda’s sentiments regarding the 

absence of effectiveness data for BSI. 

However, Auto Innovators 

acknowledged there is some 

effectiveness data available for BSW, 

‘‘depending on system design.’’ The 


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96026 Federal Register / Vol. 89, No. 232 / Tuesday, December 3, 2024 / Notices 

groups also stated that while BSW and 

BSI technologies may be helpful, the 

target populations for BSW and BSI are 

relatively small. Given these concerns, 

Auto Innovators did not support adding 

BSI into an ADAS rating and requested 

that NHTSA include BSI research in the 

NCAP roadmap. However, the group 

had no objection to adding BSI as an 

‘‘NCAP Recommended Technology’’ 

and was not opposed to including BSW 

in the program. Meanwhile, GM did not 

recommend including either BSW or 

BSI. The manufacturer stated that ‘‘any 

future BSI field effectiveness studies 

need to account for redundancies with 

other related ADAS features with 

proven safety benefits, such as LKS, 

LDW, and [GM’s] Lane Change Alert 

(‘‘LCA’’).’’ Regarding BSW inclusion, 

GM shared data from a 2022 

effectiveness study of over 10.9 million 

GM model year 2013 to 2020 vehicles, 

which found that NHTSA’s proposed 

BSW technology did not yield 

statistically significant field safety 

benefits. The automaker asserted that 

‘‘the non-statistically significant level 

observed for [GM’s] BSW (which is a 

short-range detection system) was less 

than half that observed for [the 

manufacturer’s] LCA (which can be 

thought of as ‘‘Long Range’’ BSW), 

which yielded statistically significant 

benefits.’’ 

2. Test Conditions for BSW Testing, 

Including the Straight Lane Pass-by Test 

Scenario With Varying Speed 

Differentials 

As previously described, NHTSA’s 

March 2022 proposal for NCAP BSW 

test scenarios included a Straight Lane 

Converge and Diverge test scenario and 

a Straight Lane Pass-by test scenario. 

Within each scenario, NHTSA proposed 

to perform testing in multiple test 

conditions by varying POV approach 

directions. Within the Straight Lane 

Pass-by scenario, a variety of POV 

speeds were also introduced. 

The Agency also expressed its interest 

in minimizing the testing burden 

whenever possible. As such, NHTSA 

requested comments on whether all test 

conditions should be performed to 

address real-world concerns, and if not, 

which ones should be prioritized. 

Specifically, the Agency mentioned 

possibly incorporating only the most 

challenging test conditions, selecting 

the highest and lowest speed 

conditions, and/or assuming symmetry 

to test only one side of the SV and apply 

results to the other side. 

NHTSA also recognized that lanechange crashes associated with high 

speed differentials between involved 

vehicles may be more severe than those 

in which vehicle speeds are more 

similar. Since the ability to mitigate 

these higher-severity crashes is 

desirable, NHTSA requested comment 

on use of the Straight Lane Pass-by test 

procedure with varying POV-to-SV 

speed differentials to distinguish 

between basic and advanced BSW 

system capabilities. The Agency 

suggested that an SV that can only 

satisfy the BSW activation criteria when 

the POV approaches with a low relative 

velocity may be considered as having 

basic BSW capability, whereas a vehicle 

that can look further rearward to sense 

a passing vehicle travelling at a much 

higher speed may be considered to have 

superior detection abilities. The Agency 

added that the ability of a BSW system 

to provide long-range vehicle detection 

could increase the effectiveness of BSI 

systems and SAE Driving Automation 

Level 2 partial driving automation 

systems that incorporate automatic lane 

change features as well. 

Summary of Comments 

TRC suggested the scenarios proposed 

were sufficient and offered ‘‘good 

coverage’’ of real-world cases. Bosch 

also agreed that both proposed scenarios 

should be included, with the Straight 

Lane Pass-by Test differentiating 

between basic and advanced system 

capabilities and the Straight Lane 

Converge and Diverge Test assessing 

whether the SV can sense POVs 

travelling at the same speed. CAS stated 

it would be premature to only consider 

testing the most stringent scenarios, 

citing concern that manufacturers 

would begin designing to the test rather 

than to a range of conditions. The group 

further stated that the Agency should 

perform all test scenarios and 

conditions to ensure it addresses the 

variety of real-world conditions. Toyota 

noted that it has concerns regarding the 

timely release of information to 

consumers. Toyota also opined that if 

testing at a certain speed or in a specific 

scenario will adequately ensure 

acceptable performance in the entire 

speed range or in all similar cases, the 

Agency should consider running that 

test speed/scenario. 

Tesla recommended NHTSA focus its 

attention on high-risk cases where BSW 

performance tends to be most 

problematic, specifically noting 

situations with a high speed differential. 

Similarly, FCA and Bosch expressed 

favor with testing first at the most 

stringent test case and, should the 

vehicle fail, slowly decreasing the 

stringency until the vehicle passes. The 

manufacturers conveyed that this 

strategy would allow NHTSA to more 

quickly determine the highest speed at 

which the BSW system can reliably 

function. FCA noted that manufacturers 

are most likely already testing their 

vehicles at mid-range speeds to ensure 

system robustness. 

Conversely, ZF Group, ASC, BMW, 

Rivian, Auto Innovators, and Toyota 

recommended that NHTSA test at both 

low and high speeds. ZF Group and 

ASC mentioned that, in cases where 

there is a large performance differential 

between low and high speeds, a midrange test speed may also be 

appropriate. Rivian noted that even with 

a mid-range test added, this strategy 

would result in a reduction of test 

speeds from four to three. Though FCA 

suggested starting at the most stringent 

test case, the automaker also noted that 

the Agency could test at low and high 

speeds as defined by each manufacturer. 

ASC also supported NHTSA 

performing a low-speed SV scenario 

with high relative POV speed to 

approximate cases where the SV is in a 

slower-moving lane but intends to 

change into a faster-moving lane, as is 

the case in traffic congestion. Similarly, 

Vayyar requested that low-speed, or 

even stationary, POV tests be conducted 

to address real-world cases where target 

vehicles are stopped or moving slowly. 

Auto Innovators asserted that the test 

speeds selected should be based on 

several factors: test laboratory 

specifications such as available test lane 

length, real-world crash data, 

capabilities of the POV vehicle test 

device, and the minimum operational 

speed of BSW systems. GM agreed with 

this justification for test speed selection. 

Advocates stated that the chosen 

scenarios and conditions should be able 

to help consumers identify vehicles 

which meet a minimum performance 

and discern between systems of 

minimal and higher performance. 

Regarding symmetry, Toyota 

mentioned left-to-right symmetry 

specifically and suggested that the 

Agency could randomize the test side 

selected to encourage symmetrical 

designs. ZF Group, Tesla, BMW, ASC, 

Auto Innovators, and GM also noted 

that assuming symmetry would reduce 

the number of tests needed, stating data 

could be provided to prove symmetrical 

responses. However, DRI, Rivian, and 

Bosch asserted that NHTSA should still 

consider testing both sides of the 

vehicle. DRI explained that, in its 

experience, BSW performance differs 

from one side of the SV to the other. 

Rivian stated that performance can 

differ between sides due to differences 

in radar hardware location and that 

testing only one side of the vehicle 

might lead to BSW systems that do not 

offer strong real-world safety 


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316The POV selected must be 445 to 500 cm (175 

to 197 in.) in length and 178 to 193 cm (70 to 76 

in.) wide, measured at the widest part of the vehicle 

exclusive of signal lamps, marker lamps, outside 

rearview mirrors, flexible fender extensions, and 

mud flaps. Width is determined with doors and 

windows closed and the wheels in the straightahead position. The color of the vehicle is 

unrestricted. 

performance. Rivian also noted that 

manufacturers may ignore any 

discrepancies in left-to-right side 

design. Finally, Bosch stated both sides 

of the vehicle should be tested to ensure 

system robustness. 

Straight Lane Pass-by Test With Speed 

Differentials To Discern Differences in 

Performance 

Bosch, ZF Group, Toyota, CAS, BMW, 

Tesla, FCA, Auto Innovators, GM, and 

ASC agreed that NHTSA could vary test 

speeds in the Straight Lane Pass-by test 

scenario to differentiate performance 

between vehicles. BMW’s support was 

bolstered by its assertion that the 

Straight Lane Pass-by Test evaluates the 

capability of both hardware (sensor) and 

software (functional logic). ZF Group 

stated that systems which mitigate 

crashes with higher speed differentials 

are more likely to improve safety in a 

broad range of lane-change events and 

therefore should warrant a higher score 

or rating. ASC echoed these sentiments, 

noting that high relative speed 

differentials between lanes can occur 

during real-world driving even though 

speed limits exist because of road work, 

traffic, and other commonly 

encountered scenarios. Further, GM 

suggested 24.1, 32.2, 48.3, and 64.4 kph 

(15.0, 20.0, 30.0, and 40.0 mph) speed 

differentials, and mentioned that, in its 

experience, varying test speeds is not as 

effective at distinguishing BSW 

performance as varying the speed 

differentials between the POV and the 

SV. 

Toyota noted that drivers need as 

much time to react to threats as possible 

and speed-based warning timing is 

preferable since a POV approaching at a 

high speed will require relatively early 

warning. Auto Innovators reiterated this 

by stating that testing at varying speeds 

could differentiate products that offer 

detection within the blind zone only 

(basic performance capability) versus 

products that have an expanded 

rearward field of view to detect a 

vehicle advancing at a higher rate of 

travel (advanced performance 

capability). ASC also discussed this 

expanded rearward field of view, 

detailing the difference between Blind 

Spot Assist (BSA) systems, which are 

meant to mitigate short-range POV–SV 

scenarios, and Lane Change Assist 

(LCA) systems, which address longerrange POV–SV scenarios. The group 

voiced support for both scenarios 

proposed, stating that the Straight Lane 

Converge and Diverge test is a suitable 

evaluation for BSA systems while the 

Straight Lane Pass-by test is best for 

LCA systems. ASC also stated that LCA 

systems are more commonly found in 

countries without posted speed limits, 

whereas BSA is typically offered in 

countries where the posted speed limit 

is 80 mph or less. ASC suggested that, 

in these latter countries, the speed 

differential between lanes and vehicles 

is generally low. Finally, GM stated that 

only long-range LCA systems have been 

shown to reduce feature-relevant lanechange crashes, and therefore, only 

recommended that the Straight Lane 

Pass-by test be performed. 

Response to Comments and Agency 

Decisions 

This notice finalizes NHTSA’s 

proposal including both the Straight 

Lane Converge and Diverge and Straight 

Lane Pass-by scenarios for its BSW tests. 

For the Straight Lane Converge and 

Diverge test (shown in Figure 13), the 

test will begin with the POV two lanes 

away from the SV on a straight road. 

The vehicles will be positioned such 

that the frontmost part of the POV is 1.0 

m (3.3 ft.) ahead of the rearmost part of 

the SV. Both vehicles will be driven in 

this formation at a constant speed of 

72.4 kph (45 mph) for 3.0 seconds. The 

POV will then perform a single lane 

change into the lane adjacent to the SV 

(i.e., the center lane) using a lateral 

velocity of 0.25 to 0.75 m/s (0.8 to 2.5 

ft./s). Once the lane change is 

completed, the POV will continue to be 

driven in the lane adjacent to the SV for 

at least 3.0 seconds, and then will 

perform a lane change back into its 

original outboard lane using a lateral 

velocity of 0.25 to 0.75 m/s (0.8 to 2.5 

ft./s). This test will be repeated for a 

POV approach from both the left and the 

right side of the SV (with and without 

the SV’s turn signal engaged). 

For the Straight Lane Pass-by Test 

(shown in Figure 14), the POV will 

approach and then pass the SV while 

being driven in an adjacent lane on a 

straight road. For each trial, the SV will 

travel at a constant speed of 72.4 kph 

(45 mph) whereas the POV will travel at 

one of four constant speeds: 80.5, 88.5, 

96.6, or 104.6 kph (50, 55, 60, or 65 

mph). The lateral distance between the 

two vehicles will nominally be 1.5 m 

(4.9 ft.) for the duration of each trial. 

This test will be repeated for a POV 

approach towards the SV from an 

adjacent lane to the left and to the right 

of the SV (with and without the turn 

signal engaged). 

The Agency maintains that both of 

these BSW scenarios align with realworld data and are therefore appropriate 

for inclusion in NCAP. As mentioned 

previously, the 72.4 kph (45 mph) SV 

test speed adopted for both BSW 

scenarios proposed was found to cover 

a significant portion of fatalities and 

injuries, and an overwhelming majority 

of lane-change crashes occurred on 

straight roads. The adopted scenarios 

also encompass both ways a vehicle 

may approach another vehicle’s blind 

zone when the driver does not first 

directly see the vehicle: laterally from 

two lanes away and longitudinally from 

behind, on both sides of the vehicle. 

For both test scenarios, the POV is 

defined in NHTSA’s updated BSW test 

procedure as either the ABD GVT 

Revision G or a high-production, 

compact passenger car.316 NHTSA 

added the option to use a surrogate 

vehicle as the POV for BSW testing to 

align with the option provided in its BSI 

testing procedure. However, the Agency 

will use an actual vehicle as the POV 

during BSW testing conducted for 

NCAP assessments. This decision 

should not preclude vehicle 

manufacturers from using the ABD GVT 

Revision G in their internal testing or 

preclude NHTSA from revisiting its 

decision in the future. 

At this time, both BSW test scenarios 

will be conducted during daylight 

conditions only. Real-world crash data 

gathered from 2011 to 2015 suggests that 

most lane-change crashes (62 percent of 

fatal lane-change crashes and 76 percent 

of injurious lane-change crashes) 

occurred annually, on average, during 

daylight hours. For future iterations of 

this consumer information program, 

NHTSA plans to reevaluate the realworld crash data and may adjust the test 

conditions accordingly. 

Straight Lane Converge and Diverge Test 

NHTSA received few comments 

directly related to the Straight Lane 

Converge and Diverge test. Of those 

commenters specifically addressing this 

test scenario, all but GM were in favor 

of its inclusion. Although NHTSA has 

taken into consideration GM’s 

statements that this scenario may be less 

effective at reducing lane change 

crashes compared to the Straight Lane 

Pass-by scenario, the Agency agrees 

with Bosch that the Straight Lane 

Converge and Diverge test will best 

ensure that a vehicle’s BSW system can 

detect a vehicle entering the blind spot 

while both vehicles are travelling at the 

same speed. Since NHTSA found that 

only half of the tested vehicles (five out 

of ten models) passed every trial run 


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317One additional vehicle passed the left POV 

approach direction tests but did not pass one trial 

(of seven) when the POV approached from the right. 

318 In its 2011–2015 data set, Volpe found that for 

the 644,099 lane change crashes occurring annually, 

on average, 752 resulted in a fatality. This translates 

to approximately 526 fatalities that occurred for 

posted speeds exceeding 72.4 kph (45 mph). 

319European New Car Assessment Programme 

(Euro NCAP) (December 2023), Assessment 

Protocol—Safety Assist—Collision Avoidance, 

Version 10.4. 

320A failing result was indicative of the SV’s 

inability to meet performance criteria on the first 

run and/or subsequent runs. 

321NHTSA–2021–0002–0002. 322NHTSA–2021–0002–0002. 

conducted for the Straight Lane 

Converge and Diverge scenario during 

its model year 2019 and 2020 research 

testing series,317 the Agency reasons 

that it is appropriate to move forward 

with including the Straight Lane 

Converge and Diverge test scenario in its 

BSW test series for NCAP to ensure 

adequate BSW system performance for 

this real-world situation. The test will 

be performed four times—twice with the 

POV approaching the SV from the left 

side (once with and once without turn 

signal engagement), and twice with the 

POV approaching from the right, as 

proposed (once with and once without 

turn signal engagement). This should 

ensure that the SV can detect a POV 

entering its blind spot from either lateral 

direction. If the SV does not provide a 

passing warning for a run conducted on 

one side of the vehicle, NHTSA will 

discontinue BSW testing for that vehicle 

model and the test will not be repeated 

for the vehicle’s other side. 

The prescribed test speed for both the 

SV and POV will be 72.4 kph (45.0 

mph), as proposed. In cases where both 

the POV and the SV are traveling at the 

same speed, there is no longitudinal 

speed differential; thus, the speed at 

which the test is conducted is less 

relevant. However, as mentioned, for 

injurious lane-change crashes from 2011 

to 2015 where posted speed limit was 

known, nearly three-quarters (70 

percent) occur on roadways with posted 

speed limits of 72.4 kph (45.0 mph) or 

less on average annually, suggesting that 

the proposed speed is representative of 

real-world crashes. Furthermore, a 72.4 

kph (45.0 mph) test speed is high 

enough that it should exceed most, if 

not all, vehicle models’ BSW minimum 

speeds for activation. Specifically, data 

from the Agency’s annual information 

collection from vehicle manufacturers 

showed a minimum operational speed 

range of 0 to 32 kph (0 to 19.9 mph) for 

model year 2024 vehicles, with the 

average minimum operational speed 

being 10 kph (6.2 mph). The Agency 

also recognizes that a higher test speed 

may require a larger test area, as both 

the POV and the SV must accelerate to 

and maintain the test speed until testing 

is completed. As Auto Innovators and 

GM noted, the Agency is aware that it 

must remain mindful of available test 

laboratory lane length when developing 

test specifications. Given these 

considerations, a test speed of 72.4 kph 

(45.0 mph) for both the POV and the SV 

is reasonable for the Straight Lane 

Converge and Diverge test at this time. 

However, the Agency may consider 

increasing test speeds in the future if 

doing so would better address the large 

percentage of fatalities (i.e., 

approximately 70 percent) in lanechange crashes that occur at higher 

posted speeds, though in relatively low 

numbers.318

Straight Lane Pass-by Test Speeds 

The second BSW test scenario that 

this notice finalizes for inclusion into 

NCAP is the Straight Lane Pass-by test. 

NHTSA notes that Euro NCAP currently 

conducts a Blind-Spot Monitoring 

scenario similar to NHTSA’s Straight 

Lane Pass-by scenario. In the Euro 

NCAP test, a POV passes the SV in an 

adjacent lane; the vehicles travel at 80 

kph (49.7 mph) and 72 kph (44.7 mph), 

respectively. Vehicles receive points 

toward Euro NCAP’s Human Machine 

Interface (HMI) score if the vehicle 

provides continuous visual blind spot 

status information while the POV 

resides in the SV’s designated blind spot 

area.319 NHTSA’s procedure expands 

upon the Euro NCAP procedure through 

the inclusion of three additional higher 

POV speeds, which increase the speed 

differential between the POV and SV. 

Four separate conditions are conducted 

in total, with SV/POV speeds of 72.4/ 

80.5, 72.4/88.5, 72.4/96.6, and 72.4/ 

104.6 kph (45.0/50.0, 45.0/55.0, 45.0/ 

60.0, and 45.0/65.0 mph, respectively). 

These SV/POV speed pairs result in 

speed differentials equaling 8.1, 16.1, 

24.2, and 32.2 kph (5.0, 10.0, 15.0, and 

20.0 mph), respectively. 

The Agency acknowledges several 

commenters suggested a reduction in 

the number of test conditions for the 

Straight Lane Pass-by test to reduce test 

burden. However, NHTSA’s BSW 

research test data from model year 2019 

and 2020 vehicles demonstrates the 

need for testing across all proposed 

speed combinations. Specifically, two of 

the ten vehicle models tested passed the 

lowest 8.1 kph (5 mph) speed 

differential test but failed 320 all 

remaining higher speed differential 

tests.321 Further, two of the remaining 

eight vehicle models failed when tested 

at the lowest speed differential (8.1 kph, 

or 5 mph), while successfully passing 

all higher speed differential tests. 

Further, of the remaining six vehicles, 

one passed the highest speed 

differential test (32.2 kph, or 20 mph) 

but failed tests in at least one low-tomid-range speed differential.322 This 

demonstrates that not all current BSW 

systems struggle more with greater 

speed differential pass-by tests. The 

most stringent test case, albeit a lower 

or higher speed differential, is unclear. 

It may be true, as FCA suggested, that 

vehicle manufacturers test their own 

vehicles at mid-range speeds. However, 

NHTSA will evaluate all four proposed 

test speed pairings to better evaluate 

BSW performance in straight lane passby conditions where the SV is traveling 

at a moderate speed. 

Despite the recommendation of 

several commenters, the Agency is not 

adopting additional test conditions that 

include higher speed differentials for its 

Straight Lane Pass-by tests. This is 

because to increase the speed 

differential between the SV and the 

POV, either the SV speed must be 

reduced or the POV speed must be 

increased. A reduction of the SV speed 

is inappropriate at this time because 

many BSW systems have minimum 

speed thresholds which would not be 

met at a lower speed. Increasing the 

POV speed also does not currently seem 

feasible because test facilities may not 

have adequate lane length available to 

conduct valid tests. Furthermore, the 

Agency did not initially propose higher 

speed test conditions, and it has not 

conducted research tests to evaluate 

cases where the speed delta is greater 

than 32.2 kph (20.0 mph). The Agency 

may adjust the Straight Lane Pass-by 

test conditions in the future when 

laboratory testing proves feasible. 

Further, the Agency is not adopting a 

test condition where the SV is traveling 

at very low speed and contemplating a 

lane change into a much faster-flowing 

lane, despite the request of several 

commenters. These cases occur when 

traffic flow in a travel lane is slowed 

(e.g., increased traffic, construction, or 

there is a disabled vehicle ahead). As 

mentioned, there are a range of 

minimum operating speeds for BSW 

systems, some of which are likely higher 

than the speed at which a vehicle in this 

presented stop-and-go scenario would 

be traveling. For instance, in data 

supplied by vehicle manufacturers for 

the model year 2024 fleet, the Agency 

found that, for those vehicles equipped 

with a BSW system, approximately 12 

percent have a minimum BSW operating 

speed exceeding 20 kph (12.4 mph). 

Further, additional research would need 


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323Of the 10 vehicle models, six failed more trials 

in right POV approach conditions than ones where 

the POV approached from the left. Conversely, one 

failed more trials for left approach conditions, and 

the remaining three performed approximately the 

same left-to-right. 

to be conducted to better understand the 

conditions, frequency, and severity of 

this crash problem. This is because 

unlike other scenarios, posted speed 

limits for the roads on which this type 

of scenario occurs likely do not correlate 

with the travel speed of the SV prior to 

attempting a lane change due to the 

unexpected nature of the situation. 

Thus, travel speed must be used to 

understand the scope of the problem but 

is unknown for many crash cases. Crash 

data from 2011–2015 does show that in 

16 percent of fatal lane change/merge 

crashes and in 23 percent of injurious 

crashes, travel speed was 64.4 kph (40.0 

mph) or lower. However, in 60 percent 

of fatal crash cases and 68 percent of 

injurious crashes, the travel speed prior 

to the crash was unknown. 

For NCAP’s Straight Lane Pass-by 

testing, NHTSA will conduct the lowest 

speed differential condition (SV/POV 

speeds of 72.4/80.5 kph (45.0/50.0 

mph)) first. If the SV provides a passing 

warning during the run, the POV speed 

will incrementally increase by 8.0 kph 

(5.0 mph) and testing will continue, 

with one run conducted per speed 

differential condition (each with and 

without the turn signal engaged), until 

a POV speed of 104.6 kph (65.0 mph) is 

reached. Testing will then be repeated 

following a similar methodology for 

POV movement on the opposite side of 

the SV. If, for any speed differential 

condition, the SV does not provide a 

passing warning, NHTSA will 

discontinue BSW testing for that vehicle 

model. Test runs for a given speed 

differential will not be repeated upon a 

vehicle’s failure to appropriately warn— 

a methodology consistent with that used 

for NCAP’s AEB and PAEB performance 

evaluations. This test methodology 

aligns with those adopted for the other 

NCAP AEB and PAEB tests, in which 

the Agency chose an incremental 

approach to increasing test speeds. 

Differentiating BSW System 

Performance 

NHTSA will not differentiate BSW 

system performance with this upgrade. 

A vehicle passing three of the four test 

speed conditions in the Agency’s 

Straight Lane Pass-by test will not 

receive more credit than a vehicle that 

passes two. Instead, a vehicle will need 

to pass all four Straight Lane Pass-by 

tests for both sides of the vehicle (with 

and without the turn signal engaged) 

and the Straight Lane Converge and 

Diverge test for both sides of the vehicle 

(with and without the turn signal 

engaged) to receive credit for its BSW 

system. Based on this, NHTSA 

concludes that FCA and Bosch’s 

suggestion to determine the highest 

speed at which BSW can function is 

unnecessary. This decision still 

encourages manufacturers to include 

technology addressing a range of lanechange events, as ZF Group requested, 

because it ensures that the vehicle must 

pass all BSW test conditions for each of 

the two test scenarios. Further, as ASC 

asserted, by including the Straight Lane 

Converge and Diverge test in addition to 

the Straight Lane Pass-by test, as well as 

both low and high speed differential 

conditions for the latter, NHTSA will be 

able to effectively assess performance 

for a variety of BSW system types (e.g., 

BSA and LCA). Specifically, for the 

Straight Lane Converge and Diverge test, 

the SV must detect a POV travelling at 

the same speed at a close distance, and 

BSA systems can best address such 

situations. For the Straight Lane Pass-by 

test, the SV must detect a faster-moving 

POV farther away to issue the BSW at 

the appropriate time, and LCA systems 

are best able to address these 

conditions. Thus, the Agency’s BSW 

testing will ensure vehicles’ BSW 

systems provide acceptable 

functionality to cover this range of realworld situations. 

NHTSA will not tailor testing to each 

manufacturer or model but will instead 

apply the same test conditions to each 

vehicle model assessed. A methodology 

allowing each manufacturer to supply 

its own minimum and maximum POV 

speeds for the Agency’s assessments, as 

suggested by FCA, would not evaluate 

models with the same degree of 

stringency, confounding attempts for 

consumers to compare vehicles side-byside and leading to consumer confusion 

and misrepresentation. 

Testing for Symmetrical System 

Responses 

The Agency will not assume a 

symmetrical BSW response by testing 

only one side of the SV. In NHTSA’s 

model year 2019 and 2020 BSW 

research test series, four out of ten 

vehicle models failed to provide a 

passing warning during at least one trial 

when the POV approached one side of 

the vehicle but not the other for a 

particular test condition. These findings 

bolster DRI’s comment that BSW 

performance differs depending on 

which side is tested. Overall, for a given 

vehicle model, the right POV approach 

condition seemed more challenging 

than the left POV approach condition, 

but this was not universally true.323

Thus, without a comprehensive 

assessment of left-to-right performance, 

NHTSA cannot confirm equivalent, 

robust system performance. Other 

approaches suggested, such as random 

selection of sides and/or using 

manufacturer-supplied data to 

determine symmetry, introduce a level 

of subjectivity. Due to the high 

percentage of vehicle models tested by 

NHTSA which did not offer 

symmetrical performance across all five 

test scenarios for BSW, the Agency is 

hesitant to allow testing of only side of 

the vehicle at this time. This is subject 

to change in the future as vehicle 

hardware and software evolves. 

3. Use of the Turn Signal for BSW 

BSWs are automatically presented to 

the driver when another vehicle is 

operated in, or approaching, the driver’s 

blind spot. These alerts may be visual 

(most common), haptic, or auditory. 

When the driver engages the turn signal 

to initiate a lane change in the direction 

of a vehicle in the adjacent lane, 

additional, escalated alerts may also 

activate to warn the driver more 

urgently that there is already a vehicle 

present. 

NHTSA’s current BSW test procedure 

does not stipulate turn signal activation 

during BSW testing. However, in its 

RFC notice, the Agency sought 

comments on whether the turn signal 

indicator should be engaged, with the 

intent to evaluate the additional alerts 

presented to a driver intending to make 

a lane change rather than only the 

automatic alert presented whenever 

another vehicle is occupying the blind 

spot area. If commenters were interested 

in testing with the turn signal enabled, 

the Agency requested further comments 

regarding the type of alerts that should 

be required (e.g., visual, haptic, and/or 

auditory) and the distinction between 

alerts issued with and without turn 

signal usage. 

Summary of Comments 

Turn Signal Activation 

Several commenters stated that the 

BSW system should be evaluated both 

with and without the use of the turn 

signal indicator during testing. ZF 

Group reasoned that both conditions 

should be tested because crashes can 

occur regardless of whether the turn 

signal is activated. ASC suggested that 

testing in both configurations can 

determine whether ‘‘the BSW warning is 

being suppressed for planned lane 

changes where the turn signal indicator 

is activated.’’ Rivian commented that 

NHTSA should run a limited number of 

tests involving the use of the turn signal 


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only to ‘‘verify functional logic.’’ HATCI 

requested that finalized test procedures 

be made available before making a 

decision regarding turn signal usage but 

commented that the procedures should 

be flexible to accommodate. 

While some commenters requested 

use of the turn signal during testing, 

many stated that testing without the 

turn signal is critical. CAS and others 

commented that the presence of a 

vehicle may inform the driver’s decision 

to initiate a lane change. Commenters 

further stated that omitting the turn 

signal more closely represents actual 

driver behavior, as the turn signal is not 

always engaged before making a 

maneuver. Along these lines, one 

individual commented that safety 

assessments should be based on likely 

real-world driver behavior instead of 

idealized behavior. Honda noted that its 

vehicles’ alert timing is independent of 

the driver’s intentions and is based on 

a time-to-collision assessment. Bosch 

stated that, unless NHTSA plans to 

evaluate the warning system itself and 

not whether it triggers, it is not 

necessary to engage the turn signal. 

Alert Type Requirement 

Commenters expressed mixed 

opinions regarding what types of alerts 

should be required if the BSW test 

procedure is modified to require 

activation of the turn signal. 

Any Alert Type 

Some commenters (Honda, Bosch, 

HATCI, and one anonymous individual) 

stated that any alert type should be 

allowed for BSW credit if use of the turn 

signal is stipulated. HATCI expressed 

that allowing any alert modality should 

give manufacturers flexibility to 

optimize alerts based on the ‘‘multitude 

of ADAS technology installed, the 

interactions between the technologies, 

and research and development 

findings.’’ Bosch agreed that flexibility 

was advantageous but added that the 

same alert modalities used for other 

ADAS should not be used for BSW, 

since this may confuse the consumer 

and decrease consumer acceptance. 

Honda commented that there is ‘‘no 

reasonable method to objectively 

evaluate the performance of different 

alert modalities’’ and that doing so 

could complicate the test procedures. 

HATCI suggested that NHTSA ‘‘consider 

researching performance requirements 

to measure effectiveness of alerts rather 

than prescribing specific modes’’ where 

appropriate. Auto Innovators 

acknowledged that, while there is 

potential benefit for an escalating alert 

modality when the turn signal is 

engaged, the Agency should not 

prescribe a specific alert type. 

Visual Warnings 

Many responders commented that 

visual warnings were sufficient (or 

preferred) for BSW systems. Some 

commenters mentioned visual warnings 

can be very effective when placed in a 

natural location for visual checking, 

such as a side mirror. Toyota noted that, 

‘‘in the case that BSW is not activated, 

the driver should be still looking at the 

mirror’’ to scan for other vehicles prior 

to a lane change. Thus, a change in 

desired driver behavior would not be 

required. GM and FCA also alluded to 

the importance of checking mirrors for 

maneuver planning and agreed that 

drivers should be encouraged to check 

mirrors rather than rely solely on other 

cues, such as haptic or auditory 

warnings. GM specified that a steady 

amber warning icon should be visible in 

the side mirror adjacent to the potential 

threat and should flash upon turn signal 

engagement. GM added that mirrorchecking is especially important 

because short-range BSW systems ‘‘have 

limited capability for alerting drivers 

with enough time to react to fast 

approaching traffic.’’ Auto Innovators 

stated that ‘‘visual alerts only are 

sufficient enough for inclusion in NCAP 

for evaluations and effective alert 

methods if they are displayed within the 

driver’s field of view as they check their 

mirror before changing lanes.’’ Tesla 

and FCA agreed that visual BSWs are 

sufficient. 

Haptic Warnings and/or Auditory 

Warnings 

NHTSA received varied support for 

haptic and/or auditory alerts for BSW. 

Some commenters, such as FCA and 

BMW, asserted that auditory warnings 

can become a nuisance. FCA stated its 

research has shown that an auditory 

warning can drive customer 

dissatisfaction when it occurs while 

merging in front of another vehicle and 

can cause the driver to disable the 

feature altogether. FCA stated it allows 

the driver to disable the auditory BSWs 

for this reason. BMW offered that 

drivers often engage their turn signals to 

signal their eventual intent, even when 

they know there is a vehicle in their 

blind spot. BMW reasoned that haptic 

and/or auditory warnings would annoy 

the driver in such instances. GM 

submitted similar sentiments regarding 

non-visual BSWs, stating that such 

alerts would be an annoyance to drivers 

who have no intention of switching 

lanes, or who signal an intent to change 

lanes in advance of an intended lane 

change. 

Other commenters stated they would 

like to see additional alert types used for 

BSW. ZF Group suggested visual 

warnings may be ‘‘more or less effective 

depending on sunlight’’ and that an 

additional alert method might increase 

robustness of the system. ZF Group 

stated that its research suggests that 

haptic seat belt warnings are very 

effective; they added that the use of 

haptic or auditory warnings such as 

those used for LDW could be effective 

because they are meant to convey the 

same underlying information—the SV is 

about to experience a ‘‘potentially 

hazardous’’ lane departure. ASC and 

GM also agreed with these sentiments, 

with GM commenting that a single alert 

type (visual) could be used when the 

alert is ‘‘cautionary,’’ and multiple alert 

modalities can be used when the 

situation is more urgent. CAS also stated 

there should be an auditory or haptic 

warning because the cost of adding 

these alert types to the vehicle would be 

minimal. 

NHTSA received some feedback 

suggesting the type of warning should 

depend on the driver’s intent. IDIADA 

shared that its experience has been that 

visual alerts work best for conveying 

information, not for urgently alerting the 

driver, further noting that an auditory 

warning would be preferable for alerting 

the driver when attempting to perform 

an unsafe lane change. Vayyar agreed 

with this sentiment but suggested that 

either an auditory or haptic alert would 

be acceptable for the warning associated 

with the turn signal. Rivian requested 

allowing users to customize their alert 

type based on driver preference. Rivian 

stated that visual alerts should not be 

allowed to be disabled, but that an 

option for auditory alerts should be 

required and an option for haptic alerts 

should be encouraged. 

Alert Distinctions Between Use and 

Non-Use of Turn Signal 

Regarding distinction between alert 

modalities associated with and without 

the use of the turn signal, as mentioned 

previously, most commenters agreed 

that use of the turn signal should 

increase the ‘‘urgency’’ of the alert 

issued to the driver. Toyota, CAS, ASC, 

ZF Group, Tesla, BMW, FCA, Rivian, 

Bosch, and GM all expressed favor with 

the use of a flashing alert specifically to 

send a more intense signal to the driver 

when the turn signal is used since it 

conveys intent to maneuver. Toyota’s 

reasoning was that a flashing or blinking 

visual warning is normally ‘‘interpreted 

as conveying ‘priority’.’’ Tesla, Auto 

Innovators, and BMW suggested 

providing an escalated alert to the driver 

when another vehicle is detected in the 


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SV’s blind spot and the turn signal is 

engaged. 

Some commenters stated that the 

warning indicator should flash 

regardless of driver intent. CAS 

suggested that LDW/LKA and BSW/BSI 

be integrated so that an ‘‘aggressive 

warning and correction’’ should occur if 

the blind spot is occupied and the 

driver begins to make a hazardous 

maneuver, regardless of turn signal 

status, because the cost of including a 

combined warning is minimal. ASC also 

specified that the warning light should 

flash whether the lane change is 

intentional or not. 

Auto Innovators did not oppose the 

use of a flashing symbol upon activation 

of the turn signal. However, the 

organization relayed that this is not the 

only acceptable alert modality and that 

NHTSA should not restrict performance 

criteria to this type of alert only. 

Advocates also commented that a 

general escalation should be required 

and noted that a flashing visual warning 

would be logical; however, it further 

stated that the Agency should provide 

data to support the alert modality 

ultimately selected to receive credit. 

Response to Comments and Agency 

Decisions 

The Agency has decided to modify its 

BSW test procedure to require 

additional testing with the turn signal 

indicator engaged. NHTSA appreciates 

Bosch’s position that engaging the turn 

signal is seemingly unnecessary since 

the Agency plans to only assess whether 

the warning triggers at the appropriate 

time (i.e., detects the POV when it is in 

the driver’s blind spot) and will not 

evaluate the warning system itself. 

However, the Agency also maintains 

that there is merit to Rivian’s suggestion 

to conduct tests to verify the 

functionality of the BSW system when 

the turn signal is engaged. This 

additional testing should ensure that a 

vehicle still issues a BSW when the 

driver engages the turn signal with the 

intent to switch lanes before fully 

assessing their surroundings, as ASC 

suggested. Further, as BMW and GM 

noted, utilizing the turn signal to notify 

intent is a common practice used by 

drivers. Performing testing both with 

and without the turn signal engaged 

should address the greatest number of 

real-world driving conditions. Although 

several commenters correctly stated that 

many drivers do not use their turn 

signal to indicate intent to change lanes, 

many others do. Receiving an alert 

when another vehicle is present may 

deter this latter group of drivers from 

completing the lane change. Therefore, 

ensuring that a BSW is issued in either 

case seems appropriate. 

For this NCAP upgrade, the Agency is 

requiring that FCWs be comprised of an 

auditory and visual signal but is not 

imposing specific attributes (e.g., size, 

location, decibel level, tactile type, etc.) 

for either signal modality. However, for 

its BSW tests, NHTSA is not only 

implementing a visual alert 

requirement, but it is also imposing 

additional alert specifications. 

Specifically, a visual alert that is 

compliant with SAE Standard J2802, 

‘‘Blind Spot Monitoring System (BSMS): 

Operating Characteristics and User 

Interface’’ must be present in the side 

mirror or the A-pillars. The alert must 

meet the timing requirements specified 

in the Agency’s BSW test procedure. 

Although this visual alert requirement 

will apply to tests conducted both with 

and without use of the turn signal, the 

type of visual alert displayed may 

change for tests conducted with turn 

signal engagement. For BSW tests 

conducted without the turn signal 

engaged, the visual warning must be 

continuously illuminated. When the 

turn signal is engaged in the Agency’s 

BSW tests, the visual warning may 

become escalatory in nature (e.g., 

switches from steady-burning to 

flashing, changes color, etc.), or may 

remain continuously illuminated for 

vehicles where a second warning 

modality is also provided. 

While acknowledging the comments 

manufacturers provided promoting 

flexibility to optimize alerts for various 

ADAS technologies, requiring a visual 

alert to appear in the side mirror or Apillar adjacent to the potential crash 

threat is a reasonable minimum NCAP 

requirement for BSW technology, 

particularly since the driver’s gaze when 

considering a lane change should be in 

the direction of the intended lane 

departure. As Toyota, GM, FCA, and 

Auto Innovators mentioned, drivers are 

expected to check their side mirrors or, 

at a minimum, look left or right, as 

appropriate, to check for the presence of 

other vehicles prior to initiating a lane 

change. Warnings should serve to assist 

the driver in detecting the presence of 

vehicles in their blind spots; they 

should not encourage complacency 

during normal driving. With short-range 

detection capabilities, BSW systems 

may not always warn drivers with 

enough time for them to react to fastmoving vehicles, as GM stated. As such, 

NHTSA agrees with commenters that 

the onus remains on the driver to be 

diligent and check their side mirrors 

before changing lanes, even for vehicles 

equipped with BSW systems. 

In addition to the continuously 

illuminated visual cue required for all 

BSW tests performed without the SV 

turn signal engaged, the Agency is 

requiring issuance of an additional alert 

modality (i.e., a dual-modality alert) or 

an escalating visual alert (e.g., switches 

from steady-burning to flashing) upon 

turn signal engagement, as Auto 

Innovators suggested. With the turn 

signal engaged, the driver is signaling an 

intent to change lanes, thus altering the 

significance of the alert from a 

cautionary state to a state of urgency. 

The Agency agrees with GM, IDIADA, 

and Vayyar that a single alert type (i.e., 

visual) may be sufficient when it serves 

to caution the driver; however, multiple 

alert modalities or alerts with escalating 

visual attributes are a more effective 

way to discourage a driver from 

proceeding with an intended action that 

may cause harm. 

NHTSA recognizes that many 

commenters preferred use of a flashing 

visual alert when the turn signal is 

engaged and another vehicle is in or 

approaching the driver’s blind spot. 

Conversely, many others expressed that 

non-visual alert types (e.g., haptic and 

auditory) can be very effective if 

executed properly. In consideration of 

this, the Agency will allow vehicle 

manufacturers to dictate the 

supplemental alert type and/or 

escalation attributes that will be 

required for BSW testing when the turn 

signal is engaged. A vehicle may present 

a BSW that is comprised of a visual and 

auditory or visual and haptic signal, or 

it may simply present an alert that 

exhibits escalating visual attributes. 

Such an approach should allow 

manufacturers to optimize alert 

strategies not only for BSW systems but 

also for other ADAS technologies in the 

future, as many commenters requested. 

Although the Agency recognizes that 

effectiveness may change with flash 

rate, color, etc. for visual warnings; 

frequency, decibel level, etc. for 

auditory warnings; and tactile type (e.g., 

vibration, jerk, etc.) for haptic warnings, 

it will not prescribe such requirements 

at this time. NHTSA has not conducted 

research to guide such prescriptions, 

and, as Honda asserted, it currently has 

no method to objectively evaluate the 

performance of different BSW 

modalities. As such, it does not want to 

impose requirements for additional alert 

types that may be of nuisance and create 

customer dissatisfaction such that 

drivers choose to disable BSW 

functionality. 

Further, the Agency will not require 

the BSW visual cue to flash when the 

driver departs the lane absent turn 

signal engagement, as CAS and ASC 


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324While the Agency did not explicitly discuss 

SAE Driving Automation Level 2 and 3 test scenario 

descriptions for BSI testing in its RFC, the proposed 

test procedures allow for testing of these systems. 

However, the Agency does not anticipate testing 

Level 2 or 3 systems as part of NCAP at this time 

given the limited number of applicable vehicles 

currently available, along with uncertainty about 

the driver and vehicle interaction imposed by such 

implementations. 

325The initial lateral offset of the vehicle from the 

centerline (based on the vehicle width and the 

desired lateral velocity) is to ensure the SV is being 

operated at the desired lateral velocity before BSI 

operates. 

326 ‘‘Manual’’ refers to an externally commanded 

steering input. NHTSA will use a steering robot for 

such inputs to maximize accuracy, repeatability, 

and test efficiency. 

327For the BSI tests, a secondary departure occurs 

when the SV BSI intervention causes the SV to 

travel 0.3 m (1.0 ft.) or more beyond the inboard 

edge of the lane line separating the SV travel lane 

from the lane adjacent and to the right of it (for lane 

changes to the left) or adjacent and to the left of it 

(for lane changes to the right) within the validity 

period. 

suggested, since NHTSA does not want 

to be overly prescriptive for a condition 

that is more representative of its lane 

keeping test scenarios (where lane 

departure is unintentional and thus turn 

signal engagement is not expected) than 

its BSW test scenarios (where lane 

departure is deliberate and thus turn 

signal engagement is likely, though not 

always assured). Although both turn 

signal use and non-use will be 

represented in the Agency’s BSW tests, 

the Agency’s lane keeping tests will be 

conducted without turn signal 

engagement. 

4. Test Conditions for BSI Testing 

In addition to a warning-based blind 

spot assessment, NHTSA also proposed 

an active safety evaluation (i.e., BSI) for 

inclusion in NCAP. Test scenarios 

proposed for BSI include two lane 

change scenarios (SV Lane Change with 

Constant Headway and SV Lane Change 

with Closing Headway) and one false 

positive scenario (SV Lane Change with 

Constant Headway, False Positive 

Assessment), to be discussed later.324

Summary of Comments 

Most respondents to the March 2022 

notice did not solely address BSI, with 

comments generally referring to both 

blind spot technologies (i.e., BSW and 

BSI). However, many commenters did 

express support for inclusion of BSI 

along with BSW. Aptiv, Consumer 

Reports, MEMA, ITS, Advocates, Bosch, 

HMNA, NADA, and two individuals, 

among others, stated approval of 

NHTSA’s plan to evaluate BSI as a part 

of NCAP. Aptiv suggested that the 

proposed parameters would allow 

NHTSA to quantify BSI’s benefits. 

MEMA agreed with NHTSA that all four 

ADAS technologies included as part of 

this final notice, including BSI, are 

mature, and would not only address a 

range of crash scenarios, but also offer 

significant safety benefits. In addition, 

Bosch stated that BSW and BSI may 

both help to reduce the risk of lanechange crashes. 

However, several commenters stated 

that BSI technology is not mature and 

opposed including it in this NCAP 

update. GM, Auto Innovators, and 

Honda suggested that BSI could be 

included in the future, particularly once 

benefits numbers are better established. 

Auto Innovators further clarified that 

NHTSA should not include the BSI 

evaluation in an ADAS rating but that 

the group would find it acceptable to 

include it as a recommended technology 

to encourage BSI adoption. 

On the issue of test speeds, Advocates 

expressed concern that a single SV test 

speed of 72.4 kph (45 mph) would not 

ensure BSI systems operate across an 

appropriate range of speeds. 

Response to Comments and Agency 

Decisions 

Although some commenters opposed 

the immediate inclusion of BSI into 

NCAP, many others were in favor of 

including evaluations for this active 

technology with this program update. 

NHTSA expects that BSI, in tandem 

with BSW systems, will reduce the 

frequency of lane-change crashes. This 

is because active safety technologies are 

thought to be more effective than 

warning technologies alone, so benefit 

estimates for BSI systems should be 

greater than for BSW systems. As such, 

it is prudent to add BSI technology to 

NCAP at this time and NHTSA is 

proceeding with adopting all three 

scenarios proposed for the technology in 

its March 2022 RFC notice—the SV 

Lane Change with Constant Headway 

scenario, the SV Lane Change with 

Closing Headway scenario, and the SV 

Lane Change with Constant Headway 

False Positive scenario. 

For the SV Lane Change with 

Constant Headway Test (shown in 

Figure 15), the POV, driven at the same 

speed of the SV (i.e., 72.4 kph (45 

mph)), is positioned in a lane adjacent 

to that of the SV with a constant 

longitudinal offset from the rearmost 

part of the SV, which is laterally offset 

from the center of its travel lane.325

After a short period of steady-state 

driving, the SV driver (i.e., robot) will 

initiate a manual 326 lane change, 

following an 800 m (2,625 ft.) radius 

curved path towards the POV’s travel 

lane. The SV driver (i.e., steering robot) 

then releases the steering wheel within 

250 ms of the SV exiting the curve so 

as to achieve a steady state lateral 

velocity of 0.7 ± 0.1 m/s (2.3 ± 0.3 ft./ 

s) relative to the line separating the SV 

and POV travel lanes. In response to the 

lane change maneuver, the BSI system 

is expected to intervene and prevent the 

rear of the SV from contacting the front 

of the POV. Additionally, the SV BSI 

intervention must not cause a secondary 

departure.327

For the SV Lane Change with Closing 

Headway Test (shown in Figure 16), the 

POV, approaching the SV from the rear, 

is driven at a constant speed of 80.5 kph 

(50 mph). The POV’s speed is 8 kph (5 

mph) greater than that of the SV, which 

is travelling in an adjacent lane at 72.4 

kph (45 mph), with a lateral offset from 

center. During the test, the SV driver 

(i.e., steering robot) will initiate a 

manual lane change, following an 800 m 

(2,625 ft.) radius curved path towards 

the POV’s travel lane. The SV driver 

(i.e., robot) then releases the steering 

wheel within 250 ms of the SV exiting 

the curve so as to achieve a steady state 

lateral velocity of 0.7 ± 0.1 m/s (2.3 ± 

0.3 ft./s) relative to the line separating 

the SV and POV travel lanes. In 

response to the lane change maneuver, 

the BSI system is expected to intervene 

and prevent the rear of the SV from 

contacting the front of the POV. 

