390 Federal Register / Vol. 90, No. 2 / Friday, January 3, 2025 / Rules and Regulations 

DEPARTMENT OF TRANSPORTATION 

National Highway Traffic Safety 

Administration 

49 CFR Part 571 

[Docket No. NHTSA–2024–0071] 

RIN 2127–AL37 

Federal Motor Vehicle Safety 

Standards; Occupant Crash 

Protection, Seat Belt Reminder 

Systems, Controls and Displays 

AGENCY: National Highway Traffic 

Safety Administration (NHTSA), 

Department of Transportation (DOT). 

ACTION: Final rule. 

SUMMARY: This document amends 

Federal Motor Vehicle Safety Standard 

(FMVSS) No. 208, ‘‘Occupant crash 

protection,’’ to require a seat belt use 

warning system for rear seats. The rule 

also updates and enhances the current 

seat belt warning requirements for the 

driver’s seat belt and extends these 

requirements to the front outboard 

passenger seat. The final rule applies 

(with some exceptions) to passenger 

cars, trucks, most buses, and 

multipurpose passenger vehicles with a 

gross vehicle weight rating of 4,536 

kilograms (10,000 pounds) or less. This 

document also makes related 

amendments to FMVSS No. 101, 

‘‘Controls and displays.’’ 

DATES: Effective date: The effective date 

of this final rule is March 4, 2025. 

Compliance date: The compliance 

date of this final rule is September 1, 

2026, for the front seat belt warning 

system requirements and September 1, 

2027, for the rear seat belt warning 

system requirements, with optional 

early compliance permitted. Multi-stage 

manufacturers and alterers would have 

an additional year to comply. 

Petitions for reconsideration: Petitions 

for reconsideration of this final rule 

must be received not later than February 

18, 2025. 

ADDRESSES: Petitions for reconsideration 

of this final rule must refer to the docket 

and notice number set forth above and 

be submitted to the Administrator, 

National Highway Traffic Safety 

Administration, 1200 New Jersey 

Avenue SE, Washington, DC 20590. 

Note that all petitions received will be 

posted without change to 

www.regulations.gov, including any 

personal information provided. 

Privacy Act: Petitions will be placed 

in the docket. Anyone is able to search 

the electronic form of all documents 

received into any of our dockets by the 

name of the individual submitting the 

comment (or signing the comment, if 

submitted on behalf of an association, 

business, labor union, etc.). You may 

review DOT’s complete Privacy Act 

Statement in the Federal Register 

published on April 11, 2000 (Volume 

65, Number 70; Pages 19477–78) or you 

may visit https://

www.transportation.gov/individuals/ 

privacy/privacy-act-system-recordsnotices. 

FOR FURTHER INFORMATION CONTACT: For 

non-legal issues, you may contact Ms. 

Carla Rush, Office of Crashworthiness 

Standards, Telephone: (202) 366–4583; 

Email: carla.rush@dot.gov; Facsimile: 

(202) 493–2739. For legal issues, you 

may contact Mr. John Piazza 

(John.Piazza@dot.gov) or Eli Wachtel 

(Eli.Wachtel@dot.gov), Office of Chief 

Counsel, Telephone: (202) 366–2992; 

Facsimile: (202) 366–3820. The address 

of these officials is: the National 

Highway Traffic Safety Administration, 

1200 New Jersey Avenue SE, 

Washington, DC, 20590. 

SUPPLEMENTARY INFORMATION: 

Table of Contents 

I. Executive Summary 

II. Background 

III. Other Seat Belt Reminder Requirements 

and Protocols 

IV. Statutory Authority 

V. Summary of the NPRM 

VI. Final Rule and Response to Comments 

A. Rear Seat Belt Warning Requirements 

1. Applicability 

2. Requirements 

a. Visual Warning on Vehicle Start-Up 

i. Type of Information Conveyed by the 

Visual Warning and Whether Occupant 

Detection Should Be Required 

ii. Lack of an Audible Warning 

iii. Triggering Conditions for Start-of-Trip 

Warning (Not Including Occupant 

Detection Criteria) 

iv. Seat Occupancy Criteria and Interaction 

With Child Restraint Systems 

v. Duration 

vi. Other Aspects 

b. Audio-Visual Change-of-Status Warning 

c. Electrical Connections/Removable Seats 

d. Owner’s Manual Instructions 

e. Telltale Location 

3. Alternative Warning Signals 

B. Front Seat Belt Warning Requirements 

1. Applicability 

2. Driver’s Seat Belt Warning for Light 

Buses 

3. Visual and Audible Warning Duration 

and Activation 

4. Visibility of Visual Warning for Front 

Outboard Passenger Seat Belt 

5. Front Seat Occupant Detection and Seat 

Occupancy Criteria 

C. Issues Common to the Front and Rear 

Seat Belt Warning Requirements 

1. Modification of Start-of-Trip Warning 

Trigger Related Ignition Switch Position 

To Accommodate EVs 

2. Belt Use Criteria 

3. Visual Warning Characteristics 

4. Interaction With Other Vehicle Warnings 

5. Audible Warning Characteristics (Other 

Than Duration) 

6. Warning Deactivation and 

Acknowledgement and Hardening 

7. Vehicles With Automated Driving 

Systems 

8. Test Procedures 

VII. Regulatory Alternatives 

VIII. Overview of Benefits and Costs 

A. Final Rule Requirements 

1. Rear Seat Belt Warning System 

2. Front Seat Belt Warning System 

3. Overall Benefits and Costs of the Final 

Rule 

B. Regulatory Alternatives 

1. Occupant Detection in Rear Seats 

2. 90-Second Front Outboard Seat Belt 

Warning 

3. Seat Belt Warning for Front Center Seat 

IX. Compliance Dates 

X. Regulatory Analyses 

Appendix A. List of Comments Cited in 

Preamble 

I. Executive Summary 

This final rule amends Federal Motor 

Vehicle Safety Standard (FMVSS or 

Standard) No. 208, ‘‘Occupant crash 

protection,’’ to require a seat belt use 

warning system for rear seats. This rule 

completes NHTSA’s response to a 

mandate in the Moving Ahead for 

Progress in the 21st Century Act (MAP– 

21) that directed NHTSA to initiate a 

rulemaking to require a seat belt 

warning for the rear seats in motor 

vehicles; it also completes NHTSA’s 

action on a rulemaking petition from 

Public Citizen and Advocates for 

Highway and Auto Safety for the same 

rule. The final rule also updates and 

enhances the current seat belt warning 

requirements for the driver’s seat belt 

and extends these requirements to the 

front outboard passenger seat. The final 

rule applies (with some exceptions) to 

passenger cars, trucks, most buses, and 

multipurpose passenger vehicles 

(MPVs) with a gross vehicle weight 

rating (GVWR) of 4,536 kilograms 

(10,000 pounds) or less. NHTSA is 

issuing this final rule under the 

National Traffic and Motor Vehicle 

Safety Act (Safety Act), 49 U.S.C. 

chapter 301, Motor Vehicle Safety (49 

U.S.C. 30101 et seq.). 

Safety Need for the Final Rule 

Using a seat belt is one of the most 

effective ways a motor vehicle occupant 

can prevent death and injury in a crash. 

Seat belts prevent occupants from being 

ejected from the vehicle, provide ‘‘ridedown’’ by gradually decelerating the 

occupant as the vehicle deforms and 

absorbs energy, and reduce occupant 

contact with harmful interior surfaces 

and other occupants. Seat belts are 

effective in most types of crashes and 


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greatly reduce the risk of fatal and nonfatal injuries compared to the risk faced 

by unrestrained occupants. 

While seat belt use is meaningfully 

higher than it was a decade ago, there 

is room for improvement. Usage rates 

for seat belts in rear seats have 

consistently been below those for the 

front seats; and while front seat belt use 

rates increased in the early 2010s, for 

the last several years they have 

plateaued. According to data from 

NHTSA’s annual study of observed seat 

belt use, in every year from 2013 

through 2022, seat belt use was lower in 

the rear seats than in the front seats, 

ranging from a difference of about 9 

percentage points in 2013 (78 percent 

vs. 87 percent) to about 14 percentage 

points in 2017 (75 percent vs. 89 

percent). In 2022, front seat belt use was 

about 91.6 percent and rear seat belt use 

was about 81.7 percent. 

Every year, thousands of unrestrained 

motor vehicle occupants are killed in 

crashes and tens of thousands of 

unrestrained occupants are injured 

(additional details on the target 

population are provided in the summary 

of benefits and costs later in this 

executive summary). Seat belt warning 

systems (also referred to as seat belt 

reminder systems) encourage seat belt 

use by reminding unbuckled occupants 

to fasten their belts and/or by informing 

the driver that a passenger is unbelted 

so that the driver can request the 

unbelted occupant to buckle up. The 

warnings provided by seat belt warning 

systems typically consist of visual and/ 

or audible signals. Research by NHTSA 

and others shows that seat belt warning 

systems are effective at getting 

unbuckled occupants to fasten their seat 

belts. 

FMVSS No. 208 currently requires a 

short-duration audio-visual seat belt 

warning for the driver’s seat belt in 

passenger cars, most trucks and MPVs 

with a GVWR of 4,536 kg (10,000 lb) or 

less, and buses with a GVWR of 3,855 

kg (8,500 lb) or less. Under these current 

requirements, the visual component of 

the warning generally must be at least 

60 seconds long, and the audible 

component must be at least four seconds 

long. 

Voluntary adoption by vehicle 

manufacturers of warnings that go 

beyond this regulatory minimum, while 

considerable, has been mixed. Although 

the regulations do not require seat belt 

warnings for any seating position other 

than the driver’s seat, almost all model 

year (MY) 2022 vehicles have a 

voluntarily provided seat belt warning 

for the front outboard passenger seat. 

However, voluntary adoption for rear 

seats has been much slower, as only 

about 47 percent of MY 2022 vehicles 

come equipped with a voluntarily 

provided rear seat belt warning system. 

Most vehicles already provide a seat belt 

warning for both front outboard seats 

that is much longer than the minimal 

required warning for the driver’s seat 

belt, with the vast majority of vehicles 

including an alert that is at least 90 

seconds. This widespread adoption 

suggests that the front seat belt warning 

minimum requirements in the FMVSS 

are outdated, as consumers accept 

audio-visual reminders that are far 

longer than the required minimums. 

As discussed above, rear seat belt use 

rates have persistently been below those 

for the front seats, and progress on front 

seat belt use rates has slowed. Moreover, 

unbuckled occupants, in the front and 

rear seats, continue to be 

overrepresented in fatal crashes (51 

percent), given the lower exposure of 

unbelted occupants relative to belted 

occupants (because front seat belt use is 

about 90 percent and rear seat belt use 

is 80 percent). Despite the effectiveness 

of seat belts and seat belt warnings, 

most new vehicles continue to lack a 

rear seat belt warning. Additionally, 

while most vehicles provide some level 

of enhanced reminders for the front 

seats, this level of enhanced protection 

has not occurred for all vehicles and is 

not standardized. This gap in protection 

suggests a need for a beneficial safety 

technology that is not being met in the 

vehicle market. This final rule is 

intended to meet this safety need. 

Legal Authority and Prior Regulatory 

History 

NHTSA is issuing this final rule 

pursuant to the National Traffic and 

Motor Vehicle Safety Act (49 U.S.C. 

30101 et seq.) (Safety Act), which 

authorizes NHTSA to establish FMVSSs. 

That statute requires safety standards to 

be objective, practicable, and meet the 

need for safety, among other things. 

NHTSA has concluded that the finalized 

requirements satisfy these statutory 

criteria. 

This final rule completes NHTSA’s 

response to a rulemaking mandate in 

MAP–21. MAP–21 required DOT 

(NHTSA, by delegation) to initiate a 

rulemaking proceeding to require rear 

seat belt warnings and directed the 

agency to issue a final rule unless the 

rule would not meet the Safety Act 

requirements for an FMVSS. 

This final rule also completes 

NHTSA’s action on a rulemaking 

petition from Public Citizen and 

Advocates for Highway and Auto Safety. 

The petition requested that NHTSA 

issue a rule requiring a seat belt warning 

system for rear seats on passenger cars 

and MPVs with a GVWR of 4,536 kg 

(10,000 lb) or less. 

Summary of the Final Rule 

This final rule amends the existing 

seat belt warning provisions in FMVSS 

No. 208. The final rule has two main 

components. The first requires a seat 

belt warning for the rear seats. The 

second amends and enhances the seat 

belt warning requirements for the front 

outboard seats. The requirements apply 

(with some exceptions) to passenger 

cars and trucks, most buses, and 

multipurpose passenger vehicles with a 

GVWR of 4,536 kg (10,000 lb) or less. 

1. Rear Seat Belt Reminder 

Requirements 

The first component of this final rule 

is a set of requirements for a seat belt 

warning for rear seats. The new 

requirements have four main elements. 

• Visual warning on vehicle start-up 

to inform the driver of the status of the 

rear seat belts. The final rule requires a 

visual warning that informs the driver 

how many or which rear seat belts are 

in use and/or not in use. The warning 

must activate when the ignition (or, for 

electric vehicles (EVs), propulsion 

system) is activated, and last for at least 

60 seconds. No visual warning is 

required if the system can determine 

that there are no occupied rear seats or 

if there are no occupied rear seats with 

a seat belt that is not in use. 

• Audio-visual change-of-status 

warning. The final rule requires an 

audio-visual warning whenever a 

fastened rear seat belt is unfastened 

while the vehicle is in forward or 

reverse drive mode. (The warning is not 

required if the system can determine 

that a rear passenger has unfastened the 

seat belt in order to exit the vehicle or 

switch seats.) The warning must last for 

at least 30 seconds or until the seat belt 

that triggered the warning is re-fastened. 

The audible portion of the warning may 

be temporarily paused to allow another 

audible safety warning alerting the 

driver to take immediate action. 

• Requirements related to electrical 

connections. Readily removable rear 

seats must either automatically establish 

the electrical connections when the seat 

is put in place or, if a manual 

connection is required, the connectors 

must be readily accessible. Vehicles 

equipped with certain types of seat belt 

warning systems are additionally 

required to provide a visual warning to 

the driver if a proper electrical 

connection has not been established. 

• Owner’s manual requirements. The 

vehicle owner’s manual (which includes 

information provided by the vehicle 

manufacturer to the consumer, whether 


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392 Federal Register / Vol. 90, No. 2 / Friday, January 3, 2025 / Rules and Regulations 

1Children in booster seats are part of the target 

population for this final rule because they should 

be restrained with the seat belt and so would 

benefit from a seat belt reminder. The transition to 

a booster seat typically occurs from ages 4–7 years, 

and recommendations to remain in a booster seat 

exist until age 12 years.https://www.nhtsa.gov/ 

vehicle-safety/car-seats-and-booster-seats#find-theright-car-seat-car-seat-recommendations. 

2The Abbreviated Injury Scale (AIS) is a 

classification system for assessing impact injury 

severity developed and published by the 

Association for the Advancement of Automotive 

Medicine and is used for coding single injuries, 

assessing multiple injuries, or for assessing 

cumulative effects of more than one injury. MAIS 

represents the maximum injury severity of an 

occupant at an AIS level, i.e., the highest single AIS 

for a person with one or more injuries. MAIS 1 & 

2 injuries are considered minor injuries and MAIS 

3–5 are considered serious injuries. 

in digital or printed form) must describe 

the warning system’s features, including 

the location and format of the visual 

warnings. It must also include 

instructions on how to make any 

manual electrical connections for 

readily removable seats. 

2. Front Outboard Seat Belt Warning 

Requirements 

The final rule includes several 

changes and enhancements to the seat 

belt warning requirements for the front 

outboard seats. The new requirements 

have two main elements. 

• Seat belt warning now required for 

front outboard passenger seat. This final 

rule requires a seat belt warning for the 

front outboard passenger seat. It does 

not require one for front center seats 

because, among other things, doing so 

would not be cost-effective. Currently, 

only the driver’s seat is required to have 

a seat belt warning, although almost all 

vehicles now provide a seat belt 

warning for the front outboard 

passenger seat as well. 

• Enhanced audio-visual seat belt 

warning. The final rule requires a 

longer-duration audio-visual warning 

than is currently required for the 

driver’s seat belt. The final requirements 

for this warning differ from the 

proposal, which would have required 

(with some exceptions) an audio-visual 

warning lasting until the belt at any 

occupied front outboard seat was 

fastened. This included a warning at the 

start of a trip and if a belt was 

unfastened during a trip. The proposal 

did not include any other warning 

triggers, such as vehicle speed. The final 

rule requires a visual warning and a 

two-phase audible warning that is 

based, in part, on vehicle speed. 

Visual warning. Under the final rule, 

a visual warning is required whenever 

the ignition switch is in the ‘‘on’’ or 

‘‘start’’ position (or the propulsion 

system is activated), the seat is 

occupied, and the seat belt is not in use. 

The warning must be visible to the 

driver. 

Audible warning. The final rule 

requires a two-phase audible warning. 

The first phase warning must activate 

when the ignition/propulsion system is 

activated, the seat is occupied, and the 

belt is not in use. The first phase 

warning must last for at least 30 

seconds, unless the seat belt that 

triggered the warning is fastened or the 

second phase audible warning is 

activated within that time. The second 

phase audible warning must activate, 

and remain active, whenever the seat is 

occupied, the seat belt is not in use, and 

the vehicle speed is at least 10 km/h (6.2 

mph). The audible warning may be 

temporarily paused to allow another 

audible safety warning alerting the 

driver to take immediate action. 

The final rule also contains 

requirements for the visual and audible 

warnings as well as for other system 

features. 

Compliance Date 

This final rule establishes a 

compliance date for the amendments to 

FMVSS No. 208, ‘‘Occupant crash 

protection,’’ as follows. Manufacturers 

must comply with the amendments as of 

September 1, 2026 for the front seat belt 

warning system requirements and 

September 1, 2027 for the rear seat belt 

warning system requirements, with 

optional early compliance (see Section 

IX for details). Consistent with 49 CFR 

571.8(b), multi-stage manufacturers and 

alterers have an additional year to 

comply. 

Regulatory Alternatives 

NHTSA considered a wide range of 

alternatives to the proposed 

requirements. The main alternatives 

NHTSA considered were the seat belt 

warning requirements in Economic 

Commission for Europe (ECE) 

Regulation No. 16 (R16) and Euro New 

Car Assessment Programme (Euro 

NCAP). The finalized requirements are 

identical or similar to ECE R16 and Euro 

NCAP in many respects but differ from 

them in several ways. For instance, 

while under ECE R16 the smallest 

occupant a rear seat belt system with 

occupant detection must be capable of 

detecting is a small-statured adult 

female, under the final rule such 

systems must be capable of detecting 

occupants as small as a 6-year-old child 

and activating the warning accordingly. 

Another way the proposal differs from 

ECE R16 is the duration of the front seat 

belt warning on vehicle start-up: R16 

generally requires only a 30–60 second 

audio-visual warning; the final rule 

requires, under certain conditions, an 

audio-visual warning that lasts until the 

seat belt is buckled. The final regulatory 

analysis quantifies the costs and 

benefits of three specific regulatory 

alternatives: requiring occupant 

detection for the rear seat belt warning 

system; requiring (for the front outboard 

seats) an audio-visual warning on 

vehicle start-up with a duration of 90 

seconds; and requiring a seat belt 

warning for front center seats. 

Benefits and Costs of the Proposed 

Requirements 

This final rule is significant and was 

reviewed by the Office of Management 

and Budget under Executive Order 

12866, as amended by Executive Order 

14094. 

NHTSA estimates the target 

population and the benefits and costs of 

the final rule requirements in the standalone final regulatory impact analysis 

(FRIA) that is being placed in the docket 

with this final rule and is summarized 

in this document. 

Based on NHTSA’s data on fatalities 

and injuries from motor vehicle crashes, 

adjusted to account for the benefits of 

other mandatory safety technologies, 

there are, on average, 822 fatalities and 

11,409 injuries to unrestrained rear seat 

occupants and 8,383 fatalities and 

154,739 injuries to unrestrained front 

outboard seat occupants each year. The 

final rule requirements are aimed at 

reducing these deaths and injuries. 

NHTSA estimates the benefits it 

expects from the final rule seat belt 

warning requirements. The benefits are 

the fatalities and injuries that would be 

prevented by these requirements. The 

benefits depend, principally, on the 

expected increase in seat belt use and 

the effectiveness of seat belts in 

preventing deaths and injuries. 

For the rear seat belt warning system 

analysis, NHTSA used a ‘‘low’’ and a 

‘‘high’’ estimate for the increase in rear 

belt use with the warning system. For 

occupants 11 years and older, these 

were 3 and 5 percentage points, 

respectively, and for occupants from 6 

to 10 years old, 0.3 and 0.4 percentage 

points respectively.1 For simplicity, 

NHTSA refers to these scenarios as 

‘‘Low’’ and ‘‘High.’’ The estimated 

annual benefits for rear seat belt 

warning systems are presented in table 

1.2


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TABLE 1—ESTIMATED ANNUAL BENEFITS—POTENTIAL LIVES SAVED AND INJURIES PREVENTED FOR REAR SEAT BELT

WARNING SYSTEMS (SBWS) WITHOUT OCCUPANT DETECTION, WITH ESTIMATED ‘‘LOW’’ AND ‘‘HIGH’’ PERCENTAGE

POINT INCREASE IN BELT USE

Injury level Low High 

MAIS 1 ..................................................................................................................................................................... 36 54 

MAIS 2 ..................................................................................................................................................................... 80 120 

MAIS 3 ..................................................................................................................................................................... 26 38 

MAIS 4 ..................................................................................................................................................................... 4 6 

MAIS 5 ..................................................................................................................................................................... 1 2 

Total Injuries ..................................................................................................................................................... 148 221 

Fatal ......................................................................................................................................................................... 26 39 

Another way to measure benefits is by 

calculating equivalent lives saved (ELS). 

Equivalent lives saved are the number of 

prevented fatalities added to the number 

of prevented injuries, with the 

prevented injuries expressed in terms of 

fatalities (that is, with an injury 

expressed as a fraction of a fatality, so 

that the more serious the injury, the 

higher the fraction). The estimated 

equivalent lives saved assuming either a 

3 percent or 7 percent discount rate are 

presented in table 2. 

TABLE 2—ESTIMATED ANNUAL BENEFITS—EQUIVALENT LIVES SAVED (ELS)—REAR SBWS WITHOUT OCCUPANT

DETECTION

Belt use increase 3 Percent 

discount rate 

7 Percent 

discount rate 

Low ...................................................................................................................................................................... 29.98 24.31 

High ...................................................................................................................................................................... 45.09 36.55 

NHTSA also estimates the costs of the 

final rule requirements for rear seat belt 

warnings. NHTSA estimates that the 

minimum cost to comply with the rear 

seat belt warning requirements is 

$166.44 million (M). This is based on a 

per-vehicle cost of $19.59 for 53.1 

percent of 16M affected new vehicles. 

Based on the foregoing, NHTSA 

performed benefit-cost and costeffectiveness analyses. A benefit-cost 

analysis calculates the net benefits, 

which is the difference between the 

benefits flowing from injury and fatality 

reductions and the cost of the rule. The 

net benefit estimates are presented in 

table 3. The cost-effectiveness analysis 

derives the cost per equivalent life 

saved, which is equal to the total cost 

of the rule divided by the total fatal 

equivalents that it prevents. These 

estimates are presented in table 4. 

TABLE 3—NET BENEFITS—REAR SBWS WITHOUT OCCUPANT DETECTION

[2020 Dollars, in millions] 

Belt use increase 

Benefits 

3 percent 

discount 

Benefits 

7 percent 

discount 

Cost 

Net benefits 

3 percent 

discount rate 

Net benefits 

7 percent 

discount rate 

Low ........................................................................................... $357.78 $290.05 $166.4 $191.34 $123.62 

High .......................................................................................... 538.00 436.16 166.4 371.56 269.72

TABLE 4—COST-EFFECTIVENESS ANALYSIS (COST PER EQUIVALENT LIFE SAVED)—REAR SBWS WITHOUT OCCUPANT

DETECTION

[2020 Dollars, in Millions] 

Belt use increase 

ELS 3 

percent 

discount 

ELS 7 

percent 

discount 

Cost 

Cost/ELS 

3 percent 

discount 

Cost/ELS 

7 percent 

discount 

Low ................................................................................................... 29.98 24.31 $166.4 $5.55 $6.85 

High .................................................................................................. 45.09 36.55 166.4 3.69 4.55 

This final rule also enhances the 

driver seat belt warning requirements by 

requiring an indefinite visual warning 

and a two-phase audible warning that is 

based, in part, on vehicle speed that 

remains active until the driver’s seat 

belt is buckled and extending these 

enhanced driver’s seat belt warning 

requirements to the front outboard 

passenger seat. NHTSA estimates the 

annual benefits of a seat belt warning for 

the driver and outboard front passenger 

that remains active until the occupant’s 

seat belt is buckled as shown in table 5 

and table 6. 


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I I I I 

I I I I 
394 Federal Register / Vol. 90, No. 2 / Friday, January 3, 2025 / Rules and Regulations 

3Based on data on total projected vehicle sales in 

the United States for MY 2022 from the agency’s 

New Car Assessment Program Purchasing with Safety in Mind: What to Look For When Buying a 

Vehicle program. 

TABLE 5—ESTIMATED ANNUAL BENEFITS—LIVES SAVED AND INJURIES PREVENTED—INDEFINITE DURATION SBWS 

(FRONT OUTBOARD SEATS) 

Injury level Driver Front 

passenger Total 

MAIS 1 ......................................................................................................................................... 129 14 143 

MAIS 2 ......................................................................................................................................... 151 19 170 

MAIS 3 ......................................................................................................................................... 62 8 69 

MAIS 4 ......................................................................................................................................... 9 1 10 

MAIS 5 ......................................................................................................................................... 3 0 3 

Total Injuries ......................................................................................................................... 354 42 395 

Fatal ............................................................................................................................................. 20 2 22 

TABLE 6—ESTIMATED ANNUAL BENEFITS—EQUIVALENT LIVES SAVED—INDEFINITE DURATION SBWS (FRONT OUTBOARD

SEATS) 

Undiscounted 3 Percent 

discount rate 

7 Percent 

discount rate 

Driver ....................................................................................................................................... 42.26 34.98 28.36 

Front Passenger ...................................................................................................................... 4.44 3.68 2.99 

Total .................................................................................................................................. 46.70 38.66 31.35 

NHTSA estimates that the 

incremental cost of the enhanced seat 

belt warning for the driver’s seat and the 

front outboard passenger seat would be 

no greater than the currently available 

seat belt warning. Although a seat belt 

warning is currently not required for the 

front outboard passenger seats, we 

estimate that 96 percent of new vehicles 

are equipped with them.3 NHTSA 

estimates that the cost for equipping a 

front outboard passenger seat with a seat 

belt warning system is about $2.13 per 

vehicle. To equip a seat belt warning 

system in the front outboard passenger 

seat positions on the remaining four 

percent of the new vehicle fleet (16 

million) without such a warning is 

$1.36 million (= $2.13 × 0.04 × 16 

million). 

The total monetized benefits, costs, 

and net benefits (total monetized 

benefits—total cost) of the enhanced 

seat belt warning system for the driver 

and front passenger are shown in table 

7. Table 8 presents the results of the cost 

effectiveness analysis—cost per 

equivalent lives saved from enhanced 

SBWS for the driver and front outboard 

passenger. 

TABLE 7—ANNUAL MONETIZED BENEFITS, COSTS, AND NET BENEFITS—INDEFINITE SBWS (FRONT OUTBOARD SEATS) 

[2020 Dollars, in Millions] 

Driver Front passenger Driver and front 

passenger 

3 Percent 7 Percent 3 Percent 7 Percent 3 Percent 7 Percent 

Passenger Car Benefits ................................................... $188.89 $154.12 $22.86 $18.65 $211.75 $172.77 

Light Truck & Van Benefits .............................................. 228.51 184.29 21.05 16.97 249.56 201.26 

Total Benefits ............................................................ 417.41 338.41 43.90 35.62 461.31 374.03 

Total Costs ................................................................ 0 0 1.36 1.36 1.36 1.36 

Net Benefits ..................................................................... 417.41 338.41 42.54 34.26 459.95 372.67 

TABLE 8—COST-EFFECTIVENESS ANALYSIS (COST PER EQUIVALENT LIFE SAVED)—INDEFINITE SBWS (FRONT OUTBOARD

SEATS) 

[2020 Dollars, in millions] 

Discount rate ELS Cost Cost/ELS 

3 percent ...................................................................................................................................... 38.66 $1.36 $0.04 

7 percent ...................................................................................................................................... 31.35 1.36 0.04 

The net benefits of the final rule 

requiring seat belt warning for rear 

seating positions and the enhanced seat 

belt warning for the front outboard seats 

are shown in table 9. The net benefits 

are positive for both 3 percent and 7 


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Federal Register / Vol. 90, No. 2 / Friday, January 3, 2025 / Rules and Regulations 395 

4 88 FR 61674. 

5 Id. at pgs. 61680–61686. 

6See, e.g., 68 FR 46262 (Aug. 5, 2003). See also 

Buckling Up: Technologies to Increase Seat Belt 

Use. Special Report 278 at 18, Committee for the 

Safety Belt Technology Study, Transportation 

Research Board of The National Academies (2003). 

7Charles J. Kahane, Lives Saved by Vehicle Safety 

Technologies and Associated Federal Motor Vehicle 

Safety Standards, 1960 to 2012—Passenger Cars and 

LTVs—With Reviews of 26 FMVSS and the 

Effectiveness of Their Associated Safety 

Technologies in Reducing Fatalities, Injuries, and 

Crashes. 89 DOT HS 812 069 at 89, Department of 

Transportation, National Highway Traffic Safety 

Administration (2015). 

8See the Final Regulatory Impact Analysis (FRIA) 

(in the docket for this rulemaking) for these 

effectiveness estimates. 

9Boyle, L.L. (2022, August). Occupant restraint 

use in 2021: Results from the NOPUS Controlled 

Intersection Study (Report No. DOT HS 813 344). 

National Highway Traffic Safety Administration. 

NOPUS is the only nationwide probability-based 

observational survey of seat belt use in the United 

States. The survey observes seat belt use as it 

actually occurs at randomly-selected roadway sites, 

and involves a large number of occupants (68,804 

in 2021). NOPUS observations are made during 

daylight hours and are not necessarily 

representative of high-risk driving times when belt 

use may be lower. 

10Boyle, L.L. (2023, November). Occupant 

restraint use in 2022: Results from the NOPUS 

Controlled Intersection Study (Report No. DOT HS 

813 523). National Highway Traffic Safety 

Administration. 

percent discount rates and for both the low and high effectiveness estimates for 

rear seat SBWS. 

TABLE 9—NET BENEFITS FROM THE FINAL RULE (SBWS WITHOUT OCCUPANT DETECTION FOR REAR SEATING

POSITIONS AND INDEFINITE SBWS FOR FRONT OUTBOARD SEATING POSITIONS) 

[2020 Dollars, in millions] 

3 Percent 

discount rate 

7 Percent 

discount rate 

Front Outboard Seats .............................................................................................................................................. $459.95 $372.67 

Rear Seats (low increase in rear seat belt use) ..................................................................................................... 191.34 123.62 

Rear Seats (high increase in rear seat belt use) .................................................................................................... 371.56 269.72 

Total Net Benefits (low increase in rear belt use) ........................................................................................... 651.29 496.28 

Total Net Benefits (high increase in rear belt use) .......................................................................................... 831.51 642.39 

II. Background 

On September 7, 2023, NHTSA 

published a notice of proposed 

rulemaking (NPRM) to amend FMVSS 

No. 208, ‘‘Occupant crash protection,’’ 

to require a seat belt use warning system 

for rear seats and to enhance the 

existing front seat belt warning 

requirements, including requiring a seat 

belt warning for the front outboard 

passenger seat and increasing the 

duration of the warning.4 This section 

provides an abbreviated background on 

the subject matter and regulatory history 

of the proposed requirements. For a 

fuller discussion, the reader is referred 

to the NPRM.5

Seat Belts and Seat Belt Warning 

Systems 

Using a seat belt is one of the most 

effective actions a motor vehicle 

occupant can take to prevent death and 

injury in a crash.6 Seat belts protect 

occupants in various ways. They 

prevent occupants from being ejected 

from the vehicle, gradually decelerate 

the occupant as the vehicle deforms and 

absorbs energy, and reduce the 

occurrence of occupant contact with 

harmful interior surfaces and other 

occupants.7 Research has found that 

seat belts greatly reduce the risk of fatal 

and non-fatal injuries compared to the 

risk faced by unrestrained occupants. 

For rear seat occupants, seat belts 

reduce the risk of fatality by 55 percent 

(for passenger cars) and 74 percent (for 

light trucks and vans). For drivers, seat 

belts reduce the risk of fatality by 48 

percent (for passenger cars) and 61 

percent (for light trucks and vans) and 

reduce the risk of moderate to greater 

severity injuries by 65 percent. For front 

outboard passengers, seat belts reduce 

the risk of fatality by 37 percent (for 

passenger cars) and by 58 percent (for 

light trucks and vans) and reduce the 

risk of moderate to greater severity 

injuries by 65 percent.8

While seat belt use is meaningfully 

higher than it was a decade ago, there 

is room for improvement. Usage rates 

for rear seat belts have consistently been 

below those for the front seats, and 

while front seat belt use rates increased 

early in the previous decade, for the last 

several years they have plateaued. 

According to data from NHTSA’s 

National Occupant Protection Use 

Survey (NOPUS), from 2013 to 2022, 

seat belt use was lower in the rear seat 

than in the front seat, ranging from a 

difference of 8.8 percentage points in 

2013 (78.3 percent vs. 87.1 percent) to 

14.3 percentage points in 2017 (75.4 

percent vs. 89.7 percent).9 In 2022, front 

seat belt use was 91.6 percent and rear 

seat belt use was 81.7 percent.10 See 

Figure 1. 


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396 Federal Register / Vol. 90, No. 2 / Friday, January 3, 2025 / Rules and Regulations 

11For example, NHTSA runs a Congressionally 

mandated High Visibility Enforcement annual 

campaign focused on increasing seat belt use. The 

Click It or Ticket nationwide campaign has been in 

effect for about 20 years. It runs every year from 

mid-May through the Memorial Day weekend, into 

the first week in June. 

12See also Section V of the NPRM (pgs. 61684– 

61685). 

13S4.1.5.1(a)(3); S7.3. 14S4.2.6; S7.3. 15S4.2.6 (with the exception of some compliance 

options). 16See, e.g., Interpretation Letter from NHTSA to 

R. Lucki, July 24, 1985 (‘‘Thus, the intent was to 

require a warning system for only the driver’s 

position.’’). All NHTSA interpretation letters cited 

in this preamble are available at https://

www.nhtsa.gov/nhtsa-interpretation-file-search. 17 49 CFR 571.208, S7.3. 18The warning requirements for automatic belts 

in S4.5.3 mirror, with some differences, the first 

compliance option. Automatic belts are rarely, if 

ever, installed in current production vehicles, and 

NHTSA’s regulations limit the seating positions for 

which automatic belts may be used to rear seats. 19 39 FR 42692 (Dec. 6, 1974). 

20Through the NCAP program, NHTSA sends 

annual requests for safety information about new 

vehicles to vehicle manufacturers. This includes 

specific questions on seat belt reminder systems. 

The focus of this request for information is for 

vehicle models that will be sold in the upcoming 

model year that have a GVWR of 4,536 kg (10,000 

lb) or less, and this data generally covers all such 

vehicles offered for sale in the U.S. for MY 2022. 

Throughout this document we will refer to this data 

as our ‘‘NCAP data’’ or ‘‘Purchasing with Safety in 

Mind: What to Look For When Buying a Vehicle’’ 

data or information. 

21See NPRM, pgs. 61709–61711, and appendix A. 

NHTSA has, over time, implemented 

a variety of strategies to increase seat 

belt use. These have included 

sponsoring national media campaigns, 

supporting the enactment of state seat 

belt use laws and high-visibility 

enforcement, and facilitating or 

requiring vehicle-based strategies.11

While such measures have helped make 

enormous progress, the persistent gaps 

in seat belt use suggest that additional 

approaches may be necessary. 

Seat belt warning systems (also 

referred to as seat belt reminder 

systems) are a vehicle-based strategy to 

increase belt use. Seat belt warning 

systems encourage seat belt use by 

reminding unbuckled occupants to 

fasten their belts and/or by informing 

the driver that a passenger is unbelted, 

so that the driver can request the 

unbelted occupant buckle up. The 

warnings provided by seat belt warning 

systems typically consist of visual and 

audible signals. An optimized warning 

system balances effectiveness and 

annoyance, so that the warning is 

noticeable enough that the occupants 

will be motivated to fasten their belts, 

but not so intrusive that an occupant 

may attempt to circumvent or disable it 

or the public will not accept it. Research 

by NHTSA and others shows that seat 

belt warning systems are effective at 

getting unbuckled occupants to fasten 

their seat belts. (We take a closer look 

at this research in Section VIII, 

Overview of Benefits and Costs, and the 

FRIA.) 12

FMVSS No. 208 currently requires a 

short audio-visual seat belt warning for 

the driver’s seat belt on passenger 

cars; 13 trucks and MPVs with a GVWR 

of 4,536 kg (10,000 lb) or less (except for 

some compliance options which do not 

require the warning); 14 and buses with 

a GVWR of 3,855 kg (8,500 lb) or less 

and an unloaded weight less than or 

equal to 2,495 kg (5,500 lb).15 The 

standard does not require seat belt 

warnings for any seating position other 

than the driver’s seat.16

Manufacturers have two compliance 

options for the driver’s warning.17 The 

first option requires that if the key is in 

the ‘‘on’’ or ‘‘start’’ position and the seat 

belt is not in use, the vehicle must 

provide a visual warning for at least 60 

seconds, and an audible warning that 

lasts 4 to 8 seconds. Under the second 

option, when the key is turned to the 

‘‘on’’ or ‘‘start’’ position, the vehicle 

must provide a visual warning for 4 to 

8 seconds (regardless of whether the 

driver seat belt is fastened) and an 

audible warning lasting 4 to 8 seconds 

if the driver seat belt is not in use.18 The 

current seat belt warning requirements 

(i.e., for the driver’s seat only) have been 

in the standard since 1974.19

Although not required by NHTSA’s 

regulations, most currently produced 

vehicles have a seat belt warning for the 

front outboard passenger seat. Based on 

data on total projected vehicle sales in 

the United States for MY 2022 from the 

agency’s New Car Assessment Program 

(NCAP) Purchasing with Safety in Mind: 

What to Look For When Buying a 

Vehicle program, almost all (about 97 

percent) MY 2022 vehicles offered for 

sale in the United States were equipped 

with a seat belt warning for the front 

outboard passenger seat.20 Further, 

almost all vehicles already provide an 

audio-visual seat belt warning for both 

front outboard seats that is longer than 

the minimum warning for the driver’s 

seat belt currently required in FMVSS 

No. 208. However, the persistence of the 

front seat belt warning, while often 

greater than the minimal durations 

required by FMVSS No. 208, is not 

consistent across new vehicles. 

Specifically, a little over half of MY 

2022 vehicles provide a visual warning 

that lasts until the belts at any occupied 

front outboard seat are fastened, and 

almost all (about 93 percent) have an 

audible warning lasting at least a minute 

and a half; however, less than half have 

an audible warning lasting at least two 

minutes.21 This means that while many 

new vehicles have significantly 

enhanced reminders, many do not. This 

disparity, along with the plateauing 

front seat belt use numbers, suggests 

that the current regulatory minima are 


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Figure 1 - Seat Belt Use by Seating Position for Occupants 8 and Older, 2013-2022 
Federal Register / Vol. 90, No. 2 / Friday, January 3, 2025 / Rules and Regulations 397 

22Mark Freedman et al. The Effectiveness of 

Enhanced Seat Belt Reminder Systems Draft Report: 

Observational Field Data Collection Methodology 

and Findings. 2007. DOT HS–810–844. Washington, 

DC: National Highway Traffic Safety 

Administration. 

23N. Lerner et al. 2007. Acceptability and 

Potential Effectiveness of Enhanced Seat Belt 

Reminder System Features. DOT HS 810 848. 

Washington, DC: National Highway Traffic Safety 

Administration [hereinafter DOT 2007. 

24Transportation Research Board Study at 8, 25; 

Mark Freedman et al., Effectiveness and Acceptance 

of Enhanced Seat Belt Reminder Systems: 

Characteristics of Optimal Reminder Systems Final 

Report. DOT HS 811 097. 

25 Docket No. NHTSA–2010–0061–0002. 

26 75 FR 37343 (June 29, 2010) (Docket No. 

NHTSA–2010–0061). 

27Public Law 112–141 (2012). 

28 Id. at section 31202(a)(2) (repealing portion of 

49 U.S.C. 30124). 

29 Id. at section 31503. Authority has been 

delegated to NHTSA. 49 CFR 1.95. 

30Section 30111 requires that a Motor Vehicle 

Safety Standard meet the need for safety, be stated 

in objective terms, and be practicable, among other 

requirements. See infra Section IV. 

31 84 FR 51076 (Sept. 27, 2019) (Docket No. 

NHTSA–2019–0093). 

32 88 FR 61674. 

33ECE Regulation No. 16, Revision 10. 

34The regulation was introduced in two phases: 

September 1, 2019 for new vehicle types (i.e., all 

vehicle models with a new type approval) and 

September 1, 2021 for all newly-produced and 

registered vehicles. 

35Euro NCAP’s overall safety rating is based on 

four areas of assessment (Adult Occupant 

Protection, Child Occupant Protection, Vulnerable 

Road Users, and Safety Assist). 

36European New Car Assessment Programme 

Assessment Protocol—Safety Assist, Safe Driving, 

Version 10.3, December 2023. 

too short, and that in the absence of a 

requirement, persistent audible 

reminders that could improve front seat 

belt use are not widely available in the 

market.22 23 24

While almost all MY 2022 vehicles 

have a seat belt warning for the front 

outboard passenger seat, under half 

come equipped with a rear seat belt 

warning system. Rear seat belt warnings 

were first introduced in the United 

States by Volvo around 2009. About 47 

percent of MY 2022 vehicles, from 15 

vehicle manufacturers, are equipped 

with a rear seat belt warning system. 

Thus, while rear seat belt warnings have 

become more widely deployed in recent 

years, the majority of the current fleet 

still is not equipped with them. 

In short, front seat belt use rates 

appear to have plateaued, and rear seat 

belt use rates have persistently been 

below those for the front seats. 

Moreover, unbuckled occupants 

continue to be overrepresented in fatal 

crashes (51 percent), given the lower 

exposure of unbelted occupants relative 

to belted occupants (because front seat 

belt use was about 90 percent and rear 

seat belt use was 80 percent for the 

period in question). In spite of the 

effectiveness of seat belts and seat belt 

warnings, most new vehicles continue 

to lack a rear seat belt warning, and, 

while many vehicles provide 

significantly enhanced reminders for the 

front seats, many do not. This suggests 

a need for a beneficial safety technology 

that is not being met in the vehicle 

market. This final rule is intended to 

meet that need. 

Rulemaking Petition, MAP–21 Mandate, 

and Prior Rulemaking Notices for This 

Action 

On November 21, 2007, Public Citizen 

and Advocates for Highway and Auto 

Safety (Advocates, and, collectively, 

petitioners) petitioned NHTSA to 

amend FMVSS No. 208 to require a seat 

belt warning system for rear seats on 

passenger cars and MPVs with a GVWR 

of 4,536 kg (10,000 lb) or less.25 On June 

29, 2010, the agency published a 

Request for Comments document (RFC) 

on the petition.26 The RFC discussed the 

agency’s research and findings regarding 

rear seat belt warnings and solicited 

comments. NHTSA subsequently 

granted the petition. 

In 2012, Congress passed the Moving 

Ahead for Progress in the 21st Century 

Act (MAP–21).27 That legislation 

contained two provisions regarding seat 

belt warning systems. First, it repealed 

the 8-second durational limit for the 

driver’s seat belt audible warning.28

Second, it required the Secretary of 

Transportation to initiate a rulemaking 

proceeding to amend FMVSS No. 208 to 

provide a safety belt use warning system 

for designated seating positions in the 

rear seat.29 It directed the Secretary to 

either issue a final rule, or, if the 

Secretary determines that such an 

amendment does not meet the 

requirements and considerations of 49 

U.S.C. 30111,30 to submit a report to 

Congress describing the reasons for not 

prescribing such a standard. 

In 2019, NHTSA published an 

Advance Notice of Proposed 

Rulemaking (ANPRM) seeking comment 

on a variety of issues related to potential 

rear seat belt warning requirements.31

NHTSA published the NPRM on 

September 7, 2023.32

III. Other Seat Belt Reminder 

Requirements and Protocols 

The Economic Commission for 

Europe (ECE) has instituted seat belt 

warning requirements, and the 

European New Car Assessment 

Programme (Euro NCAP) and the 

Insurance Institute for Highway Safety 

(IIHS) have also included seat belt 

reminder systems in their respective 

ratings protocols. Below we briefly 

summarize the seat belt reminder 

provisions in each of these. 

ECE Requirements 

The ECE has issued an updated 

version of Regulation No. 16 33 (R16) 

that requires seat belt reminder systems 

in all front and rear seats on new cars.34

The seat belt reminder system is 

required to have both a start-of-trip 

warning and a change-of-status warning 

for both the rear and front seats, though 

the exact requirements differ somewhat 

for rear and front seats. 

Rear seat requirements. R16 specifies 

a two-level warning. The first-level 

warning is a visual warning and the 

second-level warning is an audio-visual 

warning. The first-level warning applies 

at the start of a trip and the second-level 

warning applies when a fastened belt 

becomes unfastened during a trip. The 

first-level warning must activate when 

the seat belt of any of the rear seats is 

not fastened and the ignition switch or 

master control switch is activated. The 

first-level warning must last at least 60 

seconds or until the belt is fastened (or 

the seat is no longer occupied, if 

equipped with occupant detection). The 

second-level warning must activate 

when a belt becomes unfastened and 

certain specified speed or distance 

thresholds are met and must last for 30 

seconds unless other specified criteria 

are met (e.g., the belt is re-fastened). 

Front seat requirements. The front 

seat belt warning requirements are 

similar to the rear seat warnings, with 

some differences. First, the first-level 

visual warning is only required to last 

30 seconds, not 60 seconds. Second, the 

second-level audio-visual warning 

applies to unfastened belts at the start 

of the trip as well as to changes in belt 

status (i.e., a fastened belt that becomes 

unfastened). 

The regulation also contains a variety 

of other requirements relating to the seat 

belt warning systems (e.g., telltales, 

exemptions for certain vehicles and 

seating positions). R16 also allows for 

short- and long-term deactivation of 

both front and rear warnings. 

The ECE requirements are discussed 

in more detail where relevant in later 

sections of this preamble. 

Euro NCAP 

Euro NCAP introduced seat belt 

warnings in their assessment protocol in 

2002. The Euro NCAP protocol for 

Safety Assist systems describes which 

features a seat belt reminder must have 

to qualify for points in this area of 

assessment,35 which is then used to 

calculate the overall vehicle rating.36


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37This language remains in the protocol as a 

precondition for receiving a score for seats with 

occupant detection. In a vehicle where not all the 

rear seats are equipped with occupant detection, if 

seats without occupant detection do not meet these 

requirements the seats with occupant detection 

would not receive a score. 

38Section 3.4.2.1. 

39 Insurance Institute for Highway Safety. (April 

2024.) Seat Belt Reminder System Test and Rating 

Protocol, Version III, available at https://

www.iihs.org/media/f15e5be9-ac62-4ea6-a88d7511105bfff5/H3hGKQ/Ratings/Protocols/current/ 

Seat%20Belt%20Reminder%20

Test%20Protocol.pdf (last accessed May 16, 2024). 

40See 49 CFR 1.95. 

41 49 U.S.C. 30111(a). 

42 49 U.S.C. 30102(a)(9). 

43Section 30102(a)(10). 

44Section 30111(b)(1). 

45Section 30111(b)(3)–(4). 

46See, e.g., Motor Vehicle Mfrs. Ass’n of U.S., Inc. 

v. State Farm Mut. Auto. Ins. Co., 463 U.S. 29, 55 

(1983) (‘‘The agency is correct to look at the costs 

as well as the benefits of Standard 208 . . . When 

the agency reexamines its findings as to the likely 

increase in seatbelt usage, it must also reconsider 

its judgment of the reasonableness of the monetary 

and other costs associated with the Standard. In 

reaching its judgment, NHTSA should bear in mind 

that Congress intended safety to be the preeminent 

factor under the Motor Vehicle Safety Act.’’). 

47See, e.g., Public Citizen, Inc. v. Mineta, 340 

F.3d 39, 58 (2nd Cir. 2003) (‘‘The notion that 

‘cheapest is best’ is contrary to State Farm. There 

the Court instructed NHTSA ‘to look at the costs as 

well as the benefits’ of motor vehicle safety 

standards, and to ‘‘bear in mind that Congress 

intended safety to be the pre-eminent factor under 

the [Safety Act.] Thus, when NHTSA issues 

Rear seat warnings. For rear seats, a 

visual signal must start once the ignition 

switch is engaged. The visual signal 

must be at least 60 seconds long. 

Occupant detection is required for rear 

seats to be eligible for a score; this is a 

new requirement that was instituted 

after NHTSA published the NPRM. For 

systems without occupant detection,37

the visual signal must clearly indicate to 

the driver which seat belts are in use 

and not in use. For systems with 

occupant detection on all rear seating 

positions, the visual signal does not 

need to indicate the number of seat belts 

in use or not in use, but the signal must 

remain active if a seat belt remains 

unfastened on any of the occupied seats 

in the rear. No visual signal is required 

if all the rear occupants are belted. For 

systems with rear seat occupant 

detection, a 30-second audible signal 

needs to activate before the vehicle 

reaches a speed of 25 km/h (15.5 mph) 

or before it travels 500 meters when any 

occupied seat has an unbuckled belt. 

When any seat belt experiences a 

change of status at vehicle speeds above 

25 km/h (15.5 mph), an audio-visual 

signal is required, with the visual signal 

lasting 60 seconds and the audible 

warning lasting 30 seconds, unless 

certain conditions are met. 

Front seat warnings. The Euro NCAP 

protocol requires that, to receive points, 

at the start of a trip the system must 

provide a visual seat belt warning that 

lasts until the belt is fastened 38 and an 

audible warning that activates when 

certain conditions are met and generally 

must last at least about 90 seconds (the 

exact duration depends on a variety of 

specified criteria, such as vehicle speed 

or distance travelled). It also specifies 

an audio-visual change-of-status 

warning that meets the requirements of 

the initial start-of-trip warning. 

Insurance Institute for Highway Safety 

(IIHS) Protocol 

On December 2021, IIHS released its 

Seat Belt Reminder System Test and 

Rating protocol.39 It sets out general 

requirements for the seat belt reminder 

visual and audible signals for front 

outboard and rear seating positions. It 

specifies that a visual signal must be 

displayed in the instrument panel, 

overhead panel, or center console, 

indicating an unfastened belt. The 

audible warning must begin if the seat 

belt is unfastened at ignition and for 

change-of-status, and can cease when 

the seat belt is unfastened, the vehicle 

is no longer in motion, or the seat is no 

longer occupied. The protocol also has 

sound pressure level and frequency 

requirements for the audible warning. 

For the rear seats, the IIHS protocol 

specifies that the visual signal must 

activate within 10 seconds of the 

ignition being turned on, that the signal 

must indicate whether the seat belt at 

each rear seating position is fastened or 

unfastened, and that it must last at least 

60 seconds. It does not require a visual 

signal if the seat belts at all occupied 

rear seats are fastened or if no rear 

occupants are present. It allows the 

visual signal to be cancelled by the 

driver. For a seat belt change-of-status in 

the rear seats when the vehicle is in 

motion, it requires an audible and visual 

signal that lasts at least 30 seconds. It 

further specifies that the audible and 

visual signal can stop when seat belts at 

the occupied rear seats are fastened, the 

vehicle is no longer in motion, or the 

seats are no longer occupied. 

For the front seats, under the IIHS 

ratings protocol, the primary audible 

reminder signal for the front outboard 

seats must be at least 90 seconds in total 

duration to obtain an ‘‘acceptable’’ or 

‘‘good’’ rating. 

Unlike Euro NCAP, the IIHS rating 

system provides ratings (Poor, Marginal, 

Acceptable, and Good) instead of points. 

For instance, if the front-passenger seat 

has an audible signal that lasts less than 

8 seconds it would be given a ‘‘Poor’’ 

rating. For a ‘‘Good’’ rating both the 

driver and front-passenger belt reminder 

must have an audible signal that lasts at 

least 90 seconds and meet the rest of the 

belt reminder system requirements for 

an ‘‘Acceptable’’ rating, including the 

requirements for a rear seat belt 

reminder system. Accordingly, a vehicle 

cannot receive a ‘‘Good’’ rating without 

having a rear seat belt reminder system, 

and a rear seat belt reminder system is 

not required for all the other ratings. 

The protocol does not specify 

occupancy criteria (that is, the smallest 

occupant (or the size and weight 

corresponding to the smallest 

occupant)) that the system must be able 

to detect. 

IV. Statutory Authority 

NHTSA is issuing this final rule 

pursuant to its authority under the 

National Traffic and Motor Vehicle 

Safety Act (Safety Act). Under 49 U.S.C. 

chapter 301, Motor Vehicle Safety (49 

U.S.C. 30101 et seq.), the Secretary of 

Transportation is responsible for 

prescribing motor vehicle safety 

standards. The responsibility for 

promulgation of FMVSS is delegated to 

NHTSA.40

Section 30111 of the Safety Act 

requires that an FMVSS be practicable, 

meet the need for motor vehicle safety, 

and be stated in objective terms.41 The 

Safety Act defines ‘‘motor vehicle 

safety’’ as ‘‘the performance of a motor 

vehicle or motor vehicle equipment in 

a way that protects the public against 

unreasonable risk of accidents occurring 

because of the design, construction, or 

performance of a motor vehicle, and 

against unreasonable risk of death or 

injury in an accident, and includes 

nonoperational safety of a motor 

vehicle.’’ 42 ‘‘Motor vehicle safety 

standard’’ means a minimum 

performance standard for motor vehicles 

or motor vehicle equipment.43 When 

prescribing safety standards, the 

Secretary must consider all relevant, 

available motor vehicle safety 

information.44 The Secretary must also 

consider whether a proposed standard is 

reasonable, practicable, and appropriate 

for the types of motor vehicles or motor 

vehicle equipment for which it is 

prescribed, and the extent to which the 

standard will further the statutory 

purpose of reducing traffic accidents 

and associated deaths.45

The statutory criterion of 

practicability is multidimensional. Most 

relevant to this rule, it means that in 

issuing this final rule, NHTSA must 

balance benefits and costs, with safety 

as the preeminent consideration.46 This 

requirement means that NHTSA ought 

not simply choose the least costly 

regulatory option.47 It also means that 


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Federal Register / Vol. 90, No. 2 / Friday, January 3, 2025 / Rules and Regulations 399 

standards under the Safety Act, State Farm requires 

that the agency weigh safety benefits against 

economic costs; moreover, State Farm instructs the 

agency to place a thumb on the safety side of the 

scale.’’) (quoting Motor Vehicle Mfrs. Ass’n of U.S., 

Inc., 463 U.S. at 54) (citations omitted). 48See, e.g., Public Citizen, Inc. v. Mineta, 340 

F.3d at 58 (2nd Cir. 2003) (‘‘The committee 

recognizes . . . that the Secretary will necessarily 

consider reasonableness of cost, feasibility and 

adequate lead time.’’) (quoting H. Rep. No. 1776, at 

16 (1966)). 49See, e.g., Paccar, Inc. v. Nat’l Highway Traffic 

Safety Admin., 573 F.2d 632, 635 n.5 (9th Cir. 1978) 

(‘‘Practicable is defined to require consideration of 

all relevant factors, including technological ability 

to achieve the goal of a particular standard[.]’’) 

(citations and quotations omitted) (quoting H.R. 

Rep. No. 1776, 89th Cong., 2d Sess. 16 (1966)). 50Chrysler Corp. v. Dep’t of Transp., 472 F.2d 

659, 673 (6th Cir. 1972) (‘‘[T]he Agency is 

empowered to issue safety standards which require 

improvements in existing technology or which 

require the development of new technology, and it 

is not limited to issuing standards based solely on 

devices already fully developed.’’). 51Pac. Legal Found. v. Dep’t of Transp., 593 F.2d 

1338, 1345–46 (D.C. Cir. 1979) (‘‘We believe that the 

agency cannot fulfill its statutory responsibility 

unless it considers popular reaction. Without public 

cooperation there can be no assurance that a safety 

system can meet the need for motor vehicle 

safety.’’) (quotations and citations omitted). 

52 2 U.S. Code Cong. & Adm. News, 89th Cong., 

2d Sess., 1966, p. 2714, quoted in H & H Tire Co. 

v. U. S. Dep’t of Transp., 471 F.2d 350, 353 (7th 

Cir. 1972). (‘‘The committee recognizes . . . that the 

Secretary will necessarily consider [in the issuance 

of standards] reasonableness of cost, feasibility and 

adequate lead time.’’). 

53We note the preamble language imprecisely 

indicated the necessity for a belt latch sensor. As 

discussed later in this document, it was not our 

intention to require a specific technology. 

the final rule must be reasonably 

feasible, both economically 48 and 

technologically.49 Importantly, 

however, the Safety Act does allow 

NHTSA to issue technology-forcing 

safety standards.50 NHTSA must also 

consider the public acceptability of 

safety standards 51 and provide adequate 

lead time.52

In developing this final rule, the 

agency carefully considered these 

statutory requirements and has 

concluded that it meets them. They are 

discussed in more detail throughout the 

preamble and in the regulatory analyses 

where relevant. 

V. Summary of the NPRM 

The NPRM had two main 

components. The first proposed 

requiring a seat belt reminder for the 

rear seats. The second proposed changes 

and enhancements to the seat belt 

warning requirements for the front 

outboard seats, most notably an audiovisual warning that persists until the 

seat belt at any occupied front outboard 

seat is fastened. These proposed 

requirements would apply to passenger 

cars and trucks, buses (except school 

buses), and MPVs with a GVWR of 4,536 

kg (10,000 lb) or less. 

Rear Seat Belt Reminder Requirements 

The first component of the NPRM was 

a set of proposed requirements for a seat 

belt warning for rear seats. The 

proposed requirements had four main 

elements. 

• Visual warning on vehicle start-up 

to inform the driver of the status of the 

rear seat belts. We proposed three 

different compliance options from 

which manufacturers could choose for 

the rear seat belt warning system. The 

first would require the system to 

indicate how many or which rear seat 

belts are in use (the ‘‘positive-only’’ 

option). The second would require the 

system to indicate, for the occupied rear 

seats, how many or which rear seat belts 

are not in use (the ‘‘negative-only’’ 

option). The third would require the 

system to indicate, for the occupied rear 

seats, how many or which rear seat belts 

are in use and how many or which rear 

seat belts are not in use (the ‘‘fullstatus’’ option). Certain features would 

be required of all the options. Each 

system would have to provide a 

continuous or flashing visual warning, 

consisting of either icons or text, visible 

to the driver. The visual warning would 

have to last for at least 60 seconds, 

beginning when the vehicle’s ignition 

switch is moved to the ‘‘on’’ or ‘‘start’’ 

position. All the systems would require 

that the vehicle be equipped with 

technology to determine that the belt 

latch is fastened.53 The negative-only 

and full-status compliance options 

would additionally have required that 

the vehicle be equipped with an 

occupant detection system (which 

facilitates these more informative 

warnings). 

• Audio-visual change-of-status 

warning. We proposed an audio-visual 

warning whenever a fastened rear seat 

belt is unfastened while the ignition 

switch is in the ‘‘on’’ or ‘‘start’’ position 

and the vehicle’s transmission selector 

is in a forward or reverse gear. The 

warning would have to last for at least 

30 seconds. We did not propose any 

requirements for the volume or tone of 

the warning. The intent of this warning 

was to alert the driver or other 

occupants to a change in belt status 

during a trip. The warning would not be 

required if a door is open, which would 

be the case if a rear passenger 

unfastened their belt in order to exit the 

vehicle. 

• Requirements related to electrical 

connections. We proposed to require 

that readily removable rear seats either 

automatically re-establish the necessary 

electrical connections, or, if a manual 

connection is required, have readily 

accessible connectors. Further, vehicles 

with the negative-only compliance 

option would be required to provide a 

visual warning to the driver if a proper 

electrical connection has not been 

established for a readily removable rear 

seat. 

• Owner’s manual requirements. We 

proposed that the vehicle owner’s 

manual (which includes information 

provided by the vehicle manufacturer to 

the consumer, whether in digital or 

printed form) describe the warning 

system’s features (including the location 

and format of the visual warnings) and 

include instructions on how to make 

any manual electrical connections for 

readily removable seats. 

Front Outboard Seat Belt Warning 

Requirements 

The NPRM included several 

enhancements to the seat belt warning 

requirements for the front outboard 

seats. We proposed three main changes. 

• Audio-visual warning on vehicle 

start-up for front outboard passenger 

seat. We proposed to require a seat belt 

warning for the front outboard 

passenger seat. 

• Increasing the duration of the 

audio-visual warning on vehicle startup. We proposed enhancing the front 

seat warning requirements by requiring 

an audio-visual warning that remains 

active until the seat belt at any occupied 

front outboard seat is fastened. Vehicle 

manufacturers could adjust the 

characteristics of the auditory warning 

signal (such as frequency and volume) 

to make the warning both effective and 

acceptable to consumers. The proposal 

included specific duty cycle 

characteristics. 

• Audio-visual change-of-status 

warning. We also proposed to require an 

audio-visual change-of-status warning 

whenever a front outboard seat belt is 

unbuckled during a trip (unless a front 

door is open, to account for an occupant 

unfastening the belt to exit the vehicle). 

The warning would be required to 

remain active until the seat belt is 

refastened. 

Proposed Compliance Date 

We proposed a compliance date for 

the amendments to FMVSS No. 208, 

‘‘Occupant crash protection,’’ as 

follows. Manufacturers would be 

required to comply with the 

amendments as of the first September 1 

that is one year after the publication of 

the final rule for the front seat belt 

warning system requirements and the 

first September 1 that is two years after 

the publication of the final rule for the 

rear seat belt warning system 

requirements, with optional early 


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54 49 CFR 571.3 (‘‘Bus means a motor vehicle with 

motive power, except a trailer, designed for carrying 

more than 10 persons.’’) (italics in original). 

55S4.2.7.1. 

56S4.4.3.3; S4.4.5.1. 

57Section 8.4.1.2 (rear seat belt warning 

requirements apply to M1 and N1 category vehicles); 

Consolidated Resolution on the Construction of 

Vehicles (R.E.3) Revision 6, Section 2.2.1 (category 

M1 vehicles) (‘‘Vehicles used for the carriage of 

passengers and comprising not more than eight 

seats in addition to the driver’s seat.’’) and Section 

2.3.1 (category N1 vehicles) (‘‘Vehicles used for the 

carriage of goods and having a maximum mass not 

exceeding 3.5 tonnes [7,716 lb].’’). 

58Section 8.4.1.3. 

compliance. Multi-stage manufacturers 

and alterers would have an additional 

year to comply. 

Regulatory Alternatives 

NHTSA considered alternatives to the 

proposed requirements. The main 

alternatives NHTSA considered were 

the seat belt warning requirements in 

ECE R16 and Euro NCAP. The proposed 

requirements were identical or similar 

to ECE R16 and Euro NCAP in many 

respects but differed from them in 

several ways. For instance, while the 

ECE rear seat belt warning regulations 

allow a warning for an unfastened seat 

belt at an unoccupied seat, the proposal 

would not allow this, because we 

tentatively believed that the resulting 

‘‘false’’ warning would potentially 

annoy drivers and lead to behaviors that 

would decrease system effectiveness. 

Another way the proposal differed from 

ECE R16 is the duration of the front seat 

belt warning on vehicle start-up: R16 

generally requires only a 30–60 second 

audio-visual warning; NHTSA proposed 

a warning that lasts until the seat belt 

is buckled. 

VI. Final Rule and Response to 

Comments 

A. Rear Seat Belt Warning Requirements 

1. Applicability 

The proposal applied to all rear 

designated seating positions in 

passenger cars and all rear designated 

seating positions certified to a 

compliance option requiring a seat belt 

in trucks, buses, and MPVs with a 

GVWR of 4,536 kg (10,000 lb) or less, 

except for school buses and law 

enforcement vehicles. NHTSA’s 

regulations define a bus as a vehicle 

designed for carrying more than ten 

persons.54 The proposal included small 

buses, which refers to buses with a 

GVWR not more than 10,000 lb; this 

therefore includes high-capacity vans. 

However, the proposal did not include 

medium-sized buses (with a GVWR 

10,000 lb–26,000 lb) or large buses (with 

a GVWR greater than 26,000 lb). We 

proposed to apply the proposed 

requirements to the specified categories 

of vehicles because these vehicles are 

required to have seat belts at all rear 

designated seating positions and (except 

for some buses) a seat belt warning for 

the driver’s seat. We noted that some 

types of trucks and MPVs (motor homes, 

walk-in van-type trucks, vehicles 

designed to be sold exclusively to the 

U.S. Postal Service, or vehicles with a 

GVWR between 8,500–10,000 lb 

carrying a chassis-mount camper) 55 and 

over-the-road buses that are also prison 

buses 56 are not required to have rear 

seat belts. In the NPRM we explained 

that we did not propose to exempt 

special-purpose vehicle types such as 

ambulances because NHTSA believed 

that they are typically customized after 

first sale. 

The proposed applicability was 

largely consistent with ECE R16, with a 

few differences. The rear seat belt 

reminder requirements in R16 do not 

include vehicles that carry more than 

nine persons (including the driver).57

There is also no weight specification for 

the passenger vehicles to which R16 

applies. R16 also exempts ‘‘ambulances, 

hearses, and motor-caravans as well as 

for all seats for vehicles used for 

transport of disabled persons, vehicles 

intended for use by the armed services, 

civil defense, fire services and forces 

responsible for maintaining public 

order.’’ 58

Comments 

NHTSA received comments that 

supported the proposal; comments that 

recommended expanding the 

applicability; and comments that 

recommended excluding additional 

vehicle types. 

Some commenters specifically 

supported various aspects of the 

proposal. Freedman Seating Company 

(FSC) and Mr. Koo supported the 

vehicles covered by the proposal and 

Ms. Tombrello supported including vanlike buses because she believed some 

have been prone to misloading of 

passengers and baggage. Mr. Stange 

agreed that the final rule should exclude 

medium and large buses, due to the 

distraction the system would create for 

the driver; problems with maintenance 

and sensor reliability; and the fact that 

bus passengers are not required to wear 

seat belts in some states. 

Some commenters argued for 

including additional higher-capacity 

vehicles that the proposal excluded. The 

National Safety Council (NSC) and Ms. 

Tombrello supported including school 

buses (regardless of weight) and Mr. Koo 

supported including school buses with 

a GVWR 10,000 lb and under. FSC 

supported extending the requirements 

to over-the-road buses with a GVWR 

between 10,000 and 26,000 lb (except 

school, perimeter seating and transit 

buses). NSC commented that the final 

rule should include limousines. 

Relatedly, InterMotive Vehicle Controls 

(InterMotive) commented that it 

manufactures an aftermarket seat belt 

reminder system for buses and vans 

with a GVWR both below and above 

10,000 lb. 

On the other hand, some comments 

argued for excluding additional vehicles 

from the requirements. The Alliance for 

Automotive Innovation (Auto 

Innovators) and Mercedes-Benz and 

Mercedes-Benz Research and 

Development North America (Mercedes) 

recommended exempting vehicles with 

more than six rear seats or more than 

two rear rows, pointing to challenges 

with providing the driver with the 

status information on all seating 

positions via the instrument panel (or 

other in-vehicle display) due to the 

number of seats that may need to be 

displayed. Auto Innovators further 

commented that for high-occupancy 

vehicles with removeable seats, an 

electronic control unit and other 

hardware are needed, which leads to 

practicability concerns, including 

increased costs for customers. Mercedes 

reiterated these practicability concerns. 

The Recreational Vehicle Industry 

Association (RVIA) similarly 

commented that this final rule should 

harmonize with R16 and not apply to 

motor homes. RVIA raised several 

different issues specific to motor homes. 

First, it explained that motor homes are 

used in unique ways because they are 

used both for transportation and for 

temporary, recreational, and seasonal 

use. As an example, RVIA discussed a 

scenario where occupants are seated in 

a rear seating position with the motor 

home turned on, but where the vehicle 

remains stationary, leading to a false 

warning. Second, it commented that 

motor homes’ rear seats are often used 

for storage, which could again lead to 

false warnings. Third, RVIA commented 

that, because motor homes are often 

equipped with non-conventional seats 

that convert into a bed, developing 

wiring and sensors that would not be 

damaged in the conversion process 

would be challenging if not impossible. 

Fourth, RVIA commented that the rear 

portion of a motor home also has its 

own electrical system with very little 

interface with the chassis electronics. 

This lack of interface between electrical 

systems is unique in comparison to 

other types of vehicles that typically 

have seats installed in standard 


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59See, e.g., https://media.ford.com/content/ 

fordmedia/fna/us/en/news/2016/07/29/nothingmini-about-this-van--ford-transit-attracts-largefamilie.html (last accessed May 16, 2024). 

60Belt use rates among occupants in 15-passenger 

vans involved in fatal crashes are significantly 

lower compared to other passenger vehicles. See 

Subramanian, R. (2008). Fatalities to Occupants of 

15-Passenger Vans, 1997–2006. (Report No. DOT– 

HS 810 947). National Highway Traffic Safety 

Administration. 

61See https://www.phoenixseating.com/ourproducts/all-buckled-up and https://

www.fsrtek.com/applications/bus-seat-belt-alarmsystem (last accessed May 16, 2024). 

configurations in the same factory as the 

vehicle is assembled, completed, and 

shipped. RVIA stated that there is 

currently not a way to provide 

electronic signals from the seating 

positions in the rear portion of the 

motor home to the sophisticated 

electronics controls that are proprietary 

to the chassis manufacturers. 

Finally, Braun Northwest (BNW) 

commented that the final rule should 

exempt ambulances, giving essentially 

two different reasons. First, BNW 

commented that the reason NHTSA gave 

for not exempting ambulances—that 

they are typically customized after first 

sale—was factually inaccurate. BNW 

commented that while some specialpurpose vehicles may be customized 

after first sale, that is not the case with 

ambulances. BNW explained that data 

from the Ambulance Manufacturer’s 

Division of the National Truck 

Equipment Association indicates that 

van ambulances with a GVWR under 

10,000 lb, which would be affected by 

this NPRM, comprise more than 20 

percent of the annual production of 

United States ambulance manufacturers. 

Second, BNW pointed out that, while 

circuited buckles needed for seat belt 

buckle status indication are commonly 

available and simple to install on the 

two- and three-point seat belts 

commonly used on most vehicles, they 

are inherently problematic on the four, 

five, and six-point belts needed on 

ambulances. BNW explained that recent 

work facilitated by NHTSA resulted in 

a new SAE International (SAE) 

recommended practice, SAE J3026 

Ambulance Patient Compartment 

Seating Integrity and Occupant 

Restraint, developed specifically for 

testing occupant restraint systems in 

ambulances. All three national 

ambulance standards (KKK–A–1822F, 

Federal Specification: Star-Of-Life 

Ambulance; NFPA 1917 Standard for 

Automotive Ambulances; and CAAS 

Ground Vehicle Standard) now require 

compliance with SAE J3026. BNW 

indicated that the critical ramification of 

SAE J3026 for the NPRM was that sidefacing ambulance bench seats must be 

fitted with four-point, five-point, or sixpoint seat belts. BNW commented that 

there are practicability concerns with 

enabling buckle status indication for 

these seat belts, including the problem 

of getting wires from an emergency 

locking seat belt retractor to a circuited 

buckle located at the center front of the 

occupant’s torso. Additionally, BNW 

argued that seat belt reminders may 

prevent medical personnel from 

administering medical care, as changes 

in occupant position required to render 

patient care would cause alarm 

indications that add distraction and 

confusion in an environment where 

such distractions can have dire 

consequences. 

Agency Response 

NHTSA is adopting the proposal 

except that the final rule contains an 

additional exemption for ambulances. 

The major difference between the 

vehicles to which R16 and the final rule 

apply is that the final rule applies to 

small buses, which typically include 

buses with up to about four rear rows— 

mainly high-capacity passenger vans (10 

to 15-passengers), such as Chevrolet 

Express, Ford Transit, GMC Savana, and 

Mercedes Sprinter passenger vans. 

However, because the rule applies only 

to vehicles with a GVWR less than 

10,000 lb, it would generally not 

include vehicles with more than four 

rows. 

We believe that including small buses 

such as these high-capacity vans 

addresses an important safety need. As 

we explained in the NPRM, we believe 

it is particularly important to include 

vehicles with a GVWR greater than 

3,855 kg (8,500 lb), but less than or 

equal to 4,536 kg (10,000 lb), because 

this range includes high-occupancy 

vehicles. Including these vehicles is 

important because an increasing number 

of high-occupancy vehicles are used as 

personal vehicles and are not solely 

used for work-related purposes.59 In 

addition, multiple rear seats or rows 

make it more difficult for the driver to 

ascertain rear seat belt use, so a warning 

could prove especially useful in these 

vehicles. We think this requirement 

would be especially beneficial for 15- 

passenger vans, for which there is both 

an increased risk of rollover (related to 

the occupancy level of these vehicles) 

and lower seat belt use rates compared 

to other passenger vehicles.60

Providing a reminder in vehicles with 

multiple rear rows is technically 

feasible. As we noted above, because the 

final rule applies to vehicles with a 

GVWR 10,000 lb or less, it generally 

would not include vehicles with more 

than four rear rows of seats, which 

should make it easier to implement a 

reminder. We are unaware of any 

currently produced full-size passenger 

vans having a rear seat belt reminder 

system. We did find aftermarket 

solutions from abroad for medium to 

large buses,61 and InterMotive 

commented that a seat belt warning 

system already exists for multipurpose 

passenger vehicles with a GVWR both 

below and above 10,000 lb. They 

currently manufacture an after-market 

solution, SeatLink, for the bus and van 

market, including seats supplied by 

Freedman Seating Company 

(Freedman). However, we do not have 

any information on the performance and 

reliability of these systems. 

We do acknowledge that vehicles 

such as high-capacity vans may 

encounter visual signal complexities. 

Accordingly, our intent was to propose 

performance requirements that provide 

manufacturers with the flexibility to 

design a warning system that is 

appropriate for each vehicle type (for 

example, the final rule does not require 

a full schematic of the rear seats). For 

example, a visual warning option for 

vehicles with multiple rows could be 

the seat belt icon with an adjacent 

number corresponding to how many 

rear seat belts are fastened. In addition, 

as we explain in more detail below (see 

Section VI.A.2.a.i), in response to the 

comments, we have expanded the 

compliance options to allow additional 

types of visual warning systems. This 

too should help address any concerns 

related to feasibility. 

The final rule, however, also follows 

the proposal in excluding school buses 

and medium and large buses. As we 

explained in the NPRM, extending the 

requirements to school buses would 

place additional cost burden on school 

systems and may result in reductions in 

service; would place additional burdens 

on the driver; and raises liability issues 

and the potential for buses being out of 

service due to malfunctioning systems. 

Many of these concerns were raised by 

commenters to the ANPRM and we 

believe these concerns are still valid. 

Moreover, as we also pointed out in the 

NPRM, school buses use 

compartmentalization, which provides 

protection even to unbelted occupants. 

Similarly, the final rule also excludes 

medium and large buses because of 

issues such as those noted by Mr. 

Stange, including cost, reliability, and 

driver burden. 

The final rule also follows the 

proposal by including motor homes. As 

an initial matter, we note that some 

motor homes are not required to have 


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62 49 CFR 571.3 (definition of ‘‘designated seating 

position’’); FMVSS No. 207 S4.4. 

63 49 CFR 571.3. 

64The Infrastructure, Investment and Jobs Act, 

H.R. 3684, Sections 23015, 23023 (117th Congress) 

(2021), contains two provisions that direct NHTSA 

to conduct research and issue rules (if such rules 

would meet the criteria in section 30111 of the 

Safety Act) related to various aspects of limousine 

crashworthiness and occupant protection. NHTSA’s 

research in these areas is ongoing. See, e.g., DOT 

Regulatory Agenda, Fall 2023, RIN 2127–AM48, 

‘‘Seat Belts in Limousines,’’ available at https://

www.reginfo.gov/public/do/ 

eAgendaViewRule?pubId=202310&RIN=2127-AM48 

(last accessed December 16, 2024). The law also 

directs that the rules issued pursuant to it apply to 

modified vehicles. However, that law also defines 

the term ‘‘limousine’’ to, among other things, refer 

to vehicles weighing between 10,000 and 26,000 lb. 

This would therefore not include any limousines 

that are covered by this final rule, which is limited 

to vehicles up to 10,000 lb. GVWR. 

65This does not exempt ambulances from the 

front seat belt warning requirements. 

66FMVSS No. 201, S3 (definitions). 

67Although section 30122 of the Safety Act 

prohibits making inoperative required safety 

devices, this prohibition does not apply to vehicle 

owners. See infra n. 91 and accompanying text. 

rear seat belts so the requirements will 

not necessarily apply to all motor 

homes. In addition, the seat belt 

requirements do not apply to seats in 

motor homes with a GVWR over 10,000 

lb and classified as MPVs which the 

manufacturer designates and 

conspicuously labels as not intended for 

occupancy while the vehicle is in 

motion.62 Accordingly, such vehicles 

are not subject to the requirements in 

this rule. Although we recognize that 

R16 exempts motor homes (motor 

caravans), we see no reason to exclude 

from this rule designated seating 

positions (DSPs) in motor homes that 

are required to have seat belts. Those 

DSPs are designed to have passengers 

while the vehicle is in motion. Such 

occupants would benefit from a seat belt 

and therefore, from a seat belt reminder. 

We note that if the motor home is 

turned on for other purposes than 

driving, the start-up warning is a 30- 

second visual warning that should not 

be unduly annoying. 

Limousines, depending on their 

characteristics, may also be covered by 

the rule. Limousines are not currently a 

vehicle class defined in the FMVSS. 

Depending on its characteristics, a 

limousine might be classified as a 

passenger car, MPV, or bus.63 Generally, 

a passenger car is designed for carrying 

10 or fewer persons, an MPV is a vehicle 

carrying 10 or fewer persons which is 

constructed either on a truck chassis or 

with certain special features, and a bus 

is designed to carry more than 10 

persons. The final rule encompasses all 

these vehicle types, so a limousine 

would be covered by the requirements 

as long as it weighed 10,000 lb or less. 

At the same time, the FMVSS generally 

apply to new vehicles, including new 

vehicles that are altered, or vehicles 

manufactured in more than one stage. 

Limousines (such as ‘‘stretch’’ 

limousines) that are the result of 

modifications made to a vehicle after 

first purchase other than for resale 

would not be required to be certified to 

the seat belt reminder requirements for 

seating positions that are added in the 

modification process.64

The one way the final rule does 

depart from the proposal with respect to 

the applicability is by including an 

exemption for ambulances from the rear 

seat belt warning system 

requirements.65 Given the information 

provided by BNW, the original intent of 

the rule not applying to ambulances, 

and the fact that excluding ambulances 

harmonizes with ECE R16, the final rule 

exempts ambulances. Although neither 

FMVSS No. 208 nor 49 CFR 571.3 

defines ‘‘ambulance,’’ FMVSS No. 201, 

‘‘Occupant protection in interior 

impact,’’ defines it to mean ‘‘a motor 

vehicle designed exclusively for the 

purpose of emergency medical care, as 

evidenced by the presence of a 

passenger compartment to accommodate 

emergency medical personnel, one or 

more patients on litters or cots, and 

equipment and supplies for emergency 

care at a location or during transport.’’ 66

We are including a cross-reference to 

this definition in the regulatory text. 

However, we have not included a 

broader carve-out for emergency 

vehicles. We did not receive any 

comments indicating that such a carveout was necessary. Moreover, there are 

a number of ways that owners and 

purchasers of emergency vehicles for 

official purposes could disable the 

warnings. These owners and purchasers 

already sometimes alter vehicles 

significantly.67

2. Requirements 

The NPRM proposed a 60-second 

visual warning on vehicle start-up; a 30- 

second audio-visual warning if a 

buckled belt is unfastened during a trip; 

and requirements or criteria related to 

readily removable seats, the owner’s 

manual instructions, the location of the 

telltale, and how NHTSA would 

determine that a belt was or was not in 

use. We discuss these requirements in 

turn below. 

a. Visual Warning on Vehicle Start-Up 

The NPRM proposed a 60-second 

visual warning on vehicle start-up that 

would inform the driver of how many 

or which seat belts are and/or are not in 

use. We proposed three different 

compliance options for the type of 

information conveyed to the driver. 

Occupant detection would not be 

required for one of the three compliance 

options. The warning would be 

triggered when the ignition is placed in 

the ‘‘on’’ or ‘‘start’’ position. When 

testing a system certified to one of the 

compliance options necessitating 

occupant detection, NHTSA would seat 

a dummy or human occupant 

corresponding to a 6-year-old. We 

discuss these proposed requirements 

below in more detail. 

i. Type of Information Conveyed by the 

Visual Warning and Whether Occupant 

Detection Should Be Required 

The proposed requirements for the 

rear seat belt warning system (RSBWS) 

included a visual warning that would 

activate on vehicle start-up to inform 

the driver of the status of the rear seat 

belts. We proposed three different 

compliance options. The first would 

require the system to indicate how 

many or which rear seat belts are in use 

(the ‘‘positive-only’’ option). The second 

would require the system to indicate, for 

the occupied rear seats, how many or 

which rear seat belts are not in use (the 

‘‘negative-only’’ option). The third 

would require the system to indicate, for 

the occupied rear seats, how many or 

which rear seat belts are in use and how 

many or which rear seat belts are not in 

use (the ‘‘full-status’’ option). The 

negative-only and full-status 

compliance options would require that 

the rear seats be equipped with a 

mechanism to determine when a belt 

latch is fastened and an occupant 

detection system (which facilitates these 

more-informative warnings), while the 

positive-only option would only require 

that the rear seats be equipped with a 

mechanism to determine when a belt 

latch is fastened. 

In the NPRM we stated that we had 

tentatively decided not to require 

occupant detection in the rear seats 

because occupant detection continued 

to present technical challenges which 

could reduce the effectiveness and/or 

acceptance of these systems. This 

tentative decision was also based on 

factors such as the needed increase in 

seat belt use for this regulatory 

alternative to have positive net benefits. 

Because we did not propose to require 

occupant detection, we also did not 

propose requiring enhanced warnings 

(such as an audible warning on vehicle 

start-up). 

The proposal harmonized with ECE 

R16 and Euro NCAP in a variety of 

ways, but also deviated from them in 

some respects. 


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68Section 8.4.4.2. 

69Section 8.4.4.2. 

70Section 3.4.3.1.3. 

71Section 3.4.3.1.4. 

72Section 3.4.3.1.1. 

73Seat Belt Reminder System Test and Rating 

Protocol, Version III at pg. 7. 74A supplier of automotive sensing systems. 

ECE R16 requires a visual warning at 

the start of a trip. That warning 

‘‘indicate[s] at least all rear seating 

positions to allow the driver to identify, 

while facing forward as seated on the 

driver seat, any seating position in 

which the safety-belt is unfastened.’’ 68

Occupant detection is not required, but 

in vehicles that do have occupant 

detection the warning does not need to 

indicate unfastened belts for 

unoccupied seating positions.69

The Euro NCAP rating protocol also 

requires a visual warning at the start of 

a trip. The requirements are similar to 

ECE R16. However, Euro NCAP’s rating 

protocol was recently revised to require 

occupant detection in the rear seat to 

receive points for this feature. For 

systems without occupant detection, the 

visual signal must clearly indicate to the 

driver the seating positions showing the 

rear seat belts in use and not in use. 

(These seats would not be eligible for 

points, but in order for seats with 

occupant detection to receive points the 

seats without occupant detection would 

have to meet these requirements.) For 

systems with occupant detection, the 

visual signal does not need to indicate 

the number of seat belts in use or not 

in use, but the signal must remain as 

long as the seat belt remains unfastened 

on any of the occupied seats in the 

rear.70 No signal is required if all of the 

rear occupants are belted 71 or no rear 

occupants are detected.72

The IIHS rating protocol requires a 

visual signal indicating ‘‘whether the 

seat belt at each rear seating position is 

fastened or unfastened.’’ 73

The NPRM acknowledged that the 

proposed compliance options were not 

consistent with all seat belt warning 

systems currently deployed in the U.S. 

and Europe or with Euro NCAP’s 

requirements. Specifically, we noted 

that manufacturers appeared to be 

deploying systems that would be 

categorized as either positive-only or 

negative-only except without occupant 

detection, the latter of which would not 

be permitted under the proposed 

compliance options. We also noted that 

the positive-only compliance option did 

not appear to be consistent with Euro 

NCAP because Euro NCAP requires that 

systems without occupant detection 

show the rear seat belts in use and not 

in use, and the positive-only 

compliance option would not permit a 

visual signal for an unfastened seat belt. 

Accordingly, while we tentatively 

concluded that the proposed 

compliance options would help mitigate 

false warnings and the possibly 

attendant consumer acceptance issues, 

we explained that we were considering 

altering the proposed compliance 

options to accommodate systems that 

are currently being deployed, or that 

manufacturers may wish to deploy in 

the future. 

Comments 

Auto Innovators, General Motors 

(GM), American Honda Motor Co. 

(Honda), and Hyundai America 

Technical Center, Inc. (HATCI) 

generally supported including multiple 

compliance options in the final rule. 

Freedman, Automotive Safety Council 

(ASC), Tesla, Advocates and Public 

Citizen, and the National Automobile 

Dealers Association (NADA) generally 

supported the proposed compliance 

options, although as noted below some 

of these commenters preferred certain 

compliance options or requested that 

additional compliance options be 

added. 

Several commenters (Consumer 

Reports, Safe Kids Worldwide (SKW), 

Paradise, NSC, Safe Ride News (SRN), 

Cross, and Ms. Tombrello) argued that 

NHTSA should require occupant 

detection in the rear seats. Other 

commenters (Freedman, IEE,74 ASC), 

while not explicitly recommending that 

occupant detection be required, either 

preferred options requiring occupant 

detection or focused on the benefits and 

feasibility of rear-seat occupant 

detection. These commenters made a 

variety of arguments. 

Some commenters argued that the 

necessary technology for occupant 

detection is feasible. Consumer Reports 

commented that occupant detection 

does not pose unreasonable technical 

challenges, and is not prohibitively 

expensive (see Section VIII, Overview of 

Costs and Benefits). Consumer Reports 

and Mr. Paradise commented that rearseat occupant detection technology is 

already widely available; Mr. Paradise 

also noted that 7 percent of vehicles 

already have the technological 

capability of occupant detection in rear 

seats. NSC commented that challenges 

with false positives (e.g., transportation 

of cargo and pets) can be addressed 

through a relatively small investment, 

such as with low-cost 2–D or digital 

cameras, and that costs would further 

decrease over time if it were required. 

Consumer Reports noted that occupant 

detection is already widely deployed in 

the front outboard passenger seats. 

Relatedly, although not recommending 

that occupant detection be required, IEE 

commented that today’s occupant 

detection sensors, predominantly 

designed for a detection of 5th 

percentile adult female, can reliably 

differentiate occupants from cargo. 

Several commenters focused on the 

benefits of requiring occupant detection. 

Consumer Reports, Mr. Paradise, SKW, 

SRN, ASC, Ms. Cross, NSC, and Ms. 

Tombrello commented that warning 

systems using occupant detection would 

be more effective than those without it. 

Consumer Reports, Paradise, Ms. Cross, 

and NSC noted that occupant detection 

would enable enhanced warnings, 

which are more effective. 

Accordingly, some of these 

commenters recommended requiring the 

proposed full-status and/or negativeonly options that required occupant 

detection. Consumer Reports argued 

that NHTSA should require the fullstatus compliance option because the 

‘‘positive-only’’ and ‘‘negative-only’’ 

compliance options are insufficient to 

incentivize rear seat belt use. Consumer 

Reports commented that the positiveonly option would be the least 

technically complex, but it would also 

be the least effective type of warning 

system (because it creates unnecessary 

mental work for the driver and allows 

room for human error). Consumer 

Reports further explained that the 

positive-only system would be a 

departure from Euro NCAP, which 

requires that systems without occupant 

detection show both the rear seat belts 

in use and those not in use. Consumer 

Reports also commented that given that 

both the negative-only and the fullstatus options require a belt latch sensor 

and an occupant detection system, the 

negative-only option should be 

eliminated because the full-status 

option is more informative and 

effective. SRN, ASC, NSC, and Ms. 

Cross similarly commented that NHTSA 

should require negative-only or fullstatus systems, which would be more 

effective in alerting caregivers to an 

unbuckled rear passenger than 

‘‘positive-only’’ systems. Ms. Cross 

commented that negative-only and fullstatus systems can inform the driver 

whether any rear seat occupants are 

unbuckled without having to make a 

comparison between number of seats to 

the number of occupants and an audible 

component can be added. ASC also 

noted that permitting only negative-only 

and full-status systems would 

harmonize with the requirements in 

Europe. 


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75Some of the comments were ambiguous with 

respect to whether they were referring to full-status 

systems, negative-only systems, or both. 

76NHTSA does not have any specific information 

on the size of occupant these systems are designed 

to detect. However, based on the manufacturer 

comments requesting that NHTSA require occupant 

detection systems to detect a 5th percentile female 

occupant, it is likely that these systems are 

designed to detect occupants as small as the 5th 

percentile female. 

Consumer Reports, Cross, and SKW 

also recommended requiring occupant 

detection because that feature could 

eventually be used for other safety 

functions such as rear occupant alerts 

for vehicular heatstroke prevention and 

air bag suppression. SKW and Ms. Cross 

pointed to the potential to detect 

children or other vulnerable occupants 

in child safety seats, booster seats, or 

seat belts. 

On the other hand, vehicle 

manufacturers commented that the final 

rule should not require occupant 

detection. Toyota Motor North America, 

Inc. and Toyota Motor Corporation 

(Toyota) and Auto Innovators 

commented that an occupant detection 

system can introduce false positives. 

Several manufacturers requested 

removing the requirement for occupant 

detection from one or both of the 

proposed compliance options that 

required it (full-status and negativeonly). 

Toyota argued that NHTSA should 

allow negative-only systems without 

occupant detection because an occupant 

detection system does not provide any 

additional safety benefit for the 

negative-only system. Toyota explained 

that it is reasonable to anticipate that a 

driver knows whether a rear occupant is 

in the vehicle, and, as with a positiveonly system, can combine that 

knowledge with the information from 

the visual indicator. Toyota also 

commented that a telltale indicating a 

seat belt is not fastened at an 

unoccupied seat is not a false positive, 

but is instead useful information for the 

driver. 