Additionally, the SV BSI intervention 

must not cause a secondary departure. 

For the SV Lane Change with 

Constant Headway, False Positive 

Assessment Test (shown in Figure 17), 

the POV, driven at 72.4 kph (45 mph), 

is positioned in a lane that is two lanes 

to the left or right of the SV’s initial 

travel lane with a constant longitudinal 

offset from the rearmost part of the SV. 

The SV is laterally offset from the center 

of its travel lane and also travelling at 

72.4 kph (45 mph). After a short period 

of steady-state driving, the SV driver 

(i.e., steering robot) will initiate a 

manual lane change into the adjacent 

lane (the one between the SV and POV) 

to either the left or to the right. The SV 

follows a defined path toward the 

adjacent lane, approaching the center 

lane line at a constant lateral velocity of 

0.7 ± 0.1 m/s (2.3 ± 0.3 ft./s). For this 

test, the driver (i.e., robot) does not 

release the steering wheel. Since no 

POV is present in this lane and therefore 

the lane change will not result in an SVto-POV impact, the BSI system must not 

intervene. To determine whether a BSI 

intervention occurred, the yaw rate data 

collected for the SV during the 

individual trials are compared to a 

baseline composite. The difference 

between the data must not exceed 1 


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328These tests are specified in Euro NCAP’s Lane 

Support Systems (LSS) test protocol as part of its 

Emergency Lane Keeping (ELK) test series. 

329For SAE Driving Automation Level 0- or 1- 

equipped vehicles, a result is considered passing 

when (1) the SV intervenes to avoid contact with 

the POV during the test and (2) the intervention 

does not cause the SV to travel more than 0.3 m 

(1.0 ft.) beyond the inboard edge of the lane line 

which separates the SV travel lane from the one 

adjacent and to the right of it within the validity 

period. This must be true for any number of trials 

conducted. 

330European New Car Assessment Programme 

(Euro NCAP) (December 2023), Test Protocol—Lane 

Support Systems, Version 4.3. See section 5. 

331Swanson, E., Foderaro, F., Yanagisawa, M., 

Najm, W. G., & Azeredo, P. (2019, August), 

Statistics of light-vehicle pre-crash scenarios based 

on 2011–2015 national crash data (Report No. DOT 

HS 812 745), Washington, DC: National Highway 

Traffic Safety Administration. 

332A highway was defined as such if all three 

precrash trafficway attributes were true: (1) a posted 

speed limit was ≥ 45 mph; (2) the relation to 

junction was a non-junction, through roadway, or 

other location within an interchange area; and (3) 

the trafficway description was a two-way, divided, 

unprotected (painted > 4 feet) median; two-way, 

divided, positive median barrier; or entrance/exit 

ramp. 

degree/second within the test validity 

period. 

Assessments for each scenario will be 

performed during daylight conditions 

only for a POV approach on both the left 

and right sides of the SV (i.e., the SV 

will make left and right lane changes 

during testing) and with and without 

the turn signal engaged. Tests will be 

conducted without LCA or cruise 

control (i.e., conventional or adaptive 

cruise control, or ACC) engaged. 

The Agency notes that of the three BSI 

test scenarios proposed by NHTSA, two 

closely mirror Euro NCAP’s Overtaking 

Vehicle tests,328 (SV Lane Change with 

Constant Headway scenario and SV 

Lane Change with Closing Headway 

scenario), bolstering support for their 

adoption into U.S. NCAP. Further, 

NHTSA has found feasible BSI testing 

according to the Agency’s draft test 

procedures. Specifically, in its model 

year 2019 and 2020 BSI test series, the 

Agency found that, while no vehicles 

were able to fully and reliably meet 

requirements to pass 329 the SV Lane 

Change with Constant Headway 

scenario, four of the ten were able to 

pass the SV Lane Change with Closing 

Headway test. NHTSA expects that 

vehicle performance will improve over 

time as manufacturers apply strategies 

already in use internationally. 

The Agency will conduct the adopted 

BSI test scenarios using the 72.4 kph (45 

mph) SV proposed speed. The SV Lane 

Change with Closing Headway scenario 

will also retain the 80.5 kph (50 mph) 

POV speed. The rationale for this 

decision is similar to that provided for 

BSW—notably, the speeds’ correlation 

with real-world crash data for injurious 

lane-change crashes and sufficiency for 

minimum activation of blind spot 

systems. Additionally, these test speeds 

were developed to balance the need to 

address a real-world safety problem 

with equipment capabilities dictated by 

the state of technology for the GVT, 

available testing real estate at test 

laboratories, and the Agency’s 

validation efforts (e.g., of the speeds 

accurately and repeatably attainable 

with the robotic platforms used to move 

the GVT during BSI test conduct). 

NHTSA concludes that the 72.4/80.5 

kph (45/50 mph) test speeds best 

achieve this balance. Additionally, Euro 

NCAP’s Lane Support Systems (LSS) 

protocol for the Emergency Lane 

Keeping (ELK) Overtaking Vehicle test 

scenarios includes the same SV and 

POV speeds as those NHTSA has 

specified in its BSI test procedure. 

Having said this, the Agency 

acknowledges Advocates’ concern that a 

single speed may not address a range of 

real-world driving speeds, and NHTSA 

may consider testing at higher SV/POV 

speeds in the future. In addition, the 

Agency may reevaluate this decision in 

the future and adjust the test conditions 

accordingly if real-world crash data 

shows a need for doing so. 

Although the Agency’s draft BSI 

procedure only specified assessments 

for SV lane changes occurring to the left, 

the Agency has decided to perform BSI 

testing for a POV approach on both the 

left and right sides of the SV. This is 

because NHTSA asserts there is reason 

for it to also verify functionality of BSI 

systems when making a right-lane 

change. For example, in real-world 

cases, the SV may be on a multi-lane 

road or be in the left lane of a two-lane 

road and attempting to move right. As 

previously mentioned, during the 

Agency’s model year 2019 to 2020 BSW 

research testing, BSW systems appeared 

to perform either the same or worse 

when the POV approached on the righthand side. Thus, symmetrical responses 

cannot be assumed, and in the interest 

of providing thorough information to 

the consumer, NHTSA will similarly 

assess both left-hand and right-hand BSI 

performance. Though this addition 

deviates from Euro NCAP’s test 

protocol, the Agency concludes that it is 

appropriate given the considerations 

mentioned. 

NHTSA is also adopting ABD GVT 

Revision G for the POV used in its BSI 

tests, as detailed later in this section. 

This test device is the most suitable 

vehicle surrogate for BSI testing given 

its use in NCAP’s BSI tests would 

harmonize with the vehicle test device 

prescribed in Euro NCAP’s LSS testing 

protocol for the organization’s 

Overtaking Vehicle tests and because it 

satisfies the specifications defined in 

ISO 19206–3 (2021).330

At this time, similar to the decision 

for the Agency’s BSW tests, the BSI test 

scenarios will be conducted during 

daylight conditions only. NHTSA made 

this decision because, as mentioned 

previously for BSW, 2011–2015 crash 

data suggests that the majority of lanechange crashes (62 percent of fatal lanechange crashes and 76 percent of 

injurious lane-change crashes) occurred 

annually, on average, during daylight 

hours. The Agency may reevaluate this 

decision in the future and adjust the test 

conditions accordingly if real-world 

crash data shows a need. 

The same tests must be completed for 

each vehicle model assessed for NCAP 

to provide equivalent information 

regarding vehicle performance across 

the fleet. The longitudinal speed of the 

SV will be maintained through manual 

or robotic control during conduct of 

NCAP’s BSI tests. At this time, the 

Agency will not utilize conventional or 

ACC during NCAP’s BSI testing, even 

though the Agency’s draft test procedure 

allows for this flexibility during testing. 

Since there is no vehicle present in the 

SV forward path, NHTSA does not 

expect there would to be any difference 

in how the SV’s speed is maintained 

during a given BSI test trial if manual/ 

robotic or cruise control is used. Cruise 

control is designed to regulate a 

vehicle’s longitudinal movement and 

therefore should not impact the lateral 

control functionality intrinsic to BSI. 

However, to ensure fairness across 

testing, it is most appropriate for NCAP 

to conduct testing utilizing only one 

method of speed control to ensure that 

the performance of one vehicle system 

(BSI) is not affected in any way by the 

performance of another system (cruise 

control). NHTSA is choosing to test with 

manual or robotic control in lieu of 

cruise control since consumers may 

sometimes opt not to use a cruise 

control feature, particularly on nonhighway roads. NHTSA notes that 55 

percent of fatal and 82 percent of 

injurious lane-change crashes, on 

average, occurred annually between 

2011 and 2015 on roadways that were 

not considered highways.331 332 The 

Agency will also not use LCA during 

NCAP’s BSI tests since not all vehicles 

are equipped with such features. 

As detailed later in the section, the 

Agency will nominally perform four 

unique tests for each of the three BSI 

test scenarios (i.e., with the POV on the 


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left and right sides of the vehicle and 

with the SV turn signal engaged and 

disabled). If the SV intervenes and 

meets the test procedure requirements 

during a trial run, testing will continue 

until all test conditions are assessed. If 

the SV does not provide an acceptable 

intervention during any trial run 

conducted for a given test condition, 

BSI testing will cease for the vehicle 

model. This test methodology is 

appropriate for BSI because it aligns 

well with that adopted for BSW and the 

other ADAS technologies to be included 

in NCAP. 

However, in a departure from other 

ADAS technologies included in this 

notice, NHTSA will assess BSW 

separately from its active technology 

counterpart (BSI) for NCAP. NCAP has 

not previously evaluated technologies 

associated with blind spot warning or 

intervention, but assessments for 

forward collision and lane departure 

warning technologies have been 

included in NCAP’s crash avoidance 

testing since model year 2011. Based on 

this, it is appropriate to allow 

manufacturers to receive NCAP credit 

for BSW systems while working toward 

improved BSI performance. 

Finally, in response to Auto 

Innovators’ concern regarding inclusion 

of BSI results in a rating, for this NCAP 

update, vehicles achieving no-contact 

results (and, in the case of false-positive 

testing, no intervention) and exhibiting 

no secondary departure, will receive a 

check mark on NHTSA’s website. 

Results will not be combined into a 

rating in the immediate future, but 

NHTSA may do so at a later date. 

5. Use of the Turn Signal for BSI 

NHTSA’s draft BSI procedure requires 

utilization of the left turn signal during 

BSI tests, with no instances where the 

turn signal is not enabled in the 

proposed procedure. NHTSA requested 

comments on whether this is 

appropriate, and if not, how the Agency 

could differentiate the operation of BSI 

from the heading adjustments resulting 

from an LKA intervention. NHTSA also 

asked whether the SV’s LKA system 

should be switched off during conduct 

of the Agency’s BSI evaluations. 

Summary of Comments 

Turn Signal Activation 

Several commenters stated that it is 

reasonable to perform BSI tests with the 

turn signal enabled. FCA, GM, Honda, 

Tesla, and Auto Innovators responded 

that BSI tests should be conducted only 

with the turn signal. FCA, Honda, Tesla, 

and Auto Innovators commented that 

drivers conduct lane changes with 

intent, so activation of the turn signal is 

appropriate. GM also noted that BSI is 

reliant on LKA functionality and that 

the use of the turn signal would 

distinguish BSI performance from LKA. 

Toyota, IDIADA, ASC, and ZF Group 

commented that testing both with and 

without turn signal use would be 

appropriate. Many of these commenters 

noted that real-world drivers may not 

signal intent to make a maneuver and 

that the technology should operate 

regardless of whether the turn signal is 

used. ASC stated that testing in this 

manner could ‘‘identify whether there is 

any difference in operation due to the 

turn signal status.’’ 

Some commenters, including Rivian, 

CAS, Aptiv, and one anonymous 

individual, suggested that turn signals 

should not be used during BSI testing. 

Rivian likened BSI to CIB, stating that 

‘‘BSI can be equated to collision 

imminent braking (CIB) in the manner 

that CIB is the elevated interventional 

stage following forward collision 

warning (FCW).’’ Rivian reasoned that 

turn signal activation should only affect 

warning behavior, not intervention 

behavior. CAS and an anonymous 

individual noted that, as previously 

mentioned, drivers may fail to signal 

intent, with CAS stating that ‘‘NHTSA 

tests should not be based on idealized 

good driving practices but should 

instead include plausible driving 

errors’’. Aptiv further stated that not 

engaging the turn signal is more 

representative of a real-world driving 

scenario. 

LKA Status if Turn Signal is Off 

The Agency also requested comments 

on whether LKA should be deactivated 

during BSI evaluations if the turn signal 

is not used in order to differentiate 

performance between LKA and BSI 

systems. DRI indicated that if the LKA 

system cannot be turned off the use of 

the turn signal should be required, 

stating otherwise it would be difficult to 

discern any performance difference. DRI 

stated it did not have an opinion on the 

matter if the LKA system could be 

turned off. Honda opined that LKA 

status would not ultimately be relevant 

as, even if LKA were allowed to remain 

on, BSI would ‘‘take over authority for 

intervention,’’ but noted that if LKA was 

disabled, ‘‘the BSI performance will 

operate more consistently as a BSI 

system.’’ 

Toyota, IDIADA, FCA, GM, BMW, and 

Tesla commented that they preferred the 

LKA system remain enabled while 

performing BSI tests. Toyota, IDIADA, 

and others also suggested NHTSA 

should focus on technology neutrality, 

meaning that the test requirements 

should not dictate the technologies 

needed to meet them. Toyota further 

stated that ‘‘in the real-world condition, 

both systems may be active and function 

in combination as part of the overall 

vehicle ADAS features.’’ Those in favor 

of keeping the LKA system enabled 

noted that BSI and LKA may be 

integrated systems that cannot be 

separated from one another. Toyota, 

BMW, and GM suggested that LKA is 

likely suppressed in the ‘‘turn signal 

on’’ condition for some current vehicles. 

Three respondents, Aptiv, Rivian, and 

one anonymous individual, supported 

the deactivation of LKA during BSI 

testing. Rivian asserted that consumers 

may turn off LKA due to personal 

preference and, therefore, BSI should be 

assessed independently. Rivian also 

stated that there will be some 

interaction between LKA and BSI but 

that ‘‘the OEM should be responsible for 

determining the detailed interactions 

and communicating their function and 

interaction to the customer.’’ Aptiv 

supported disabling LKA and/or ‘‘auto 

lane change features’’ for vehicles 

equipped with SAE Driving Automation 

Levels 2 and 3. 

ASC and ZF Group found value in 

evaluating BSI separately from LKA but 

supported a different approach to 

differentiate performance. Both groups 

mentioned that LKA may not always be 

active due to various circumstances. 

Because BSI is proximity-based and not 

dependent on lane markings, both 

groups suggested that the Agency could 

avoid activating LKA instead of 

disabling it by testing vehicles on ‘‘a 

roadway without lane markings to 

differentiate a BSI intervention from an 

LKS intervention.’’ Advocates also 

reasoned that BSI should operate 

independent of lane lines and 

recommended that the Agency 

determine protocols to test BSI without 

triggering LKA interventions and vice 

versa. 

Other commenters stated that more 

research and test development is 

necessary. CAS commented that the 

‘‘underlying logic’’ for LKA and BSI 

systems is different, so different tests are 

required. However, CAS noted logic 

differs between vehicle models, so the 

means to discriminate performance of 

each system may also be different. 

Advocates requested that NHTSA 

provide its ‘‘research and evaluation of 

vehicles with BSI and LKS systems to 

justify any decision regarding testing 

protocols.’’ 

Response to Comments and Agency 

Decisions 

NHTSA will conduct all three BSI test 

scenarios (i.e., the SV Lane Change with 


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333 87 FR 13461. 

Constant Headway scenario, the SV 

Lane Change with Closing Headway 

scenario, and the SV Lane Change with 

Constant Headway False Positive 

scenario) two times for each POV 

approach direction (left and right)— 

once with the turn signal engaged and 

once without use of the turn signal. 

Assessments will be performed with the 

vehicle’s LKA system ‘off’ if the LKA 

system can be disengaged and its LCA 

system ‘off’ if the vehicle is so 

equipped. 

The Agency agrees with commenters 

who stated that turn signal use during 

NCAP’s BSI test is appropriate; the 

related test scenarios represent 

situations where drivers intend to 

conduct a lane change. NHTSA also 

agrees with GM that use of the turn 

signal in the Agency’s BSI tests serves 

to distinguish BSI performance from 

that of LKA. NHTSA’s LKA tests are 

designed to represent unintentional lane 

departures, and as such, the turn signal 

is not engaged. However, as mentioned 

for BSW, there is merit to the assertion 

from other commenters that drivers 

often fail to outwardly signal intent to 

make a lane change by engaging their 

turn signal. Both use and non-use of the 

turn signal can represent intentional 

lane departure situations during realworld driving. By omitting the latter, the 

Agency would fail to capture a 

significant portion of use cases in the 

real world. Rivian’s point that turn 

signal activation may affect whether the 

vehicle warns the driver but not 

whether it intervenes once the driver 

begins to perform a lane change is also 

valid. Once the lane change maneuver 

has begun, the driver’s intent is known, 

regardless of whether the driver 

activated the turn signal indicator, and 

the vehicle’s BSI system should respond 

accordingly. Given this, the Agency 

would be remiss to only evaluate a BSI 

system’s ability to intervene in 

situations where the driver has utilized 

their turn signal. As several respondents 

suggested, NHTSA must also assess 

system functionality when the turn 

signal is not used prior to a lane change 

maneuver. 

NHTSA will perform all BSI 

assessments for a vehicle (i.e., both 

those conducted with the turn signal 

activated and those conducted without) 

with the LKA system ‘off’ if the LKA 

system can be disengaged. LKA systems 

provide brief heading corrections 

needed to bring a vehicle away from a 

lane line after it has been crossed or if 

a crossing has been deemed imminent. 

Although the Agency recognizes that 

several respondents recommended that 

the LKA system remain enabled while 

performing BSI tests to promote 

technology neutrality, NHTSA asserts 

that setting the LKA system to ‘off’ is 

more appropriate. A vehicle’s LKA 

system is not guaranteed to be ‘on’ 

during real-world driving. While it is 

true that BSI and LKA systems may both 

be active and function in combination 

during real-world driving as Toyota 

asserted, it is also possible that 

consumers may turn off LKA due to 

personal preference, as Rivian 

contended. Further, as noted in the 

March 2022 RFC, NHTSA is aware of 

studies which suggest that drivers 

frequently disable lane departure 

technologies.333 Accordingly, assessing 

BSI functionality independent of LKA 

functionality during NCAP’s BSI tests 

seems appropriate. 

Although DRI recommended that turn 

signal use should be required for any 

tests conducted for vehicles in which 

the LKA system cannot be turned off to 

discern performance differences 

between a vehicle’s BSI and LKA 

systems, it is still appropriate to perform 

assessments both with and without turn 

signal engagement in such instances. As 

mentioned, not all drivers utilize the 

turn signal indicator when changing 

lanes. As Honda opined, BSI should 

resume intervention authority even if 

the LKA system remains ‘on’ for testing. 

If a vehicle’s LKA system were to affect 

BSI performance for fully-integrated 

LKA and BSI systems, any influence 

should be representative of real-world 

driving circumstances. As such, it is 

appropriate to still include an 

evaluation requiring that the turn signal 

not be activated for those vehicles 

where the LKA system cannot be turned 

‘off.’ 

NHTSA will not test vehicles on a 

roadway without lane markings to 

differentiate BSI and LKA interventions 

without deactivating LKA, as suggested 

by several commenters. Since most 

multiple lane roads conducive to lane 

changes on which vehicles will be 

travelling at the speeds to be assessed 

will have lane lines, conducting BSI 

tests on roadways devoid of lane 

markings would not be representative of 

real-world driving conditions. Further, 

while lane markings may not influence 

BSI performance for vehicles with LKA 

systems that can be switched off, the 

Agency reasons a lack of lane markings 

may affect both LKA and BSI system 

functionality (and thus BSI 

performance) for those vehicles with 

fully integrated BSI and LKA systems 

where LKA cannot be deactivated for 

BSI testing. This assumption is 

bolstered by GM’s assertion that BSI is 

reliant on LKA functionality. 

Finally, as previously mentioned, the 

Agency will set a vehicle’s LCA system, 

which serves to continuously provide 

steering inputs needed to keep a vehicle 

centered in its lane of travel, to ‘off’ (if 

equipped) for all BSI tests. 

6. User-Configurable Settings for BSW 

and BSI Tests 

For NHTSA’s BSW and BSI testing, 

the Agency will set the timing for the 

warning in BSW systems and 

intervention in BSI systems to the 

middle (or next latest) setting (if 

adjustable) during its BSW/BSI 

evaluations, similar to that previously 

shown in Figure 2 for FCW evaluations. 

For BSW and BSI systems having only 

two settings, the Agency will select the 

later of the two settings and this test 

setting will meet NHTSA’s middle (or 

next latest) BSW/BSI setting 

requirement. These system setting 

configurations align with Euro NCAP’s 

LSS test protocol. 

All BSW and BSI tests will also be 

conducted with LKA and cruise control 

(i.e., conventional or adaptive cruise 

control, or ACC) ‘off’ if such systems 

can be disengaged. Lane centering 

functions will also be set to ‘Off’ for all 

BSW and BSI tests in alignment with 

Euro NCAP’s LSS test protocol. 

7. BSI False Positive Testing 

NHTSA proposed including a false 

positive test (SV Lane Change with 

Constant Headway, False Positive 

Assessment Test) in its BSI test 

procedure to evaluate the propensity of 

the system to inappropriately activate in 

a situation that does not pose a crash 

risk to those in the SV. 

Summary of Comments 

Commenters expressed mixed 

opinions for this proposed test scenario. 

Some, including TRC, CAS, Advocates, 

ZF Group, Vayyar, Intel, Rivian, and one 

anonymous individual, commented that 

a false positive test scenario is a 

valuable testing inclusion. Many 

commenters, including CAS, Advocates, 

ZF Group, Vayyar, Rivian, and CR, 

conveyed that false positive activations 

could cause customer dissatisfaction, 

leading to customers ignoring or 

deactivating the technology. TRC 

commented that to maximize the benefit 

of a technology, NHTSA must encourage 

maximum consumer confidence and 

use. Advocates mentioned this is 

particularly important for active 

technologies in which the driver cannot 

ignore a false positive activation. CAS 

and Vayyar noted that inappropriate 

activation may cause undesirable driver 

reactions, leading to potentially 

dangerous driving behavior. 


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Other commenters stated that the false 

positive testing scenario is not 

appropriate or necessary for NCAP. 

Auto Innovators and Toyota stated that 

false positive activations are difficult to 

reproduce because of situational 

complexity and suggested that a limited 

number of test runs cannot determine 

the overall robustness of the system. 

FCA did not oppose the inclusion of a 

false positive test scenario but reasoned 

that it may be difficult to determine a 

concise test methodology. Toyota and 

others stated that manufacturers may 

begin designing their systems to pass 

tests instead of performing acceptably in 

real-world conditions. 

As discussed in the AEB and PAEB 

sections, manufacturers commented that 

they are strongly motivated to design 

robust systems that do not falsely 

activate because they have a vested 

interest in maximizing consumer 

satisfaction. FCA responded that 

manufacturers will discover excessive 

false-positive activations through 

customer complaints and quality 

metrics. Likewise, GM noted that, due to 

the myriad of situations that may trigger 

a nuisance activation, the automaker 

would find these customer quality 

metrics and field data reports to be more 

useful. Rivian and BMW shared that 

manufacturers often already conduct inhouse false positive testing to ensure 

customer acceptance, and Toyota stated 

that manufacturers must take the 

consumer’s satisfaction into account 

when balancing true positive cases with 

true negative and false positive cases. 

Honda and Auto Innovators noted that 

BSW systems have high consumer 

satisfaction without the need for a false 

positive test, and both groups stated 

they expect that BSI systems will also be 

accepted similarly. 

BMW indicated that because of the 

work already completed on eliminating 

false positives by manufacturers, there 

would be little benefit to adding a false 

positive scenario to NCAP’s testing 

regimen. The automaker further stated 

that performing a small number of tests 

to mitigate false activations would not 

adequately address the variety of 

driving conditions that a driver may 

experience and would not be 

commensurate with the amount of test 

effort needed. Bosch noted that 

specialized infrastructure and 

equipment may be needed to conduct 

false positive test scenario runs, adding 

unnecessary test burden and 

complexity. 

Tesla and Auto Innovators mentioned 

that the reduction of false positives may 

also come at the cost of increased false 

negatives, and HATCI suggested that 

false positive testing could lead to 

unintended consequences that may 

impact future technologies. HATCI 

recommended that NHTSA focus on test 

scenarios that represent safety needs 

from the field, particularly ones that 

address fatal and injurious crashes. 

Tesla commented that the greatest safety 

benefits will be realized when false 

negatives are minimized, adding that 

vehicle manufacturers may add other 

countermeasures to further mitigate 

false positives. 

In relation to the false positive test 

procedure itself, DRI proposed that false 

positive scenarios do not require the full 

set of test runs specified for baseline 

tests and stated that no more than three 

would be necessary. Additionally, 

Vayyar noted the importance of 

including typical surroundings and 

static objects like fences, parked cars, 

trees, etc. ASC echoed this sentiment, 

commenting that NHTSA should 

consider what objects or scenarios may 

trigger false activations when 

developing and selecting test 

procedures for NCAP. As an example, 

ASC stated that BSI systems may falsely 

activate in response to oncoming traffic 

in the adjacent lane or stationary 

objects. 

Response to Comments and Agency 

Decisions 

The Agency is retaining the SV Lane 

Change with Constant Headway, False 

Positive Assessment test scenario 

currently included in its BSI test 

procedure. As mentioned, the objective 

of this test scenario is to assess whether 

the BSI system detects and responds to 

a non-threatening POV during a single 

lane change. The Agency’s decision is 

consistent with the decision made by 

the Agency for AEB and aligns with the 

comments received by many, though not 

all, respondents. 

In response to the Agency’s March 

2022 RFC notice, vehicle manufacturers 

reiterated similar comments to those 

submitted in response to the Agency’s 

false positive AEB tests. Most notably, 

they maintained that false positive tests 

in NCAP should be unnecessary because 

automakers have an inherent interest in 

designing robust systems and limiting 

false activations to maintain high 

customer satisfaction. Several 

manufacturers asserted that excessive 

false activations would be realized 

through quality metrics and/or customer 

complaints or through internal testing. 

However, if a manufacturer’s efforts 

were sufficient to eliminate false 

positive activations, such incidents 

would not be observed by 

manufacturers in field data reports. 

Further, while BMW contended there 

would be little benefit to adding a false 

positive scenario to the matrix because 

of manufacturer efforts to date to 

eliminate false positive activations for 

blind spot technologies, NHTSA 

questions this rationale. Only 38 percent 

of model year 2024 vehicles are 

currently equipped with BSI 

technology. As such, acceptable false 

positive rates for yet-to-be-designed BSI 

systems for the majority of the vehicle 

fleet cannot be intrinsically assumed. 

NHTSA also rejects Toyota’s assertion 

that incorporating a false positive test 

for BSI would encourage manufacturers 

to design systems solely to pass the 

Agency’s tests, rather than to perform 

well during real-world driving, as acting 

in such a manner would seemingly 

conflict with automakers’ assertions of 

performing due diligence and assuring 

customer satisfaction. Further, the test 

conditions for the SV Lane Change with 

Constant Headway, False Positive 

Assessment test are not obscure. As 

such, NHTSA does not foresee that a 

vehicle will achieve good BSI false 

positive assessment performance as a 

direct result of compromised operation 

in other real-world driving situations. 

Based on these considerations, adopting 

a false positive test for NCAP’s BSI test 

matrix is appropriate and can be 

incorporated without an associated 

increase in false negatives or other 

unintended consequences, as expressed 

by some commenters. 

The Agency also agrees with those 

commenters who supported the 

inclusion of a false positive BSI test and 

suggested that NHTSA should 

discourage false positive activations, 

encourage system use, and ensure 

consumer confidence in blind spot 

technology. Any false positive 

activation may cause drivers to respond 

with irresponsible driving behavior, as 

CAS and Vayyar suggested, or cause 

general customer dissatisfaction, 

potentially leading to deactivation of the 

technology. Advocates’ assertion that 

maintaining a high level of customer 

satisfaction is especially important for 

active technologies since a system’s 

intervention cannot simply be ignored 

by the driver is valid. Though Honda 

and Auto Innovators suggested that, 

since BSW systems currently have a 

high rate of customer satisfaction 

without an associated false positive test, 

so too should BSI systems, the Agency 

does not agree with this deduction. 

Rather, adopting a false positive test for 

NCAP’s BSI test matrix will help ensure 

sensor robustness and thereby maintain 

or improve overall consumer sentiment 

pertaining to blind spot technology. 

The Agency maintains this position 

while also acknowledging that the 

proposed false positive test is neither 


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334European New Car Assessment Programme 

(Euro NCAP) (December 2023), Test Protocol—Lane 

Support Systems, Version 4.3. See section 5. 335 ISO 19206–3:2021. 

comprehensive enough nor adequate to 

eliminate susceptibility to all false 

activations, as BMW and GM asserted. 

NHTSA acknowledges that a myriad of 

situations may trigger a false positive 

system response during real-world 

driving. It is also true, as Toyota and 

Auto Innovators contended, that one 

test may not sufficiently gauge overall 

system robustness. However, NHTSA 

reasons that its SV Lane Change with 

Constant Headway, False Positive 

Assessment test serves to provide a 

baseline for BSI system functionality 

and establish a minimum expected 

performance level. If the test provides 

even limited coverage of real-world lane 

change/merge conditions, it will afford 

additional safety, and is thus 

advantageous to include for NCAP’s BSI 

evaluations. 

Several commenters suggested that 

false positive tests are inherently 

difficult to conduct (Auto Innovators 

and Toyota) or require specialized 

infrastructure and equipment (Bosch). 

However, this is not the case for the 

Agency’s SV Lane Change with Constant 

Headway, False Positive Assessment 

test. This test, which requires that the 

SV perform a single lane change into an 

adjacent lane while the POV is driven 

straight, is relatively easy to conduct 

and has been performed successfully as 

part of NHTSA’s research test program. 

It imposes no additional complexity or 

test burden compared to the other BSI 

tests included in the Agency’s test 

protocol, other than the additional three 

baseline runs necessary for each test 

condition that must be conducted to 

assess BSI system performance. NHTSA 

recognizes that DRI suggested it was 

necessary to perform only three baseline 

runs for the false positive test scenario 

(i.e., three baseline runs for each test 

condition), and the Agency agrees, since 

the Agency’s research testing has shown 

three baseline runs to be sufficient and 

this should keep test burden to a 

minimum. 

At this time, NHTSA will not require 

placement of additional static objects 

within the test environment for its BSI 

assessments, as Vayyar and ASC 

requested. As previously mentioned, the 

Agency’s false positive BSI test is 

intended to serve to judge a level of 

minimum acceptable performance. It is 

not expected to address the numerous 

potential lane change/merge driving 

situations that may invoke a false 

positive intervention. Additionally, as 

BSI will be a newly adopted technology 

for NCAP, it is currently more important 

to encourage technology adoption across 

a larger segment of the vehicle fleet 

rather than the adoption of overly 

burdensome requirements. The Agency 

has also not conducted research to 

assess the impact of such objects on 

system performance, and it would 

therefore be premature to incorporate 

these items in test scenarios adopted for 

this NCAP upgrade. 

Although static objects and oncoming 

vehicles will not be part of the Agency’s 

initial BSI assessments, NHTSA expects 

that vehicle manufacturers should 

design BSI systems to address the 

potential for false activations in all 

possible real-world situations so that 

vehicles do not pose an unreasonable 

risk to safety. Given the comments 

received, this expectation aligns with 

steps already being taken by automakers 

to ensure customer satisfaction. Similar 

to the plan discussed for AEB, NHTSA 

will continue to monitor customer 

complaints to look for reports of 

frequent false activations for BSI 

systems as part of its defects 

identification and investigation process. 

The Agency also has the authority to 

investigate whether vehicles 

experiencing excessive false positive 

activations have a safety-related defect 

since they may pose an unreasonable 

risk to safety. NHTSA will continue to 

handle such cases appropriately as they 

arise. The Agency may also consider 

adding other false positive tests to 

NCAP in the future to capture 

additional driving situations if realworld data suggests a safety need exists. 

8. Use of the ABD GVT Revision G for 

BSI Testing 

A real vehicle is currently utilized in 

the Agency’s BSW test procedure. 

However, in the March 2022 RFC, 

NHTSA detailed its intent to use the 

[ABD] GVT Revision G in its BSI test 

procedure as the vehicle test device. As 

previously discussed in the AEB 

section, the ABD GVT Revision G 

vehicle test device includes minor 

changes to its shape and radar 

characteristics to more closely 

approximate an actual vehicle. Its use in 

NCAP’s BSI test would further promote 

global harmonization since the GVT is 

used in Euro NCAP’s Lane Support 

Systems testing protocol.334 NHTSA 

used the ABD GVT Revision G in its 

pilot testing series. 

Summary of Comments 

Most commenters remarking on this 

topic agreed the [ABD] GVT Revision G 

is the most appropriate strikeable 

vehicle test device for use in BSI testing. 

MEMA, FCA, Bosch, Honda, Auto 

Innovators, Toyota, ASC, ZF Group, 

Rivian, BMW, HATCI, Tesla, Intel, and 

GM were all in favor. The use of a 

standardized vehicle test device was a 

motivating factor for nearly all 

commenters who indicated approval 

(Auto Innovators, Toyota, ASC, ZF 

Group, BMW, HATCI, Tesla, and Intel). 

Auto Innovators also commented that 

the use of the [ABD] GVT Revision G for 

BSI testing would reduce test burden for 

manufacturers and laboratories since the 

same vehicle test device could be used 

for CIB and DBS. Bosch noted the [ABD] 

GVT Revision G’s improved side 

strength and radar characteristics. 

However, GM preferred the ‘‘most 

representative test target that can safely 

be used in all intended test scenarios,’’ 

meaning that if there is low risk of POVto-SV contact, a real vehicle would be 

more desirable. For more aggressive BSI 

scenarios, GM agreed that the use of the 

[ABD] GVT Revision G is appropriate. 

Advocates remarked that NHTSA 

should justify any aspect of the test 

procedures, including the strikeable 

vehicle test device used, through 

presentation of testing and data 

analyses. Bosch also requested that 

NHTSA refer to a standard 335 rather 

than a specific product in its test 

procedures to give more flexibility to 

those implementing tests. Should there 

be any changes to the ABD GVT 

Revision G, HATCI requested that the 

Agency provide a chance to review the 

changes with sufficient lead time to 

understand the impact that such 

changes may have on its product design. 

With respect to logistical concerns, 

TRC questioned whether NHTSA would 

find it acceptable to retrofit an [ABD] 

GVT Revision F soft car (or other) with 

a kit to bring it in line with Revision G 

specifications. It also noted that minor 

impacts with the vehicle test device 

may interfere with vehicle kinematics at 

the higher test speeds specified in the 

proposed procedure. For this reason, the 

laboratory asked whether the Agency 

would require contact to determine 

performance or if a tight tolerance for no 

contact may be used instead, citing a 

desire to reduce test burden. 

Response to Comments and Agency 

Decisions 

Based on the comments received, 

NHTSA has decided to use the ABD 

Revision G GVT for NCAP’s BSI tests at 

this time. Adopting this test device for 

NCAP’s BSI tests should minimize 

burden for manufacturers since the 

same test device will be prescribed in 

the Agency’s AEB test protocol and is 

approved for use in Euro NCAP’s LSS 


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336https://www.euroncap.com/en/for-engineers/ 

supporting-information/technical-bulletins/. See 

Appendices I & II. 

337https://www.iso.org/standard/70133.html. 

May 2021. 

and AEB test protocol evaluations.336 In 

addition, the ABD GVT Revision G was 

found to be robust and durable in the 

Agency’s most recent BSI research tests. 

Further, ABD has indicated this test 

device complies with ISO 19206– 

3:2021, ‘‘Road vehicles—Test devices 

for target vehicles, vulnerable road users 

and other objects, for assessment of 

active safety functions—Part 3: 

Requirements for passenger vehicle 3D 

targets’’ 337 with respect to the 

specifications outlined for radar cross 

section, reflectivity, color, and physical 

dimensions. Therefore, the Agency 

considers it an acceptable surrogate of a 

real vehicle and appropriate for use in 

NCAP’s BSI assessments. 

Specifying a standardized vehicle test 

device is appropriate, as doing so 

should promote fairness and ensure 

repeatability and reproducibility of test 

results. That being said, the Agency also 

recognizes, as Bosch mentioned, that 

stipulating a standard the BSI vehicle 

test device must comply with instead of 

designating a specific device for use will 

afford more flexibility to those 

conducting BSI tests. While there are 

benefits to such an approach, NHTSA 

has not conducted thorough evaluations 

of alternative test devices that also meet 

the ISO specifications, such as the 4a 

GVT, to ensure they invoke equivalent 

vehicle/system performance as the ABD 

GVT Revision G in the Agency’s BSI 

tests. Therefore, at this time, the Agency 

is specifying use of the ABD GVT 

Revision G in NCAP’s BSI tests to 

mitigate variability between the 

Agency’s official test results and those 

submitted by the vehicle manufacturer. 

The Agency notes that while it allows 

use of a real vehicle during its BSW 

testing, this is not an appropriate 

approach for its BSI testing. This is 

because for NHTSA’s BSI tests (with the 

exception of the false positive test 

scenario), the SV initiates a manual lane 

change into the POV’s travel lane. 

Because of this lane change maneuver, 

contact between the SV and POV is 

possible. On the other hand, SV 

movement in NHTSA’s BSW tests is 

confined to a pass-by maneuver, where 

both the SV and POV maintain their 

position within their respective lanes, or 

a converge/diverge maneuver, where the 

POV performs a lane change into a lane 

that is adjacent to the SV but not in the 

same lane as the SV. Consequently, the 

ABD GVT Revision G, not a real vehicle, 

is appropriate for NCAP’s BSI testing so 

tests can be conducted safely. While the 

Agency will permit use of a real vehicle 

in NCAP’s BSW tests, it is also 

amending the test procedure to allow 

use of the ABD GVT Revision G in those 

test scenarios. Further, since the BSI 

false positive test should not result in 

contact, the Agency’s test procedure 

will permit use of a real vehicle for that 

test scenario. 

Along these lines, NHTSA will not 

alter the no contact evaluation criterion 

currently included in the Agency’s BSI 

test procedure to permit a tolerance, as 

TRC requested. Contact was observed 

during numerous trials conducted as 

part of the Agency’s BSI research testing 

and vehicle kinematics post-contact did 

not generate concern for the safety of 

laboratory personnel or create 

additional test burden. 

Although NHTSA will use the ABD 

Revision G GVT in its official BSI 

testing and will not accept manufacturer 

test data for BSI assessments performed 

utilizing alternative test devices at this 

time, manufacturers may choose to 

utilize ABD GVT Revision F, as TRC 

requested, when performing tests for 

NCAP data submission, if it is retrofitted 

with a kit to ensure it meets the 

specifications for Revision G. Such 

adaptations are necessary because ABD 

GVT Revision G includes changes to the 

front and sides when compared with 

Revision F, specifically to permit 

improved side strength and radar 

characteristics. Any revision of the ABD 

GVT utilized for BSI testing, whether 

Revision G or Revision F that has been 

retrofitted to be equivalent to Revision 

G, must also meet all specifications and 

requirements outlined herein as well as 

those prescribed in NHTSA’s BSI test 

procedure. 

With regards to HATCI’s concerns 

pertaining to version control of the 

vehicle test device, the Agency will be 

as transparent as possible about any 

potential changes to test equipment 

used for its BSI performance evaluations 

in the future. 

Vehicle Test Device Specifications 

Even though it is not necessary to 

prescribe all specifications for the ABD 

GVT Revision G for NCAP testing, since 

compliance with the ISO standard 

should be inherent, the Agency is 

nonetheless referencing ISO 19206– 

3:2021 in NCAP’s BSI test procedures, 

as it did for NCAP’s AEB tests. This 

should ensure any device utilized for 

Agency testing complies with the 

standard’s specifications. 

9. Number of Trials and Pass Rate 

As with the other ADAS technologies 

proposed, the Agency’s proposed BSW 

and BSI test procedures included 

multiple trial runs for each given test 

scenario. The proposed BSW test 

procedure required seven repeated trials 

for each test condition (i.e., left and 

right POV approach direction) assessed 

for a scenario (14 tests overall for 

Straight Lane Converge and Diverge and 

56 tests overall for Straight Lane Passby). The number of proposed trials for 

the BSI procedure depended upon the 

test scenario to be performed. Seven 

repeated trials were specified for the SV 

Lane Change with Constant Headway 

test and the SV Lane Change with 

Closing Headway test, while three 

repeated trials were prescribed for the 

SV Lane Change with Constant 

Headway, False Positive Assessment 

Evaluation test. NHTSA requested 

comments on the appropriate number of 

trials required for each adopted test 

condition and the appropriate pass rate 

for BSW and BSI tests. The Agency 

proposed that a vehicle would have to 

pass five out of seven trials for a given 

BSW test condition to receive credit for 

the technology; however, no pass rate 

was proposed for BSI systems. 

Summary of Comments 

Number of Trials 

Several commenters provided input 

suggesting the number of trials for BSW 

could be reduced from what NHTSA 

proposed. TRC, GM, IDIADA, Rivian, 

Auto Innovators, Tesla, and Bosch 

opined that fewer than seven trials are 

needed. Those in favor of trial run 

reduction mentioned there is 

consistency in vehicle alert times (TRC) 

and limited variance in test results. 

TRC, GM, and Rivian were in favor of 

reducing the number of trial runs to 

five, while Bosch and Tesla 

recommended reducing the number to 

three trials. Tesla stated that three trials 

are needed for BSW because it is a 

warning system only and does not 

intervene, with the driver maintaining 

control of the vehicle. IDIADA 

recommended reducing to just one trial 

run, citing relevant experience in LKA 

and AEB testing. However, it also stated 

that the BSW pass-by test is simple and 

subsequent trials can be performed 

easily if desired. Toyota and Auto 

Innovators suggested a reduction to 

either three or five trials to alleviate test 

burden. Like others, Intel suggested that 

NHTSA seek to reduce unnecessary test 

burden, but the company did not offer 

a specific number of trial runs that 

should be included. 

TRC made the recommendation to 

perform five trial runs for both BSW and 

BSI. The laboratory asserted that the 

battery life of the GVT robotic platform 


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can become problematic, and thus, a 

decrease in the number of test runs 

could preserve the platform’s battery 

and eliminate some invalid runs. Rivian 

also recommended that NHTSA reduce 

the procedural requirement for BSI to 

five trial runs. On the other hand, Tesla 

recommended running seven BSI trials 

per test condition. While the automaker 

expressed support for reducing the 

number of BSW trial runs, it did not 

support a reduction for BSI tests 

because the system controls the vehicle 

on the driver’s behalf. Tesla reasoned 

that NHTSA should more rigorously 

evaluate any vehicle interventions not 

initiated by the driver. 

Other commenters stated that seven 

trial runs are appropriate for BSW. 

Honda, FCA, ASC, BMW, and ZF Group 

supported NHTSA’s proposal for seven 

trials. The main reason cited for keeping 

the trial run count the same was 

maintaining consistency with existing 

test procedures. It should be noted that, 

while GM and Auto Innovators were in 

favor of reducing the number of trial 

runs per condition, both groups were 

also not opposed to maintaining seven 

trial runs. GM mentioned maintaining 

consistency amongst different test types 

and asked the Agency to consider that 

additional trial runs in the same test 

scenario are not as labor-intensive as 

changing the test setup to a different test 

scenario. GM therefore requested 

NHTSA optimize the number of test 

scenarios rather than focus on the 

number of test runs. 

Advocates and CAS opined there 

must be additional evidence provided to 

determine the appropriate number of 

test runs. Advocates stated that NHTSA 

should provide evidence that the 

number of trials selected will ensure 

that vehicles identified with the 

technology will operate as intended for 

the life of the vehicle. Similar to its 

requests for the other technologies 

NHTSA proposed for adoption in 

NCAP, CAS requested that the Agency 

use a statistical analysis to determine an 

appropriate number of trials to ensure 

system robustness. 

Pass Rate 

Many commenters suggesting that 

seven BSW trials should be conducted 

held the view that five of seven tests 

should be required to pass to gain BSW 

system credit. Honda, GM, FCA, ASC, 

BMW, and ZF Group expressed that 

requiring five of seven tests to pass is 

reasonable, offers credit to systems 

which will effectively mitigate realworld crashes, and maintains 

consistency with existing ADAS test 

procedures. Although Auto Innovators 

expressed a preference for fewer trial 

runs per condition, should NHTSA 

continue with seven runs, the group 

recommended the Agency require five 

of seven runs to pass. Auto Innovators 

opined that if the first five runs pass, 

then the vehicle should be considered 

as passing and testing should be 

discontinued to reduce unnecessary test 

runs. 

Commenters recommending five trials 

often suggested that three of five should 

pass (Toyota, GM, and Auto Innovators). 

For those recommending three trials, 

most often commenters requested that 

two of the three trial runs pass. Toyota 

noted that one failed trial should be 

permitted to prevent a vehicle from 

being misclassified because of a one-off 

occurrence. The automaker stated that 

this follows other crash avoidance 

NCAP test methodology. Some 

commenters stated NHTSA should not 

permit any failed runs. However, 

IDIADA stated one test per condition 

should be sufficient, and vehicles 

should be expected to pass since test 

data does not show wide variation. 

Rivian and Tesla commented that 

pass rate should depend on the nature 

of the system evaluated, with both 

automakers stating that systems that 

deliver information (i.e., BSW) should 

be expected to pass 100 percent of the 

tests conducted. Both also asserted that 

systems which intervene to control the 

vehicle movement (i.e., BSI) should 

have a pass rate based on the nature of 

technology. Rivian stated that NHTSA 

should ‘‘take into account external and 

internal variables’’ and determine an 

appropriate pass rate based on this fact. 

Rivian stated it did not approve of 

binary pass/fail criteria for BSI but did 

not provide a suggested pass rate. Tesla 

recommended that five out of seven BSI 

trials per condition pass. 

Like the feedback received on the 

number of trials mentioned in the 

previous section, Advocates and CAS 

suggested that pass rates should be 

based on additional information and 

evidence. 

Response to Comments and Agency 

Decisions 

Number of Trials for BSW 

The Agency has determined that it 

will conduct one trial per test condition 

to ensure BSW system performance 

affords the consistency that consumers 

expect and safety demands. This 

finalized testing methodology is akin to 

that of AEB and PAEB testing. 

NHTSA does not agree with Tesla’s 

assertion that warning systems do not 

require the same level of rigor when 

they are assessed for NCAP. To maintain 

the credibility of the consumer 

information provided to the public, all 

ADAS technologies, whether warningbased or active safety features, should 

be proven reliable in the test conditions 

assessed before they are given credit for 

passing NCAP’s testing. NHTSA 

maintains, as it has done elsewhere in 

this notice, that the best way to ensure 

system reliability is not to perform 

repeated test trials. Repeated trials 

inherently permit a certain threshold of 

failures, and failures of any number are 

unacceptable under the limited, ideal 

test conditions to be assessed. As such, 

the Agency will perform a single trial 

for each test condition to assess BSW 

system performance. This decision 

aligns with assertions from those 

commenters who suggested that fewer 

BSW trials could be conducted than 

were proposed initially and maintains 

congruity amongst NCAP’s ADAS 

testing protocols, as multiple 

commenters requested. 