More generally, several manufacturers 

and trade groups (Auto Innovators, Ford 

Motor Company (Ford), Nissan North 

America (Nissan), NADA, Honda, 

Hyundai Motor Company (Hyundai)) 

commented that NHTSA should permit 

manufacturers to convey information on 

positive belt status information (i.e., 

when belt is in use) and/or negative belt 

status information (i.e., when the belt is 

not in use) without occupant 

detection—that is, NHTSA should 

expand the proposed compliance 

options to permit negative-only systems 

without occupant detection and/or fullstatus systems without occupant 

detection.75 NADA argued that these 

options would provide better contextual 

information for drivers than the 

proposed full-status option because they 

would provide seat belt status 

information for all seating positions 

regardless of occupancy. Nissan, Ford, 

and Auto Innovators argued that 

presenting information on the seat belt 

status regardless of whether the seat is 

occupied or not should not be deemed 

as misleading but rather as furnishing 

the driver with pertinent contextual 

information concerning seat belt usage 

across all positions. Nissan and Ford 

argued that this information would 

empower the driver to distinguish easily 

between buckled and unbuckled seat 

belts, particularly when compared to the 

locations where known passengers are 

situated in the rear row. Auto 

Innovators, Nissan, NADA and Ford 

commented that this approach would be 

consistent with European regulations. 

Nissan, NADA, and Ford indicated that 

this approach would align with ECE 

R16, and Ford and Auto Innovators 

commented that the approach aligns 

with the IIHS approach. Honda 

commented that systems without 

occupant detection that provide visual 

information on both fastened and 

unfastened seat belts have been in use 

in Europe for many years and are well 

understood by those that use it 

regularly. Auto Innovators and NADA 

commented that not expanding the 

compliance options in this way would 

require development and deployment of 

new systems and increase cost and lead 

time for some original equipment 

manufacturers (OEMs), which 

ultimately harms consumers and 

hinders achievement of NHTSA’s safety 

objective. Auto Innovators further 

commented that it was unaware aware 

of any data that would support 

NHTSA’s claim that a visual indication 

of an unfastened seat belt at an 

unoccupied seat would annoy drivers 

and argued that if driver annoyance is 

a concern, NHTSA should consider 

allowing a dismissible initial warning, 

as is the case with both IIHS and R16. 

In addition, Ford, Toyota, and Honda 

raised concerns with the proposed 

positive-only compliance option. Ford 

and Toyota commented that it conflicts 

with R16 and the IIHS protocol. Honda 

commented that if all rear occupants are 

unbuckled and there is no indication of 

their status, the driver may remain 

unaware of the system’s ability to 

support the determination of the 

statuses of the belts for the rear 

occupants. 

Agency Response 

In response to the comments, the final 

rule follows the proposal in not 

requiring occupant detection, but 

modifies the proposal by revising the 

requirements to allow full-status and 

negative-only reminder systems without 

occupant detection. 

The final rule follows the proposal in 

not requiring that rear seat belt reminder 

systems be equipped with occupant 

detection. There are a few reasons for 

this decision. 

One reason is that we believe rear-seat 

occupant detection continues to present 

technical challenges. This is especially 

the case because we have concluded 

that rear-seat occupant detection 

systems should be able to detect, at a 

minimum, occupant characteristics 

matching a 6-year-old for determining 

whether a rear seat is occupied. This 

standard differs from ECE R16 and Euro 

NCAP, both of which base their 

requirements for occupant detectionequipped rear seat belt reminder 

systems on the 5th percentile female. 

This difference is discussed in more 

detail in Section VI.A.2.a.iv, Seat 

Occupancy Criteria and Interaction with 

Child Restraint Systems. Rear-seat belt 

reminder systems with occupant 

detection have only been recently 

deployed in vehicles sold in the U.S. 

(starting in MY 2021 based on our 

available data) and are currently offered 

on only a small proportion of new 

vehicles.76 Based on the projected sales 

for MY 2022, approximately 7 percent of 

vehicles were equipped with rear-seat 

occupant detection. We have no data on 

how the occupant detection in these 

vehicles is working. 

While occupant detection technology 

is readily available and standard 

equipment in most front outboard 

passenger seats, the occupant detection 

technology used for the front outboard 

passenger seat does not necessarily 

translate directly to the rear seats. By 

comparison, vehicles subject to 

advanced air bag requirements comply 

using either suppression or low-risk 

deployment for different size child 

dummies, including the 6-year-old child 

dummy, in the front outboard passenger 

seat. Vehicles with a suppression 

system use some type of occupant 

detection technology in addition to 

other inputs (e.g., seat belt use, seat 

position, etc.) to determine whether or 

not to deploy the air bag. Vehicles using 

low-risk deployment, however, do not 

necessarily need to use occupant 

detection to meet the advanced air bag 

requirements for that option. The vast 

majority of vehicles use the suppression 

option in the front outboard passenger 


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77There is also an option to use a dynamic 

automatic suppression system. To date, no 

manufacturer has attempted to certify using this 

option. 

78With respect to the driver’s seat, while it is 

subject to certain advanced air bag requirements, 

those particular requirements do not necessitate 

occupant detection. 

79With respect to SKW’s comments about the 

benefits of monitoring children in forward- or rearfacing CRSs, as we explained in the NPRM, 

children restrained by child restraint systems are 

not part of the target population for this rule. 

seat for at least one child dummy, and 

therefore use occupant detection.77 78

Vehicle manufacturers that opt to use 

a rear seat belt warning system with 

occupant detection will have to develop 

and implement occupant detection 

solutions that work for the unique seat 

designs and configurations found in rear 

seats (e.g., bench seats, folding seats, 

different types of seat cushions, etc.) 

and validate the performance to ensure 

that they meet the new requirements 

and mitigate the potential for false 

positives. Among other challenges, rear 

seats create more potential for false 

positives than the front seats. As we 

explained in the NPRM and ANPRM, 

while occupant detection can reduce 

false warnings for unoccupied seats, it 

can also result in false warnings, due to 

the limitations of the sensors and 

different use scenarios in the rear seats 

(e.g., transportation of cargo and pets). 

In addition, rear seats may be less welldefined than front seats (most rear seat 

rows, unlike the front seat rows, are 

comprised of three closely spaced 

seating positions), which could impede 

accurate detection. This deficiency 

could negatively affect consumer 

acceptance and/or effectiveness. 

Another reason the final rule does not 

require occupant detection is that it 

adds non-trivial costs to the seat belt 

warning system. While we agree with 

Consumer Reports that rear-seat 

occupant detection is not prohibitively 

expensive in the sense that this is true 

for some vehicle lines, our cost-benefit 

analysis shows that occupant detection 

would be cost-beneficial only if rear seat 

belt use increased substantially more 

than we estimate it would for a warning 

system without occupant detection. Our 

teardown analysis indicates that 

occupant detection components cost 

$39.74 per vehicle, which, added to the 

$19.59 per vehicle cost of the buckle 

sensor, results in a combined warning 

system cost of $59.33 per vehicle (2020 

$). We estimate that the total new fleet 

cost of a rear seat belt warning system 

with occupant detection would be about 

$802 million (2020 $). With respect to 

benefits, there is uncertainty with 

respect to how much more effective 

systems with occupant detection are 

compared to systems without it. 

Because of this uncertainty, our 

regulatory analysis does not attempt to 

estimate the net benefits or costeffectiveness of rear seat belt reminder 

systems that use an occupant detection 

system. The regulatory analysis does, 

however, include a break-even analysis 

for a rear seat belt reminder system that 

requires occupant detection. For 

benefits and costs to break even (be 

equal) for this regulatory option, seat 

belt use for rear seat occupants 11 years 

and older would need to increase by 

approximately 5.2 percent when 

discounted at 3 percent and 6.4 percent 

when discounted at 7 percent. 

Furthermore, NHTSA considered the 

increase in seat belt use for rear seat 

occupants that would be required to 

match the net benefits under the final 

rule, which does not require occupant 

detection. When discounted at three and 

seven percent, seat belt use for rear seat 

occupants 11 years and older would 

need to increase by 6.43 percent to 8.57 

percent to match the net benefits (taking 

into account the Low and High 

estimates) under the final rule. This is 

about two to three times greater than 

that estimated for the compliance option 

without occupant detection. (For more 

details, see Section VIII.B.1 and the 

FRIA.) Accordingly, while we agree 

with the commenters who supported a 

requirement for occupant detection 

because there may be benefits to having 

occupant detection (such as facilitating 

enhanced or more effective warnings) 79

and would expect some potential 

increase in seat belt use from that 

specific functionality, an effectiveness 

increase of this order of magnitude 

seems unlikely. Therefore, we do not 

expect this regulatory alternative to be 

net beneficial and would not generate 

the same level of net benefits as the final 

rule. Manufacturers may voluntarily 

equip vehicles with occupant detection 

if they so choose. Our hope is that over 

time, as the systems evolve and 

penetrate the fleet, the technology will 

mature and per-unit costs will decrease. 

With respect to the comment from Mr. 

Paradise concerning what he believed 

was an inconsistency between NHTSA’s 

statements that a single-digit percentage 

of vehicles with rear-seat occupant 

detection being a small percentage of 

the fleet, and weighing in favor of not 

requiring it, and a single-digit 

percentage of vehicles with an 

indefinite reminder being non-trivial 

and supporting our proposal to require 

an indefinite reminder for the front seat 

belt start-of-trip warning, we do not 

believe these statements are 

inconsistent. In the context of occupant 

detection, we are referring to 

technological feasibility and likely 

regulatory cost; in the front seat belt 

warning section, we are referring solely 

to the optimum duration, as there is no 

question about feasibility. That is, a 

single-digit percentage has a different 

meaning in the two contexts. 

Because we have decided not to 

require occupant detection, we 

disagreed with commenters who 

recommended requiring one or both of 

the proposed options that required 

occupant detection (full-status with 

occupant detection or negative-only 

with occupant detection). We continue 

to believe, as we explained in the 

NPRM, that while the full-status system 

(with occupant detection) does provide 

the driver with the most information, 

the other allowable types of systems, 

including those without occupant 

detection, will provide the driver with 

sufficient information to easily 

determine whether and where there are 

any unbuckled occupants and request 

that they fasten their seat belts. 

Accordingly, the final rule allows the 

proposed positive-only option. These 

systems, while not providing 

information on the occupancy status of 

each seat, do provide information on 

which seat belts are buckled. The driver 

can combine this information with 

knowledge of the other occupants in the 

vehicle and determine if there are any 

unbuckled occupants and request them 

to fasten their belts. While this does 

require mental work on the part of the 

driver, and may not be as effective as a 

full-status system, we believe it is not so 

burdensome as to render such systems 

ineffectual to such a degree that we see 

a basis for prohibiting them. While such 

systems are not permitted under ECE 

R16 or Euro NCAP, manufacturers could 

select another type of system if they 

wished to harmonize with those 

protocols. (The positive-only system 

without occupant detection does 

conform with the IIHS protocol.) With 

respect to Honda’s comment that the 

proposed positive-only option could 

potentially leave the driver unaware 

that the vehicle was equipped with a 

seat belt reminder system, we 

acknowledge that is a possibility, but it 

would not be a long-term problem. This 

would be limited to times when a driver 

is driving a vehicle new to them (unless 

the driver always reads owner’s 

manuals first) and would only be an 

issue until a rear passenger buckles up. 

Once a rear passenger buckles up the 

driver would become aware of the 

existence of the warning. 

We have modified the proposal so 

that the final rule does not dictate 


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80See Mark Freedman et al., Effectiveness and 

Acceptance of Enhanced Seat Belt Reminder 

Systems: Characteristics of Optimal Reminder 

Systems Final Report. DOT HS 811 097 at pg. 49 

(Feb. 2009) (hereinafter ‘‘DOT 2009 Seat Belt 

Study’’). 

81An exception is a positive-only system with 

occupant detection, which is not prohibited by the 

finalized requirements and has yet to be deployed 

on vehicles sold in the United States. However, we 

believe it would be unlikely that a manufacturer 

would deploy such a system because the presence 

of occupant detection allows for more informative 

reminders—for example, a full-status reminder— 

than provided by a positive-only system. This is 

reflected in the fact that while we are aware of 

production versions of positive-only systems 

without occupant detection, negative-only and fullstatus systems with and without occupant 

detection, we are not aware of any vehicle equipped 

with both occupant detection and a positive-only 

reminder system. 

82The language relating to EVs is discussed in 

Section VI.C.1. 

specific compliance options for the 

information conveyed by the visual 

warning; the finalized requirements for 

the visual warning allow all of the 

systems that would have been allowed 

under the proposed rule, as well as 

additional systems that would not have 

been allowed under the proposal, such 

as a negative-only system without 

occupant detection, and a full-status 

system without occupant detection. 

Both the negative-only system without 

occupant detection and the full-status 

system without occupant detection are 

consistent with ECE R16 and the IIHS 

protocol (they would not be eligible for 

points under Euro NCAP). One factor 

underlying this choice is the lack of firm 

research data that could lead NHTSA to 

meaningfully compare the effectiveness 

of the different types of systems,80

coupled with the fact that rear seat belt 

reminder systems conforming to the 

finalized requirements have already 

been deployed on vehicles sold in the 

United States.81 These factors make us 

reluctant to prohibit particular design 

choices and inhibit manufacturer 

flexibility and ability to optimize system 

characteristics. We believe that the 

finalized regulatory text (‘‘A visual 

warning indicating how many or which 

rear seat belts are in use and/or not in 

use must activate when the ignition 

switch is placed in the ‘on’ or ‘start’ 

position (or upon manual activation of 

the propulsion system, but prior to the 

vehicle being placed in ‘‘possible active 

driving mode’’ as defined by FMVSS 

No. 305))’’ 82 includes all of the systems 

manufacturers are currently deploying, 

but is specific enough to be objective 

and enforceable. For example, if there is 

one rear occupant, and that occupant is 

belted, a positive-only system without 

occupant detection that accurately 

indicates one buckled rear belt, and a 

full-status system with occupant 

detection that accurately indicates one 

rear occupant with a fastened belt, 

would both comply with the finalized 

regulatory text. 

We agree with Toyota and Honda that 

the negative-only system requires the 

same cognitive effort on the part of the 

driver as the proposed positive-only 

option, and that it would still be 

effective and beneficial, even without 

occupant detection. We no longer agree 

with the view we expressed in the 

NPRM that such a signal is a false 

positive that might either desensitize 

the driver to the warning signal or lead 

them to circumvent or defeat the 

system. We now agree with Toyota that 

this is instead more accurately 

considered relevant information on seat 

belt status that the driver can use to 

determine whether there are any 

unbuckled occupants and request them 

to fasten their seat belts. 

We reached a similar conclusion with 

respect to full-status systems without 

occupant detection. As we discussed 

above for the negative-only systems 

without occupant detection, we agree 

that while this system does not provide 

as much information as would a system 

with occupant detection, the 

information it does provide on the seat 

belt status at every seating position 

(occupied or not) is useful information 

for the driver. We also agree with the 

commenters who argued that allowing 

this option would support the 

introduction of systems that are already 

in widespread use, without adding in 

additional cost and complexity. 

ii. Lack of an Audible Warning 

The NPRM recognized that warnings 

with an audible component are 

generally more effective than visualonly warnings. However, we also 

recognized that requiring an audiovisual warning would necessitate 

requiring occupant detection because, 

without occupant detection, an audible 

warning would activate every time a 

rear seat is empty. These ‘‘false 

positives’’ would annoy the driver (as 

well as other occupants) and would 

decrease the effectiveness of the 

warning. Thus, the NPRM did not 

propose an audible warning on start-up. 

However, manufacturers would be free 

to provide an audible warning on startup if they so choose. This approach is 

also consistent with ECE R16, Euro 

NCAP, and IIHS. 

Comments 

Many of the commenters who 

supported requiring occupant detection 

also supported requiring an audible 

warning (NSC, Consumer Reports, SRN, 

Karleigh Cross, and an anonymous 

commenter). SRN, Consumer Reports, 

and Ms. Cross commented that audible 

warnings are more effective than visualonly warnings. Consumer Reports also 

commented that requiring an audible 

component to the rear seat start-up 

warning would also make start-up 

warnings more consistent throughout a 

vehicle, regardless of the seating 

position. 

Agency Response 

The final rule does not require a rear 

seat audible start-of-trip warning, for the 

reasons articulated in the proposal. 

Because the final rule does not require 

occupant detection in the rear seats, it 

does not require an audible warning. We 

acknowledge that audio-visual warnings 

are more effective than visual warnings 

alone, and we believe that consumers 

would accept them. However, we 

believe that a visual warning alone will 

still be effective. While we cannot 

precisely estimate effectiveness, we 

have used a three to five percent belt 

use rate increase range (‘‘lower’’ and 

‘‘higher’’ scenario) in our analysis based 

on the available research. This analysis 

is explained in detail in the FRIA. We 

agree that in general, consistency 

between the rear reminder and front 

reminder requirements (which do 

require an audio-visual start-of-trip 

warning) is desirable, but do not believe 

that not requiring an audible component 

to the rear start-of-trip warning will 

create an issue in practice. In this 

context, the relevant potential concern 

with this inconsistency is that the 

driver—the recipient of the warning— 

would be confused or annoyed by any 

differences in the two warnings. 

Ultimately, we do not believe this 

inconsistency is a significant problem. 

The front seat belt warnings have been 

in vehicles for many years. Rear seat 

belt warnings will be new to most 

drivers, so drivers will have to become 

accustomed to them. In addition, the 

rear reminder will be a fairly prominent 

visual warning. If the driver is unsure of 

how the warnings operate, this rule also 

requires that the owner’s manual 

include an accurate and easily 

understandable description of system 

features and operation. 

iii. Triggering Conditions for Start-ofTrip Warning (Not Including Occupant 

Detection Criteria) 

The NPRM proposed that the rear seat 

start-of-trip warning (which, as 

discussed above, is only required to be 

a visual warning) activate when the 

ignition switch is placed in the ‘‘on’’ or 

‘‘start’’ position, except for negativeonly systems when there are no 

occupied rear seats with a seat belt not 


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83Section 8.4.2.3.1. 

84Section 8.4.4.2. 

85Section 3.4.1. 

86Section 3.4.2.1 (front); § 3.4.3.1.1 (rear). 

87Section 3.4.1. 

88Section 3.4.3.1.3. 89See DOT 2009 Seat Belt Study at pg. 65. 

in use (for which we proposed that a 

warning not be required to activate). 

The activation criteria were modeled on 

the existing driver seat belt warning 

requirements and are also similar to 

those in ECE R16, Euro NCAP, and the 

IIHS protocol. 

ECE R16 requires that the rear seat 

belt visual warning activate when a belt 

is not fastened and the ignition or 

master control switch activated.83 It also 

provides that for vehicles with rear seat 

occupant detection, the visual signal 

does not need to indicate unfastened 

belts at unoccupied seats.84

Euro NCAP similarly requires that the 

warning ‘‘‘start’ at the commencement 

of each ‘journey’ that the vehicle 

makes.’’ 85 More specifically, the Euro 

NCAP protocol specifies that the visual 

signal be activated ‘‘when the ignition 

switch is engaged (engine running or 

not) and a seatbelt is not fastened.’’ 86

However, Euro NCAP allows for short 

breaks in the journey (up to 30 seconds) 

to account for events such as engine 

stalling where the reminder is not 

required to start again.87 Euro NCAP 

also provides that for systems with rear 

seat occupant detection, the visual 

signal does not need to indicate the 

number of rear seat belts in use or not 

in use.88

For the rear seats, the IIHS protocol 

permits a 10-second delay between the 

ignition being turned on and the 

activation of the visual signal. Similar to 

ECE R16 and Euro NCAP, no visual 

signal is required for the rear seat belts 

if there are no unfastened belts at 

occupied seats. 

The major differences between the 

proposal and other approaches were 

that, unlike ECE R16, we did not 

propose to refer to a ‘‘master control 

switch’’ because we did not believe it is 

necessary to introduce this new term 

into FMVSS No. 208; unlike Euro NCAP 

we proposed not allowing for short 

breaks in the journey; and unlike IIHS 

we did not propose allowing any delay 

after the ignition was turned on. 

Comments 

Commenters differed on whether the 

start-of-trip warning should be 

permitted to be delayed. HATCI and 

Ford supported the proposed trigger 

conditions (which did not permit a 

delay). On the other hand, Auto 

Innovators, NADA, Freedman, and 

Nissan recommended allowing a delay. 

Nissan, Auto Innovators, and NADA 

recommended aligning with the IIHS 

protocol and permitting a 10-second 

delay, while Freedman favored a 30- 

second delay. Auto Innovators also 

commented that while it generally 

supports the agency harmonizing with 

ECE R16, the agency should maintain 

flexibility for when these warnings are 

displayed on startup and allow for a 

brief delay for when the alert is 

provided. Freedman also commented 

that certain systems, such as an 

electronic system separate from that of 

the OEM system, will require a powerup 

and boot cycle which can take several 

seconds. 

Auto Innovators also requested that 

the final rule allow the visual warning 

to be suppressed if all rear row seating 

positions are belted or determined to be 

empty based on occupant detection. 

Lastly, RVIA explained that motor 

homes can be used in many ways other 

than for transportation, such that the 

ignition may be turned on with 

occupants seated in the rear accessing 

the vehicle’s amenities, but with no 

intention of placing the vehicle in 

motion. RVIA was concerned that such 

use of the rear seats would trigger the 

rear seat belt visual warning, even 

though the motor homeowner has no 

intention of operating the vehicle. RVIA 

concluded that a visual warning system 

on vehicle start-up would often go 

unnoticed in this scenario, creating a 

requirement not suitable for the 

application of the start-up trigger in a 

motor home. 

Agency Response 

The final rule adopts the proposal for 

the warning to activate on start-up, with 

no provision for a delay. We continue to 

believe that basing the trigger on the 

ignition switch is preferable to delaying 

the warning until the vehicle is placed 

in gear because with a delay, there 

could be instances where a driver would 

pull out onto the road before the 

warning starts and before passengers 

have belted. The finalized requirements 

increase the likelihood that the 

occupants fasten their belts before the 

vehicle is in motion.89 With respect to 

mitigating interaction with other vehicle 

warnings, NHTSA does not believe this 

will be an issue at vehicle start-up 

because critical safety warnings that 

activate at start-up would likely have 

dedicated space on the display. 

Interactions between warnings is 

discussed in more detail in Section 

VI.C.4. We believe consumers will 

accept this start-up warning. The 

longstanding current front seat belt 

warning is based on similar triggers and 

has not caused any issues. In addition, 

the rear start-of-trip warning is visualonly, so any potential annoyance is 

minimized. This factor distinguishes the 

rear-seat warning from the front seat belt 

warning, which we are requiring to be 

both audio-visual and to have two 

phases. We acknowledge there may be 

some scenarios during a trip where a 

rear seat belt warning is not required for 

an unbuckled occupant; for example, a 

passenger pickup scenario when the car 

is not turned off. In such a scenario, we 

are not requiring a warning because we 

are not requiring occupant detection, 

which would be necessary to detect the 

new occupant (and potentially avoid a 

false warning). Manufacturers of 

vehicles with rear-seat occupant 

detection may choose to provide 

warnings for such situations. 

In addition, we are modifying the 

proposed trigger condition related to the 

vehicle ignition being in the ‘‘on’’ or 

‘‘start’’ position for both the front and 

rear seat belt warning to better account 

for EVs. This change is discussed in 

Section VI.C.1. This modification 

generally harmonizes with ECE R16, 

Euro NCAP, and the IIHS protocol, so 

that a vehicle that complies with the 

finalized trigger requirements can still 

meet these requirements; some 

exceptions are discussed immediately 

below. 

In addition, we have also modified 

the proposal so that the final rule does 

not require a visual warning in three 

circumstances: (1) for an unoccupied 

seat if the system is able to determine 

whether a seat is occupied; (2) for a seat 

belt that is in use in a system designed 

to indicate to the driver how many or 

which rear seat belts are not in use; and 

(3) for a seat belt that is not in use in 

a system designed to indicate to the 

driver how many or which rear seat 

belts are in use. This regulatory text is 

intended to clarify two things. 

First, that, depending on the type of 

seat belt reminder system and belt use/ 

occupancy scenario, a visual signal may 

not be necessary for a particular DSP, or 

may not be necessary for any DSP. So, 

for example, no visual warning would 

be required for a negative-only system 

when every rear seat is occupied by a 

belted occupant. Another example: if no 

rear seats are occupied, no visual signal 

is required for negative-only, positiveonly, or full-status systems with 

occupant detection; a visual warning 

would, however, be required in this case 

for a negative-only system without 

occupant detection (assuming that no 

rear belts were in use) and a full-status 

system without occupant detection. 


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90See also Section VI.C.3, Visual Warning 

Characteristics. 91 49 U.S.C. 30122(b) (‘‘A manufacturer, 

distributor, dealer, rental company, or motor 

vehicle repair business may not knowingly make 

inoperative any part of a device or element of 

design installed on or in a motor vehicle or motor 

vehicle equipment in compliance with an 

applicable motor vehicle safety standard prescribed 

under this chapter unless the manufacturer, 

distributor, dealer, rental company, or repair 

business reasonably believes the vehicle or 

equipment will not be used (except for testing or 

a similar purpose during maintenance or repair) 

when the device or element is inoperative.’’); 

section 30122(a) (‘‘(a) Definition. In this section, 

‘‘motor vehicle repair business’’ means a person 

holding itself out to the public to repair for 

compensation a motor vehicle or motor vehicle 

equipment.’’). 

92See Section VI.C.1. 

This requirement is consistent with ECE 

R16, Euro NCAP, and IIHS. 

Second, this also clarifies, in response 

to the comments, that systems utilizing 

symbols or numbers may utilize colors 

other than green or red to indicate 

unoccupied seats or seating positions 

for which the system is not providing 

information on belt use. Accordingly, a 

negative-only system would be 

permitted to display a pictogram that 

denotes a seating position with an inuse belt as grayed-out (to give one 

example).90

Freedman’s comment regarding 

certain vehicles requiring more time to 

boot up appears to be referring to 

accommodating aftermarket systems. 

Because the final requirements apply to 

vehicles before first purchase other than 

for resale, they do not directly apply to 

aftermarket systems that are installed 

later on. However, § 30122 of the Safety 

Act prohibits a vehicle modifier from 

taking a vehicle out of compliance with 

an applicable FMVSS.91 (The vehicle 

owner is not subject to the make 

inoperative provision). Therefore, a 

vehicle modification performed after the 

compliance date of this final rule on a 

vehicle with a rear seat belt warning 

system certified to the requirements in 

this rule that modifies the vehicle such 

that the rear seat belt visual warning 

does not activate when the ignition is in 

the ‘‘on’’ or ‘‘start’’ position (or upon 

manual activation of the propulsion 

system, but prior to the vehicle being 

placed in ‘‘possible active driving 

mode’’ as defined by FMVSS No. 305) 92

would violate § 30122 and would 

therefore not be permitted. 

The final rule does not incorporate 

RVIA’s request to accommodate use 

scenarios specific to Recreational 

Vehicles (RVs). We agree that in the 

scenarios identified by RVIA the 

warning would activate when the 

vehicle was turned on with no intent to 

drive (thus obviating the need for a seat 

belt). A speed or motion trigger could 

address this issue, but we believe that 

such a trigger is undesirable because 

there is a safety benefit to having 

occupants belted before the vehicle is in 

motion or when it is travelling at lower 

speeds. Moreover, because the rear seat 

belt start-of-trip warning is visual-only, 

there are not the same consumer 

acceptance concerns that led us to 

include a speed criterion like we have 

included for the second-phase front seat 

belt audible warning. (See Section 

VI.B.3.) We could also potentially 

address this concern by either 

exempting RVs or crafting trigger 

criteria specific to RVs. We conclude the 

former is undesirable due to the 

significant safety benefit of belts when 

the vehicle is in motion, and that the 

latter would be overly complex. In 

addition, the rear seat belt start-of-trip 

warning is a mild visual warning that 

should not cause meaningful consumer 

annoyance (or condition them to ignore 

the warning) in these use cases. 

iv. Seat Occupancy Criteria and 

Interaction With Child Restraint 

Systems 

For rear seat belt warning systems that 

manufacturers voluntarily choose to 

equip with occupant detection, NHTSA 

proposed the occupancy criteria for the 

test dummy (or human, at the 

manufacturer’s option) that NHTSA 

would position in the seat to conduct 

compliance testing of the system. 

NHTSA proposed that a rear designated 

seating position would be considered 

‘‘occupied’’ when an occupant who 

weighs at least 46.5 lb (21 kg), and is at 

least 45 in (114 cm) tall, is seated there. 

These criteria are proxies for a 6-yearold child, which roughly corresponds to 

a typical age at which a child would 

begin using a seat belt (with a booster 

seat), transitioning from a forwardfacing child restraint system (CRS). 

These are the same criteria used in 

FMVSS No. 208 to specify the smallest 

child that may be used as an alternative 

to the 6-year-old dummy in static 

suppression tests under FMVSS No. 

208. We proposed using either a human 

being, at the manufacturer’s option, or 

any anthropomorphic test device 

specified in 49 CFR part 572 that meets 

these proposed weight and height 

criteria (Section VI.C.8., Test 

Procedures). 

The proposed criteria corresponded to 

a smaller occupant than ECE R16 or 

Euro NCAP, each of which essentially 

specifies an occupant (or load) no 

smaller than a 5th percentile adult 

female (e.g., the HIII–5F specified in 49 

CFR part 572). In the NPRM we 

explained that we believed that 

harmonizing with ECE R16 and using a 

heavier dummy would not capture the 

child segment of the population that 

could be restrained with a seat belt. We 

also did not believe it was necessary to 

use a larger-size occupant because a 

system capable of recognizing a 6-yearold should also be capable of 

recognizing larger occupants. 

At the same time, we tentatively 

believed that the proposed criteria were 

preferable to criteria reflecting a 

younger occupant (lower weight). The 

smallest dummy that would meet the 

proposed weight and height criteria is 

the 6-year-old dummy specified in part 

572. The next smallest dummy 

represents a 3-year-old child (i.e., the 

Hybrid III 3-year-old); we believed it 

would not be appropriate to specify the 

use of the 3-year-old because a child 

represented by this dummy should be 

seated in a forward- or rear-facing CRS, 

not restrained with a seat belt. 

NHTSA did not propose to require 

any sort of CRS detection capabilities. 

As explained in the NPRM, there are 

essentially three types of CRSs: rearfacing CRSs, forward-facing CRSs, and 

booster seats. Rear-facing and forwardfacing CRSs are child seats that are 

installed using either Lower Anchors 

and Tethers for Children (LATCH) or a 

seat belt to secure it in place. Booster 

seats raise and position a child so the 

vehicle’s lap-and-shoulder belt fits 

properly. We tentatively believed that a 

forward- or rear-facing CRS installed 

with the seat belt would not cause 

problematic false warnings; rather the 

system would just register the CRS as a 

buckled passenger. Similarly, we 

believed that a forward- or rear-facing 

CRS installed with LATCH would not 

pose issues necessitating any specific 

requirements related to the LATCH 

system, such as LATCH sensors. 

We also did not believe a booster seat 

would present any special challenges to 

a seat belt warning system. If an 

unbelted child is in a booster seat, the 

system would register the belt as not 

fastened and, if equipped with occupant 

detection, that the seat was occupied. 

The system would not have to 

specifically detect the booster seat 

because the performance criteria are 

weight-based. In addition, we would not 

expect an occupant detection system to 

provide a false warning for an 

unoccupied booster seat because the 

proposed seat occupancy criterion 

(roughly equivalent to a 6-year-old) is 

heavier than an unoccupied booster 

seat. We did not propose to specify the 

use of a booster seat for testing because 

children may be prematurely 

transitioned to a seat belt without the 

use of a booster, and we believe it is 

desirable to test the lower end of the 


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possible weight range that encompasses 

children that could conceivably be 

restrained with a seat belt. 

Comments 

A number of commenters (Auto 

Innovators, Mercedes, GM, NADA, IEE, 

Honda, HATCI, and Consumer Reports) 

disagreed with the proposal and 

recommended harmonizing with ECE 

R16 and Euro NCAP and specifying 

occupancy criteria based on a 5thpercentile adult female occupant. These 

commenters made a variety of 

arguments. 

Auto Innovators commented that 

harmonizing with the ECE requirements 

would avoid introducing unnecessary 

complexity and reduce the need for 

additional lead time to develop U.S.- 

specific designs. IEE commented that 

the proposed detection criterion would 

entail significant additional costs. 

IEE also commented that a detection 

criterion based on the 5th percentile 

female would address the key target 

population of unbelted teenagers and 

adults. Relatedly, IEE noted that the 

NPRM analysis investigated potential 

benefits for the age group 6 to 10 years 

old and only found a very small belt 

usage increase (by only 0.27 percent to 

0.41 percent) and concluded that 

members of this age group already have 

high rates of seat belt use (98 percent 

according to the preliminary regulatory 

impact analysis). 

Consumer Reports, IEE, Auto 

Innovators, Honda, HATCI, NADA, 

RVIA, and GM raised concerns 

regarding feasibility. Consumer Reports 

agreed with NHTSA on the importance 

of testing the lower end of the possible 

weight range that encompasses children 

that could conceivably be restrained 

with a seat belt alone, but believed that 

it would be premature to require the 

detection of dummies smaller than the 

5th percentile adult female because the 

ability to detect occupants smaller than 

the 5th percentile adult female is 

limited. IEE commented that while 

detecting a 5th percentile female is wellestablished in the market and would not 

present any design or technical 

challenges, it was not aware of any car 

on the market that would be able to 

meet the proposed detection of the 6- 

year-old child scenarios, with or 

without a booster cushion. IEE 

commented that the 5th percentile 

female is the state-of-the art in 

contemporary sensing technology for 

seat belt reminder-related occupant 

detection and that no realistic 

alternative technologies are readily 

available at comparably low costs. IEE 

stated that it believed that the 7 percent 

of U.S. MY 2022 vehicles with rear seat 

occupant detection all meet the 5th 

percentile female detection criterion, 

not the one 6-year-old proposed in the 

NPRM. 

IEE also commented that the proposal 

assumed that a 6-year-old child on the 

booster seat would be automatically 

covered and detected as it has a higher 

total weight than the weight proposed 

for the occupancy criteria. IEE stated 

that this assumption is wrong: rear 

occupant detection systems are 

designed to detect a load that is 

generating a pressure profile on the seat 

foam that matches the pressure profile 

of a human buttocks. IEE commented 

that the pressure profile generated by a 

booster seat is different and would not 

be classified by the system as an 

occupant; contemporary occupant 

detection sensors used for seat belt 

reminder systems are not designed to 

detect booster seats, and child seats are 

considered as non-detection objects. IEE 

indicated that this distinction is also 

required to differentiate between 

humans and objects, to avoid objects 

that would be likely to trigger false 

positives. Auto Innovators similarly 

commented that the contact area 

between a booster seat and a seat 

cushion can vary, causing some of the 

occupant’s weight to be distributed to 

the seat itself or to the LATCH system, 

rather than to the weight sensor. 

Auto Innovators also pointed out that 

child occupants are also more likely to 

be out-of-position compared to an adult, 

further contributing to uneven weight 

transfer. Auto Innovators argued that if 

the weight of a child in a booster seat 

is not transferred to the weight sensor, 

the proposed system could misclassify 

the seat as empty. If this 

misclassification occurs, coupled with 

the lack of a visual warning for an 

unfastened seat belt at an unoccupied 

seat, Auto Innovators argued there 

would be no visual warning for cases 

where an age-appropriate child is sitting 

in a booster seat and not wearing a belt. 

Relatedly, IEE commented that more 

advanced detection technologies (such 

as cameras or radar sensors) are not 

currently used in the context of a seat 

belt reminder function, and that these 

technologies would still have to prove 

their reliability and robustness for the 

occupant detection needs of a seat belt 

reminder system. IEE explained that 

while future developments may enable 

the support of seat belt reminder 

functionalities with these technologies, 

it is too early to consider such a 

potential innovation in a regulatory 

pass/fail scenario. 

Honda, HATCI, Auto Innovators, 

NADA, IEE, RVIA, Honda, and GM 

commented that specifying criteria 

matching a 6-year-old would exacerbate 

the problem of false positives. HATCI 

and IEE commented that behavioral 

alternatives to avoid false positives, 

such as moving cargo to the floor of the 

vehicle or buckling the belt before 

loading heavy cargo onto seats, may not 

always be feasible or reliable. Auto 

Innovators and Honda argued that the 

proposed criteria would potentially 

discourage manufacturers from 

implementing occupant detection 

systems due to the potential for false 

warnings. 

IEE similarly commented that if the 

agency were to adopt the 6-year-old 

criterion proposed in the NPRM, 

manufacturers would be disincentivized 

from implementing occupant detection 

in rear seats. IEE explained that because 

the proposed detection threshold is not 

technically feasible today within a 

regulatory pass/fail context, the 

threshold proposed in the NPRM would 

fail advanced rear seat belt reminder 

systems that have already entered the 

U.S. market and that offer a seat belt 

warning functionality that exceeds the 

proposed legal minimum. IEE stated 

that this requirement would force 

vehicle manufacturers to withdraw 

these advanced seat belt reminder 

systems from the market and downgrade 

the seat belt reminder systems features 

to the legal minimum (the positive-only 

compliance option). IEE argued that this 

result would be counterproductive from 

a safety perspective. 

IEE and Consumer Reports 

commented that manufacturers could 

voluntarily detect occupants smaller 

than the 5th percentile female. IEE 

argued that making such detection 

voluntary would provide flexibility for 

innovation. Consumer Reports 

recommended that NHTSA incorporate 

detection of dummies smaller than the 

5th percentile female into NCAP ratings 

for rear seat belt reminders, which 

would award manufacturers for going 

above and beyond the regulatory 

minimum and drive innovation. 

On the other hand, NSC and SRN 

suggested a 3-year-old child for the 

occupancy criterion. NSC commented 

that data from the National Digital Car 

Seat Check Form show that many 

children are not riding in the 

appropriate CRS based on their height 

and weight, so specifying criteria 

corresponding to a 3-year-old child 

would protect children. SRN similarly 

noted that the weight of a 3-year-old 

dummy, though average for a toddler, is 

also the weight of many older children 

in the lower growth chart percentiles. 

SRN argued that since nearly all schoolage children ride in seat belts or 

boosters (including these lighter-weight 


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93See, e.g., Norman J. Singer & Shambie Singer, 

2b Sutherland Statutory Construction section 46:5 

(7th ed.) (‘‘[E]ach part or section of a statute should 

be construed in connection with every other part or 

section to produce a harmonious whole. Thus, it is 

not proper to confine interpretation to the one 

section to be construed.’’); section 47:3 (explaining 

that while legislative titles cannot control a statute’s 

plain words they ‘‘may help resolve uncertainty’’ 

and ‘‘illuminat[e] statutory meaning’’). See also id. 

section 47:6 (‘‘Courts give effect to all the language 

of a purview as a harmonious whole, in light of the 

statute’s purpose, and regardless of sectional 

formatting, unless to do so is plainly contrary to 

legislative intent.’’). 

94MAP–21, Division C, Title I, ‘‘MOTOR 

VEHICLE AND HIGHWAY SAFETY 

IMPROVEMENT ACT OF 2012.’’ 95 49 U.S.C. 30111. 96Center for Disease Control Growth Charts for 

Children 2–20 years of age: Boys Stature-for-age and 

children, regardless of NHTSA bestpractice recommendations), families 

would benefit from warnings about the 

belt-use status of those children. SRN 

explained that this is especially true for 

warnings that a passenger has 

unbuckled during a ride, which 

younger, less mature children may be 

prone to do. SRN explained that, as 

proposed, a system with occupant 

detection would not recognize some of 

the youngest booster/belt users, may 

provide inadequate warnings to 

families, and may cause caregivers some 

frustration in interpreting status 

indicators. SRN also commented that in 

comments to the ANPRM, SRN had 

voiced the concern that LATCHinstalled car seats could trigger false 

alarms. SRN was less concerned that the 

proposed system will rise to the level of 

nuisance and is more concerned that 

false warnings will happen, such as 

when relatively heavy car seats are 

installed using LATCH. SRN argued that 

owners will need clear guidance in 

owner’s manuals on how to interpret 

warnings when traveling with children, 

and that these instructions should be 

included (or at least referenced) in the 

child passenger section of the manual. 

Consumer Reports, HATCI, and 

Freedman agreed with NHTSA that a 

CRS detection requirement was not 

necessary. Consumer Reports stated that 

consumers might be better served by 

incorporating CRS detection into a 

component of NCAP for rear seat belt 

reminder systems to help drive safety 

innovation. Freedman commented that 

the easiest and most effective solution 

for LATCH-installed CRS is to continue 

recommending the seat belt be fastened 

behind the CRS. 

Auto Innovators and GM 

recommended that NHTSA ensure a 

technology-neutral approach that 

includes consideration of compliance 

options that permit the use of cameraor vision-based sensors, or other 

technologies that may be adopted in lieu 

of weight-based sensors, as a means for 

determining occupant presence at a 

given designated seating position. 

Advocates and Public Citizen 

commented that the final rule should 

not preclude or discourage the use of 

existing state-of-the-art technology. 

Agency Response 

After considering the comments, 

NHTSA has decided to adopt the 

proposal to use (at the option of the 

manufacturer) either a anthropomorphic 

test device at least as large as a 49 CFR 

part 572, subpart N 6-year-old child 

dummy or a person, at the 

manufacturer’s option, that is at least 21 

kg in weight and 114 cm in height to 

define an occupied rear designated 

seating position for the purposes of 

testing the rear seat belt reminder 

system. These criteria represent a 50th 

percentile 6-year-old child, and only 

specify the low end of the occupancy 

criteria used for compliance testing. 

Therefore, when we refer to a 6-year-old 

as our occupancy criteria, this includes 

occupants or dummies that are larger. 

Before addressing the specific issues 

raised by the commenters, it is 

important to recognize that this final 

rule does not require or necessitate 

occupant detection. Moreover, we 

recognize that a manufacturer currently 

deploying reminder systems with 

occupant detection based on the 5th 

percentile female would likely need 

some time and effort to develop and 

implement new sensor solutions in the 

rear. Based on MY 2022 NCAP data, 

approximately 7 percent of vehicles sold 

in the U.S. are equipped with rear seat 

belt reminders using occupant 

detection. The commenters, however, 

did not provide specific information on 

what additional development would be 

necessary to meet the requirements 

when tested with a 6-year-old. 

Further, as explained above (Section 

VI.A.2.a.i) we have revised the proposed 

requirements to provide greater 

flexibility for systems without occupant 

detection. The proposal only included 

one compliance option (the positiveonly compliance option) without 

occupant detection. In response to the 

comments, the final rule would allow 

for additional warning systems without 

occupant detection (e.g., negative-only 

and full-status). Given this flexibility, 

manufacturers can simply use reminder 

systems without occupant detection if 

they believe they cannot deploy a 

reminder system using occupant 

detection that would comply with the 

requirements when tested with a 6-yearold. 

Given the above, NHTSA has 

concluded that it would fulfill the 

MAP–21 mandate, meet the need for 

safety, and be practicable and 

appropriate to require that an occupant 

detection system be capable of detecting 

at least a 6-year-old. There are several 

reasons for this decision. 

First, section 31503 of MAP–21 

directs NHTSA to initiate (and finalize, 

if the § 30111 criteria are met) a 

rulemaking proceeding ‘‘to provide a 

safety belt use warning system for 

designated seating positions in the rear 

seat.’’ Section 31503 itself does not refer 

to particular classes of occupants or 

identify a target population. ‘‘Subtitle 

E—Child Safety Standards’’, in which 

§ 31503 is located, however, contains 

four mandates related to child passenger 

safety: improving the protection seated 

in CRSs during side impact crashes; 

improving the ease of use for LATCH 

systems; providing seat belt reminders 

for rear seats; and researching the risk 

of hyper- or hypothermia to children or 

other unattended passengers in rear 

seating positions.93 94

In addition, the Safety Act gives 

NHTSA the discretionary authority to 

issue safety standards to address 

specific safety needs, provided that the 

standard is objective, practicable, and 

appropriate for the type(s) of vehicles to 

which it applies.95 NHTSA has 

concluded that requiring a rear seat belt 

warning system equipped with 

occupant detection be able to detect 

unbelted children smaller than the size 

represented by the 5th percentile female 

crash test dummy meets a safety need 

and is practicable and appropriate. 

Specifying occupant characteristics 

corresponding to a 5th percentile female 

would not address rear seat belt usage 

by children because the vast majority of 

children are smaller than the 5th 

percentile female test dummy. The 

population of children seated in the rear 

who should be restrained with a seat 

belt is comprised of children seated in 

a booster seat and children who have 

transitioned out of a booster seat to sit 

directly on the vehicle seat. As we 

explained in the NPRM, children 

typically begin sitting in a booster seat 

(transitioning out of a forward-facing 

CRS) around 4–7 years old (depending 

on the height and weight of the child 

and the respective limits of their 

forward-facing car seat). Children 

typically transition out of a booster seat 

between the ages of about eight and 

thirteen (again, exactly when depends 

on the child’s height and weight). The 

Hybrid III 5th percentile female crash 

test dummy weighs 108 lb (50 kg). This 

weight corresponds (approximately) to a 

50th percentile fourteen-year-old girl 

and a 50th percentile thirteen-and-ahalf-year-old boy.96 This means that if 


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Weight-for-age percentiles and Girls Stature-for-age 

and Weight-for-age percentiles, published in May 

2000 (modified in November 2000) and available at 

https://www.cdc.gov/growthcharts/data/ 

set1clinical/cj41c022.pdf and https://www.cdc.gov/ 

growthcharts/data/set1clinical/cj41c021.pdf, 

respectively. (last accessed September 10, 2024). 