For the Straight Lane Converge and 

Diverge test scenario, NHTSA will 

perform one trial for each test condition 

(i.e., POV approach directions of right 

and left, each with turn signals enabled 

and disabled), resulting in four Straight 

Lane Converge and Diverge test trials 

total. For its BSW Straight Lane Pass-by 

testing, NHTSA will conduct one trial 

per each speed differential, POV 

approach side, and turn signal status 

combination for a total of 16 Straight 

Lane Pass-by trials per vehicle model 

assessed. Despite GM’s concern that 

changing the test setup is more difficult 

than simply running multiple trials for 

one scenario, this testing methodology 

should balance test burden with the 

Agency’s need to thoroughly evaluate 

BSW system performance. It should also 

limit damage to the test vehicle, vehicle 

test device, and equipment, and best 

ensure the safety of laboratory 

personnel. 

Considering all BSW testing adopted 

in this notice, each vehicle model 

assessed for BSW system performance 

will undergo 20 trials total, a significant 

reduction from the 70 initially proposed 

by NHTSA. This reduction in the 

number of trials should address 

Toyota’s concern regarding timely 

release of information to consumers. 

Number of Trials for BSI 

In the interest of test consistency, 

reduced testing burden, and ensuring 

system reliability, NHTSA will also 

apply the same one-trial test 

methodology to all three BSI assessment 

scenarios for NCAP: (1) SV Lane Change 

with Constant Headway, (2) SV Lane 

Change with Closing Headway, and (3) 

SV Lane Change with Constant 

Headway, False Positive Assessment. 


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Although Tesla suggested that 

NHTSA conduct seven trials for each 

BSI scenario because the vehicle 

intervenes on the driver’s behalf, test 

burden and logistical considerations are 

also factors that must be considered. 

With one trial required for each 

assessment condition (i.e., POV 

approach directions of right and left, 

each with turn signals enabled and 

disabled), a vehicle model will undergo 

12 trials for BSI testing overall. Given 

TRC’s concern that the GVT’s robotic 

platform has a limited battery life, 

which may serve to reduce testing 

efficiency and delay the release of 

information to the public, NHTSA does 

not wish to impart additional burden 

and delay for what it concludes to be 

limited benefit. In addition, since other 

ADAS technologies will no longer 

undergo seven trials, NHTSA reasons 

that a reduction in trials for BSI testing 

will best maintain consistency with 

other test procedures, a request 

expressed by several commenters. 

Proceeding with one trial per test 

condition will also best ensure 

performance consistency and safety 

benefits. 

Pass Rate 

The pass rate for all adopted BSW and 

BSI testing (i.e., 20 required tests to 

obtain credit for BSW and 12 required 

tests to obtain credit for BSI) will be 100 

percent. No test failures will be 

permitted during any of the BSW or BSI 

trials conducted for NCAP. 

NHTSA acknowledges that some 

commenters suggested BSW and BSI test 

pass rates should be treated differently 

because one is a warning technology 

only and the other is active. However, 

NHTSA disagrees with this assessment. 

As mentioned previously, the Agency 

reasons its assessment of performance 

should be handled with the same 

stringency whether a technology is an 

active technology or simply meant to 

provide information to the consumer. 

Tests that NHTSA is adopting for 

BSW and BSI testing are shown in 

Tables 23 and 24. 

TABLE 23—BLIND SPOT WARNING (BSW) ADOPTED TEST CONDITIONS

Test scenario SV speed 

(kph (mph)) 

POV speed 

(kph (mph)) 

POV direction 

of approach Turn signal 

Straight Lane Converge and Diverge ............................................................. 72.4 (45) 72.4 (45) Right .............. Enabled. 

Disabled. 

Left ................. Enabled. 

Disabled. 

Straight Lane Pass-by ..................................................................................... 72.4 (45) 80.5 (50) Right .............. Enabled. 

Disabled. 

Left ................. Enabled. 

Disabled. 

88.5 (55) Right .............. Enabled. 

Disabled. 

Left ................. Enabled. 

Disabled. 

96.6 (60) Right .............. Enabled. 

Disabled. 

Left ................. Enabled. 

Disabled. 

104.6 (65) Right .............. Enabled. 

Disabled. 

Left ................. Enabled. 

Disabled. 

TABLE 24—BLIND SPOT INTERVENTION (BSI) ADOPTED TEST CONDITIONS

Test scenario SV speed 

(kph (mph)) 

POV speed 

(kph (mph)) 

Lane change 

direction Turn signal 

SV Lane Change with Constant Headway ..................................................... 72.4 (45) 72.4 (45) Left ................. Enabled. 

Disabled. 

Right .............. Enabled. 

Disabled. 

SV Lane Change with Closing Headway ........................................................ 72.4 (45) 80.5 (50) Left ................. Enabled. 

Disabled. 

Right .............. Enabled. 

Disabled. 

SV Lane Change with Constant Headway, False Positive Assessment ........ 72.4 (45) 72.4 (45) Left ................. Enabled. 

Disabled. 

Right .............. Enabled. 

Disabled. 

10. Test Procedure Refinements 

Several commenters provided 

suggestions for specific test procedure 

refinements in response to the March 

2022 RFC notice. The Agency provides 

responses to these comments in the 

following section. 

NHTSA also published and requested 

comment on draft BSW and BSI test 

procedures in November 2019. The 

Agency received feedback from the 

public at that time, some of which was 

referenced again in comments to the 

March 2022 RFC notice. Updated BSW 

and BSI test procedures reflecting the 

Agency’s response to the comments 

received will be published separately in 

conjunction with this notice in the 

related docket. 


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338See https://safety.fhwa.dot.gov/geometric/ 

pubs/mitigationstrategies/chapter3/3_

lanewidth.cfm. 

Summary of Comments 

Harmonization was a common 

underlying theme in the comments 

received to the Agency’s March 2022 

RFC notice. Aptiv encouraged NHTSA 

to align its blind spot test procedures 

with the BSW and BSI content within 

Euro NCAP’s Lane Support System 

protocol to the greatest extent possible, 

whereas Bosch and Intel supported 

harmonization of NHTSA’s BSW 

procedure with ISO 17387:2008, 

Intelligent transport systems—Lane 

change decision aid systems (LCDAS)— 

Performance requirements and test 

procedures. Bosch asserted that 

adopting the ISO standard would lessen 

testing complexity and burden on 

manufacturers, while still offering a 

system to evaluate system performance 

and robustness. For BSI assessments, 

Auto Innovators and Bosch urged the 

Agency to harmonize its test procedures 

with ISO 19638:2018. Both Auto 

Innovators and GM, in addition to 

Aptiv, noted that the lane widths 

specified (3.7 to 4.3 m, or 12 to 14 ft.) 

do not align with U.S. lane width 

standards and suggested that the Agency 

consider aligning the lane width 

specifications to Euro NCAP’s: 3.5 to 3.7 

m (11.5 to 12 ft.). 

Other comments focused on specific 

procedural changes, with Aptiv raising 

concerns regarding the onset and 

termination headways specified in the 

BSW test procedure. The company 

recommended that the alert engagement 

requirement be defined as a minimum 

defined distance and be extinguished 

when the POV exits the forward 

boundary of the defined blind zone. 

Aptiv explained that this should reduce 

consumer confusion since the driver 

should be able to visually see the 

vehicle outside of the blind zone by this 

point, but the BSW could still be 

illuminated. 

NHTSA also received comments on 

test applicability. Specifically, several 

commenters suggested that the Agency 

should only test blind spot systems that 

cannot be disabled by the driver. 

Response to Comments and Agency 

Decisions 

The original lane width specifications 

for BSW and BSI testing of 3.7 to 4.3 m 

(12.0 to 14.0 ft.) were selected to overlap 

with American Association of State 

Highway and Transportation Officials 

(AASHTO) recommendations,338 to 

promote consistency with other NHTSA 

ADAS test procedures, and to allow 

flexibility to contract laboratories which 

could perform blind spot system testing. 

However, NHTSA’s intent is to consider 

harmonization with other global testing 

programs wherever possible. Because of 

this strong interest, lane width 

specifications for BSW and BSI testing 

have been revised to be 3.5 to 3.7 m 

(11.5 to 12 ft.), consistent with Euro 

NCAP’s lane width requirements. 

NHTSA agrees with Bosch that 

alignment with elements of ISO 

standards (in addition to elements of 

other testing programs such as those in 

Euro NCAP) should lessen complexity 

and burden on vehicle manufacturers. 

Regarding harmonization with ISO 

17387:2008 for BSW testing, several 

revisions have been made to better align 

the Agency’s testing protocol and this 

ISO standard. Changes to the definition 

of the two-dimensional polygon 

representing the SV and POV, the range 

of POV lateral velocities used during the 

Straight Lane Converge and Diverge test, 

and the maximum SV blind zone width 

specification were made in response to 

the November 2019 publication of the 

draft BSW procedures. As noted earlier 

in this section, specific changes made in 

response to that earlier publication are 

reflected in updated BSW test 

procedures published in the docket for 

this notice. 

NHTSA also concurs with 

commenters suggesting edits to the 

onset and termination headways in 

BSW testing. As such, the test procedure 

has been revised to clarify that the onset 

of the BSW is unrestricted and to state 

that the warning must be presented by 

a time no later than 300 ms after any 

part of the POV enters the SV blind 

zone, defined earlier. The intent of the 

onset requirement was to ensure that the 

BSW is presented by a certain time, not 

to restrict it from appearing earlier. 

Additionally, NHTSA has amended the 

duration of the required alert; the alert 

must remain on while any part of the 

POV resides within the SV blind zone 

during converge lane changes. For the 

Converge and Diverge test scenario, the 

alert must not be active once the lateral 

distance between the SV and the POV 

is greater than 6 m (19.7 ft.). For the 

Pass-by scenario, the alert must not be 

active once the longitudinal distance 

between the frontmost part of the SV 

and the rearmost part of the POV 

exceeds the BSW termination distances 

provided in the test procedure. These 

range in length from 2.2 m (7.3 ft.) for 

the 80.5 kph (50 mph) condition to 8.9 

m (29.3 ft.) for the 104.6 kph (65 mph) 

condition. 

Finally, to provide as much 

information as possible to consumers 

regarding BSW and BSI systems in new 

vehicles, at this time, NHTSA will not 

consider whether the system may be 

disabled when it provides assessment 

results to the public. Thus, all BSW and 

BSI systems will be eligible for NCAP 

credit. However, to receive credit for 

BSW and BSI systems during program 

testing, NHTSA will require the BSW or 

BSI systems to appear ‘Default ON’ 

during each ignition/key cycle. The 

Agency does not expect blind spot 

technology’s already high consumer 

satisfaction to decrease because of this 

requirement. NHTSA also expects 

drivers will adjust their system’s 

settings to meet their personal 

preferences instead of disengaging the 

system altogether. 

11. Future Considerations 

Use of Additional Test Devices 

As mentioned in the March 2022 RFC, 

in response to prior RFC notices, many 

commenters previously recommended 

that the Agency expand blind spot 

system testing requirements to include 

motorcycle and bicycle detection. In 

response to the Agency’s latest RFC, 

Somerville Bicycle Safety also voiced 

support for NHTSA using bicycle test 

devices in its BSW testing, stating that 

Euro NCAP is already performing this 

testing. Others also agreed that 

bicyclists should be accounted for in 

BSW and BSI testing. MIC/MSF, Lidar 

Coalition, and AMA requested that a 

motorcyclist test device be added so that 

manufacturers design their vehicles to 

recognize motorcyclist signatures. Many 

commenters also noted that 

motorcyclists and bicyclists are 

inherently more vulnerable to serious 

and fatal injuries as compared with 

occupants of motor vehicles. 

Incorporate Other Scenarios or 

Technology 

Many commenters suggested that 

NHTSA ensure all ADAS technologies 

assessed, including BSW and BSI, 

perform to a high standard in order to 

receive credit or the highest rating 

possible. This included good 

performance in darkness, in inclement 

weather, and while turning. The Agency 

has also received similar comments in 

response to prior RFC notices. 

Many commenters also recommended 

that NHTSA address other potential 

blind zones drivers may experience. In 

addition to the lateral blind zones 

assessed for motor vehicle presence in 

the Agency’s BSW/BSI test procedures, 

commenters asserted that NHTSA 

should address blind zones to the front 

and rear of the vehicle, which may also 

exist, particularly in large vehicles, as 

they may create a potentially hazardous 

situation for VRUs. Many commenters 


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339Swanson, E., Azeredo, P., Yanagisawa, M., & 

Najm, W. (2018, September), Pre-Crash Scenario 

Characteristics of Motorcycle Crashes for Crash 

Avoidance Research (Report No. DOT HS 812 902), 

Washington, DC: National Highway Traffic Safety 

Administration. In Press. 

340NHTSA Traffic Safety Facts, June 2022, 

Bicyclists and Other Cyclists, DOT HS 813 322. 

341The report, Assessment of Light Vehicle ADAS 

Crash Avoidance Technologies in Response to TwoWheeled Vehicles as Principal Other Vehicles, can 

be found in the docket for this notice. 

342LDW alerts the driver when the car 

approaches or crosses lane markings, LKA gives 

steering support to assist the driver in preventing 

the vehicle from departing the lane, and LCA 

provides automatic steering to continually center 

the vehicle in its lane. 343Wang, J.-S. (2019, March), Target crash 

population for crash avoidance technologies in 

passenger vehicles (Report No. DOT HS 812 653), 

Washington, DC: National Highway Traffic Safety 

Administration. 

344When only serious injuries (i.e., MAIS 3–5 

injuries) were considered, lane keeping crashes 

represented the highest number of non-fatal injuries 

(21,282 or 0.76 percent of all non-fatal injuries), 

followed by rear-end crashes (17,918 or 0.64 

percent), forward pedestrian crashes (5,973 or 0.21 

percent), blind spot crashes (3,476 or 0.12 percent), 

and backing crashes (454 or 0.02 percent). 

345NHTSA-recommended technologies are driver 

assistance technologies for which the Agency has 

developed performance tests and metrics, and 

which meet the four prerequisites for inclusion. 

noted that assessments for these blind 

spots were not proposed and requested 

that the Agency take them into 

consideration when developing BSW 

and/or BSI procedures. 

Response to Comments and Agency 

Decisions 

Use of Additional Test Devices 

As mentioned in its 2022 RFC notice, 

NHTSA agrees that BSW and BSI 

systems capable of detecting 

motorcycles and bicyclists would 

improve safety. A review of the 2011– 

2015 FARS and GES data sets 339

showed there were 106 fatal crashes and 

nearly 5,100 police-reported crashes 

annually, on average, for same-direction 

lane change crashes involving a vehicle 

and motorcycle. In comparison, there 

were 542 fatalities and 503,070 policereported crashes annually, on average, 

for lane change crashes involving motor 

vehicles. These data show that although 

more motor vehicle occupants than 

motorcyclists die in lane changing 

crashes, the fatality rate for 

motorcyclists is greater than that for 

vehicle occupants, as several 

commenters asserted. While the Agency 

is not aware of specific crash data for 

pedalcyclist lane change crashes 

involving light vehicles, NHTSA 

recognizes that cyclist fatalities are on 

the rise, as there were 938 pedalcyclist 

fatalities in 2020, representing a 9 

percent increase over 2019. Pedalcyclist 

fatalities accounted for 2.4 percent of all 

traffic fatalities and 38,886 pedalcyclist 

injuries that year.340

At this time, the Agency has decided 

to prioritize testing of BSW and BSI 

systems on motor vehicles (excluding 

motorcycles) for NCAP. NHTSA 

maintains that a focus on vehicle 

detection is a reasonable initial step 

forward and that performing blind spot 

system testing on light vehicles, 

particularly at higher POV closing 

speeds, should encourage development 

of robust sensing systems, which may 

improve the detection of VRUs such as 

motorcyclists and bicyclists. The 

Agency has conducted preliminary 

research designed to evaluate vehicle 

response to VRUs. 

As part of this research effort, 

conducted under contract with the 

Transportation Research Center Inc. 

(TRC Inc.), the Agency utilized its 

current BSI test procedures but varied 

the POV test device (e.g., GVT and 

motorcycle) and the SV/POV speed (as 

applicable, depending on test 

scenario).341 NHTSA found that, overall, 

the vehicles tested displayed 

performance differences between the 

surrogate passenger vehicle (i.e., GVT) 

and the surrogate motorcycle test device 

in the lane change scenarios assessed. 

For instance, one vehicle was able to 

detect the GVT in a blind spot for all test 

speeds for the SV Lane Change, 

Constant Headway tests but did not 

issue a detection alert when the 

motorcycle test device was within the 

blind spot. A similar observation was 

made for a vehicle in the SV Lane 

Change, Closing Headway BSI scenario. 

The vehicle failed to issue a blind spot 

warning at 40 kph (24.9 mph) when the 

motorcycle test device was within its 

blind spot, but it appropriately issued 

an alert for the GVT at this test speed. 

From this, it can be concluded that 

incorporating a motorcycle test device 

into the Agency’s current blind spot test 

procedures would help to address these 

specific collision types. 

NHTSA also plans additional research 

focused on characterizing the 

capabilities and limitations of available 

BSI systems, both on-road and closed 

track. As part of this work, the Agency 

plans to review crash datasets and 

develop additional test scenarios for 

motorcycles and/or bicyclists to align 

with the safety need. Further, as noted 

in the NCAP Roadmap section in this 

final decision notice, NHTSA plans to 

implement in NCAP BSW and BSI 

evaluation to mitigate crashes with 

motorcyclist and bicyclist crashes 

starting with model year 2031 vehicles. 

Incorporate Other Scenarios or 

Technology 

While NHTSA recognizes the need to 

assure crash avoidance systems perform 

well under all situations that a driver 

may encounter, it is not currently 

practical to evaluate each within the 

scope of NCAP. Therefore, the most 

frequent fatal and injurious conditions 

will be prioritized for evaluation. When 

BSW and BSI systems perform 

acceptably in these conditions (i.e., 

clear, daylight, straight and flat road) 

and are present in the fleet in sufficient 

numbers, NHTSA will evaluate realworld conditions at that time to 

determine whether additional 

condition(s) should be subsequently 

addressed. 

The Agency also acknowledges 

commenter concerns regarding driver 

visibility. Commenters noted that 

certain vehicles, including large 

vehicles such as pickup trucks and 

SUVs, may have additional blind zones 

to the front and rear of the vehicle. As 

mentioned in the NCAP Roadmap 

section of this notice, NHTSA is 

currently conducting research on driver 

visibility to mitigate VRU injuries and 

fatalities. The results of this research 

will inform the Agency on the most 

appropriate approach to reduce harm to 

these difficult-to-see VRUs. 

VII. Updating Lane Keeping 

Technologies 

NHTSA has decided to (1) retain its 

assessment for lane departure warning 

(LDW) and to (2) add an assessment for 

lane keeping assist (LKA) for this NCAP 

update. As mentioned in the Agency’s 

March 2022 RFC, lane keeping 

technologies, including LDW, LKA, and 

LCA,342 can address ten pre-crash 

scenarios, including roadway departure 

scenarios and those in which the SV 

passively crosses the centerline or 

center median and strikes a vehicle 

travelling in the opposite direction. 

These scenarios resulted in 1.13 million 

crashes (19 percent of all U.S. crashes), 

14,844 fatalities (44 percent of all 

fatalities), and 479,939 MAIS 1–5 

injuries (17 percent of all injuries 

recorded), annually on average between 

2011 and 2015, showing there is a 

significant safety need.343 344

A. Lane Keeping Technologies 

1. Lane Departure Warning (LDW) 

LDW is a NHTSA-recommended 

technology 345 currently included in 

NCAP to mitigate the aforementioned 

lane departure crashes in which a driver 

unintentionally allows a vehicle to drift 

out of its lane of travel. LDW systems 

often use camera-based sensors to detect 


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346Botts’ Dots are round, raised, non-reflective, 

pavement markers that mark travel lanes. 

347Note that performance of LDW systems may be 

adversely affected by precipitation or poor roadway 

conditions due to construction, unmarked 

intersections, faded/worn/missing lane markings, 

markings covered with water, etc. 

348 73 FR 40033 (July 11, 2008). 

349 Insurance Institute for Highway Safety (2017, 

August 23), Lane departure warning, blind spot 

detection help drivers avoid trouble, https://

www.iihs.org/news/detail/stay-within-the-lineslane-departure-warning-blind-spot-detection-helpdrivers-avoid-trouble. 

350Flannagan, C. and Leslie, A. (2020). Crash 

Avoidance Technology Evaluation Using RealWorld Crash Data (No. DOT HS812 841). United 

States. Department of Transportation. National 

Highway Traffic Safety Administration. 

351Aukema, A., Berman, K., Gaydos, T., 

Sienknecht, T., Chen, C.-L., Wiacek, C., Czapp, T., 

& St. Lawrence, S. (2023) Real-World Effectiveness 

of Model Year 2015–2020 Advanced Driver 

Assistance Systems. 27th International Technical 

Conference on the Enhanced Safety of Vehicles, 

Paper Number 23–0170. 

352The eight participating industry partners that 

provided vehicle data for this study are American 

Honda Motor Co., Inc., General Motors LLC, Mazda 

North American Operations, Mitsubishi Motors 

R&D of America, Inc., Nissan North America, Inc., 

Stellantis (FCA US LLC), Subaru Corporation, and 

Toyota Motor North America, Inc. 

353 Insurance Institute for Highway Safety (2016, 

January 28), Most Honda owners turn off lane 

departure warning, Status Report, Vol. 51, No. 1, 

page 6. 

354Wiacek, C., Firey, L., and Mynatt, M. (2023). 

EDR Reported Driver Usage of Crash Avoidance 

Systems for Honda Vehicles. Paper Number 23– 

0040. 27th International Technical Conference on 

the Enhanced Safety of Vehicles. 

355Flannagan, C., LeBlanc, D., Bogard, S., 

Nobukawa, K., Narayanaswamy, P., Leslie, A., 

Kiefer, R., Marchione, M., Beck, C., and Lobes, K. 

(2016, February), Large-scale field test of forward 

collision alert and lane departure warning systems 

(Report No. DOT HS 812 247), Washington, DC: 

National Highway Traffic Safety Administration. 356Consumer Reports (2019, November), 

Consumer Perceptions of ADAS, https://

data.consumerreports.org/reports/consumerperceptions-of-adas/. 357Wang, J.-S. (2019, March), Target crash 

population for crash avoidance technologies in 

passenger vehicles (Report No. DOT HS 812 653), 

Washington, DC: National Highway Traffic Safety 

Administration. 

lane markers, such as solid lines 

(including those marked for bike lanes), 

dashed lines, or raised pavement 

markers such as Botts’ Dots 346 used to 

delineate the vehicle’s travel lane.347

When a LDW system detects that a 

vehicle is laterally approaching or 

crossing a lane marking, the system 

presents an alert to warn the driver of 

the unintentional shift so the driver can 

steer the vehicle back into its lane. LDW 

alerts may be visual, auditory, and/or 

haptic in nature. Visual alerts may show 

which side of the vehicle is departing 

the lane, and examples of haptic alerts 

include steering wheel or seat vibrations 

to alert the driver. If the driver’s turn 

signal is activated, the LDW system 

interprets the lane change as an 

intentional act and thus does not alert 

the driver. 

NHTSA proposed adoption of LDW 

systems (along with FCW systems) in its 

NCAP ADAS evaluations starting with 

2011 model year vehicles because these 

systems were deemed to meet the 

Agency’s four prerequisites for 

inclusion at the time.348 While the 

Agency estimated that then-current 

LDW systems were only 6 to 11 percent 

effective in preventing lane departure 

crashes, NHTSA cited the large number 

of road departure and opposite direction 

crashes occurring on the nation’s 

roadways as well as the resulting AIS 3+ 

injuries as reasons to include LDW in 

NCAP. 

Since LDW’s adoption in NCAP, more 

recent studies have provided varying 

statistics with respect to LDW 

effectiveness. In a 2017 study,349 IIHS 

concluded that LDW systems were 

effective at reducing three types of 

passenger car crashes (single-vehicle, 

sideswipes, and head-on) by 11 percent, 

which is the same rate NHTSA 

originally estimated. Further, IIHS also 

concluded that LDW systems reduce 

injuries in those same types of crashes 

by 21 percent. UMTRI, however, found 

in its study of real-world effectiveness 

of crash avoidance technologies in GM 

vehicles that LDW systems showed only 

a 3 percent reduction (determined to be 

not statistically significant) for 

applicable crashes.350 A second, more 

recent study 351 conducted by the 

Partnership for Analytics Research in 

Traffic Safety (PARTS) also showed 

more limited effectiveness for LDW 

systems. In the PARTS study, policereported crash data (2016 to 2021) from 

13 states was combined with vehicle 

equipment data from 47 million 

vehicles from eight 352 vehicle 

manufacturers, representing 93 vehicle 

models spanning from model years 2015 

to 2020. The resulting study dataset of 

2.4 million crash-involved vehicles did 

not find a significant reduction in 

single-vehicle road departure crashes for 

vehicles equipped with LDW alone. 

Other studies have suggested reasons 

for lower LDW effectiveness rates, one 

of which is higher driver deactivation 

rates caused by dissatisfaction with 

system functionality. In a survey of 

Honda vehicles brought into Honda 

dealerships for service,353 IIHS 

researchers found that out of 184 

vehicles equipped with an LDW system, 

only a third of the vehicles had the 

system activated. 

In a similar study,354 150 crashinvolved Honda vehicles equipped with 

Event Data Recorders (EDRs) that 

captured data elements related to the 

function and alert status of several crash 

avoidance systems in the time leading 

up to the crash event were analyzed 

from NHTSA’s 2017–2021 Crash 

Investigation Sampling System (CISS). 

Starting with the 2016 model year, 

Honda began to phase-in vehicles 

equipped with an EDR that captures the 

status and activation of crash avoidance 

technologies such as FCW/AEB and 

LDW/LKA. The EDR data were assessed 

to identify the use and activation 

statuses of these crash avoidance 

technologies at the time of the 

associated crash events. The results 

indicated that drivers of Honda vehicles 

equipped with crash avoidance systems 

were much more likely to have FCW/ 

AEB systems ‘‘On’’ and LDW/LKA 

systems ‘‘Off.’’ Specifically, 99 percent 

of drivers for this study had FCW/AEB 

systems ‘‘On’’ in the time leading up to 

the crash and thus could be afforded the 

benefits of these systems. With respect 

to LDW/LKA systems, 49 percent of the 

drivers had these systems ‘‘Off’’ at the 

time of the crash, and therefore were not 

afforded the benefits of these systems. 

Differences were not identified for 

drivers that had the LDW/LKA system 

‘‘On’’ compared to those that had it 

‘‘Off’’ with respect to the driver’s sex, 

age, and race/ethnicity. 

Further, in its telematics-based study 

on LDW usage,355 UMTRI found that, 

overall, drivers turned off LDW systems 

50 percent of the time. However, in 

Consumer Reports’ August 2019 survey 

of more than 57,000 CR subscribers, the 

organization found that 73 percent of 

vehicle owners reported they were 

satisfied with LDW technology.356

In its March 2022 RFC notice, the 

Agency proposed to continue to include 

LDW assessments in NCAP, as the 

system’s adoption rate has not increased 

as significantly as that for FCW since 

the inclusion of both technologies in the 

program. When LDW was introduced in 

NCAP, its fitment rate was less than 0.2 

percent.357 For the 2018 model year, the 

fitment rate for LDW was 30 percent. In 

contrast, the fitment rate for FCW saw 

an approximate 40 percent increase over 

the same period. Since LDW technology 

is currently not being offered as 

standard equipment on all passenger 

vehicles, the Agency reasons that it 

remains important for NCAP to continue 

to recommend the technology to new 

vehicle purchasers and inform shoppers 

which vehicles have systems that meet 

NHTSA’s performance criteria. 

Furthermore, in recent years, many 

vehicle manufacturers have made 

improvements to sensors utilized by 

LDW systems for the purposes of 

implementing SAE Driving Automation 


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358National Highway Traffic Safety 

Administration. (2013, February). Lane departure 

warning system confirmation test and lane keeping 

support performance documentation. See http://

www.regulations.gov, Docket No. NHTSA–2006– 

26555–0135. 

359The two-dimensional polygon is defined by 

the vehicle’s axles in the X-direction (fore-aft), the 

outer edge of the vehicle’s tire in the Y-direction 

(lateral), and the ground in the Z-direction 

(vertical). 

360LKA differs from another active lane keeping 

technology, lane centering assist (LCA). LKA assists 

the driver by providing short-duration steering and/ 

or braking inputs when a lane departure is 

imminent or underway; LCA provides continuous 

assistance to the driver to keep their vehicle 

centered within the lane. 

361Flannagan, C. and Leslie, A. (2020). Crash 

Avoidance Technology Evaluation Using RealWorld Crash Data (No. DOT HS812 841). United 

States. Department of Transportation. National 

Highway Traffic Safety Administration. 

362Aukema, A., Berman, K., Gaydos, T., 

Sienknecht, T., Chen, C.-L., Wiacek, C., Czapp, T., 

& St. Lawrence, S. (2023) Real-World Effectiveness 

of Model Year 2015–2020 Advanced Driver 

Assistance Systems. 27th International Technical 

Conference on the Enhanced Safety of Vehicles, 

Paper Number 23–0170. 

363Spicer, R., Vahabaghaie, A., Murakhovsky, D., 

Bahouth, G. et al., (2021). ‘‘Effectiveness of 

Advanced Driver Assistance Systems in Preventing 

System-Relevant Crashes,’’ SAE Technical Paper 

2021–01–0869. doi:10.4271/2021-01-0869. 

Level 2 systems such that LDW system 

effectiveness may improve, and 

consumer dissatisfaction may wane. 

Some of today’s systems can assess if 

the driver is actively steering by 

measuring steering rate or torque on the 

steering wheel, or by utilizing direct or 

indirect driver monitoring systems. 

Furthermore, the sensing capability 

exists to suppress unnecessary LDW 

alerts and LKA activations in situations 

that require driving over a lane marker 

without the use of the turn signal, such 

as when trying to pass a bicyclist or 

drive around a pothole. Finally, since 

the Agency is also adopting LKA as part 

of this upgrade to NCAP, continuing to 

assess LDW functionality in addition to 

LKA, similar to assessing FCW in 

addition to AEB, and BSW in addition 

to BSI, should provide the greatest 

safety gains and most effectively address 

the number of fatalities and injuries 

related to lane departure crashes. 

NCAP’s Current Lane Departure 

Warning Test Procedure 

In its March 2022 RFC notice, NHTSA 

proposed to continue its assessment of 

LDW systems under NCAP using the 

current NCAP test procedure titled, 

‘‘Lane Departure Warning System 

Confirmation Test and Lane Keeping 

Support Performance Documentation,’’ 

dated February 2013.358 This protocol 

assesses the system’s ability to issue an 

alert in response to a driving situation 

intended to represent an unintended 

lane departure and to quantify the test 

vehicle’s position relative to the lane 

line at the time of the LDW alert. 

In NCAP’s LDW tests, a test vehicle is 

accelerated from rest to a test speed of 

72.4 kph (45 mph) while travelling in a 

straight line, parallel to a single lane 

line, comprised of one of three marking 

types: continuous white lines, 

discontinuous (i.e., dashed) yellow 

lines, or discontinuous raised pavement 

markers (i.e., a combination of Botts’ 

Dots and other retro reflective pavement 

markers). The test vehicle is driven such 

that the centerline of the vehicle is 

approximately 1.8 m (6 ft.) from the lane 

edge. This path must be maintained, 

and the test speed must be achieved, at 

least 61.0 m (200 ft.) prior to the start 

gate. Once the driver reaches the start 

gate, they manually input sufficient 

steering to achieve a lane departure with 

a target lateral velocity of 0.5 m/s (1.6 

ft./s) with respect to the lane line. The 

driver of the vehicle does not activate 

the turn signal at any point during the 

test and does not apply any sudden 

inputs to the accelerator pedal, steering 

wheel, or brake pedal. The test vehicle 

is driven at a constant speed throughout 

the maneuver. The test ends when the 

vehicle crosses at least 0.5 m (1.7 ft.) 

over the edge of the lane line marking. 

The scenario is performed for two 

different departure directions, left and 

right, and for all three lane marking 

types, resulting in a total of six test 

conditions. Five repeated trials runs are 

performed per test condition. 

LDW performance for each test trial is 

evaluated by examining the proximity of 

the vehicle with respect to the edge of 

a lane line at the time of the LDW alert. 

The LDW alert must not be issued when 

the lateral position of the vehicle, 

represented by a two-dimensional 

polygon,359 is greater than 0.75 m (2.5 

ft.) from the inboard edge of the lane 

line (i.e., the line edge closest to the 

vehicle when the lane departure 

maneuver is initiated), and must be 

issued before the lane departure exceeds 

0.3 m (1 ft.). To pass the test, the LDW 

system must satisfy the pass criteria for 

three of the first five valid individual 

trials for each combination of departure 

direction and lane line type (60 percent) 

and for 20 of the 30 trials overall (66 

percent). 

2. Lane Keeping Assist (LKA) 

Much like FCW and BSW, LDW’s 

limitation is that it is merely a warningbased system. These systems do not 

actively mitigate crashes on the driver’s 

behalf. Rather, they require driver input 

for any benefit to be realized. LKA, like 

AEB and BSI, is an active safety system. 

As such, its corrective actions are 

designed to be initiated without driver 

action.360

LKA systems can help prevent an 

unintended lane departure where the 

driver is not using the turn signal, and 

not actively steering (i.e., providing 

little to no steering wheel torque), to 

help prevent: ‘‘sideswiping,’’ where a 

vehicle strikes another vehicle in an 

adjacent lane that is travelling in the 

same direction; opposite direction 

crashes, where a vehicle crosses the 

centerline and strikes another vehicle 

travelling in the opposite direction in an 

adjacent lane; and road departure 

crashes, where a vehicle runs off the 

road, resulting in a rollover crash or an 

impact with a tree or other object. In 

addition, LKA systems may also help to 

prevent unintended lane departures into 

designated bicycle lanes. 

LKA systems typically utilize the 

same sensor(s) used by LDW systems to 

monitor the vehicle’s position within 

the lane and determine whether the 

vehicle is about to drift out of its lane 

of travel unintentionally. Because LKA 

systems help to guide a vehicle back 

into its lane without driver action, they 

further enhance safety beyond that 

achieved by LDW alone. 

In its study of real-world effectiveness 

of ADAS technologies, UMTRI found 

that LKA (when combined with lane 

departure warning functionality) 

showed an estimated 30 percent 

reduction in applicable crashes, 

whereas, as mentioned previously, LDW 

systems alone showed a reduction of 

only 3 percent, which was determined 

to be non-significant.361

While the PARTS study 362 showed 

more limited effectiveness for LKA 

systems, it also highlighted the 

enhanced safety benefits offered by LKA 

compared to LDW systems. This study 

showed that single-vehicle road 

departure crashes were reduced by an 

estimated 8 percent (5 to 12 percent) for 

vehicles equipped with both LDW and 

LKA systems, while, as mentioned 

earlier, the study did not find significant 

results for vehicles equipped with LDW 

alone. Similar effectiveness was 

observed for LKA systems in another 

recent study.363 For this study, 

production data for 11 model year 2015 

through 2018 Toyota models were 

merged with police-reported crash files 

from eight U.S. states for crash years 

2015 through 2019. The results showed 

LKA-equipped vehicles were 9 percent 

less likely to run off the road. However, 

vehicles equipped with LDW and LKA 

did not have a significant effect on risk 

of same-direction sideswipe or head-on 

crashes. As with LDW, the lower 

effectiveness rates for LKA systems stem 


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364 Insurance Institute for Highway Safety (2016, 

January 28), Most Honda owners turn off lane 

departure warning, Status Report, Vol. 51, No. 1, 

page 6. 

365Wiacek, C., Firey, L., and Mynatt, M. (2023). 

EDR Reported Driver Usage of Crash Avoidance 

Systems for Honda Vehicles. Paper Number 23– 

0040. 27th International Technical Conference on 

the Enhanced Safety of Vehicles. 

366Consumer Reports. (2019, November), 

Consumer Perceptions of ADAS, https://

data.consumerreports.org/reports/consumerperceptions-of-adas/. 

367European New Car Assessment Programme 

(Euro NCAP) (2019, July), Test Protocol—Lane 

Support Systems, Version 3.0.2. See section 7.2.5, 

Lane Keep Assist (LKA) tests. 

368European New Car Assessment Programme 

(Euro NCAP) (November 2022), Test Protocol—Lane 

Support Systems, Implementation 2023. Version 

4.2. Note that the Euro NCAP LSS test protocol has 

been updated from Version 3.0.2 since the March 

2022 RFC’s publication. 

369Swanson, E., Foderaro, F., Yanagisawa, M., 

Najm, W.G., & Azeredo, P. (2019, August), Statistics 

of light-vehicle pre-crash scenarios based on 2011– 

2015 national crash data (Report No. DOT HS 812 

745), Washington, DC: National Highway Traffic 

Safety Administration. 

370Posted speed limit was unknown or not 

reported in 3 percent of fatal road departure crashes 

and in 14 percent of road departure crashes with 

injuries. For opposite direction crashes, these 

figures were 1 percent and 13 percent, respectively. 

371Travel speed was unknown or not reported in 

63 percent of fatal road departure crashes and in 68 

percent of road departure crashes with injuries. For 

opposite direction crashes, these figures were 65 

percent and 67 percent, respectively. 

372Roadway alignment was unknown or not 

reported in 1 percent and 4 percent of fatal and 

injurious road departure crashes, respectively. 

373Roadway alignment was unknown or not 

reported in 1 percent and 2 percent of fatal and 

injurious opposite direction crashes, respectively. 

374Roadway grade was unknown or not reported 

in 4 percent and 19 percent of fatal and injurious 

road departure crashes, respectively. 

375Roadway grade was unknown or not reported 

in 3 percent and 16 percent of fatal and injurious 

opposite direction crashes, respectively. 

from overall driver dissatisfaction with 

combined LDW/LKA system 

functionality. This was evidenced by 

the referenced studies for Honda 

vehicles, discussed previously, which 

found high rates of deactivation with 

LDW/LKA systems.364 365

However, there is also evidence that 

consumers appreciate the inherent 

benefits LKA can provide. In an August 

2019 survey, Consumer Reports found 

that 74 percent of vehicle owners 

reported they were satisfied with LKA 

technology.366 Further, 84 percent of 

model year 2024 vehicles are equipped 

with LKA systems as standard 

equipment. 

Based on these findings on system 

effectiveness and consumer acceptance, 

there is value in adopting LKA in NCAP 

to complement LDW systems and 

prevent or mitigate a greater number of 

lane departure crashes involving 

injuries and fatalities. By adopting 

objective test procedures to gauge LKA 

system performance for NCAP’s 

assessments, the Agency will best 

ensure system robustness for future lane 

keeping systems having enhanced 

capabilities (e.g., lane centering). 

Proposed LKA Test Procedure 

In its March 2022 RFC notice, the 

Agency proposed the adoption of 

certain test methods (e.g., those for 

LKA) contained within the Euro NCAP 

Test Protocol—Lane Support Systems 

(LSS) 367 to assess technology design 

differences for LKA. Since the test 

speeds and road configurations 

specified in Euro NCAP’s protocol are 

similar to those stipulated currently in 

the Agency’s LDW test procedure, 

adopting Euro NCAP’s test protocol 

would allow the Agency to sufficiently 

address the lane keeping crash typology 

currently covered for LDW while also 

harmonizing with the European 

organization. 

Euro NCAP’s current 368 LSS test 

procedure includes a series of LKA 

trials performed with iteratively 

increasing lateral velocities towards the 

desired lane line. Each LKA trial begins 

with the subject vehicle (SV) being 

driven at 72 kph (44.7 mph) down a 

straight lane delineated by a single solid 

white or dashed white line. Initially, the 

SV path is parallel to the lane line, with 

an offset from the lane line that depends 

on what lateral velocity is desired later 

in the maneuver. Then, after a short 

period of steady-state driving, the SV 

transitions to a path defined by a 1,200 

m (3,937.0 ft.) radius curve. The lateral 

velocity of the SV’s approach toward the 

lane line (from both the left and right 

directions) is increased from 0.2 to 0.6 

m/s (0.7 to 2.0 ft./s) in 0.1 m/s (0.3 ft./ 

s) increments or until acceptable LKA 

performance is no longer realized. 

Acceptable LKA performance occurs 

when the SV does not cross the inboard 

leading edge of the lane line by more 

than 0.3 m (1.0 ft.). 

B. Linking Current and Proposed Lane 

Keeping Technology Test Scenarios to 

Real-World Crashes 

NCAP’s current LDW test conditions, 

as well as the future LDW/LKA test 

conditions described in this notice, 

represent pre-crash scenarios that 

correspond to a substantial portion of 

fatalities and injuries observed in realworld lane departure crashes. A review 

of Volpe’s 2011 to 2015 data set showed 

that, when the posted speed limit was 

known, approximately 42 and 31 

percent of fatalities in fatal road 

departure and opposite direction 

crashes, respectively, occurred when the 

posted speed was 72.4 kph (45 mph) or 

less.369 Similarly, the data indicated 74 

and 73 percent of injuries resulted from 

road departure and opposite direction 

crashes, respectively, that occurred 

when the posted speed was 72.4 kph (45 

mph) or less.370 For crashes where the 

travel speed was reported in FARS and 

GES, approximately 17 and 26 percent 

of fatal road departure and opposite 

direction crashes, respectively, occurred 

at travel speeds of 72.4 kph (45 mph) or 

less. These data also showed that, where 

the travel speed was reported, 71 and 78 

percent of the police-reported non-fatal 

road departure and opposite direction 

crashes, respectively, occurred at 72.4 

kph (45 mph) or less.371 While this data 

suggests that speeding is prevalent in 

lane departure relevant pre-crash 

scenarios, particularly ones that result 

in fatalities, a test speed of 72.4 kph (45 

mph) should address a measurable 

portion of the travel speeds where lane 

departure crashes are occurring. 

Volpe’s data analysis also showed the 

predominant roadway configuration for 

real-world lane departure crashes (i.e., 

straight) also corresponds well with 

NCAP’s test procedure. Of those road 

departure crashes in which roadway 

alignment was known, 63 percent and 

78 percent of fatal and injurious crashes, 

respectively, occurred on straight 

roads.372 For opposite direction-related 

crashes where roadway alignment was 

known, 70 percent of crashes with 

fatalities and 68 percent of crashes with 

police-reported injuries occurred on 

straight roads.373 Additionally, for those 

road departure crashes where roadway 

grade was known, 71 percent of fatal 

crashes and 79 percent of crashes with 

injuries occurred on level roads.374 For 

opposite direction crashes, these values 

were 68 percent and 69 percent, 

respectively.375

C. NHTSA’s Proposals, Summary of 

Comments, Response to Comments, and 

Agency Decisions 

1. Lane Keeping Technology Inclusion 

in General 

Most commenters supported the 

inclusion of active lane keeping 

technology in NCAP. Respondents in 

favor of keeping LDW and additionally 

incorporating LKA included advocacy 

groups, vehicle manufacturers, and 

individuals alike. Families for Safe 

Streets called LKA a ‘‘critical safety 

feature,’’ MEMA suggested that it is 

‘‘ripe’’ for inclusion, and, like blind spot 

technologies, ITS America stated that 

NHTSA provided sufficient data to 

support adding it to NCAP’s suite of 

testing. HMNA requested that LKA, 

along with the other four ADAS 


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376See NHTSA–2021–0002–3856, Attachment A 

for more information. 

377Commission Implementing Regulation (EU) 

2021/646 of 19 April 2021 laying down rules for the 

application of Regulation (EU) 2019/2144 of the 

European Parliament and of the Council as regards 

uniform procedures and technical specifications for 

the type-approval of motor vehicles with regard to 

their emergency lane-keeping systems (ELKS) 

[2021] OJ L133/31, § 3.5.3.1.2. 

features, should be added to NCAP ‘‘as 

soon as possible.’’ Having said this, a 

number of commenters cautioned the 

Agency to ensure that active lane 

keeping technologies do not interfere 

with a driver’s attempt to pass a 

bicyclist or pedestrian at a safe distance. 

2. Removal or Integration of LDW 

In its March 2022 RFC notice, the 

Agency noted that it agreed with 

commenters to the 2015 RFC notice who 

recommended that NHTSA adopt LKA 

technology in NCAP. However, instead 

of replacing LDW with LKA, as many 

commenters suggested, the Agency 

expressed that integrating its 

assessments for LDW into those for LKA 

may be a better approach to consider. 

Such a method (inclusive of passive and 

active safety capabilities for lane 

support systems) would be similar to 

that which the Agency has adopted for 

forward collision avoidance systems, 

FCW and AEB, as detailed earlier. 

As mentioned, the Agency proposed 

to adopt Euro NCAP’s LKA test 

scenarios to assess technology design 

differences for LKA, and since the test 

speeds and road configurations 

specified in Euro NCAP’s LSS protocol 

are similar to those stipulated in the 

Agency’s current LDW test procedure, 

NHTSA stated that the Euro NCAP tests 

should sufficiently address the lane 

keeping crash typology for LDW as well. 

As such, NHTSA solicited comment on 

whether it should retain its separate 

LDW test protocol or integrate an LDW 

requirement into the LKA test procedure 

it ultimately adopts. The Agency 

suggested that for systems having both 

LDW and LKA capabilities, it would 

simply turn off LKA to conduct the 

LDW test if both systems are to be 

assessed separately. 

Summary of Comments 

Many commenters, including ASC, 

Advocates, Aptiv, BMW, Bosch, GM, 

HATCI, IDIADA, Intel, Toyota, and TRC 

supported integrating the LDW 

assessment into the LKA test procedure. 

Integrate Because of Testing Benefits 

Test laboratories IDIADA and TRC 

supported consolidating the LDW and 

LKA test procedures because doing so 

offered ‘‘an advantage for those 

conducting the test’’ (TRC) and was 

‘‘more convenient’’ (IDIADA). GM also 

added that integrating the two test 

procedures would enhance 

efficiency.376

Turn Off LKA Functionality To Assess 

LDW 

ASC, Honda, TRC, and Aptiv 

supported turning the LKA system off to 

evaluate LDW, with ASC and Aptiv also 

expressing support for evaluating LDW 

alone if LKA is not available. Having 

said this, Aptiv stated that integrating 

the LDW and LKA assessments may 

help drive offerings of LKA. TRC 

mentioned that many of the scenarios 

and line types are already similar and 

that separate assessments would be easy 

to perform by turning off the LKA 

feature to conduct LDW tests. 

Integrate, But Assess as a System, Not 

Separately 

Auto Innovators recommended that 

since LDW and LKA interact together in 

the real world, and the combined 

system offers greater safety benefits than 

individual systems, assessments should 

be integrated to reduce test burden. The 

group suggested that LDW should not be 

assessed separately if LKA is provided, 

especially since not all systems allow 

disabling of LDW and/or LKA. The 

group generally supported 

harmonization with Euro NCAP’s LSS 

protocol. 