97A booster seat augments the total weight on the 

rear seat. However, as we explained in the NPRM— 

and as we adopt in this final rule—we will not be 

testing with a booster seat because we are aware 

that children can be prematurely transitioned to a 

seat belt without the use of a booster, and we 

believe it is desirable to test the lower end of the 

possible weight range that encompasses children 

that could conceivably be restrained with a seat belt 

alone. We discuss the issue of booster seats in our 

discussion regarding feasibility later in this section. 

98Page 114. As another example, the owner’s 

manual for the MY 2024 Tesla Model Y states: ‘‘If 

all occupants are buckled up and the [seat belt] 

reminder stays on, . . . remove any heavy objects 

(such as a briefcase) from an unoccupied seat.’’ 

99NHTSA is not disclosing further details about 

this finding because this information is 

confidential. 

100The Advanced Air Bag rule was targeted at 

protecting all individuals from potential harm from 

air bags; specific requirements were included that 

were targeted at protecting children. See Section 

VI.A.2.a.1. 

NHTSA were to specify criteria 

matching the 5th percentile female, it 

would essentially be ignoring a large 

percentage of children ages 6–14, and 

likely some 15–18 year old children 

with weight lower than that of a 5th 

percentile female. That is, if NHTSA 

specified the 5th percentile female, the 

rear seat belt warning requirements 

would only be targeting older children, 

not younger children.97 This disparity 

strongly suggests that NHTSA should 

specify a smaller occupant for testing if 

doing so would be practicable. 

Although NHTSA has concluded that 

specifying occupant characteristics 

matching those of a 6-year-old child 

would meet a safety need and be fully 

consistent with MAP–21, MAP–21 

directs NHTSA to issue a final rule only 

if the rule would meet the criteria set 

out in § 30111 of the Safety Act. These 

criteria include that the rule be 

practicable. As noted earlier, the 

statutory criterion of practicability is 

multidimensional (see Section IV. 

Statutory Authority). After considering 

the comments, NHTSA agrees that most 

currently deployed rear seat belt 

warning systems utilizing occupant 

detection are not able (or designed) to 

reliably detect a 6-year-old occupant. 

NHTSA also agrees with the 

commenters who indicated that there 

are a number of challenges to rear-seat 

occupant detection, related both to false 

negatives and false positives. However, 

while many or most currently deployed 

rear occupant detection systems used 

for seat belt warnings may not comply 

with the requirements in the final rule, 

we believe that OEMs are capable of 

improving the technology and meeting 

these challenges. Further, NHTSA 

believes that selecting a 6-year-old child 

instead of the 5th percentile female 

appropriately balances benefits and 

costs. We explain this conclusion in 

more detail below. 

NHTSA believes that while current 

occupant detection systems might not 

reliably detect a 6-year-old child, or a 

booster seat, such a requirement is 

feasible. NHTSA acknowledges the 

commenters who argued that many or 

most rear occupant detection systems 

that are currently deployed may not be 

able to reliably detect a 6-year-old 

occupant, either seated directly on the 

seat or in a booster seat. NHTSA has not 

tested current systems to verify or refute 

this claim, so we have no firm basis on 

which to agree or disagree with these 

comments. NHTSA has, though, noted 

that some owner’s manuals inform 

consumers that if they place lightweight 

objects (such as a briefcase) on the rear 

seat, it may trigger the seat belt warning; 

this suggests that some rear seat belt 

occupant detection systems may be 

capable of detecting younger (and 

therefore lighter) occupants. For 

example, the owner’s manual for the 

MY 2024 Cadillac Escalade states that 

‘‘[t]he rear passenger seat belt reminder 

light and chime may come on if an 

object is put on the seat such as a 

briefcase, handbag, grocery bag, laptop, 

or other electronic device. To turn off 

the reminder light and/or chime, 

remove the object from the seat or 

buckle the seat belt.’’ 98 In most cases 

the weights of these listed items would 

be less than the weight of a 6-year-old. 

Furthermore, we understand (although 

again, have not been able to verify) that 

at least one manufacturer’s system may 

be able to detect a 6-year-old not in a 

booster.99

We also acknowledge that some rearseat occupant detection systems may 

not be able to reliably classify a young 

child seated in a booster seat as an 

occupant. We explained in the NPRM 

that children start using belts (with a 

booster seat) at about 6 years old, and 

typically transition out of a booster seat 

around 8 to 13 years old. We 

acknowledge, as IEE commented, that 

some rear detection systems may not 

simply classify objects/occupants based 

on weight, but may also base the 

classification on other information, such 

as the pressure profile, so that a child 

seated in a booster seat may not be 

classified as a human occupant, 

regardless of the child’s weight and 

height. We recognize that manufacturers 

would have to develop a solution to this 

issue. We also acknowledge other issues 

pointed out by the commenters that 

make accurate detection a challenge, 

such as out-of-position children. 

Nevertheless, we believe that it is 

feasible to develop this technology. We 

agree with IEE that more advanced 

technologies (such as radar sensors) are 

not yet proven. However, occupant 

detection technology similar to that 

used for advanced air bag testing in the 

front that is used to detect different 

sized dummies in different test 

scenarios,100 including 6-year-old 

dummies, could potentially be 

reprogrammed to address our 

occupancy criteria needs and this would 

also address the comments about not 

being able to detect children in boosters. 

Testing with a 6-year-old should also be 

compatible with the requirements in 

ECE R16 and Euro NCAP; if a system 

can recognize a 6-year-old occupant, it 

should also be able to recognize an 

occupant with the characteristics of the 

5th percentile female. Moreover, to give 

manufacturers flexibility, we have kept 

the requirements as technology-neutral 

as possible in order to facilitate 

innovation. We acknowledge that 

requiring an occupant detection system 

to meet the final requirements when 

tested with a dummy or human 

representing a 6-year-old could increase 

the cost of the system and may take 

some time to implement and test, but 

again, the final rule does not require 

occupant detection. We are also 

providing two years of lead time, so 

current occupant detection systems 

could be offered until then (See Section 

IX, Compliance Date). 

With respect to the comments on 

cargo (or pets) leading to false warnings 

based on the relatively low weight 

specification for the occupancy criteria, 

while this is a potential issue, we 

believe that it is mitigated in a variety 

of ways. First, potential consumer 

annoyance should be mitigated by the 

relatively short duration of the warning 

(60 sec) and the fact that it does not 

have an audible component. The weight 

of the types of objects typically placed 

on the rear seats (such as briefcases, 

water bottles, and groceries) would also 

likely be well under the weight of a 6- 

year-old (46.5 lb). 

There may also be technical solutions 

to mitigate false warnings. Several 

comments referred to complications 

with detection related to the weight of 

the occupant or object placed on the 

seat. However, occupant detection 

technology reliant solely on weightbased sensors may not necessarily be 

the only technology solution to meet the 

performance requirements in this final 


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101See www.nhtsa.gov/road-safety/child-safety 

(last accessed May 16, 2024). 

102For example, the owner’s manual for the MY 

2024 Subaru Forester advises the consumer that 

‘‘[t]he seatbelt warning system of the rear seats 

detects if any of the seats are occupied by a 

passenger. Installing a child restraint system in the 

rear seating area, using the LATCH anchors, may 

result in the activation of the passenger seatbelt 

warning light and chime. Fastening the rear seatbelt 

prior to installing the child restraint system will 

avoid activating the passenger seatbelt warning 

light and chime.’’ 

103See https://www.nhtsa.gov/crashworthiness/ 

child-safety-crashworthiness-research#:∼:

text=Since%20children%2012%2Dyears%2Dold,

booster%20seats%20and%20seat%20belts (last 

accessed May 16, 2024). 

rule. We also note that, based on the 

comments alone, it appears that there 

are presently issues with false alarms for 

current systems which are presumably 

based on detecting a 5th percentile 

female occupant. (However, no specific 

data were provided on the performance 

of these systems with relation to false 

warnings or how such false warnings 

have affected acceptance.) 

If technical solutions to mitigating 

any remaining consumer acceptance 

concerns are not readily available, 

NHTSA continues to believe the 

behavioral solutions we suggested in the 

NPRM (such as placing objects on the 

floor instead of the seat, or buckling the 

belt if cargo is placed on the seat) are 

viable. Although Honda and HATCI did 

not believe such behavioral solutions 

were viable, as noted earlier, at least 

some manufacturers are already 

providing such guidance in the owner’s 

manual. We acknowledge that there may 

be some trade-off in effectiveness if 

consumers frequently buckle the belt 

when cargo is placed on the seat or 

become accustomed to ignoring the 

warning. (We are not aware of any data 

or research on such trade-offs.) 

Nevertheless, we believe that this 

concern would not meaningfully affect 

the warning’s effectiveness, and that any 

lessening in effectiveness should be 

offset by the system being able to detect 

the full range of occupants that should 

be using a seat belt. 

With respect to interactions between 

the occupant detection system and 

CRSs, we agree with the commenters 

that the final rule should not require 

that the occupant detection system be 

able to detect a forward- or rear-facing 

CRS installed with LATCH. We agree 

with Freedman and Honda that the 

easiest and most effective solution to 

avoid false warnings for LATCHinstalled CRSs is to continue 

recommending the seat belt be fastened 

behind the CRS. We encourage this 

practice on our website 101 and some 

manufacturers are already providing 

consumers with this guidance.102

NHTSA also considered the relative 

costs and benefits of specifying a 6-yearold child as opposed to the 5th 

percentile female. In particular, we 

considered some commenters’ 

assertions that specifying the 6-year-old 

would discourage manufacturers from 

adopting systems with occupant 

detection or would force manufacturers 

to downgrade their systems to the 

positive-only option (which did not 

require occupant detection). We have 

concluded that specifying a 6-year-old 

as opposed to the 5th percentile female 

appropriately balances costs and 

benefits. There are several reasons for 

this conclusion. 

First, and most important, a system 

that does not monitor child occupants 

smaller than a 5th percentile female 

does not monitor the entire population 

of children who can and should be 

using seat belts. As we noted above, the 

height and weight of the 5th percentile 

female dummy correspond, 

approximately, to that of a 14-year-old. 

Because the 5th percentile female 

dummy would not represent most 

younger children, the system would not 

work accurately for these children. This 

is especially worrisome given that 

children 12 years old and younger 

represent more than half of the rear seat 

occupant population.103

Accordingly, specifying the 5th 

percentile female could result in 

unbelted child occupants in the rear not 

benefiting from the seat belt warning. 

For instance, if a negative-only system 

with occupant detection did not detect 

an unbelted child smaller than the 5th 

percentile female seated in a rear seat, 

the visual warning would not indicate 

an unbelted occupant at an occupied 

seat (e.g., for systems with a pictogram 

that indicates which seat are not in use, 

the pictogram would likely display 

something like a ‘‘grayed-out’’ seat to 

indicate that the system was registering 

a seat as unoccupied). In this scenario, 

the driver may not realize that the 

system was not detecting the child 

occupant and may think the child is 

buckled when they are not. This 

concern is not hypothetical. The 

owner’s manual for the MY 2024 Subaru 

Forester states that ‘‘[t]he driver must 

check that all the passengers have 

fastened their seatbelts properly since 

the seatbelt warning system may not 

detect passengers under the following 

circumstances.—When cushions or 

child restraint systems, etc., are used— 

When a child or small adult is sitting in 

the seat.’’ The fact that the system does 

not work for some classes of occupants 

could also lead the driver to be less 

likely to respond to accurate warnings. 

These shortcomings could also affect 

consumer acceptance of the system. 

Second, the concern about 

downgrading to a positive-only system 

is alleviated because we have modified 

the proposal so that the final rule does 

not dictate specific compliance options 

for the information conveyed by the 

visual warning; the finalized 

requirements for the visual warning 

allow all of the systems that would have 

been allowed under the proposed rule, 

as well as additional systems that would 

not have been allowed under the 

proposal. 

Third, a very small percentage of 

vehicles currently sold in the U.S. is 

equipped with rear-seat occupant 

detection. Based on the 2022 NCAP 

data, approximately seven percent of 

light vehicles have SBWS with occupant 

detection for the rear seats. Relatedly, 

rear systems with occupant detection 

are a relatively new feature in the U.S. 

vehicle market. So even if some 

manufacturers were to stop offering 

occupant detection, it would affect a 

relatively new feature on a small 

fraction of vehicles offered for sale in 

the U.S. and would not be a meaningful 

reduction in the choices presently 

offered to consumers. 

Fourth, this trade-off may or may not 

materialize. The trade-off would not 

occur if manufacturers develop and 

deploy rear-seat occupant detection 

systems capable of detecting a 6-yearold within the allotted lead time (two 

years). 

Fifth, the possibility that some 

manufacturers may choose to forgo 

occupant detection because the final 

rule specifies the 6-year-old does not 

lead us to conclude that it would be 

preferable to specify the 5th percentile 

female. We considered the relative 

benefits and costs of specifying each of 

these systems. 

The target population addressed by 

this rule will necessarily be larger if we 

specify the 6-year-old—and, 

importantly, this addition to the target 

population consists of children. Due to 

a lack of data, the FRIA was unable to 

establish how much more effective a 

rear seat belt reminder system with 

occupant detection would be relative to 

a seat belt reminder system without 

occupant detection. However, it is 

important to note that the baseline seat 

belt use rate for rear seat occupants ages 

6 to 10 years is already very high. As it 

is unlikely that the seat belt use rate 

would reach 100 percent, this leaves 

very little room for improvement. 

Accordingly, the children who will 

benefit from the rule if we specify the 

6-year-old is effectively children from 

about ages 11–18. This is still a larger 


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104The NPRM explained that while the main 

advantage is more informative warnings and that it 

can reduce false warnings for unoccupied seats, it 

can also (as pointed out by some commenters) 

result in false warnings. 105Because of data limitations, NHTSA was 

unable to break out this information for this age 

group specifically. NHTSA was only able to 

segment the analysis into occupants ages 6–10 and 

occupants 11 and older. 

106Paul Schroeder & Melanie Wilbur, Survey of 

Principal Drivers of Vehicles with a Rear Seat Belt 

Reminder System. Washington, DC: National 

Highway Traffic Safety Administration (2015). 

target population than if we specified 

the 5th percentile female. Targeting this 

population points towards greater 

benefits. 

On the other hand, if NHTSA 

specifies the 6-year-old, at least some 

manufacturers may offer fewer rear seat 

belt reminder systems with occupant 

detection. However, we are unable to 

estimate the overall impact of this 

potential reduction because of several 

unknowns: how many fewer systems 

with occupant detection will be offered; 

the difference in effectiveness between 

systems with occupant detection and 

systems without occupant detection; 104

and the seat belt use rates, injuries, or 

fatalities for children ages 11–18.105 We 

also believe that any short-term decrease 

in net benefits (if that should in fact 

materialize) is outweighed by what we 

anticipate to be the greater benefits in 

the medium-to-long term for children. 

Moreover, specifying the 6-year-old 

would result in seat belt reminder 

systems that are able to reliably inform 

the driver of unbelted children in the 

rear seat. While our regulatory analysis 

is not able to quantify these benefits to 

an especially vulnerable occupant 

population, we recognize the 

importance of these unquantified 

benefits. NHTSA therefore concludes 

that specifying the 6-year-old 

appropriately balances benefits and 

costs compared to specifying the 5th 

percentile female. 

v. Duration 

NHTSA proposed that the start-of-trip 

warning last for at least 60 seconds. We 

believed that 60 seconds would be 

sufficient to capture the driver’s 

attention and appropriately balanced 

effectiveness and acceptance. 

60 seconds is a shorter warning than 

we proposed for the front outboard 

seats. There were a couple of reasons for 

our tentative decision that a shorter 

warning is warranted for the rear seats. 

First, we did not propose to require 

occupant detection for the rear seat belt 

warning system; the positive-only 

compliance option would require that 

the driver be informed of which rear 

seat belts are fastened. This type of 

‘‘warning’’ functions more to provide 

information to the driver, rather than a 

true warning (because it will be 

providing information to the driver even 

if all rear occupants have fastened their 

seat belts), so we tentatively believed 

that it is not necessary to require that it 

be particularly long-lasting. Second, and 

related, even for the compliance options 

that would entail occupant detection, 

the complexities of occupant detection 

in the rear seats and the possibilities for 

false positives provide another reason 

for not requiring an extremely longlasting warning. Manufacturers would 

be free to provide a longer warning. 

This duration was consistent with 

ECE R16, Euro NCAP, and the IIHS 

protocol, each of which requires a visual 

warning at the start of the trip for the 

rear seat belts lasting at least 60 

seconds. It is also consistent with many 

of the rear seat belt warning systems 

currently deployed in the United States. 

In the NPRM we noted that, of the 

fifteen manufacturers that provide 

vehicle models with a rear seat belt 

warning system in the United States, 

eight appeared to provide systems with 

initial visual warnings that are active for 

at least 60 seconds. An additional three 

manufacturers appeared to provide 

visual warnings until the seat belt is 

fastened. 

Comments 

Auto Innovators, Freedman, Honda, 

HATCI, and Consumer Reports 

supported a 60-second minimum 

requirement. Auto Innovators and 

HATCI commented that this 

requirement would align with ECE R16. 

SRN requested a longer-duration 

warning requirement. It argued that the 

proposed warning would be only 

moderately effective (especially for 

occupants of rideshare vehicles) because 

it could be easily ignored. SRN also 

commented that caregivers, who may 

have children in car seats and boosters, 

may need more time to interpret the 

warning. SRN also suggested that a seat 

belt status indicator could be valuable 

as a constant readout on the dashboard, 

as warning lights are sometimes 

dismissed or ignored. 

Agency Response 

The final rule adopts the proposed 60- 

second minimum duration. We believe 

this requirement appropriately balances 

effectiveness and acceptance. A 2015 

survey of drivers of vehicles with 

RSBWSs found that 28 percent of GM 

drivers noticed an increase in rear seat 

belt usage, and 23 percent of Volvo 

drivers reported an increase in rear seat 

belt usage.106 The GM system used a 30- 

second visual warning at start-up and 

the Volvo system provided a short 

message at start-up, suggesting that a 60- 

second warning would be at least as 

effective. The 60-second minimum 

duration also harmonizes with ECE R16, 

Euro NCAP, and the IIHS protocol. 

A longer warning then 60 seconds 

could be annoying (in particular for 

systems without occupant detection that 

display unfastened belts). We also 

believe that 60 seconds is long enough 

to interpret the warning. This is what 

some current systems use, and we have 

no information to suggest that 

consumers have had difficulty 

interpreting the warning. This is a 

minimum performance requirement so 

manufacturers may voluntarily provide 

warnings lasting longer than 60 seconds. 

On the other hand, we are aware of 

vehicles that provide shorter warnings, 

so having a 60-second requirement will 

ensure a minimum level of performance. 

vi. Other Aspects 

NHTSA also received comments on 

other aspects of the proposed rear seat 

belt warning requirements. 

Comments 

Tesla requested that NHTSA clarify 

whether the ‘‘rear rows’’ reference 

includes all designated rear seating 

positions. Tesla also commented asking 

if the agency had a plan to also address 

integrated child seats that have seat belt 

reminder technology. Auto Innovators 

commented that the proposed 

S7.5(c)(1)(ii), requiring a visual and 

audible change of status warning, and 

S7.5(c)(2)(ii), prohibiting a visual 

warning that a seat belt is not in use for 

an unoccupied seat, are inconsistent 

and require clarification. 

Agency Response 

The final rule retains the reference to 

‘‘all rear designated seating positions.’’ 

The proposed regulatory text did not 

refer to ‘‘rows’’; it simply referred to 

‘‘rear designated seating positions.’’ 

Accordingly, it applies to all rear 

designated seating positions in 

applicable vehicles. 

It is not necessary that the rule 

specifically address integrated child 

seats. Integrated child seats are CRSs or 

booster seats that are built into the 

vehicle seat. A child seated in an 

integrated child seat is secured with 

either a seat belt or a harness. If the 

child is secured with a seat belt, then 

the seat belt warning should monitor 

belt use as with any seat belt. If the 

child is secured with a harness, the seat 

belt reminder would not be required for 

the harness, because children in an 

integrated seat with a harness are not 

part of the target population for this rule 


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414 Federal Register / Vol. 90, No. 2 / Friday, January 3, 2025 / Rules and Regulations 

107See https://www.volvocars.com/lb/support/ 

car/xc90/article/3212aabb4f810a77c0a

8015146e81cc9 (last accessed May 16, 2024). 

108Section 2.47. 109Section 8.4.3.3 (front seat belts) and section 

8.4.4.5 (rear seat belts). 

110These summaries simplify the requirements 

somewhat. They will be discussed in greater detail 

later in the preamble where relevant. 

111Section 3.4.1.5. 

112Section 3.4.1.5. 

113Section 3.4.1.5. 

114Section 3.4.3.1.1. 

115Section 3.4.1.6. 

116Section 3.4.3.2. 

117Section 3.4.1.6. The audio signal must resume 

when the speed goes above 25 km/h (15.5 mph) and 

no doors have been opened and the seat belt(s) 

remain unbuckled. In addition, the audible signal 

may instead meet the requirements for the front 

seating positions, if the vehicle is equipped with 

occupant detection. 

118Section 8.4.2.4.1. 

119Section 3.4.3.2.3. 

just as children in rear- and forwardfacing CRSs are not part of the target 

population. In addition, we were unable 

to identify any new vehicles with 

integrated child seats that use a harness. 

Integrated booster seats would not pose 

an issue for the seat belt warning 

system, and we are aware of only one 

vehicle manufacturer that offers 

integrated booster seats on some 

vehicles as an option.107 Regarding Auto 

Innovators comment, the final rule does 

not include the proposed requirement 

that the warning is not permitted to 

indicate a seat belt is not in use for an 

unoccupied seat because we do not 

believe this is necessary. 

b. Audio-Visual Change-of-Status 

Warning 

NHTSA proposed requiring an audiovisual warning when a rear seat belt is 

unbuckled during a trip. We proposed 

that an audio-visual warning must 

activate when the ignition switch is in 

the ‘‘on’’ or ‘‘start’’ position, the vehicle 

is in forward or reverse drive mode, and 

the status of the seat belt changes from 

in use to not in use, unless any rear door 

is open, in which case a change-ofstatus warning would not be required. 

The exception for an open rear door was 

intended to allow for passengers to exit 

the vehicle when the driver does not 

shift into park without activating the 

change-of-status warning. 

The audio-visual warning would have 

to last for at least 30 seconds or until the 

seat belt that triggered the warning is in 

use. We proposed that the audible signal 

may be ‘‘intermittent’’ (i.e., not 

continuous), which mirrors the 

longstanding requirements for the 

driver’s seat belt warning. If 

intermittent, we proposed that inactive 

periods longer than three seconds 

would not be counted toward the total 

minimum duration of the audible 

warning. Because the required 

minimum duration was relatively short, 

we did not propose additional audible 

signal characteristics, such as a duty 

cycle. (In contrast, we proposed 

additional signal characteristics for the 

front seat belt change-of-status warning 

because of the required longer duration 

for that warning. The final rule 

decisions on these aspects of the front 

seat warning are discussed in Section 

VI.B.3). 

ECE R16 similarly specifies an audiovisual change-of-status warning for rear 

seats. Specifically, if a fastened belt 

becomes unfastened when the vehicle is 

in ‘‘normal operation’’ (defined as 

forward motion at a speed greater than 

10 km/h (6.2 mph)),108 ECE R16 

specifies an audio-visual warning 

(second level) when certain distance, 

time, and/or speed threshold(s) (at the 

choice of the manufacturer) are 

exceeded.109 The additional thresholds 

are distance traveled (not to exceed 500 

meters), vehicle speed (not to exceed 25 

km/h (15.5 mph), and/or travel time (not 

to exceed 60 sec). This warning must 

last for at least 30 seconds unless the 

unfastened belt becomes fastened, the 

seat associated with the unfastened belt 

is no longer occupied, or the vehicle is 

no longer in normal operation.110 This 

warning may not be canceled by the 

driver. 

Euro NCAP also requires (to earn 

points) an audio-visual change-of-status 

warning at vehicle speeds of 25 km/h 

(15.5 mph) and above.111 If the change 

of status occurs below 25 km/h (15.5 

mph) and no doors are opened, the 

signal may be delayed until the vehicle 

has been in forward motion for 500 

meters or has reached a forward speed 

of 25 km/h (15.5 mph).112 A warning is 

not required if the system has occupant 

detection as long as all doors remain 

closed and the number of buckled 

positions remains the same, in order to 

minimize the number of false positives 

(e.g., children remaining in the vehicle 

but swapping seats in the rear while at 

a traffic light).113 The warning duration 

differs for the visual and audible 

warnings. With respect to the visual 

warning, if the system does not have 

occupant detection, the warning must 

last until the seat belt is fastened or 60 

seconds have elapsed.114 If the system 

does have occupant detection, the signal 

must remain on until the belt is 

fastened. The audible warning must last 

until the belt is fastened,115 30 seconds 

have elapsed,116 or the vehicle speed 

falls below 10 km/h (6.2 mph).117

ECE R16 118 and Euro NCAP 119 do not 

count periods in which the warning 

stops for longer than three seconds as 

part of the overall duration. 

The IIHS protocol also requires an 

audio-visual change-of-status warning 

lasting at least 30 seconds when the 

vehicle is in motion. The exact trigger 

depends on vehicle speed. When 

vehicle speed is between 10 and 40 km/ 

h (6.2 and 24.9 mph), the audio-visual 

warning must start within 30 seconds of 

continuous forward motion, and when 

the speed exceeds 40 km/h (24.9 mph), 

the audio-visual warning must begin 

within two seconds if the signal has not 

already begun. The warning can 

deactivate when the seat belt that 

triggered the warning is fastened; the 

vehicle is no longer in forward motion 

above 10 km/h (6.2 mph); or the seat or 

seats that triggered the warning are no 

longer occupied. Similar to Euro NCAP, 

the thresholds to trigger the primary 

audible signal and visual signal may be 

reset if any doors have been opened 

when the vehicle is not in motion. 

The proposal differed from ECE R16, 

Euro NCAP, and the IIHS protocol in 

some respects. The proposed 30-second 

duration was shorter than the 60-second 

duration for the visual signal specified 

in Euro NCAP, but consistent with the 

30-second duration for the audible 

signal. We also did not propose any 

speed, distance, or time triggers. And 

we did not propose the Euro NCAP 

allowance for not requiring a change-ofstatus warning when all doors remain 

closed and the number of buckled 

positions remains the same because it 

would require a delay in the activation 

of the change-of-status warning; also, 

these types of events are likely 

uncommon and require very little time 

to complete, so exposure to the warning 

would be very limited. 

Comments 

Consumer Reports agreed with the 

agency’s decision to require the changeof-status warning to include both 

audible and visual components. It also 

supported departing from ECE R16 and 

Euro NCAP and requiring a warning 

whether or not a vehicle is in motion 

because a stopped vehicle presents the 

best opportunity for the driver to ensure 

that the occupants are belted. 

On the other hand, Honda, Nissan, 

NADA, Tesla, Ford, Auto Innovators, 

and HATCI commented that reminder 

trigger conditions should harmonize 

with ECE R16 and/or Euro NCAP and be 

based on vehicle motion. Auto 

Innovators and Honda commented that 

the proposed requirements for providing 

an audible alert may result in 

widespread consumer acceptance 

issues. For example, Auto Innovators 

argued that establishing a trigger 


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120Section 3.4.1.5 (‘‘Where the system is able to 

track the number of buckled positions in the rear, 

no change of status signal (for the rear seats) is 

required as long as all doors remain closed, and the 

number of buckled positions remains the same. 

This is to minimize the number of false positives 

(ex: children remaining in the vehicle but swapping 

seats in the rear while at a traffic light.’’)). 

threshold based solely on the ignition 

being on, absent vehicle motion, will 

result in scenarios where an unbelted 

condition that may otherwise be viewed 

as reasonably acceptable would result in 

an audible alarm, including those where 

the vehicle is either stopped (and in 

drive) or slowing in anticipation of an 

upcoming stop (e.g., in a rideshare 

scenario or school drop-off). Auto 

Innovators recommended that NHTSA 

harmonize with ECE R16, which 

requires the audio-visual warning to be 

provided only when there is a change in 

seat belt status when the vehicle is 

traveling above 25 km/h (15.5 mph) or 

moving below 25 km/h (15.5 mph) for 

a period of 60 seconds. 

Auto Innovators further commented 

that the agency did not articulate why 

it has proposed that an audible alert 

occur when the vehicle is in reverse. 

Auto Innovators explained that such 

maneuvers are typically low-speed 

events, and that the agency has not 

provided clear justification for why an 

audible alert is needed in these 

scenarios. 

Honda commented that if NHTSA 

does not adopt a speed threshold, it 

could consider an alternative approach 

that would allow a single chime when 

the change of status occurs (assuming 

the vehicle is stationary) and then 

resume the full alarm when the vehicle 

begins moving. Honda commented this 

modification would minimize intrusive 

and annoying alarms, ensuring that the 

system still provides a warning but does 

not cause excessive consumer 

annoyance. 

We also received comments both in 

support of the proposed warning 

duration, as well as comments that 

recommended alternative durations. 

Auto Innovators, HATCI, and Honda 

support the proposed 30 second 

duration and harmonizing with ECE 

R16. Tesla encouraged harmonizing 

with either ECE R16 or Euro NCAP. 

Some commenters favored a longer 

minimum duration. Freedman argued 

that the audio warning should be the 

same as that for the driver seat 

(indefinite). Consumer Reports 

commented that the warning should last 

at least 60 seconds unless the belt is 

buckled, to be consistent with the startof-trip visual warning. Ms. Cross 

proposed requiring at least a 90 second 

minimum duration, pointing to, for 

example, consumer surveys showing 

that many consumers favor persistent 

warnings. 

Honda and Auto Innovators 

recommended that NHTSA allow the 

change-of-status warning to cease if a 

different belt is buckled (and the total 

number of buckled seats is restored) to 

allow the driver to recognize that a rear 

occupant has changed seats and 

refastened the belt. 

Tesla requested that NHTSA define 

the start time to measure the 30 seconds 

duration. Tesla further commented that 

if the warning continues after the seat 

belt is fastened, it may lead to a 

potential confusion on system 

functionality, which could lead to 

occupants ignoring future warnings. 

Agency Response 

In response to the comments, the final 

rule adds a provision to accommodate 

occupants switching seats. However, we 

are declining to adopt additional trigger 

conditions, such as a speed criterion. 

The final rule also includes the 

proposed 30-second duration. Our 

reasoning for these and other choices is 

detailed below. 

The final rule includes the proposed 

exception from activation when a rear 

door is opened, i.e., for a drop-off 

scenario: a change-of-status warning is 

not required if a rear passenger 

unbuckles and exits the vehicle. 

However, the final rule omits the 

additional proposed language that ‘‘the 

system may consider this situation as a 

new trip with respect to that seat belt 

and reset the warning system.’’ This 

language is vague and superfluous. The 

exception is based on the door opening, 

and there is no need to permit the 

system to ‘‘reset’’; manufacturers can 

program the system logic for the state of 

the system after a belt is unfastened and 

a door is opened as they deem 

appropriate, as long as the system 

complies with the finalized 

requirements. 

The final rule implements the 

recommendation from Auto Innovators 

and Honda to follow Euro NCAP and 

allow the change-of-status warning to 

deactivate if the system is able to 

recognize passenger(s) switching seats 

when all the doors are closed and the 

number of buckled positions remains 

the same. This change would limit the 

exposure to the warning if the 

occupant(s) changes seats and refastens 

the belt in another seat. Without this 

allowance, the warning would remain 

activated when all occupants were 

belted and would be unnecessarily 

annoying. This condition will also 

accommodate situations where a 

passenger buckles into a wrong buckle 

and corrects it. The additional 

regulatory text is based on Euro 

NCAP.120

However, we are declining to add the 

additional requested trigger conditions, 

or to simply require a single chime 

when a change of status occurs because, 

as we explained in the NPRM, seat belts 

provide a safety benefit even at lower 

speeds, and regardless of the direction 

of motion. We also believe a warning 

would be beneficial even if the vehicle 

is not moving. A driver may want to 

know if any rear seat occupants— 

especially children—have been 

unbuckled while the vehicle is 

temporarily stopped (e.g., at a traffic 

light) or slowed (e.g., in a parking lot), 

because the vehicle could soon be 

resuming travel. In addition, providing 

a warning when the vehicle is stationary 

would allow the driver to attend to the 

unbuckled passengers before having to 

focus attention on the driving task. We 

similarly believe that a warning would 

be useful before the vehicle has reached 

any distance or trip time threshold. The 

final rule also includes the reverse 

driving mode as a trigger as proposed. 

We believe this trigger is beneficial 

because it will require a warning before 

a vehicle begins driving on the road 

(e.g., before pulling out on to the road). 

We believe the benefits of having a 

warning activate in these circumstances 

outweighs the potential drawbacks 

identified by the commenters (for 

example, when the vehicle is stopped 

and the belt is unbuckled before a door 

is opened). In addition, we have 

eliminated the condition that the 

ignition switch be in the ‘‘on’’ or ‘‘start’’ 

position because it was redundant with 

the condition that the vehicle be in a 

forward or reverse drive mode. 

We do not believe that a visual 

warning alone, without an audible 

component, would be sufficient; a 

change of status is a serious event, due 

to the higher risk that comes with riding 

unbelted, and we believe this risk 

warrants a more effective audio-visual 

warning. In addition, the relatively short 

duration of the warning (30 seconds) 

should help minimize consumer 

annoyance in other scenarios that might 

result in an unbelted occupant in very 

low-risk scenarios. We therefore believe 

that consumers will accept the warning. 

NHTSA is also finalizing the proposal 

that the audio-visual change-of-status 

warning last at least 30 seconds (or until 

a rear door is opened). As we explained 

in the NPRM, this requirement is 

comparable to the change-of-status 

warnings on vehicles currently 

equipped with rear seat belt warnings. 


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121The change-of-status warning does not present 

the same concerns with false warnings as does the 

start-of-trip warning because the change-of-status 

warning is not triggered by occupancy. 

While we recognize that longer 

warnings may be more effective, we are 

not requiring a longer warning for the 

rear change-of-status warning. This 

requirement differs from the front seat, 

for which we are requiring a visual 

warning that lasts until the belt is rebuckled and a speed threshold for the 

indefinite audible warning. The main 

reason we are not requiring a longer rear 

change-of-status warning is to mitigate 

driver distraction. Because the majority 

of rear passengers are children, the 

driver would not necessarily be able to 

address the issue immediately and a 

longer warning could distract from the 

driving task.121 With respect to Ms. 

Cross’s comment, the survey on 

consumer acceptance for rear warnings 

does not support a specific duration, 

just that the majority found the feature 

acceptable, and the data on the majority 

of vehicles having at least a 90 second 

warning is for the front seat belt 

warning at the start of a trip, not a 

change-of-status warning, so they are 

not necessarily directly comparable. 

With respect to Tesla’s question about 

start time, the 30-second clock 

commences when the trigger conditions 

specified in the rule are met. The 

warning is permitted to stop if the 

occupant of the seat with the belt 

triggering the warning buckles within 30 

seconds. 

c. Electrical Connections/Removable 

Seats 

In the NPRM we explained that we 

had tentatively decided not to propose 

any requirements with respect to the 

electrical connections for folding, 

rotating, or stowable seats. Because 

these seats are not readily removable, 

the electrical connections should not be 

disturbed and could be accommodated 

with additional wiring. We did, 

however, propose two requirements 

related to the electrical connections for 

readily removable seats. 

First, we proposed that readily 

removable seats must either 

automatically connect the electrical 

connections when the seat is put in 

place or, if a manual connection is 

required, the connectors must be readily 

accessible. A system using a wireless 

connection could be classified as either 

automatic or manual, depending on 

whether the user needs to take any 

additional actions to establish the 

wireless connection when the seat is 

installed. We agreed with the 

commenters who recommended no 

prescriptive requirements to ensure 

manufacturers have flexibility in system 

design. 

Second, we proposed that vehicles 

using the negative-only compliance 

option provide a visual warning to the 

driver if a proper electrical connection 

has not been established for a readily 

removable seat because we were 

concerned that consumers could 

reinstall removable seats without 

making a proper electrical connection. 

We proposed requiring a visual warning 

for negative-only systems only because 

a faulty connection would result in the 

system not triggering any warning of an 

unbelted rear seat occupant. Moreover, 

for a negative-only system, the driver 

would otherwise have no reason to 

suspect that the system was 

malfunctioning, and so might mistake 

the lack of a warning as an indication 

that the rear seat occupant was belted. 

In the NPRM we explained why we 

believed that these issues were not 

present in full-status or positive-only 

warning systems. 

In the NPRM we stated our belief that 

both requirements would mainly affect 

minivans, which make up a small 

percentage of the fleet, but further 

explained that it might be possible to 

use the rear seat belt visual warning 

signal, with slight modifications (e.g., a 

different color) to comply. 

Comments 

Freedman, ASC, Honda, and 

Consumer reports commented that they 

agree that readily removable seats 

should not be exempt from the proposed 

requirements. 

ASC also commented on potential 

challenges in establishing reliable 

electrical connections, explaining that 

seat belt technology to support seat belt 

reminder systems in the field today is 

contained within an electrical switch 

inside the buckle. According to ASC, 

this functionality presents two 

challenges. First, since the removal and 

reattachment of the seat will result in 

disconnecting/reconnecting the buckle 

wiring to the vehicle wire harness, the 

reliability of this connection needs to be 

studied to ensure it is robust against 

malfunction considering its use case. 

(RVIA also raised this concern in its 

comment.) Second, a user’s handling of 

the electrical interface presents an 

opportunity for accidental damage. ASC 

recommended further study to 

determine the robustness of this 

connection in these systems. 

RVIA commented that motor homes 

are also often equipped with nonconventional, custom-made rear seating, 

so that developing wiring and sensors 

for the seat belt warning system that are 

not damaged in the conversion process 

from seat to bed would be challenging 

if not impossible. RVIA further 

commented that the NPRM does not 

consider convertible seats. 

IEE recommended that a visual 

warning be required for all systems, not 

just the negative-only system. 

Agency Response 

The final rule includes the proposed 

electrical connection requirements for 

readily removable seats. We agree with 

the commenters who supported 

including these requirements that doing 

so would provide important safety 

benefits by helping to ensure that proper 

electrical connections are made and the 

warning system operates correctly, and, 

in the case of negative-only systems, 

warns users that a proper connection 

has not been made. We agree with ASC 

that there is a foreseeable possibility 

that users can accidentally damage the 

system. This risk is why the final rule 

requires a warning that alerts the driver 

if a connection has not been properly 

made or if there is a malfunction for 

negative-only systems (where there is a 

risk of the driver not being aware of the 

issue). 

We acknowledge the potential 

challenges associated with electrical 

connections pointed out by some of the 

commenters, but we believe the 

requirements are feasible. NHTSA’s 

understanding is that removable rear 

seats are relatively rare, and typically 

only installed in the second row of 

passenger vans (a very small percentage 

of the fleet). In the vehicles in which 

they are present, it is likely that the 

seats are not frequently removed, which 

would suggest that the electrical 

connections would not be exposed to 

constant removal and re-installation that 

could increase the likelihood of damage. 

Moreover, the fact that the seat is 

removable does not necessarily mean 

that removing the seat means disturbing 

the electrical connection. NHTSA is 

aware of one minivan model with a rear 

seat belt reminder and a removable seat 

(MY 2024 Toyota Sienna Hybrid); in 

that vehicle, the seat belt anchors— 

which contain the wiring necessary for 

the rear reminder signal to function— 

remain in place when the seat is 

removed, obviating any need to reestablish any electrical connections 

when the seat is re-installed. 

Furthermore, the technology at issue 

here is not complex; re-installing the 

seats simply would require reestablishing a connection. If a seat is 

designed to be removable, it would not 

be unreasonable to expect that the seat, 

when re-installed, continues to have the 

same functionality it had before it was 


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122NHTSA did some limited market research of 

European models with removable rear seats. In one 

(MY 2023 Peugeot 5008) the seat belt anchors did 

not appear to be affected by the removal of the seat. 

In another (MY 2023 Ford Tourneo Connect), visual 

indicators where the seat locks in place were used 

to confirm proper installation, but not pertaining to 

electrical connections specifically. 

123FMVSS No. 208 S4.2.7. 

124 49 CFR 571.3(b) (definition of ‘‘designated 

seating position’’). 

125Section 8.4.4.2. 

126Section 3.4.1.1. 

127 Insurance Institute for Highway Safety. (April 

2024.) Seat Belt Reminder System Test and Rating 

Protocol, Version III, pg. 7. 

removed. The fact that removable seats 

are not exempted by ECE R16 or Euro 

NCAP strongly suggests that this 

requirement is not unreasonable.122

Accordingly, we do not believe more 

study is necessary to determine the 

robustness of the connection. Electrical 

connections may not be necessary for 

every removable seat and only a limited 

number of vehicles are equipped with 

removable rear seats. It is also unlikely 

that seats are removed and reinstalled 

frequently. Therefore, this issue does 

not appear to warrant further study. In 

addition, the requirement for a warning 

if there is a malfunction also addresses 

safety risks associated with potential 

damage over time. 

With respect to RVIA’s comment 

regarding seating specific to motor 

homes, such as dinette seating, it is 

unlikely the requirements apply to 

motor home convertible seats. Motor 

homes not greater than 10,000 lb GVWR 

are generally not required to have rear 

seat belts.123 And NHTSA’s regulations 

exempt motor home seating locations 

labeled in accordance with S4.4 of 

FMVSS No. 207 from being classified as 

‘‘designated seating positions,’’ so that 

the seat belt and seat belt reminder 

requirements do not apply to motor 

home seats so labeled.124

The final rule does not expand the 

connection warning requirements to 

systems beyond the negative-only 

system. As mentioned in the NPRM, we 

only think this issue would pose a 

serious risk for negative-only systems. 

d. Owner’s Manual Instructions 

NHTSA proposed that the owner’s 

manual (which includes information 

provided by the vehicle manufacturer to 

the consumer, whether in digital or 

printed form) describe the warning 

system’s features, including the 

location, format, and meaning of the 

visual warnings. We also proposed that 

the owner’s manual include instructions 

on how to make any manual electrical 

connections for readily removable seats. 

These proposed additions would require 

a revision to the approved collection of 

information in OMB No. 2127–0541. 

Comments 

We received comments both in 

support of and in opposition to the 

proposed owner’s manual instructions. 

ASC agreed with the proposal to 

include information regarding seat belt 

reminder systems in the owner’s manual 

instructions. NSC commented that the 

owner’s manual instructions should 

include instructions on how to make 

any manual electrical connections for 

readily removable seats, like child 

passenger safety seats. NSC urged 

NHTSA to consider standardizing 

generic nomenclature as well as 

standardizing warning and icon symbols 

to reduce driver confusion. SRN 

requested that instructions regarding 

false warnings, such as when relatively 

heavy car seats are installed using 

LATCH, be provided. 

Auto Innovators opposed any specific 

owner’s manual requirements, 

particularly if the required language is 

not relevant or applicable to all 

vehicles. Auto Innovators commented 

that the extent to which guidance may 

need to be included in the owner’s 

manual is a function of how the system 

is designed; if there are certain aspects 

of the system design that may require 

additional instruction, this information 

should be provided at the discretion of 

the manufacturer. 

Agency Response 

The final rule includes, without any 

substantive changes, the proposed 

owner’s manual requirements. We agree 

that these requirements will aid in 

public adoption of the warning systems 

and help to achieve their full safety 

potential. In addition, with increased 

system complexity, greater knowledge 

and understanding of the system is 

required. Including detailed information 

in the vehicle itself is not practical. 

The final rule to some extent 

standardizes nomenclature by defining 

some terms used in the regulation and 

by specifying requirements for the 

visual warning characteristics. However, 

we attempted to minimize such 

requirements to the extent possible to 

provide manufacturers with design 

flexibility. We agree with Auto 

Innovators not to require including 

specific information on how warning 

systems with occupant detection 

function when a CRS is installed with 

LATCH and guidance on how to avoid 

activating the warning (e.g., by fastening 

the seat belt). As Auto Innovators points 

out, the extent of the guidance needed 

to potentially limit false warnings 

depends on the type of system and its 

technology and should be left up to the 

discretion of the manufacturer. 

Manufacturers may include language in 

the child passenger section of their 

manuals for further guidance on 

potential false warnings that is specific 

to their system capabilities. 

e. Telltale Location 

The NPRM proposed that the visual 

warning signal be required to be visible 

to the driver only and not the rear 

passengers. 

Comments 

Auto Innovators supported the 

proposal to provide flexibility for 

manufacturers to specify the location of 

any necessary telltales related to rear 

row seat belt use, provided they are 

visible to the driver. On the other hand, 

Freedman commented it would be 

beneficial for passengers to see the seat 

belt status in those vehicles with 

multiple rows of rear seats, and 

indicated that this requirement could be 

accomplished with additional monitors 

in the passenger seating area. 

Agency Response 

The final rule adopts the proposed 

requirement that the visual signal needs 

to be visible only to the driver. 

Although we agree with Freedman that 

it could be beneficial for rear passengers 

to see the warning, we conclude that the 

increased cost, complexity, and redesign 

such a requirement would entail would 

not be justified. However, 

manufacturers would have the 

flexibility to place the visual warning 

where it could be seen by some or all 

rear seat occupants. In Section VI.C.7. 

we discuss the implications of the 

telltale location as it relates to 

automated vehicles. This requirement 

harmonizes with ECE R16,125 Euro 

NCAP,126 and IIHS,127 all of which 

require that the rear seat belt visual 

warning be visible only to the driver. 

3. Alternative Warning Signals 

In the NPRM, we noted that the 

ANPRM had sought comment on 

requiring or specifying as a compliance 

option a rear seat belt warning that 

differs from the type of audio-visual 

warning that is currently required for 

the driver’s seat belt, such as a haptic 

warning. Commenters to the ANPRM 

generally argued that an alternative 

warning is not necessary and that an 

audio-visual warning would be 

appropriate. 


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128There are some compliance options for certain 

trucks and MPVs that permit passive protection in 

lieu of seat belts at the front outboard seating 

positions. See FMVSS 208 S4.2.3 (compliance 

options for trucks and MPVs weighing between 

8,500–10,000 lb); S4.2.6 & S4.2.1.1 (compliance 

options for walk-in van-type trucks and vehicles 

designed to be sold exclusively to the U.S. Postal 

Service 8,500 lb and less). 

129 87 FR 18560 (Mar. 30, 2022). 

130Section 8.4.1.1. ECE R16 requires seat belt 

reminders in vehicle categories M (passenger 

vehicles) and N (vehicles carrying goods). Category 

M vehicles have a maximum mass of 5 tons 

(approximately 11,000 lb) and category N vehicles 

have a maximum mass of 12 tons (approximately 

26,500 lb). 

131 88 FR 61674, 61691 (Sept. 7, 2023). 

132 49 CFR 571.208, S14. 

Comments 

We received one comment on this 

issue. Auto Innovators agreed that an 

alternative warning is not necessary in 

addition to the audio-visual warnings 

proposed. However, Auto Innovators 

commented that manufacturers should 

not be prohibited from using alternate 

warnings (in addition to the required 

alerts) if they choose to do so. 

Agency Response 

We are moving forward with the 

originally proposed requirements for 

audio-visual warnings, while neither 

requiring nor prohibiting alternative 

warning signals. We are specifying 

minimum performance requirements to 

balance the effectiveness and 

acceptability of these systems. 

Manufacturers may go beyond our 

requirements, such as by providing a 

warning on the instrument panel that 

must be acknowledged by the driver 

before any other use of the instrument 

panel is permitted. Manufacturers 

interested in implementing 

supplementary alternative warnings 

signals should take steps to ensure that 

what is used will not cause unnecessary 

confusion or annoyance. 

B. Front Seat Belt Warning 

Requirements 

1. Applicability 

In the NPRM, NHTSA proposed to 

require an audio-visual seat belt 

warning for any front outboard seating 

positions in passenger cars, and all front 

outboard designated seating positions 

certified to a compliance option 

requiring seat belts in trucks, MPVs, and 

buses with a GVWR of 4,536 kg (10,000 

lb) or less.128 NHTSA also proposed not 

to extend the seat belt warning 

requirements to front center seats. 

Additionally, in the NPRM the agency 

noted that the 2022 automated driving 

system (ADS) final rule 129 also 

addresses situations where an ADSequipped vehicle without manual 

driving controls has one or no outboard 

seats in the front row (e.g., an ADSequipped vehicle with only two seats in 

the front row, one or both of which 

would be classified as inboard 

passenger seating positions under 49 

CFR 571.3) and requires seat belt 

warnings for certain inboard seats in 

such vehicles. We proposed that these 

front inboard passenger seats have the 

same seat belt warnings as front 

outboard seats. However, although the 

proposed regulatory text for passenger 

cars addressed this ADS-related 

applicability issue, the regulatory text 

for trucks, MPVs, and buses did not 

have conforming revisions. 

ECE R16 requires a warning for seats 

in the same row as the driver in 

passenger vehicles up to 5 tons (∼11,000 

lb) and vehicles used for carrying goods 

(e.g., pick-up trucks, vans, commercial 

trucks) up to 12 tons (∼26,000 lb).130

Euro NCAP awards points for warnings 

for all front row seating positions. 

Comments 

Several commenters, including 

Consumer Reports, Ms. Freeman, 

Honda, Tesla, Mothers Against Drunk 

Driving (MADD), and Ms. Tombrello 

commented in support of requiring an 

audio-visual seat belt warning for front 

outboard passenger seats. Consumer 

Reports commented that most 

manufacturers already implement 

audible warnings for front outboard 

passenger seats that last more than eight 

seconds, and they agreed with updating 

the requirements to reflect marketplace 

changes that have resulted in more 

substantial audible warnings. Ms. 

Tombrello emphasized the value in 

mandating this technology to cover the 

remaining vehicles that have not yet 

incorporated it. 

IEE commented that NHTSA should 

consider mandating a seat belt reminder 

warning for the front row seats of 

vehicles with a GVWR beyond 10,000 

lb. IEE indicated that such vehicles are 

included in ECE R16, and it would be 

a safety relevant gain to cover the whole 

vehicle fleet. They also noted that ECE 

R16 includes some exemptions, such as 

foldable seats in entry areas of coaches, 

that could also be incorporated. 

Ms. Tombrello, MADD, Advocates 

and Public Citizen, and IEE supported 

extending the requirements to the front 

center seating position. Ms. Tombrello 

noted the high percentage of center-seat 

fatalities that were unrestrained and 

stated that many children may be seated 

in the front center seat. IEE commented 

that even with a possibly still negative 

cost-benefit analysis, NHTSA should 

consider including the front center seat 

because the market share of vehicles 

with front center seats can be expected 

to increase as EVs no longer have a 

transmission tunnel. IEE also noted that 

because ECE R16 includes the front 

center seating position, established 

technical solutions are available. 

Agency Response 

We are finalizing the applicability of 

the front seat warning requirements as 

proposed in the NPRM, except for a 

correction to the regulatory text for 

certain ADS-equipped vehicles. NHTSA 

appreciates IEE’s concerns regarding the 

harmonization and safety benefits that 

could be gained by expanding this rule 

to cover vehicles with a GVWR over 

10,000 lb. However, the agency will not 

do so in this final rule because we lack 

information on implementation cost to 

support such a requirement for heavy 

vehicles. The Safety Act requires that 

FMVSS be practicable, which includes 

appropriately weighting the benefits and 

costs of a requirement while ensuring 

that the standard meets the need for 

motor vehicle safety. As we explained 

in the NPRM, long duration or 

indefinite audio-visual warnings are 

typically appropriate only for occupied 

seats due to the nuisance and 

desensitization effects that occur when 

warnings are activated for unoccupied 

seats.131 We also noted several factors 

that enabled us to conclude that no cost 

is associated with requiring front 

outboard passenger seat occupant 

detection technology in the light vehicle 

fleet (the vehicles to which this rule 

applies). Specifically, light vehicles are 

covered by the advanced air bag 

requirements in FMVSS No. 208, so 

occupant detection in the front outboard 

passenger seat is already widely 

deployed as part of the air bag system. 

Additionally, passenger seat occupant 

detection systems are often installed in 

the light vehicle fleet in part for use in 

voluntary seat belt warning systems. 

Based on compliance and consumer 

information submitted to NHTSA, the 

agency was, and still is, unaware of any 

vehicles to which the requirements will 

apply which do not already have 

occupant detection for the front 

outboard passenger seating position. 

However, we do not currently have 

such information regarding the heavy 

vehicle fleet and therefore cannot come 

to the same (or any) conclusion about 

the costs associated with 

implementation of a similar requirement 

for heavy vehicles, so we are not going 

to extend the requirements in this final 

rule. Heavy vehicles are not covered by 

the advanced air bag requirements in 

FMVSS No. 208 132 and we do not have 


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133 Due to lack of data, NHTSA was unable to 

establish seat belt use rates for front center seat 

passengers under the baseline. The analysis 

therefore used the use rates for front outboard 

passengers. 

134 In the NPRM, NHTSA mistakenly referred to 

these vehicles as ‘‘medium-sized buses.’’ This was 

incorrect. ‘‘Medium-sized buses’’ refers to buses 

with GVWRs between 10,000 lb and 26,000 lb. 

data indicating the market penetration 

of occupant detection systems for front 

outboard passengers in the heavy 

vehicle fleet in the United States. 

Without this or other information 

indicating the adoption of occupant 

detection technology, NHTSA is unable 

to determine whether additional 

occupant detection systems may need to 

be incorporated into vehicle designs to 

support a seat belt reminder system and 

the associated cost, and therefore at this 

time cannot determine that such a 

requirement would be practicable. 

Given the safety problem associated 

with a lack of seat belt use in light 

vehicles, and the availability and 

strength of data for systems in light 

vehicles, delaying this rule to obtain 

information for heavy vehicles would 

not be prudent. Instead, we are 

finalizing this rule to cover light 

vehicles and achieve those safety 

benefits quickly. In the future, as more 

data regarding heavy vehicles is 

available, we may choose to extend 

these requirements. However, we are 

not doing so in this final rule. 

Additionally, NHTSA is finalizing 

this rule without a requirement for front 

center seats. As we explained in the 

NPRM, a system for the front center seat 

without occupant detection would 

provide limited benefit because it would 

be only a visible and not an audible 

warning, the low occupancy of the front 

center seat, and the limited number of 

vehicles in the fleet with a front center 

seat. In addition, we estimated that 

requiring a system with occupant 

detection for the front center seats 

would not be cost effective.133 This is 

discussed further in Section VIII.B.3 as 

well as in the docketed FRIA. While EVs 

present fewer technical barriers to 

having a front center seat, we do not 

have data suggesting that manufacturers 

of EVs are incorporating front center 

seats at higher rates, or that if they did 

so, the requirement would become cost 

effective. 

Finally, NHTSA is correcting the 

regulatory text for trucks, MPVs, and 

buses to address the potential for ADSequipped vehicles that may have one or 

no outboard seats in the front row. We 

discuss other considerations related to 

ADS vehicles in Section VI.C.7. 

2. Driver’s Seat Belt Warning for Light 

Buses 

In the NPRM we proposed to require 

buses with a GVWR greater than 3,855 

kg (8,500 lb) and less than or equal to 

4,536 kg (10,000 lb), or with a GVWR 

less than or equal to 3,855 kg (8,500 lb) 

and an unloaded weight greater than 

2,495 kg (5,500 lb), to be equipped with 

a driver seat belt warning. This 

requirement would close a loophole in 

FMVSS No. 208.134

Comments 

Consumer Reports supported 

NHTSA’s efforts to close this regulatory 

gap. 

Agency Response 

NHTSA is finalizing this provision as 

proposed without change. 

3. Visual and Audible Warning Duration 

and Activation 

In the NPRM, we proposed two 

separate audio-visual warnings for the 

driver and front outboard passenger 

seats. First, we proposed an audiovisual ‘‘start-of-trip’’ warning that must 

activate when the ignition switch is 

placed in the ‘‘on’’ or ‘‘start’’ position if 

the seat is occupied and the seat belt is 

not in use. This warning would be 

required to continue until the seat belt 

that triggered the warning is in use. 

Second, we proposed an audio-visual 

change-of-status warning that would be 

required to activate when the ignition 

switch is in the ‘‘on’’ or ‘‘start’’ position, 

the vehicle is in forward or reverse drive 

mode, and the status of the seat belt 

changes from in use to not in use. We 

also proposed that if the change-ofstatus occurs and a front door on the 

same side of the vehicle as the belt 

triggering the warning is open, the 

system can consider that the start of a 

new trip. The warning would be 

required to continue until the seat belt 

that triggered the warning is in use. We 

also proposed that the audio-visual 

warning would otherwise not be 

permitted to activate. 

ECE R16 requires a first-level visual 

warning and a second level audio-visual 

warning. The first level visual warning 

is a start-of-trip warning that must 

activate for at least 30 seconds a front 

seat belt is not fastened and the ignition 

is activated. The second-level audiovisual warning must activate when a 

seat belt at an occupied seat is or 

becomes unfastened when the vehicle is 

in ‘‘normal operation’’ (defined as 

forward motion at a speed greater than 

10 km/h) and specific threshold criteria 

are met (distance traveled, speed, time). 

The second-level warning must remain 

activated for at least 30 seconds, unless 

the safety belt is fastened, the seat is no 

longer occupied, or the vehicle is no 

longer in ‘‘normal operation.’’ 

The Euro NCAP specifications are 

largely similar to those in ECE R16, with 

some differences. For example, Euro 

NCAP requires a longer-duration ‘‘Loud 

and Clear’’ audible warning (90 

seconds) when an additional speed, 

time or distance threshold is met. The 

audio-visual signal must also 

immediately deploy if a change of status 

to unbuckled occurs at speeds over 25 

km/h (15.5 mph). When the change of 

status occurs below 25 km/h and the 

doors are opened, the system may 

consider this a ‘‘new journey.’’ To 

prevent unnecessary signals, both ECE 

R16 and Euro NCAP require that the 

system be capable of detecting whether 

the front passenger seat is occupied. 

The IIHS ratings protocol for the 

initial signal specifies that if a seat belt 

at an occupied outboard front-row 

seating position is unfastened at ignition 

and the vehicle achieves continuous 

forward motion (at least 10 km/h (6.2 

mph)), the audible signal must begin 

within 30 seconds when the vehicle 

speed remains between 10 and 40 km/ 

h (6.2 and 24.9 mph) and within 2 

seconds once the vehicle speed exceeds 

40 km/h (24.9 mph), if not already 

active. For the change-of-status signal, 

IIHS specifies the following: If a 

fastened seat belt at an occupied 

outboard front-row seating position is 

unfastened when the vehicle’s forward 

motion is between 10 and 40 km/h (6.2 

and 24.9 mph), then the primary audible 

signal must begin within 30 seconds of 

continuous forward motion; if a seat belt 

at an occupied outboard front-row 

seating position is unfastened when the 

vehicle’s forward motion exceeds 40 

km/h (24.9 mph), then the primary 

audible signal must begin within 2 

seconds if it has not already begun. 

In the NPRM, NHTSA proposed to 

require that the audio-visual reminder 

last indefinitely until the belts are 

fastened (or refastened, in the case of a 

change-of-status scenario) at any 

occupied front outboard seating 

position. We proposed that this 

requirement be both upon start-up as 

well as in a change-of-status scenario. 

We based this proposal on five reasons 

that supported our belief that the 

proposal would be practicable, 

objective, and meet the need for motor 

vehicle safety. First, the existing 

requirements are significantly exceeded 

by the warnings provided in current 

vehicles. Second, we tentatively found 

(in agreement with IIHS) that the 

current audible signal duration upper 

limit of eight seconds is ineffective for 

increasing seat belt use. Third, we 

tentatively believed that contemporary 


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consumers would accept a longer 

warning. Fourth, the technology 

necessary to implement such an 

enhanced warning is already standard 

equipment on almost all light vehicles. 

Fifth, a longer duration would be 

consistent with seat belt warning 

durations required or encouraged in 

other markets and ratings programs. 

We also sought comment on other 

duration alternatives, including those 

specified in or by ECE R16, Euro NCAP, 

and the IIHS. ECE R16 requires a 30 

second visual warning when the front 

seat belts are not fastened and the 

ignition is activated as well as an audiovisual warning that must activate for at 

least 30 seconds if the seat belt remains 

unfastened and specific onset criteria 

are met (e.g., distance traveled, speed, 

etc.). The Euro NCAP assessment 

protocol requires a visual signal that 

remains active until the seat belt is 

fastened, and a two-stage audible signal; 

the initial audible signal must not 

exceed 30 seconds and the final audible 

signal must be at least 90 seconds. 

Under the IIHS ratings protocol, the 

primary audible reminder signal for the 

front outboard seats must be at least 90 

seconds in total duration to obtain an 

‘‘acceptable’’ or ‘‘good’’ rating. 

Comments 

Duration 

NSC, Consumer Reports, and Ms. 

Freeman supported the proposed 

indefinite warning. NSC and GM cited 

IIHS studies estimating that audible 

reminders lasting at least 90 seconds 

were significantly more effective for 

increasing seat belt use than an 

intermittent audible reminder and could 

save up to 1,489 lives annually. NSC 

also noted IIHS research that suggests 

that indefinite and 100 second constant 

reminders increased seat belt use by 30– 

34 percent over an intermittent 

reminder. Consumer Reports agreed 

with updating the requirements to 

reflect that the marketplace now accepts 

more substantial audible warnings. 

Auto Innovators, Mercedes, Honda, 

NADA, GM, Tesla, Nissan, and Rivian 

Automotive (Rivian) opposed the 

proposed indefinite reminder. 

Commenters cited consumer acceptance 

concerns, and some, such as Mercedes, 

Ford, and Auto Innovators, expressed 

concern that vehicle owners might seek 

to circumvent use of the system in 

various ways. Auto Innovators also 

commented that requiring a persistent 

audible warning may distract the driver 

from the driving task and other relevant 

safety warnings and may also result in 

desensitization. Honda noted that these 

concerns may lead to consumer 

backlash if the triggering conditions fail 

to accurately target risky situations 

when trips commence or when trips are 

actively occurring. 

Auto Innovators commented that the 

proposal is inconsistent with the 

agency’s assertions with respect to the 

rear seat where a 60-second visual 

warning would be effective. They 

argued that 60 seconds is sufficient to 

capture the driver’s attention and that a 

longer warning would have the 

potential to become distracting or a 

nuisance. 

Commenters suggested a variety of 

alternative warning durations. Auto 

Innovators, Mercedes, NADA, and 

Nissan encouraged NHTSA to align the 

final requirement with the ECE R16 

requirement of 30 seconds. 

Honda and General Motors both 

recommended adopting a 90-second 

continuous audio-visual warning 

because it would be the most effective 

and is sufficiently persistent to ensure 

that occupants buckle up. Honda also 

encouraged the agency to consider 

whether adopting a warning that is 

continuously active (i.e., 100 percent 

duty cycle) for a definite duration of 90 

seconds would be as effective as the 

proposal to require an indefinite 

warning with a minimum duty cycle of 

20 percent. Honda comments that it 

believes that a continuous 90-second 

chime is sufficiently persistent and 

might offer greater effectiveness 

compared to an indefinite warning that 

delivers only a 6- second chime 

followed by a 24-second pause between 

chimes. GM cited the IIHS research 

mentioned above and an internal 

research study with the Virginia Tech 

Transportation Institute that they stated 

showed that even a seat belt reminder 

chime lasting only approximately 34 

seconds could result in all vehicle 

occupants in the study buckling their 

seat belts. 

Tesla and Rivian suggested 

maintaining the current 4-second 

regulatory duration. Tesla noted that 

longer duration warnings may increase 

the risk of distraction if a sensor 

malfunctions as well as lead to defeat 

attempts. Rivian commented that, based 

on the proposed triggers, the proposed 

continuous audible warning would 

sound in EVs even if the occupant does 

not intend to initiate a trip but rather 

just sits in the vehicle. It explained that 

depressing the brake at ignition places 

the vehicle in ‘‘Go’’ power mode and 

provides access to the vehicle’s full 

feature set. As a result, a driver 

occupying the vehicle and depressing 

the brake, even without shifting the 

vehicle into Drive mode, would initiate 

the continuous chime. Rivian suggested 

that the current requirement resolves 

this concern, or alternatively, NHTSA 

could allow a manual reset or 

discontinue feature. 

Start-Up Warning Trigger 

NADA, Nissan, Auto Innovators, 

Ford, Mercedes, Rivian, Honda, and 

HATCI specifically disagreed with the 

proposed ignition trigger for the 

indefinite warning and argued that it 

would result in consumer annoyance. 

Some commenters, such as Auto 

Innovators, HATCI, and NADA, 

suggested that the agency should more 

closely align with the trigger 

requirements of ECE R16, which 

requires a first level visual warning on 

start-up but does not require an audible 

alert to be provided until the vehicle 

travels 500 m, the vehicle speed exceeds 

25 km/h (15.5 mph), or the duration 

time (engine running, propulsion 

system activated, etc.) is more than 60 

seconds (second level warning). Nissan, 

Ford, and Honda urged NHTSA to 

contemplate harmonization with Euro 

NCAP and ECE R16 by including a 

minimum speed criterion for the trigger. 

Mercedes made a similar comment 

and argued that harmonization would 

allow for new seat belt reminder 

technology/designs to be implemented 

faster in the U.S. market. It also 

commented that it would support 

implementing the approach taken in 

IIHS’s protocol, which requires an 

audible warning to begin after driving 

for 30 seconds while exceeding 10 km/ 

h (6.2 mph) or within 2 seconds while 

exceeding 40 km/h (24.9 mph). Rivian 

also suggested use of the 10 km/h (6.2 

mph) IIHS threshold for the indefinite 

audible alert because it largely mitigates 

low speed crash concerns. Rivian also 

noted that this requirement would 

resolve concerns with activating the 

reminder during activation of Auto 

Hold, which applies the brakes when 

the vehicle is stopped even though the 

brake pedal is released. Ford supported 

using a visual warning when the vehicle 

is stationary because it offers the best 

balance of providing an important 

reminder before the start of a trip 

without the potential annoyance of a 

persistent audio warning, especially in 

use cases where an audio warning is not 

warranted. 

Several commenters, including 

Nissan, Ford, Auto Innovators, and 

Honda, had concerns regarding the 

proposed triggering conditions when it 

comes to consumer acceptance. Honda 

commented that the start-of-trip audiovisual warning should be triggered by 

vehicle motion (or, alternatively, by the 

vehicle being shifted into drive or 

reverse), not by the vehicle’s ignition 


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being turned on. Honda referred to 

consumer research suggesting 

desensitization regarding the intended 

purpose of the existing start-up alarm, 

which it argued might worsen under the 

proposed approach. Honda commented 

that most individuals do not 

comprehend why their car chimes at 

start-up and that consumers also often 

incorrectly identify this chime as being 

merely a normal start-up sound. Honda 

argued that an alarm should sound only 

when genuine need for the alarm exists. 

Honda also requested a clarification, 

if NHTSA were to retain the status of 

the ignition switch as a trigger. It 

pointed out that as proposed, the startof-trip warning ‘‘must activate when the 

ignition switch is placed in the ‘on’ or 

‘start’ position’’ (emphasis Honda’s). 

Relatedly, the proposed trigger for the 

change-of-status warning was tied to the 

vehicle being in forward or reverse gear. 

Honda pointed to a scenario where the 

driver buckles after turning on the 

ignition, and then unbuckles while the 

vehicle is still in park. In such a case, 

a warning would not be required (either 

start-of-trip or change-of-status). 

Accordingly, Honda suggested 

modifying the logic of the start-of-trip 

and/or change-of-status warning to 

require a warning in this situation. 

A number of commenters, such as 

Ford, HATCI, and Mercedes, noted 

specific consumer acceptance concerns 

with an ignition trigger in circumstances 

where a vehicle has been started but a 

trip has not begun or is not going to 

occur or when a vehicle is going to be 

travelling at low speeds. Commenters 

described situations including: when 

idling, waiting for passenger(s), 

warming up or cooling down a vehicle 

prior to a trip (Honda), waiting out 

inclement weather inside a vehicle, 

sitting in a stationary vehicle listening 

to audio (Honda), and, in the case of 

EVs, keeping the vehicle ‘‘ignition’’ on 

for extended periods while charging to 

allow use of air conditioning (Mercedes 

and Honda). 

Honda also commented that the 

proposed trigger is excessively stringent 

to meet the safety need and asked that 

the agency reevaluate the trigger 

mechanism to ensure it aligns with safe 

consumer expectations and behavior. 

Auto Innovators commented similarly, 

noting that the proposed approach does 

not meet the need for safety. Auto 

Innovators noted customer complaints 

regarding overly aggressive start-of-trip 

warnings that begin on start-up, before 

the driver even has the opportunity to 

put the belt on. Honda argued that crash 

data illustrate that crashes at sufficiently 

low speeds are not likely to lead to 

injury, and pointed to data indicating 

that occupants are highly unlikely to 

sustain injuries in crashes occurring 

below 10 mph. Honda also argued that 

speeds below 15 mph are typically not 

associated with regular roadway 

driving. The lowest posted speed limits 

on residential or urban roadways in the 

U.S. are typically set at 25 mph. Speed 

limits of 15 mph are more common in 

non-roadway settings like residential 

neighborhoods or parking lots. 

Some commenters suggested other 

alternatives beyond incorporation of a 

speed-based trigger. For example, 

HATCI and Honda suggested a trigger in 

which the audible warning begins when 

the transmission is placed into a 

forward or reverse gear. HATCI 

commented that this trigger would 

resolve some concerns with a stationary 

vehicle pre-trip or during pick-up and 

drop-off and for EVs. Auto Innovators 

posited a short visual warning as an 

alternative to an ECE R16 

harmonization. It noted that this 

approach would be consistent with the 

IIHS requirements for front-row seating 

positions, which also predicate second 

level audible alerts based on forward 

motion of the vehicle. Additionally, 

Auto Innovators argued that for the front 

outboard passenger seat, the triggering 

conditions should provide for a delay 

before a visual warning is required. 

Auto Innovators argued that this delay 

would be consistent with the proposal 

to allow for a similar delay for rear row 

occupants. It expected that this delay 

would address challenges in detecting 

seat occupancy instantaneously upon 

ignition. 

Change-of-Status Warning Trigger 

With regard to the change-of-status 

warning, commenters generally 

supported a requirement but several, 

including Mercedes, NADA, Honda, and 

Tesla, commented that the trigger for the 

change-of-status warning should 

include a minimum vehicle speed. 

Mercedes and NADA recommended 

NHTSA harmonize with the ECE R16 on 

this issue and require only a visual 

warning if the vehicle is stopped or 

travelling at slow speeds and 

incorporate an audio warning if the 

vehicle is travelling at speeds of 25 km/ 

h (15.5 mph) or greater. Nissan 

emphasized that when the trigger for 

audio warnings is solely based on gear 

selection, and these warnings are 

activated even when the vehicle is 

stationary, it has the potential to be 

irritating for the occupants, especially in 

situations such as being stuck in heavy 

traffic or waiting in drop-off lines. 

Honda commented that using vehicle 

speed would be more aligned with 

safety needs, and that triggering the 

warning any time the vehicle is in the 

drive mode would result in unnecessary 

alarms for individuals who are 

otherwise consistent belt users. Honda 

commented that this trigger would 

reduce acceptance of the system among 

regular belt users and desensitize 

consumers to the alarm. Honda also 

suggested adding seat occupancy as one 

of the activation criteria for the changeof-status warning to address use cases 

where an occupant buckles a seat belt 

for another seat that is unoccupied, and 

then unbuckles it. 

Nissan and HATCI emphasized 

consumer acceptance concerns with the 

proposed change of-status warning, in 

particular regarding drop-off. HATCI 

noted that the ECE R16 triggers are 

particularly useful for addressing these 

scenarios. It explained that in these 

drop-off scenarios, the proposed audible 

alert would sound until the passenger 

opens the door, which could be 

considered a nuisance to the occupants. 

Ford also noted that its vehicles tend to 

experience frequent ingress/egress 

scenarios (e.g., work use of farmers, 

ranchers or construction workers) where 

a persistent warning is not warranted. 

Honda suggested that if the agency 

retains the drive mode trigger for the 

change-of-status warning, an alternative 

could be to use a single chime when the 

vehicle speed is below a certain 

threshold at the time of unbuckling that 

becomes a persistent reminder of 

indefinite duration once the vehicle 

resumes motion (if the door remains 

closed). Honda argued that if NHTSA 

believes that a notification is needed, 

the single-chime approach would 

adequately notify the occupants in a 

non-intrusive manner. 

Mr. Gaal suggested that once a driver 

or front outboard seat passenger has 

unbuckled their seat belt during a trip, 

a visual change-of-status warning 

should immediately appear along with a 

singular audible beep, followed by a 

two-minute gap allowed before the 

indefinite audible component of the 

change-of-status warning occurs again. 

In the NPRM, the agency sought 

comment on the possibility of allowing 

deactivation of the audio-visual system 

and the situations under which it would 

be warranted. While comments on this 

topic are discussed more broadly in 

Section VI.C.6, we note here that a few 

commenters, such as Rivian, suggested 

a manual reset or discontinue feature as 

an alternative to a speed-based trigger. 

Honda, however, commented that if 

deactivation requires a complicated 

procedure, it is impractical to deactivate 

nuisance warnings for short trips and 

therefore this approach does not 

effectively mitigate driver annoyance, 


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135The final rule also applies to any inboard 

designated seating position for which a seat belt 

warning is required in S4.1.5.6 (which concerns 

inboard designated seating positions in passenger 

cars without manually operated driving controls). 

136 ‘‘The effects of persistent audible seat belt 

reminders and a speed-limiting interlock on the seat 

belt use of drivers who do not always use a seat 

belt,’’ April 2019, David G. Kidd Insurance Institute 

for Highway Safety, Jeremiah Singer Westat, Inc. 

especially in comparison to alternative 

triggers, like vehicle motion. Honda 

noted that the use of a motion-based 

trigger would eliminate the need for 

deactivation. 

Tesla requested clarification on the 

definition of ‘‘during the trip.’’ Tesla 

also asked how the front change-ofstatus warning is envisioned to be 

applied to vehicles in automated mode 

or full automation. 

Auto Innovators commented that 

NHTSA proposed unnecessary 

restrictions on when an audio-visual 

warning for a front outboard seat belt 

warning system is permitted to activate 

and requested that they be removed. It 

argued that there may be other 

circumstances, including those 

currently unforeseen by the agency, 

where a manufacturer may seek to 

provide a similar audio-visual warning. 

It also stated that it is unclear whether 

these restrictions prevent 

standardization of the audible alert used 

for both front and rear rows. 

AVIA observed, with regard to 

vehicles with automated driving 

systems, that the NPRM proposed that 

the front outboard seats be allowed to 

suppress and reset the change-of-status 

warning only when the front door being 

opened is on the same side of the 

vehicle as the seat belt triggering the 

warning. In contrast, the NPRM 

proposed that the rear seat belt warning 

system may suppress and reset the 

change-of-status warning when any rear 

door is opened. AVIA commented that 

while this distinction makes sense for a 

conventional vehicle, some vehicles 

with automated driving systems may 

have interior configurations that allow 

for a front outboard occupant to exit 

through a door that is not adjacent to 

their seat. Further, AVIA indicated that 

autonomous ride hailing manufacturers 

or operators may implement safety 

measures that only permit the door(s) on 

a particular side to be opened to 

encourage safer egress, even though the 

door(s) may not be adjacent to the 

occupant’s seat. AVIA noted that this 

scenario could lead to a seat belt 

change-of-status warning remaining 

active indefinitely after a front row 

occupant exits the vehicle. AVIA 

suggested the language of the change-ofstatus warnings (both front and rear) be 

updated to allow the change-of-status 

warning to be reset when any door 

designed to provide egress for the seat 

is opened. 

Agency Response 

After considering the comments, 

NHTSA has decided to modify the 

proposed front seat belt warning 

requirements. The final rule requires a 

visual warning whenever a driver or 

front outboard occupant is unbelted, 

and a two-phase audible warning.135

The first-phase audible warning is 

required to activate whenever the 

ignition switch is placed in the ‘‘on’’ or 

‘‘start’’ position (or upon manual 

activation of the propulsion system, but 

prior to the vehicle being placed in 

‘‘possible active driving mode’’ as 

defined by FMVSS No. 305), the seat is 

occupied, and the seat belt is not in use. 

The first-phase audible warning must 

continue for 30 seconds, until the seat 

belt that triggered the warning is in use, 

until the seat is no longer occupied, or 

until the second-phase warning 

activates, whichever comes first. 

The second-phase audible warning 

must activate and remain active when 

the vehicle speed is equal to or greater 

than 10 km/h (6.2 mph), the seat is 

occupied, and the seat belt is not in use. 

Under this approach, there is a startof-trip audio-visual warning, with the 

visual warning lasting until the driver 

and any front outboard passenger have 

fastened their belts, and the audible 

component lasting at least 30 seconds 

(regardless of vehicle speed) and 

remaining activated whenever the 

vehicle speed is 10 km/h or more. Thus, 

if the vehicle is on but not traveling at 

least 10 km/h (6.2 mph), the audible 

warning would end after 30 seconds, 

but would either continue or reactivate 

should the vehicle speed reach 10 km/ 

h or more. Similarly, the final rule 

requires an audio-visual change-ofstatus warning, with the visual warning 

required to activate and remain 

activated as long as the occupant 

remains unbuckled, and the audible 

component required to activate and 

remain activated whenever the vehicle 

is traveling at least 10 km/h. 

We are making these accommodations 

to reduce the potential that frequent belt 

users will interact with the audible 

warning. Additionally, as explained 

later in Section VI.C.5 and in the NPRM, 

we are specifying a level of audible 

characteristics, i.e., 30 second warning 

cycle, 0.5 Hz chime frequency, and a 20 

percent duty cycle, which we believe 

will allow manufacturers to optimize for 

acceptability while maintaining 

effectiveness. 

This brief summary only gives a highlevel overview of the requirements; the 

final rule contains additional 

specifications and nuances. These, as 

well as a response to the comments, are 

covered in detail below. First, we 

discuss the audible warning; then we 

discuss the visual warning. 

Audible Warning Duration 

NHTSA has chosen to finalize the 

indefinite warning (subject to certain 

triggers and conditions) because NHTSA 

has concluded that it strikes an 

appropriate balance between 

effectiveness and annoyance and meets 

the need for safety. 

As NHTSA explained in the NPRM 

and PRIA, and explains in the FRIA, 

over the years there have been a number 

of studies of reminder effectiveness by 

NHTSA and others. The results of these 

studies have been consistent though 

somewhat fragmentary. In general, 

longer warnings are more effective than 

shorter warnings, and audio-visual 

warnings are more effective than visual 

warnings alone. Overall, these studies 

provide evidence that the relative 

annoyance (e.g., longer duration, more 

frequent cycle) of a warning increases 

the effectiveness. The studies also 

suggest that annoyance and 

effectiveness are inversely related to 

acceptance, although not necessarily in 

the same way. Therefore, there is the 

potential to optimize systems so as to 

increase effectiveness and also enhance 

acceptance. However, NHTSA’s 

research also found that the evidence to 

date was not sufficient to clearly 

identify which specific signal 

characteristics were optimal. 

The proposal explained that in 

developing our estimate of the 

effectiveness of a front seat belt 

reminder with an indefinite duration, 

we used the results of a study 

conducted by the Insurance Institute for 

Highway Safety (IIHS) by Kidd et al. 

(2019).136 We explained that the study 

found that, relative to a short 

intermittent reminder, an audio-visual 

seat belt warning with a 100-second 

audible component increased seat belt 

use by 30 percent, and an audio-visual 

seat belt warning with an indefinite 

audible component increased belt use 

by 34 percent. In the NPRM, we 

explained that there were several 

limitations in this study, the main one 

being that the number of study 

participants was small, and, 

consequently, there was limited 

statistical power when comparing the 

change in rate of belt use between the 

different vehicle technology conditions. 

We noted that the study further 

discusses this and other limitations, 

such as how the demographics of the 


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137 Id. at pg. 16. 

138The study does not report how often these 

excluded participants circumvented the warning. 

Accordingly, this exclusion could lead the 

effectiveness estimate to be lower than it actually 

was. And to the extent that the rate of 

circumvention for the excluded BMW and Subaru 

participants differed, that could also affect the 

relative effectiveness of the indefinite and 100- 

second warnings. 

139This was an enhanced reminder with three 

cycles that occurred at ignition, 105 seconds after 

ignition, and 360 seconds after ignition. Each cycle 

was 20 seconds in duration. 

140 Kidd, D.G. (2012). Response of part-time belt 

users to enhanced seat belt reminder systems of 

different duty cycles and duration. Transportation 

Research Part F, 15, 525–534. 

141N. Lerner et al. (2007). Acceptability and 

Potential Effectiveness of Enhanced Seat Belt 

Reminder System Features. (Report No. DOT HS 

810 848). National Highway Traffic Safety 

Administration. 

142 Kidd, D.G. (2012). Response of part-time belt 

users to enhanced seat belt reminder systems of 

different duty cycles and duration. Transportation 

Research Part F, 15, 525–534. 

143The Kidd study excluded from participation 

individuals who reported never using a seat belt 

from participating in the study. As we explain in 

Section VIII, Overview of Benefits and Costs and 

the FRIA, our benefits estimates conservatively 

Continued 

study sample differs from part-time belt 

users nationwide. 

Another limitation in the study is that 

the confidence intervals for the reported 

estimates are large. The 34 percent 

effectiveness estimate for the indefinite 

reminder had a 95 percent confidence 

interval of (12.7, 59.9), and the 30 

percent effectiveness estimate for the 

100-second reminder had a 95 percent 

confidence interval of (10.9, 52.4.). Not 

only are the confidence intervals large, 

they also substantially overlap. 

We also note that the Kidd study 

further adjusted these effectiveness 

estimates to account for potential 

circumvention by study participants 

(e.g., buckling the seat belt behind the 

driver’s back). Four of the seventeen 

study participants assigned to the 

vehicle with the 100 second reminder 

and three of the sixteen participants 

assigned to the vehicle with the 

indefinite reminder circumvented the 

warning. Accordingly, ‘‘due to concern 

that the rate of seat belt use for 

participants who circumvented the 

vehicle technologies could bias the 

comparisons being made,’’ 137 the study 

authors repeated the analysis, except 

this time excluding those individuals 

who circumvented the warning. With 

that adjustment, the indefinite reminder 

increased seat belt use by 23 percent (95 

percent CI [6.5, 42.6]) and the 100 

second reminder increased seat belt use 

by 25 percent (95 percent C I [8.2, 

44.3]).138

In addition to these limitations in the 

Kidd study, the estimation of the 

effectiveness in the regulatory analysis 

has several other limitations or 

assumptions. These are discussed in 

detail in the FRIA. Thus, while the 

research is clear that longer durations 

are generally more effective than shorter 

durations, there is no conclusive 

evidence regarding what duration will 

maximize effectiveness (recognizing, of 

course, that duration is not the only 

warning characteristic and that other 

attributes, such as duty cycle, also affect 

effectiveness as well as annoyance). 

Nevertheless, the evidence is such 

that we are able to easily reject some of 

the specific suggestions from 

commenters for shorter warning 

durations. The 4-second and 30-second 

warnings suggested by some 

commenters are well below the typical 

duration for an audible warning in 

current vehicles. Further, a 4- or 30- 

second reminder is shorter and less 

persistent than the intermittent Chevy 

Cruise reminder 139 included in the 

Kidd study, compared to which both the 

100-second and indefinite audible 

warnings were significantly more 

effective. We are similarly unable to 

agree with General Motors, which 

referred to internal research showing 

that an audible warning lasting 34 

seconds would be sufficient. (In 

addition, NHTSA has not seen the 

underlying research or data.) 

The available evidence also does not 

lead us to conclude with confidence 

that, as asserted by Honda and General 

Motors, a 90-second continuous 

warning would be most effective. As we 

explained earlier, the Kidd study, while 

informative, still leaves uncertainty 

about whether a 90-second or indefinite 

warning would be most effective. We 

are also unaware of any study, as 

suggested by Honda, comparing a 90- 

second continuous warning to an 

indefinite 20 percent duty cycle 

warning. However, a study of indefinite 

warnings with 100 percent and 20 

percent duty cycles found no difference 

in their relative effectiveness, which 

suggests that a 90-second continuous 

warning would not necessarily be more 

effective than a 20 percent duty cycle 

indefinite warning.140 Similarly, we are 

not aware of—and the commenters did 

not present—any persuasive evidence 

that an audible warning lasting greater 

than 90 seconds and less than indefinite 

would be at least as effective as an 

indefinite warning. 

In light of the available evidence, 

NHTSA has therefore concluded that 

requiring an audible warning that lasts 

until all front outboard occupants are 

belted best and appropriately balances 

effectiveness and annoyance, and will 

help to ensure that as many as possible 

occupants take advantage of one of the 

most safety-enhancing technologies, the 

seat belt. As we explained above, there 

is uncertainty about the most effective 

duration and the magnitude of the 

effectiveness. The commenters did not 

provide any persuasive evidence or data 

that a shorter audible warning would be 

at least as effective as an indefinite 

warning. 

At the same time, there is no 

uncertainty that seat belts save lives, 

and there would appear to be little 

uncertainty that, regardless of 

assumptions and estimates, the 

monetized net benefits of a long 

warning would almost certainly be 

positive, because almost all subject 

vehicles already provide a seat belt 

warning for the front outboard seats, 

and any necessary changes to 

implement a longer warning (such as reprogramming to optimize the warning 

characteristics) would likely be quite 

low-cost. Moreover, although an 

indefinite-duration warning would 

likely require some re-engineering, 

audio-visual seat belt warnings are a 

longstanding and established 

technology, so there should be no 

concerns about the technical feasibility 

of such a warning. 

Of course, effectiveness and 

component cost are not the only 

considerations in deciding what 

duration to require. Consumer 

acceptance is also crucial, and the 

Safety Act requires NHTSA to consider 

it. NHTSA is cognizant of—and takes 

seriously—likely disbenefits from 

annoyance. Many of the commenters’ 

criticisms relate to the potential for an 

indefinite warning being annoying. In 

the NPRM the agency acknowledged 

past studies that found a correlation 

between annoyance and warning 

effectiveness.141 142 Elsewhere in this 

preamble we discuss the modifications 

NHTSA has made to the proposal in 

response to the comments in order to 

address concerns related to consumer 

acceptance, such as including a speed 

threshold for the indefinite audible 

warning. However, despite the steps the 

agency is taking to make the audible 

warning acceptable, it is not 

unreasonable to expect that there will be 

some level of annoyance, particularly 

from hardcore non-belt users, for an 

effective reminder. Similarly, it would 

be expected that with annoyance would 

come some level of distraction. 

Consequently, we would expect some 

level of lack of acceptance from 

hardcore non-users.143 Additionally, we 


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assume that an indefinite audible warning will not 

cause occupants who ‘‘never’’ use a seat belt to 

begin using a seat belt. This is a change from the 

PRIA, which assumed that the indefinite reminder 

would be effective for such occupants. We note that 

the NPRM incorrectly stated that ‘‘for the purposes 

of our effectiveness (and benefits) analysis, we 

conservatively assume that the increase in belt use 

would be due entirely to part-time nonusers’’ (pg. 

61711, n.231). 

144Mazzae, E.N., Baldwin, G.H.S., & Andrella, 

A.T. (2018, October). Performance assessment of 

prototype seat belt misuse detection system. (Report 

No. DOT HS 812 593). National Highway Traffic 

Safety Administration. NHTSA has chosen not to 

implement measures to harden the systems against 

misuse at this time, for the reasons expressed in the 

NPRM. However, the agency will monitor this 

situation and act in the future if need be. 

145Buckling Up: Technologies to Increase Seat 

Belt Use. Special Report 278, Committee for the 

Safety Belt Technology Study, Transportation 

Research Board of The National Academies (2003), 

pg. 40. 

146 2016 MVOSS, pg. 71(Fig. 53). 

147 2016 MVOSS, pg. 79 (Fig. 55). 

148 2016 MVOSS, pg. 89 (Fig. 64). 

149 2016 MVOSS, pg. 90 (Fig. 65). 

150 2016 MVOSS, pg. 88 (Fig. 63). 151For example, as we stated in the NPRM (pg. 

61705), the 2004 Transportation Research Board 

Report notes that part-time belt users are the 

primary (not sole) target group for seat belt 

warnings. 152 Kidd, D.G., and Singer, J. (2019, April) The 

effects of persistent audible seat belt reminders and 

a speed-limiting interlock on the seat belt use of 

drivers who do not always use a seat belt. Insurance 

Institute for Highway Safety, Westat, Inc. 

153This EV-specific language is discussed in 

Section VI.C.1. 

understand that this lack of acceptance 

could lead to some level of misuse or 

attempts to defeat the system for some 

in this same group. The agency has 

studied such potential misuse in 

previous research 144, and, as noted 

earlier, some of the Kidd study 

participants circumvented both the 

indefinite and 90 second audible 

warnings. 

NHTSA, however, believes that the 

population of occupants who will not 

respond to the warning by fastening the 

belt will be relatively small in number; 

as noted earlier, about 5.4 percent of 

occupants never or seldom use a seat 

belt. Moreover, we note that NHTSA’s 

survey data does suggest that even 

though ‘‘[s]eat belt reminder systems are 

likely to have little effect on hard-core 

nonusers who choose not to buckle 

up’’,145 some individuals who report 

never using a belt would likely be 

responsive to a reminder. When asked 

about their reasons for not using a seat 

belt, many people who report never 

using a seat belt give reasons suggestive 

of some amenability to a reminder (for 

example, only driving a short distance 

or forgetting), as opposed to reasons that 

indicate general opposition to belts 

(such as e.g., ‘‘don’t like being told what 

to do’’ or ‘‘belts sometimes cause 

injuries’’).146 In addition, many of those 

who never or rarely used a belt do not 

necessarily hold strongly negative 

beliefs about seat belts or seat belt use. 

For example, of drivers who never or 

rarely used a belt, 43 percent do not 

report disliking seat belts or finding 

them annoying; 147 about half do not 

believe that the belt is just as likely to 

harm them as help them; 148 and only 20 

percent report that putting on a seat belt 

makes them worry.149 And, when asked 

whether they would want a belt on in 

a crash, 63 percent of drivers who never 

or rarely use a belt strongly or somewhat 

agreed that they would want to be 

wearing a belt in a crash.150 This is 

consistent with NHTSA’s other 

research, which acknowledges that 

occupants who sometimes use belts are 

the primary target for seat belt 

reminders, but not necessarily the only 

target.151 Therefore, while our benefits 

analysis excludes occupants who never 

use a seat belt, we would expect at least 

some of these nonusers to begin using 

a seat belt. Accordingly, overall we 

believe that the public will accept the 

required reminder, and that it will not 

negatively impact public acceptance of 

warnings in general. 

On the whole, in light of the 

uncertainty about the duration that will 

be most beneficial; the unquestioned 

benefit and effectiveness of seat belts; 

the relatively small proportion of users 

who will choose not to use the belt and 

will either experience annoyance from 

the reminder or choose to circumvent it; 

and recognizing that in MAP–21 

Congress removed the statutory 

limitation on the required duration for 

an audible seat belt warning, NHTSA is 

choosing to require an audible warning 

that lasts until the front outboard 

occupants are belted (again, subject to 

additional triggering criteria, such as the 

10 km/h speed threshold). 