GM also supported an assessment of 

overall system performance. Like Auto 

Innovators, the automaker did not agree 

with assessing LDW functionality 

separately for those vehicles equipped 

with active lane keeping features. The 

commenter mentioned that not only is 

the ability to turn off LKA 

independently from LDW not an option 

for most vehicles, but the Agency’s 

proposal would both limit potential 

safety benefits [for LKS] and also 

continue to allow nuisance behavior 

from LDW systems. The manufacturer 

further asserted that adopting protocols 

that assess LDW functionality separately 

(within an LKA system) would limit 

optimization of feature behavior since 

modern lane keeping systems integrate 

LDW into LKA, such that the passive 

warning serves as a secondary alert to 

the active system (e.g., LKA, lane 

centering). In consideration of these 

comments, GM advocated that NHTSA 

only assess LDW functionality in cases 

where LKA fails to keep the vehicle in 

the lane per the test procedure 

requirements (regardless of whether the 

Agency maintains LDW as a separate 

assessment or integrates LDW 

assessments into an LKS test 

procedure). 

Similarly, Auto Innovators and 

Toyota commented that NHTSA should 

evaluate LKA performance first, and if 

the Agency’s performance criteria is not 

met, only then should LDW 

performance be evaluated. Auto 

Innovators and BMW, in addition to 

GM, as mentioned above, agreed that 

passing LKA systems should 

automatically receive credit for LDW 

(no separate LDW assessment should be 

necessary). GM stated that this would be 

consistent with the current Work in 

Progress (WIP) of SAE J3240, whereas 

Auto Innovators and BMW cited EU 

emergency lane-keeping systems (ELKS) 

regulations, which consider steering 

and/or braking intervention to be a 

haptic LDW warning.377 Intel 

recommended that the Agency award 

additional points to LKA compared to 

LDW, since LKA can automatically 

prevent lane departures. HATCI also 

recommended that the Agency combine 

LDW and LKA requirements for vehicles 

having LKA functionality and retain a 

separate LDW assessment for those 

vehicles that do not. The manufacturer 

went on to say that it supports most of 

the test methods in Euro NCAP’s LSS 

protocol because the safety need in the 

U.S. is similar. 

Integrate LDW and LKA, But Continue 

To Test LDW Separately in Certain 

Instances 

Some commenters agreed with 

combining LDW and LKA assessments 

but stated that LDW functionality 

should still be assessed separately for 

stand-alone LDW systems, or in 

instances where LKA can be disabled 

such that the system offers independent 

LDW functionality. In such cases, Bosch 

recommended performing Euro NCAP’s 

single line LKA tests to assess 

performance for the LDW system. 

Advocates also supported aligning with 

Euro NCAP’s LSS procedure and 

combining LDW and LKA testing if the 

Agency could justify doing so, but also 

mentioned that Euro NCAP’s protocol 

specifies certain scenarios for LDW-only 

systems and systems that offer 

independent LDW functionality. The 

group also mentioned that the Agency 

should ‘‘[rate] both LDW and LKS’’ and 

weight the technology offering the 

greater safety benefits higher. Finally, 

IDIADA suggested LKA should have a 

performance-based assessment whereas 

LDW could be assessed based on fitment 

alone since LDW offers a much smaller 

safety benefit than LKA. 


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378ASC estimated that 85 percent of U.S. vehicles 

have electric power steering in 2022 and this 

number will increase to 92 percent in 2027. 

379European New Car Assessment Programme 

(Euro NCAP) (July 2019), Test Protocol—Lane 

Support Systems, Version 3.0.2. 

380European New Car Assessment Programme 

(Euro NCAP) (December 2023), Test Protocol—Lane 

Support Systems, Version 4.3. 

Do Not Integrate LDW and LKA 

Contrary to commenters who stated 

that the LDW and LKA assessments 

could be integrated, ZF Group and CAS 

recommended that LDW and LKA 

assessments be kept separate, 

particularly if either system can be 

disabled. DRI agreed. The test laboratory 

mentioned that it has seen varying 

performance for LDW depending on 

whether LKA was enabled or disabled, 

noting that when LKA was enabled, 

some vehicles would suppress the LDW 

alert as the LKA system attempted to 

intervene and keep the vehicle inside 

the lane, and then, when the 

intervention was not successful, the 

vehicle issued the LDW alert after the 

vehicle had departed from the lane. DRI 

further noted when LKA was disabled 

in those same vehicles, the LDW alerts 

were issued much earlier. As such, DRI 

concluded that, for vehicles where LDW 

and LKA are user selectable, vehicle 

manufacturers may vary the time of the 

LDW alert based on whether LKA is 

enabled. The test laboratory also noted 

that some LKA systems may intervene 

to the extent that one would have to 

impart additional steering toward the 

lane line (which may also suppress 

LDW if the vehicle senses the steering 

is intentional) to position the vehicle 

close enough to the lane line to issue an 

LDW alert. 

Rivian recommended the Agency 

perform separate assessments of LDWonly, LKA-only, and LDW and LKA in 

combination. The manufacturer 

commented that this was most 

appropriate, particularly for userconfigurable systems, to allow 

consumers to understand the safety 

benefits of each system individually and 

in combination. 

Other Related Comments 

Although Honda did not express a 

preference for removal of LDW or 

integration of the system into LKA, the 

automaker did support adoption of the 

LSS protocol used by Euro NCAP. Intel 

also expressly supported adopting the 

Euro NCAP protocol. 

FCA opined that the current LDW test 

procedure should be maintained for a 

transitional period of time before a new 

requirement is implemented. Similarly, 

ASC and Aptiv mentioned the need to 

continue to perform LDW-only 

assessments, at least initially, noting 

that not all vehicles are currently 

equipped with LKA because they do not 

have electric power steering.378

Tesla stated that LDW points in Euro 

NCAP can be obtained either through 

the performance evaluation of an LDW 

system or presence of a BSI system; 

however, the automaker stated that 

NHTSA should evaluate the 

performance of LDW (rather than just 

presence) and BSI systems separately to 

ensure safety benefits for both systems 

are realized. Auto Innovators also noted 

that Euro NCAP’s LSS test procedure 

contains the ELK—Overtaking scenario 

analogous to a scenario in NHTSA’s BSI 

test procedure. However, the group 

suggested that the Agency keep LKA 

and BSI separate from one another since 

the U.S. market has accepted them as 

separate systems. 

Response to Comments and Agency 

Decisions 

The Agency has chosen to integrate 

LDW and LKA testing, and as such, will 

evaluate LDW functionality during its 

LKA tests. 

Many commenters noted that LDW 

and LKA are two components of a larger 

lane departure mitigation system. Not 

only is it possible for the two systems 

to be enmeshed such that one may not 

be operational if the other is turned off, 

but the Agency’s goal is for drivers to 

find lane keeping technologies 

supportive of the driving task and 

therefore leave them enabled. As Auto 

Innovators reiterated, the safety benefits 

of both systems together are greater than 

the benefits of a single system on its 

own. This improved safety cannot be 

realized if consumers choose to disable 

one or both of these systems. This holds 

true even if manufacturers choose to 

tune their LDW and/or LKA systems to 

compensate for the other system being 

turned off, for those vehicles which 

offer the option to do so. Although 

drivers may disable one or both systems 

according to their preference, the 

Agency finds it most advantageous to 

the consumer to integrate both 

components in its lane keeping 

technology assessment. 

Commenters suggested that NHTSA’s 

NCAP should harmonize its lane 

keeping tests with Euro NCAP’s LSS test 

procedure. At the time of publication of 

the March 2022 RFC, Euro NCAP 

evaluated LDW systems using its LKA 

single-line test, which used a lateral 

velocity of 0.2 m/s to 0.5 m/s (0.7 ft./s 

to 1.6 ft./s), as previously noted.379

However, after the comment period for 

the March 2022 RFC closed, Euro NCAP 

introduced an updated protocol in 

which LKA single-line tests are 

conducted using lateral velocities of 0.2 

m/s to 0.6 m/s (0.7 ft./s to 2.0 ft./s), and 

the same procedure is used to evaluate 

LDW alerts from 0.6 m/s to 1.0 m/s (2.0 

ft./s to 3.3 ft./s) lateral velocity.380 It is 

unclear to the Agency whether these 

commenters desired harmonization 

based upon principle alone or whether 

commenters also believed that the 

specifications set at the time were 

appropriate. 

At this time, performing LDW 

assessments using higher lateral 

velocities (i.e., 0.7 m/s to 1.0 m/s (2.3 

ft./s to 3.3 ft./s)) would be more 

representative of intentional lane 

changes rather than unintentional 

drifting, which NHTSA’s LDW tests are 

designed to address. For intentional 

lane changes, LDW warnings do not 

serve to address a crash problem and 

may be viewed as a nuisance by drivers 

who then look to disable the LDW 

system. Given this possibility, the 

Agency will assess LDW alert 

functionality from 0.2 m/s to 0.6 m/s 

(0.7 ft./s to 2.0 ft./s) in NCAP. These 

same lateral velocities 0.2 m/s to 0.6 m/ 

s (0.7 ft./s to 2.0 ft./s) will also be used 

for NCAP’s LKA assessments. Note that 

NHTSA’s current LDW protocol 

specifies an allowable lateral velocity 

range of 0.1 m/s to 0.6 m/s; thus, the 

chosen lateral velocity range has already 

been in use to assess LDW performance. 

Since NHTSA’s chosen LKA and LDW 

test specifications (i.e., test scenarios, 

SV speeds, lateral velocities, etc.) are 

identical and LDW and LKA are meant 

to work together as a system, the Agency 

has chosen to evaluate LDW 

functionality during LKA testing. 

Assessing both technologies during the 

same test will promote efficiency, as 

IDIADA, TRC, and GM suggested, and 

reduce test burden on both NHTSA and 

manufacturers. It should additionally 

prompt expanded fleet coverage for LKA 

technology, as Aptiv asserted, and allow 

dual system optimization, as GM 

contended. In that vein, NHTSA expects 

that integrating LDW and LKA protocols 

will lead to a reduction in nuisance 

alerts. 

HATCI’s comment regarding the 

applicability of Euro NCAP’s protocol to 

the U.S market due to similar safety 

need is sound overall. That said, 

NHTSA also agrees with Tesla and Auto 

Innovators that BSW/BSI and LDW/LKA 

should be evaluated separately since the 

Agency’s desire is to address intended 

and unintended lane changes 

separately. Euro NCAP evaluates BSW 

(called ‘‘Blind Spot Monitoring’’, or 


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96048 Federal Register / Vol. 89, No. 232 / Tuesday, December 3, 2024 / Notices 

381European New Car Assessment Programme 

(Euro NCAP) (December 2023), Test Protocol—Lane 

Support Systems, Version 4.3. 

382https://crashstats.nhtsa.dot.gov/Api/Public/ 

ViewPublication/813298. 

BSM) and BSI using its Emergency Lane 

Keeping (ELK) Overtaking Vehicle 

scenario within its LSS protocol. For the 

Overtaking Vehicle test, lane keeping 

performance is evaluated using lateral 

velocities from 0.5 m/s to 0.7 m/s (1.6 

ft./s to 2.0 ft./s), a path containing a 

smaller radius of curvature (800 m, or 

2,625.0 ft.), and engagement of the turn 

signal. These requirements are designed 

to simulate conditions for an intentional 

lane change. 

Because the Agency will assess LKA 

and LDW as a system, if a vehicle fails 

to adequately intervene using LKA 

during a lane departure, the Agency will 

not conduct further evaluation with the 

intent to provide the vehicle LDW credit 

only, as some commenters requested. 

NHTSA also will not separately evaluate 

LDW systems on vehicles that do not 

offer LKA as part of this NCAP update. 

These vehicles will not receive lane 

keeping technology credit for meeting 

NHTSA-approved performance metrics 

and the Agency will not report the 

presence of LDW on its website. These 

decisions are similar to those which the 

Agency has made for FCW and AEB. 

The Agency reasons this NCAP update 

is an opportunity to increase 

performance requirements for new 

vehicles to gain lane keeping technology 

credit to inform consumer decisions, 

and it is now most appropriate to 

highlight the performance of LKA 

systems, not LDW, given the greater 

safety gains that active technology may 

offer. Maintaining the current LDW 

protocol, even for a transitional period 

of time, as FCA requested, would not 

accomplish this goal. Having said this, 

the Agency does not want to discount 

the importance of the LDW alert to 

passing lane keeping scores. LKA can 

provide the necessary steering 

correction to prevent a roadway 

departure; however, for a distracted or 

inattentive driver, the LDW alert may 

still be necessary to ensure driver reengagement. As will be detailed in a 

later section, a vehicle that fails to issue 

an LDW alert that conforms to NHTSA’s 

requirements will not receive credit for 

lane keeping technology, regardless of 

whether the vehicle’s LKA system 

provided acceptable intervention. 

Furthermore, as will be discussed later, 

while an LKA intervention will suffice 

as an LDW alert component, it will not 

be sufficient to satisfy all LDW alert 

requirements. As such, vehicles will not 

automatically receive LDW credit for a 

passing LKA intervention, as several 

commenters requested. 

3. Lane Marking Configurations 

Euro NCAP’s LSS protocol specifies a 

single lane line to evaluate LKA system 

performance.381 Citing the possibility 

that certain LKA systems may require 

the presence of lane lines on either side 

of the vehicle’s travel lane before they 

can be enabled, the Agency sought 

comment on whether it should require 

the use of a single lane line or two lane 

lines on the test surface in its final LKA 

test procedure. 

Summary of Comments 

Many commenters favored adopting a 

test procedure featuring one lane line, 

while several others supported adoption 

of two lane lines. 

Adopt a Single Lane Line 

Those in favor of a single lane line 

included Aptiv, Intel, AASHTO, ASC, 

ZF Group, HATCI, Honda, Auto 

Innovators, Bosch, and Tesla. AASHTO 

stated that testing with a single lane line 

would best mimic real-world 

conditions, as oftentimes only one line 

is visible, even on two lane roads, due 

to wear and tear, snow, etc. Bosch 

provided similar comments, stating that 

center road lines are often not 

detectable, particularly on rural roads, 

and recommended using one lane line 

to assess LKA performance to 

‘‘maximize LKS system availability’’ 

under such conditions. In its comments, 

ASC additionally mentioned that testing 

with a single lane line will encourage 

systems to operate in situations where 

only one line is present. Similarly, 

Honda opined that testing with a single 

lane line would incentivize systems to 

perform better on a greater number of 

roadway conditions and prevent lane 

departures when only one lane line is 

detected. HATCI, ASC, and Auto 

Innovators recommended adopting a 

single lane for U.S. NCAP testing to 

harmonize with Euro NCAP’s LSS 

protocol. Similarly, ZF Group 

recommended adopting a single lane 

line to ‘‘promote uniformity.’’ 

Adopt Two Lane Lines 

AAA and GM recommended that 

NHTSA adopt two lane lines rather than 

one in its LKA test procedure to best 

replicate real-world roadways. BMW, 

FCA, and TRC similarly recommended 

utilizing two lane lines to evaluate 

system performance because two-line 

lanes are more common on public roads 

in the U.S. In fact, FCA remarked 

(contrary to Auto Innovators) that roads 

having single lane lines are ‘‘rare’’ in 

this country compared to others. TRC 

also added that selecting a two-line lane 

marking configuration would permit 

more testing locations. 

Incorporate Both One Lane Line and 

Two Lane Lines 

Two commenters, CAS and Rivian, 

stated that the Agency should 

incorporate assessments for both one 

and two lane lines into NHTSA’s LKA 

test procedure, since both line formats 

are present on U.S. roads. Rivian 

suggested that NHTSA should reward 

systems that perform well for both lane 

line types with higher scores. 

Other Comments 

Honda acknowledged that two lane 

lines may be required to initialize an 

LKA system but assumed the Agency 

was referring to the ‘‘operation design 

domain for LKS systems’’ in its 

reference to ‘‘before they can be 

enabled,’’ and not an initialization 

process. The automaker asked that the 

Agency clarify the meaning of the 

referenced statement. Auto Innovators 

also referenced the need to drive a 

vehicle between two lane lines in some 

instances to assure system initialization 

prior to testing with one lane line. The 

commenter, along with Tesla, generally 

supported harmonization with Euro 

NCAP LSS protocols. However, Tesla 

also mentioned that if NHTSA were to 

adopt two lane lines to address 

evaluations of LKA systems that require 

two lines to be enabled, the Agency 

should evaluate how a system reacts to 

crossing only the near side lane line as 

well as both lane lines and modify 

passing criteria and points 

appropriately. Tesla further asserted 

that the far side lane line should trigger 

the LKA system, which in turn should 

reduce false-positive and true-negative 

LKA system interventions in the real 

world. 

The Advocates stated that NHTSA 

should conduct an analysis of road edge 

lines across states and correlate this 

information with crash data before 

deciding to incorporate one lane line 

type or another into its LKA test 

procedure. Citing NHTSA data that 

showed 7,424 fatalities occurred on 

rural local/collector roads in 2021 (i.e., 

17 percent of all fatalities),382 the group 

surmised that a large number of crashes 

may be occurring on roads having only 

a dashed or solid center line. The 

Advocates suggested that NHTSA 

provide data to show whether testing 

with one or two lane lines is more 

demanding on LKA systems and 


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383 23 CFR 655, Subpart F. 

384 Manual on Uniform Traffic Control Devices for 

Streets and Highways, 11th Edition. U.S. 

Department of Transportation, Federal Highway 

Administration. December 2023. See Section 3A.05. 

385 Manual on Uniform Traffic Control Devices for 

Streets and Highways, 11th Edition. U.S. 

Department of Transportation, Federal Highway 

Administration. December 2023. See Section 3A.06. 386 Manual on Uniform Traffic Control Devices for 

Streets and Highways, 11th Edition. U.S. 

Department of Transportation, Federal Highway 

Administration. December 2023. See Section 3B.14. 

387Euro NCAP’s ELK Solid Line tests utilize only 

dashed white and solid white lane lines. 

388European New Car Assessment Programme 

(Euro NCAP) (December 2023), Test Protocol—Lane 

Support Systems, Version 4.3. See Section 7.2.4.2. 

whether one lane marking format better 

exposes system deficiencies. 

Finally, regarding lane marking 

specifications themselves, Toyota and 

Auto Innovators commented that lane 

marking length should be specified 

since it serves as a ‘‘recognition process 

for the system.’’ The entities 

recommended a minimum lane marking 

length of 300 m (984 ft.). Aptiv and ASC 

recommended that the Agency align 

lane widths used during LDW and LKA 

testing (currently 3.6 to 4.3 m (12 to 14 

ft.)) with U.S. lane width standards, 

which specify a lane width of 2.7 to 3.6 

m (9 to 12 ft.). Accordingly, the 

companies requested that NHTSA 

specify a maximum lane width of 3.7 m 

(12 ft.), which they stated would also 

better harmonize with Euro NCAP, 

which specifies a lane width of 3.5 to 

3.7 m (11.5 to 12 ft.). ASC also added 

that NHTSA should always reference 

the latest Manual on Uniform Traffic 

Control Devices (MUTCD) published by 

the Federal Highway Administration 

(FHWA) for lane marking and road 

configurations.383

Response to Comments and Agency 

Decisions 

For the purposes of evaluating a 

vehicle’s LDW alert sensitivity and 

primary LKA intervention capabilities, 

NHTSA’s testing will include the use of 

(1) a single solid white lane line, (2) a 

single dashed yellow lane line, or (3) 

Botts’ Dots on either the right or left side 

of the vehicle’s travel lane, depending 

on testing direction. These lane line 

colors and types are currently specified 

in NCAP’s LDW test procedure. These 

lane line colors/types remain acceptable 

for NHTSA’s testing because, per the 

FHWA’s MUTCD, yellow lane markings 

for longitudinal lines are permitted to 

delineate, among other things: (1) the 

separation of traffic traveling in 

opposite directions and (2) the left-hand 

edge of the roadways of divided 

highways and one-way streets or ramps. 

White markings for longitudinal lines 

are permitted to delineate: (1) the 

separation of traffic flow in the same 

direction or (2) the right-hand edge of 

the roadway.384 The MUTCD also states 

that a solid line shall be used to 

discourage or prohibit crossing 

(depending on the specific application) 

and a broken line shall be used to 

indicate a permissive condition.385

Further, raised pavement markers, such 

as Botts’ Dots, may serve as a substitute 

for pavement markings, as long as they 

simulate that pattern of the markings for 

which they substitute.386 Euro NCAP’s 

LSS test protocol specifies the use of 

either a solid or dashed line present in 

the direction of departure for LKA and 

LDW tests. 

Adopting the single-line approach for 

these evaluations should ensure that 

LDW and LKA systems can operate in 

a greater number of real-world 

situations. Though roadways are 

typically designed to contain two lane 

markings denoting left and right sides of 

the lane, road conditions may vary 

greatly. The Agency sees merit in 

several commenters’ suggestions that 

sometimes only a single line may be 

visible due to road wear or 

precipitation. By isolating the test 

conditions to a single lane line on either 

the right- or left-hand side of the SV, the 

test will assess whether the vehicle can 

detect the lane line independent of its 

other surroundings, which may vary in 

an infinite number of ways. Since a realworld vehicle may not have a second 

lane line to confirm that a lane 

departure is occurring, a single-line test 

should improve sensing such that 

vehicles no longer require the second 

lane line for LDW or LKA to reliably 

function. Furthermore, the use of a 

single lane line for the Agency’s tests 

should not restrict manufacturers from 

using a second lane line, when 

available, to inform a vehicle’s LKA 

system and further improve 

performance in the myriad of scenarios 

a driver will encounter in the real 

world. 

Given the reasons above, systems 

which only require the presence of one 

lane line to function are preferable to 

those which require two (i.e., one on 

each side of the vehicle); however, 

certain complications arise when 

evaluating LKA system performance 

using only one lane line. NHTSA 

acknowledges concern exists regarding 

secondary lane departures that may 

occur after an LKA intervention. In 

these cases, the vehicle steers back into 

the lane but then overcorrects and 

departs the lane on the opposite side of 

the original intervention. These cases 

cannot be accounted for during tests in 

which there is only one lane line. 

Therefore, the Agency will also perform 

additional testing with two lane lines to 

evaluate a vehicle’s ability to properly 

correct the vehicle’s heading after the 

initial intervention. As detailed in a 

subsequent section, the lane markings 

for this test series will consist of (1) a 

right solid white line and a left dashed 

white line, meant to simulate an SV 

traveling on a multi-lane road in the 

rightmost lane, and (2) a right dashed 

white line and a left solid yellow line, 

meant to simulate an SV travelling on a 

multi-lane road in the leftmost lane. 

These lane marking configurations are 

similar to those used 387 in Euro NCAP’s 

Emergency Lane Keeping (ELK) Solid 

Line test scenarios.388 However, unlike 

in Euro NCAP’s testing, for each dual 

line configuration, assessments will be 

made for both left and right departures 

(i.e., across both dashed and solid lane 

lines). 

Thus, LKA testing will occur with 

both styles of lane markings: single lane 

lines on either the right or left side of 

the travel lane and two lane lines with 

one on each side of the vehicle. Vehicles 

traveling in real-world situations will 

likely encounter both scenarios, as CAS 

and Rivian remarked. By performing 

both single line and dual line 

assessments, NHTSA expects to ensure 

robust everyday performance. Systems 

will not be able to rely on the use of the 

second lane line for normal operation, 

but performance that is confounded by 

a second lane line should be evident. 

To address concerns regarding 

initialization of LDW and LKA systems, 

NHTSA plans to accept information 

from vehicle manufacturers detailing 

the procedures necessary to properly 

initialize systems for use. This 

information is already being collected 

prior to NCAP’s current ADAS testing of 

new vehicle models. Further, the 

Agency is aware of cases where the 

vehicle must be driven a minimum 

number of miles in normal use 

conditions prior to assessment of ADAS 

technologies. 

Regarding other characteristics of lane 

markings, as with the BSW and BSI 

testing included in this final notice, 

NHTSA has decided to adopt a 3.5 m to 

3.7 m (11.5 ft. to 12 ft.) lane width 

specification for its LDW and LKA tests 

for this NCAP update. In doing so, the 

Agency will align with Euro NCAP’s 

LSS procedure and will more closely 

reflect AASHTO standards. The Agency 

will also impose a requirement that lane 

line markings extend for a minimum of 

300 m (984 ft.), as Toyota and Auto 

Innovators requested. This lane line 


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96050 Federal Register / Vol. 89, No. 232 / Tuesday, December 3, 2024 / Notices 

389Winslow, J. (2017, May 19), Botts’ Dots, after 

a half-century, will disappear from freeways, 

highways, The Orange County Register, https://

www.ocregister.com/2017/05/19/botts-dots-after-ahalf-century-will-disappear-from-freewayshighways/. 

390https://dot.ca.gov/programs/public-affairs/ 

faqs. 

391 Manual on Uniform Traffic Control Devices for 

Streets and Highways, 11th Edition. U.S. 

Department of Transportation, Federal Highway 

Administration. December 2023. See Section 3B.17. 

392 Manual on Uniform Traffic Control Devices for 

Streets and Highways, 11th Edition. U.S. 

Department of Transportation, Federal Highway 

Administration. December 2023. See Section 5B.02. 

length should be sufficient for LDW and 

LKA systems to interpret lane 

departures appropriately during the test 

validity period and accommodate 

secondary departure assessments. 

Finally, the Agency notes that it 

included the MUTCD as a reference for 

lane markings in both the LDW and 

draft LKA test procedures and has 

included it in the test procedures 

prepared for this NCAP update. 

4. Botts’ Dots/Raised Pavement Markers 

Test Condition 

In its March 2022 RFC notice, the 

Agency proposed to remove the Botts’ 

Dots (i.e., raised pavement marker) test 

scenario from the current LDW test. 

This decision stemmed from the fact 

that information available to NHTSA 

suggested that the lane markers were 

being removed from use in California 389

and a preliminary assumption that the 

traditional dashed and solid lane 

marking tests may be sufficient to 

evaluate vehicle performance. 

Summary of Comments 

In Favor of Removal 

Those in favor of removing the Botts’ 

Dots test scenario from the Agency’s 

LDW test procedure included BMW, 

GM, HATCI, Honda, Auto Innovators, 

Bosch, TRC, MEMA, ASC, FCA, 

IDIADA, Intel, Tesla, and two 

individuals. Both HATCI and TRC cited 

reduced test burden as reasons to 

remove the Botts’ Dots test condition. 

ASC, FCA, Intel, Tesla, and a public 

commenter all cited discontinued use in 

California as a reason for removal. 

Similarly, IDIADA mentioned that the 

Botts’ Dots condition is becoming a 

‘‘niche scenario with low relevancy’’ 

and Honda stated that there is no longer 

a safety need. TRC suggested replacing 

the Botts’ Dots test condition with a 

road edge detection test because it is a 

more common real-world condition and 

possible at most testing laboratories. 

Oppose Removal 

Although the overwhelming majority 

of commenters were in favor of 

removing the Botts’ Dots test condition 

from the Agency’s LKA test procedure, 

Rivian asserted that this test scenario 

was still a necessary assessment for 

LDW systems. The manufacturer 

contended that most vehicles would 

likely encounter Botts’ Dots at some 

point since lane markings across the 

U.S. are not uniform. Rivian also stated 

that manufacturers may not design for 

this test condition if it was not part of 

NHTSA’s test protocol which, in turn, 

would lead to reduced system 

effectiveness and overall safety. Along 

these lines, Advocates recommended 

that NHTSA provide information on the 

prevalence of Botts’ Dots in states other 

than California and the length of time 

before Botts’ Dots would be replaced 

before the Agency can be assured that 

removing them would not be a 

detriment to safety. 

Response to Comments and Agency 

Decisions 

NHTSA has decided not to remove 

the raised pavement markers test 

scenario, which utilizes Botts’ Dots, 

from its LDW/LKA test procedure for 

this NCAP upgrade. The Agency agrees 

with Rivian that it is possible vehicles 

may encounter Botts’ Dots or other 

raised pavement markers in lieu of 

painted lane lines at some point during 

their useful life. In fact, more recent 

information from Caltrans, which 

manages over 50,000 miles of 

California’s highway and freeway lanes, 

suggests the organization has no 

intention at this time of removing Botts’ 

Dots from California’s roadways.390 The 

Agency also recognizes that Botts’ Dots 

or similar raised pavement markers are 

utilized in other states as well. The 

MUTCD provides guidelines for raised 

pavement markers as a substitute for 

broken line, solid line, and dotted lane 

line markings.391 Given this, and the 

fact that such pavement markers are 

unique compared to painted lane 

markings, NHTSA agrees with Rivian 

that retaining Botts’ Dots assessments 

for NCAP’s LDW/LKA assessments will 

best assure overall LDW/LKA system 

effectiveness and safety. The Agency 

reasons the slight increase in test 

burden such testing will generate is 

worth the assurance that vehicles will 

react appropriately if they encounter 

similar lane markings. 

Having said this, NHTSA also 

acknowledges FHWA’s most recent 

guidance to agencies in its December 

2023 MUTCD that discourages the use 

of raised pavement markers as a 

substitute for lane markings when 

designing roadways for automated 

vehicles.392 As such, the Agency will 

monitor changes made to roadway lane 

demarcations to better accommodate 

forthcoming vehicle designs and may 

revisit the necessity of conducting test 

scenarios using Botts’ Dots or other 

raised pavement markers in the future. 

5. Addressing Secondary Departures 

The Agency explained in its March 

2022 RFC notice that it would like to be 

assured that, when a vehicle is 

redirected after an initial LKA system 

intervention, if the vehicle then 

approaches the lane marker on the side 

not tested, the LKA will again engage to 

prevent a secondary lane departure by 

not exceeding the same maximum 

excursion limit established for the first 

side. 

To prevent secondary lane departures, 

NHTSA sought comments on whether it 

should consider modifying Euro NCAP’s 

LKA evaluation criteria to be consistent 

with language developed for NHTSA’s 

BSI test procedure to prevent this issue. 

NHTSA’s BSI test procedure states that 

the SV’s BSI intervention shall not 

cause the vehicle to travel more than 0.3 

m (1 ft.) beyond the inboard edge of the 

lane line separating the SV’s travel lane 

from the lane adjacent and to the right 

of it within the validity period. To 

assess whether this occurs, a second 

lane line is required; however, only one 

lane line is specified in the Euro NCAP 

LSS protocol for LKA testing. The 

Agency questioned whether the 

introduction of a second lane line 

would have the potential to confound 

LKA testing. 

Summary of Comments 

Agree With Adding Assessment for 

Secondary Lane Departures 

The majority of commenters 

(Advocates, ASC, BMW, CAS, Honda, 

Intel, Rivian, Tesla, TRC, and ZF Group) 

expressed support for NHTSA 

modifying the LKA test procedure to 

ensure tested LKA systems intervene a 

second time to prevent secondary lane 

departures. 

BMW did not comment that there was 

risk to adding a secondary lane line, 

since LKA systems are designed to align 

with the lane marking(s) after an 

intervention, but the commenter also 

recommended that the Agency adopt a 

two-line marked lane since it is most 

common. Along these lines, Intel 

recommended that, in adding a second 

lane line, NHTSA should ensure that 

the created lane represents real-world 

roadways and lane markings. Like 

BMW, ASC, Rivian, Tesla, and ZF 

Group reasoned that the addition of a 

second lane line should not adversely 

affect LKA performance. That said, ASC 


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393Cicchino & Zuby, 2017. Prevalence of driver 

physical factors leading to unintentional lane 

departure crashes. Traffic Injury Prevention, 18(5), 

481–487. 

asserted that it was reasonable to expect 

that LKA systems would prevent 

secondary departures regardless, and ZF 

Group similarly mentioned that the 

second lane line should simply trigger 

an LKA intervention. Rivian was 

supportive of adopting a test scenario 

that allowed the SV to ‘ping-pong’ 

between lane lines two or more times to 

assess system functionality. CAS 

asserted that whether there is a lane line 

or not, the LKA system should keep the 

vehicle in the lane after an initial LKA 

intervention, and ensuring this 

functionality is important to consumers. 

While CAS maintained that, for safety 

reasons, no amount of excursion over 

the other lane line was acceptable for a 

secondary lane departure, Honda and 

ASC agreed that the Agency should 

adopt the same maximum excursion 

limits for primary and secondary lane 

departures. Honda saw no point in 

deviating since the current maximum 

limit is based on real-world data. The 

automaker also requested that the 

Agency adopt the appropriate roadway 

widths (based on real-world roadways) 

for the tested speeds if NHTSA adopts 

a second lane line. The commenter 

asserted that adopting a lane width that 

is too narrow for the speeds tested may 

cause inadvertent LKA system 

activation for the opposite lane line. 

Similarly, Intel remarked that a dually 

marked lane must be greater than a 

certain width so that the LKA system 

will have sufficient margin to not 

exceed the maximum excursion limit. 

Advocates also supported evaluating 

secondary lane departures but requested 

that if adding the second lane line 

reduces the stringency of lane or road 

departure tests, NHTSA should conduct 

the tests to assess prevention of 

secondary lane departures separately. 

Rivian suggested that the Agency reduce 

ratings for systems that struggle to 

prevent secondary lane departures. TRC 

preferred that LKA and BSI protocols 

have consistent language but also 

commented that secondary lane 

departure evaluations require increased 

space for testing. 

Do Not Agree With Adding Assessment 

for Secondary Lane Departures 

Some commenters did not agree with 

modifying the LKA test procedure to 

ensure systems intervene to prevent 

secondary lane/road departures. Several 

of these commenters relayed that such 

an assessment was not necessary (Bosch 

and Toyota) or not warranted (Auto 

Innovators and GM). Bosch indicated 

that if the system avoids a departure on 

one side of the lane, and separately 

when tested for the other side of the 

lane, then it should prevent a secondary 

departure. FCA maintained that each 

lane departure intervention is a single 

event that ends after the intervention is 

complete. As such, the automaker 

considered a secondary lane departure 

to be a new lane departure event. 

Toyota and Auto Innovators stated 

that since LKA is designed to prevent or 

mitigate lane or roadway departures due 

to driver inattentiveness, drowsiness, 

etc., secondary departures should not 

serve as a basis to assess system 

performance. Likewise, GM commented 

that the first intervention serves to grab 

the driver’s attention so that the driver 

intervenes to prevent a secondary 

departure. Auto Innovators and GM 

added that a driver-monitoring system 

may be necessary for those drivers who 

are not attentive after an initial LKA 

intervention, especially for those who 

may be misusing the system (e.g., 

driving with no hands on the wheel) 

and who purposely allow their vehicle 

to ‘ping-pong’ between lane lines. Both 

groups further asserted that current 

systems are designed to re-center the 

vehicle in the lane after an intervention, 

not to direct the vehicle toward the 

opposite lane marker such that a 

secondary lane departure would occur. 

Along the lines of those comments 

from Auto Innovators and GM, IIHS 

expressed that it shares NHTSA’s 

concern about ramifications of LKA 

interventions because the group’s 

research 393 has shown that many of 

those drivers involved in lane departure 

crashes were sleeping or otherwise 

incapacitated (34 percent); had a nonincapacitating medical-issue, blood 

alcohol concentration (BAC) of 0.08 

percent or more, or physical factor that 

could impair their ability to safely 

control a vehicle (13 percent), such that 

they would be unlikely to regain control 

of the vehicle after an initial LKA 

intervention. Accordingly, the group 

encouraged NHTSA to add to NCAP 

technologies that could detect such a 

driver and intervene to safely stop their 

vehicle, or preferably pull their vehicle 

over on the side of the road. 

Response to Comments and Agency 

Decisions 

Given the comments received, the 

Agency has decided to incorporate 

additional LKA test scenarios that are 

comparable (though not identical) to 

Euro NCAP’s Emergency Lane Keeping 

(ELK) Solid Line test to address 

secondary lane departures. NHTSA 

agrees with ASC that it is a reasonable 

expectation that LKA systems should 

prevent secondary departures, and, as 

CAS suggested, ensuring that LKA 

systems keep a vehicle in the lane after 

an initial intervention is important to 

consumers. It is also imperative for 

safety. 

Unlike the Agency’s other LKA test 

scenarios, these secondary departure 

scenarios will utilize two lane lines to 

permit assessment of a secondary 

departure. Assessments will be made for 

two configurations—one simulating a 

vehicle travelling in the rightmost lane 

of a multi-lane road, with a solid white 

line to its right and dashed white line 

to its left, and the second simulating a 

vehicle travelling in the leftmost lane of 

a multi-lane road, with a solid yellow 

line to its left and a dashed white line 

to its right. Since these lane line 

combinations are common during realworld driving on multi-lane roads, they 

are appropriate for inclusion in 

NHTSA’s testing. Also, utilizing a 

dashed white line and solid yellow line 

for the secondary departure tests 

effectively complements the Agency’s 

dashed yellow and solid white single 

lane line tests, respectively. 

The Agency had expressed some 

concern in its March 2022 RFC notice 

that the addition of a second lane line 

in NCAP’s lane keeping tests may 

confound LKA performance and thus 

test results. At the time, however, the 

Agency did not take into consideration 

that Euro NCAP’s ELK Road Edge tests, 

which were/are performed similarly to 

their LKA tests, (and which the Agency 

is adopting for its LKA assessments), 

required a second lane line. 

Furthermore, Euro NCAP’s LSS protocol 

has since been updated to include a 

second lane line for the program’s ELK 

Solid Line tests, which will closely 

mirror the secondary departure tests 

adopted by NHTSA. As such, NHTSA 

now agrees with commenters that its 

initial concern was unwarranted. The 

Agency has not only adopted test 

parameters for the secondary departure 

test that align with Euro NCAP’s current 

ELK Solid Line test (with the exception 

of the addition of a solid yellow lane 

line), but it has also adopted lane width 

requirements for its LKA testing that 

match those utilized by Euro NCAP. 

Euro NCAP’s ability to successfully 

conduct the ELK Solid Line test 

demonstrates inherent practicality and 

should temper Honda’s (and NHTSA’s) 

previous concerns surrounding 

inadvertent LKA system activation 

caused by the opposite lane line. 

Furthermore, NHTSA has adopted lane 

marking length specifications to address 

commenter concerns regarding system 

lane recognition. The Agency has 


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394Specifically, LDW warning requirements 

specify a visual LDW alert and an auditory or haptic 

alert (which may be an LKA intervention) that must 

be issued within a tolerance that spans 0.75 m to 

–0.30 m (2.5 ft. to –1.0 ft.), and the visual alert must 

be issued prior to, or concurrent with, the LKA 

intervention. 

395Wiacek, C., Forkenbrock, G., Mynatt, M., & 

Shain, K. (2019), Applying lane keeping support 

test track performance to real-world crash data. 26th 

International Technical Conference for the 

Enhanced Safety of Vehicles, Eindhoven, 

Netherlands. Paper Number 19–0208. 

396A robotic steering controller was used to 

maximize the repeatability and minimize variability 

associated with manual steering inputs. 

397At the time of testing, an older version of Euro 

NCAP’s LSS test procedure stipulated a lane keep 

assist assessment criterion of 0.4 m (1.3 ft.) for the 

maximum excursion over the inside edge of the 

lane marking. European New Car Assessment 

Programme (Euro NCAP). See Assessment 

Protocol—Safety Assist, Version 7.0 (2015, 

November). 

398Wiacek, C., Forkenbrock, G., Mynatt, M., & 

Shain, K. (2019), Applying lane keeping support 

test track performance to real-world crash data. 26th 

International Technical Conference for the 

Enhanced Safety of Vehicles, Eindhoven, 

Netherlands. Paper Number 19–0208. 

399Reports for these tests can be found in the 

docket for this notice. 

conducted limited testing to observe 

secondary departures and concludes 

that such assessments are feasible, even 

considering TRC’s concerns about the 

space required for test conduct. The 

Agency will specify that vehicles 

achieve at minimum of 3 seconds of 

steady state speed before the lane 

departure is initiated to establish a 

baseline path from which the vehicle 

will deviate. However, to restrict the 

required space needed for testing, 

NHTSA will limit the test validity 

period to the first of the following 

events: (1) the point in time when the 

SV travels more than 0.3 m (1 ft.) 

beyond the inboard edge of the primary 

lane line separating the SV’s travel lane 

from the lane adjacent to it; (2) 5 

seconds after the SV has established a 

heading away from the primary lane 

line and is completely within its 

original travel lane; or (3) 1 second after 

the SV travels more than 0.3 m (1 ft.) 

beyond the inboard edge of the 

secondary lane line, where the primary 

line is the line the SV heading’s was 

initially directed towards and the 

secondary line is the line on the 

opposite side of the SV’s travel lane 

with respect to the primary line. The 

Agency’s testing has shown the track 

length required to fulfill these 

requirements is reasonable. 

Like the other LKA tests adopted for 

this NCAP update, the SV will be driven 

at 72 kph (44.7 mph) for the secondary 

departure tests, and the lateral velocity 

of the SV’s approach to the lane line 

will be increased from 0.2 to 0.6 m/s 

(0.7 to 2.0 ft./s) in 0.1 m/s (0.3 ft./s) 

increments. Acceptable LKA 

performance will be defined by the 

system’s ability to prevent the SV from 

crossing the inboard leading edge of the 

lane line by more than 0.3 m (1.0 ft.). 

This maximum lane line excursion limit 

will apply for both primary and 

secondary departures, as several 

commenters requested. NHTSA agrees 

with Honda that there is no need to 

deviate from the limit adopted for the 

initial departure, since as mentioned 

earlier, it has real-world practicality. If 

the system’s initial intervention satisfies 

the performance requirement, the test 

will continue to discern whether the 

vehicle’s subsequent movement will 

cause a second LKA intervention. If the 

LKA system once again satisfies the 

performance requirements for the 

second intervention or does not trigger 

vehicle movement that necessitates a 

second intervention (i.e., aligns the 

vehicle with the lane marking(s) after 

the initial intervention) within the 

validity period, the vehicle will receive 

passing results. Assessments will be 

performed for departures on both sides 

of the vehicle (i.e., left and right) and 

the same LDW warning requirements 

adopted for the Agency’s other LKA 

tests (which will be defined later) will 

apply.394

While NHTSA agrees in theory with 

Bosch that an LKA system that prevents 

a lane departure on one side should 

similarly prevent a lane departure on 

the opposite side such that evaluations 

for secondary departures should be 

unnecessary, the Agency has an 

obligation to the consumer to confirm 

Bosch’s assumption, particularly since, 

as will be discussed later, the Agency’s 

testing has shown that a vehicle’s 

response can vary based on departure 

direction and lane line type. It is 

NHTSA’s hope, however, that most 

systems are designed to re-center the 

vehicle in the lane after an intervention, 

as Auto Innovators and GM stated, and 

that systems exhibiting alternative 

performance will undergo design 

improvements conducive to lane 

centering. As such, the Agency will not 

end the test after the first lane departure 

event, as FCA suggested, but will 

instead continue to assess performance 

after the first intervention. 

NHTSA also sees merit in conducting 

testing to assess secondary departures 

despite commenters’ objections that the 

intent of LKA is for the initial 

intervention to grab the driver’s 

attention so that the driver intervenes to 

prevent a secondary departure. While 

the commenters’ perspective regarding 

the main purpose of LKA systems may 

be accurate, the Agency maintains that 

an inattentive or drowsy driver also 

would likely benefit from a secondary 

intervention, as the primary 

intervention may cause the driver to 

suddenly attempt to retake control, 

potentially overcorrecting for steering 

and/or braking and thus imparting 

additional safety risk. Further, although 

the Agency acknowledges commenters’ 

assertions that a driver monitoring 

system may aid an incapacitated driver, 

NHTSA is not considering evaluations 

for such technology as part of this effort. 

As will be discussed later in this notice, 

such systems may be considered for 

adoption in NCAP in the future at such 

time when the research has been 

completed and objective test procedures 

are available. 

6. Appropriate Lateral Velocities for 

LKA 

In its 2022 RFC notice, NHTSA cited 

research it had conducted on five model 

year 2017 vehicles to study the effect of 

increasing lateral velocity on LKA 

system performance.395 For this study, 

the Agency used a slightly modified and 

older version of Euro NCAP’s LSS test 

procedure than that discussed 

previously. Specifically, the Agency 

deviated from the Euro NCAP procedure 

and increased the lateral velocity of the 

SV’s approach towards the lane line 

from 0.1 m/s to 1.0 m/s in 0.1 m/s 

increments (0.3 ft./s to 3.3 ft./s in 0.3 ft./ 

s increments).396 LKA performance was 

considered acceptable in instances 

where the SV did not cross the inboard 

leading edge of the lane line by more 

than 0.4 m (1.3 ft.).397 398

An analysis of the five tested vehicles 

identified performance differences 

between the vehicles depending on the 

lateral velocity used during the test. 

Some vehicles only provided a steering 

response at lower lateral velocities 

while others continued to produce a 

steering input as the lateral velocity 

increased. As will be discussed further 

in a subsequent section, the maximum 

excursion over the lane marking after an 

LKA activation was also found to be 

inconsistent, particularly as lateral 

velocity increased. 

Additional LKA tests were run on six 

model year 2019 vehicles.399 For each 

model, vehicle response to solid white 

and dashed white lines was assessed for 

both left and right departure directions. 

The same lateral velocities as those used 

in the model year 2017 vehicle tests 

mentioned previously were used in the 

model year 2019 testing. Findings from 

this testing were similar. 

At the time of publication of the 

March 2022 RFC, to represent 


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400European New Car Assessment Programme 

(Euro NCAP) (July 2019), Test Protocol—Lane 

Support Systems, Version 3.0.2. 

unintended lane departures (i.e., not an 

intended lane change), Euro NCAP’s 

LSS protocol specified use of a range of 

lateral velocities from 0.2 to 0.5 m/s (0.7 

to 1.6 ft./s) for its LKA and Road Edge 

recovery tests and a range of lateral 

velocities from 0.3 to 0.6 m/s (1.0 to 2.0 

ft./s) for its Emergency Lane Keeping— 

Oncoming vehicle and Emergency Lane 

Keeping—Overtaking vehicle tests.400

Given the Agency’s findings from its 

research testing, NHTSA requested 

comment on whether it should consider 

adopting a combination of the two 

lateral velocity ranges specified by Euro 

NCAP for unintended lane departures, 

specifically 0.2 to 0.6 m/s (0.7 to 2.0 ft./ 

s), for inclusion in NHTSA’s LKA 

evaluation to encourage the most robust 

LKA system performance. 

Summary of Comments 

In support of combining and/or 

aligning tested lateral velocities to 0.2 to 

0.6 m/s (0.7 to 2.0 ft./s) were Auto 

Innovators, Honda, ASC, BMW, FCA, 

HATCI, Intel, and Bosch. Several of 

these commenters focused on 

harmonization, while others mentioned 

system robustness. 

Combine for Harmonization 

Honda asserted that the lateral 

velocities should be consistent when 

test procedures are designed to 

represent the same pre-crash scenario. 

As such, the manufacturer supported 

combining the two ranges of lateral 

velocities. Similarly, FCA commented 

that aligning with the Euro NCAP 

procedures and combining the lateral 

velocity range would minimize test 

burden and adequately gauge 

performance. GM also supported the 

proposal to adopt a lateral velocity 

range of 0.2 to 0.6 m/s (0.7 to 2.0 ft./s) 

to ‘‘simplify testing, provide more 

consistency in testing, and better align 

with Euro NCAP and limits proposed in 

SAE J3240 Work In Progress (WIP). 

HATCI supported combining the lateral 

velocities to harmonize with Euro NCAP 

test procedures, which they considered 

‘‘widely accepted’’ and ‘‘largely 

representative of the field.’’ 

However, Advocates stated that 

NHTSA had not provided enough data 

or justification to support adoption of 

the range of lateral velocities specified 

in the Euro NCAP test procedures. They 

asked that the Agency conduct an 

analysis using data from event data 

recorders, NHTSA’s crash 

reconstruction databases, naturalistic 

driving studies, etc. to justify that the 

proposed range is representative of U.S. 

crashes. 