The other points raised by the 

commenters also do not persuade us to 

require a shorter warning. Commenters 

opposed to the indefinite warning also 

argued that it would be desensitizing. 

This conclusion does not seem to be 

consistent with the IIHS study where 

the findings indicate that a long 

duration warning may have a greater 

impact on seat belt use,152 and the 

comments by Honda and GM that 

warnings lasting 90 or 34 seconds 

(respectively) may be more effective 

than an indefinite warning. As to the 

comments that a seat belt warning will 

cause other warnings to not be 

recognized, we address this in the 

Section VI.C.4. As to the comment by 

Auto Innovators that an indefinite 

warning in the front would be 

inconsistent with the agency’s 

conclusion to limit the rear seat warning 

to 60 seconds because a longer warning 

could be distracting, the commenter did 

not provide the full context of the 

rationale for the agency’s conclusion. 

Our conclusion was partially based on 

the fact that the rear seat warning 

system does not require occupant 

detection. Because of this, the rear seat 

belt warnings (particularly what the 

NPRM referred to as positive-only or 

full-status systems, which provide 

information on belted, as well as 

unbelted, occupants) function more as a 

source of information for the driver, 

rather than as a true ‘‘warning’’ for an 

unbelted occupant. It was for this reason 

that we believed that it was not 

necessary to require a particularly longlasting warning for the rear. This logic 

does not apply to the front seats, for 

which occupant detection is either 

required or (for a driver’s seat) can be 

assumed. Accordingly, the audio-visual 

signal functions more as a warning than 

as a source of information, because it is 

not activated for a belted occupant. 

Audible Warning Activation 

The final rule incorporates a twophased audible warning. The first-phase 

audible warning is required to activate 

whenever the ignition switch is placed 

in the ‘‘on’’ or ‘‘start’’ position (or upon 

manual activation of the propulsion 

system, but prior to the vehicle being 

placed in ‘‘possible active driving 

mode’’ as defined by FMVSS No. 

305),153 the seat is occupied, and the 

seat belt is not in use. The first-phase 

audible warning must continue for 30 

seconds, until the seat belt that triggered 

the warning is in use, until the seat is 

no longer occupied, or until the secondphase warning activates, whichever 

comes first. The second-phase audible 

warning must activate and remain active 

when the vehicle speed is equal to or 

greater than 10 km/h (6.2 mph), the seat 

is occupied, and the seat belt is not in 

use. 

The agency believes that this change 

in the triggering strategy from that 

specified in the NPRM will address 

many of the concerns expressed by the 

commenters related to potential user 

annoyance such as when the vehicle 

occupant is in a stationary vehicle, e.g., 

interacting with non-driving aspects of 

the vehicle or waiting for the vehicle’s 

climate control. This change will also 

ameliorate the concerns related to EVs 

triggering the indefinite warning while 

being on, but stationary (Auto Hold 

applied). 

We are rejecting advice from 

commenters suggesting requiring only a 

visual warning upon vehicle start. Such 


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154 DOT 2009 Seat Belt Study at pg. 65. 

155 IIHS allows for a 30-second delay at speeds 

between 10 and 40 km/h (6.2 and 24.9 mph) and 

a 2-second delay at speeds at and above 40 km/h 

(24.9 mph). 

156Wang, J.-S. (2022, May). MAIS(05/08) injury 

probability curves as functions of delta V (Report 

No. DOT HS 813 219). National Highway Traffic 

Safety Administration. 

157At 25 km/h (15.5 mph) there is a 41 percent 

probability of MAIS1 and 4.3 percent MAIS2. 

a requirement would not even be 

consistent with the 4–8 second audible 

warning requirement currently in 

FMVSS No. 208. The initial 30-second 

audible warning remains important for 

the reasons expressed in the NPRM for 

why we want such a warning to initiate 

at vehicle start. We believe basing the 

trigger on the ignition switch is 

preferable to delaying the warning until 

the vehicle is placed in gear because the 

proposed requirement would make it 

more likely that the occupants fasten 

their belts before the vehicle is in 

motion.154

The selection of 30 seconds is 

consistent with the ECE R16 start-up 

visual warning duration and the rear 

seat change-of-status audible warning 

for this final rule. We believe the 30- 

second audible warning will maintain 

the agency’s goal of an effective warning 

at the start of a trip, while increasing the 

level of acceptance from what might be 

the case if the start-up warning 

remained indefinitely active. The initial 

30-second audible warning will have 

the same characteristics as the rear seat 

change-of-status audible warning, i.e., 

the warning may be continuous or 

intermittent. If intermittent, inactive 

periods longer than 3 seconds will not 

be counted toward the total duration of 

the warning and no gap longer than 10 

seconds is allowed. These are also 

characteristics required by the ECE R16 

audible warning, except for the 10- 

second gap limit, which is required by 

Euro NCAP. 

The second-phase audible warning is 

important to encourage belt use for 

occupants that would otherwise wait 

out a finite warning and not buckle their 

belt. The 30-second start-up warning 

alone would have very little additional 

safety benefit, given that nearly all new 

vehicles already have audible warnings 

of this length or greater. Additionally, 

the agency agrees with commenters that 

a speed-based approach for the 

indefinite audible warning should 

address pick-up and drop-off situations 

that could lead to consumer backlash, 

particularly for frequent belt users. 

The selected speed threshold (10 km/ 

h (6.2 mph)) is aligned with the IIHS 

rating system and Rivian’s 

recommendation. ECE R16 also uses a 

10 km/h (6.2 mph) threshold for its 

definition of when a vehicle is in 

normal operation, and 10 km/h (6.2 

mph) is within its maximum allowed 

speed threshold (25 km/h (15.5 mph)). 

The selected speed threshold is meant 

to address such scenarios as where the 

vehicle is parked, driving to a mailbox, 

on a long driveway, driving in a parking 

lot/garage, or dropping off passengers, 

but is not high enough that vehicles will 

be able to drive on roadways and not get 

a warning. Once the vehicle is traveling 

below 10 km/h (6.2 mph), the warning 

may deactivate. We are not allowing for 

any delay in the warning after the speed 

threshold is reached as is allowed by the 

IIHS rating,155 as we do not believe such 

a delay is necessary to achieve our goal 

of limiting the activation of the audible 

warning for regular belt users and 

would be counterproductive (i.e., 

increase the amount of time at which 

unbelted occupants do not get a 

warning). 

The agency is not allowing 

manufacturers the choice to initiate the 

warning based on a combination of 

speed, timing, or distance traveled, such 

as is the case for the second level ECE 

R16 warning. We believe that vehicle 

speed is the most relevant parameter 

and that 10 km/h (6.2 mph) limit is 

sufficiently low to achieve the agency’s 

safety goals. Analysis of agency field 

data indicates that a 10 km/h (6.2 mph) 

delta V frontal crash shows a 28 percent 

probability of MAIS1 and 1.7 percent 

MAIS2 injuries and essentially no risk 

of higher level injury, whereas at 20 km/ 

h (12.4 mph) there is a 39 percent 

probability of MAIS1 and 4.0 percent 

MAIS2.156 Though still low probability, 

this is a 2.4-fold increase in the risk of 

MAIS2.157 Although equating vehicle 

travel speed to delta V would tend to 

overestimate occupant injury, the 

results are directionally correct, and a 

higher speed threshold (or delay in 

initiating a particular speed threshold) 

would tend to increase injury risk. 

We acknowledge that the data show 

that MAIS1 and MAIS2 injuries, which 

are meaningful safety concerns, occur 

frequently in collisions with delta V at 

10 km/h, and that this final rule appears 

to depart from the NPRM’s stated belief 

that seat belts provide a safety benefit 

even at lower speeds, regardless of the 

direction of motion. We also grant that 

in rare cases a vehicle traveling at a 

speed below 10 km/h (6.2 mph) may be 

struck by another vehicle traveling at a 

higher speed and that seat belt 

protection would be beneficial in such 

cases. However, we believe that the 

resulting increase in the warning 

systems’ overall level of acceptability 

(which is an important consideration for 

both meeting the safety need and 

practicability), particularly for those 

that regularly wear seat belts, will 

outweigh the negative effects from nonactivation of the warning system below 

10 km/h. 

The second phase indefinite audible 

warning will also serve as a change-ofstatus warning, except that now that the 

indefinite audible warning is speed 

based, there is no need to relate 

activation to the gear selection or door 

opening status as was proposed. The 

fact that the speed threshold is exceeded 

is a sufficient reason for the audible 

warning to be active. 

With respect to AVIA’s comment 

about modifying the provision for 

resetting the system when a door is 

opened for the front seats to address 

novel seating configurations, NHTSA 

believes these types of vehicles, 

specifically vehicles without a driver’s 

seating position where all seats in the 

front and/or rear rows may be accessed 

via a common door, are beyond the 

scope of this rule. The agency did not 

develop the finalized seat belt warning 

requirements with these specific 

vehicles in mind. In any case, AVIA’s 

concern about exposure to the proposed 

audio-visual change-of-status warning 

in these vehicles under the scenario it 

described in its comment is largely 

addressed by the finalized requirements 

for the front seat for change-of-status 

events, which only requires the 

activation of a visual warning in a dropoff scenario given the speed trigger 

criteria for the audible component. 

Visual Warning 

The final rule requires that a visual 

warning activate and remain active 

whenever the ignition switch is in the 

‘‘on’’ or ‘‘start’’ position (or the 

propulsion system is activated), the seat 

is occupied, and the seat belt is not in 

use. The final rule condenses the 

proposed ‘‘start of trip’’ and ‘‘change-ofstatus’’ visual warnings into a single 

requirement and changes the proposed 

activation triggers in a few ways. 

We agreed with Honda’s comment 

that under the proposed rule, if an 

occupant unbuckled while the vehicle 

was in park, no warning would be 

required to activate, even if the vehicle 

were subsequently placed in gear and 

commenced moving. We therefore 

believe that a ‘‘change-of-status’’ visual 

warning should not be limited to when 

the vehicle is in a forward or reverse 

drive mode. Accordingly, for the visual 

warning, we removed the activation 

triggers that referred to the ignition 

switch being placed in the ‘‘on’’ or 

‘‘start’’ position and to the transmission 


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158See Section VI.B.5. 

159See DOT 2009 Seat Belt Study at pgs. 67–68. 

160 Id. 

161Section 8.4.2.1.1. 

162Section 3.4.1.1. We note that the NPRM 

incorrectly referenced a prior version of the Euro 

NCAP protocols which specified visibility to the 

passenger. NHTSA appreciates Auto Innovators’ 

comment noting that the referenced material was 

removed in v8.0 of the assessment protocol. 

gear position. (We have also made 

analogous changes to the regulatory text 

related to EVs. These changes are 

discussed in Section VI.C.1.) These 

changes will ensure that a warning is 

activated whenever the vehicle is on 

and a driver or front outboard passenger 

is in the seat and not belted. Because 

this only applies to the visual warning— 

and not the audible warning—we do not 

believe this will lead to issues with 

consumer acceptance, because a visual 

warning is not nearly as intrusive as an 

audible warning. (On the other hand, as 

we explain in the preceding section, we 

have modified the proposed triggers for 

the audible warning to limit the 

scenarios in which it will activate to 

address concerns with consumer 

acceptance.) Concerns with consumer 

acceptance are further allayed by the 

fact that the warning requirement is tied 

to seat occupancy, so there will not be 

nuisance alarms for an unfastened belt 

at an unoccupied seat. 

The finalized regulatory text also 

adopts Honda’s suggestion that the 

proposed change-of-status warning 

include seat occupancy as one of the 

triggering conditions. Because the front 

seats are either equipped with occupant 

detection or (for the driver’s seat) 

occupancy can be assumed,158 there is 

no reason to require a visual warning for 

an unoccupied seat. This also addresses 

the misuse case Honda identifies. 

Including seat occupancy as a trigger 

also allows us to further simplify the 

triggering logic for the visual warning by 

deleting the exception to the proposed 

change-of-status warning for when a 

front door on the same side of the 

vehicle as the seat belt triggering the 

warning is open. This language is now 

unnecessary because seat occupancy is 

one of the triggers for the visual 

warning—in a scenario where a driver 

or front outboard passenger unbuckles 

and disembarks, a visual warning is not 

required because the seat is no longer 

occupied, and any reference to a door 

opening is unnecessary. 

We also implemented Auto 

Innovators’ recommendation to delete 

the proposed restriction that the audiovisual warning is permitted to activate 

only to comply with the requirements in 

this rule. 

The finalized requirements for the 

visual warning are also generally 

consistent with the broad tenor of the 

comments on the proposed audio-visual 

warning, which, as we discussed earlier, 

were primarily concerned with the 

proposed indefinite audible warning 

and the proposed triggers for that 

warning. For example, we agreed with 

Mercedes and NADA that the change-ofstatus warning should better harmonize 

with ECE R16 and now require only a 

visual warning if the vehicle is 

stationary or travelling at low speeds. 

We did disagree with the commenters 

who suggested a shorter visual warning 

(at or below the 30 seconds required in 

ECE R16) because, among other things, 

we believe both that a longer visual 

warning will be more effective than a 

shorter warning and also that a long 

visual warning does not pose the same 

consumer acceptance concerns as does 

a long audible warning. 

4. Visibility of Visual Warning for Front 

Outboard Passenger Seat Belt 

We proposed requiring that if there is 

a driver’s designated seating position, 

the visual warning for the driver’s seat 

belt must be visible from the driver’s 

seat and the visual warning for the front 

outboard passenger seat belt must be 

visible from both the driver’s seat and 

the front outboard passenger seat. We 

did not propose to specify more detailed 

criteria for location or visibility of the 

telltale. (For discussion of vehicles with 

no driver’s designated seating position, 

such as ADS-equipped vehicles without 

any manual driving controls, see 

Section VI.C.7.) We proposed requiring 

that the visual warning for the front 

outboard passenger seat belt be visible 

to both the driver and the front outboard 

passenger because NHTSA’s study on 

front seat belt warning systems suggests 

that visual warnings for front outboard 

passenger seat belts are more effective 

when they are visible to the passenger 

as well as the driver.159 We tentatively 

believed it would be practicable for 

manufacturers to comply with this 

requirement; for example, the warning 

could be located in the center console 

display (which might be a salient place 

to present visual displays, both because 

of its location and because it may allow 

larger size icons or text).160 Some 

manufacturers already provide a 

passenger seat belt warning in close 

proximity to the passenger air bag status 

indicator, which is visible to both the 

driver and front passenger. 

We did not propose more detailed 

criteria for the location or visibility of 

the telltale as, for example, are provided 

in FMVSS No. 208 S19.2.2 for the 

passenger air bag telltale. A visual 

warning for the driver’s seat belt has 

been required since the early 1970s and 

we are not aware of any issues with the 

visibility of that telltale, so we 

tentatively believed more detailed 

requirements to be unnecessary. 

IIHS’s ratings system specifies for the 

front outboard passenger seat that a 

visual signal must be displayed in the 

instrument panel, overhead panel, or 

center console, indicating an unfastened 

belt. 

ECE R16 specifies only that the visual 

warning must be readily visible and 

recognizable in the daylight and at 

nighttime by the driver and 

distinguishable from other alerts.161

Euro NCAP recommends that the visual 

signal must be clearly visible to the 

driver, without the need for the head to 

be moved from the normal driving 

position (such as in the instrument 

panel, head-up display, rear-view 

mirror, or center console).162

Comments 

A number of commenters, such as 

Auto Innovators, Mercedes, Ford, 

Nissan, HATCI, NADA, Toyota, and 

Honda, commented that the rule should 

require only that the front outboard 

passenger seat visual warning be visible 

to the driver. Mercedes noted that the 

agency did not provide any insight on 

how to achieve the passenger visibility 

requirement. Ford commented that a 

visual warning for front row passenger 

belt use that is visible to both driver and 

passenger may be unnecessary, overly 

complex to implement, and delay 

implementation. Auto Innovators and 

Mercedes commented that requiring 

passenger visibility of the visual 

reminder would be inconsistent with 

ECE R16 and Euro NCAP. 

Auto Innovators, Nissan, HATCI, 

Mercedes, Ford, and NADA all 

commented that the driver has primary 

responsibility to notify and ensure 

occupants fasten their seat belts and that 

the occupant in the front passenger seat 

will be alerted by the audible warning 

if the seat belt is not fastened. Honda 

noted that the primary mechanism for 

encouraging seat belt use is the audible 

alarm, and that the visual indicator 

primarily serves to explain the cause of 

the alarm. Honda stated that because the 

driver can hear the audible alarm and 

interpret the visual alarm, the passenger 

telltale becomes a matter of 

convenience. 

Honda also commented that the 

proposed outboard passenger visibility 

requirements have questionable merit 

because the DOT 2009 Seat Belt Study, 

the research upon which much of the 

expected benefits of the requirement 


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163 DOT 2009 Seat Belt Study at pg. 66. 

164We also note that this research noted the 

efficacy of audible alerts, but suggested not using 

an alert audible to drivers for the passenger’s belt 

due to consumer acceptance concerns. However, as 

discussed in the NPRM and elsewhere in this final 

rule, research shows that consumers are now far 

more accepting of audible alerts. Therefore, the 

audible alert required by this final rule may serve 

to more effectively perform the communication role 

that this research suggested the visual alert to the 

passenger did. See DOT 2009 Seat Belt Study at pgs. 

67–68. 

165Other research referenced in the NPRM that 

suggested a passenger visibility requirement might 

increase effectiveness was preliminary on this point 

and precluded firm conclusions. For example, some 

research noted that it is not evident to what extent 

improved effectiveness is due to direct message 

effects on the passenger and to what extent it may 

be due to more complex social dynamics between 

the driver and the passenger. We also cited studies 

that suggest that center console display locations 

might be more effective than dashboard display 

locations but were not conclusive due to other 

differentiating factors in the visual designs, such as 

character size, display size, and color, which may 

be covaried. See N. Lerner et al. (2007). 

Acceptability and Potential Effectiveness of 

Enhanced Seat Belt Reminder System Features. 

(Report No. DOT HS 810 848). National Highway 

Traffic Safety Administration; DOT 2009 Seat Belt 

Study. 

166 Given that many manufacturers currently 

provide visual alerts in the center console or in 

proximity to the passenger advanced air bag signal, 

we maintain our confidence that in many cases the 

cost would be limited and encourage manufacturers 

to voluntarily provide visual warnings to the 

passenger. 

was based, has limitations. Honda noted 

aspects of the study and the design of 

the warnings used in the study, such as 

unusually large and aggressive 

indicators, which may limit the 

effectiveness conclusions that can be 

drawn from the study. Honda 

commented the study noted that in 

actual tests the most effective seat belt 

warning modality was the audible 

chime that repeated at a frequent 

interval, which suggested that the 

placement of the passenger telltale being 

visible to the passenger is of 

questionable efficacy. 

Auto Innovators, HATCI, Nissan, 

Mercedes, Ford, NADA, and Honda all 

commented that requiring that a 

warning also be visible to the front 

outboard passenger would require 

significant interior redesign of displays. 

Auto Innovators commented that this 

requirement would likely require either 

all visual warnings be in a central 

position (outside of the instrument 

cluster) so that they are visible to both 

the driver and right front passenger, or 

a second visual warning located in a 

central position to solely communicate 

the status of the passenger seat belt. 

Several of the commenters stated that 

this requirement would necessitate 

additional lead time. 

Toyota, Auto Innovators, and Honda 

commented that requiring front 

outboard passenger visibility would be 

unnecessary and inconsistent with the 

agency’s proposed approach to the rear 

seat reminder requirements. They 

emphasized that the agency did not 

propose a requirement that visual 

warnings/indicators be visible to rear 

seat occupants, and that the agency is 

being inconsistent by proposing a 

requirement that the front seat visual 

reminder must be visible to the 

passenger, while the rear seat visual 

reminder only must be visible to the 

driver. These commenters expressed 

that the visual alert visible to the driver 

combined with the required audible 

alert would be sufficient to ensure that 

occupants in both the rear and the front 

passenger seats know their belt status. 

Auto Innovators and Honda 

commented that while FMVSS No. 208 

specifies requirements for a telltale to 

indicate the status of the passenger air 

bag for those seated in the front 

outboard passenger seat, this does not 

create a precedent, or support the need 

for, a similar front outboard passenger 

belt reminder telltale. Auto Innovators 

and Honda argued that with respect to 

seat belt use, the passenger can verify, 

based on a visual or manual check, 

whether their seat belt is buckled. This 

is not the case for air bag systems. 

Agency Response 

The final rule requires that the front 

outboard passenger seat belt visual 

warning be visible only to the driver, 

with two exceptions related to ADSequipped vehicles. In response to 

comments, we have decided not to 

require that the visual warning for the 

front outboard passenger seat belt be 

visible from the front outboard 

passenger seat. Retaining this 

requirement for the driver is critical for 

generating a communication dynamic 

between the driver and passenger, 

which is discussed further in this 

section and in Section VI.C.3 below. 

Manufacturers retain the flexibility to 

incorporate a visual signal that is visible 

to both the driver and front outboard 

passenger (or an additional signal 

visible to the passenger), and many 

already do. The final rule harmonizes 

with ECE R16 and Euro NCAP. It also 

matches the requirements for the 

visibility of alerts for the front passenger 

and rear seat belt reminders. 

Although there is limited information 

available on the safety benefits and 

compliance costs of a passenger 

visibility requirement, what information 

we have suggests that both would likely 

be low, at least in the context of this 

final rule. In this instance we feel that 

the relatively minimal benefits do not 

justify the costs that could be realized. 

With respect to benefits, because this 

final rule requires an audible alert, it 

(along with the visual warning provided 

to the driver) can serve the role 

provided by a visual warning to the 

passenger. The primary study we used 

to support this proposal does suggest 

that visual alerts may be more effective 

when the passenger sees them. It also 

notes that the visual alert may present 

an opportunity for communication 

between driver and passenger to prompt 

passenger belt usage.163 However, given 

that this rule requires an audible 

warning which can initiate this 

communication, the visual alert for the 

passenger would likely serve a 

supporting role, limiting its added 

benefit.164

It is also worth noting that under the 

requirements of this final rule there are 

only rare scenarios in which a visual 

alert is the only alert required to be 

active. We are requiring an indefinite 

audible alert if the vehicle is traveling 

at or over 10 km/h (6.2 mph) and a 30 

second minimum start-of-trip audible 

warning if there is an unbelted front 

passenger. Therefore, the only situation 

in which the visual alert is the only 

active warning is when the vehicle is 

traveling under 10 km/h (6.2 mph) (or 

stopped) and the start-of-trip warning 

has elapsed. These situations are 

limited, and field data shows only small 

risks of injuries with severity above 

MAIS1 and almost no risk of injuries 

with severity above MAIS2 in frontal 

crashes at these speeds. Therefore, 

while research suggests the proposed 

visibility requirement might generate 

some safety benefits, given the structure 

of this final rule those additional 

benefits are hard to determine and may 

only be minor.165

Regarding costs, we disagree with 

commenters about the size and scope of 

the costs associated with incorporating 

a signal visible to the passenger. 

However, we understand that, 

depending on how manufacturers 

decided to implement the proposed 

requirement, there could be more than 

de minimis costs for certain vehicles 

and these costs may outweigh the 

benefits of this requirement.166 Given 

this potential imbalance and our belief 

that most if not all of the desired 

benefits will be achieved by the 

indefinite audible warning, we are only 

finalizing that the front passenger’s 

visual seat belt warning be visible to the 

driver. 

This approach is consistent with the 

approach we took for the rear seat belt 

warning. In the NPRM, we did not 

propose that the rear seat visual warning 

be visible to the rear passenger because 


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167An ADS-Equipped Dual-Mode Vehicle is 

defined as ‘‘[a] type of ADS-equipped vehicle 

designed for both driverless operation and 

operation by a conventional driver for complete 

trips.’’ SAE J3016_201806 Taxonomy and 

Definitions for Terms Related to Driving 

Automation Systems for On-Road Motor Vehicles. 

168Occupant detection systems are currently used 

for front outboard passenger seating positions to 

comply with the advanced air bag requirements in 

FMVSS No. 208. However, this is not the case for 

driver’s designated seating positions, which do not 

have the same considerations. 

169Specifically, Honda recommended the changeof-status warning should be revised to read as 

follows: ‘‘An audio-visual warning must activate 

when the ignition switch is in the ‘on’ or ‘start’ 

position, the vehicle is in forward or reverse drive 

mode, the seat is occupied (other than the driver’s 

seat for vehicles with a designated driver seating 

position), and the status of the seat belt changes 

from in use to not in use, unless a front door on 

the same side of the vehicle as the seat belt 

triggering the warning is open, in which case a 

warning is not required and the system may 

consider this as a new trip with respect to that seat 

belt and reset the warning system.’’ 

we did not believe that the benefits 

would outweigh the costs (viewed 

qualitatively). On the other hand, the 

NPRM did propose this for the front 

outboard passenger seat belt warning, 

because in that case we did expect the 

benefits to be greater than the costs. We 

now agree with the commenters, 

however, that because of the relatively 

low benefits; potentially non-de 

minimis costs for at least some vehicles; 

and the interplay between the visual 

and audible signals, that it is 

appropriate not to require that the visual 

warning for the front outboard 

passenger be visible to that passenger. 

We also wish to clarify the purpose of 

our reference, in the NPRM, to the 

advanced air bag visual signal because 

Honda’s and Auto Innovators’ 

comments suggest it may have caused 

some confusion. In the context of 

visibility, we referenced the advanced 

air bag telltale for the passenger only to 

indicate that it provides a location some 

manufacturers already use for a visual 

signal that is visible to the passenger. 

We did not intend to make any 

statements about the purpose of these 

signals within the structure of the 

FMVSS, their relative safety benefits, or 

the meanings they convey. 

Finally, we believe it is important to 

address two potential future situations 

where only requiring the visual warning 

to be visible to the driver would not be 

sufficient. The first is for dual-mode 

ADS-equipped vehicles that still have a 

driver’s seat and driving controls.167 For 

such vehicles the driver’s seat could 

remain unoccupied throughout the 

vehicle’s operation. In this situation, 

limiting the visibility of the front seat 

warnings to the driver’s seat would 

result in the passenger not seeing the 

warning. The second is for ADSequipped vehicles without a driver’s 

designated seating position. For the 

former, the final rule requires that the 

visual warning for the front outboard 

passenger seat belt must be visible from 

the front outboard passenger seat, and 

for the latter the final rule requires that 

the visual warning for each outboard 

designated seating position be visible 

from each outboard passenger seating 

position. 

5. Front Seat Occupant Detection and 

Seat Occupancy Criteria 

In the NPRM, we proposed a single 

compliance option that requires a startof-trip audio-visual warning that lasts 

until the seat belt at any occupied front 

outboard seat is fastened. We proposed 

that the warning system consider the 

front outboard passenger seating 

position ‘‘occupied’’ when an occupant 

or dummy that weighs at least 46.7 kg 

(103 lb) and is at least 139.7 cm (55 in) 

tall is seated in the seat, which matches 

the specification in FMVSS No. 208 for 

a person who is used as an alternative 

for the 5th percentile adult female test 

dummy for compliance testing of 

advanced air bag systems using static 

suppression. The NPRM also proposed 

giving the manufacturers the option to 

use a human being instead of using test 

dummies for testing purposes. Requiring 

occupant detection for front outboard 

passenger seating is consistent with 

Euro NCAP and IIHS ratings protocols, 

and the specification is consistent with 

Euro NCAP and the ECE R16 test 

procedures. IIHS does not specify any 

occupancy criteria for either front 

outboard seating positions. 

However, the NPRM was unclear 

about the occupancy requirements 

pertaining to the driver’s designated 

seating position. The proposal included 

occupancy as a condition to trigger the 

warning for the driver’s seat. The 

proposed test procedures also specified 

they applied to ‘‘front designated 

seating positions.’’ Thus, the test 

procedures would have applied to both 

front outboard seating positions and 

therefore may have required NHTSA to 

place a dummy or a human being in the 

driver’s seat to establish occupancy for 

the test. However, we did not propose 

to define ‘‘occupied’’ for the driver’s 

seat.168

Euro NCAP and IIHS allow occupancy 

for the driver’s seat to be assumed. ECE 

R16 does not require the driver’s seat to 

be occupied in its test procedures for 

the start-of-trip warning. 

For the change-of-status warning for 

the front outboard passenger seat, 

NHTSA did not propose that the seat 

must be occupied when the buckle is 

unfastened to trigger the alarm. On the 

other hand, IIHS protocol requires 

occupancy to trigger the change-ofstatus warning and ECE R16 allows the 

warning to be discontinued if the seat 

which triggered the warning is no longer 

occupied. This is also true of IIHS’s and 

ECE R16’s specification for the driver’s 

seat. 

Comments 

IEE, Honda, and Consumer Reports 

expressed support for requiring 

occupant detection for the front 

outboard passenger seat and for using 

occupancy as an element of the trigger 

for the front outboard passenger seat 

warning. Consumer Reports commented 

that it agrees with NHTSA’s decision to 

align with Euro NCAP and require an 

occupant detection system for the front 

outboard passenger seat. Consumer 

Reports further explained that occupant 

detection is already widely deployed in 

these seats, either as part of an advanced 

air bag system or as part of a voluntary 

seat belt warning system, reinforcing the 

feasibility of equipping vehicles with 

occupant detection technology. IEE 

commented that it supports NHTSA’s 

proposal to use the 5th percentile 

female as occupant detection criteria for 

the front outboard passenger seat 

because it aligns with the requirements 

for the sensors installed in the front 

passenger seats of vehicles complying 

with the advanced air bag requirements 

of FMVSS No. 208 and the same sensors 

are widely used for the voluntary front 

passenger seat belt warning systems. 

Honda commented requesting 

clarification on occupant detection for 

the driver’s seat. Honda explained that 

the NPRM proposed that the start-of-trip 

warning for front outboard seats must 

activate ‘‘if the seat is occupied,’’ among 

other conditions. It commented that 

while this language is an appropriate 

condition for the front outboard 

passenger seat, it is unnecessary for the 

driver seat. Honda further commented 

that FMVSS No. 208 does not 

contemplate an occupant detection 

system because a driver is assumed to 

be present in a conventional vehicle. 

Honda recommended that this language 

be revised so that occupant detection 

requirements are not unintentionally 

prescribed for the driver’s seat. 

Honda commented that if a speed 

threshold is not adopted for the changeof-status warning and the proposed 

transmission trigger is retained, NHTSA 

should also use occupant detection as a 

trigger.169 Honda believes this 

recommendation would resolve a 


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170 49 CFR part 572, subpart O. 

171These are the bottom of the ranges specified 

in FMVSS 208 S29.1(f) for the weight and weight 

of a human female who may be used in certain of 

the advanced air bag testing in place of the 5th 

percentile female dummy. 

172To be clear, although a vehicle might be 

placed in these conditions without an occupant in 

the driver’s seat, this is not a typical or likely 

scenario in the field because it is the driver that 

initiates these conditions (other than for vehicles 

without a driver’s designated seating position). 

173The activation criteria are (1) the vehicle’s 

ignition switch is moved to the ‘‘on’’ position or to 

the ‘‘start’’ position; and (2) the driver’s lap belt is 

not in use, as determined either by the belt latch 

mechanism not being fastened, or by the belt not 

being extended at least 4 inches from its stowed 

position. 

misuse case in which someone buckles 

an empty seat and then unbuckles it. 

Honda expressed concern that under the 

proposal this type of scenario would 

require an unending alarm until the seat 

is re-buckled or the door is opened. 

Agency Response 

NHTSA appreciates IEE’s, Honda’s, 

and Consumer Reports’ support for 

requiring occupant detection for the 

front outboard passenger seat and for 

using occupant detection as an element 

of the trigger for the front outboard 

passenger seat warning. In addition, 

NHTSA received no comments in 

opposition to requiring vehicles to have 

occupant detection capability for front 

outboard passenger seats or for 

including front outboard passenger seat 

occupancy as one of the trigger 

conditions for the start-of-trip front 

outboard passenger seat belt warning. 

Likewise, NHTSA received no 

comments in opposition to specifying 

that the warning system consider a front 

outboard passenger seating position 

‘‘occupied’’ when an occupant or 

dummy that weighs at least 46.7 kg (103 

lb) and is at least 139.7 cm (55 in) tall 

is seated in the seat. We are finalizing 

these provisions proposed in the NPRM 

with some revisions to the final 

regulatory text for clarity. 

With respect to a driver’s seat, we 

have modified the proposal to clarify 

that the final rule does not require 

occupant detection for the driver’s seat. 

The final rule does specify seat 

occupancy as one of the criteria for 

activation of all of the required front 

seat belt warnings (the visual warning 

and first- and second-phase audible 

warnings). However, the final rule also 

provides manufacturers with three 

compliance options for certifying that a 

driver’s seat belt warning complies with 

these requirements. First, a 

manufacturer may certify that the 

system meets the requirements when 

the 5th percentile female test dummy 

described in part 572 170 of this chapter, 

as well as any larger dummy described 

in part 572, is seated in the seat. 

Second, a manufacturer may certify that 

the system meets the requirements 

when any human occupant that weighs 

46.7 kg (103 lb) or more and is 139.7 cm 

(55 inches) tall or taller is seated in the 

seat.171 Third, a manufacturer may 

certify that the system meets the 

requirements when, instead of seating a 

dummy or human, the seat is 

considered occupied when the ignition 

switch is in the ‘‘on’’ or ‘‘start’’ position 

(or the propulsion system is activated). 

Similar to the front outboard passenger 

seat, the first two options would 

necessitate occupant detection 

technology and is technology-neutral 

with respect to the type of occupant 

detection technology used. The third 

option is consistent with our 

understanding of how these systems 

currently work as well as the 

approaches taken by Euro NCAP and 

ECE R16, and essentially allows the 

vehicle to infer that the driver’s seat is 

occupied based on the fact that the 

vehicle has been turned on.172

We are finalizing the rule this way for 

three reasons. First, requiring that the 

system activates only when the seating 

positions are occupied reduces false 

activations, which is important both for 

effectiveness and consumer acceptance. 

Although this is a larger concern for 

long or indefinite reminders, it is also 

relevant for the start-of-trip 30-second 

audible warning. 

Second, requiring occupancy for the 

driver’s seat aligns the activation criteria 

for the front outboard passenger and 

driver’s seating positions. Although 

Honda suggested that regulatory 

language is not necessary because 

driver’s seat occupancy can be inferred, 

including it avoids confusion about 

when the warning needs to or can 

activate that could come from specifying 

different activation criteria. 

Third, the first and second 

compliance options provide 

manufacturers the flexibility to optimize 

systems for vehicles with a driver’s 

designated seating position, but which 

may be ‘‘on’’ without a driver in the 

vehicle, such as dual-mode vehicles 

equipped with ADS but which still have 

a driver’s seat and driving controls, as 

well as vehicles which use remote start. 

Because dual-mode vehicles could 

operate without an occupant in the 

driver’s seat, we do not believe that 

inferring or assuming occupancy (which 

Euro NCAP and ECE R16 do) fully 

accounts for these vehicles. Without the 

option to use occupant detection, these 

vehicles could be required to initiate the 

driver’s seat start-of-trip audible 

warning when the ignition switch is 

placed in the ‘‘on’’ position (or for an 

EV, when the propulsion system is 

activated. Such scenarios would 

therefore result in false positives. By 

allowing manufacturers to select the 

occupancy method, our approach is 

similar in application to the inference 

approach taken by Euro NCAP and ECE 

R16 for conventional vehicles, while 

being forward-looking for vehicles with 

ADS. 

To clarify, although adding an 

activation condition that the seat is 

occupied is a change to the current 

driver’s seat belt warning requirements 

in FMVSS No. 208, we do not intend it 

to increase the stringency of the existing 

requirement for the driver’s seat. The 

activation criteria for the current 

driver’s seat belt warning do not include 

seat occupancy.173 Although the final 

rule introduces an occupancy criterion, 

it does not require occupant detection 

technology for the driver’s seat. Indeed, 

we are not defining occupancy for the 

driver’s seat as we have for the front 

outboard passenger seat, and the test 

procedure for the third compliance 

option does not require placing a test 

dummy (or human) in the driver’s seat. 

Instead, under this final rule, 

manufacturers will have the discretion 

to choose the method by which the seat 

belt warning system determines whether 

the driver’s seat is occupied in the 

context of seat belt warning activation. 

The third option enables systems that 

do not use occupant detection to certify 

to occupancy, while the first and second 

options enable manufacturers, if they so 

choose, to certify using a test dummy or 

a person (respectively), which may 

enable them to optimize a system for 

vehicles which may not have a person 

in the driver’s seat at start-up. 

Finally, in response to a comment 

from Honda and to incorporate 

considerations for certain vehicles with 

ADS, the finalized regulatory text 

implements Honda’s suggestion that the 

proposed change-of-status warning have 

occupancy as one of the triggering 

conditions. Because in the final rule, the 

visual warning and the second-phase 

audible warning function as a changeof-status warning, the regulatory text for 

these warnings includes seat occupancy 

as one of the triggering conditions. 

C. Issues Common to the Front and Rear 

Seat Belt Warning Requirements 

1. Modification of Start-of-Trip Warning 

Trigger Related Ignition Switch Position 

To Accommodate EVs 

As noted earlier, the NPRM proposed 

that the activation of both the front and 

rear seat belt warnings be triggered 


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174Section 8.4.2.3.1. 

175Section 3.4.2.1 (front); section 3.4.3.1.1 (rear). 

176More specifically, the ‘‘placed in’’ language is 

used to specify the rear seat belt start-of-trip 

warning and the front seat belt first-phase audible 

warning but not the front seat belt visual warning. 

The front seat belt visual warning is required to 

‘‘activate and remain active whenever the ignition 

switch is in the ‘‘on’’ or ‘‘start’’ position (or the 

propulsion system is activated), the seat is 

occupied, and the seat belt is not in use’’ (emphasis 

added). Because this visual warning is also serving 

as a change-of-status warning, this text refers to the 

ignition switch being ‘‘in’’ the on or start position, 

not being ‘‘placed in’’ on or start. However, in order 

for the ignition switch to be ‘‘in’’ the on or start 

position, it must first be ‘‘placed in’’ that position. 

Accordingly, this language necessarily includes the 

start of the trip. Similar reasoning applies to the EVspecific language for the front seat belt visual 

warning. 

177NHTSA recently proposed to establish FMVSS 

No. 305a to replace FMVSS No. 305. The proposed 

FMVSS No. 305a refers to this state as ‘‘active 

driving possible mode.’’ However, the definition is 

the same. The terminology is originally from Global 

Technical Regulation No. 13. 

178 82 FR 44945, 44956. 

179We also anticipate that if a vehicle activates 

the propulsion system before the driver is inside the 

when, among other things, ‘‘the ignition 

switch is placed in the ‘on’ or ‘start’ 

position.’’ We also stated that this same 

condition appears in the existing driver 

seat belt warning requirements and is 

similar to ECE R16 and Euro NCAP. 

ECE R16 specifies that the first-level 

visual warning activates ‘‘when the 

safety-belt of any of the seats is not 

fastened and the ignition switch or 

master control switch is activated.’’ 174

In the NPRM we explained that we were 

not proposing to follow ECE R16 and 

refer to a ‘‘master control switch’’ 

because we did not believe it necessary 

to introduce this new term into FMVSS 

No. 208. The second-level warning and 

the change-of-status warning have 

different triggers that are all based on 

the vehicle being in motion. 

Euro NCAP similarly specifies that 

the visual signal activate ‘‘when the 

ignition switch is engaged (engine 

running or not)’’ and the seatbelt is not 

fastened.’’ 175 Like ECE R16, the audible 

and change-of-status warnings have 

different triggers, mostly related to the 

vehicle being in motion. 

The IIHS protocol similarly links the 

start-of-trip visual signal to the vehicle 

engine being ‘‘turned on (i.e., powered 

and capable of propulsion).’’ 

Comments 

Tesla requested that NHTSA broaden 

the definition of ‘‘ignition switch’’ to 

cover, for example, EVs which do not 

have one. As an example, Tesla noted 

that the ‘‘ignition switch’’ definition 

could be expanded to the moment when 

power is delivered to wheels to initiate 

vehicle motion. Tesla also requested 

clarity on the definition of ‘‘vehicle 

start-up.’’ Tesla noted that this 

clarification is especially important for 

EVs. 

Honda had similar concerns, noting 

that electrified vehicles may differ from 

traditional internal combustion vehicles 

in that they may not have a distinct 

moment when the ignition switch is 

turned ‘‘on’’ or ‘‘started.’’ Instead, 

Honda explained that these vehicles 

typically use automatic ‘‘wake’’ and 

‘‘sleep’’ modes, which are activated 

based on various sensing and detection 

algorithms. While Honda preferred that 

NHTSA reconsider using the ignition 

switch as a trigger, it requested 

clarification on the start-of-trip warning 

if it is retained. 

Agency Response 

We agree with Tesla and Honda that 

it would be helpful to provide clarity 

regarding warning activation for 

vehicles that do not have a traditional 

ignition switch or button with ‘‘on’’ and 

‘‘start’’ positions or conditions, which 

could be the case for EVs. Therefore, we 

are adding regulatory text to address 

these vehicles. 

The start-of-trip warnings (front seat 

belt visual and first-phase audible 

warnings and rear seat belt warning) are 

required to activate when (among other 

things) the ignition switch is ‘‘placed 

in’’ the ‘‘on’’ or ‘‘start’’ position or upon 

manual activation of the propulsion 

system, but before the vehicle is placed 

in ‘‘possible active driving mode’’ as 

defined by FMVSS No. 305.176 In 

developing this language, our goal was 

to specify a time in the start-up process 

to begin the start-of-trip warning for EVs 

that is roughly the same as the time we 

specified for vehicles with a 

conventional ignition switch such that 

the safety benefits for EVs would be the 

same as for ignition-equipped vehicles. 

For an ignition-equipped vehicle, while 

in the ‘‘on’’ position the vehicle 

electrical systems have been powered. 

While in the ‘‘start’’ position, the engine 

has been started and in this state a 

conventional vehicle is ready to be 

placed in a drive mode. An additional 

consideration is that, for an ignitionequipped vehicle certified to the option 

that the system determines the driver’s 

seat is occupied through movement of 

the ignition switch to both the ‘‘on’’ or 

‘‘start’’ position, the driver is presumed 

to be in the vehicle to initiate the action. 

However, what actions by the driver 

initiate these modes, and whether a 

vehicle even has an analogous state to 

‘‘on,’’ varies widely across EV models. 

For instance, some EVs, upon the door 

being opened, may activate some 

systems without providing electrical 

power to the motors, and may not be 

ready to be moved into a drive mode 

until another action is taken (such as 

depressing the brake pedal) which 

would typically entail the driver being 

seated. Others, however, may provide 

power to the motors upon the door 

being opened. Therefore, the agency 

attempted to incorporate language that 

approximates the following moment in 

a start-up sequence for an EV: an 

occupied outboard seat, ready to drive, 

but not yet in a drive mode. (This 

condition also closely approximates 

when the ignition of a conventional 

vehicle, certified to the option which 

uses the ignition switch ‘‘on’’ or ‘‘start’’ 

to indicate occupancy, is moved to the 

‘‘start’’ position). These requirements 

should equalize the safety benefits of 

the start-of-trip warning across vehicles 

with and without ignition switches. 

To accomplish this objective, we are 

adding language from FMVSS No. 305; 

‘‘Electric-powered vehicles: electrolyte 

spillage and electrical shock 

protection.’’ That standard defines 

‘‘possible active driving mode’’ as ‘‘the 

vehicle mode when application of 

pressure to the accelerator pedal (or 

activation of an equivalent control) or 

release of the brake system causes the 

electric power train to move the 

vehicle.’’ 177 As such, the mode is 

analogous to the vehicle being placed in 

a drive gear. Additionally, FMVSS No. 

305, S5.4.6.1 Indicator of possible active 

driving mode, states that ‘‘[a]t least a 

momentary indication shall be given to 

the driver each time the vehicle is first 

placed in possible active driving mode 

after manual activation of the 

propulsion system.’’ This language 

implies that ‘‘manual activation of the 

propulsion system’’ precedes the 

‘‘possible active driving mode.’’ In the 

final rule that added this language to 

FMVSS No. 305, we explained that the 

phrase ‘‘when the vehicle is first placed 

in possible active driving mode after 

manual activation of the propulsion 

system’’ was meant to indicate ‘‘start 

up.’’ 178 Thus, we believe that the 

appropriate time in the start-up 

sequence of an EV (which is roughly 

analogous to the movement of the 

ignition of a conventional vehicle to the 

‘‘start’’ position) is upon manual 

activation of the propulsion system, but 

prior to the vehicle being placed in 

‘‘possible active driving mode’’ as 

defined by FMVSS No. 305. We 

understand that the process of driving 

system activation could vary from 

vehicle to vehicle but believe that the 

criteria in the final rule encompass all 

or most EV start-up sequences.179


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vehicle, the warning will be delayed until the driver 

has entered the vehicle to comply with the 

occupancy requirement, even if such a vehicle is 

certified to the first option. 

180S7.3(c). These are the definitions for manual 

belts. For automatic belts, see supra n.18. 

181Section 2.46. 

182Section 2.46. 

2. Belt Use Criteria 

The current driver’s belt warning 

requirements specify that a belt is ‘‘not 

in use’’ when, at the option of the 

manufacturer, either the seat belt latch 

mechanism is not fastened or the belt is 

not extended at least 10.16 centimeters 

(cm) (4 inches (in)) from its stowed 

position.180

We proposed amending these current 

criteria by specifying criteria related 

only to the seat belt latch mechanism. 