Combine To Ensure System Robustness 

Intel recommended combining the 

lateral velocity ranges to encourage 

robust LKA performance, since they 

asserted that NCAP serves to ‘‘raise the 

bar’’ and incentivize adoption of the 

most advanced systems. At a minimum, 

however, the company recommended 

that NHTSA harmonize with Euro 

NCAP’s LKA and Road Edge tests. ASC, 

which also favored combining the 

lateral velocity ranges, commented that 

testing at higher lateral velocities should 

improve system robustness and, in turn, 

safety and consumer acceptance. Auto 

Innovators similarly commented that 

higher lateral velocities will 

differentiate more robust system designs 

since respective testing will be more 

difficult to meet. However, the group 

cautioned that 0.6 m/s should be the 

upper limit used for testing, as 

unintended lane departures may be 

more difficult to distinguish at higher 

lateral velocities. Finally, CAS 

suggested that the Agency look into 

combining the two unintended 

departure ranges prescribed by Euro 

NCAP, as this should ‘‘provide an 

additional safety margin.’’ However, like 

Advocates, CAS also recommended that 

NHTSA conduct additional research to 

determine whether Euro NCAP’s 

protocol best aligns with the crash 

problem in the U.S. 

Other Recommendations 

ZF Group didn’t agree that NHTSA 

should simply combine the lateral 

velocity ranges. They stated that ‘‘both 

Euro NCAP tests referenced were 

carefully developed and address 

different scenarios.’’ Therefore, the 

group opined that the Agency should 

align with Euro NCAP’s protocol (to the 

greatest extent possible) for both tests. 

In a similar vein, Rivian commented 

that the 0.6 m/s (2.0 ft./s) lateral velocity 

is appropriate for oncoming vehicle and 

overtaking vehicle tests because they are 

designed to assess systems that offer 

increased warning and assist thresholds; 

however, using a 0.6 m/s (2.0 ft./s) 

lateral velocity to assess vehicles in a 

traditional LKA test where this 

extended capability is not necessary 

may increase false positives and reduce 

usage of LKA systems. The 

manufacturer added that systems 

capable of performing well in oncoming 

vehicle and overtaking vehicle tests 

should receive higher scores. 

Response to Comments and Agency 

Decisions 

As noted at the beginning of this 

section, when the Agency sought 

comment on this specification, there 

were two ranges of lateral velocities 

being used in the Euro NCAP suite of 

ELK, LKA, and Road Edge tests: 0.2 m/ 

s to 0.5 m/s (0.7 ft./s to 1.6 ft./s) and 0.3 

m/s to 0.6 m/s (1.0 ft./s to 2.0 ft./s). The 

Agency proposed to adopt a singular 

range which combined the two Euro 

NCAP ranges for its LKA testing 

protocol. Newer versions of Euro 

NCAP’s LSS procedure, dated 

November 2022 and December 2023, 

incorporate this combined range for the 

program’s LKA and ELK tests. In 

tandem with the many comments 

received regarding harmonization, Euro 

NCAP’s acceptance of this new range 

further bolsters support for the 

combined lateral velocity range 

proposed. Thus, NHTSA will adopt the 

combined range of 0.2 m/s to 0.6 m/s 

(0.7 ft./s to 2.0 ft./s) for SV lateral 

velocities assessed in its LDW/LKA 

tests, with lateral velocities tested in 

increasing increments of 0.1 m/s (0.3 ft./ 

s) to ensure robustness throughout the 

test range. 

NHTSA notes that harmonization 

with Euro NCAP for this test 

specification is desired not only by the 

Agency but by many commenters as 

well. Reasons cited included minimized 

test burden, simplified testing, and use 

of widely accepted parameters. 

Manufacturers and test laboratories 

should be familiar with performing 

LKA-style testing using this range of 

lateral velocities. Further, a move to 

align test procedures to the most 

reasonable extent possible satisfies a 

part of the BIL, as mentioned 

throughout this notice. 

Beyond harmonization, as Intel, ASC, 

and Auto Innovators noted, a wider 

range of lateral velocities will be more 

difficult to meet and should encourage 

manufacturers to design more robust 

systems for their vehicle models. 

NHTSA concludes ZF Group’s concern 

regarding the differences between test 

types in Euro NCAP is no longer 

applicable since Euro NCAP has moved 

toward the 0.2 m/s to 0.6 m/s (0.7 ft./ 

s to 2.0 ft./s) lateral velocity range for all 

scenarios that will be implemented in 

NCAP. Also, the Agency notes that both 

lateral velocity ranges used previously 

in Euro NCAP were initially intended to 

approximate lateral velocities 

experienced during unintended lane 

departures, lending credence to Honda’s 

comment regarding alignment of test 

specifications under similar scenarios. 

NHTSA does not anticipate a greater 


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401For this testing, one trial was conducted per 

test condition (i.e., combination of lane line type, 

lateral velocity, and departure direction). 

402Tanaka, S., Mochida, T., Aga, M., & Tajima, J. 

(2012, April 16). Benefit Estimation of a Lane 

Departure Warning System using ASSTREET. SAE 

Int. J. Passeng. Cars—Electron. Electr. Syst. 

5(1):133–145, 2012, https://doi.org/10.4271/2012- 

01-0289. 

403For the Agency’s research, the lateral velocity 

of the SV’s approach towards the lane line was 

increased from 0.1 m/s to 1.0 m/s in 0.1 m/s 

increments (0.3 ft./s to 3.3 ft./s in 0.3 ft./s 

increments). 

404At the time of testing, an older version of Euro 

NCAP’s LSS test procedure stipulated a lane keep 

assist assessment criterion of 0.4 m (1.3 ft.) for the 

maximum excursion over the inside edge of the 

lane marking. European New Car Assessment 

Programme (Euro NCAP). See Assessment 

Protocol—Safety Assist, Version 7.0 (2015, 

November). 

405Wiacek, C., Forkenbrock, G., Mynatt, M., & 

Shain, K. (2019), Applying lane keeping support 

test track performance to real-world crash data. 26th 

International Technical Conference for the 

Enhanced Safety of Vehicles, Eindhoven, 

Netherlands. Paper Number 19–0208. 

number of false positive or nuisance 

activation events from the use of a 0.6 

m/s (2.0 ft./s) lateral velocity, as Rivian 

asserted, given that it is currently the 

upper tolerance for LDW testing and has 

been implemented in Euro NCAP’s test 

protocol and the test procedure does not 

simulate a driver actively steering but 

specifies a trajectory. 

Data gathered by NHTSA for both 

model year 2017 and 2019 vehicles 

shows that most vehicles failed to 

adequately intervene during the 0.5 m/ 

s (1.6 ft./s) and higher lateral velocity 

tests; this held true for both solid and 

dashed line assessments.401 Three 

vehicles failed to offer any LKA 

intervention at least once (i.e., for either 

left- or right-side departures) at 0.5 or 

0.6 m/s (1.6 ft./s or 2.0 ft./s). Overall, 

four of the 11 vehicles did not offer any 

intervention at least once in testing from 

0.2 m/s to 0.6 m/s (0.7 ft./s to 2.0 ft./s). 

Notwithstanding, the majority of the 11 

vehicles did offer some level of lane 

correction. Notably, one vehicle of the 

11 tested successfully prevented 

excessive excursion (greater than 0.3 m, 

or 1.0 ft.) in each of the proposed lateral 

velocity, departure side, and lane line 

type combinations tested. This result 

demonstrates that adequate LKA 

performance is achievable between the 

proposed lateral velocities of 0.2 m/s to 

0.6 m/s (0.7 ft./s to 2.0 ft./s). 

7. Inboard Lane Line Tolerances and 

Maximum Excursion Limit 

The Agency sought comment on what 

lane line tolerances and/or alert or 

intervention timing would be 

appropriate for LDW and LKA, 

respectively. As mentioned, NHTSA 

held concerns that the safety benefits 

afforded by LDW technology were 

diminished because consumers were 

disabling LDW systems to address 

nuisance alerts stemming from 

excessive activations. To improve 

consumer acceptance and increase 

safety benefits, NHTSA requested 

comment in its 2015 RFC notice on 

whether to revise certain aspects of 

NCAP’s LDW test procedure. In 

particular, the Agency proposed to 

tighten the inboard lane line tolerance 

for its LDW test procedure from 0.75 to 

0.3 m (2.5 to 1.0 ft.). The outboard lane 

line tolerance would remain ¥0.3 m 

(¥1.0 ft.) from the inside edge of the 

lane line. Through this, an LDW alert 

could only be issued within a window 

of +0.3 to ¥0.3 m (+1.0 to ¥1.0 ft.) with 

respect to the inside edge of the lane 

line to pass an NCAP LDW trial. This 

proposal effectively increased the space 

in which a vehicle could operate within 

a lane before the triggering of an LDW 

alert. 

The Agency’s proposal to revise the 

lane line tolerances received mixed 

support in 2015. One commenter stated 

the proposed change was ‘‘unduly 

prescriptive,’’ and given the typical 

driver reaction time (i.e., 1.2 s) 402 and 

target lateral velocity of 0.5 to 0.6 m/s 

(1.6 to 2.0 ft./s) prescribed in NCAP’s 

LDW test procedure, an LDW alert 

would have to be issued at a distance of 

0.6 to 0.72 m (1.9 to 2.4 ft.) to ensure 

that the majority of drivers could react 

in time to prevent a lane departure. 

Other commenters stated that some of 

the more robust systems available at the 

time could comply with the narrower 

specification and that the tolerance 

reduction should increase the required 

accuracy and quality of lane keeping 

systems, thus producing higher driver 

satisfaction, and, in turn, system use, 

compared to those systems that meet the 

current LDW requirements. Another 

commenter agreed that the narrowed 

lateral tolerance should reduce the 

issuance of false alerts on main 

roadways but cautioned the Agency that 

this change may not effectively address 

false alerts on secondary or curved 

roads. On these roads, the commenter 

stated vehicles not only tend to 

approach within one foot of lane lines, 

but also may cross them. 

Given NHTSA’s goal of reducing 

nuisance notifications to increase 

consumer acceptance of LDW systems, 

combined with several commenters’ 

statements that current LDW systems 

can meet the reduced test specification 

previously proposed, the Agency 

believed it reasonable to propose the 

reduced inboard lane tolerance of 0.3 m 

(1.0 ft.). 

Additionally, the Agency also 

contemplated reduced maximum 

excursion limits of the vehicle beyond 

the lane line. As previously noted, 

during the Agency’s study of LKA 

system behavior for increasing lateral 

velocity 403 for a small sample of model 

year 2017 vehicles, LKA performance 

was considered acceptable for instances 

where the SV did not cross the inboard 

leading edge of the lane line by more 

than 0.4 m (1.3 ft.).404 405 However, the 

maximum excursions over the lane 

marking recorded during the tests were 

also compared to the measured shoulder 

width of roads where fatal road 

departure crashes occurred. While the 

Agency found that most of the roadway 

departure crashes were on roads where 

the shoulder width exceeded 0.4 m (1.3 

ft.), such that a lane departure could 

have been prevented if a robust LKA 

system was engaged and functioned 

properly, the analysis also identified 

roadways where the shoulder width of 

the roadway was less than the 0.4 m (1.3 

ft.) maximum excursion limit (e.g., 

certain rural roadways) used in the 

Agency’s testing. The Agency concluded 

that only vehicles displaying robust 

LKA performance, including at higher 

lateral velocities, would likely prevent 

the vehicle from departing the travel 

lane on these roadways. Yet, as 

mentioned previously, NHTSA found 

that many of the assessed LKA systems 

exhibited inconsistent performance, 

particularly as the lateral velocity was 

increased. Several vehicles exhibited no 

system intervention, and others 

exceeded the maximum excursion limit 

as the lateral velocity was increased. 

Subsequent testing for six model year 

2019 vehicles revealed similar findings, 

with half of the vehicle models tested 

showing instances of no LKA response 

even at 0.2 m/s (0.7 ft./s). 

Since the Agency’s analysis showed 

that most fatal crashes identified in its 

study were on roadways having 

shoulder widths that exceeded the 

current Euro NCAP test excursion limit 

of 0.3 m (1.0 ft.), NHTSA expressed in 

its March 2022 RFC notice that adopting 

the Euro NCAP criterion may provide 

sufficient safety benefits. However, the 

Agency also requested comment on 

whether an even smaller excursion limit 

may be more appropriate to account for 

crashes occurring on roads with limited 

shoulder width. 

Summary of Comments 

Inboard Lane Line Tolerance 

Many commenters were in favor of 

harmonizing with Euro NCAP’s current 

LSS test protocol but did not specify 


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406Euro NCAP specifies that vehicles must issue 

an LDW alert prior to ¥0.2 m (0.7 ft.) from the 

inner lane edge for all lateral velocities up to at least 

1.0 m/s (3.3 ft./s) to receive credit for an LDW 

system under the Human Machine Interface (HMI) 

category. It does not dictate an inboard lane line 

tolerance prior to which an LDW system may not 

issue an alert. Similarly, Euro NCAP does not 

prohibit LKA interventions from occurring too 

early. 

whether they also found the lack of 

inboard lane line tolerances specified in 

these procedures for both passive and 

active safety technologies to be 

appropriate.406

When comparing inboard lane line 

tolerances for LDW and LKA system 

activation, Advocates suggested the 

tolerance for LKA should be tighter than 

that for LDW, since LKA involves 

automatic intervention whereas LDW 

relies on human reaction, which 

inherently introduces delays. In 

contrast, FCA suggested that the 

activation tolerance prior to lane 

markings for LKA should be wider than 

for LDW, since LKA ‘‘is more accepted 

by drivers due to fewer activations’’ and 

‘‘LKS systems need to deal with 

actuation latencies of steering and/or 

braking systems.’’ Rivian agreed with 

FCA that the LKA tolerance should be 

slightly higher for LKA than for LDW, 

since LKA systems can have a ‘‘dynamic 

activation range based on lateral 

velocity toward the line and may 

activate later than this range depending 

on the speed of the vehicle.’’ 

Auto Innovators suggested a defined 

inboard lane line tolerance, requesting 

that the current protocol value, 0.75 m 

(2.5 ft.), be used. The group explained 

that this will allow the driver ample 

time to intervene prior to the LKA 

intervention. They also noted that if the 

warning was forced to be issued closer 

to the lane line, it would become 

redundant with the active safety 

technology and would no longer 

provide the driver time to respond. 

Maximum Excursion Limits 

The Agency also received comments 

addressing the maximum excursion 

limits permissible for LKA interventions 

and/or LDW alerts. ASC, Aptiv, Auto 

Innovators, BMW, Intel, Tesla, and 

Toyota supported an excursion limit of 

0.3 m (1.0 ft.) over the inboard lane line 

for both LDW and LKA assessments 

instead of the 0.4 m (1.3 ft.) limit 

initially proposed by NHTSA for LKA. 

Auto Innovators and Toyota added that 

this limit was justified based on 

NHTSA’s 2018–2019 CISS data, which 

showed that most road departure 

crashes occurred when the departure 

distance from the lane marking was 

more than 0.3 m (1.0 ft.), providing 

reason not to reduce the excursion limit. 

Auto Innovators added that this 

excursion tolerance should be adequate 

to avoid crashes on road shoulders and 

limit interventions. Tesla stated that 

adopting a 0.3 m (1.0 ft.) excursion limit 

was sufficient to ensure that LKA 

systems would ‘‘maintain tight control 

over vehicle lateral motion in lane,’’ and 

suggested that the Agency maintain this 

limit for LDW as well. 

IDIADA stated that the Euro NCAP 

test protocol stipulates that the 

excursion limit (i.e., 0.3 m (1.0 ft.)) is 

referenced from the outer face of the tire 

to the inner edge of the lane marking. 

Since the lane markings are typically 0.2 

m (0.7 ft.) wide, this allows a vehicle to 

have 0.1 m (0.3 ft.) of actual excursion 

after the lane marking. The laboratory 

stated that the tolerance is provided to 

improve consumer acceptance, 

essentially preventing system designs 

that are overly intrusive such that they 

constantly correct vehicle trajectory, but 

is also limited enough to not cause 

safety concerns. BMW’s comments 

closely aligned with those of IDIADA. 

The automaker explained that, with a 

0.3 m (1.0 ft.) excursion limit, intrusion 

onto the shoulder (or into another lane) 

would be 0.15 to 0.2 m (0.49 to 0.66 ft.) 

given lane markings are typically 0.1 to 

0.15 m (0.33 to 0.49 ft.) wide, which 

should be adequate to avoid collisions 

with other obstacles. Furthermore, 

BMW asserted that reducing the 

excursion limit would require earlier 

system interventions at higher lateral 

speeds, which could increase the 

number of interventions overall and 

lead to reduced acceptance. 

Intel specifically remarked that the 

0.3 m limit was appropriate for LDW (in 

addition to LKA) ‘‘since it covers the flat 

and elevated road edges as a lane 

border.’’ Other commenters supported a 

0.3 m (1.0 ft.) excursion limit 

specifically for LKA testing. Honda 

commented that a 0.3 m (1.0 ft.) 

excursion limit was appropriate for 

LKA, acknowledging that the ability of 

a system to mitigate lane departures in 

the real world is associated with the 

amount of allowable excursion. HATCI 

and DENSO also recommended a 0.3 m 

(1.0 ft.) excursion limit for LKA, with 

DENSO remarking that LKA may 

become ‘‘cumbersome’’ when a driver 

must intentionally move into another 

lane to avoid an obstacle because of lane 

and tire widths if a lower limit is 

allowed. GM expressed support for the 

0.3 m (1.0 ft.) limit for LKA, stating that 

such a tolerance was sufficient to 

prevent roadway departures even when 

shoulder width is limited. However, for 

LDW, the automaker commented that 

such alerts should not be required until 

after the referenced excursion limit is 

reached to minimize nuisance alerts and 

subsequent system deactivation. 

Bosch supported an outboard 

excursion limit of 0.3 m (1.0 ft.) for 

LDW alert issuance and 0.4 m (1.3 ft.) 

for maximum vehicle excursion during 

LKA intervention but also supported 

aligning with Euro NCAP’s tolerances. 

ZF Group commented that the proposed 

0.4 m (1.3 ft.) excursion limit for LKA 

should be sufficient in most situations, 

but for construction areas or those with 

limited shoulder width, the company 

proposed that LKA should be disabled, 

and the driver should subsequently be 

notified. 

For LDW, Rivian suggested a 

maximum range of 0.3 m (1.0 ft.) over 

the lane line and 0.15 m after crossing 

the outer edge of the lane line as an 

‘‘acceptable activation range,’’ as this 

would allow for different LDW warning 

settings (e.g., early, normal, late). The 

automaker further commented that 0.3 

m (1.0 ft.) is an appropriate excursion 

tolerance for LKA and LDW testing 

involving lane markings, but not a road 

edge. Also specific to road edge testing, 

Rivian suggested a reduced excursion 

limit of 0.1 m (0.33 ft.) for systems 

offering road edge detection. For 

systems not designed for road edge 

detection, the company suggested that if 

such systems are able to meet the 0.1 m 

(0.33 ft.) excursion limit, they should 

score higher than those that can only 

meet the 0.3 m (1.0 ft.) limit. Similarly, 

Advocates suggested that different 

excursion limits are warranted for 

different conditions, stating that Euro 

NCAP proposes a tighter limit for their 

road edge detection test compared to 

their single line lane tests. Advocates 

also noted that the maximum excursion 

limit should be based on analysis of 

real-world data, including crashes and 

road dimensions, in the U.S. Like other 

commenters, MEMA suggested that the 

Agency should focus on road edge 

detection if it desires a ‘‘more targeted 

approach’’ for the excursion limit. 

CAS stated that a 0.3 m (1.0 ft.) 

excursion limit over the lane marking, 

as specified by Euro NCAP, was 

‘‘unacceptable,’’ and recommended that 

the limit ‘‘be reduced to zero to account 

for roads with limited or no shoulder 

width.’’ The group noted that lane 

markings serve to promote safety and 

often denote the edge of the road, such 

that an excursion of any extent over a 

lane line may induce a crash with other 

vehicles, pedestrians, or cyclists, or 

cause the vehicle to exit the roadway. 

In response to NHTSA’s notation that 

the 0.3 m (1.0 ft.) excursion limit is a 

Euro NCAP requirement, FCA stated 

that it supported harmonization efforts 

with other rating programs in general 


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96056 Federal Register / Vol. 89, No. 232 / Tuesday, December 3, 2024 / Notices 

407 It should be noted that the LDW excursion 

limit in Euro NCAP is¥0.2 m (¥0.7 ft.). 

408Lerner, N., Robinson, E., Singer, J., Jenness, J., 

Huey, R., Baldwin, C., & Fitch, G. (2014, 

September), Human factors for connected vehicles: 

Effective warning interface research findings 

(Report No. DOT HS 812 068), Washington, DC: 

National Highway Traffic Safety Administration. 

409Flannagan, C., LeBlanc, D., Bogard, S., 

Nobukawa, K., Narayanaswamy, P., Leslie, A., 

Kiefer, R., Marchione, M., Beck, C., and Lobes, K. 

(2016, February), Large-scale field test of forward 

collision alert and lane departure warning systems 

but cautioned NHTSA to consider the 

effect on U.S. driver acceptance when 

considering a reduced excursion limit. 

The manufacturer suggested that any 

further reduced excursion limit may 

translate to a more intrusive system, 

resulting in a reduction in acceptance. 

Finally, TRC did not recommend a 

specific tolerance, but suggested that the 

tolerance adopted for LKA should also 

be adopted for LDW. 

Response to Comments and Agency 

Decisions 

Inboard Lane Line Tolerance 

Based on the lack of definitive data 

regarding the most appropriate LDW 

alert warning time, and no clear 

consensus among commenters, the 

Agency has decided to retain its current 

0.75 m (2.5 ft.) inboard lane line 

tolerance for LDW activation during 

LKA testing at this time. This tolerance 

will also apply to LKA engagement. 

Neither an LDW nor LKA intervention 

shall occur when a vehicle is farther 

than 0.75 m (2.5 ft.) from the inboard 

edge of the lane line. NHTSA reasons 

this approach will allow manufacturers 

the flexibility to design LDW and LKA 

systems to better identify when a driver 

is actively steering and engaged in the 

driving task to suppress the alert and 

intervene when the turn signal is not in 

use. 

NHTSA acknowledges that many 

commenters responding to the March 

2022 RFC supported the whole or 

partial adoption of Euro NCAP’s LSS 

test protocol. In accordance with the BIL 

mandate, NHTSA seeks to align with 

other global rating programs whenever it 

is appropriate to do so. However, as 

previously noted, there is no inboard 

lane line tolerance provided for either 

Euro NCAP testing or for EU regulations 

regarding lane keeping systems. 

Consequently, if enabled, these systems 

may activate at any time prior to an 

excursion limit beyond the lane line. 

There is a need to better define when 

LDW or LKA should be suppressed, and 

an open-ended tolerance will not solve 

the issue of nuisance alerts or 

inappropriate intervention. 

NHTSA also has concerns with the 

initially proposed inboard tolerance of 

0.3 m (1.0 ft.). The Agency is still of the 

opinion that a tightened inboard lane 

line tolerance would likely deter the 

excessive alerting currently driving 

consumer dissatisfaction. However, 

based on the comments received, the 

Agency could also limit a manufacturer 

from issuing a legitimate alert regarding 

an impending/ongoing lane departure, 

or initiating an intervention, at an 

appropriate time. Based on these 

concerns, the Agency has decided to 

retain its current 0.75 m (2.5 ft.) inboard 

lane line tolerance for LDW activation 

during LKA testing at this time. NHTSA 

may again consider tightening this 

tolerance in the future once system 

confidence and accuracy improves or as 

additional lane keeping systems (i.e., 

LCA) are introduced. 

Maximum Excursion Limit for Vehicles 

During LKA Intervention 

The Agency received many comments 

in support of a¥0.3 m (¥1.0 ft.) 

excursion limit from the inboard lane 

line edge for both LDW issuance and 

LKA intervention. In addition to 

commenter support, the Agency notes 

that adoption of this maximum LKA 

excursion limit will harmonize 

NHTSA’s NCAP test requirement with 

Euro NCAP’s, meeting one of the 

Agency’s primary objectives.407 As 

such, NHTSA will move forward with 

the adoption of a maximum vehicle 

excursion of¥0.3 m (¥1.0 ft.) for its 

LKA test in NCAP. 

The Agency agrees that the ideal 

amount of allowed vehicle excursion 

beyond a lane marking would be zero, 

as CAS suggested. However, NHTSA is 

concerned that requiring the vehicle to 

remain solely between the lane lines, 

particularly at higher lateral velocities, 

may result in a potential increase in 

nuisance alerts and/or excessive 

activations, which could result in 

greater system deactivation. IDIADA 

and BMW noted that an excursion limit 

of¥0.3 m (1.0 ft.) from the inboard lane 

line edge translates to anywhere from 

0.1 m (0.3 ft.) to 0.2 m (0.6 ft.) of vehicle 

encroachment into the adjacent lane or 

shoulder. Given this, combined with the 

data supplied by Auto Innovators and 

Toyota showing that the departure 

distance from the lane marking for most 

road departure crashes was greater than 

0.3 m (1.0 ft.), NHTSA agrees with GM 

that this excursion allowance should be 

sufficient to prevent roadway 

departures, even on roads where 

shoulder width is limited. NHTSA also 

reasons that the adopted approach 

should balance consumer acceptance 

difficulties with real-world benefit. 

Further, NHTSA’s model year 2017 

and 2019 LKA testing demonstrated that 

compliance with this excursion limit is 

achievable, even up to lateral speeds of 

0.6 m/s (2.0 ft./s). Specifically, two of 

the total 11 vehicles tested were able to 

comply with an LKA excursion limit 

of¥0.3 m (¥1.0 ft.) at least once in a 0.6 

m/s (2.0 ft./s) test. Three additional 

vehicles fell between the¥0.3 m (¥1.0 

ft.) and¥0.4 m (¥1.3 ft.) limit at least 

once at this upper lateral velocity, 

demonstrating that some vehicles came 

within inches of achieving satisfactory 

performance during a trial. 

Finally, NHTSA will adopt the same 

maximum excursion limit of¥0.3 m 

(¥1.0 ft.) over the inboard lane line for 

LDW alert issuance. As previously 

discussed, for vehicles with LKA, LDW 

will become part of an expected LKA 

activation. Thus, maximum excursion 

tolerance of these lane keeping 

technologies will match, as TRC 

requested. NHTSA notes that the 

current LDW test procedure allows 

activation of LDW within the same 

tolerance range adopted (0.75 m to¥0.3 

m, or 2.5 ft. to¥1.0 ft.). 

8. LDW Alert Modalities and Requiring 

an LDW Alert During LKA Intervention 

As part of NHTSA’s March 2022 RFC 

notice, the Agency sought comment on 

whether it should award LDW credit to 

vehicles equipped with LDW systems 

that provide a passing alert, regardless 

of the alert type issued, or whether there 

are certain LDW alert modalities (such 

as visual-only warnings) that it should 

consider unacceptable when 

determining whether a vehicle meets 

NCAP’s performance test criteria. 

NHTSA also asked whether it should 

consider only certain alert modalities 

(such as haptic warnings) acceptable 

because they may be more effective at 

re-engaging the driver and/or have 

higher consumer acceptance. Finally, 

NHTSA questioned whether it was 

necessary to require that an LDW alert, 

designed to re-engage the driver, be 

issued when an LKA system is 

activated, since these systems are 

designed to intervene and provide 

steering and/or braking to prevent 

unintentional lane departures (e.g., 

when a driver is distracted). 

The Agency’s questions stemmed in 

part from concerns (similar to those 

raised for FCW) that LDW systems 

providing only a visual alert may be less 

effective than systems utilizing other 

alert modalities (i.e., auditory or haptic) 

in medium or high urgency 

situations.408 NHTSA notes that results 

from a large-scale telematics-based 

study conducted by UMTRI on LDW 

usage 409 raised questions as well. As 


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Federal Register / Vol. 89, No. 232 / Tuesday, December 3, 2024 / Notices 96057 

(Report No. DOT HS 812 247), Washington, DC: 

National Highway Traffic Safety Administration. 

410 80 FR 78522 (Dec. 16, 2015). 

411https://www.regulations.gov/comment/ 

NHTSA-2021-0002-4050. See citation 4. 

part of this effort, researchers 

investigated driver acceptance of LDW 

alerts in vehicles providing auditoryonly alerts and in vehicles where the 

driver had the option to select between 

either an auditory or haptic alert. When 

the latter was available, the study found 

the driver selected the haptic warning 

90 percent of the time; when this setting 

was chosen as the preferred alert setting, 

the driver turned the LDW system ‘off’ 

38 percent of the time. Thus, the LDW 

system was not providing alerts. For the 

system that only issued an auditory 

warning with no option for haptic alerts, 

LDW functionality was turned ‘off’ 71 

percent of the time. Based on the 

findings from UMTRI’s research, 

NHTSA tentatively concluded that 

haptic alerts improve driver acceptance 

of LDW systems. 

The Agency’s December 2015 notice 

also addressed the issue of drivers 

choosing to disable their vehicle’s LDW 

system.410 In that notice, the Agency 

referenced several studies finding that 

LDW system disablement arose from 

frequent false activations. In response to 

these findings and concern over 

diminished safety benefits due to 

consumer dissatisfaction with LDW 

systems, the Agency solicited comment 

at that time as well on whether it should 

award NCAP credit only to LDW 

systems that issue haptic alerts. NHTSA 

opined that haptic alerts may be viewed 

as less of a nuisance by consumers, 

offering greater consumer acceptance 

compared to auditory alerts and 

potentially improving the effectiveness 

of LDW alerts because of less frequent 

system disengagement. However, 

commenters responding to the 

December 2015 notice generally did not 

support a requirement for a specific 

warning type, with most suggesting the 

Agency should not require a specific 

LDW alert modality to promote system 

availability across a larger number of 

vehicles and afford flexibility to 

manufacturers so they may optimize 

human-machine interface (HMI) designs 

for a growing suite of ADAS. 

Summary of Comments 

Similar to FCW and BSW, comments 

received on the allowable alert types for 

LDW systems were varied. Some 

respondents recommended the Agency 

impose no restrictions on alert types, a 

few recommended certain alerts should 

be unacceptable, several requested 

additional requirements for certain alert 

modalities or multi-modal modalities, 

and others promoted a specific alert 

type. Commenters also provided mixed 

recommendations on which type of 

alert, if any, should be issued in the 

event a vehicle’s LKA system intervenes 

to prevent a lane departure. 

Allow All Alert Types 

Those in favor of allowing any type of 

LDW alert during Agency testing 

included Auto Innovators, Honda, 

IDIADA, HATCI, Intel, Rivian, Bosch, 

and an anonymous public commenter. 

Auto Innovators, citing a lack of 

evidence that one alert type is more 

effective than another, stated that 

NHTSA should pursue a technologyagnostic approach to allow 

manufacturers to pursue designs 

preferred by their customers. A public 

commenter agreed. Rivian stressed that 

the alert type is often a subjective 

preference and although many drivers 

prefer haptic warnings, not all do, and 

those that don’t should be able to 

purchase vehicles that have alerts 

suiting their preference.411 Further, the 

automaker opined that NHTSA should 

award credit for any form of alert since 

all modalities should increase the 

possibility that the driver will become 

reengaged. 

Like Auto Innovators, IDIADA 

stressed the importance that NHTSA be 

flexible with respect to alert type(s) so 

that manufacturers have greater 

opportunity to provide real-world 

benefits, particularly for a technology 

like LDW, which generally has lower 

consumer acceptance. HATCI expressed 

similar sentiments, stating that 

‘‘[current] flexibilities allow industry to 

optimize and adjust the alerts based on 

the multitude of ADAS technology 

installed, the interaction between the 

technologies, and research and 

development findings.’’ The 

manufacturer warned that restricting 

system alerts to specific modalities may 

limit future alert strategies and have 

unintended consequences as ADAS 

technology evolves and other systems 

are introduced. Auto Innovators 

suggested that the Agency should 

encourage manufacturers to develop the 

most effective systems, which may 

involve a suite of multimodal alerts and 

not simply a single modality type. 

Similarly, Honda noted that differences 

in effectiveness and consumer 

acceptance stemming from the use of 

various alert approaches cannot be 

captured based solely on alert modality 

and therefore restricting the alert types 

would not be justifiable. Intel stated that 

modality should not be restricted 

because credit should be based on alert 

effectiveness (i.e., an alert resulting in 

passing performance is effective, 

regardless of the alert modality type). 

Finally, noting that system reliability is 

a factor in consumer acceptance of LDW 

systems, not just warning type, Bosch 

also remarked that any alert modality 

type should be accepted for credit. 

Restrict Alert Types 

A few commenters recommended that 

the Agency award credit to certain alert 

types and not others. Aptiv and ASC 

encouraged the Agency to restrict 

auditory alerts to improve consumer 

acceptance and usage. Both entities 

cited UMTRI’s findings (referenced in 

the March 2022 RFC notice and again 

above) that 90 percent of test 

participants opted for haptic alerts over 

auditory alerts, and when an auditory 

alert was the only option, the LDW 

system was turned off 71 percent of the 

time. 

Add Requirements to Visual Alerts or 

Require Multiple Modalities 

Other commenters suggested that 

certain alert types may be acceptable, 

but only if they meet certain 

requirements or are paired with a 

second alert modality. 

DRI suggested that the Agency 

discontinue the acceptance of visual 

alerts, or alternatively, prescribe 

minimum characteristics for such alerts 

(i.e., size, color, brightness, location) to 

help gain the driver’s attention. The test 

laboratory contended that in many LDW 

systems, the visual alert, which is 

typically a telltale in the instrument 

panel that changes color, is ‘‘too small,’’ 

appears in ‘‘non-attention-capturing 

colors (e.g., white)’’, or is otherwise 

inconspicuous. The company also stated 

that a distracted driver’s gaze would 

likely not be forward-looking, such that 

a visual alert located in the instrument 

panel would not be helpful like an 

auditory or haptic alert would be to 

capture the driver’s attention. DRI 

further stated that a visual LDW alert is 

often intended to be an indicator to a 

driver regarding the ‘‘real’’ alert, which 

may be auditory or haptic, such that it 

serves to convey visually to the driver 

why they are hearing or feeling, rather 

than the visual alert being a warning in 

and of itself. As such, the laboratory 

opined that visual LDW alerts are not 

effective at alerting the driver unless 

they are combined with an auditory or 

haptic alert. Toyota and AAA expressed 

similar comments. 

Toyota noted that a visual-only LDW 

alert may not be effective for a 

distracted or drowsy driver. 

Accordingly, the manufacturer 

recommended that an LDW system 


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412Okuma et al. ‘‘A Study of Tactile Driver 

Interface using Seat Vibrations.’’ Transactions of 

Society of Automotive Engineers of Japan. Vol. 39, 

No. 6, November 2008, p.59–54. 

413 87 FR 13460. 414 87 FR 13460. 415https://www.regulations.gov/comment/ 

NHTSA-2021-0002-3856. See Appendix 2 for 

rationale and supporting data. 416 DOT HS 812 247. 

should be required to have two different 

warning modalities—visual plus either 

haptic or auditory, as research has 

shown that these warning types elicit 

essentially equivalent drivers’ response 

times.412 AAA recommended that any 

visual alert also be accompanied by a 

haptic alert. GM contended that 

multimodal (e.g., visual plus directional 

auditory or directional haptic) alerts are 

necessary for ‘imminent crash alerts’, 

but visual-only alerts are acceptable for 

‘cautionary crash alerts’ to limit 

instances of drivers turning off LDW 

systems due to alert annoyance. That 

said, the manufacturer opined that 

credit for LDW alerts in NCAP testing 

should only be provided for multimodal 

alerts that include both a visual and 

haptic or auditory alert. Like DRI, GM 

also suggested that the Agency impose 

additional requirements for visual 

alerts, recommending that visual alerts 

should not only ‘‘help explain the alert 

to the driver (including alert criticality)’’ 

but should also ‘‘be positioned such that 

they draw the driver’s attention to the 

general direction of the crash threat.’’ 

This directional requirement, referenced 

previously, was also suggested for 

haptic and auditory components of 

multimodal alerts. 

Other commenters also favored 

additional requirements for visual 

alerts. One anonymous commenter 

recommended that such alerts be 

directly visible (in the driver’s line of 

sight) without requiring the driver to 

look down to notice the indicator (e.g., 

in a heads-up display, instrument 

cluster that is fairly high on the 

dashboard, etc.). Similar to Toyota and 

AAA, however, the commenter stated 

that visual alerts presented outside of 

drivers’ line of sight could receive credit 

if a separate warning type (e.g., auditory 

or haptic) is also provided. FCA held 

the same view. The manufacturer, 

which, like others, also mentioned 

higher effectiveness and improved 

customer satisfaction for audio-visual 

and haptic-visual alerts, suggested that 

the visual warning should appear in the 

driver’s direct line of sight for dualmodality alerts to receive credit. 

Haptic-Only Alerts 

With respect to haptic warnings 

specifically, FCA commented that the 

Agency should not limit credit solely to 

haptic warnings, as consumer 

acceptance of LDW systems in general 

has improved in recent years because of 

improved line detection capability and 

overall system performance. 

Tesla recommended that NHTSA 

award credit to systems that issue haptic 

alerts, regardless of whether other alert 

modalities are provided. The 

manufacturer referenced research from 

the University of Michigan 

Transportation Research Institute 

(UMTRI) that cited drivers’ preference 

for haptic alerts.413 Similarly, IDIADA 

suggested that since haptic warnings 

have higher consumer acceptance rates, 

they may also offer higher real-world 

benefits if such systems are less prone 

to deactivation. Advocates favored 

requiring haptic alerts (to promote their 

adoption) if they improve driver 

acceptance, as NHTSA stated in the RFC 

Notice.414 The group suggested that 

automakers would still be able to 

implement additional human-machine 

interface (HMI) designs if they chose to. 

ZF Group suggested that the Agency 

award credit to haptic seatbelt warnings, 

as their research has shown them to be 

more effective than other alternatives. 

GM stated that the Agency should 

award additional credit to their Safety 

Alert Seat (SAS) vibration alerts, and to 

other haptic alerts that can support 

equivalent rationale.415 While TRC 

noted testing concerns with haptic 

alerts, explaining that alert flags for 

haptic alerts are sometimes difficult to 

collect due to sensor noise, especially 

for alerts issued from the seat or steering 

wheel, GM stated that SAS vibration 

alerts are triggered simultaneously with 

an auditory alert by the same ADAS 

signal and can be detected by various 

means during testing (e.g., voltage 

readings, vibration sensors, auditory 

microphone, etc.). GM stated SAS alerts 

allow non-visual crash alerts to be 

detected by hearing-impaired drivers, 

thus improving accessibility. Further, 

the manufacturer noted that in a largescale telematics-based study funded by 

NHTSA, SAS alerts, relative to auditory 

alerts, were preferred by drivers and 

also increased usage of the LDW 

system.416 More specifically, for 

vehicles with SAS vibration alerts, 

drivers left LDW on 62 percent of the 

time, compared to 29 percent of the time 

for vehicles offering only auditory 

alerts. 

Weight Alert Credit Depending on Type 

A few commenters suggested that 

different scores or ratings should be 

assigned to the various alert modalities. 

Rivian suggested that higher scores be 

assigned to systems proven to be more 

effective. Specifically, it recommended 

that the Agency should increase ratings 

for vehicles having alerts comprised of 

additional modalities beyond a visual 

cue but stated that vehicles offering 

visual-only alerts should not be 

penalized with a test failure. Likewise, 

ZF Group also recommended that 

NHTSA provide higher scores for alert 

types that reduce driver reaction time 

compared to other types. Along similar 

lines, citing both increased effectiveness 

and consumer acceptance for haptic 

alerts, one public commenter suggested 

that NHTSA reserve full credit for 

systems that offer haptic alerts, or which 

combine haptic alerts with visual or 

auditory warnings, and award partial 

credit to those systems that issue only 

a visual or auditory alert. 

Other General Topics on LDW Alerts 

The Agency received a few other 

general comments surrounding LDW 

alerts. One public commenter suggested 

that an LDW alert issued simultaneously 

with an LKA intervention should also 

receive credit. GM stated that NHTSA 

should only assess LDW functionality in 

cases where LKA fails to keep the 

vehicle in the lane per the test 

procedure requirements (regardless of 

whether the Agency maintains LDW as 

a separate assessment or integrates LDW 

assessments into an LKA test 

procedure). In such cases, the 

automaker recommended requiring a 

visual and non-visual alert, as 

mentioned previously. 

Advocates recommended that the 

Agency expedite additional research on 

HMI to identify alert modalities and 

designs that are most effective at 

reengaging the driver and ‘‘eliciting a 

safe, timely, and accurate response.’’ 

The organization suggested there may be 

further benefit realized from 

standardizing alerts, especially for 

drivers that use multiple vehicles. 

Contrary to this, HATCI favored 

flexibility with respect to alert types. 

The automaker mentioned that it 

supports adopting processes and/or 

performance-based methods developed 

by organizations such as SAE’s Human 

Factors committee to evaluate alert 

effectiveness to not limit future alert 

strategies for new ADAS technologies. 

Requiring an LDW Alert During LKA 

Intervention 

Several commenters, including AAA, 

AASHTO, Advocates, CAS, GM, Honda, 

Intel, ZF Group, and a public 

commenter, agreed that the Agency 

should specify that an LDW alert must 

be issued even when LKA is activated, 


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417 IDIADA defined ‘‘safety critical scenarios’’ as 

lane departure scenarios with a risk of road 

departure or a collision with other vehicles. 

418Commission Implementing Regulation (EU) 

2021/646 of 19 April 2021 laying down rules for the 

application of Regulation (EU) 2019/2144 of the 

European Parliament and of the Council as regards 

uniform procedures and technical specifications for 

the type-approval of motor vehicles with regard to 

their emergency lane-keeping systems (ELKS) 

[2021] OJ L133/31, § 3.5.3.1.2. 

419The two-dimensional polygon is defined by 

the vehicle’s axles in the X-direction (fore-aft), the 

outer edge of the vehicle’s tire in the Y-direction 

(lateral), and the ground in the Z-direction 

(vertical). 

mainly because they reasoned that reengaging the driver was important. CAS 

suggested that an LDW alert could 

inform the driver that either the LKA 

system has failed to respond, or the 

intervention required exceeded the 

system’s capabilities such that the 

driver’s response is required. AASHTO 

commented that the alert would serve to 

let the driver know the LKA system was 

intervening and that the vehicle was not 

altering its trajectory due to weather or 

road conditions. Similarly, AAA opined 

that the alert could serve to ensure the 

system intervention was not 

misinterpreted as a system malfunction. 

Intel requested some type of warning, 

explaining that it is preferable for a 

driver to become aware and respond 

during a lane departure event. IDIADA 

expressed that it was appropriate to 

issue an LDW alert in ‘‘safety critical 

scenarios,’’ 417 but not for other LKA 

interventions. 

Honda specifically mentioned that the 

system should issue a visual alert to best 

balance consumer acceptance and 

system effectiveness (i.e., safety 

benefits). That said, the automaker, 

along with many others noted below, 

asserted that LKA systems inherently 

provide a haptic alert when they move 

the steering wheel to actively prevent 

lane departures. GM also recommended 

issuance of a visual alert to limit driver 

nuisance and subsequent system 

deactivation. The manufacturer, like 

others, asserted that it may be beneficial 

to let the driver know that the LKA 

system has been activated, but this 

should be communicated via a visual 

alert, and additional non-visual alerts 

should not be required unless the LKA 

intervention is insufficient to prevent 

the driver from crossing the lane line. In 

such instances, GM recommended that 

a flashing visual alert should be used, 

along with an auditory or haptic alert. 

ZF Group suggested that an alert should 

be issued to the driver when LKA is 

activated, but that this alert should be 

different than an LDW warning to limit 

driver confusion. 

Many other commenters, including 

Auto Innovators, BMW, Bosch, FCA, 

HATCI, Rivian, Subaru, Tesla, and 

Toyota, objected to NHTSA requiring an 

LDW alert in the event of LKA 

activation. Bosch asserted, similar to 

Honda, that an additional LDW alert 

would be redundant as a warning to the 

LKA intervention. Similarly, Rivian 

explained that the steering and/or 

braking from the LKA intervention 

effectively alerts the driver to the fact 

they are drifting from their lane. The 

company further stated, and Toyota 

agreed, that LDW alerts should only be 

issued to warn the driver if the LKA 

system fails to prevent the vehicle’s 

departure from the lane. Toyota, Tesla, 

and Auto Innovators maintained that 

frequent LDW alerts can be annoying to 

drivers, with Tesla adding this is 

especially true for those that may 

actually be alert and intentionally 

drifting to prevent a hazard or for an 

upcoming turn. As such, the three 

commenters asserted NHTSA must find 

the right balance between LDW and 

LKA to realize the highest benefits. 

Other commenters, including BMW, 

FCA, and Subaru, also stated that an 

LDW alert is not needed if LKA 

operates. Subaru and BMW, along with 

Auto Innovators, indicated, like Rivian, 

that steering assistance (Subaru) and/or 

braking (BMW) from an LKA system 

should serve as an effective alternative 

to a haptic LDW alert. Subaru pointed 

to Euro NCAP’s 2016–2018 LSS 

protocol, which recognized LKA 

steering as a replacement for an LDW 

haptic alert, and BMW directed the 

Agency to EU regulations, which also 

aligned.418

Response to Comments and Agency 

Decisions 

Many of the comments submitted to 

the Agency’s most recent RFC notice on 

acceptable LDW alert types echoed 

those received previously in response to 

the Agency’s 2015 RFC notice. Namely, 

most respondents were concerned about 

consumer dissatisfaction with LDW 

alerts. Thus, they favored an alert 

requirement that is not prescriptive with 

respect to the type of alert modality so 

that alerts may be optimized for 

consumer preferences. Many also 

cautioned the Agency that requiring an 

LDW alert during an LKA intervention 

may exacerbate existing consumer 

acceptance issues for LDW and LKA 

systems. 

Considering the comments received, 

the Agency has decided to require a 

visual LDW alert for the Agency’s LDW/ 

LKA tests; the LKA intervention itself 

will serve as a secondary haptic alert 

component. In addition, at the 

manufacturer’s option, other auditory or 

haptic alert signals may be provided to 

the driver to warn of an impending lane 

departure. To pass the LDW 

requirements for the LKA tests, no alert 

component may be issued before the 

lateral position of the vehicle, 

represented by a two-dimensional 

polygon,419 is within 0.75 m (2.5 ft.) of 

the inboard edge of the lane line (i.e., 

the line edge closest to the vehicle when 

the lane departure maneuver is 

initiated), and the visual LDW alert 

component and haptic LKA intervention 

must be issued before the lane departure 

exceeds 0.3 m (1 ft.). In addition, the 

visual alert must be issued prior to, or 

concurrent with, the start of the LKA 

intervention. 

NHTSA generally agrees with 

commenters who stated visual alerts, 

which tend to be more inconspicuous, 

may best balance consumer acceptance 

and, thus, system effectiveness (i.e., 

they limit driver annoyance and 

subsequent system deactivation) at low 

lateral velocities when the LKA system 

should be capable of providing the 

correcting action. In these situations, 

visual alerts are informational as they 

can convey to the driver that the LKA 

system is intervening. As some 

respondents stated, without this 

confirmation, the driver may not know 

whether the system is malfunctioning or 

whether some other condition, such as 

poor weather or road conditions, is 

altering the vehicle’s path. This 

rationale serves as the basis for a visual 

alert component requirement. However, 

the Agency also agrees NHTSA should 

not dictate additional specifications for 

the required visual alert beyond the 

timing requirements mentioned 

previously. The Agency does not find it 

necessary to impose additional visual 

alert requirements, such as those 

relating to color, brightness, or location 

as requested by DRI and GM, because it 

does not wish to limit design flexibility. 

Additionally, manufacturers may 

choose to issue a visual alert that 

becomes escalatory (e.g., flashing) in 

nature after some point, as GM 

suggested, but this is not required. 

Additionally, NHTSA will consider 

the LKA intervention itself to be a 

haptic alert, as several commenters 

requested. An LKA intervention that is 

clearly related to the lateral control of 

the vehicle and is noticeable by the 

driver (e.g., notable heading correction 

that prevents the vehicle from exceeding 

the allowable lateral deviation over the 

inboard edge of the lane line (i.e., 0.3 m 

(1 ft.)), such as that ensuing from 

steering and/or braking, sufficiently 

provides feedback to a driver such that 


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it meets the requirements for a haptic 

LDW alert. The decision to consider an 

LKA steering intervention to satisfy the 

requirements for an LDW haptic alert 

aligns with the LDW alert requirements 

outlined in Euro NCAP’s LSS test 

protocol for its LDW tests. This decision 

also reflects the Agency’s agreement 

with respondents who expressed that 

visual LDW alerts are not effective at 

eliciting a timely response from an 

inattentive driver, when necessary, 

unless they are combined with an 

auditory or haptic alert. The Agency 

maintains this position regardless of 

whether a visual alert is positioned in 

such a way that it is directly in the 

driver’s [typical] line of sight. 

While the Agency has prescribed a 

visual alert component to provide 

information to the driver and a haptic 

alert component in the form of a notable 

heading correction, it will not stipulate 

the modality (i.e., auditory versus 

haptic) for any additional LDW alert 

components the manufacturer may wish 

to include. A separate haptic or auditory 

LDW alert can serve to re-engage the 

driver in situations where either (1) the 

LKA system has failed to respond or (2) 

the system may be responding, but the 

intervention that is necessary may 

exceed the LKA system’s capabilities 

such that the driver’s response may also 

be required. Toyota’s research showed 

that both warning types elicit essentially 

equivalent response times from drivers, 

suggesting it is not necessary for 

NHTSA to be overly prescriptive at this 

time. NHTSA also agrees with Honda’s 

assertion that differences in 

effectiveness and consumer acceptance 

stemming from the use of various alert 

approaches cannot be captured solely 

based on alert modality and therefore 

restricting acceptable alert types would 

not be justifiable. The Agency also 

reasons there is merit to Bosch’s 

comment that system reliability also 

factors into consumer acceptance of 

LDW systems, not just warning type, 

and agrees with Toyota, Tesla, and Auto 

Innovators that it is necessary to find 

the right balance between LDW alerts 

and LKA interventions to realize the 

highest safety benefits. Thus, based on 

the lack of consensus on best practices 

that optimize consumer acceptance and 

system effectiveness, it is the Agency’s 

belief that vehicle manufacturers are 

best suited to optimize LDW alerts for 

this purpose. By allowing manufacturers 

to choose whether to issue a separate 

auditory or haptic LDW alert during an 

LKA intervention (instead of simply 

relying on the LKA intervention itself), 

it will help to abate current consumer 

acceptance issues for LDW and LKA 

systems, a concern cited by many 

commenters. 

NHTSA will also refrain from 

prescribing specifications (e.g., type, 

location, decibel level, etc.) for any 

additional LDW alert components at this 

time, as GM requested. Additional 

research is needed to gauge how certain 

haptic alert types/locations (e.g., seat 

belt tug, seat/steering wheel vibration) 

and auditory alert specifications (e.g., 

decibel level) alter system effectiveness 

before requiring further standardization. 

Should research data become available 

that better describes desirable (or, 

alternatively, undesirable) 

characteristics of auditory or haptic alert 

components, the Agency will consider 

adopting specifications for these 

additional modalities. Similar 

considerations will be made for the 

required visual alerts. NHTSA will 

consider being more prescriptive for 

visual alerts if new data suggests there 

is a safety need. 

For haptic alerts specifically 

(including the LKA intervention and 

any additional haptic alerts), NHTSA 

will require that manufacturers provide 

additional information to NCAP’s test 

laboratories to detail how to accurately 

record haptic signals without incurring 

damage to the test vehicle. 

Manufacturers who choose not to 

provide laboratories with such 

information or opt to provide 

information that is deemed insufficient 

for data collection, may risk not passing 

the LKA tests if the laboratories are 

unable to capture the alert flag for a 

haptic signal to ensure it meets the lane 

line requirements. This additional 

requirement is necessary because alert 

flags for haptic alerts may be difficult to 

collect due to sensor noise, particularly 

for alerts issued from the vehicle seat or 

steering wheel. Additionally, this 

additional requirement will not hinder 

a vehicle manufacturer’s ability to 

continue to optimize alerts for current 

and future technologies as they see fit. 

Finally, the Agency is concerned 

about the limited effectiveness and low 

consumer acceptance of LDW and its 

potential impact on the acceptance of 

LKA, which has demonstrated higher 

system effectiveness. However, LDW 

has merit and the updates the Agency is 

making for its lane keeping tests will 

provide sufficient restrictions to ensure 

nuisance LDW alerts are reduced during 

real-world driving. NHTSA’s strategy 

will ensure higher real-world benefits 

for lane keeping systems overall while 

also providing manufacturers with the 

flexibility to optimize alerts for 

consumer preferences and future alert 

strategies for new ADAS technologies, 

which many commenters requested. 

9. User-Configurable Settings for LDW 

and LKA Tests 

Currently, the Agency requires at least 

one warning time setting to meet the test 

procedure criteria for LDW testing. 

NHTSA did not specifically request 

comment on the appropriate settings to 

use for LDW and/or LKA during its 

NCAP testing, but the Agency received 

several comments on this topic. 

Summary of Comments 

For LKA systems with adjustable 

settings, Honda recommended that the 

Agency evaluate LKA using the middle 

setting, as it is ‘‘the best compromise’’ 

to properly assessing system 

capabilities. HATCI proposed that 

NHTSA utilize the default system 

settings during testing. The commenter 

explained that their research has shown 

that most Hyundai and Kia customers 

do not change ADAS settings after 

purchasing a new vehicle and that 

changing the settings for testing 

purposes would likely not be most 

representative of most real-world 

driving situations. The automaker 

recommended that the Agency conduct 

a similar, fleet-wide study, and use 

those findings for system settings to 

guide future test procedural changes. 

One public commenter suggested that 

LDW and LKA systems should be 

required to be default ‘ON’ at the start 

of every trip. However, Auto Innovators 

suggested that the ‘Default ON’ 

requirement should be changed to ‘Last 

saved setting’ because ‘Default ON’ has 

low customer acceptance in Europe. 

Response to Comments and Agency 

Decisions 

Aligning with its decisions for FCW 

and BSW, the Agency has decided to set 

the timing for the LDW alert and LKA 

intervention to the middle (or next 

latest) setting (if adjustable) during its 

LDW/LKA evaluations, as previously 

shown in Figure 2. The Agency will not 

adopt the default setting for the LDW 

alert or LKA intervention, as HATCI 

requested. NHTSA concludes, similar to 

its earlier decision for FCW, that it is 

reasonable to expect that the setting 

most preferred by drivers would (or 

rather, should) be the default setting, 

and this setting should generally fall in 

the middle of the range of driver setting 

preferences that span either earlier or 

later alert settings. Further, NHTSA 

notes that these system setting 

configurations align with Euro NCAP’s 

LSS test protocol. For LDW and LKA 

systems having only two settings, the 

Agency will select the later of the two 

settings to align with Euro NCAP’s 

requirements. This test setting will meet 


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420The initial lateral offset (based on the vehicle 

width and the desired lateral velocity) of the 

vehicle from the centerline is to ensure the SV is 

being operated at the desired steady state lateral 

velocity before LKA and LDW operate. 

421Commission Implementing Regulation (EU) 

2021/646 of 19 April 2021 laying down rules for the 

application of Regulation (EU) 2019/2144 of the 

European Parliament and of the Council as regards 

uniform procedures and technical specifications for 

the type-approval of motor vehicles with regard to 

their emergency lane-keeping systems (ELKS) 

[2021] OJ L133/31, § 2.2. 

422American Association of State Highway and 

Transportation Officials (AASHTO). (2018). Policy 

on Geometric Design of Highways and Streets (7th 

Edition), including 2019 Errata. American 

Association of State Highway and Transportation 

Officials (AASHTO). Table 3–7. Minimum Radius 

Using Limiting Values of e and f. 

NHTSA’s middle (or next latest) LDW/ 

LKA setting requirement. Lane centering 

functions will also be set to ‘Off’ for all 

LDW and LKA tests in alignment with 

Euro NCAP’s LSS test protocol. 

Tests will also be conducted without 

cruise control (i.e., conventional or 

adaptive cruise control) engaged. The 

longitudinal speed of the SV will be 

maintained through manual or robotic 

control. Since cruise control is designed 

to regulate a vehicle’s longitudinal 

movement and there is no vehicle 

present in the forward path of the SV 

during NCAP’s LDW/LKA tests, NHTSA 

does not expect the use of manual/ 

robotic control or cruise control to affect 

how the SV’s speed is maintained 

during a test trial. The Agency also does 

not expect that cruise control should 

impact the SV’s lateral movement. That 

being said, NHTSA will conduct testing 

utilizing only one method of speed 

control to ensure that the performance 

of one vehicle system (LKA) is not 

affected in any way by the performance 

of another system (cruise control). As 

mentioned in the BSI discussion, testing 

with manual or robotic control in lieu 

of cruise control is appropriate since 

consumers may sometimes opt not to 

use a cruise control feature, particularly 

on non-highway roads. 

Regarding the system settings upon 

‘‘key on,’’ NHTSA will require that the 

lane keeping technologies (i.e., LDW 

and LKA systems) appear ‘Default ON’ 

during each ignition/key cycle. While 

the Agency is not prohibiting a 

disabling function for lane keeping 

technologies in its NCAP evaluation, it 

is taking steps to reduce the false 

positive alerts and activations that 

prompt a driver to turn off the systems 

in the first place. Drivers should be able 

to adjust their system’s settings to meet 

their personal preference instead of 

needing to disengage the system 

altogether. 

10. Radius of Curvature 

In its LSS Protocol, Euro NCAP 

specifies use of a 1,200 m (3,937.0 ft.) 

curve and a series of increasing lateral 

offsets to establish the desired lateral 

velocity of the SV towards the lane line 

it must respond to. In the proposed LKA 

tests in the March 2022 RFC notice, the 

SV, laterally offset from the center of its 

travel lane,420 is driven at a steady 

velocity of 72 kph (44.7 mph). After a 

short period of steady-state driving, the 

SV driver (e.g., robot or human input) 

initiates steering to follow a 1,200 m 

(3,937 ft.) radius curved path until the 

desired lateral velocity towards the lane 

line is achieved. The SV driver then 

releases the steering wheel. Preliminary 

NHTSA tests have indicated that use of 

a 200 m (656.2 ft.) curve radius provides 

a clearer indication of when an LKA 

intervention occurs when compared to 

the baseline tests performed without 

LKA, a process specified by the Euro 

NCAP LSS protocol. This is because the 

small curve radius allows the SV to 

establish the desired lateral velocity 

more quickly, requires less initial lateral 

offset within the travel lane, and allows 

for a longer period of steady state lateral 

velocity to be realized before an LKA 

intervention occurs. Given the findings 

from the Agency’s testing, it sought 

comment on whether a 200 m (656.2 ft.) 

curve radius was more appropriate for 

inclusion in NHTSA’s LKA test 

procedure than the 1,200 m (3,937.0 ft.) 

radius currently specified in Euro 

NCAP’s protocol. 

Summary of Comments 

Agree With Adopting a 1,200 m (3,937.0 

ft.) Radius of Curvature 

Many commenters did not support a 

reduction in curve radius to 200 m 

(656.2 ft.) and preferred that the Agency 

adopt the 1,200 m (3,937.0 ft.) radius 

specified by Euro NCAP instead. 

Commenters voiced concerns over 

potential lack of system intervention, 

unwanted consequences (including a 

reduction in customer satisfaction and 

system acceptance), and real-world 

relevance. 

Several commenters, including GM, 

Toyota, Honda, and Auto Innovators, 

stated that the steering input (e.g., 

constant larger steering angle/torque, 

higher steering velocities/speeds) and 

lack of steady state lateral velocity (Auto 

Innovators) required to navigate a tight, 

200 m (656.2 ft.) curve would appear as 

an intentional steering input, akin to a 

deliberate lane change or maneuver to 

avoid roadway hazards, not an 

unintentional drift from the lane, like 

LKA is designed to prevent. In such 

instances, GM and Auto Innovators 

asserted that LKA systems may not 

intervene if a small radius of curvature 

is used during NCAP testing. Likewise, 

Rivian mentioned that although a 

smaller curve radius may make it easier 

during testing to determine when LKA 

activates, ‘‘a sharper attack angle’’ 

toward the lane line may override the 

LKA system in some vehicles such that 

the Agency would not observe the LKA 

systems’ true capabilities at higher 

lateral velocities. Conversely, Honda 

stated that adopting a small curve radius 

for NCAP assessments may encourage 

future LKA system designs to provide 

undesired steering intervention even in 

situations where drivers intentionally 

input higher steering velocities, such as 

when the driver is intentionally 

changing lanes without using the turn 

signal or during emergency avoidance 

maneuvers. The automaker further 

stated that adopting a smaller curve 

radius for testing purposes may have a 

negative effect on an LKA system’s 

ability to perform its intended design 

function and on consumer acceptance, 

and in turn, safety benefits. Bosch and 

Subaru asserted that evaluating LKA 

operation in a smaller, 200 m (656.2 ft.) 

radius curve may prompt a more 

aggressive system intervention if the 

vehicle deviates from the lane than 

would typically be expected for normal 

LKA operation, resulting in reduced 

driver comfort, satisfaction, and overall 

acceptance of LKA. Further, Auto 

Innovators stated that a 200 m (656.2 ft.) 

curve radius may encourage system 

designs that issue an excessive number 

of alerts, particularly for intentional 

maneuvers. Auto Innovators indicated 

this would be in conflict with EU 

regulation 2021/646 on ELKS, which 

‘‘includes a requirement to ‘minimize 

warnings and interventions for driver 

intended maneuvers.’’ 421

Several commenters, including FCA, 

suggested that the Agency align with 

Euro NCAP’s radius of curvature 

because it better represents real-world 

situations. Specifically, Toyota 

referenced AASHTO’s ‘‘A Policy on 

Geometric Design of Highways and 

Streets’’ manual and stated that the 

potential test condition (i.e., navigating 

a 200 m curve at 72 kph) is at the limit 

of road design and therefore not 

appropriate.422 Toyota provided a table 

showing that a design speed of 70 kph 

(45 mph) corresponds to a minimum 

radius of 203 m (666.0 ft.). HATCI stated 

that a 200 m (656.2 ft.) radius may be 

‘‘a startling input for a vehicle driving 

in a straight lane’’ and seemed 

unrepresentative of a real-world 

situation. The group further asserted, 

like Honda, that such a change made to 

improve testing may have unintended 


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423Wiacek, C., Forkenbrock, G., Mynatt, M., & 

Shain, K. (2019), Applying lane keeping support 

test track performance to real-world crash data. 26th 

International Technical Conference for the 

Enhanced Safety of Vehicles, Eindhoven, 

Netherlands. Paper Number 19–0208. 

consequences in how future derivations 

of the technology operate. Finally, GM 

pointed to NHTSA’s proposed BSI test 

procedure, which uses an 800 m (2,625 

ft.) curve for an intentional lane change, 

in support of its opinion that a 1,200 m 

(3,937.0 ft.) curve more accurately 

represents an unintentional drift out of 

the lane. 

Several commenters remarked on a 

variety of other potential consequences 

of adopting a reduced curve radius. For 

example, Bosch remarked that a 

reduction in radius to 200 m (656.2 ft.) 

could create challenges for test 

execution. ZF Group cautioned that 

NHTSA should not change the curve 

radius too drastically, especially 

without further research and 

consideration for the consequences of 

doing so, since Euro NCAP’s LSS 

protocol resulted from coordinated 

efforts of both vehicle manufacturers 

and suppliers. 

Agree to a Radius of Curvature Between 

200 m and 1,200 m (656.2 ft. and 

3,937.0 ft.) 

If a smaller curve radius is preferred, 

Subaru suggested that the Agency adopt 

an 800 m (2,624.7 ft.) curve radius. Intel 

commented that it would support a 

reduced curve radius up to 700 m 

(2,296.6 ft.). However, the company 

cautioned that even this radius may be 

unacceptable since drivers tend to cross 

lane markings while in a turn, which 

may elicit false positive warnings. 

IDIADA recommended that the 

Agency use variable radii (between 200 

m and 1,200 m, or 656.2 ft. and 3,937.0 

ft.) and the same arc length to generate 

multiple lateral speeds towards the lane 

line instead of one fixed radius and 

variable arc lengths to generate the 

lateral speeds, as used by Euro NCAP. 

The laboratory stated that the 

appropriate lateral speed range of 0.1 m/ 

s to 0.6 m/s could likely be generated 

within radii ranging between 200 m 

(656.2 ft.) and 1,200 m (3,937.0 ft.). 

Agree With Adopting a 200 m (656.2 ft.) 

Radius of Curvature 

Other commenters, like the ASC, 

BMW, and CAS, remarked that they 

would support reducing the curve 

radius to 200 m (656.2 ft.). However, 

BMW stated that the company’s support 

was contingent on there being a long 

period of steady state lateral velocity 

(also referenced by Auto Innovators) to 

be classified as an unintended lane 

departure. CAS commented that it was 

‘‘essential’’ to add both curve radii to 

the LKA test procedure to ensure that 

LKA systems are not designed to a test, 

but instead designed to perform well in 

multiple real-world conditions, 

especially since such additions would 

‘‘impose no additional cost on 

manufacturers.’’ 

General Comments 

Advocates recommended that NHTSA 

provide comparative performance data 

to show there are benefits of adopting a 

smaller curve radius rather than a 1,200 

m (3,937.0 ft.) curve. Advocates also 

stated that ‘‘convenience or expediency 

in testing should not be a substitute for 

robust and accurate protocols.’’ 

Response to Comments and Agency 

Decisions 

NHTSA is adopting a 1,200 m (3,937.0 

ft.) curve radius for SV travel paths in 

its LKA test procedure. 

Based on the comments received, 

NHTSA concludes a larger (i.e., 1,200 m 

(3,937.0 ft.)) curve radius rather than a 

smaller (i.e., 200 m (656.2 ft.)) radius is 

most appropriate for its LKA testing. In 

an unintentional lane departure, the 

vehicle would be expected to drift out 

of its lane rather than abruptly turn, as 

some commenters noted. As such, curve 

radii for unintentional lane departures 

would be expected to be larger than 

those of intentional lane changes. Along 

these lines, NHTSA finds merit in GM’s 

comment noting the Agency’s BSI test 

procedure for assessing intentional lane 

changes includes a (now-adopted) curve 

radius of 800 m (2,625 ft.), a radius 

significantly larger than the 200 m 

(656.2 ft.) curve radius considered for 

NHTSA’s LKA testing, which simulates 

unintentional lane departures. The 

Agency also sees validity in comments 

that a smaller curve radius may signal 

an intentional departure due to the 

necessary steering input, such that LKA 

system designs which take driver intent 

into account may not engage the LKA 

system as expected. NHTSA also 

acknowledges the opinion that 

evaluation of LKA capabilities at small 

curve radii may encourage intervention 

in cases where it is not desired. Besides 

being potentially hazardous, excessive 

warnings and false activations, in 

addition to aggressive interventions, 

may deter consumers from enabling lane 

keeping technologies, thus reducing 

potential benefits, as several 

respondents suggested. 

The Agency will not proceed as 

IDIADA requested and adopt variable 

(smaller) radii for LKA testing for this 

upgrade. Although the Agency 

recognizes CAS’s concern regarding the 

use of a single curve radius to evaluate 

LKA system performance, NHTSA also 

agrees with FCA, Toyota, and HATCI 

that the use of a curve radius of 200 m 

(656.2 ft.) would be aggressive and not 

necessarily representative when 

considering real-world events involving 

straight roads, even if considering 

intentional lane departures. Adopting 

smaller curve radii would also deviate 

from Euro NCAP’s LSS test protocol for 

the test conditions adopted by NHTSA. 

As NHTSA aims to harmonize its NCAP 

with other testing programs globally 

unless there are compelling reasons to 

do otherwise, it is best to mirror Euro 

NCAP and adopt a 1,200 m (3,937.0 ft.) 

curve radius for SV travel paths in its 

LKA test procedure at this time. 

Although NHTSA acknowledges the 

use of a smaller curve radius could 

produce a positive effect on test 

conduct, NHTSA agrees with 

Advocates’ comment that the Agency 

should first quantify any benefits of 

adopting any curve radius smaller than 

1,200 m (3,937.0 ft.). While the Agency 

does not currently have plans to 

conduct research to compare track tests 

of LDW and LKA to real-world data for 

different combinations of curve radius, 

vehicle speed, and departure timing, 

should it choose to pursue such testing 

in the future, NHTSA would consider 

the need to amend the prescribed curve 

radius or to add additional assessments 

at that time based on the data. 

11. Adding a Road Edge Detection Test 

In its March 2022 RFC notice, NHTSA 

recognized that Euro NCAP has adopted 

a road edge detection test that is 

conducted similarly to the group’s LKA 

tests, but which does not require the use 

of lane markings. The Agency also 

acknowledged that, while the number of 

vehicles equipped with an ability to 

recognize and respond to road edges not 

defined with a lane line may presently 

be low, there are U.S. roadways on 

which this capability could prevent 

crashes. In a study of fatal crashes using 

2005 to 2007 National Motor Vehicle 

Crash Causation Survey (NMVCCS) and 

2017 Crash Investigation Sampling 

System (CISS) lane/roadway departure 

cases that was undertaken (1) to classify 

the shoulder type present on the side of 

the roadway when a vehicle first 

departed its travel lane and (2) to 

estimate the shoulder width just after 

departure, NHTSA identified fatal 

crashes where lane markers were not 

present on the side of the roadway 

where a departure occurred.423 In these 

cases, LKA would not provide any 

benefit unless it had the capability to 

identify the edge of the roadway. 


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424The Agency believes FCA’s comment was 

referring to two-lane, two-direction roadways 

having only a centerline. 

425Reagan, I.J., Cicchino, J.B., Kerfoot, L.B., & 

Weast, R.A. (2018). Crash avoidance and driver 

assistance technologies—Are they used? 

Transportation Research Part F: Traffic Psychology 

and Behaviour, 52, 176–190. https://doi.org/ 

10.1016/j.trf.2017.11.015. 

426Reagan, I.J., Cicchino, J.B., & Montalbano, C.J. 

(2019). Exploring relationships between observed 

activation rates and functional attributes of lane 

departure prevention. Traffic Injury Prevention, 

20(4), 424–430. https://doi.org/10.1080/ 

15389588.2019.1569759. 

In its March 2022 RFC notice, the 

Agency also recognized that it had 

received public comments pertaining to 

the addition of a road edge detection 

test in response to its 2015 RFC notice. 

Specifically, Mobileye recommended 

that the Agency add not only road edge 

detection scenarios but also scenarios 

that include curbs and non-structural 

delimiters such as gravel or dirt to 

reflect real-world conditions and crash 

scenarios more accurately. Similarly, 

Bosch suggested that NHTSA consider 

introducing road edge detection 

requirements in addition to lane 

markings since not all roads have lane 

markings. 

Given the safety need and commenter 

suggestions, NHTSA sought comment in 

its March 2022 RFC notice on whether 

it should add Euro NCAP’s road edge 

detection test to NCAP for either its 

LDW and/or LKA assessments to 

address crashes that occur where lane 

markings may not be present. 

Summary of Comments 

In Favor of Adding a Road Edge 

Detection Test 

AASHTO, Aptiv, ASC, CAS, GM, 

Intel, Rivian, Bosch, ZF Group, and a 

public commenter recommended that a 

road edge detection test be added to 

address roads where lane markings are 

not present, or the markings have faded 

or are worn. AAA, Advocates, IDIADA, 

CAS, IIHS, and Toyota were also in 

favor, citing crash frequency and/or 

severity as a reason for inclusion. 

Advocates expressed support for the test 

scenario’s inclusion because the Agency 

identified road edge departures as the 

third most common lane keeping 

scenario. Likewise, Toyota pointed to 

NHTSA’s 2018 to 2019 CISS data which 

showed that there were no lane 

markings on the side of departure in 

approximately 30 percent of road 

departure cases. AAA commented that 

the possibility of injury and/or death 

increases for roadway departures. 

IDIADA similarly commented that 

rollovers may stem from roadway 

departures, therefore making road edge 

detection an important technology, and 

IIHS remarked that crashes with fixed 

objects are a common occurrence when 

vehicles leave the road, accounting for 

32 percent of passenger vehicle 

occupant fatalities (7,253 people) in 

2019. IIHS further asserted that ‘‘44 

percent of these deaths occurred on 

minor roads, which are more likely than 

other road types to have unmarked road 

edges.’’ The group also stated that 

systems capable of detecting unmarked 

road edges should also be better able to 

detect obstructed or worn lane lines. 

GM stated that it supported a road 

centerline plus road edge configuration 

if NHTSA elected to add a road edge 

detection test to its LKA protocol, since 

such an arrangement would accurately 

represent a common U.S. roadway 

condition. 

Vayyar did not comment specifically 

on including a road edge detection 

scenario in NCAP but did state that it is 

‘‘highly advisable to monitor unmarked 

road edges’’ and noted that this can 

often be achieved using radar. 

A Road Edge Detection Test Is 

Unnecessary 

Two commenters, FCA and Subaru, 

were not in favor of adding a road edge 

detection test to NCAP’s LDW and/or 

LKA test procedures. FCA cited low 

frequency of single lane lines 424 in the 

U.S. relative to other countries as a 

reason not to add a road edge detection 

scenario. Subaru opined that adding a 

road edge detection test to U.S. NCAP 

is unnecessary, but also stated that 

NHTSA should conduct further analysis 

of crash data to ascertain the relative 

frequency of road departures on roads 

with unmarked edges to better gauge 

representative conditions for road edge 

testing in the U.S. 

Include for LDW, LKA, or both systems? 

AAA, TRC, CAS, Rivian, and ZF 

Group suggested adding a road edge 

detection test to assess both LDW and 

LKA systems. Honda expressed support 

for adding a road edge detection test for 

both LDW and LKA if real-world data 

supports its inclusion, and Advocates 

indicated support for adding the 

assessment for both technologies if any 

LKA system capable of identifying a 

road edge also issues an LDW alert prior 

to automatic intervention. ASC 

suggested that adding a road edge 

detection test for both LDW and LKA 

would be appropriate, stating that 

inclusion of this test scenario would 

improve the safety benefits for both 

systems. GM additionally voiced 

support for adding the test scenario 

assessment for both systems, though 

they referenced only improved safety 

benefits for LKA. Both Intel and IIHS 

suggested that it would be reasonable to 

adopt the test for LDW, but stated 

priority should be given to LKA, with 

IIHS adding that their research has 

shown that drivers are more likely to 

use LKA compared to LDW,425 and LKA 

systems that provide earlier and more 

frequent steering input to avoid lane 

departures were used more by drivers 

than LKA systems with later and less 

frequent interventions.426 IDIADA 

stated that since a road edge detection 

test represented a ‘‘safety critical 

scenario,’’ it was most relevant for the 

active technology, LKA. 

Adopt Euro NCAP’s Test 

AAA, ASC, CAS, GM, HATCI, IIHS, 

MEMA, Bosch, and Tesla specifically 

mentioned adding Euro NCAP’s road 

edge detection test to the U.S. test 

protocol. IIHS stated that since this test 

has been part of Euro NCAP’s protocol 

since 2018, vehicle manufacturers 

should be ‘‘reasonably familiar’’ with it 

and should already be developing or 

even implementing systems having road 

edge detection capability. For those 

vehicles lacking this capability, 

however, Bosch asserted that adding 

this test would drive the availability of 

these more robust LKA systems through 

the fleet. GM and MEMA stated that 

road edge excursion limits for LDW and 

LKA should be aligned and 

standardized with Euro NCAP 

protocols, with GM adding that more 

stringent limits, adopted by other 

regions, have spurred customer 

complaints and system disablement due 

to the need for more aggressive systems. 

However, GM did not support all 

aspects of the Euro NCAP protocol. 

Specifically, the manufacturer, along 

with Auto Innovators, stated they do not 

support ‘‘the Euro NCAP double road 

edge lane detection’’ because it can 

cause activation on gravel roads, which 

are common in rural areas in the U.S. 

Auto Innovators also noted that dashed 

road edges are not common in the U.S. 

Additional Specifications Are Necessary 

To improve test-to-test and lab-to-lab 

repeatability/reproducibility, Tesla 

recommended that NHTSA define what 

constitutes a ‘‘road edge condition’’ and 

specify how to detect it to minimize 

varying interpretations. Auto Innovators 

and Toyota also sought clarification 

regarding the road edge test conditions, 

further stating that selection of a road 

edge should be supported by validation 

testing using vehicles that are already 

equipped with LDW/LKA technology 

that permits road edge detection. The 

commenters asserted that, unlike lane 


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427https://www.regulations.gov/comment/ 

NHTSA-2021-0002-3898. See submitted graphics. 

428Roadway alignment was unknown or not 

reported for 1 percent of fatal roadway departure 

crashes and 4 percent of roadway crashes where 

police-reported injuries occurred. 

429Roadway alignment was unknown or not 

reported for 1 percent of fatal opposite direction 

crashes and 2 percent of roadway crashes where 

police-reported injuries occurred. 

430Wiacek, C., Fikenscher, J., Forkenbrock, G., 

Mynatt, M., & Smith, P. (2017), Real-world analysis 

of fatal run-out-of-lane crashes using the National 

Motor Vehicle Crash Causation Survey to assess 

lane keeping technologies, 25th International 

Technical Conference on the Enhanced Safety of 

Vehicles, Detroit, Michigan. June 2017, Paper 

Number 17–0220. 

431 It should be noted that the paper identified 

crashes where lane markings were not present on 

the side of the departure. 

markings, which can be clearly defined 

(e.g., length, width, color, etc.), road 

edges have no quantitative definition. 

Auto Innovators added that systems 

must therefore use artificial intelligence 

to compare and classify how similar a 

captured camera image is to ‘‘prelearned’’ road edges. Like Tesla, Auto 

Innovators expressed concern regarding 

repeatability and reproducibility issues 

during testing if the road edge is not 

clearly defined. 

Toyota requested that NHTSA base 

selected road edge test conditions on 

real-world U.S. roadways, which 

through a review of 2009 NASS–CDS 

cases, showed brush, curbs, and dirt as 

the three primary surfaces involved in 

road departure crashes.427 HATCI also 

stated that NHTSA should select a 

‘‘field-representative’’ road edge that 

shows the highest safety need and 

suggested that road owners and vehicle 

manufacturers could work together to 

develop road edge specifications (e.g., 

materials, shoulders, straightness, etc.) 

so that vehicles may more easily 

identify them. TRC also stressed the 

importance of specifying the material 

for the road edge (e.g., gravel, dirt, etc.) 

and recommended a gravel road edge for 

safe test conduct, especially when a 

steering robot is used during LKA tests 

and for departures exceeding one foot 

over the road edge. Both BMW and Auto 

Innovators specifically mentioned that 

they would not approve of scenarios 

that use artificial turf to denote the road 

edge, with BMW adding that the test 

conditions should closely mirror realworld conditions. Finally, Auto 

Innovators and HATCI requested that 

NHTSA submit for public review and 

comment road edge specifications prior 

to inclusion in the applicable test 

procedure(s). 

Response to Comments and Agency 

Decisions 

Road edge departure crashes are 

common and may result in rollovers or 

collisions with fixed objects, both of 

which may have critical consequences. 

However, despite the noted frequency 

and severity of road departures on roads 

with faded or absent lane markings at 

the road’s edge, at this time, NHTSA 

will not include a road edge detection 

test in its NCAP LDW/LKA test 

procedure. 

NHTSA recognizes that Euro NCAP 

currently assesses a vehicle’s ability to 

detect a passenger-side road’s edge 

when no lane marking is present. This 

test is performed both with and without 

a driver-side lane marking. However, 

the test procedure’s road edge 

specifications are not well-defined; the 

road edge may consist of grass and/or 

gravel, or any other approved surrogate. 

As noted in Annex A of the Euro NCAP 

LSS procedure, there is no artificial road 

edge with consensus at this time. Thus, 

a variety of real road edges are used, 

each of which is different. 

It is the Agency’s belief that every 

NCAP vehicle should be assessed using 

the same test conditions to promote 

fairness and maintain the program’s 

credibility. To do so, NHTSA would 

have to select a road edge type and more 

clearly define specifications. However, 

it is currently unclear which single road 

edge type would be most appropriate. 

As noted by Toyota, a variety of realworld road edge types that drivers 

regularly encounter exist (gravel, curbs, 

brush, dirt, etc.). While the selection of 

a gravel road edge may be most 

desirable for safe test conduct, as TRC 

suggested, there is not currently data to 

suggest that this road edge type is the 

most representative. 

While the Agency is not adopting a 

road edge detection test for this NCAP 

update, given the safety need identified 

previously to address road departure 

crashes in which a line at the road’s 

edge may not be visible or present, as 

outlined in the NCAP roadmap longterm plans, NHTSA will consider 

enhanced evaluations of LKA systems in 

NCAP, including a road edge detection 

test at a future time. Prior to inclusion 

of a road edge detection test scenario, 

NHTSA must determine which road 

edge test condition(s) best represents 

road edges that drivers may encounter 

in real-world driving conditions, or 

alternatively, that which represents the 

largest number of crashes and thus may 

offer the largest safety benefit. NHTSA 

agrees with Bosch’s comment that 

adding a road edge detection test would 

encourage the availability of more 

robust LKA systems throughout the 

fleet, but the Agency does not want to 

cause unintended consequences by 

doing so before adequate test 

specifications can be developed, 

reviewed, and adopted. Prior to 

implementing any future road edge 

detection assessments, NHTSA would 

consider reducing excursing limits, as 

mentioned in an earlier section, or 

aligning excursion limits with those 

included in Euro NCAP’s test protocol, 

as GM and MEMA requested. It would 

also conduct testing with then-current 

vehicle models to validate any new test 

procedure, as Toyota and Auto 

Innovators suggested. 

12. Correlating Straight and Curved 

Road Performance 

NHTSA has only performed test track 

LKA evaluations using the straight road 

test configuration specified in Euro 

NCAP’s LSS test protocol. However, the 

Agency recognized in its March 2022 

RFC notice that a significant portion of 

road departure and opposite direction 

crashes resulting in fatalities and 

injuries occur on curved roads. A 

review of Volpe’s 2011 to 2015 data set 

showed that for road departure crashes 

where roadway alignment was known, 

37 percent of fatalities and 21 percent of 

injuries occurred on curved roads.428

For opposite direction crashes where 

roadway alignment was known, 30 

percent of fatalities and 32 percent of 

injuries occurred on curved roads.429

In NHTSA’s study of the 2005 through 

2007 fatal crashes from NMVCCS,430 an 

analysis of lane departure crashes 

occurring on curved roads 431 showed 

that LKA systems would have to 

provide sustained lateral correction (i.e., 

corrective steering) to prevent the 

vehicle from departing the travel lane. 

This differs from the smaller corrective 

steering inputs required of LKA systems 

to prevent lane departures on straight 

roads. 

In its 2022 notice, NHTSA stated that 

it is unsure how LKA performance 

observed during straight road trials 

performed on a test track would 

correlate to real-world system 

performance on curved roads. However, 

the Agency hypothesized, based on onroad performance testing experience of 

newer model year vehicles, that some 

current LKA system designs include 

provisions to address lane departures on 

curved roads. The Agency found that 

some LKA systems engage by providing 

limited operation throughout a curve 

and thus provide little (if any) safety 

benefit. Conversely, more sophisticated 

LKA systems maintain engagement 

longer and offer added directional 

authority throughout a curve. These 

latter systems may provide additional 


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safety gains because the driver has more 

time to re-engage (i.e., restore effective 

manual control of the vehicle). 

Given the real-world need to address 

lane departure crashes occurring on 

curved roads and the Agency’s 

observations of vehicle system 

performance during on-road driving, 

NHTSA expressed a desire to correlate 

LKA performance on straight roads to 

that on curved roads, if possible. 

Specifically, NHTSA sought comment 

on whether it could correlate better LKA 

system performance at higher lateral 

velocities on straight roads with better 

curved road performance. The Agency 

also solicited comment on whether it 

could assume that a vehicle that does 

not exceed the maximum excursion 

limits at higher lateral velocities on 

straight roads will have superior curved 

road performance compared to a vehicle 

that only meets the excursion limits at 

lower lateral velocities on straight roads. 

Finally, the Agency asked whether it 

could assume that the steering 

intervention while the vehicle is 

negotiating a curve is sustained long 

enough for a driver to re-engage. 

Summary of Comments 

Straight and Curved Road Correlation 

There were many commenters who 

suggested that the Agency could 

correlate better performance on straight 

roads at higher lateral velocities to that 

on curved roads. Tesla, for one, stated 

that vehicles that afford better straight 

road performance are often better at lane 

line detection, which typically 

translates to better lateral control in a 

curve and maintaining tighter and 

steadier control over the vehicle’s 

position within the lane. Another 

commenter, Rivian, suggested that lane 

line detection, not the ability to handle 

high lateral velocities, was often a 

problem for LKA systems that offer poor 

performance on curved roads. The 

commenter recommended that 

assessment of LKA performance should 

be based on relative lateral velocity to 

the lane line, not absolute lateral 

velocity. Toyota and Auto Innovators 

opined that there is a correlation, and as 

such, there would be no need to adopt 

a separate curved road test, but since the 

entities did not have data to support 

their opinion, they recommended, like 

others below, that the Agency should 

conduct additional research to 

definitively conclude that a correlation 

exists. Toyota further requested that, if 

NHTSA was to perform such research, 

it should ‘‘clarify whether the target (for 

LKS performance) is on a constant 

curve, during curve entry, or both.’’ 

There were also several commenters 

that agreed the performance may be able 

to be correlated across the two roadway 

configurations; however, a few of these 

respondents suggested that the Agency 

conduct additional research to confirm 

the strength of the correlation. Aptiv 

and CAS mentioned that banking and 

sight line restrictions due to changing 

elevations may affect LKA performance 

on curved roads, but only research to 

provide comparative test results would 

indicate how much influence these 

variables have. Bosch stated that an 

LKA system that supports high lateral 

velocities on straight roads could also 

afford better performance on curved 

roads because the system should likely 

react faster and earlier, but like Aptiv 

and CAS, they suggested NHTSA 

conduct additional research to be sure. 

Although BMW didn’t suggest 

additional research, the automaker, like 

Aptiv and CAS, referenced additional 

factors affecting curved road 

intervention (i.e., accurate detection of 

road curvature and orientation angle 

toward the lane marking) that could 

lead to performance variations 

compared to straight roads, thus making 

a relative comparison difficult. ZF 

Group additionally cited lane detection 

capability, steering controller and 

torque overlay limits, and vehicle 

weight as other variables that would 

influence results. 

GM commented that a correlation may 

be possible under limited conditions, 

such as at certain lateral velocities, but 

generally, curved road performance is 

influenced by factors like banking (i.e., 

superelevation) (as also mentioned by 

Aptiv and CAS) and surface crowning 

which can’t easily be simulated in a test 

environment and will vary based on 

design speed, curve radius, etc. 

There were also commenters, 

including Intel and FCA, who stated 

that a straight road/curved road 

correlation was not possible. FCA, like 

others, voiced that many factors, 

including speed, lateral position in the 

lane, and road curvature, affect LKA 

system performance on curved roads, 

and there is currently no reliable or 

repeatable test method to capture these 

characteristics. 

Equating Excursion at Higher Lateral 

Velocities on Straight Roads to Superior 

Performance on Curved Roads 

With respect to whether the Agency 

could assume that those vehicles that 

don’t exceed maximum excursion limits 

at higher lateral velocities on straight 

roads would have superior performance 

on curved roads compared to a vehicle 

that only meets the excursion limits at 

lower lateral velocities on straight roads, 

CAS reasoned that was not a valid 

assumption. The group cited 

influencing factors like sight line 

restrictions, road construction 

differences (e.g., elevation changes), and 

‘‘underlying additive lateral 

acceleration’’ that may affect relative 

performance. Bosch agreed that superior 

performance cannot be assumed because 

reaction time is often different in a 

curve (i.e., often later) and therefore 

system behavior may vary compared to 

that observed on a straight road. 

Driver Re-Engagement 

A few commenters opined on whether 

NHTSA could assume that LKAinduced steering intervention while a 

vehicle is negotiating a curve is 

sustained long enough for the driver to 

re-engage. Almost all respondents said 

no, that is not a safe assumption. CAS 

expressed that there are too many 

variables to be considered (i.e., speed, 

curve geometry, the ADAS warnings 

provided, and the driver response) for 

such an assumption to be made. Intel 

remarked that the steering intervention 

doesn’t end until the vehicle is parallel 

to the road lane marking (with sufficient 

margin) for a few seconds. However, in 

sharp curves, the commenter noted that 

the system torque is ‘‘limited and [it] 

will not be comfortable for the driver to 

re-engage.’’ 

Unlike the other commenters, BMW 

stated that the driver would have 

enough time to re-engage, stating that 

the system intervention will last for 

several seconds as the system attempts 

to align with the lane marking. 

Likewise, ZF Group stated that 

corrective steering is provided when the 

system detects it is entering the 

‘intervention zone,’ and it should be 

maintained throughout the curve (if the 

vehicle remains in the ‘intervention 

zone’) until it disengages once the 

vehicle is brought back into the 

appropriate position. Rivian stated LKA 

intervention should be sustained in a 

curve until a driver re-engages because 

the consequence of system deactivation 

in the middle of the curve (before driver 

re-engagement) could be dangerous. The 

commenter further stated that vehicles 

that disengage prior to reengagement by 

the driver should receive lower scores. 

Unlike the other respondents who 

said re-engagement either was or wasn’t 

possible, Bosch remarked that it is 

dependent on the system design, with 

some systems providing only a slight 

correction to the heading angle, whereas 

others guide the vehicle back to the 

center of the lane. 


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432 87 FR 13452 at 13494. 

Adoption of a Separate Curved Road 

Test 

BMW asserted it was more 

appropriate to incorporate a curved road 

test than to assess systems at high lateral 

velocities on straight roads since some 

systems may interpret a fast approach 

towards the lane marking to be an 

intentional lane change (without use of 

the turn signal) and would suppress an 

intervention accordingly. Auto 

Innovators also shared BMW’s concern 

(though they did not favor adopting a 

separate curved road assessment) and 

added that a fast or strong system 

intervention in such instances may 

affect customer satisfaction, which must 

also be considered in system design. 

ASC agreed with BMW that NHTSA 

should develop a curved road test rather 

than attempt to correlate performance. 

Advocates supported incorporation of a 

curved road test in general, since a large 

proportion of crashes, especially road 

edge departure crashes, occur on curved 

roads. 

Unlike Advocates, Rivian suggested 

that NHTSA should not adopt a curved 

road test because most lane departure 

crashes occur on straight roads 432 and 

therefore the safety need is not as great 

for curved roads. The manufacturer 

further asserted, along with IDIADA, 

that drivers tend to be more attentive on 

curved roads since they know they are 

required to steer. Because of the 

influential testing variables mentioned 

previously, GM was also not supportive 

of adopting a curved road test, relaying 

that adding test scenarios that do not 

accurately depict real-world driving 

conditions may drive LKA system 

changes to meet test requirements that 

degrade performance for real-world 

drivers, thus compelling drivers to turn 

systems off. GM further stated that 

Korean NCAP performs a curved road 

test and there is high variability in test 

results. 

Toyota and Auto Innovators also 

recommended adopting only a straight 

road test condition at this time. The 

commenters expressed concerns related 

to repeatability and reproducibility for 

curved road testing, stating that (1) lane 

departure speed, which is the key input 

to initiate and evaluate LKA system 

performance, is strongly affected by 

initial lateral offset and yaw angle, and 

(2) it would be difficult to configure the 

exact same curved lane (i.e., same curve 

radius, clothoid length, banking angle, 

lane width, etc.) at all testing locations, 

including those used by vehicle 

manufacturers for NCAP performance 

verification assessments. Similar to 

GM’s assertion regarding Korean NCAP, 

the groups also relayed that Euro NCAP 

has not adopted a curved road 

assessment because of repeatability 

concerns. 

Test labs also expressed concerns 

regarding the feasibility of curved road 

testing, with TRC cautioning that curved 

road testing requires much more space 

than straight road testing, and as such, 

testing locations are limited. Further, 

IDIADA stated that curved road 

scenarios are ‘‘extremely difficult to 

implement.’’ 

Response to Comments and Agency 

Decisions 

At this time, NHTSA cannot assume 

that LKA performance on straight roads 

correlates with that expected for curved 

roads. 

Commenters unanimously agreed that 

superior performance on curved roads 

could not be assumed for those vehicles 

that do not exceed maximum excursion 

limits at higher lateral velocities on 

straight roads. NHTSA acknowledges, as 

several commenters stated, that there 

are vehicle-specific factors like vehicle 

weight and speed, in addition to the 

vehicle’s capability for lane line 

detection, which may affect LKA system 

performance on curved roads more so 

than on straight roads. The Agency also 

recognizes commenter concerns 

surrounding system suppression and 

unintended consequences of abrupt or 

strong system interventions stemming 

from the high lateral velocities needed 

to simulate curved road conditions on 

straight roads, both of which suggest a 

correlation is impracticable. Further, the 

Agency acknowledges that most 

commenters expressed that it is 

unreasonable to assume that an LKA 

steering intervention is sustained long 

enough in a curve for a driver to reengage in the driving task. While Rivian 

acknowledged that LKA intervention 

should be sustained in a curve until a 

driver re-engages because of the 

consequences inherent to system 

deactivation in the middle of the curve 

(before driver re-engagement), most 

commenters contended that there are 

too many variables at play to have such 

assurance, with Bosch stating that it 

depends on the system design, as some 

systems may only offer a slight heading 

correction whereas others direct the 

vehicle back into the center of the lane. 

Without such assurance, it would be 

misguided for the Agency to consider a 

correlation to be a sufficient surrogate 

for an actual curved road assessment. 

Further, commenters provided mixed 

support for adopting a designated 

curved road test in NCAP. Commenters 

expressing support noted that such a 

test would be more appropriate to 

reflect true system performance. Those 

opposed cited testing feasibility 

concerns, specifically limitations posed 

by space constraints and repeatability 

and reproducibility concerns arising 

from the need to replicate the exact test 

conditions/curved lane configuration 

across all testing locations. NHTSA 

acknowledges, as many commenters 

stated, that there are numerous roadway 

characteristics that can affect curved 

road intervention, including curve 

radius, elevation changes (i.e., 

superelevation), and sight line 

restrictions, which are difficult to 

simulate in a test environment, 

especially in a reliable and repeatable 

manner. It further acknowledges GM’s 

concern that test scenarios that don’t 

accurately reflect real-world driving 

conditions may spur degradation in 

real-world LKA performance, leading to 

system deactivation and a loss of safety 

benefits. 

In consideration of commenter 

concerns, the Agency plans to initiate a 

multifaceted curved road research effort. 