Specifically, we proposed that a manual 

seat belt would be considered ‘‘not in 

use’’ when the seat belt latch 

mechanism is not fastened, and ‘‘in use’’ 

when the seat belt latch mechanism is 

fastened. We proposed eliminating the 

spool-out sensor requirements because 

we tentatively believed that 

accommodating the use of a spool-out 

sensor would not allow for an objective 

or reliable criterion for the proposed 

change-of-status warning. For instance, 

there may be instances where the 

webbing may not readily spool back in 

when the seat belt is unbuckled (e.g., 

due to the use of shoulder belt routing 

features or the use of a belt positioning 

booster seat), and thus would not 

reliably trigger the change-of-status 

warning. 

The proposal differed from ECE 

R16,181 which gives manufacturers the 

option of using either a belt latch or 

spool-out sensor.182 Euro NCAP does 

not specify webbing spool-out criteria, 

and only refers to the status of the belt 

buckle. The IIHS protocol does not 

specify such criteria. 

Comments 

We received one comment from Auto 

Innovators, which generally agreed with 

the agency’s proposal to enable 

compliance with the regulation through 

the use of seat belt latch sensors. Auto 

Innovators indicated that this proposal 

is consistent with ECE R16 and avoids 

introducing unnecessary complexity in 

redesigning rear belt reminder systems 

for the U.S. market. However, Auto 

Innovators requested that NHTSA 

update the definitions for S7.5 to ensure 

the regulation supports additional 

compliance options for classifying seat 

belt use, including systems that rely on 

camera-based sensors (or other 

advanced sensor technology). Auto 

Innovators commented that, currently, 

these options would not be permitted 

unless the belt use reminder system also 

included a belt latch mechanism. 

Agency Response 

In the NPRM we stated that the 

current FMVSS No. 208 belt use criteria 

for the driver’s seat belt warning 

requirements allow for the use of a belt 

latch or spool-out sensor, and that we 

were proposing to amend the belt use 

criteria to rely solely on the use of a belt 

latch sensor, and not provide 

requirements that would accommodate 

the use of a spool-out sensor. These 

statements were imprecise. The intent of 

the NPRM was not to restrict the types 

of technology manufacturers may use to 

determine whether or not an occupant 

is belted. The proposal was intended to 

identify objective criteria that NHTSA 

would use to determine whether or not 

a belt is in use. A manufacturer may use 

whatever technology it chooses to detect 

whether a belt is in use or not. However, 

regardless of the technology a 

manufacturer uses—whether it is a latch 

sensor or a camera—NHTSA, for the 

purposes of its compliance test, will 

consider a belt to be ‘‘not in use’’ when 

the belt latch is not fastened. Suppose, 

for example, that NHTSA tests a seating 

position equipped with a spool-out 

sensor for compliance with the changeof-status warning requirements. 

Suppose further that, in the test, a 

fastened belt is unfastened, but the 

spool-out sensor malfunctions so that 

the change-of-status warning does not 

activate. This would be considered an 

apparent test failure because the 

warning system did not activate when 

the status of the belt changed from in 

use to not in use (i.e., the belt latch 

became unfastened). 

3. Visual Warning Characteristics 

NHTSA proposed different 

requirements for the rear and front seat 

belt visual warnings. 

Rear Seat Belt Visual Warning 

We proposed that the visual warning 

be continuous or flashing and consist of 

icons or text and indicate how many or 

which rear seat belts are in use or not 

in use depending on the type of warning 

system. If icons are used to indicate how 

many or which rear belts are in use, we 

proposed that the icon(s) must be green; 

if icons are used to indicate to the driver 

how many or which belts are not in use, 

we proposed that the icon(s) be red. If 

text is used to indicate to the driver how 

many or which rear seat belts are in use 

or not in use, we proposed that the text 

contain the words ‘‘rear belt(s) in use’’ 

or ‘‘rear belt(s) not in use.’’ We also 

proposed to amend table 2 in FMVSS 

No. 101, ‘‘Controls and displays,’’ to 

clarify that the ‘‘Seat Belt Unfastened 

Telltale’’ depicted there does not apply 

to the rear seat belt reminder and to 

amend table 1 by adding in a row for the 

proposed rear seat belt warning. 

The requirement that the visual 

warning be continuous or flashing 

mirrors the current driver’s seat belt 

visual warning requirement and is also 

consistent with ECE R16. However, we 

proposed to depart from the current 

driver’s warning and from ECE R16 and 

standardize the color of the icons and 

text for the warnings to increase the 

likelihood that consumers would notice, 

recognize, and respond to the warnings. 

We believed that standardized colors 

and text will facilitate the interpretation 

of the signal. We departed from the 

current driver’s warning requirements 

and followed ECE R16 by not requiring 

specific icons because we believe the 

choice of icons would largely depend on 

whether the system displayed the 

number of seat belts in use or which 

seat belts are in use. 

Another difference between the 

proposal and ECE R16 was that ECE R16 

requires that the visual warning 

‘‘indicate at least all rear seating 

positions.’’ We understood this 

requirement to mean that the visual 

warning must depict all the rear seating 

positions. To give manufacturers design 

flexibility, we did not propose to require 

that the warning depict all rear seating 

positions. Instead, the proposed 

requirements would allow the visual 

warning to consist of text or icons 

indicating how many or which rear 

seats are fastened or unfastened. For 

example, the warning text might consist 

of ‘‘Middle and Right rear seat belts 

fastened.’’ Another visual warning 

option would be the seat belt icon with 

an adjacent numeral indicating the 

number of rear seat belts fastened. 

Accordingly, the proposal would allow, 

but not require, use of a pictogram. 

Front Seat Belt Visual Warning 

The current requirements for the 

driver telltale differ from those we 

proposed for the rear seat belts. As 

noted earlier in this document, some 

vehicles already equipped with a rear 

seat belt warning system in addition to 

a front seat belt warning system 

combine the two (such as with a 

pictogram depicting all seating 

positions). These vehicles also must 

continue to meet the current 

requirements for the driver seat belt 

telltale. These require that the warning 

be continuous or intermittent (flashing) 

and display either the identifying 

symbol or the words (‘‘Fasten Belts’’ or 

‘‘Fasten Seat belts’’) specified in table 2 

of FMVSS No. 101. Thus, vehicles that 


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currently have a rear seat belt warning 

system using a pictogram also provide a 

separate, FMVSS No. 101-compliant 

telltale for the driver’s seat belt warning. 

We proposed generally retaining, for 

both front outboard seats, the current 

visual warning requirement for the 

symbols or text specified in FMVSS No. 

101 because these visual warnings have 

been in place for decades and we 

believe that consumers are accustomed 

to them. Removing the requirement may 

have unintended negative effects if 

drivers and front passengers are not 

accustomed to new visual warnings or 

do not find the new visual warnings as 

effective. This means that if a 

manufacturer chose to use a pictogram 

format to comply with the new rear seat 

belt warning requirements, it could—as 

many manufacturers are already doing— 

include the front seat belts in this 

pictogram, but it would also have to 

provide the telltale specified in FMVSS 

No. 101, table 2. As we explained 

earlier, we proposed that the telltale for 

the front outboard passenger seat would 

also have to be visible to that passenger. 

We also proposed to require that for 

telltales associated with multiple front 

outboard seats, the seat with which each 

telltale is associated must be clearly 

recognizable to the driver and front 

outboard passenger. 

Comments 

Regarding the rear seat belt warning 

telltale, several commenters suggested 

that NHTSA should require visual 

warnings that indicated all rear seating 

positions. Consumer Reports 

encouraged NHTSA to align with ECE 

R16 by requiring that visual warnings 

indicate all rear seating positions. It 

argued that although a seating map may 

require a somewhat more sophisticated 

display, it is preferable because it offers 

the driver complete information while 

facing forward. Auto Innovators and 

HATCI commented that contextual 

displays or pictograms are generally 

feasible and useful. Auto Innovators 

also added that several automakers have 

already implemented seat belt warning 

systems that use a contextual display 

diagram to provide the driver with 

information on the status of passenger 

belt use. 

Some commenters such as HATCI and 

NADA also explicitly requested 

flexibility in telltale design. Rivian 

requested flexibility in choosing icons 

for the front and rear seat belt reminder 

warnings and that NHTSA not require 

the FMVSS No. 101 icon for the front 

seat belt reminder warning icon. HATCI 

supported providing manufacturers 

flexibility in the rear seat telltale and 

commented that the use of a pictogram 

for the rear seat belt warning will allow 

for more flexibility for different vehicles 

and vehicle sizes. Consumer Reports 

also commented that, within a seating 

map, easily recognizable icons are 

preferable to text, as icons enable a 

driver to assess seating usage at a quick 

glance, without having to read. 

Consumer Reports also argued that 

easily recognizable icons are also useful 

for drivers for whom English is not a 

first language. 

NSC commented that seat belt 

warning systems have different 

operational parameters, generic names, 

and limitations across manufacturers 

and sometimes even across the same 

manufacturer’s varying models. It urged 

NHTSA to consider standardizing 

generic nomenclature as well as 

standardizing warning and icon symbols 

to reduce driver confusion. 

Mercedes commented that, based on 

the requirements in the proposal, there 

would be technical challenges with 

providing the driver seat belt status 

information within the instrument 

cluster for seating configurations that 

can hold up to 13 rear passengers. 

Auto Innovators commented that in 

addition to issues related to the symbol, 

standardizing the text to say ‘‘Rear 

belt(s) in use’’ or ‘‘rear belt(s) not in 

use’’ may be difficult to package on the 

instrument cluster. Auto Innovators 

requested that the agency permit the use 

of either the word ‘‘Rear’’ or a 

corresponding number next to the seat 

belt icon referencing which seating 

position is unbuckled as an acceptable 

alternative. It noted that this request is 

similar to the number 2 notation used 

next to the air bag symbol for specifying 

the icon is relevant to the passenger-side 

air bag. 

Auto Innovators and Rivian supported 

harmonizing the telltale symbol with 

ECE R16. However, Auto Innovators, 

Mercedes, Honda, NADA, and HATCI 

requested that the agency also permit 

the use of a neutral color (e.g., gray) that 

could be used to display either an 

unoccupied seat or, for positive only 

systems, a seat that remained in the 

unbuckled condition. For negative only 

and full-status systems, the symbol 

would be required to be red to indicate 

occupancy in an unbelted condition. 

Auto Innovators commented that this 

approach is being widely adopted in the 

U.S. and other markets and is 

understood by consumers. Accordingly, 

Auto Innovators requested aligning the 

color requirements with ECE R16. 

Mercedes expressed concern that red 

icons should not be used if the buckle 

has not changed status because there is 

no critical information to be shared with 

the driver, and red could provide a false 

alarm and lead to desensitization if it is 

always on. Hyundai also noted that it is 

not aware of consumer complaints or 

requests to deactivate existing visual 

seat belt displays. 

Auto Innovators and Rivian argued 

that, given the prevalence of red-green 

color vision deficiency among the U.S. 

population, the requirement should not 

limit the ability of manufacturers to 

implement approaches that may be 

more easily understood or recognized by 

consumers. Auto Innovators indicated 

that the rule should include allowances 

for providing a visual diagram of all 

seating positions whereby belt use can 

either be communicated through the 

presence or absence of the belted 

symbol or through the use of a bi- or tricolor scheme consisting of green and 

red symbols to indicate belt status, and 

either gray or white symbols to denote 

either unoccupied seats (for systems 

with occupant detection) or unbelted 

seats (for systems without occupant 

detection) at the manufacturer’s 

discretion. 

Rivian and GM also noted that 

permitting the use of other icons, such 

as a checkmark to indicate belts in-use 

and a ‘‘x’’ to indicate belts not-in use for 

both front and rear occupants seat belt 

status, could help mitigate the 

challenges with red and green 

coloration if manufacturers were 

permitted flexibility in the use of 

different icons for both the front and 

rear locations. Rivian further 

commented that the agency proposed 

that the ‘‘Seat Belt Unfastened Telltale’’ 

requirement, depicted in table 2 in 

FMVSS 101, Controls and displays, does 

not apply to the rear seat belt reminder. 

Rivian stated that its interpretation of 

the proposal is that manufacturers may 

use other icons such as a checkmark to 

indicate belts in-use and a ‘‘x’’ to 

indicate belts not in use. Rivian 

recommended that for consistency and 

occupant recognition, NHTSA allow 

this design flexibility for the front and 

rear belt reminders. It stated that this 

commonality is particularly important 

for pictogram designs driven by other 

protocols, such as IIHS, and would help 

address the color issue. 

GM also indicated that glanceability 

can be significantly improved through 

redundancy, which involves combining 

both color and forms as cues. It cited 

several studies in support of this 

assertion. GM argued that the symbols, 

along with the colors of green 

representing success, red representing 

failure, and gray representing an empty 

seat, can ensure clear communication of 

the belt status to the customers. 

Honda commented requesting 

clarification on the proposed 


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requirement that for telltales associated 

with multiple front outboard seats, the 

seat with which each telltale is 

associated must be clearly recognizable 

to a driver and to any front outboard 

passenger. Honda indicated that it 

understands the final rule to require the 

telltale to use the identifying symbol or 

words specified in table 2 of FMVSS No. 

101 and to also allow the use of a single 

telltale to be associated with multiple 

front outboard seats. However, Honda 

suggested that the ‘‘clearly 

recognizable’’ language may be contrary 

to Honda’s understanding. Honda 

commented that it is not aware of any 

consumer concerns with distinguishing 

the front seat positions to which this 

single telltale is associated and believes 

that maintaining this standardized 

approach will facilitate continued 

consumer understanding. Honda also 

expressed concern about the cost 

burden if this requirement cannot be 

met with a single telltale and concern 

about the extra visual indicator 

overriding other warnings. Honda 

provided a list of telltale designs and 

requested clarity regarding whether they 

would meet the ‘‘clearly recognizable’’ 

language. Honda also requested that the 

rule allow for a single telltale to display 

all seating positions. 

Agency Response 

NHTSA generally agrees with the 

commenters who recommended that the 

rule provide manufacturers flexibility, 

but we do believe that some 

standardization of the visual warning 

would provide safety benefits. We note 

that while many of the requirements 

discussed below apply only to the rear 

seat belt warning, manufacturers may 

choose to integrate the warnings for the 

front and rear, so we are presenting this 

material together. 

Requirements for the Rear Seat Belt 

Visual Warning 

We disagreed with Consumer Reports 

and have decided to depart from ECE 

R16 and not require that all rear seating 

positions be depicted. While such a 

requirement would provide the driver 

with more information, we have 

decided to give manufacturers design 

flexibility (such as by using text, 

number of seats buckled/unbuckled, 

etc.) so that they can decide how to 

optimize design for each particular 

vehicle. 

One situation in which this flexibility 

would be particularly important is for 

buses and vans with many rear seats. As 

we explain above (see Section VI.A.1, 

Applicability) one difference between 

the final rule and ECE R16 is that the 

final rule applies to small buses such as 

15-passenger vans, while the ECE R16 

rear seat belt warning requirements do 

not apply to vehicles with more than 9 

seats (including the driver). As we 

acknowledged in the NPRM, vehicles 

with a larger number of rear seats, such 

as passenger vans and buses, may 

encounter visual signal complexities; 

not dictating specific types of signals 

should provide manufacturers with 

adequate flexibility to address these 

types of issues. We believe these 

vehicles, in particular, would benefit 

from the option to indicate how many 

rear seats are fastened; for example, a 

visual warning option for vehicles with 

multiple rows would be the seat belt 

icon with an adjacent numeral 

indicating the number of rear seat belts 

fastened. We recognize that such a 

requirement would require more space 

if a manufacturer decides to display a 

warning with multiple rear rows and 

may entail redesign of the instrument 

panel or display space. We note that 

while one commenter (InterMotive) 

indicated that it has an aftermarket 

solution for a rear warning system for 

such higher-occupancy vehicles, 

NHTSA is not aware of any new 

vehicles equipped with such systems. In 

light of the current state of the market, 

we are providing two years of lead time 

and have attempted to specify the final 

requirements in such a way as to 

provide manufacturers as much 

flexibility as possible so that they can 

devise solutions for their specific 

vehicles. 

Similarly, with respect to the visual 

warning for the rear seat belts, we have 

decided to finalize the proposal and 

permit both icons (symbols) and text. 

However, we are modifying the proposal 

and not specifying standardized text. 

We are also clarifying that numbers may 

also be used in addition to symbols, and 

are finalizing the proposal to 

standardize colors for symbols (and 

numbers). While we recognize that 

standardized icons would help drivers 

recognize the icon when driving 

different (multiple) vehicles, we believe 

there are even greater benefits to 

providing manufacturers with 

flexibility; manufacturers can optimize 

the visual warning based on the vehicle 

design and consumer preferences, 

particularly since there are a range of 

different approaches being used already. 

(Icons appear to be prevalent in newer 

vehicles.) We have also decided to allow 

the use of text and/or numbers other 

than what we proposed for the rear seat 

belt warning to afford manufacturers as 

much flexibility as possible. We note 

that the effectiveness of numbers 

depends on how well the design is 

executed; for example, one commenter 

provided an example showing that it 

can be confusing. Accordingly, 

manufacturers should not assume 

drivers will be familiar with seat 

numbers when developing their 

warning. On the other hand, as 

discussed below, we are standardizing 

colors to facilitate the interpretation of 

the signal. 

We have decided to finalize the 

requirements for the color of symbols or 

numbers if used to indicate how many 

or which rear seat belts are (not) in use. 

After considering the comments, 

NHTSA concludes that the advantages 

of standardizing colors outweigh the 

drawbacks. We believe that 

standardizing colors limits confusion 

and allows for faster interpretation. We 

note that the FMVSS generally do not 

address color blindness. Importantly, 

however, this requirement does not 

prevent manufacturers from designing 

the visual warning so that it can be 

perceived by colorblind consumers. For 

example, OEMs could design systems 

using a combination of color and a 

positive/negative symbol. Moreover, we 

agree with GM that such redundancy 

can aid in rapid interpretation of the 

warning (glanceability). Use of a symbol 

without a color would be prohibited but 

we believe this requirement is 

warranted because use of a color would 

aid in faster identification of buckled/ 

unbuckled seats for most users. 

Similarly, the final rule provides that 

the change-of-status visual warning may 

use the same telltale as the start of trip 

warning, provided that the color of an 

illuminated symbol or number used to 

indicate to the driver how many or 

which rear seat belts experienced a 

change of status from in use to not in 

use is red. 

NHTSA is, however, clarifying that 

the proposed requirements were not 

intended to prohibit the use of gray or 

other neutral colors or signifiers (such 

as a non-illuminated indicator) to 

denote seats that are unoccupied or to 

denote a seating position for which 

information about buckle status is not 

being conveyed (e.g., using gray to 

indicate seating positions at which the 

belt is fastened in a negative-only 

system that does not use occupant 

detection). This approach is being 

widely adopted in the U.S. and other 

markets and, in our view, is understood 

by consumers. To more clearly convey 

our intent here, the final rule explicitly 

provides that a visual warning is not 

required for (1) an unoccupied seat if 

the system is able to determine whether 

or not a seat is occupied; (2) a seat belt 

that is in use in a system designed to 

indicate to the driver how many or 


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183Section 8.4.3.2. 

184 It is possible to design single telltales that 

comply both with FMVSS No. 101, Table 2 and the 

requirement that for telltales associated with 

multiple front outboard seats, the seat with which 

each telltale is associated must be clearly identified 

because FMVSS No. 101 allows supplemental 

symbols and information. See S5.2.3 

(‘‘Supplementary symbols, words, or abbreviations 

may be used at the manufacturer’s discretion in 

conjunction with any symbol, word, or abbreviation 

specified in Table 1 or Table 2.’’). 

185We note that the proposed ‘‘clearly 

recognizable’’ language was identical to language 

currently found in S19.2.2 of FMVSS 208. That 

language was added to the standard in a 2022 final 

rule on Occupant Protection for Vehicles with 

Automated Driving Systems. In the preamble to that 

final rule, we explained that that provision would 

not permit a single telltale for both front outboard 

seating positions: ‘‘[t]he Alliance and GM requested 

allowing a single telltale for both front outboard 

seating positions. It is NHTSA’s position that, while 

a single telltale unit that distinguishes both 

indicators would be acceptable, a single light 

indicating the suppression status of both air bag 

systems, but not distinguishing their individual 

state of suppression would not. Separate 

suppression telltales clarify which associated 

seating position is suppressed, allowing the 

corresponding passenger to respond to the 

information with appropriate action.’’ 87 FR 18560. 

While NHTSA continues to believe that requiring 

separate telltales for two front seating positions was 

justified for the reasons given in that rulemaking, 

after considering the comments, we believe that it 

would be appropriate for this final rule to allow a 

single telltale for two seating positions, as long as 

the visual warning clearly identifies the seating 

position(s) for which the warning is intended. 

186 88 FR 61674 61742–43 (Sept. 7, 2023) 

(proposed front and rear warnings at S7.5(b)(5) and 

S7.5(c)(5), respectively). Proposed S7.5(c)(1)(v), 

which also required that the rear seat belt visual 

warning not be overridden, was redundant. This 

issue is discussed later in this document. 

187 49 CFR 571.101, S5.5.5. See also S5.5.2 (‘‘The 

telltales for any brake system malfunction required 

by Table 1 to be red, air bag malfunction, low tire 

pressure, electronic stability control malfunction (as 

of September 1, 2011), passenger air bag off, high 

beam, turn signal, and seat belt must not be shown 

in the same common space.’’) 

which rear seat belts are not in use; and 

(3) a seat belt that is not in use in a 

system designed to indicate to the driver 

how many or which rear seat belts are 

in use. Therefore, the color 

requirements will not apply to symbols 

or numbers that are conveying any of 

these three types of information, 

because such information is not 

considered part of the required warning. 

Requirements for the Front Outboard 

Seat Belt Visual Warning 

We have decided to finalize the 

proposal to maintain the FMVSS No. 

101 icon for the driver’s seat belt 

warning and extend it to the front 

outboard passenger seat belt warning. 

We continue to believe, as we explained 

in the NPRM, that this requirement is 

beneficial because these visual warnings 

have been in place for decades and we 

believe that consumers are accustomed 

to them. It is also in line with ECE R16, 

which requires the same icon for the 

front seats.183 At this time we therefore 

do not see a need to remove this 

requirement. 

As stated in Section VI.B.4, in 

response to the comments, NHTSA has 

modified the proposal so that the final 

rule requires that the front outboard 

passenger visible warning be visible 

only to the driver, except for two 

potential future situations where only 

requiring the visual warning to be 

visible to the driver would not be 

sufficient. The first is for dual-mode 

ADS-equipped vehicles that still have a 

driver’s seat and driving controls. For 

such vehicles the driver’s seat could 

remain unoccupied throughout the 

vehicle’s operation. In this situation, 

limiting the visibility of the front seat 

warnings to the driver’s seat would 

result in the passenger not seeing the 

warning. The second is for ADSequipped vehicles without a driver’s 

designated seating position. For the 

first, the final rule requires that the 

visual warning for the front outboard 

passenger seat belt must be visible from 

the front outboard passenger seat, and 

for the second the final rule requires 

that the visual warning for each 

outboard designated seating position be 

visible from each outboard passenger 

seating position. 

Accordingly, while we proposed that 

for telltales associated with multiple 

front outboard seats the seat with which 

each telltale is associated must be 

clearly recognizable to a driver and to 

‘‘any front outboard passenger,’’ the 

final rule instead requires that a visual 

warning associated with multiple front 

outboard seats must ‘‘clearly identify 

the seating positions for which the 

warnings are intended.’’ Honda’s 

comment concerned the proposed 

‘‘clearly recognizable’’ language. 

NHTSA clarifies that this final rule does 

not require a separate telltale (i.e., a 

telltale with the identifying symbol 

specified in table 2 of FMVSS No. 101) 

for each front seating position nor does 

it require any particular visual warning 

design. We believe that one telltale 

which distinguishes which position is 

unbuckled would be acceptable, as 

would separate telltales, as long as the 

visual warning clearly identifies the 

seating position(s) for which the 

warning(s) is intended. We leave it to 

manufacturers to design their systems 

such that they can certify in good faith 

that they meet the standard, and the 

final rule does not further specify how 

to do so to preserve that design 

flexibility.184 185

4. Interaction With Other Vehicle 

Warnings 

NHTSA proposed that neither the 

visual nor the audible component of the 

seat belt warning for the both the front 

and rear seat belts could be overridden 

by other warnings for the required 

durations.186 This proposal was 

consistent with the current 

requirements in FMVSS No. 101 for the 

driver’s seat belt telltale which specify, 

among other things, that the seat belt 

telltale must displace any other symbol 

or message in that common space while 

the underlying condition for the 

telltale’s activation exists.187 We did not 

believe that the seat belt warning 

requirements would interfere with 

warnings for other safety systems 

because we believed that those other 

warnings have dedicated warning 

signals, and that manufacturers would 

have enough flexibility to determine the 

best way to implement the various 

warnings. For instance, warnings for 

another potential safety risk may be 

more aggressive than those for the seat 

belts. With regard to available space, we 

proposed that the visual signal might be 

displayed as a telltale on the instrument 

panel or on the vehicle’s information 

display screen. We noted that 

manufacturers would also have to 

determine whether the driver and rear 

passenger seat belt visual warning 

would be treated the same. Neither ECE 

R16 nor Euro NCAP address interaction 

with other vehicle warnings. 

Comments 

A number of commenters expressed 

concern about the proposed requirement 

that the visual warning could not be 

overridden. HATCI, for example, 

commented that if manufacturers 

display the rear telltale in the visual 

information screen, they would display 

the rear seat pictogram in the same 

location often used to display advanced 

safety feature warnings such as Forward 

Collision Warning (FCW) or Automatic 

Emergency Braking (AEB) and may 

impede or prevent those warnings. Auto 

Innovators commented that several 

automakers currently have warning 

systems that use a contextual display 

diagram to provide the driver with 

information on the status of passenger 

belt use. However, they noted that these 

displays can be relatively large and 

necessitate sharing limited display 

space in the instrument panel, and 

therefore may need to be temporarily 

overridden to convey other safety urgent 

warnings. 

To address this concern, Auto 

Innovators, NADA, Nissan, Rivian, 

Honda, and HATCI requested that 

NHTSA remove the proposed override 

requirements, or provide a general 


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188The final rule does not prohibit manufacturers 

from designing vehicles so that a crash-imminent 

visual warning, or other visual warning that alerts 

the driver to take some immediate action, is more 

prominent than the seat belt warning. 

189With respect to InterMotive’s comment, its 

aftermarket product has a separate display, so it is 

not relevant to this discussion. 

exception that manufacturers have 

discretion to prioritize other safety 

relevant warnings as needed. Auto 

Innovators commented that NHTSA 

should harmonize with ECE R16 and 

remove the override requirements for 

both front and rear row seating positions 

to provide flexibility for manufacturers 

to implement in-vehicle displays such 

that important information can 

temporarily override the reminder alert 

on an as-needed basis. 

Specific to the front reminder, HATCI 

recommended allowing a warning 

displayed in the vehicle’s information 

display screen to be temporarily 

suppressed when it is necessary to alert 

or redirect the driver’s attention to an 

advanced safety warning related to 

vehicle operation. On the other hand, 

Honda commented that the front seat 

belt unfastened telltale, as currently 

specified in FMVSS 101, should remain 

a dedicated warning that cannot be 

interrupted. 

Auto Innovators supported providing 

manufacturers with the flexibility to 

prioritize safety alerts for the duration 

that other safety critical warnings may 

be required. Honda and Mercedes 

commented that it is not essential for 

the rear seat belt visual warning to be 

provided uninterrupted 100 percent of 

the time because it is supplemental to 

the audible warning. Because of this 

redundancy, in Auto Innovators’ view, 

other critical information should be 

allowed to be presented to the driver. 

Honda and Auto Innovators urged 

NHTSA to allow visual warnings, with 

the exception of the dedicated telltale 

currently specified in table 2 of FMVSS 

No. 101, to be temporarily overridden 

by system failure warnings and 

warnings requiring an urgent response. 

Honda stated that doing so would allow 

existing high-visibility display locations 

to convey the most urgent warning to 

the driver, while retaining a baseline 

warning that would convey whether 

there is an unbelted occupant. Honda 

and Auto Innovators argued that this 

approach would also align with the 

current FMVSS No. 101 requirements 

prescribed in section 5.5 where the seat 

belt unfastened symbol or text (‘‘Fasten 

Seat Belts’’) must have a dedicated 

telltale, but other supplemental 

warnings may be displayed in a 

common display space. Auto Innovators 

requested additional clarification on the 

applicability of the override prohibition 

and whether it applies to suppression of 

the visual warning, audible warning, or 

both. It requested that both be able to be 

overridden. 

Honda and Auto Innovators also 

commented that the proposal would 

necessitate several changes to systems 

currently deployed without any 

substantiated benefit. First, Honda 

explained that the visible display space 

for the driver, particularly the 

instrument cluster, is already allocated. 

Therefore, the proposal would require 

either the implementation of a new 

standalone indicator, dedicated to only 

the rear seating positions, or 

repositioning the warning to a less ideal 

area of the instrument cluster. Honda 

indicated an example in which it may 

become necessary to minimize the seat 

belt warning size in order for the 

warning to have a dedicated space. 

Honda and Auto Innovators argued that 

these changes would require substantial 

redevelopment and that implementing 

such a system within the proposed time 

frame would be impractical. 

Rivian commented that the proposal 

does not contain volume or tone 

requirements for the chime. Rivian 

inquired about whether a change in 

volume for the audible chimes during 

the required duration of the warning to 

increase the volume of a competing 

safety-critical warning would or would 

not constitute an override. 

Finally, InterMotive commented that 

the proposed requirements should not 

create interaction issues between 

different vehicle systems. InterMotive 

noted that it has a product in the market 

that would comply with the proposed 

requirements and that there have been 

no issues with the product interacting 

with other warning systems. 

Agency Response 

NHTSA has decided to finalize the 

proposal that the visual seat belt 

warning not be overridden by other 

vehicle warnings. However, in response 

to the comments we have decided to 

modify the proposal and permit the 

audible component of the front and rear 

seat belt warnings to be overridden by 

certain safety-critical warnings that 

require the driver to take some 

immediate action. 

Visual Warning 

We are finalizing the proposal that the 

visual seat belt warnings not be 

overridden by other vehicle warnings. 

FMVSS No. 101 has long required that 

the driver’s seat belt visual warning not 

be displaced by other warnings. We do 

not believe that these amendments to 

the seat belt warning requirements 

should lead us to alter this 

requirement.188 There are several 

reasons for this conclusion. 

First, while the final rule requires an 

additional telltale for the rear seat belt 

warning, we believe that there is 

sufficient room on the vehicle’s 

instrument panel or on the vehicle’s 

information display screen. Most safety 

telltales have a dedicated icon and 

display space. In particular, we believe 

most critical safety warnings have 

dedicated space for their respective 

icons/symbols. NHTSA’s understanding 

of contemporary vehicle designs is that 

they are more likely to feature a larger 

combined display instead of separate 

instrument panels and center stack 

displays, so there should be sufficient 

space to present two simultaneous 

visual warning signals separately. 

Whether prohibiting override of the seat 

belt warning would require redesign of 

the display area depends on whether the 

competing warnings are supplemental. 

If they are, then not allowing the seat 

belt warning to be overridden would not 

necessarily require redesign; while the 

supplemental warning could not be 

displayed in the space common to the 

seat belt warning, the primary warning 

could still be displayed. However, if the 

competing warning were not simply 

supplemental, then we acknowledge 

that redesign would be necessary. If an 

OEM chose to redesign in such a way as 

to have dedicated space for all the 

different warnings, we believe it would 

be possible, but acknowledge it might be 

burdensome. However, we believe the 

final rule provides manufacturers with 

ample flexibility in terms of what types 

of warnings are allowed and not 

dictating a specific location for the 

warning.189

Second, it would likely be rare for the 

seat belt warning and other warnings to 

occur at the same time. With respect to 

the front seat belt warning, because 

these systems have been in place for 

decades, and because FMVSS No. 101 

has long required that the driver’s seat 

belt visual warning not be displaced by 

other warnings, we believe these visual 

warnings have their dedicated display 

space already and thus do not warrant 

allowing override for other safety 

critical warnings because the warnings 

can activate simultaneously. With 

respect to the rear seat belt start-of-trip 

warning, given the relatively short 

duration (30 seconds) and timing 

(ignition on or start), it should be 

relatively unlikely for another safetycritical warning to be necessary in that 

time. With respect to the rear seat belt 

change-of-status warning, because we 

are requiring that the start-of-trip visual 


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190See 88 FR 61674, 61742 (Sept. 7, 2023) 

(Proposed S7.5(b)(5) and S7.5(c)(5)). 

191See 88 FR at pg. 61743 (Proposed S7.5(c)(v)). 

192 Kidd, D.G. (2012). Response of part-time belt 

users to enhanced seat belt reminder systems of 

different duty cycles and duration. Transportation 

Research Part F, 15, 525–534. 

warning not be overridden, we believe 

that although a safety critical warning 

may need to activate at the same time 

as the change-of-status warning, the 

warnings will have been designed to not 

be in the same space and they can both 

activate simultaneously. 

Third, extinguishing the seat belt 

reminder visual warning during other 

warnings might confuse drivers. If they 

notice that the warning deactivates and 

then re-activates with no corresponding 

change in seat belt status, they may 

believe the system is malfunctioning. 

We are also declining to adopt 

Honda’s suggestion to allow override of 

the larger warning and rely on the use 

of the single FMVSS No. 101 front seat 

belt warning telltale for all seats. We 

believe that this would confuse the 

driver, because the driver would not 

know what seat the warning applies to. 

The current FMVSS No. 101 seat belt 

warning requirements apply only to the 

driver’s seat belt warning (with this 

final rule extending them to the front 

outboard passenger’s seat and the rear 

seats), and not to other seating 

positions. 

Audible Warning 

The final rule, however, does permit 

the audible component of the seat belt 

warnings to be overridden by certain 

safety-critical warnings that require the 

driver to take an immediate action. As 

an initial matter, we clarify that the 

proposal would have prohibited the 

audible component of the reminder 

from being overridden as well as the 

visual component.190 The proposed 

regulatory text contained a redundant 

provision that required that the rear seat 

belt visual warning not be overridden by 

other visual warnings that was likely the 

source of confusion.191 However, in 

response to the comments, NHTSA has 

decided to permit the seat belt audible 

warning to be overridden by certain 

warnings. Specifically, NHTSA believes 

it is reasonable to allow a pause in the 

audible seat belt warning to allow for a 

safety critical warning that requires the 

driver to take some immediate action. 

This includes crash avoidance warnings 

that require immediate action by the 

driver, such as braking or steering. With 

respect to Rivian’s comment, a change 

in volume of the chime would not 

constitute an override of the warning 

because the final rule does not regulate 

audible warning volume. See Section 

VI.C.5, Audible Warning Characteristics. 

5. Audible Warning Characteristics 

(Other Than Duration) 

The NPRM proposed a variety of 

specifications for the audible warnings. 

The proposed requirements were 

different for the front and rear audible 

warnings. 

For the rear change-of-status warning 

(which had a minimum required 

duration of 30 seconds), we proposed 

that the audible signal could be 

intermittent or continuous and that if 

intermittent, inactive periods longer 

than 3 seconds would not be counted 

toward the total duration of the audible 

warning. We did not propose to specify 

minimum duty cycle, chime frequency, 

or warning cycle. 

For the front seat belt audible 

component of the start-of-trip and 

change-of-status warnings, we proposed 

more detailed requirements than for the 

rear seat belt audible warning because 

the minimum duration was much longer 

(essentially until all front outboard 

occupants were belted, for both the 

start-of-trip and change-of-status 

warnings). We proposed that the front 

seat belt audible warning may be 

continuous or intermittent. If 

intermittent, we proposed that, when 

active, the audible warning must be 

continuous or have a chime frequency 

of at least 0.5 Hz and a duty cycle of at 

least 0.2. The proposal defined, for an 

intermittent audible warning, the terms 

warning cycle, chime frequency, and 

duty cycle. The proposal defined 

‘‘warning cycle’’ as consisting of 

period(s) when the warning is active at 

the chime frequency or continuously, 

and inactive period(s). A warning cycle 

would begin with an active period and 

would be 30 seconds in duration. 

‘‘Chime Frequency’’ meant the 

repetition rate for an intermittent 

audible warning when the warning is 

active. ‘‘Duty Cycle’’ meant the total 

amount of time an intermittent audible 

warning is active during a warning cycle 

at the chime frequency or continuously, 

divided by the total warning cycle 

duration (30 seconds). These 

requirements were largely based on the 

results of a 2012 IIHS study on duty 

cycles.192 IIHS test protocols do not 

specify a duty cycle. We proposed that 

the same audible warning may be used 

for all seats. We did not propose a limit 

on the maximum duration of audible 

gaps for the purposes of determining the 

warning’s total duration because we did 

not propose a finite minimum duration. 

These proposals deviated from Euro 

NCAP and ECE R16’s specifications in 

some ways. Euro NCAP specifies that 

for the front seats the audible signal 

must not have gaps greater than 10 

seconds, and that gaps longer than 3 

seconds would not count toward the 

warning’s total duration. The final 

audible signal must be ‘‘loud and clear’’ 

for the driver. The 10 second limit, in 

addition to its specification of a 3 

second gap limit toward the calculation 

of the warning’s total duration, would 

not be sufficient to ensure a 0.20 duty 

cycle warning. ECE R16 also does not 

count warning gaps longer than 3 

seconds toward the required minimum 

warning duration requirement. 

Comments 

Auto Innovators and NADA requested 

that NHTSA harmonize with ECE R16, 

which provides increased flexibility for 

manufacturers determining the 

characteristics of both front and rear 

row belt reminder alerts. 

Auto Innovators recommended that 

the agency avoid defining 

characteristics (such as the warning and 

duty cycles) that would prevent a 

manufacturer from implementing 

different alerts such as escalating alerts. 

Mercedes commented that its current 

seat belt reminder system design starts 

a baseline alert once the criteria have 

been met; if the conditions of the seat 

belts at the occupied seats have not 

changed after 30 seconds, the system 

will escalate the warning. Mercedes 

stated that this approach does not cause 

excessive annoyance to drivers and does 

not negatively affect the efficacy of the 

warning system. Mercedes urged 

NHTSA to remove the continuous series 

requirement for manufacturers to 

develop systems with effective 

escalating alerts. Consumer Reports also 

commented that audible warnings 

should escalate. 

Honda sought clarity on the ‘‘warning 

cycle’’ requirements as proposed. 

Additionally, it encouraged the agency 

to consider whether adopting a warning 

that is continuously active (i.e., 100 

percent duty cycle) for a definite 

duration of 90 seconds would be as 

effective as the proposal to require an 

indefinite warning with a minimum 

duty cycle of 20 percent. Honda 

explained that its experience is that a 

continuous 90-second chime is 

sufficiently persistent and might offer 

greater effectiveness compared to an 

indefinite warning that delivers only a 

6-second chime followed by a 24-second 

pause between chimes. IIHS, identifying 

the same concern, urged NHTSA to 

require auditory signals to be separated 

by no more than 3 seconds in addition 


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193 Id. 

194This was calculated as follows: (0.2 = 0.75/(3 

+ 0.75) (duty cycle is the total amount of time an 

intermittent audible warning is active (.75 seconds) 

divided by the total warning cycle duration (time 

active plus the duration of the gap)). 

to requiring a minimum 20 percent duty 

cycle. 

IIHS, supported by MADD, Advocates 

and Public Citizen, and the National 

Association of Mutual Insurance 

Companies (NAMIC), requested that 

NHTSA set minimum requirements for 

the volume and fundamental frequency 

of an auditory reminder to ensure it is 

‘‘loud and clear’’ and will be noticed by 

vehicle occupants. IIHS provided 

supporting materials for the volume and 

fundamental frequency minimums that 

it requires. It also commented that 

NHTSA should require the same 

auditory reminder characteristics (e.g., 

volume, fundamental frequency, gap 

between signals, duty cycle) for the 

front and rear rows. It stated that 

consistency makes the requirements 

easier to implement for automakers, 

easier for consumers to understand, and 

would align with current practice. 

Agency Response 

After reviewing comments, we are 

finalizing the proposed audible warning 

requirements for both the front and the 

rear warnings with minor changes. The 

first change is that the front start-of-trip 

warning now must meet only the same 

minimum requirements as the rear 

change-of-status warning, because both 

are time-defined. The second change is 

that we are adding a 10-second 

maximum gap limitation, similar to 

Euro NCAP, to both of these warnings. 

Because this final rule requires that gaps 

longer than 3 seconds do not count 

toward the required duration for these 

two warnings, without a maximum gap 

limitation there would be no limit on 

the amount of time it would take for the 

warning to reach the 30 second 

minimum cumulative warning duration. 

Allowing audible warnings that take too 

long to meet the 30 second minimum 

cumulative warning duration could 

degrade the effectiveness of the 

warning. We also believe that this 

requirement will not impede the 

manufacturer’s design flexibility 

significantly and that these parameters 

meet the need for safety, are objective, 

and are practicable, because they 

provide an acceptable minimum level of 

effectiveness while allowing 

manufacturers latitude to optimize the 

warning for effectiveness and vehicle 

occupant acceptance. We continue to 

believe that the parameters stated for the 

front second phase warning—warning 

cycle, duty cycle, and chime 

frequency—are essential for an 

indefinite warning to meet the need for 

safety. Similarly, we believe that the 30- 

second front start-of trip-warning and 

rear change-of-status warning will be 

effective with the specified signal gap 

limitations. 

We have concluded that specifying 

minimum requirements for chime 

frequency and duty cycle for the second 

phase front audible warning is critical 

for ensuring a minimum baseline of 

effectiveness. This approach is based on 

the existing research which suggests 

that warning signal characteristics— 

such as duty cycle, frequency, volume, 

or timbre—can be adjusted to balance 

effectiveness and consumer acceptance 

but also shows that there is a minimum 

level of effectiveness provided by 

requiring a 30-second repeating warning 

cycle, with a minimum 0.5 Hz chime 

frequency and a 20 percent duty 

cycle.193 Because ECE R16 requires very 

short time-defined alerts for the front 

seat belt warning (30 seconds), a duty 

cycle requirement is not necessary. We 

are incorporating a duty cycle 

requirement because in the context of an 

indefinite warning this requirement 

ensures a minimum time that the 

audible warning chime will be active. 

Additionally, we are not incorporating 

one of the approaches taken by ECE R16 

and Euro NCAP to limit gaps in the 

audible warning (that gaps longer than 

3 seconds would not count toward the 

warning’s total duration) because we do 

not have research suggesting that it 

would increase effectiveness. 

Additionally, a sole requirement that 

gaps longer than 3 seconds would not 

count toward the warning’s total 

duration would be inadequate in the 

context of an indefinite warning. 

Therefore, at this time, the agency is 

making the judgement that specifying a 

maximum signal gap of 3 seconds, 

either with or without a duty cycle, 

unnecessarily limits manufacturer’s 

flexibility for the speed-initiated 

warning. Finally, this final rule does not 

prevent the design of escalating alerts, 

as some manufacturers such as 

Mercedes suggested in their comments. 

The duty cycle and chime frequency are 

minimum requirements, and the 

warning cycle specification does not 

require each cycle to be identical. 

Manufacturers may design escalating 

alerts within the minimum 

requirements of this final rule. 

Additionally, given the required duty 

cycle for the front indefinite warning, 

we do not need to incorporate a 

maximum signal gap (i.e., no gaps 

longer than 10 seconds) like the one 

used by Euro NCAP. Some comments 

suggested that the proposal contained a 

flaw: that given the 20 percent duty 

cycle and 30 second warning cycle 

requirements, this rule would allow a 

warning that was active for 6 seconds, 

with a 24-second gap. However, this 

was not an error. Commenters did not 

demonstrate that the proposed warning 

would be ineffective, and that notion is 

inconsistent with available data. 

Increasing the duty cycle would, after a 

point, cause a reduction in signal gaps, 

even if no specific signal gap limitation 

were required. Therefore, if those 

commenters were correct, and the gap in 

the signal were a meaningful 

characteristic, we would expect higher 

duty cycles to increase effectiveness. 

However, the 2012 IIHS study on duty 

cycles, referenced in the NPRM, 

indicated that there was not a 

statistically significant difference in 

effectiveness between the 20 percent, 50 

percent, and 100 percent duty cycles, 

which cycled over 30 second warning 

periods. This suggests that beyond the 

maximum gap established by a 20 

percent duty cycle, reducing the gap 

does not increase effectiveness. Without 

demonstrable safety benefits, such a 

limit would unnecessarily restrict 

manufacturers’ design flexibility. 

Therefore, we are not specifying a 

maximum signal gap in this final rule 

for the front seat belt indefinite warning. 

Only the time-defined front start-of-trip 

warning and the rear change-of-status 

warning have a signal gap rule (that 

gaps longer than 3 seconds would not 

count toward the warning’s total 

duration) and maximum signal gap 

requirement (10 seconds). Importantly, 

meeting the requirements of this rule 

does not preclude designing an alert 

that complies with the signal gap rules 

in ECE R16. As an example, with a 20 

percent duty cycle requirement and a 

gap duration of 3 seconds, a compliant 

alert could be active for at least 0.75 

seconds regardless of the chime 

frequency.194

With regard to requests to harmonize 

the requirements for the front and rear 

audible alerts, we do not believe it is 

necessary to require that the alerts have 

the same minimum characteristics 

across seating positions. Instead, we 

structured this final rule so that 

manufacturers, if they choose, may 

design one audible alert that complies 

with the requirements for both the front 

and rear alerts. We also continue to 

believe that given the short duration of 

the rear change-of-status warning, it is 

not necessary to specify characteristics 

such as duty cycle, chime frequency, 

and warning cycle. As we stated in the 


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195Accordingly, we explain in Section VI.C.4, 

Interaction with other vehicle warnings, that a 

change in the volume of the audible warning would 

not constitute an override of the warning. 196 88 FR 61674, 61704 (Sept. 7, 2023). 