As part of this research, NHTSA intends 

to: (1) review lane and road departure 

crash data to identify curve radii and 

other roadway variables (e.g., 

superelevation, lane width, etc.), vehicle 

speed, and departure timing (e.g., at 

curve entry, mid curve, or near curve 

exit); (2) identify other lane departure 

protocols, or parts of protocols, that may 

be most relevant to real-world road 

departures, particularly those related to 

curved lanes; (3) identify vehicle 

models that have LKA systems that are 

designed to prevent lane departures on 

curved roads; (4) identify next 

generation LKA systems and document 

expected functionality; and (5) perform 

pilot testing to evaluate potentially 

suitable curved road test protocols. By 

taking these steps, NHTSA hopes that it 

will be able to develop a test protocol 

that accurately simulates real-world 

lane departures on curved roads to best 

address the safety problem. After the 

research is completed, NHTSA will 

consider these enhanced evaluations of 

LKA systems in NCAP, as noted in the 

NCAP roadmap long-term plans. 

13. Increasing LKA Test Speed 

In its recent RFC notice, NHTSA 

noted that a sizeable portion of fatal 

road departure and opposite direction 

crashes occur at higher posted and 

known travel speeds. As part of its 

independent analysis of the 2011 to 

2015 FARS data set, Volpe found that, 

of those crashes where posted speed 

limits were known, 58 percent of fatal 

road departure crashes and 69 percent 

of fatal opposite direction crashes 


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433Swanson, E., Foderaro, F., Yanagisawa, M., 

Najm, W.G., & Azeredo, P. (2019, August), Statistics 

of light-vehicle pre-crash scenarios based on 2011– 

2015 national crash data (Report No. DOT HS 812 

745), Washington, DC: National Highway Traffic 

Safety Administration. 434For data where the travel speed was known, 

63 and 65 percent of the data is unknown or not 

reported in FARS for road departure and opposite 

direction crashes, respectively. For road departure 

and opposite direction crashes, respectively, 3 and 

1 percent of the posted speed data is unknown or 

not reported in FARS. 

435Swanson, E., Foderaro, F., Yanagisawa, M., 

Najm, W.G., & Azeredo, P. (2019, August), Statistics 

of light-vehicle pre-crash scenarios based on 2011– 

2015 national crash data (Report No. DOT HS 812 

745), Washington, DC: National Highway Traffic 

Safety Administration. 

436 It was unknown or not reported whether 

speeding was a contributing factor in 7 percent of 

fatal road departure crashes and 4 percent of fatal 

opposite direction crashes. 

occurred on roads with posted speeds 

exceeding 72.4 kph (45 mph).433 434

Further, the study revealed that 

speeding was a known factor in 33 

percent and 13 percent of fatal road 

departure and opposite direction 

crashes, respectively.435 436 Volpe also 

found that when travel speed was 

known, 83 percent of fatal road 

departure crashes and 74 percent of fatal 

opposite direction crashes occurred at 

known travel speeds exceeding 72.4 kph 

(45 mph). 

Since NHTSA did not have data to 

show that LKA system performance at 

Euro NCAP’s current test speed of 72 

kph (44.7 mph) would be indicative of 

system performance when tested at 

higher speeds, the Agency requested 

comment on whether it would be 

beneficial to incorporate additional, 

higher test speeds to assess the 

performance of lane keeping systems in 

NCAP, or whether the current test speed 

is sufficient to indicate performance at 

higher speeds, especially on straight 

roads. Given the findings from NHTSA’s 

LKA testing of model year 2017 and 

2019 vehicles, which showed 

differences in LKA performance at 

greater lateral velocities, the Agency 

also expressed concern about LKA 

performance at higher travel speeds 

when the vehicle first transitions from 

a straight to a curved road, since lateral 

velocity may be high in those situations. 

Summary of Comments 

Maintain Current Test Speed 

Many commenters suggested the LKA 

test speed should remain at 72.4 kph (45 

mph). ASC, BMW, and Bosch 

commented that the current NCAP test 

speed accurately evaluates LKA 

performance at higher speeds and that 

increasing the test speed was 

unnecessary. Auto Innovators agreed 

that performance at the current test 

speed is indicative of performance at 

higher test speeds, and additionally 

mentioned that performance at lower 

speeds could also be assured. Similarly, 

GM stated that the proposed 72.4 kph 

(45 mph) test speed accurately evaluates 

performance at other speeds. HATCI 

recommended that NHTSA harmonize 

with Euro NCAP’s test speed of 72 kph 

(44.7 mph), as it is representative of 

LKA performance at higher speeds and 

sufficient to address fatal road departure 

and opposite direction crashes. 

Similarly, ZF Group agreed that the 

Agency should harmonize with existing 

protocols to the extent possible. FCA 

expressed that high-speed unintentional 

lane departures occur at lower lateral 

velocities, and such events would be 

encompassed by the 0.2 m/s lateral 

velocity in the current 72.4 kph (45 

mph) LKA test such that no additional 

speed increase is necessary. On the 

other hand, Advocates expressed that 

NHTSA must have data to ‘‘indicate 

whether longitudinal velocity is 

correlated with lateral velocity and 

which of these or their interaction are 

determining factors in assessing 

performance of LKS systems.’’ The 

organization questioned whether testing 

at a lower longitudinal speed and higher 

lateral velocity is the best way to 

differentiate between systems having 

different performance. 

TRC, Auto Innovators, and GM 

referenced logistical concerns for higher 

speed test assessments. TRC stated that 

if speeds were increased, additional 

lane markings and distance would have 

to be maintained. Likewise, Auto 

Innovators and GM expressed that 

longer and wider test tracks having 

additional runoff space would be 

necessary for safe testing at higher 

speeds, and yet, such testing would 

yield similar results to those obtained at 

72 kph (44.7 mph). 

Consider Additional Test Speeds 

A few commenters, including Intel 

and CAS, favored higher test speeds to 

assess LKA system performance. 

Specifically, CAS asserted that higher 

speed testing would be a better indicator 

of LKA performance. The organization 

suggested that test speeds should be 

increased until safe performance limits 

are established, and these speed limits 

should then be communicated to 

consumers. That said, CAS also 

acknowledged that ‘‘some LKS testing is 

better than no LKS testing.’’ Like CAS, 

one public commenter recommended 

that the LKA test speed be increased to 

‘‘ensure accuracy.’’ The commenter 

mentioned that most fatal road and lane 

departure crashes occur at higher 

speeds, and at such speeds, the driver’s 

ability to react and maintain control of 

the vehicle is reduced. IDIADA stated 

that since LKA system activation occurs 

at speeds of 65 kph (40.4 mph) or 

greater, the current 72.4 kph (45 mph) 

test speed covers only the lower limit of 

system intervention. As such, the 

company suggested that the Agency 

could consider conducting testing at 

speeds up to 120 kph (74.6 mph). 

MEMA did not expressly recommend 

increasing the LKA test speeds. 

However, MEMA did mention that there 

is ‘‘no technical barrier to detecting 

lanes at a range that would reliably 

support higher LKS test speeds.’’ 

Similarly, ZF Group mentioned that 

‘‘there is no technology concern 

associated with testing at higher 

speeds.’’ Finally, Rivian suggested that 

NHTSA evaluate LKA performance at 

both higher and lower speeds to better 

assure expected performance. 

Response to Comments and Agency 

Decisions 

As mentioned earlier, NHTSA is 

adopting a test speed of 72 kph (44.7 

mph) for its LDW/LKA tests. This test 

speed aligns with many real-world road 

departure and opposite direction 

crashes and serves as an appropriate 

starting point for the Agency’s newly 

adopted lane keeping tests. The Agency 

reasons this test speed is also 

appropriate because it further promotes 

harmonization. It is the same speed 

used in Euro NCAP’s LDW, LKA, and 

ELK tests, which are comparable to 

those NHTSA is incorporating in NCAP. 

Many commenters asserted that LKA 

performance at a test speed of 72 kph 

(44.7 mph) would be sufficient to assure 

similar LKA performance at higher (and 

lower) test speeds, and therefore, adding 

additional test speeds for NCAP’s tests 

is unnecessary. However, the Agency 

hesitates to agree without additional 

research testing. It may be true, as 

Advocates suggested, that testing at a 

lower longitudinal speed and higher 

lateral velocity may not sufficiently 

differentiate between systems that have 

different performance at higher speeds. 

In this case, higher-speed tests would 

also be necessary to effectively address 

the safety problem. Conversely, it may 

be true, as FCA asserted, that a 72.4 kph 

(45 mph) LKA test is sufficient to 

address unintentional lane departure 

crashes occurring at high speeds 

because these real-world crashes occur 

at lower lateral velocities, such as those 

already included in the Agency’s test 

matrix. Unfortunately, NHTSA does not 

currently have data to indicate whether 

longitudinal velocity is correlated with 

lateral velocity, as Advocates requested, 

nor does it know the extent to which 

each of these factors influence LKA 


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system performance. It also does not 

fully understand how driver reaction 

time or the driver’s ability to maintain 

control of the vehicle as speed increases 

may influence overall LKA system 

performance or crash outcomes. As 

such, more research is needed before 

NHTSA can conclude with certainty 

whether the adopted LKA test 

conditions will be sufficient to ensure 

safety benefits at alternative test speeds, 

or whether additional test conditions 

are necessary. Regardless, because of the 

significant crash problem currently at 

hand, it is prudent to move forward 

with the adopted 72.4 kph (45 mph) SV 

speed at this time rather than wait for 

the completion of further research. 

As discussed previously, the Agency 

plans to review real-world road 

departure crash data as part of a future 

research effort. NHTSA will document 

the roadway conditions associated with 

these crashes (e.g., posted speed limits, 

roadway curvature, etc.) as well as other 

influencing factors, such as vehicle 

speed and lateral velocity. The Agency 

will consider higher speeds in future 

evaluations as well as other logistical 

concerns posed by commenters (e.g., 

longer and wider tracks). 

14. Reducing the Number of Required 

Test Conditions 

Given the Agency’s LKA test 

procedure currently contains many test 

conditions (i.e., line type and departure 

direction), NHTSA requested comment 

on whether it is necessary to perform all 

test conditions to adequately address 

the lane departure safety problem or 

whether it could instead only test only 

certain conditions to minimize test 

burden. Specifically, NHTSA sought 

comment on whether it should consider 

incorporating the test conditions for 

only one departure direction if the 

vehicle manufacturer provides test data 

to assure comparable system 

performance for the other direction or 

consider adopting only the most 

challenging test condition(s). If 

commenters preferred the latter, the 

Agency questioned which test 

condition(s) would be most appropriate. 

Summary of Comments 

Departure Directions 

NHTSA received several responses on 

whether it would be sufficient to assess 

LKA performance for only one 

departure direction (i.e., left or right), 

with both BMW and Auto Innovators 

suggesting that this could be possible. 

BMW mentioned that their internal 

assessments evaluate performance for 

both departure directions, so they could 

provide data for the direction the 

Agency chooses not to assess. However, 

Auto Innovators, GM, and Bosch 

cautioned NHTSA that identical 

performance cannot be guaranteed for 

both departure directions since not all 

LKA systems are symmetrical. Auto 

Innovators recommended that 

manufacturers attest to their vehicles’ 

symmetry if NHTSA was to eliminate 

testing on one side to reduce test 

burden. 

Bosch maintained that the Agency 

should still evaluate all conditions (e.g., 

departure directions and lane marking 

types) to ensure system robustness and 

effectiveness and consistency of test 

results. GM, ASC, and Aptiv agreed 

with the need to test both directions. In 

a similar vein to that expressed by Auto 

Innovators and Bosch, DRI and TRC also 

commented that they have observed 

different performance depending on 

departure direction. As such, TRC 

encouraged NHTSA to assess both 

directions for all test conditions, but at 

a minimum, both directions for both 

solid and dashed lines. 

Lane Line Types 

Responses received on limiting LKA 

testing to a specific lane line type(s) 

were varied. FCA and ZF Group 

asserted that LKA systems should afford 

equal performance regardless of lane 

line type, while DRI claimed that it has 

observed differing performance for 

various lane lines. GM and Toyota 

claimed the dashed lane line condition 

was more challenging for LKA systems 

since cameras detect the contrast 

between the road surface and the lane 

line paint; however, GM stated that it 

has not seen meaningful performance 

differences for the various lane line 

types. GM further stated that Euro 

NCAP reduced the number of lane lines 

assessed starting in 2023 for this reason. 

Intel suggested that the Agency assess 

LKA performance for only the dashed 

lane line to reduce test burden, whereas, 

for the reasons stated earlier, Bosch 

recommended assessing all lane line 

types. 

Minimizing Test Burden in General 

In general, Auto Innovators stated that 

NHTSA should minimize test burden by 

prioritizing those test conditions 

representing the highest real-world risk 

and harmonizing with other 

organizations where possible. Advocates 

suggested that NHTSA should 

determine the number of scenarios that 

are necessary for testing based on 

whether performance in the selected 

scenarios would be sufficient to address 

the [targeted] safety need. Likewise, 

Rivian cautioned the Agency not to 

sacrifice coverage of real-world 

conditions in an attempt to reduce test 

burden. Therefore, the company did not 

support selecting only the most 

challenging conditions in general, 

especially since, depending on the 

technology, system types may vary (i.e., 

some may be camera-only, while others 

may use radar, lidar, or be fused) and 

may thus have different challenges. 

On the other hand, Toyota stated that 

adopting the most challenging 

conditions, as NHTSA had also 

suggested, may be a viable solution to 

reduce test burden. As an example, 

Toyota suggested that if sensing for LKA 

systems becomes more difficult for 

higher lateral speeds and dashed lane 

lines, then that test condition would be 

the one adopted. CAS agreed with 

Toyota in sentiment but cautioned, like 

Advocates earlier, that if the most 

challenging test conditions do not 

actually encompass test conditions that 

are removed, the Agency risks the 

possibility that manufacturers will 

design to the test and thus safety 

benefits will be lost. 

It is for this reason (i.e., loss of safety 

benefits) that IDIADA opposed adopting 

only the most challenging test 

conditions. The test laboratory asserted 

that LKA systems may be designed to 

intervene only at high lateral speeds, 

which may be considered ‘‘worst-case,’’ 

but won’t intervene at lower speeds, 

which will only further reduce 

consumer acceptance, and thus benefits. 

IDIADA suggested adopting a reduced 

test matrix (e.g., 0.2, 0.4, 0.6 m/s lateral 

velocity) or introducing a ‘‘GRID 

approach,’’ whereby the manufacturer 

would provide all results for all tests 

required in the test matrix, but NHTSA 

would only verify testing for a subset of 

the required test conditions. 

Intel and FCA suggested a similar 

concept to IDIADA’s first suggestion, a 

reduced test matrix. The two entities 

suggested that, to reduce test burden, 

the Agency should limit the number of 

lateral velocities assessed, with FCA 

specifying that NHTSA should test the 

minimum and maximum lateral 

velocities considered. Along these lines, 

Toyota also favored ‘‘efficient’’ testing, 

whereby only those test conditions and 

trials should be performed that are 

necessary to communicate performance 

to consumers. Like FCA, the automaker 

mentioned if testing one speed can 

assure performance across a speed 

range, then only that speed should be 

tested. 

To reduce test burden, GM also 

favored reducing the number of test 

scenarios, where possible, instead of the 

number of test runs (as proposed 

separately by NHTSA). The 

manufacturer stressed that setup for a 


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437See model year 2019 LKA test data. 

different test scenario requires 

significantly more time than conducting 

additional runs. ASC suggested that 

NHTSA should not reduce the number 

of test conditions and pointed out that 

the removal of the Botts’ Dots test 

condition inherently presents a 

reduction. ZF Group was supportive, in 

general, of using manufacturer test data 

to augment NHTSA’s results for those 

test conditions not assessed by the 

Agency. The group commented that this 

should not affect NHTSA’s ability to 

provide an accurate performance 

assessment for LKA systems. 

Response to Comments and Agency 

Decisions 

Given the comments received, 

NHTSA has decided to continue testing 

both departure directions (i.e., left and 

right) and several lane line types for its 

lane keeping performance tests. As 

mentioned previously, the Agency will 

also incorporate an additional test 

scenario that is similar to Euro NCAP’s 

ELK Solid Line test. With the addition 

of this test, the Agency will conduct 

LDW/LKA assessments with dashed 

yellow, solid yellow, dashed white, and 

solid white lines, in addition to Botts’ 

Dots. This approach, which adopts two 

departure directions and several 

common lane line types, should allow 

the Agency to continue to ensure system 

effectiveness and robustness, as Bosch 

asserted, as well as coherence with test 

protocols to maintain safety benefits. 

The Agency shares concerns 

expressed by those commenters who 

contended that system performance may 

vary for each departure direction 

depending on vehicle symmetry and 

system robustness. NHTSA has 

observed performance failures in one 

departure direction but not the other 

during NCAP testing of LDW systems 

and research testing of LKA systems.437

While the Agency could use 

manufacturer data or symmetry 

attestations to limit testing to one 

departure direction to reduce test 

burden, NHTSA agrees with Bosch that 

only the Agency’s own tests will ensure 

consistency of results for consumers. 

The Agency’s testing has also shown 

LDW system failures for a particular 

lane line type but passing results for the 

others assessed, proving, contrary to 

assertions from several commenters, 

that equivalent performance is not 

guaranteed. Furthermore, while several 

commenters suggested that NHTSA 

could conduct assessments for only the 

dashed lane line condition because it is 

the most challenging for lane departure 

systems, the Agency’s LDW data has 

shown run failures for other lane line 

types as well. Notably, NHTSA has 

observed LDW run failures during Botts’ 

Dots assessments but passing results for 

all runs conducted for the dashed line 

condition. Additionally, the Agency has 

seen LDW run failures for the solid line 

conditions and passing results for the 

dashed line configuration for a given 

vehicle. Similar observations were also 

made during NHTSA’s LKA research for 

each of the model year 2019 vehicles 

tested. For a given lateral velocity, it 

was typically the case that failures were 

observed for the solid line condition but 

not the dashed line condition or vice 

versa. The Agency’s data seems to show, 

as Rivian asserted, that different lane 

departure system types may have 

different challenges. As such, there is 

merit to continuing to assess multiple 

lane line types during the Agency’s 

testing. 

Even with the addition of Euro 

NCAP’s ELK Solid Line test, NHTSA is 

taking sufficient steps to reduce test 

burden by integrating LDW and LKA 

testing and eliminating repeat trials (as 

discussed next) such that it is not 

necessary to further limit testing to 

assessments for one lane line type, 

departure direction, or, as Toyota 

suggested, lateral velocity. Only by 

retaining test conditions representing 

greater coverage of real-world situations 

will the Agency ensure that it continues 

to address the safety need, as several 

commenters requested. NHTSA also 

reasons, as mentioned for the other 

ADAS technologies included herein, 

that pursuing an incremental approach 

to increasing test stringency (i.e., that 

realized by increasing lateral velocity) 

best ensures that only those lane 

departure systems affording robust 

performance achieve passing results 

during the Agency’s testing. It is for this 

reason that the Agency does not plan to 

adopt a reduced test matrix with fewer 

lateral velocities, as several commenters 

suggested. NHTSA agrees with GM that 

conducting additional runs with slightly 

different parameters (i.e., incremented 

lateral velocity) for a given test scenario 

can be accomplished rather quickly. 

Furthermore, NHTSA expects that its 

attempt to harmonize to a large extent 

with Euro NCAP’s LSS test protocol for 

its future lane keeping tests should, as 

Auto Innovators suggested, further 

reduce burden such that this concession 

is not necessary. 

15. Number of Required Trials To Pass, 

Repeat Trials, and Pass Rate for LKA 

Similar to its request for other ADAS 

technologies proposed for adoption as 

part of this update to NCAP, the Agency 

sought feedback from commenters on an 

appropriate number of test trials to 

adopt for each LKA test condition, and 

an acceptable pass rate. 

Summary of Comments 

Comments on these topics were 

varied, with some commenters 

suggesting that only one test trial for 

each test condition was appropriate, and 

others recommending up to seven trials 

per test condition. 

Those favoring one test trial per LKA 

test condition and lateral velocity 

included TRC, IDIADA, and HATCI. 

IDIADA suggested that current systems 

are very robust such that performance is 

repeatable. They also noted that system 

robustness can be evaluated two ways— 

performing the same test many times (as 

NHTSA currently does) or performing 

many tests one time. TRC and HATCI 

mentioned that if a system did not pass 

requirements at a given test speed (i.e., 

lateral velocity), performance could be 

verified with an additional test run 

(TRC) or runs (HATCI) at that speed. 

HATCI mentioned performing seven 

runs in such instances and proposed a 

pass rate of five out of seven. TRC also 

recommended that testing cease and not 

progress through higher lateral 

velocities if poor performance is 

observed for two of three test runs. 

Some commenters (GM, Rivian, FCA, 

Toyota, and ASC), preferred 

maintaining the number of trials and 

pass rate from NCAP’s current LDW test. 

Currently, NCAP performs five trials for 

each of the LDW test conditions 

(defined by a combination of lane type 

and departure direction), and vehicles 

must pass three out of the five trials (60 

percent) for each test condition, and 20 

of the 30 trials (66 percent) overall. Both 

Rivian and GM stated five trials would 

be sufficient to assure reliability of 

system performance, and a pass rate of 

three out of five would suffice to 

address any variances in testing 

conditions. In general, GM favored 

optimizing the number of test 

conditions rather than reducing the 

number of test runs since the former 

does more to reduce overall test burden 

and the latter leads to a diminished 

understanding of system performance 

variation. However, GM also noted that 

WIP SAE J3240 is proposing four tests 

per condition and a pass rate of 75 

percent (i.e., three out of four). 

Other commenters, including Bosch, 

BMW, Tesla, and Auto Innovators, 

supported a pass rate of two out of 

three, with BMW specifying that the 

pass rate apply for each lateral velocity. 

The automaker stated that the Agency 

should accept one failed run since 

perfect system performance in the real 

world cannot be guaranteed. Tesla 


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suggested that the Agency harmonize 

test protocols with Euro NCAP, but in 

instances of failed runs, NHTSA should 

repeat the test at least two more times 

(i.e., three runs in total) to assess 

‘‘performance consistency.’’ Auto 

Innovators said that although it supports 

the current pass rate (i.e., five out of 

seven), it would also support a reduced 

pass rate of two out of three to lessen 

test burden. 

Intel expressed no preference on 

either the number of runs conducted for 

each test condition or the pass rate 

adopted for LKA testing, but suggested 

that NHTSA try to minimize test burden 

when deciding what is appropriate. CAS 

stated that NHTSA use a binomial 

distribution to determine an appropriate 

reliability and confidence so that 

consumers may know how reliable a 

technology is. Advocates opined that 

the Agency should select the number of 

trials and pass/fail criteria to ensure a 

higher level of confidence in testing to 

assure consumers that the system will 

work as intended across a wide range of 

road and line conditions, not just those 

limited conditions assessed by NHTSA 

during testing. 

Response to Comments and Agency 

Decisions 

For each LKA test condition, NHTSA 

will follow a testing approach similar to 

those it has adopted for the other ADAS 

technologies included in this notice. 

The Agency will increment the SV’s 

lateral velocity towards the lane line in 

0.1 m/s (0.3 ft./s) increments from the 

minimum lateral velocity to the 

maximum for each of the required tests 

(i.e., 0.2 m/s to 0.6 m/s (0.7 ft./s to 2.0 

ft./s)), conducting one trial for each 

required lateral velocity. In the event 

the SV fails to provide an acceptable 

LKA system intervention or fails to 

issue an LDW warning that meets the 

requirements outlined for the Agency’s 

tests, testing will cease for the test 

condition, the test scenario, and LKA 

testing overall. Vehicles must pass all 

required trial runs (i.e., one run per 

lateral velocity) for all test conditions to 

receive credit for the lane keeping tests. 

A vehicle that provides an acceptable 

LDW alert in all trials, but fails to 

produce an acceptable LKA intervention 

for a given run, will not separately 

receive credit for LDW and vice versa. 

Number of Test Trials/Repeat Trials 

Like AEB and PAEB, several 

respondents recommended that the 

Agency perform multiple trials (e.g., 

two, three, four, five, seven, etc.) for 

each LKA test variant (i.e., for each 

lateral velocity assessed for each test 

condition), often with the number of 

recommended trials varying based on 

prior results. However, NHTSA has 

made the decision to run only one valid 

trial per LKA test variant. The Agency 

concludes this decision, which aligns 

with what it has adopted for AEB and 

PAEB testing, as well as for BSW and 

BSI, is appropriate for the LKA tests as 

well. 

The adopted testing approach will 

limit test burden while ensuring a 

greater number of real-world crashes are 

represented. As mentioned, the Agency 

will assess LDW alerts for multiple 

lateral velocities instead of one, as is 

required currently. NHTSA has also 

added a modified version of Euro 

NCAP’s ELK Solid Line tests, which 

will include two additional lane 

marking types (i.e., dashed white and 

solid yellow) and double lane lines, to 

its LDW/LKA test matrix to assess 

secondary departures. While this results 

in (at most) 50 test trials overall for the 

Agency’s LKA testing, this is less than 

the number of trials that will be 

required for the Agency’s PAEB tests 

and far fewer than the number of trials 

that would be required if NHTSA were 

to adopt an approach that required five 

trials per test variant (as is currently 

specified for its LDW tests) for each of 

the 10 test conditions adopted for LKA. 

Adopting five trials per test variant, as 

some commenters suggested, would 

result in 250 total test trials for the 

Agency’s LKA testing. This would be a 

significant burden to both vehicle 

manufacturers and NHTSA and would 

prohibit the Agency from 

communicating safety information 

quickly to consumers. 

NHTSA’s decision to conduct one 

trial per test variant and discontinue 

testing upon the first instance of the 

system’s inability to satisfy the 

associated performance requirements 

limits consumer confusion and better 

instills confidence and reliability in a 

vehicle’s LDW and LKA systems. As the 

Agency has mentioned previously for 

other ADAS technologies, conducting 

repeat trials in the event the system fails 

to meet test procedural requirements— 

essentially, giving a system multiple 

opportunities to pass—may provide 

consumers with a false assurance of 

system robustness and repeatability. So, 

while BMW suggested that the Agency 

should accept a limited number of 

failures in system performance during 

testing because system performance 

cannot be guaranteed under all realworld conditions, NHTSA disagrees. An 

assessment approach that affords no 

tolerance for system error during 

controlled laboratory testing best 

assures that passing systems offer robust 

performance during real-world 

operation. 

Furthermore, while other respondents 

expressed that the Agency should 

perform multiple trials for each test 

variant to ensure system reliability, the 

Agency maintains, as it conveyed for 

other ADAS technologies prior, that it is 

appropriate to require one trial run per 

test variant instead of multiple runs to 

achieve this goal. This point was echoed 

by IDIADA in its comments. The test 

laboratory asserted that system 

robustness can be evaluated two ways— 

either the same test can be performed 

many times, or, as NHTSA intends, 

many tests can be performed one time. 

Since, as discussed earlier, NHTSA will 

increment the SV’s lateral velocity by 

0.1 m/s (0.3 ft./s) from the minimum 

lateral velocity established for each test 

condition to the maximum, the slight 

increase in lateral velocity from one trial 

to the next should effectively provide 

the same benefit of assuring reliability 

as multiple runs conducted at the same 

speed. Inconsistent systems may pass at 

one lateral velocity but will likely fail at 

another (higher) lateral velocity as the 

test stringency increases. Since a failure 

of any one run at any given lateral 

velocity for any one test condition will 

result in an overall test failure for the 

tested vehicle, NHTSA concludes its 

approach is sufficient to serve as an 

acceptable gauge of system robustness. 

The Agency’s planned test method 

affords the most balanced approach to 

ensure system reliability across a wide 

range of real-world conditions with an 

acceptable degree of confidence without 

exponentially increasing test burden, 

sacrificing program integrity, or 

introducing delays in providing 

information to consumers. 

Pass Rate 

As mentioned, NHTSA has decided to 

adopt a pass rate of 100 percent for 

NCAP’s LKA testing. This decision 

aligns with the Agency’s choice for the 

other ADAS technologies discussed 

herein. Both LDW and LKA systems 

must achieve passing results (i.e., issue 

a warning or intervention, respectively, 

to meet the associated performance 

requirements) for all adopted test 

conditions (i.e., 50 tests) to receive 

credit for lane keeping technology. By 

dictating a 100 percent pass rate, 

consumers will be able to quickly 

recognize which vehicles offer robust, 

repeatable system performance. 

The Agency has decided not to assign 

credit separately for LDW and LKA 

since the LDW and LKA requirements 

will be fundamentally linked such that 

an LDW alert will be a requirement for 

the LKA tests. Furthermore, like FCW, 


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which the Agency will similarly not 

provide separate credit, LDW is an 

existing warning technology in NCAP. 

NHTSA reasons that it is not 

appropriate to continue to assign 

separate credit to an existing warning 

system (i.e., LDW) once the 

complementary active safety system 

(i.e., LKA) is introduced. This decision 

does not pertain to BSW and BSI since 

both blind spot technologies are 

simultaneously being added to NCAP as 

part of this program update. 

Furthermore, unlike the test procedure 

requirements for FCW and AEB as well 

as LDW and LKA, which will share the 

same test scenarios, different test 

scenarios are being adopted for BSW 

and BSI technology. 

Test scenarios and conditions adopted 

for LDW/LKA testing are shown in 

Table 25. 

TABLE 25—LANE DEPARTURE WARNING (LDW)/LANE KEEPING ASSIST (LKA) ADOPTED TEST CONDITIONS

Test scenario Line type Departure 

direction 

Lateral velocity 

(m/s (ft./s)) 

Passing criteria 

Maximum SV 

excursion 

(m (ft.)) 

LDW alert 

issued 

(m (ft.)) 

Primary Departure ............................

(Single Straight Lane Line) ...............

Solid White ....................................... Left ................. 0.2 (0.7) 

0.3 (1.0) 

0.4 (1.3) 

0.5 (1.6) 

0.6 (2.0) 

-0.3 (¥1.0) 0.75 to ¥0.3 

(2.5 to ¥1.0) 

Solid White ....................................... Right .............. 0.2 (0.7) 

0.3 (1.0) 

0.4 (1.3) 

0.5 (1.6) 

0.6 (2.0) 

Dashed Yellow ................................. Left ................. 0.2 (0.7) 

0.3 (1.0) 

0.4 (1.3) 

0.5 (1.6) 

0.6 (2.0) 

Dashed Yellow ................................. Right .............. 0.2 (0.7) 

0.3 (1.0) 

0.4 (1.3) 

0.5 (1.6) 

0.6 (2.0) 

Raised Pavement Markers ............... Left ................. 0.2 (0.7) 

0.3 (1.0) 

0.4 (1.3) 

0.5 (1.6) 

0.6 (2.0) 

Raised Pavement Markers ............... Right .............. 0.2 (0.7) 

0.3 (1.0) 

0.4 (1.3) 

0.5 (1.6) 

0.6 (2.0) 

Secondary Departure ........................

(Dual Straight Lane Line) .................

Solid Yellow (L)/Dashed White (R) .. Left ................. 0.2 (0.7) 

0.3 (1.0) 

0.4 (1.3) 

0.5 (1.6) 

0.6 (2.0) 

¥0.3 (¥1.0) 0.75 to ¥0.3 

(2.5 to ¥1.0) 

Solid Yellow (L)/Dashed White (R) .. Right .............. 0.2 (0.7) 

0.3 (1.0) 

0.4 (1.3) 

0.5 (1.6) 

0.6 (2.0) 

Dashed White (L)/Solid White (R) ... Left ................. 0.2 (0.7) 

0.3 (1.0) 

0.4 (1.3) 

0.5 (1.6) 

0.6 (2.0) 

Dashed White (L)/Solid White (R) ... Right .............. 0.2 (0.7) 

0.3 (1.0) 

0.4 (1.3) 

0.5 (1.6) 

0.6 (2.0) 

16. Test Procedure Changes and 

Refinements 

The Agency also asked commenters if 

there are any aspects of NCAP’s current 

LDW or proposed LKA test procedure 

that need further refinement or 

clarification. 

Summary of Comments 

Comments on this topic were varied 

and ranged from test procedure 

clarifications to future considerations. 


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438ASTM E1337–19, Standard Test Method for 

Determining Longitudinal Peak Braking Coefficient 

(PBC) of Paved Surfaces Using Standard Reference 

Test Tire. 

Comments are grouped into general 

topics below. 

Lane Line, Environmental, and Traffic 

Conditions 

TRC, GM, Toyota, and Auto 

Innovators requested that the Agency 

clarify the lane line condition that is 

acceptable for testing to improve 

repeatability and reproducibility. The 

latter three commenters asserted that 

lane lines must be ‘‘of high quality and 

free from irregularities’’ to not affect 

detection and thus, system performance. 

Accordingly, they recommended that 

there be no coal tar, tire marks, 

shadows/reflections, or faded markings, 

while TRC additionally requested 

clarification regarding brightness 

specifications. In contrast, AASHTO 

suggested NHTSA should perform LDW 

and LKA testing using roadway 

conditions prevalent in the real world, 

including faded and undetectable lane 

markings, since lane markings undergo 

wear and tear and vary with weather 

conditions. CAS mentioned the U.S. 

typically uses double lines to separate 

vehicle travel lanes from bicycle lanes, 

whereas Europe often uses physical 

barriers to create lane separation. Given 

the rise in fatalities for cyclists, CAS 

asserted that it was necessary to assess 

U.S. roadway conditions. CAS also 

proposed that the Agency adopt tests to 

assess general system functionality 

under certain environmental conditions 

(e.g., rain, ice, fog, low sun angles, 

roadway conditions, line of sight, etc.), 

traffic conditions (e.g., congestion, 

density), or operating conditions (e.g., 

speed) and ensure that vehicles inform 

drivers via a warning when the system 

is not working. 

Test Procedure Changes 

Regarding test procedure changes, GM 

and Auto Innovators proposed that 

NHTSA harmonize conceptually with 

Euro NCAP by specifying use of a 

particular robot, e.g., the ABD SR15 

steering robot, to initiate drift during 

LKA testing. Both organizations also 

asked that NHTSA devise a procedure to 

ensure that robot friction and inertia do 

not affect system performance, as well 

as consider procedural clarifications for 

steering friction and electric power 

steering tuning. 

Rivian asked that the Agency add 

‘‘improved illustrations’’ and ‘‘diagrams 

detailing what passing each test looks 

like’’ to the LKA test procedure so that 

manufacturers may better understand 

each test scenario. 

Finally, Auto Innovators 

recommended that NHTSA adopt the 

nomenclature in SAE J3063 and the 

Clearing the Confusion: Recommended 

Common Naming for Advanced Driver 

Assistance Technologies document. 

Additional Scenarios 

Some commenters suggested test 

procedure additions. Massachusetts 

Vision Zero Coalition and Vision Zero 

Network, among others, suggested that 

the Agency should perform an 

assessment of LKA systems to ensure 

they respond appropriately to passing 

cyclists (i.e., allow a safe distance— 

minimum of three feet—between the 

vehicle and cyclist when passing). 

Similarly, the League and NACTO 

requested that the Agency conduct 

research on LDW and LKA systems to 

document their interactions with 

cyclists and pedestrians (NACTO), 

because anecdotal reports suggest that 

systems are providing unwanted 

corrections when drivers attempt to 

cross a double-yellow center line into an 

opposing traffic lane to pass a cyclist 

safely. Like other commenters, NACTO 

stated that vehicles’ LKA systems 

should provide cyclists with at least 

three feet of space while passing, as this 

is required by law in 36 states and the 

District of Columbia. 

ASC, Aptiv, and an anonymous 

commenter recommended that the 

Agency consider how to change the 

current LDW/LKA test protocol to 

evaluate lane centering systems, a 

system the groups asserted NHTSA 

should encourage. These respondents 

stated that NHTSA could likely use the 

current LDW/LKA test protocol for 

testing of lane centering systems, but 

requirements for such systems should 

be more stringent. The commenters also 

suggested that it would be ‘‘highly 

appropriate’’ to include enhanced 

curved road testing as part of a lane 

centering test procedure. ITS reasoned 

that NHTSA should include lane 

centering assist alongside the other two 

lane keeping technologies in NCAP 

because the Agency noted it, too, can 

address the same pre-crash scenarios. 

The company requested details on why 

this technology was excluded. 

Advocates recommended that the 

Agency develop tests to limit false 

positives for LDW based on the most 

frequent causes of dissatisfaction and 

non-use., based on the reported driver 

satisfaction issues with LDW and the 

frequency with which such systems are 

turned off as a result. In contrast, Aptiv 

and ASC did not support the addition 

of a false positive test for LKA systems. 

One anonymous public commenter 

stated that NHTSA should consider 

evaluating systems for how they react 

after a period of driver inactivity, 

suggesting that the Agency should have 

requirements for how long the system 

should operate without driver action 

and specify what the system should do 

in such instances (e.g., bring the vehicle 

safely to stop). 

While Auto Innovators generally 

supported harmonization with Euro 

NCAP, the group did not support 

adoption of several of the consumer 

information program’s LSS scenarios for 

U.S. NCAP’s LDW/LKA tests. In 

addition to the ELK Overtaking vehicle 

scenario already discussed previously in 

the Removal or Integration of LDW 

section, the organization recommended 

that NHTSA not include the ELK 

Oncoming vehicle scenario as well. The 

group remarked that it is similar in 

intent to NHTSA’s Oncoming Traffic 

Safety Assist (OTSA) test procedure, 

which was included in NCAP’s 

roadmap. 

Response to Comments and Agency 

Decisions 

Lane Line, Environmental, and Traffic 

Conditions 

A wide variety of road conditions 

exist across the U.S. Nonetheless, one of 

the Agency’s main objectives is to 

evaluate each vehicle model against the 

same protocol. To maintain a reasonable 

test burden, testing with multiple lane 

line and all pavement surface 

conditions that a vehicle may encounter 

is not possible. This is also a reason that 

NHTSA is unable to test general system 

functionality under multiple 

atmospheric conditions and traffic 

conditions. 

That being said, it is necessary to 

clearly specify pavement condition and 

marking qualities to ensure vehicle 

models are undergoing the same 

procedure. The Agency will maintain 

the road test surface and lane line 

markings specifications currently 

included in NCAP’s LKA draft test 

procedures. Specifically, the road test 

surface shall be a dry, uniform, solidpaved high-mu surface having no 

debris, irregularities, or undulations, 

such as loose pavement, large cracks, or 

dips. The road test surface shall produce 

a peak friction coefficient (PFC) of 1.02 

± 0.05 when measured using ASTM 

F2493 standard reference test tire when 

tested in accordance with ASTM 

Method E 1337–19 at a speed of 64.4 

kph (40 mph), without water 

delivery.438 Surface friction is a critical 

factor in testing LKA systems as 

vehicles are dynamically assessed for 

various conditions, including multiple 

lateral velocities and turns. Vehicles 


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439FMVSS No. 135, ‘‘Light vehicle brake 

systems,’’ https://www.ecfr.gov/current/title-49/ 

subtitle-B/chapter-V/part-571/subpart-B/section571.135. 

440For road departure crashes, weather 

conditions were unknown or not reported in 1 

percent of fatal crashes. Roadway surface 

conditions were unknown or not reported in 1 

percent of fatal road departure crashes and 2 

percent of road departure crashes with injuries. 

441For opposite direction crashes, weather 

conditions were unknown or not reported in 1 

percent of fatal crashes. 

442SAE J3240, Passenger Vehicle Lane Departure 

Warning, Lane Keeping Assistance, and Lane 

Centering Assistance Systems Test Procedure, 

published December 20, 2023, includes provisions 

for an LCA assessment. 

also use steering and/or braking 

maneuvers for the LKA intervention 

during testing. Thus, the presence of 

moisture will significantly change the 

measured performance of a vehicle’s 

ability to turn. A dry surface is more 

consistent and provides for greater test 

repeatability. Lane line markings shall 

have high contrast, meet U.S. DOT 

specifications, as required by the 

MUTCD, and be considered in very 

good condition. Lane marker color and 

reflectivity shall meet all applicable 

standards from the International 

Commission of Illumination (CIE) for 

color and the American Society for 

Testing and Materials (ASTM) on lane 

marker reflectance. 

With respect to environmental 

conditions, the Agency’s lane keeping 

technology tests will be performed 

when the ambient temperature is any 

temperature between 0° C (32° F) and 

40° C (104° F) and the maximum wind 

speed is no greater than 10 m/s (22 

mph). While the Agency reasons that 

lane keeping systems can operate 

acceptably at lower temperatures, the 

limiting factor is braking performance 

during LKA interventions. NHTSA has 

selected an ambient temperature range 

that matches the range specified in 

NHTSA’s safety standard for brake 

system performance.439 Excessive wind 

during testing could affect the ability of 

the SV to maintain consistent speed 

and/or lateral position. 

Tests will be conducted during 

daylight hours with an ambient 

illumination on the test surface that is 

not less than 2,000 lux, as this 

approximates the minimum light level 

on a typical roadway on an overcast 

day. In addition, to better ensure test 

repeatability, testing may not be 

performed while driving toward or away 

from the sun such that the horizontal 

angle between the sun and a vertical 

plane containing the centerline of the 

subject vehicle is less than 25 degrees 

and the solar elevation angle is less than 

15 degrees. The intensity of low-angle 

sunlight can create sensor anomalies 

that may lead to unrepeatable test 

results. Visibility (i.e., a clear field of 

view) must be 5 km (3.0 mi) or greater. 

Testing will not be run during periods 

of precipitation (i.e., rain, snow, or hail) 

or when visibility is affected by fog, 

smoke, ash, or other particulate. NHTSA 

reasons that the presence of 

precipitation could influence the 

outcome of lane keeping tests because 

wet, icy, or snow-covered pavement has 

lower friction. Conducting a test under 

those conditions also poses risks to lab 

personnel. This choice is also supported 

by crash data from 2011 to 2015 which 

shows that 91 percent of fatal and 87 

percent of injurious road departure 

crashes occurred in clear weather and 

87 percent of fatal and 81 percent of 

injurious road departure crashes 

occurred on dry roadway surfaces, on 

average, annually.440 Additionally, 

when considering opposite-direction 

crashes, 88 percent of fatal and 85 

percent of injurious crashes occurred 

during clear conditions, and 83 percent 

of fatal and 76 percent of injurious 

crashes occurred on dry roadway 

surfaces on average, annually.441

As stated in the March 2022 notice, 

LDW telltales are often present when 

the activation threshold speed, lane 

markings, and environmental conditions 

meet system requirements. These 

telltales disappear when the system is 

inoperable due to inadequate conditions 

or those which introduce too much 

uncertainty for the vehicle’s systems to 

function. Given the lack of a telltale 

indicates to the driver a change in 

system status, NHTSA chose not to 

propose a requirement that the vehicle 

issue an alert if the lane keeping system 

is not functioning. This decision will be 

upheld for this NCAP update. 

Test Procedure Changes 

The Agency will use the AB 

Dynamics SR15 steering robot for its 

LKA tests, as GM and Auto Innovators 

requested. Due to its inherent low 

inertia, low drag (i.e., friction) design, 

NHTSA concludes it is unnecessary to 

devise a procedure to ensure that 

steering robot friction and inertia do not 

affect system performance. It can also be 

installed on the steering wheel without 

removing the airbag. 

NHTSA has reviewed its LDW and 

LKA test procedures for the release of 

this final notice and has added 

descriptive language and illustrations to 

improve clarity of the procedures, as 

Rivian has requested. 

The Agency has also adopted the 

nomenclature for lane keeping systems 

in SAE J3063 and the Clearing the 

Confusion: Recommended Common 

Naming for Advanced Driver Assistance 

Technologies document, as Auto 

Innovators requested. As reflected 

throughout this notice and in the 

accompanying test procedure, the 

Agency will refer to lane keeping 

systems as Lane Keeping Assistance 

(LKA) systems. 

Additional Scenarios 

While NHTSA is not actively 

conducting research or developing test 

procedures to assess the performance of 

LDW and/or LKA systems around 

cyclists and pedestrians, in light of the 

comments received, it will consider 

doing so in the future. 

NHTSA recognizes that SAE has 

recently finalized a performance-based 

test procedure to assess LCA systems; 

however, at this time, the Agency has 

not had a chance to evaluate this 

protocol to determine its acceptability 

for adoption in NCAP.442 Even minor 

changes to its current LDW/LKA test 

protocol to make requirements more 

stringent, as ASC and Aptiv suggested, 

would require evaluation. Accordingly, 

LCA performance will not be assessed 

as part of this NCAP update. That being 

said, as noted earlier when discussing 

secondary departures after an initial 

LKA intervention, NHTSA expects that 

vehicles will continue to undergo lane 

centering design improvements even 

without a prescribed test. The Agency 

will reconsider assessing the 

performance of LCA systems in NCAP 

once it has thoroughly evaluated the 

SAE test procedure. 

Regarding false positive testing for 

lane keeping technologies, NHTSA 

maintains its previous stance that a lane 

keeping technology false positive test is 

not appropriate at this time. Concerns 

with repeatability and reproducibility 

exist currently with respect to defining 

the appropriate delineation between a 

driver who is actively steering and not 

utilizing the turn signal, such that the 

system should be suppressed, and one 

who is not, such that the intervention 

would be necessary. This delineation 

must be assured to adequately address 

consumer acceptance issues. NHTSA 

plans to conduct research to assess such 

situations, as well as others where LKA 

interventions should be suppressed, 

such as when ESC, FCW, and/or AEB is 

in operation, or when a VRU is residing 

at a 25 percent offset in the SV travel 

lane. The Agency also notes it is further 

investigating human factors involved 

during intended and unintended driver 

maneuvers for future applications. 

Nuisance alerts often occur because the 

driver’s intent to maneuver in a 


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443NHTSA has a current information collection 

under the Paperwork Reduction Act (OMB Control 

Number: 2127–0629) to obtain vehicle information 

for the general public in support of NCAP. The 

information collection requests responses from 

major motor vehicle manufacturers about the 

crashworthiness, crash avoidance, and other 

capabilities of their vehicle models. The collection 

is voluntary and conducted annually. The 

information is primarily used to provide 

information to consumers. It is used to disseminate 

safety information on http://www.nhtsa.gov/ratings 

and to address consumer inquiries as well as for 

internal agency analyses. 

particular direction does not align with 

the vehicle’s movement due to poor 

environmental/road conditions and/or 

vehicle hardware or software shortfalls 

for a particular situation. Currently, the 

Agency defines driver intent by the 

vehicle’s lateral velocity; low lateral 

velocity is meant to simulate 

unintended drift without the use of a 

turn signal. It is possible that other 

information gathered by the vehicle (i.e., 

torque on the steering wheel, steering 

rate, driver gaze, etc.) can play a role in 

determining a driver’s intent to 

maneuver, thus allowing the vehicle to 

suppress unnecessary warnings and 

activations. Data gathered may also help 

inform next steps to address concerns 

regarding driver inactivity or 

distraction, which may result in 

unintended drifting. NHTSA notes this 

human factors research is ongoing, and 

the Agency continues to monitor 

consumer complaint data related to false 

positive activations of LDW and LKA 

systems. NHTSA will consider adopting 

additional LDW/LKA tests in the future 

to address relevant safety needs if such 

tests are found to be repeatable and 

reproducible during the Agency’s 

research. 

At this time, as Auto Innovators 

requested, NHTSA is not adopting Euro 

NCAP’s ELK Overtaking vehicle or ELK 

Oncoming vehicle scenarios for NCAP’s 

LDW/LKA assessments. However, as 

indicated previously, the Overtaking 

vehicle scenarios is similar to two of the 

test scenarios adopted for the NCAP’s 

BSI assessments—the SV Lane Change 

with Constant Headway scenario and 

SV Lane Change with Closing Headway 

scenario. 

VIII. Self-Reported Data 

Currently, through the Agency’s 

approved information collection,443

vehicle manufacturers report internal 

physical test data that demonstrates 

whether the recommended ADAS 

technologies installed on their vehicle 

models pass NHTSA’s system 

performance test requirements. NHTSA 

uses this data, in conjunction with 

random verification testing, to 

determine whether each vehicle model’s 

performance meets NCAP’s 

requirements. This process, in place 

since model year 2011, has been critical 

to the successful administration of the 

program. However, as the Agency noted 

in its March 2022 RFC, there are 

challenges associated with this process. 

NHTSA has identified inconsistencies 

in vehicle manufacturers’ self-reported 

data submissions, many of which may 

stem from unfamiliarity with NCAP’s 

test procedures. To address this issue, 

NHTSA stated one approach would be 

to require all vehicle manufacturers to 

provide data from independent test 

facilities that meet criteria 

demonstrating competence in NCAP 

testing protocols. NHTSA concludes 

that this step would help the Agency 

maintain credibility and retain public 

trust in its program. 

A. NHTSA’s Proposals, Summary of 

Comments, Response to Comments, and 

Agency Decisions 

1. Self-Reported Data From Non-NHTSA 

Contracted Laboratories 

In its March 2022 RFC notice, NHTSA 

proposed to only accept self-reported 

ADAS performance data from 

designated NHTSA-contracted 

laboratories. 

Summary of Comments 

Commenters were divided on whether 

the Agency should only accept selfreported test data from NHTSA’s 

contracted test laboratories. TRC, Auto 

Innovators, Honda, GM, Mitsubishi, 

Toyota, FCA, Tesla, and Hyundai stated 

that the Agency should continue to 

accept self-reported test data from nonNHTSA contracted test laboratories, as 

restricting acceptance of data to 

NHTSA-contracted laboratories may 

increase burden and contribute to 

delays in the dispensing of information 

to the public. Honda, among others, 

cautioned that if the Agency limits 

testing to only NHTSA’s contracted test 

laboratories, there may not be sufficient 

capacity available to complete all 

required testing, especially considering 

the proposed additions to the ADAS 

testing program. Vehicle models would 

then not receive credit for having a 

NHTSA-approved ADAS technology 

despite being otherwise eligible. FCA 

noted that self-reported data is accepted 

for FMVSS compliance and should 

therefore be acceptable for NCAP as 

well. Honda further requested 

clarification regarding NHTSA’s 

statement in its March 2022 RFC that 

NHTSA will refuse data when it is not 

provided from a test facility that is 

designated as a NHTSA-contracted test 

lab or when tests are not conducted in 

accordance with NCAP’s protocols, 

noting that the Agency’s use of ‘‘or’’ was 

unclear. 

TRC, a test laboratory, offered that the 

criteria most relevant to the successful 

conducting of ADAS testing are quality 

process and management accreditation, 

facility and lane marking conditions, 

equipment condition, calibration and 

traceability, independence, and a 

positive history of performing testing. 

Mitsubishi requested that test 

laboratories be made available in other 

world regions, including Japan. 

Auto Innovators acknowledged 

NHTSA’s desire to maintain program 

credibility and proposed that this could 

still be done while allowing 

manufacturers to conduct testing at an 

in-house or third-party facility. The 

group supported the Agency’s ability to 

request test documentation and to 

review any relevant data related to the 

vehicle or test facility on a case-by-case 

basis. Tesla also suggested that NHTSA 

could request a dossier containing 

evidence of a valid ADAS test prior to 

granting credit, similar to Euro NCAP’s 

process. 

On the other hand, CAS, Bosch, 

Advocates, and a public commenter 

supported accepting self-reported test 

data only from NHTSA-contracted test 

laboratories. CAS suggested that NHTSA 

publish standards with which 

laboratories could comply and become a 

NHTSA-certified lab as well as 

standards for third-party organizations 

to audit and certify other laboratories. 

The public commenter opined that the 

Agency might consider accepting data 

from laboratories contracted for UN ECE 

testing. Bosch strongly opposed selfreported data altogether and proposed 

that tests should be conducted and/or 

contracted by an authority to ensure the 

repeatability and reproducibility of 

results. The company referred to Euro 

NCAP’s testing process, in which 

vehicle manufacturers, test laboratories, 

or a third party pays for a vehicle test, 

and one of Euro NCAP’s eight test 

laboratories must perform the testing. 

Response to Comments and Agency 

Decisions 

Regarding Honda’s request for 

clarification on its proposal, NHTSA’s 

intent was to not accept manufacturers’ 

self-reported data that is either (1) 

derived from tests that were not 

conducted in accordance with NCAP’s 

testing protocols, or (2) generated by test 

laboratories that are not contracted by 

the Agency to perform the tests in 

question, regardless of whether test 

protocols were followed. The Agency’s 

proposal differed from the current 

submission process, which allows 


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444 52 FR 31691. 

manufacturers to provide test data from 

any test laboratory if the test is deemed 

valid by the manufacturer. 

Maintaining public trust is critical 

and has been NHTSA’s long-standing 

goal for NCAP. However, NHTSA 

acknowledges that the concerns 

expressed by Honda and others 

regarding test laboratory capacity is 

credible. Delays in test scheduling will 

ultimately translate to delays in 

providing updated information to the 

American public. Due to the limited 

number of NHTSA-contracted test 

laboratories currently available, it is not 

currently practicable to require 

manufacturers to perform ADAS testing 

at NHTSA-contracted laboratories in 

order to gain NCAP ADAS credit. 

As such, the Agency has determined 

that for data gathered in response to this 

NCAP update, vehicle manufacturers 

may utilize an in-house or third-party 

facility, either in the U.S. or globally, 

provided that the test is conducted (1) 

in accordance with NCAP’s test 

procedures and (2) using U.S. 

production-level vehicles identical to 

those that could be purchased by a 

consumer at dealers’ lots in the U.S. at 

any particular time during a given 

model year. However, it should be noted 

that this decision is subject to change in 

the future. For example, when NHTSA 

completes a rulemaking to update the 

Monroney label, the Agency may 

require the use of specific laboratories to 

generate ratings data, a testing method 

already used for NCAP’s optional testing 

program. Under this provision, vehicle 

manufacturers fund desired testing 

through specified laboratories; however, 

test setup, test conduct, and data quality 

control must adhere to NHTSA’s 

protocols.444 In addition, NHTSA wants 

to be clear that vehicles failing to 

provide passing performance during the 

Agency’s assessments will not receive 

credit for the related technology, 

regardless of whether passing results 

were provided by the vehicle 

manufacturer in response to the NCAP’s 

annual data information request. 

2. Other Means To Address 

Programmatic Challenges With SelfReported Data 

The Agency requested feedback from 

the public regarding new ways to 

alleviate some of the programmatic 

challenges it has encountered with 

NCAP ADAS testing. 

Summary of Comments 

GM and ASC suggested NHTSA 

should accept virtual forms of testing 

data, including computer simulations, 

software-in-the-loop, and hardware-inthe-loop methods. GM noted that 

producing data in this way would be 

more resource efficient. ASC 

recommended allowing a combined 

submission including real and virtual 

tests, particularly upon implementation. 

Auto Innovators and HATCI suggested 

the Agency engage with vehicle 

manufacturers to provide clarity 

regarding test procedures. In particular, 

HATCI proposed that NHTSA conduct 

test procedure ‘‘workshops’’ to ensure 

that vehicle manufacturers and test 

laboratories have a common 

understanding of test conduct practices. 

Auto Innovators noted that updates to 

test procedures could be made to ensure 

more repeatable and reproducible 

results. Along those lines, GM 

supported a thorough test procedure 

development process involving the 

development of confidence intervals 

and adjustment to procedures after 

enough NHTSA-sponsored and internal 

tests are conducted. 

Consumer Reports supported efforts 

to continuously review the NHTSA 

complaints database for ADAS systems 

as well as defect investigations to 

identify situations where systems may 

be creating ‘‘a perceived or real risk’’ of 

increasing crashes rather than mitigating 

them. The group also proposed 

reviewing data for consumer acceptance 

issues, such as ADAS false activations 

in the real world. 

Response to Comments and Agency 

Decisions 

The Agency will accept only selfreported data from physical testing at 

this time. NHTSA acknowledges that 

manufacturers must gather a significant 

amount of data to receive credit for any 

of the ADAS technologies recommended 

in NCAP. However, at this time, there is 

not sufficient evidence that virtual or 

computer-generated data would 

sufficiently demonstrate that vehicle 

models meet NCAP’s ADAS 

performance requirements. 

As mentioned throughout this notice, 

NHTSA plans to closely monitor realworld data for problematic activations, 

unintended consequences, and 

consumer acceptance concerns. As 

ADAS technologies become more 

prevalent in the fleet and more complex, 

it is critical that the Agency keeps 

abreast of the changing crash landscape. 

The Agency also plans to continue its 

research efforts to make ongoing 

improvements to the program, as 

discussed in the following NCAP 

Roadmap section. 

IX. NCAP Roadmap 

In accordance with section 24213(c) 

of the BIL, the March 2022 RFC notice 

proposed a 10-year roadmap setting 

forth NHTSA’s plans to upgrade NCAP 

with mid-term plans spanning 2024 

through 2028 and long-term plans 

spanning 2024 through 2033. NHTSA 

has long-established criteria for 

evaluating safety technologies for 

inclusion in NCAP. Potential program 

updates must meet the following four 

prerequisites: (1) the update to the 

program addresses a safety need; (2) 

there are system designs that can 

mitigate the safety problem, (3) existing 

or new system designs have the 

potential to improve safety, and (4) a 

performance-based objective test 

procedure exists that can assess system 

performance. 

NHTSA uses the notice and comment 

process to seek public input on updates 

to NCAP and ensure the reasonableness 

of the time periods for NCAP changes, 

and the Agency expects this practice to 

continue. As part of the Agency’s 

development of next steps for NCAP, 

NHTSA regularly evaluates other rating 

systems from vehicle safety consumer 

information programs within the United 

States and abroad, including whether 

there are safety benefits from 

consistency with those other rating 

systems. 

In the mid-term portion of the 

roadmap, NHTSA has included only 

those technologies that are practicable 

and for which objective tests, evaluation 

criteria, and other consumer data exist. 

The mid-term potential program 

updates proposed in the 2022 NCAP 

RFC included the following: 

• Adding four ADAS technologies 

(LKA, BSW, BSI, and PAEB). 

• Updating the performance 

evaluation of current recommended 

ADAS technologies (FCW, LDW, DBS, 

and CIB). 

• Including evaluation of advanced 

lighting technologies and other ADAS 

technologies. 

• Creating a new crash avoidance 

rating system. 

• Updating the Monroney label to 

include crash avoidance rating 

information. 

• Adding a crashworthiness 

pedestrian protection testing program. 

• Adding the THOR–50M in NCAP’s 

full frontal impact crash tests and the 

WorldSID–50M in NCAP’s side impact 

barrier and side impact pole test. 

• Considering a new frontal oblique 

crash test with the advanced THOR– 

50M. 

The long-term initiatives discussed in 

the March 2022 NCAP RFC notice 


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include a variety of new technologies 

with safety potential that are not 

sufficiently mature, and thus require 

additional agency research and review. 

These include: intersection safety assist 

(intersection AEB); opposing traffic 

safety assist; and more advanced 

automatic emergency braking that 

accounts for vehicles turning right or 

left at intersections across the path of 

pedestrians, as well as bicyclists, 

motorcyclists, and other VRUs in 

applicable crash scenarios. NHTSA also 

stated its intent to explore opportunities 

to encourage the development and 

deployment of emerging technologies 

for safe driving choices such as driver 

monitoring systems for reducing 

distraction and drowsy driving, 

intelligent speed assist, alcohol 

detection systems, seat belt interlocks, 

and rear seat child reminder assist. 

The March 2022 NCAP RFC notice 

explained that while the Agency can 

reasonably anticipate when the start of 

actions may occur in the mid-term 

portion of the roadmap, many 

technologies in the long-term portion of 

the roadmap require additional 

research, test procedure development, 

and product development and maturity, 

among other factors. These factors 

prevent the Agency from providing 

more details on the anticipated start of 

action at this time. For the mid-term 

initiatives, the Agency stated that the 

completion of action and subsequent 

implementation dates are highly 

dependent upon the notice and 

comment process, among other factors. 

Specifically, the Agency stated that 

completion dates depend on the number 

and depth of the comments received in 

response to an RFC notice, along with 

any technical research necessary to 

resolve any challenging issues or 

potential policy considerations raised in 

the comments. Therefore, the March 

2022 NCAP RFC notice explained that 

the Agency cannot reasonably anticipate 

those timelines in advance. 

NHTSA requested comment on (1) 

safety opportunities or technologies in 

development that could be included in 

future roadmaps, (2) opportunities to 

benefit from collaboration or 

harmonization with other consumer 

vehicle safety information programs, 

and (3) other issues to assist with longterm planning. 

Summary of Comments 

NHTSA received numerous comments 

on the proposed roadmap. Many 

commenters expressed general support 

for the proposed NCAP roadmap, with 

industry stakeholders noting that a 

roadmap with near, mid, and long-term 

strategies for updating NCAP 

incentivizes manufacturers to prioritize 

and accelerate the most relevant and 

effective safety technologies. However, 

many commenters, including Advocates 

for Highway and Auto Safety, the 

Consumer Federation of America, and 

Auto Innovators, stated that the 

proposed NCAP roadmap lacks 

sufficient specificity on future 

timelines, dates, and required actions. 

Industry stakeholders commented that 

the roadmap did not provide 

stakeholders with enough information 

to plan for the future. Stakeholders 

requested the roadmap include 

proposed and ongoing research and 

contain target dates for key milestones, 

decision points, and implementation of 

new program items to allow automakers 

to proactively plan and develop longterm design strategies and technology 

integration. Commenters also requested 

that the NCAP roadmap timetables align 

with the three-to-five-year duration 

associated with vehicle development. 

Several industry stakeholders (Honda, 

Toyota, BMW, Mercedes-Benz, GM and 

others) requested NHTSA harmonize the 

NCAP roadmap with other global 

programs, such as Euro NCAP, with 

appropriate objective test procedures 

and evaluations tailored to the U.S. 

market. Industry stakeholders stated 

that test procedures to evaluate new 

technologies should be objective, 

measurable, repeatable, and harmonized 

with other global NCAP test procedures 

where possible. Commenters noted that 

harmonizing the NCAP roadmap with 

global NCAPs will introduce safety 

technologies to U.S. consumers more 

quickly at reduced cost to consumers 

and manufacturers. 

Commenters encouraged NHTSA to 

establish regularly scheduled 

opportunities for stakeholder 

engagement and collaboration to 

develop the NCAP roadmap. Auto 

Innovators suggested establishing a 

representative advisory panel with 

annual discussions between NHTSA 

and stakeholders to help prioritize 

initiatives in the NCAP roadmap and 

establish timelines for the roadmap. 

Commenters also suggested updating 

the NCAP roadmap every three to five 

years depending on the current field 

data, available countermeasures, and 

effectiveness and safety implications of 

the available countermeasures. 

Auto Innovators and its members 

requested that NHTSA align NCAP 

initiatives with relevant ongoing 

regulatory actions. Industry 

stakeholders recommended ensuring 

consistency between NCAP and planned 

FMVSS where possible. Specifically, 

they requested that, similar to how the 

existing NCAP is structured for 

crashworthiness, FMVSS should set the 

baseline standard for vehicle 

performance, with NCAP requirements 

evaluating safety at a level either equal 

to, or above, the baseline. Safety 

advocates stated that vehicle safety 

standards that save lives outside the 

vehicle should not be left to consumer 

choice. For example, commenters stated 

that new NCAP items, such as better 

headlamps, redesigned hoods and 

bumpers, and direct visibility should be 

included in FMVSS. 

Commenters supported NHTSA’s four 

prerequisites for inclusion of items into 

NCAP. However, industry stakeholders 

also requested that the roadmap include 

items for removal from NCAP for 

various reasons such as a parallel 

regulation already addressing the same 

target population. 

Industry stakeholders expressed 

concern that certain technologies such 

as alcohol ignition and seat belt 

interlocks may not be appropriate to 

include in or show effectiveness 

through NCAP. The stakeholders further 

explained that certain consumers may 

not voluntarily seek this type of 

technology in a vehicle purchase, and it 

may be difficult to convince the average 

consumer who refrains from driving 

under the influence or driving 

unrestrained that these technologies 

directly benefit them. In contrast, 

several safety advocates and 

organizations encouraged NHTSA to 

include testing in NCAP to mitigate the 

risk of alcohol-impaired driving, and 

limit distracted driving caused by 

infotainment systems and other sources. 

Commenters requested that NCAP 

updates include the latest safety 

technologies, including: rear crosstraffic warning and rear automatic 

braking, intersection safety assist, 

intelligent speed assist, driver 

monitoring systems (DMS), alcohol 

detection systems, and human-machine 

interaction. Several commenters 

suggested including rear seat child 

passenger detection and alert systems, 

along with bicyclist and motorcyclist 

crash avoidance and crash protection 

systems, similar to that in Euro NCAP. 

Several commenters also expressed 

concerns about vehicles with higher 

hoods and reduced direct visibility of 

pedestrians in the vicinity of these 

vehicles for the driver, requesting an 

evaluation of driver direct visibility in 

NCAP. 

Safety advocates and industry 

stakeholders requested including 

advanced lighting technologies, such as 

automatic high beam and high beam 

assist systems, in NCAP. Several 

commenters also requested enhanced 

testing scenarios in future NCAP 


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445NHTSA Advanced Anthropomorphic Test 

Devices Development and Implementation Plan, 

March 2024, https://www.nhtsa.gov/sites/nhtsa.gov/ 

files/2024-04/NHTSA-Advanced-AnthropomorphicTest-Devices-Development-Implementation-041624- 

v1-tag.pdf. 

updates for all types of crash avoidance 

technologies to reflect less-than-ideal 

conditions like low light, glare, and fog. 

Several commenters requested 

expanding the range of test dummies in 

crash tests to include dummies 

representing female occupants and older 

adults in driver and passenger seating 

positions. Additionally, commenters 

suggested that vehicle safety technology 

testing consider such factors as: micromobility, wheelchair users, bicyclists, 

and diverse human variations including 

size, shape, and skin color. Commenters 

also requested the use of advanced crash 

test dummies, (e.g., THOR–50M and 

WorldSID–50M), and the use of 

additional crash test conditions such as 

frontal oblique impacts and rear seat 

occupant protection. 

Several commenters requested the 

inclusion of vehicle communication 

systems (vehicle-to-vehicle and vehicleto-everything technologies), while other 

commenters expressed cybersecurity 

and privacy concerns with such 

systems. Some commenters focused on 

post-crash safety and requested hazard 

lighting for disabled vehicles and 

automatic crash notification. 

Response to Comments and Agency 

Decisions 

NHTSA has developed a final 

roadmap for updating NCAP in multiple 

phases for the period 2024 through 

2033. The mid-term initiatives in the 

roadmap span the period 2024–2028 

and the long-term items span the period 

2024–2033. The NCAP roadmap in this 

decision notice includes four phases for 

each NCAP initiative, along with a 

completion milestone for each phase. 

The four phases are: (1) Research phase 

if applicable, (2) Request for comment 

(RFC) phase, (3) Final decision phase, 

and (4) Implementation phase. 

The Research phase may include field 

data analysis, test procedure and 

performance criteria development, and 

evaluation of vehicle technologies and 

designs. The Research phase may also 

include rulemaking to federalize tools 

used in the test procedures, such as new 

crash test dummies. The RFC phase 

includes the development of the 

proposal and publication of the RFC 

notice. The Final decision phase 

includes review of comments received, 

responding to the comments, and the 

publication of the final decision notice. 

The final test procedures and evaluation 

criteria will be provided in the final 

decision notice. 

Depending on the comments received, 

there could be additional research 

necessary between the RFC phase and 

Final decision phase. There could also 

be overlap between the Research phase 

with the RFC and Final decision phases 

to conduct supplementary research and 

draft and publish research reports 

supporting the NCAP notice. The 

Implementation phase generally begins 

one to two calendar years after the 

publication of the Final decision notice. 

While timing details are provided in 

the roadmap, NHTSA notes that some of 

the milestone dates may need to be 

changed in the future, as the completion 

of action and subsequent 

implementation dates are highly 

dependent upon the notice and 

comment process. NHTSA plans to 

update the NCAP roadmap 

approximately every four years, with 

timelines updated accordingly. 

NHTSA asserts that the notice and 

comment process, which seeks input 

from the public on updates to NCAP, 

works well and effectively. Thus, the 

Agency intends to continue to use this 

method to solicit input from the public 

on updates to NCAP. The Agency may 

also consider a stakeholder meeting on 

updating NCAP before an update to the 

roadmap is released. 

NHTSA will continue to monitor 

vehicle technologies and field data to 

select appropriate technologies and 

vehicle features to address safety needs. 

As requested by commenters, NHTSA 

will consider appropriate areas for 

harmonizing with other global programs 

such as Euro NCAP. In evaluating 

whether harmonization is appropriate, 

the Agency will assess existing 

procedures for updates to improve 

objectivity and ensure test procedures 

are representative of real-world crash 

conditions in the U.S. The Agency will 

also ensure any proposed tests can be 

used on U.S. vehicles to assess safety 

performance, and that the tests will 

evaluate technologies and vehicle 

designs addressing a U.S. safety need. 

This roadmap outlines NHTSA’s 

plans to update NCAP in the following 

three safety programs: crashworthiness, 

crash avoidance, and VRU safety. The 

NCAP rating system will consider 

systems that could include any of the 

following combinations: (1) distinct 

ratings for each of the safety programs; 

(2) a safety rating that combines the 

three distinct ratings; (3) other options 

suggested by commenters and 

consumers. Future updates to the 

roadmap could include additional safety 

programs, evaluation of new 

technologies and vehicle design 

features, and enhanced evaluation of 

vehicle technologies and designs 

currently in NCAP. As described in its 

March 2024 response to GAO 

recommendations,445 NHTSA is focused 

on reducing fatality and injury risk for 

all motor vehicle occupants and 

addressing identified disparities 

expeditiously. NHTSA is taking several 

steps to address sex-based disparities in 

motor vehicle crash outcomes. 

Regarding requests for the use of 

expanded range of advanced crash test 

dummies and test surrogates, NHTSA 

developed and published a detailed 

plan on the development and 

implementation of advanced crash test 

dummies. This plan discusses the 

Agency’s efforts to address the 

limitations of NHTSA’s current test 

dummies to provide information 

relative to certain demographic groups, 

such as female and elderly vehicle 

occupants, and certain body regions, 

such as the lower extremities. NHTSA 

plans to incorporate advanced dummies 

into NCAP crash tests when the research 

is completed, necessary tools are 

available for implementation, and they 

meet the criteria for inclusion in NCAP. 

For example, since NHTSA has efforts 

underway to include the advanced 50th 

percentile male dummy, THOR–50M, 

into Federal regulation, the mid-term 

roadmap initiatives include using the 

THOR–50M in NCAP frontal impact 

crash tests. Since research is still 

underway regarding the advanced 5th 

percentile female dummy, THOR–05F, 

the NCAP long-term roadmap initiatives 

include adding the THOR–05F in frontal 

impact crash tests. 

Consistent with standard practice, 

NHTSA conducts ongoing evaluation of 

technological advances in 

anthropomorphic test devices available 

in global and domestic markets to 

determine whether the Agency should 

include those devices in NCAP and will 

continue to do so with respect to 

anthropomorphic test devices that 

would help address the identified sexbased disparities. 

While NHTSA primarily plans to 

update NCAP with new technologies 

and vehicle countermeasures, it will 

also consider removing existing 

evaluation programs found redundant 

due to regulations or that no longer 

effectively incentivize safety 

improvements. 

The roadmap outlined in this decision 

notice takes into consideration the 

aforementioned efforts, the input 

received from all stakeholders on the 

potential updates to NCAP, the 

readiness of the technologies, safety 


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446Though various commenters requested V2X 

technology be included in NCAP, NHTSA has not 

included it in the roadmap because of uncertainties 

in the deployment of cellular V2X technologies, the 

research needed to determine the safety potential of 

these technologies in light of other emerging 

technologies, including AEB for intersection 

crashes, and the need to develop test procedures for 

evaluating V2X technologies, including 

cybersecurity. 

447Though a number of commenters requested 

rear cross traffic warning (RCTW) be included in 

NCAP, NHTSA is not including evaluation of 

RCTW in NCAP at this time because the Agency’s 

analysis of field data indicates that current RCTW 

systems have low safety benefits and are mainly 

associated with reduction in property damage 

crashes. 

448 Detailed analysis of field data suggests that 

when controlling for various factors, including 

crash speed and restraint use, female drivers have 

a higher risk of moderate lower extremity (leg and 

foot/ankle) injuries than male drivers in frontal 

crashes. Though the THOR–50M dummy is used for 

injury assessment, the countermeasures would also 

mitigate lower extremity injuries for 50th percentile 

and larger female occupants. 

449This update would encourage 

countermeasures to reduce thoracic and abdominal 

injuries to small female occupants in side impact 

crashes. This is an interim upgrade to side impact 

protection for female occupants until the advanced 

5th percentile female side impact test dummy, 

WorldSID–05F, is included in NCAP. The inclusion 

of WorldSID–05F in NCAP is a long-term update in 

this roadmap. 

potential, and the availability of 

objective and representative test 

procedures that can be applied to the 

U.S. vehicle fleet. NHTSA’s NCAP 

roadmap for mid-term and long-term 

updates to the program are shown in 

Figures 18 and 19, respectively. This 

roadmap represents the current state of 

knowledge, and any safety opportunity 

or technology not included in this 

roadmap was omitted because it did not 

meet the four prerequisites for inclusion 

in NCAP at this time. In the next update 

to the roadmap, the addition of other 

technologies or safety programs would 

be subject to NHTSA’s four 

prerequisites for inclusion in NCAP and 

the appropriateness of the technology or 

opportunity for a consumer information 

program.446

In general, the implementation timing 

of an update in NCAP ranges from 2 to 

4 years from the time of publication of 

an RFC notice announcing the proposed 

update. 

A. Mid-Term Updates to NCAP (2024– 

2028) 

1. Updates to the Crash Avoidance 

Program 

In the near-term, NHTSA plans to 

finalize and implement the four 

additional ADAS technologies proposed 

in the 2022 NCAP RFC (LKA, BSW, BSI, 

and PAEB). NHTSA will identify 

vehicles with these recommended 

technologies by way of check marks on 

the NHTSA website starting in the 

fourth quarter of 2025 with model year 

2026 vehicles. Until a crash avoidance 

rating system is developed and 

implemented, the check mark on the 

NHTSA website will remain the primary 

way of notifying consumers of available 

crash avoidance technologies meeting 

NHTSA’s system performance criteria. 

NHTSA plans to complete research on 

rear automatic braking (RAB) 447 in 2024 

and plans to evaluate RAB systems in 

NCAP starting in the fourth quarter of 

2027 with model year 2028 vehicles. 

2. Updates to the Crashworthiness 

Program 

As noted in the March 2022 NCAP 

RFC notice, NHTSA plans to use 

advanced crash test dummies with 

enhanced biofidelity (human-like 

response to impact loads) and injury 

assessment capabilities in current crash 

testing and any additional crash tests 

considered for the program. Mid-term 

updates to NCAP’s crashworthiness 

program include: 

• Using the THOR–50M instead of the 

HIII–50M in the NCAP frontal impact 

crash tests. 

• Conducting a full-frontal rigid 

barrier crash test with the HIII–05F 

dummy in the driver seat. 

Æ Equity in crash outcomes, 

including female occupant safety, is a 

priority for NHTSA. Since the advanced 

5th percentile female frontal impact test 

dummy, THOR–05F, is currently under 

evaluation and refinement, it is not yet 

ready for implementation in NCAP 

crash tests. The THOR–05F is in the 

long-term update to NCAP in this 

roadmap. Until the THOR–05F dummy 

is implemented in NCAP, NHTSA will 

use the current HIII–05F dummy for 

assessing small female occupant risk in 

the driver seating position. 

• Including a frontal oblique crash 

test using the THOR–50M. 

Æ Given the enhanced biofidelity and 

instrumentation of the THOR–50M, 

especially for lower extremity injury 

prediction, testing with the THOR–50M 

in the frontal oblique crash test would 

help reduce the high rates of leg, foot, 

and ankle injuries seen in both females 

and males.448

• Replacing the ES–2re dummy with 

the WorldSID–50M dummy in the 

driver seat in the side impact Moving 

Deformable Barrier (MDB) crash test. 

• Including the SID–IIs chest and 

abdomen deflections to assess overall 

injury potential in both the MDB crash 

test and the side pole impact test.449

NHTSA plans to implement the 

updated crashworthiness evaluation 

described above starting in the fourth 

quarter of 2027 with model year 2028 

vehicles. Implementation of the changes 

discussed will address comments 

received pertaining to the use of 

advanced crash test dummies, including 

those representing female occupants, as 

well as the incorporation of additional 

crash test conditions capturing frontal 

oblique impacts. 

3. Updates to the VRU Safety Program 

As noted earlier, NHTSA plans to 

finalize the implementation of PAEB in 

the near term. NHTSA also plans to 

finalize in the near term the 

crashworthiness pedestrian protection 

proposed on May 26, 2023. The Agency 

will consider expanding the head 

impact test areas to include bicyclists’ 

impact areas. NHTSA will include a 

check mark on the NHTSA website for 

PAEB and vehicle designs that meet the 

performance requirements in the NCAP 

crashworthiness pedestrian protection 

tests starting in the fourth quarter of 

2025 with model year 2026 vehicles. 

In response to commenters requesting 

protection for additional VRUs, NHTSA 

has expedited its research for bicyclists 

and motorcyclists, and is currently 

developing and evaluating test 

procedures specific to the vehicle fleet 

and the crash scenarios and injury 

profiles of bicyclists and motorcyclists 

in the U.S. NHTSA plans to include 

evaluation of AEB for mitigating crashes 

with bicyclists and motorcyclists (along 

path crash scenarios) starting in the 

fourth quarter of 2027 with model year 

2028 vehicles. 

Starting in the fourth quarter of 2024 

with model year 2025 vehicles, NHTSA 

plans to provide consumers with 

information obtained from vehicle 

manufacturers related to whether a 

vehicle is equipped with direct sensing 

technology and an alert system to 

mitigate heatstroke to unattended 

children in vehicles. By providing this 

information, which will be made 

available in the ‘‘Safety Features’’ 

section of the ratings page on the 

NHTSA website, NHTSA is taking 

initial steps to address comments 

received pertaining to rear seat occupant 

protection. 

4. Rating Systems 

NHTSA intends to develop and 

propose crash avoidance and VRU 

safety rating systems, an updated 

crashworthiness rating system, and an 

overall safety rating system for each 

vehicle and seek public comment. 

NHTSA plans to develop the crash 

avoidance, crashworthiness, VRU safety, 

and overall safety rating system with the 

flexibility to allow for the addition of 

ratings of new technologies and vehicle 


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Federal Register / Vol. 89, No. 232 / Tuesday, December 3, 2024 / Notices 96079 

450Since NCAP is a consumer information 

program with voluntary participation by vehicle 

manufacturers, NHTSA needs to evaluate consumer 

acceptance of intelligent speed assist technology for 

improving occupant safety. 

451While NHTSA has accelerated research on the 

THOR–05F dummy, uncertainties remain on 

federalizing the dummy and its implementation in 

crash testing. Therefore, NHTSA is considering its 

inclusion in NCAP in the long-term phase of the 

roadmap. 

452The corresponding rulemaking action is the 

inclusion of WorldSID–05F in Part 572. 

safety countermeasures, or for the 

removal of existing ones in a way that 

would not result in significant change to 

the rating systems. The final decisions 

on the crash avoidance, 

crashworthiness, and VRU safety rating 

system including overall vehicle rating 

are planned for completion in the third 

quarter of 2025 (crash avoidance), in the 

first quarter of 2026 (crashworthiness, 

VRU, overall vehicle safety) and 

implementation in NCAP in the fourth 

quarter of 2027 beginning with model 

year 2028 vehicles. 

NHTSA is currently conducting 

consumer research on approaches to 

display the crashworthiness, crash 

avoidance, VRU safety, and overall 

vehicle rating on the Monroney label. 

NHTSA plans to complete a rulemaking 

update to the Monroney label by the 

first quarter of 2026. NHTSA also plans 

to implement the new rating system, to 

include crashworthiness, crash 

avoidance, and VRU safety on the 

Monroney label and the NHTSA 

website, beginning in the fourth quarter 

of 2027 with model year 2028 vehicles. 

B. Long-Term Updates to NCAP (2024– 

2033) 

1. Updates to the Crash Avoidance 

Program 

NHTSA plans to include in NCAP the 

assessment of advanced lighting systems 

such as automatic driving beam (ADB), 

semi-automatic beam switching (SABS), 

and lower beam headlighting. NHTSA 

plans to implement the evaluation of 

advanced headlighting systems starting 

in the fourth quarter of 2030 with model 

year 2031 vehicles. 

NHTSA will conduct research to 

assess AEB performance in intersection 

crash scenarios such as left turn across 

path and straight crossing path 

conditions. After needed research is 

completed, the Agency plans to 

consider AEB evaluation in these 

intersection crash scenarios for 

inclusion in NCAP, with possible 

implementation starting in the fourth 

quarter of 2031 with model year 2032 

vehicles. NHTSA will also consider 

further enhancement to the current 

finalized AEB evaluations by including 

additional scenarios and conditions, 

with implementation starting in the 

fourth quarter of 2032 with model year 

2033 vehicles. 

The Agency is conducting research on 

enhanced assessment of LKA systems to 

include evaluation at higher speeds, 

curved path, and/or road edge detection 

scenarios. After the research is 

completed, NHTSA will consider these 

enhanced evaluations of LKA systems in 

NCAP, with possible implementation 

starting in the fourth quarter of 2030 

with model year 2031 vehicles. NHTSA 

is postponing its research on opposing 

traffic safety assist technology due to 

low fitment of this technology in 

vehicles and will consider its inclusion 

in the next update of the roadmap. 

NHTSA is researching various safe 

driving technologies, including driver 

monitoring systems to mitigate driver 

distraction and drowsy driving, and 

intelligent speed assist to mitigate 

crashes due to speeding. NHTSA will 

consider including intelligent speed 

assist in NCAP for occupant safety when 

the research on this technology is 

completed in 2028.450 NHTSA is 

considering implementation of certain 

other safe driving technologies starting 

in the fourth quarter of 2031 with model 

year 2032 vehicles. 

2. Updates to the Crashworthiness 

Program 

NHTSA is conducting research on the 

THOR–05F crash test dummy and is 

considering replacing the HIII–5F 

dummy in crash tests with the THOR– 

05F starting the fourth quarter of 2031 

with model year 2032 vehicles. At that 

time, NHTSA also plans to evaluate rear 

seat occupant protection using the 

THOR–05F, which will seek to address 

comments received regarding this 

topic.451

NHTSA is still developing and 

evaluating the WorldSID–05F dummy 

and will consider its adoption into 

NCAP when research and rulemaking 

actions 452 are complete. The Agency is 

considering replacing the SID–IIs 

dummy with the WorldSID–05F dummy 

in NCAP tests starting in the fourth 

quarter of 2033 with model year 2034 

vehicles. 

As part of these efforts, NHTSA will 

also consider applying different injury 

criteria to data collected from the crash 

tests utilizing these new dummies to 

target performance thresholds that are 

more appropriate for older adults to 

address broader equity concerns. 

3. Updates to the VRU Safety Program 

NHTSA plans to enhance AEB 

evaluation by including intersection 

crash scenarios (e.g., crossing path, left 

turn across path) for bicyclists and 

motorcyclists, with implementation 

starting in the fourth quarter of 2030 

with model year 2031 vehicles. NHTSA 

will also consider further enhancement 

to the current finalized PAEB 

evaluations to incorporate additional 

test speeds, test scenarios, and VRUs 

(such as those representing wheelchairs, 

scooters, and diverse human attributes), 

with implementation starting in the 

fourth quarter of 2032 with model year 

2033 vehicles. 

NHTSA also plans to evaluate BSW 

and BSI to mitigate crashes with 

motorcyclists and bicyclists in multiple 

scenarios, with implementation starting 

in the fourth quarter of 2030 with model 

year 2031 vehicles. 

NHTSA plans to evaluate and include 

the advanced pedestrian legform 

impactor (aPLI, a newer pedestrian 

legform impactor with upper body mass 

and enhanced injury assessment 

capabilities), to assess crashworthiness 

pedestrian protection instead of the 

current FlexPLI (a flexible pedestrian 

legform impactor which lacks upper 

body mass). This VRU safety program 

update will be implemented starting in 

the fourth quarter of 2029 with model 

year 2030 vehicles. 

NHTSA is researching driver visibility 

to better understand the safety problem 

and scenarios associated with forward 

blind zones and front-over crashes to 

develop accurate and rigorous methods 

of evaluating driver’s visibility. After 

the research is completed, NHTSA will 

consider inclusion of driver visibility in 

NCAP. 

By pursuing these efforts, the Agency 

will continue to work towards 

protecting those inside and outside the 

vehicle, as encouraged by public 

comments. 

NHTSA’s NCAP roadmaps for midterm and long-term updates to the 

program are shown in Figures 18 and 

19, respectively. In these two figures, 

the timeframe of the research, RFC, and 

final decision phases are in calendar 

years. The start of the implementation 

phase, represented by a star, is with 

vehicle models of the proceeding 

calendar year. 

BILLING CODE 4910–59–P 


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Figure 18: Roadmap for Mid-Term Upgrades to NCAP 

Roadmap for Mid-Term Potential Updates to NCAP Evaluations 

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II RfC Phase • >;. Implementation - NCAP safely information available to the public beginn
96082 Federal Register / Vol. 89, No. 232 / Tuesday, December 3, 2024 / Notices 

453Highway Loss Data Institute. (2023). Predicted 

availability of safety features on registered 

vehicles—a 2023 update. Loss Bulletin, 40(2). 

454 ‘‘Road vehicles—Test devices for target 

vehicles, vulnerable road users and other objects, 

for assessment of active safety functions—Part 3: 

BILLING CODE 4910–59–C 

X. Economic Analysis 

The various changes in NCAP 

adopted in this final decision notice 

would enable the development of a new 

set of rating systems, which will expand 

the current rating system to include not 

only crashworthiness but also crash 

avoidance information and improve 

consumer awareness of ADAS safety 

features as well as encourage 

manufacturers to accelerate their 

adoption. This increased information to 

consumers and potential for accelerated 

adoption of ADAS would drive any 

economic and societal impacts that 

result from these changes and are thus 

the focus of this discussion of economic 

analysis. Hence, the Agency has 

considered the potential economic 

effects for ADAS technologies proposed 

for inclusion in NCAP and the potential 

benefit of introducing a rating system 

for ADAS technologies. 

Unlike crashworthiness safety 

features, where safety improvements are 

attributable to improved occupant 

protection when a crash occurs, the 

impact that ADAS technologies have on 

fatality and injury rates is a direct 

function of their effectiveness in 

preventing crashes or reducing the 

severity of the crashes they are designed 

to mitigate. This effectiveness is 

typically measured by using real-world 

statistical data, laboratory testing, or 

Agency expertise. 

With respect to vehicle safety, the 

Agency concludes, as discussed in 

detail in this notice, the adopted ADAS 

technologies have the potential to 

reduce vehicle crashes and crash 

severity. As cited in the RFC notice, 

researchers have conducted preliminary 

studies to estimate the effectiveness of 

ADAS technologies. Although these 

studies have been limited to certain 

models or manufacturers, which may 

not represent the entire fleet, they 

illustrate how these systems can provide 

safety benefits. Thus, although the 

Agency does not have sufficient data to 

determine the monetized safety impacts 

resulting from these technologies in a 

way similar to that frequently done for 

mandated technologies, when compared 

to the future without the proposed 

update to NCAP, NHTSA expects that 

these changes would likely have 

substantial positive safety effects by 

promoting earlier and more widespread 

deployment of these technologies. 

NCAP also helps address the issue of 

asymmetric information (i.e., when one 

party in a transaction is in possession of 

more information than the other), which 

can be considered a market failure. 

Regarding consumer information, the 

introduction of an upcoming new ADAS 

rating system is anticipated to provide 

consumers additional vehicle safety 

information (e.g., rating based on ADAS 

performance and capability as well as 

the types of ADAS in vehicles) as 

opposed to the information provided in 

the current program (e.g., check mark 

based on ADAS performance as pass/ 

fail) to help them make more informed 

purchasing decisions by better 

presenting the performance of different 

ADAS technologies. The future ADAS 

rating would increase consumer 

awareness and understanding of the 

safety benefits in these technologies, 

and, in turn, incentivize vehicle 

manufacturers to offer the ADAS 

technologies that lead to higher ratings 

across a broader selection of their 

vehicles. Furthermore, as these ADAS 

technologies mature and become more 

reliable and efficient, a large portion of 

vehicles equipped with such systems 

would achieve higher ADAS ratings, 

and in turn consumers would have an 

increasing number of safer vehicles to 

choose from. There is an unquantifiable 

value to consumers in receiving 

accurate and comparable information 

about the safety performance of those 

technologies among manufacturers, 

makes, and models. 

IIHS/HLDI predicted that the number 

of vehicles equipped with ADAS 

technologies, including blind spot 

warning and lane departure warning, 

will increase substantially from 2020 to 

2030 and reach near full market 

penetration in 2050.453 Although the 

Agency has limited data on costs of 

ADAS technologies to consumers, 

assuming consumer demand for safety 

remains high, the future ADAS rating 

system would likely accelerate the full 

adaptation of the ADAS technologies 

included in this notice. Nevertheless, 

the Agency does not have sufficient 

data, such as unit cost and information 

on how quickly full adaptation might be 

reached once an ADAS rating system is 

implemented, to predict the net increase 

in cost to consumers with a high degree 

of certainty. 

XI. Appendix 

The Agency’s final decision for AEB 

and PAEB testing in NCAP is generally 

similar to the standards for those 

technologies contained in the May 9, 

2024, final rule establishing FMVSS No. 

127. The two standards are based on the 

Agency’s separate authorities and are 

intended to serve the distinct purposes 

of NCAP and the FMVSS. The Agency 

provides the below summary to assist 

readers in understanding the key areas 

of similarity and difference. 

With regard to vehicle AEB, the 

minimum and maximum subject vehicle 

(SV) test speeds and principal other 

vehicle (POV) test speeds for lead 

vehicle stopped (LVS), lead vehicle 

moving (LVM), and lead vehicle 

decelerating (LVD) crash imminent 

braking (CIB) and dynamic brake 

support (DBS) tests (as applicable) are 

the same in both NCAP and FMVSS No. 

127, except for the minimum SV test 

speed for the LVS CIB test. For this LVS 

CIB test, the Agency has prescribed a 

minimum SV test speed of 40 kph (24.9 

mph) for NCAP, whereas a 10 kph (6.2 

mph) minimum speed is specified in 

FMVSS No. 127. Further, both FMVSS 

No. 127 and NCAP impose a test passing 

criterion of ‘‘no contact’’ and stipulate 

conducting only one trial per test 

condition. Other specifications 

pertaining to test conduct such as SV 

accelerator pedal release timing and 

manual brake application timing are 

also identical for NCAP and FMVSS No. 

127. 

There are various differences that 

exist with respect to the testing 

methods. For a given NCAP test 

scenario, the Agency will begin testing 

at the minimum prescribed test speed 

and will increase the test speed in 10 

kph (6.2 mph) increments until the 

maximum test speed is reached. In 

comparison, FMVSS No. 127 permits 

testing at any speed within the speed 

range defined by the minimum and 

maximum test speeds. Similarly, for the 

LVD tests, NCAP and FMVSS No. 127 

both establish minimum and maximum 

headways between 12 and 40 m (39.4 

and 131.2 ft.) and POV deceleration 

between 0.3 and 0.5g, but NCAP will 

only conduct tests at those minimum 

and maximum values, while the FMVSS 

No. 127 permits testing at any headway 

within the range. 

In addition, while both FMVSS No. 

127 and NCAP will evaluate FCW 

functionality during AEB testing, and 

the requirements for the timing of the 

FCW alert as well as the necessary alert 

modalities (i.e., visual and auditory 

signals) are identical, FMVSS No. 127 

imposes additional FCW alert 

specifications, including auditory signal 

intensity and visual symbol color and 

location requirements. Further, FMVSS 

No. 127 allows for a wider variety of 

vehicle test devices, as any device that 

complies with certain specifications 

defined in ISO 19206–3:2021 454 is 


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Requirements for passenger vehicle 3D targets, 

Edition 1, 2021–05.’’ 

permitted, whereas the Agency has 

adopted a particular device (Revision G 

of the ABD GVT) that meets the 

requirements of the ISO standard for 

NCAP’s AEB testing. Finally, the passthrough false positive test is included in 

FMVSS No. 127 but has not been 

adopted for NCAP. 

Many of the PAEB testing 

requirements adopted for FMVSS No. 

127 are also identical to those adopted 

for NCAP. In particular, the same test 

scenarios and pedestrian test 

mannequins are specified for the two 

initiatives, and the mannequin travel 

speeds align for all test conditions. 

Minimum and maximum SV speeds are 

also the same for test conditions S1a, 

S1b, S1e, and S4c during daylight 

testing and for S1b and S4c during 

darkness testing. 

For other test conditions, though, the 

minimum and maximum SV travel 

speeds for the FMVSS and NCAP do not 

align. In particular, for daylight testing, 

NCAP imposes an upper test speed of 60 

kph (37.3 mph) for the S1d test 

condition, whereas FMVSS No. 127 has 

established an upper test speed of 50 

kph (31.1 mph). Similarly, for S4a, 

NCAP has adopted a maximum test 

speed of 60 kph (37.3 mph), whereas 55 

kph (34.2 mph) has been adopted in 

FMVSS No. 127. For darkness testing, 

NCAP has established a maximum test 

speed of 60 kph (37.3 mph) for the S4a 

test condition, whereas FMVSS No. 127 

specifies an upper test speed of 55 kph 

(34.2 mph) for this test condition. 

FMVSS No. 127 has also imposed 65 

kph (40.3 mph) as the upper test speed 

for S4c, while NCAP has adopted a 

maximum test speed of 60 kph (37.3 

mph) for this test condition. 

Other differences between FMVSS 

No. 127 and NCAP’s PAEB testing 

requirements exist for darkness testing. 

While NCAP, like FMVSS No. 127, will 

require testing in darkness, NCAP will 

not conduct separate performance 

assessments for both the SV’s lower and 

upper beam headlamps and, instead, 

will only engage the vehicle’s lower 

beams. Furthermore, FMVSS No. 127 

does not require darkness testing for 

PAEB test conditions S1a, S1d, and S1e, 

whereas such testing is specified for 

NCAP. 

The overall test requirements and test 

conduct for PAEB are also in general 

alignment, as both FMVSS No. 127 and 

NCAP include a passing criterion of ‘‘no 

contact’’ and stipulate conducting only 

one trial per test condition. As with 

vehicle AEB, though, for a given NCAP 

test scenario, the Agency will begin 

testing at the minimum prescribed test 

speed and will then increase the test 

speed in 10 kph (6.2 mph) increments 

until the maximum test speed is 

reached, while FMVSS No. 127 permits 

testing at any speed within the speed 

range. 

Issued in Washington, DC, under authority 

delegated in 49 CFR 1.95 and 501. 

Adam Raviv, 

Chief Counsel. 

[FR Doc. 2024–27447 Filed 12–2–24; 8:45 am] 

BILLING CODE 4910–59–P 


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