NPRM, we believe establishing 

minimums for these characteristics is 

primarily needed for longer or indefinite 

alerts to ensure that the warnings have 

at least a minimum level of persistence. 

As such, since we have revised the 

requirements for the front seats so that 

the start-of-trip warning is required only 

to be at least 30 seconds long, we have 

decided that the audible portion of the 

start-of-trip warning should be subject 

to the same characteristics as the rear 

change-of-status warning. Therefore, as 

mentioned above, for consistency we are 

finalizing for both the front start-of-trip 

warning and the rear change-of-status 

warning only that inactive periods 

longer than 3 seconds would not be 

counted toward the total duration of the 

audible warning and that there be no 

gaps in the warning greater than 10 

seconds. The proposed minimum 

characteristics for the audible 

component of the front seat belt 

warning, as finalized, will now only 

apply to the audible front seat second 

phase warning. 

Finally, we are not incorporating the 

specifications for volume and frequency 

IIHS suggested. We have designed the 

final requirements to give manufacturer 

the flexibility to design warnings that 

are both effective and acceptable to 

consumers. We believe that sound 

volume and frequency can be used by 

manufacturers to make their warnings 

more effective and/or more acceptable, 

which is particularly important for an 

indefinite warning. Similarly, we are 

skeptical that a volume specification is 

needed because it has never been 

needed in the past. Since the early 

1970s, FMVSS No. 208 has required an 

audible driver’s seat belt warning with 

no additional audible warning 

requirements and manufacturers have 

been designing and implementing 

warnings under that structure without 

issue. Additionally, regarding 

frequency, IIHS indicated that nearly all 

systems tested already meet their 

suggested specification, so a regulatory 

requirement may not be needed. 

Nonetheless, as the new requirements 

are implemented, the agency will 

monitor these characteristics and assess 

whether additional rulemaking action is 

warranted.195

6. Warning Deactivation and 

Acknowledgement and Hardening 

In the NPRM, we proposed not to 

allow features which would permit the 

driver to acknowledge the warning and 

cancel it before the end of the required 

duration or to deactivate the warning for 

an entire trip or for a specified time 

period (thus preventing it from 

activating in the first place).196 We also 

did not propose requiring features to 

harden the system against 

circumvention due to concerns about 

the cost and effectiveness of such 

features. We sought comment on both 

issues and whether these features would 

impact the effectiveness of the rule. 

ECE R16 allows both short-term and 

long-term deactivation of the audible 

warning (with a variety of restrictions, 

such as that it be more difficult to 

effectuate a short-term deactivation than 

to buckle the belt). Euro NCAP does not 

provide any specifications for 

deactivation or acknowledgement of the 

warnings for the front seats; it allows 

acknowledgement only of warnings for 

rear seats, except for change-of-status 

warnings. Neither ECE R16 nor Euro 

NCAP requires hardening features. 

Comments 

Some commenters suggested making 

the visual warning, audible warning, or 

both dismissible, and presented a 

variety of approaches. For example, 

Auto Innovators and HATCI suggested 

harmonization with IIHS and ECE R16. 

HATCI specified making the dismissal 

procedure more complex than buckling 

the belt. NADA noted that dismissal or 

suppression would help address 

consumer acceptance concerns with the 

indefinite warning. Auto Innovators also 

suggested allowing deactivation of the 

audible rear seat warning. Auto 

Innovators believes that this approach 

would minimize potential consumer 

acceptance issue in circumstances 

where there may be a frequent change 

in the status of rear row occupancy and 

movement of occupants between seating 

positions such as ridesharing. Rivian 

recommended that NHTSA permit a 

reset or discontinue feature for instances 

in which a system with occupant 

detection detects that a seat becomes or 

is unoccupied to clear the audio-visual 

warning for front and rear occupants 

who exit the vehicle. Consumer Reports 

commented that it would be reasonable 

to allow drivers to ‘‘acknowledge and 

dismiss’’ warnings on a trip-by-trip 

basis to address drop-off situations, seat 

position changes, and situations 

involving fastening the wrong buckle. 

Anonymous #24 and Anonymous #33 

commented that a potential issue with 

the rear seat belt warning systems is the 

frequency with which individuals use 

rear seat space for storage or 

transportation of items large enough to 

trigger a seat belt warning system. 

Accordingly, Anonymous #24 argued 

that there should be an option for the 

vehicle operator to dismiss the warning 

in situations in which the seat belt 

reminder system is triggered by items 

other than people in the rear seat. 

Regarding hardening features, Auto 

Innovators and HATCI did not support 

additional hardening features due to the 

added technical complexity and 

implementation cost that would be 

required to reduce the potential for 

intentional and inadvertent defeat and 

activation. 

On the other hand, Ms. Tombrello 

commented that it is important to 

address occupants who may 

intentionally try to circumvent seat belt 

reminder systems such as a scenario in 

which seat belts are buckled while 

passengers sit on top of the belt. 

GM commented that NHTSA should 

also consider allowing suppression or 

dismissal of the front seat reminder 

audible warning in specialty vehicles 

such as police cars to allow for cases 

where the officer needs to communicate, 

whether with other law enforcement, 

first responders, or on radio devices, 

without the interference of background 

chimes in the vehicle. 

Agency Response 

The final rule does not allow 

deactivation or acknowledgement and 

dismissal of the front or rear seat belt 

warnings. As 87.7 percent of front seat 

occupants already always use their seat 

belts, the large majority of the overall 

population will not encounter the 

indefinite warning and, therefore, are 

unlikely to find it annoying. 

Furthermore, based on the Kidd and 

Chu study, we have at the very most 

only 8.4 percent (5.4 percent (never 

users) + 3.0 percent (44 percent × 6.9 

percent of sometimes users)) of the total 

population that would not be accepting 

of this as a standard feature. Therefore, 

allowing deactivation or 

acknowledgement and dismissal, would 

reduce safety benefits of the final rule 

even though there is general acceptance 

of this feature. Even temporary 

dismissal can reduce effectiveness by 

increasing the time before a change-ofstatus situation is addressed. 

Additionally, warnings lose 

effectiveness if drivers regularly dismiss 

the warning. Instead of deactivation or 

dismissal, this final rule contains 

multiple provisions and changes from 

the NPRM designed to maximize 

consumer acceptance while retaining 

the effectiveness of the belt warnings. 

The alerts required are now either short 

duration (for which driver annoyance is 

low) or are active in situations where 


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197Highway Loss Data Inst., Ins. Inst. for Highway 

Safety, Unbelted: Adults Admit They Often Skip 

Belts in Rear Seat, 52 Status Rep. 1, 3 (Aug. 3, 

2017). 

belt use is critical. For instance, the 

start-of-trip audible warning system for 

the front seats and the change-of-status 

audible warning system for the rear 

seats now only have a 30 second 

minimum duration, which is short 

enough to have only a limited consumer 

annoyance impact. An indefinite 

duration audible warning is required 

only for front seats for speeds at or over 

10 km/h (6.2 mph), at which point 

allowing deactivation or dismissal not 

only reduces effectiveness but defeats 

the purpose of an indefinite alert. There 

is also a variety of research, cited 

throughout this document and in the 

NPRM, regarding the high level of 

consumer acceptance for seat belt 

warning systems. 

Additionally, a few commenters such 

as Consumer Reports brought up 

scenarios that may generate false 

warnings, such as passenger pick-up 

and drop-off, or rear seat occupants 

switching seats during a trip, for which 

they argued that driver deactivation (or 

dismissal) is the appropriate response. 

This comment does not convince the 

agency that deactivation or dismissal is 

needed because in this final rule we 

have addressed many of these scenarios 

through other means. Regarding 

passenger pick-up and drop-off, this 

final rule allows systems to treat a door 

opening as the start of a new trip, 

resetting the change-of-status warning 

for the rear seats. For the front seats, the 

finalized requirements require only a 

visual change-of-status warning 

(assuming that, because the vehicle is 

stopped in a pick-up and drop-off 

scenario, the second phase warning 

would not activate), but the door reset 

provision would still apply to that 

visual change-of-status warning. For 

seat-switching in the rear, this final rule 

now contains a provision allowing a 

system to deactivate the warning if the 

system has determined that rear 

occupants have switched seats. 

We also received comments regarding 

items placed on the rear seat, which is 

addressed elsewhere in this final rule. 

We note here that this rule does not 

preclude designs that do not activate a 

passenger seat belt warning if the seat 

belt is fastened and no one is in the seat. 

Thus, nuisance warnings due to cargo 

could be prevented by buckling the seat 

belt or placing the cargo somewhere 

else. NHTSA understands that these 

provisions may not account for all 

scenarios and warnings may still cause 

some unneeded annoyance. However, 

we believe that this rule properly 

balances effectiveness with consumer 

acceptance. Therefore, NHTSA is not 

going to allow deactivation or dismissal 

in this final rule. 

We also note two items in response to 

some commenters’ requests to 

harmonize with ECE R16 to allow 

deactivation and dismissal of front 

warnings. First, regarding the visual 

alert, this final rule is harmonized with 

ECE R16 in that it does not allow 

dismissal. This is in part because visual 

warnings cause little annoyance to the 

driver and have a low impact on 

consumer acceptance. Second, 

commenters such as NADA stated that 

their reasons for seeking harmonization 

on deactivation or dismissal centered on 

consumer acceptance grounds. As 

noted, these concerns have largely been 

addressed through other means. 

Additional harmonization may reduce 

this rule’s effectiveness even if, as some 

commenters suggested and ECE R16 

requires, the rule were to require a 

short-term deactivation to be more 

difficult than buckling the belt. 

Therefore, we have determined not to 

harmonize on deactivation or dismissal 

of the audible warnings. 

We have also decided not to 

incorporate required hardening features 

or features to prevent circumvention of 

the system because, as some 

commenters pointed out, they increase 

the cost and complexity of warning 

systems without providing 

corresponding benefits. Although these 

requirements could increase benefits for 

the hardcore belt non-users, these 

benefits are unclear because most rear 

seat belt non-users are not hardcore and 

are less likely to intentionally 

circumvent the warning system.197 We 

note that manufacturers do have the 

discretion to incorporate such features if 

they choose to. This decision 

harmonizes with ECE R16 and Euro 

NCAP, which do not require such 

features. 

Finally, we are not including a 

deactivation provision for the front seat 

belt warning specific to law 

enforcement vehicles. FMVSS No. 208 

has required a warning system for the 

driver’s seat in law enforcement 

vehicles for many years without issue. 

Commenters did not suggest that 

extending the requirement to the front 

outboard passenger seat would create a 

concern. NHTSA understands that there 

may be additional considerations for 

law enforcement vehicles given some of 

the changes to the audible alert itself in 

this rule. However, currently NHTSA 

does not believe these considerations 

are sufficient to change the 

requirements specific to such vehicles. 

Like emergency vehicles, these vehicles 

are often modified by the purchaser to 

accommodate specific concerns, and the 

FMVSS do not prohibit such purchaser 

modifications. As with emergency 

vehicles, NHTSA will also monitor the 

situation and can modify this approach 

in future rulemaking actions, if 

necessary. 

7. Vehicles With Automated Driving 

Systems 

In the NPRM, NHTSA proposed 

incorporating certain language to tailor 

aspects of this rule to vehicles with 

ADS, which may be designed 

differently, to maintain the same level of 

occupant protection in vehicles 

equipped with ADS as in conventional 

vehicles. For example, such vehicles 

may not have a driver’s designated 

seating position or may have multiple 

front outboard passenger seating 

positions. Therefore, we proposed that 

the front passenger warning apply to 

‘‘any’’ front outboard passenger. The 

addition of the term ‘‘any’’ makes it 

clear that, in some vehicles, there may 

be more than one front outboard 

passenger seating position. We also 

noted that in a dual-mode vehicle, the 

left front seat is still by definition a 

driver’s seat, regardless of the 

operational status of the vehicle, so a 

provision to just have a warning for the 

driver and right outboard passenger 

would be sufficient to assure that all 

front seat outboard occupants receive a 

warning. Additionally, because some 

ADS-equipped vehicles have one or no 

front outboard passenger seats, we also 

proposed to align this final rule with the 

2022 final rule updating occupant 

protection standards to incorporate 

considerations for vehicles with ADS 

and apply the same seat belt warnings 

for front inboard passenger seats as front 

outboard seats. Finally, we noted that 

NHTSA was not prepared to propose a 

solution for the visibility of rear seat 

belt warnings for ADS-equipped 

vehicles and that it was beyond the 

scope of the proposed rule. 

Comments 

AVIA commented that as NHTSA 

continues to promulgate safety 

standards to integrate emerging 

technologies into motor vehicles, AVIA 

encourages the agency to ensure that 

any new regulatory requirements 

include considerations for how 

autonomous vehicles can meet those 

standards. 

Tesla supported the proposed 

warning on vehicle start up for front 

outboard passenger seats because it 

aligns with manually driven vehicles as 

well as partial and full automation, but 


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198As discussed in Section VI.B.4, many 

commenters expressed concerns with redesign costs 

associated with a requirement that the telltale be 

visible to the passenger. Although NHTSA sought 

comment on aspects of the NPRM regarding 

vehicles with ADS, commenters focused their 

concerns on conventional vehicles. Therefore, 

NHTSA does not believe that such concerns are 

present to the same degree with vehicles without 

a driver’s designated seating position. 

199 87 FR 18560. 

asked how the change-of-status warning 

for front seats requirement will be 

applied to autonomous vehicles. 

Agency Response 

We have added language to tailor 

aspects of the rule for vehicles with 

automated driving systems in order to 

maintain the same level of occupant 

protection as this final rule requires for 

conventional vehicles. Some of these 

elements are discussed in other sections 

of this document specific to aspects of 

the rule. For example, in Section VI.B.4 

we discuss an exception to the front seat 

visual warning visibility requirement 

that is necessary for dual-mode ADS 

and in Section VI.B.5 we address 

occupant detection as it relates to dualmode ADS. Here, we note a few 

additional items. 

First, we are finalizing without 

change two items from the NPRM: one, 

to apply the front seat belt warning 

requirements to ‘‘any’’ front outboard 

designated seating position and two, to 

apply the same seat belt warnings for 

certain front inboard passenger seats as 

front outboard seat. We did not receive 

comment specific to these items 

intended to accommodate vehicles with 

ADS that may not have conventional 

seating configurations. 

Second, to accommodate other 

changes in the final rule, we have 

included language regarding telltale 

visibility as applied to certain vehicles 

with ADS to maintain the same level of 

occupant protection as this rule requires 

for conventional vehicles. As noted in 

Section VI.B.4, this rule requires the 

front outboard passenger seat belt visual 

warning to be visible only to the driver. 

Additionally, this final rule requires 

that for telltales associated with 

multiple front outboard seats, the seat 

with which each telltale is associated 

must clearly identify the seating 

positions for which the warnings are 

intended. This requirement is discussed 

further in Section VI.C.3. As many 

commenters pointed out and we 

explained, in vehicles with a driver, the 

front outboard passenger can receive the 

audible signal and the driver can 

communicate the additional information 

provided by a visual signal to the front 

outboard passenger. However, in 

vehicles with ADS, there may not be a 

driver’s designated seating position with 

a human driver who can receive and 

communicate this information. Instead, 

as we noted in the NPRM, in a vehicle 

without manually operated driving 

controls, one of the front passengers 

may be performing the management role 

for the duration of a trip, such as in the 

case of a parent and children. In this 

circumstance, the most appropriate 

recipient of the visual warning is likely 

to be a front passenger. 

For these reasons, we are finalizing 

two provisions. First, we are finalizing 

as proposed that for vehicles that do not 

have a driver’s designated seating 

position, the visual warning for each 

front outboard passenger designated 

seating position must be visible from 

each front outboard passenger 

designated seating position. Second, we 

are now requiring that for vehicles 

without a driver’s designated seating 

position, for telltales associated with 

multiple front outboard seats, the seats 

with which each telltale is associated 

must clearly identify the seating 

positions for which the warnings are 

intended. These requirements maintain 

the same level of occupant protection as 

is required for conventional vehicles 

and is also consistent with the logic of 

the NPRM.198

As we stated in the 2022 final rule on 

occupant protection for vehicles with 

ADS, these requirements are intended to 

apply only to ADS-equipped vehicles 

that have seating configurations similar 

to non-ADS vehicles, i.e., forward-facing 

front seating positions (conventional 

seating). As we stated in the 2022 final 

rule, additional research is necessary 

(some of which is currently underway) 

to understand and address different 

safety risks posed by vehicles with 

unconventional seating arrangements 

(e.g., rear-facing seats or campfire 

seating), including with regards to seat 

belt reminder systems.199 Therefore, as 

we stated in Section VI.B.3 of this 

document in response to AVIA’s 

comment about front seat occupants 

exiting through a door not adjacent to 

their seat, considerations for vehicles 

with unconventional seating (and other 

related considerations, such as bidirectional vehicles) are out of scope of 

this final rule. Additionally, as noted in 

the NPRM, the visibility of rear seat belt 

warnings for ADS-equipped vehicles is 

also out of scope of this final rule 

because further research is needed 

before the agency proposes a solution. 

Research on this topic is underway. 

Finally, we believe the final rule has 

addressed in prior sections Tesla’s 

concern about change-of-status 

warnings for front seats in vehicles 

operating in an automated state. 

8. Test Procedures 

In the NPRM, NHTSA proposed that 

NHTSA could test any system under 

any combination of seat occupancy or 

seat belt use status. The proposed test 

procedures also specified how the 

agency would test a seat belt warning 

system with a designated seating 

position that is occupied. The finalized 

occupancy criteria (the test dummies 

and the height and weight criteria for 

human beings, to be used instead of test 

dummies at the manufacturer’s option, 

that will be used to determine 

occupancy) are discussed in Sections 

VI.A.2.a.iv (rear) and VI.B.5 (front 

passenger). The NPRM also proposed 

that to pass the test, the human beings 

or test dummies used would be seated, 

the seat belt use and ignition conditions 

would be applied, and the required 

signals must operate (that is, either 

activate or not activate) accordingly. 

The test could be conducted with the 

seat and adjustable belt anchorages in 

any position. The NPRM also noted that 

for rear designated seating positions 

with occupant detection, the agency 

would perform the test with the seat in 

any position, the seat back in the 

manufacturer’s nominal design riding 

position, and any adjustable anchorages 

in any position. 

Comments 

Auto Innovators requested that 

NHTSA publish the proposed test 

procedures used to evaluate vehicle 

compliance before issuance of the final 

rule. Auto Innovators stated that this 

request is particularly relevant given the 

differences in the requirements in the 

NPRM when compared to the current 

requirements of ECE R16, and 

stakeholders’ desire for the opportunity 

to address any technical concerns before 

the rule or test procedure is finalized. In 

particular, Auto Innovators sought 

additional information regarding how 

NHTSA will evaluate the performance 

of an indefinite alert. 

Auto Innovators also commented that 

the agency should more closely align its 

requirements with ECE R16 and Annex 

18 to reduce test burden costs, in 

particular regarding the process for 

evaluating the conditions for warning 

activation. Auto Innovators also 

commented that the proposal increases 

the complexity of evaluating vehicle 

compliance and may require specialized 

equipment or similar measurement 

devices to verify the characteristics of 

the proposed audible warning. 

Finally, Auto Innovators 

recommended that NHTSA ensure a 

technology neutral approach, both for 

performance requirements and test 


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Federal Register / Vol. 90, No. 2 / Friday, January 3, 2025 / Rules and Regulations 441 

200The Safety Act establishes a self-certification 

process in which vehicle and equipment 

manufacturers certify that their products comply 

with all applicable FMVSS, which establish 

minimum performance standards that the product 

must meet. It is up to manufacturers to determine 

what steps are necessary to ensure that every 

product manufactured meets or exceeds the 

applicable requirements before the products are 

imported, sold, offered for sale, or introduced into 

interstate commerce in the United States. 

procedures, towards the means used to 

determine occupant detection. 

Agency Response 

The final rule incorporates several 

changes to the proposed regulatory text 

for the test procedures: 

• Definition of ‘‘seat centerline’’— 

Both the proposed and finalized test 

procedures specify the seating of the test 

dummy by reference to the ‘‘seat 

centerline.’’ The final regulatory text 

includes a definition of this term. 

• Occupancy criteria—The proposed 

regulatory text specified these in the 

definitions section. In the final rule 

these have been moved to the test 

procedures section and edited for 

clarity. 

• Test procedures—The final rule 

clarifies several aspects of how the test 

may be carried out. The final rule does 

not include the proposed specification 

that if a human occupant is used for 

testing, that they be dressed in a cotton 

T-shirt, full length cotton trousers, and 

sneakers, instead we are specifying that 

the dummy or human occupant may be 

clothed in any manner because clothing 

should not change the performance of 

the system. With respect to carrying out 

testing, the proposed regulatory text 

simply stated, ‘‘Place the ignition switch 

in the ‘‘on’’ or ‘‘start’’ position and 

verify that the seat belt warnings 

function as specified in S7.5(b) and 

S7.5(c), for any combination of seat belt 

use or seat occupancy at any designated 

seating position(s).’’ The final rule 

clarifies that NHTSA could test any of 

a number of test parameters: ‘‘Verify 

that the seat belt warnings function as 

specified in S7.5(b) and S7.5(c), for any 

combination of seat belt use (at any 

seating position), seat occupancy (at any 

seating position), removable seat 

electrical connection status (connected 

or not connected, for any removable 

seat), vehicle speed, and door status 

(open or closed, for any door), except 

that the door shall not be opened when 

the vehicle is in motion.’’ 

NHTSA is not publishing the 

compliance laboratory test procedures 

before publishing this final rule as 

requested by Auto Innovators. To 

investigate whether specific vehicles or 

products comply with the FMVSS, 

NHTSA’s Office of Vehicle Safety 

Compliance (OVSC) contracts with labs 

to conduct compliance testing. OVSC 

laboratory test procedures are prepared 

for the limited purpose of use by 

contracted independent laboratories 

conducting compliance tests for the 

OVSC. OVSC laboratory test procedures 

are distinct from regulatory test 

procedures that are included as part of 

most FMVSS. OVSC laboratory test 

procedures are generally based off of the 

regulatory test procedures in specific 

FMVSS but are prepared by the agency 

to give contracted labs specific 

instructions on how to conduct a 

specific test. The OVSC laboratory test 

procedures are simply agency guidance 

for contracted labs and do not constitute 

official agency action (e.g., a rule). In 

some cases, the OVSC laboratory test 

procedure, or the report produced as a 

result of the work performed by the 

contracted laboratory, does not include 

all of the various FMVSS minimum 

performance requirements. Because the 

OVSC laboratory test procedures are not 

part of the regulation, NHTSA is not 

required to publish them prior to or 

with this final rule. Typically, NHTSA 

will publish the OVSC laboratory test 

procedures on its website for 

transparency. NHTSA plans to publish 

the OVSC test procedures for this rule 

in the future. 

NHTSA also declines to specify in the 

FMVSS the exact amount of time that it 

will test the indefinite front outboard 

seat belt warnings. NHTSA believes that 

specifying a finite testing duration 

would weaken the rule by enabling 

systems that are not indefinite to meet 

the test. Manufacturers must certify that 

their products comply with all 

applicable FMVSS, and they determine 

what steps are necessary to ensure that 

every product manufactured meets the 

applicable requirements. The 

procedures in this rule are sufficiently 

detailed and objective for manufacturers 

to self-certify that their systems meet the 

indefinite warning requirement. 

NHTSA agrees with Auto Innovators 

that this final rule should be technology 

neutral toward occupant detection, and 

this rule is technology neutral. As 

discussed in Section VI.B.5, this final 

rule does not require occupant detection 

capability for the driver’s designated 

seating position. It provides 

manufacturers the flexibility to 

optionally choose to certify compliance 

to the same occupant detection criteria 

applied to the outboard passenger seats. 

Additionally, while the final rule 

requires occupant detection capability 

for the front outboard passenger 

designated seating position and 

specifies seat occupant criteria for 

testing front outboard passenger 

designated seating positions and rear 

designated seating positions, it does not 

specify the methods that must be used 

to detect occupancy. Manufacturers may 

choose occupant detection technologies 

at their discretion, so long as they can 

certify that the vehicle meets the 

requirements of this final rule and the 

test procedure it specifies. The same is 

true for the technology that OEMs may 

use to detect whether the seat belt is in 

use. 

Throughout this final rule NHTSA has 

considered harmonization and has taken 

care, where possible, to incorporate 

performance requirements and test 

procedures that can enable systems to 

also meet ECE R16 requirements to 

minimize testing and compliance costs 

for manufacturers. Therefore, while this 

final rule does not fully align with the 

test procedures in ECE R16 Annex 18, 

they are largely compatible. As noted in 

the NPRM, ECE R16 operates in a type 

approval regime, while the FMVSS use 

self-certification and must be objective. 

For this reason, the final rule departs 

from Annex 18 when necessary to 

ensure that it is objective. Because of 

these necessary differences to meet 

statutory obligations, full alignment of 

the test procedures is not achievable.200

Finally, with respect to Auto 

Innovators’ concern about specialized 

test equipment needed to verify 

compliance with the required audible 

warning characteristics, this final rule 

does not establish test procedures that 

necessitate specialty equipment that 

laboratory test facilities would not 

already have readily available (e.g., a 

stopwatch) to verify compliance of the 

audible warnings. 

VII. Regulatory Alternatives 

In the proposal, NHTSA considered 

several major alternatives: harmonizing 

with the standards set in ECE R16 and 

Euro NCAP; requiring occupant 

detection and enhanced warning signals 

for the rear seat belt warning; requiring 

a warning for the front center seat; 

requiring an audio-visual seat belt 

warning for the front outboard seating 

positions with a duration not less than 

90 seconds; and a few non-regulatory 

alternatives. For three of these 

alternatives (rear-seat occupant 

detection, front center seat warning, and 

90-second front warning), NHTSA 

quantified the costs and benefits (see 

Section VIII.B). Although the proposal 

followed ECE R16 and Euro NCAP in a 

variety of ways, it also deviated from 

them in some important respects. The 

NPRM explained this deviation in 

detail. The NPRM also explained 

NHTSA’s tentative reasoning for not 


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442 Federal Register / Vol. 90, No. 2 / Friday, January 3, 2025 / Rules and Regulations 

201H.R. 3684 (117th Congress) (2021) section 

24211. 

selecting the other regulatory 

alternatives. 

Comments 

NHTSA received many comments 

concerning the regulatory alternatives. 

Comments regarding alternatives for 

specific aspects of the proposal are 

discussed throughout the preceding 

sections of the preamble. Many of these 

comments concerned harmonization 

with the relevant provisions in ECE R16, 

Euro NCAP, and the IIHS protocol. 

Safety advocates in several instances 

favored final requirements that would 

be more stringent or demanding than 

those requirements or protocols. On the 

other hand, industry commenters 

generally—although not always— 

commented in support of greater 

alignment with them. In this section, 

NHTSA summarizes and addresses 

comments that concerned 

harmonization generally, as well as 

comments concerning non-regulatory 

alternatives. 

In addition to the more specific 

comments already addressed in this 

document, several industry commenters 

commented more generally in favor of 

harmonization with ECE R16 and Euro 

NCAP. Auto Innovators, Hyundai, 

HATCI, IEE, NAMIC, and Nissan 

commented in support of harmonizing 

the requirements with ECE R16 and 

Euro NCAP. Auto Innovators 

commented that harmonization with 

ECE R16 provides the agency with the 

greatest opportunity to ensure an 

objective and practical approach that 

meets the need for safety, while also 

minimizing regulatory burden and 

corresponding delays associated with 

developing region-specific features for 

the U.S. market. Auto Innovators 

expressed concerns with several areas 

where the agency has proposed 

alternatives to the requirements of ECE 

R16, which have already been widely 

adopted and implemented in other 

global markets. Auto Innovators argued 

that several fundamental aspects of the 

proposal (such as the triggering 

conditions) differ from the systems that 

consumers may have experienced in 

both previous and current model year 

vehicles and would result in significant 

negative pushback from the public if the 

final rule is adopted without change. 

Hyundai similarly commented that 

although it supported the proposal, its 

largest caveat to full support was the 

proposal’s departure from ECE R16’s 

requirements. Hyundai characterized 

these differences as minor in the sense 

that they do not represent any 

fundamental change to the core 

elements or safety benefits of NHTSA’s 

proposal but stated that these ‘‘minor’’ 

differences could have significant 

adverse implications with respect to 

safety benefits, customer acceptance, 

unnecessary country-specific designs, 

costs, and required lead times. Hyundai 

commented that the benefits of 

international regulatory harmonization 

have been recognized and espoused by 

government and industry organizations, 

including NHTSA, for many years. 

Hyundai argued that these benefits 

include improved regulatory and NCAP 

provisions that reflect the international 

consensus of leading government and 

industry experts, more efficient 

development and timely enactment of 

state-of-the-art vehicle safety provisions, 

enabling international trade and 

cooperation by reducing nontariff 

barriers, more effective use of finite 

government and industry resources, 

avoidance of country-specific 

requirements, and significantly reduced 

consumer costs. 

HATCI also noted that the 

requirements that the agency has 

proposed would require significant 

interior redesign which would require 

longer design lead time. HATCI 

encouraged the agency to further 

harmonize with established 

international regulations and rating 

programs, allow for more flexible 

telltale design, and extend the effective 

dates. 

GM, NSC, SRN, Hyundai, HATCI, and 

an individual commenter also 

supported the inclusion of seat belt 

reminder ratings in NCAP. Hyundai 

recommended that NHTSA coordinate 

its FMVSS and NCAP initiatives to 

pursue maximum safety benefits in the 

shortest feasible timeframes; by virtue of 

being voluntary, NCAP enables vehicle 

safety technology to be socialized in a 

non-compulsory way to enhance 

consumer acceptance. Hyundai 

suggested that a follow-on NCAP action 

might incentivize some form of a socalled ‘‘Seat Belt Assurance System’’ 

(e.g., limiting infotainment functionality 

or constraining vehicle speed when an 

occupant is unbuckled) to further 

motivate buckling up. Hyundai stated 

that this suggested NCAP update could 

also specify requirements regarding 

bypassing/disablement to obtain credit 

for the specified Seat Belt Assurance 

System. Hyundai argued that a timely 

progression of FMVSS and NCAP 

actions by NHTSA could appreciably 

improve seat belt use rates and 

consumer acceptance of these vehicle 

interventions. SRN commented that if 

NHTSA did not require the full-status 

rear seat warning system, it could 

reward vehicles with these more 

effective systems with NCAP points. 

Consumer Reports agreed with 

NHTSA’s decision not to pursue either 

of the non-regulatory alternatives 

presented in the ANPRM. 

Agency Response 

Because NHTSA is amending FMVSS 

No. 208 to include these new 

requirements, it is not necessary to 

incorporate these requirements into 

NCAP. To help consumers make 

purchasing decisions, NHTSA currently 

indicates on a vehicle’s NCAP safety 

rating web page if the vehicle has a seat 

belt reminder system for the front and/ 

or rear passengers. NHTSA may at a 

later date, as suggested by some 

commenters, consider using NCAP to 

incentivize enhanced rear seat belt 

reminder systems. NHTSA also concurs 

with Consumer Reports not to pursue 

either of the non-regulatory alternatives 

presented in the ANPRM. 

In developing the requirements in this 

final rule, NHTSA considered the 

requirements in ECE R16, as well as 

materials published by Euro NCAP and 

IIHS. NHTSA agrees with the 

commenters that harmonization is an 

important goal and agrees that in some 

specific instances that the proposal 

should be modified to align more 

closely with ECE R16, Euro NCAP, and 

IIHS. 

Executive Order 13609 provides that 

international regulatory cooperation can 

reduce, eliminate, or prevent 

unnecessary differences in regulatory 

requirements. Similarly, the 

Infrastructure, Investment, and Jobs Act 

directs that ‘‘[t]he Secretary [of 

Transportation] shall cooperate, to the 

maximum extent practicable, with 

foreign governments, nongovernmental 

stakeholder groups, the motor vehicle 

industry, and consumer groups with 

respect to global harmonization of 

vehicle regulations as a means for 

improving motor vehicle safety.’’ 201

(These directives are also discussed in 

the Regulatory Analyses section.) At the 

same time, the Safety Act authorizes 

NHTSA to establish motor vehicle safety 

standards that, among other things, meet 

the need for safety and are practicable. 

Consistent with these directives, and 

after NHTSA has carefully considered 

the comments, the final rule more 

closely aligns with those regulatory 

alternatives where warranted but 

continues to deviate from them where 

necessary. The preceding sections of 

this document discuss in detail the 

ways in which the final rule follows and 

differs from these regulatory alternatives 

and explains why we believe the 


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202The final rule makes no distinction between 

start-of-trip and change-of-status visual warnings. It 

has been combined into one single visual warning 

requirement, so the triggering and duration 

characteristics summarized here are for the single 

visual warning requirement. 

departures are justified. The major 

provisions in the final rule and the 

regulatory alternatives, including the 

differences between them, are 

summarized in table 10. 

TABLE 10—COMPARISON OF FINAL RULE WITH REGULATORY ALTERNATIVES

Topic Final rule UN ECE R16 Euro NCAP IIHS 

Rear Seat Belt Warning Requirements 

Applicability ............................... Excludes small school buses, 

law enforcement vehicles, 

and ambulances.

Excludes all small buses and 

more categories of specialpurpose vehicles.

Excludes commercial vehicles 

and most vehicles over 

3,500 kg.

N/A. 

Occupant detection ................... Not required ............................. Not required ............................. Awards points only for systems 

with occupant detection.

Not required. 

Visual Warning on vehicle startup: 

Type of information conveyed by visual signal.How many or which seat belts 

are in use and/or not in use.

Indicates at least all rear seats 

to allow the driver to identify 

any seat where the belt is 

not in use.

Indicates the rear seat belts in 

use and not in use.

Whether the seat belt at each 

rear seating position is in 

use or not in use. 

Triggering Conditions ........ Ignition switch on/start or (for 

EVs) propulsion activation.

Master control switch activated Ignition switch is engaged (engine running or not).Engine/motor on; allows 10- 

second delay. 

Seat Occupancy Criteria ... 6-year-old ................................ 5th percentile female ............... 5th percentile female ............... Seated human or dummy in 

front passenger seat and 

human in rear seat (unspecified size). 

Duration ............................. 60 seconds .............................. 60 seconds .............................. 60 seconds .............................. 60 seconds. 

Audio-Visual Change-of-status 

warning: 

Duration ............................. 30 seconds .............................. 30 seconds .............................. 60 second visual warning; 30 

second audible warning.

30 seconds. 

Triggering Conditions ........ Fastened belt becomes unfastened, the vehicle is in forward or reverse, and all rear 

doors remain closed.

Fastened belt becomes unfastened and certain distance, 

time and/or speed threshold(s) are exceeded.

Fastened belt becomes unfastened, certain distance, time 

and/or speed threshold(s) 

are exceeded, and all rear 

doors remain closed.

Fastened belt becomes unfastened, certain distance, time 

and speed threshold(s) are 

exceeded, and all rear doors 

remain closed. 

Front Seat Belt Warning Requirements 

Applicability ............................... Excludes all heavy vehicles .... Does not exclude heavy vehicles used for carrying goods.N/A ........................................... N/A. 

Front Seating Positions ............ Front outboard passenger and 

driver (not center seat).

All positions in the same row 

as the driver.

All front row positions .............. Front outboard. 

Visual Warning—start-of-trip: 202

Triggering Conditions ........ Seat occupied, belt unfastened, ignition on/start or (for 

EVs) propulsion activation.

Belt unfastened, ignition or 

master control switch engaged.

Belt unfastened, ignition switch 

engaged.

Concurrent with audible. 

Duration ............................. Until belt is fastened ................ 30 seconds .............................. Until belt is fastened ................ Concurrent with audible. 

Visual Warning—Change-ofStatus: 

Triggering Conditions ........ Seat occupied, belt unfastened, ignition on/start or (for 

EVs) propulsion activation.

If belt remains unfastened and 

certain distance, time, and/or 

speed threshold (25 km/h 

(15.5 mph)) are exceeded.

Belt unfastened, speed over 

25 km/h (15.5 mph).

Concurrent with audible. 

Duration ............................. Until belt is Fastened .............. At least 30 seconds not counting gaps over 3 seconds.Until belt is fastened ................ Concurrent with audible. 

Audible Warning—First Phase: 

Triggering Conditions ........ Seat occupied, belt unfastened, ignition on/start or (for 

EVs) propulsion activation.

If belt remains unfastened and 

certain distance, time, and/or 

speed threshold (25 km/h 

(15.5 mph)) are exceeded.

Must be deployed before and 

certain distance, time, and/or 

speed threshold (25 km/h 

(15.5 mph)) are exceeded 

(‘‘final’’ signal if other, higher 

thresholds are met).

Seat occupied, belt unfastened 

at ignition, continuous forward motion of at least 10 

km/h (6.2 mph). 

Duration ............................. 30 seconds .............................. At least 30 seconds ................. May not exceed 30 seconds 

(‘‘final’’ signal at least 90 

seconds).

90 seconds. 

Audible Warning—Second 

Phase: 

Triggering Conditions ........ Seat occupied, belt unfastened, and a speed ≥10 km/ 

h (6.2 mph).

Fastened belt becomes unfastened and certain distance, 

time and/or speed threshold(s) (25 km/h (15.5 mph)) 

are exceeded.

Fastened belt becomes unfastened, vehicle speed over 25 

km/h (15.5 mph) (‘‘final audible signal’’ if over 40 km/h 

(24.9 mph)).

Occupied seat, belt unfastened, continuous forward 

motion of at least 10 km/h 

(6.2 mph). 

Duration ............................. Until belt is fastened or speed 

<10 km/h.

At least 30 seconds ................. At least 90 seconds ................. 90 seconds. 


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444 Federal Register / Vol. 90, No. 2 / Friday, January 3, 2025 / Rules and Regulations 

203The FRIA is available in the docket for this 

final rule and may be obtained by downloading it 

or by contacting Docket Management at the address 

or telephone number provided in the ADDRESSES

section of this document. 

204 Kidd and O’Malley titled ‘‘Increasing seat belt 

use in the United States by promoting and requiring 

more effective seat belt reminder systems.’’ https:// 

pubmed.ncbi.nlm.nih.gov/37267012/#:∼:text=

If%20every%20vehicle%20in%20the,85.9%

25%20in%20the%20rear%20row. 

TABLE 10—COMPARISON OF FINAL RULE WITH REGULATORY ALTERNATIVES—Continued 

Topic Final rule UN ECE R16 Euro NCAP IIHS 

Visual Warning Characteristics Must provide telltale specified 

in FMVSS No. 101, Table 2, 

the seat to which the telltale 

is associated must be clearly 

identified.

Specifies image identical to 

FMVSS No. 101, Table 2.

N/A ........................................... Indicate an outboard front-row 

seating position with an unfastened belt. 

Other Requirements 

Audible Warning Characteristics: 

Cycle, Chime Frequency, 

Signal Gaps.

Front First Phase and Rear: 

Gap limitations.

Front Second Phase: Specifies 

duty cycle, warning cycle, 

and chime frequency. No 

gap limitations.

Gap limitations ......................... Gap limitations ......................... Gap limitations. 

Volume ............................... No volume requirement ........... ‘‘easily recognizable by the 

driver’’.

Final audible warning must be 

‘‘loud and clear’’.

Must be between 20 and 

20,000 Hz and must include 

at least one dominant frequency between 500 and 

2,250 Hz. 

Warning Deactivation, Acknowledgement, and Dismissal.Not permitted ........................... Short and long-term deactivation of the audible warning 

with limitations, including 

that it must be more difficult 

to effectuate a short-term 

deactivation than to buckle 

the belt.

Acknowledgement allowed for 

rear seats but not for the 

change-of-status warning.

Rear visual signal may be cancelled by the driver. 

VIII. Overview of Benefits and Costs 

NHTSA has prepared a Final 

Regulatory Impact Analysis (FRIA) that 

assesses the benefits, costs, and other 

impacts of this final rule.203 For a more 

detailed discussion, please refer to the 

FRIA. The following sections present 

the benefits and costs of the final rule 

requirements for the rear and front 

SBWSs and the three major regulatory 

alternatives considered. It is important 

to note that the incremental benefits 

presented in the section stem not from 

the SBWS’s function itself, but instead 

result from the increase in seat belt use 

brought about by the SBWS. Therefore, 

the incremental benefits associated with 

the final rule are comprised of the 

fatalities and non-fatal injuries 

prevented as a result of the increase in 

seat belt use from the SBWS. 

A. Final Rule Requirements 

NHTSA quantified the benefits and 

costs of the final rule requirements. This 

section presents a summary of the 

benefits and costs for the requirements 

on rear seat belt warning systems, front 

outboard seat belt warning systems, and 

the combined costs and benefits for both 

warning systems. 

1. Rear Seat Belt Warning System 

The September 2023 NPRM sought 

comment on the potential effectiveness, 

benefits, and costs of a rear seat belt 

warning. 

Comments 

1. Safety benefits for rear SBWS are 

underestimated: Consumer Reports 

commented in support of the proposed 

rule stating that the preliminary 

regulatory impact analysis (PRIA) likely 

underestimates the safety benefits 

associated with the requirements for the 

rear seats. Consumer Reports 

commented that the analysis did not 

factor in the technological 

advancements of current vehicle fleets 

which will likely increase the rate of 

injury for unrestrained rear seat 

passengers. More specifically, Consumer 

Reports noted that crash avoidance 

systems that are associated with hard 

braking and pre-crash maneuvers may 

result in an increased rate of injury to 

unrestrained rear seat passengers. 

Agency Response 

Regarding Consumer Reports’ 

comment on underestimating the 

benefits associated with rear SBWS, 

NHTSA has updated the target 

population in the final rule using the 

most recently available data along with 

adjustments to account for safety 

impacts of new required safety 

technologies that have yet to be applied 

to the fleet. These updates in the final 

rule correctly reflect the benefits for rear 

SBWS. This analysis does not project 

changes in ridership between front and 

rear seat occupants as such projections 

would introduce uncertainty into the 

analysis. However, if ride sharing 

services increase rear seat occupancy, it 

is possible that benefits for rear seat 

occupants could be greater than those 

estimated in this FRIA. 

2. Require occupant detection for rear 

seats: Commentors including Consumer 

Reports and NSC urged NHTSA to 

require SBWS with occupant detection 

for rear seats. These commenters also 

requested that the agency estimate 

benefits of the case that manufacturers 

would choose to implement negativeonly or full-status warning system 

stating that the projected increases in 

seat belt use from the rule would likely 

be greater if NHTSA required the fullstatus compliance option for all 

applicable vehicles. Consumer Reports, 

citing findings of an IIHS study,204

noted that benefits for rear seat 

occupants may be underestimated as 

NHTSA did not account for increases in 

rear seat passengers resulting from 

consumers increasingly using ride 

sharing services in recent years. 

Agency Response 

The final rule does not require 

occupant detection for the rear SBWS 

but permits it. Based on comments 

received, the final rule differs from the 

proposed rear SBWS requirements by 

permitting positive-only, negative-only, 


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Federal Register / Vol. 90, No. 2 / Friday, January 3, 2025 / Rules and Regulations 445 

205The target population in the PRIA reflected the 

2011–2015 FARS and 2011–2015 NASS/CDS data. 

The FRIA updated the target population to reflect 

more recent data. The NASS/CDS data previously 

used did not reflect injury data for vehicles older 

than ten years which may have underestimated 

injuries. 

206See FRIA, appendix A.7. 

207See FRIA, tables 25 and 26. 

and full-status SBWS without the use of 

occupant detection. We believe that 

while the full-status system (with 

occupant detection) does provide the 

driver with the most information, as we 

explained in the NPRM, we continue to 

believe that the other allowable types of 

systems without occupant detection 

would provide the driver with sufficient 

information to easily determine whether 

and where there are any unbuckled 

occupants and request that they fasten 

their seat belts. Although some vehicle 

manufacturers may implement warning 

systems with occupant detection, 

NHTSA estimated benefits based on 

vehicle manufacturers meeting the 

minimum requirements. Therefore, 

NHTSA estimated the incremental 

benefits and costs associated with the 

least costly compliance option, which is 

a rear SBWS without occupant 

detection. 

The study by Kidd and O’Malley, 

cited by Consumer Reports, compares 

the effectiveness of SBWS with different 

warning durations and system 

interlocks in increasing seat belt use. 

The study found that enhanced 

reminders, in particular more persistent 

reminders, are more effective in 

increasing seat belt use. Although 

system interlocks are effective in 

increasing seat belt use, they are found 

to be much less acceptable than audible 

reminders and more likely to be 

circumvented. The 2019 IIHS study by 

Kidd (used in the PRIA and in this final 

rule) found that moving from a 7-second 

warning to either a 90-second or 

indefinite duration warning increased 

seat belt use for part-time users by 30 

percent and 34 percent respectively. 

Overall, these studies provide evidence 

that the relative annoyance or duration 

of a warning increases the effectiveness 

of a SBWS. However, they do not 

provide any data that can be used to 

estimate the increase in seat belt use 

generated by adding occupant detection 

to the rear seat SBWS. 

Due to a lack of data, NHTSA is 

unable to estimate the increase in seat 

belt use for a SBWS with occupant 

detection compared with a SBWS 

without occupant detection. Therefore, 

the agency is unable to estimate 

incremental benefits for the regulatory 

alternative with occupant detection. 

Instead, NHTSA considered how much 

more effective a SBWS with occupant 

detection would need to be to generate 

the same net benefits as the final rule, 

which allows for a SBWS without 

occupant detection in the rear seat. 

Overall, a SBWS with occupant 

detection would need to increase seat 

belt use by approximately two to three 

times that of a SBWS without occupant 

detection to generate the same level of 

net benefits. As it is not likely that a 

SBWS would be two or three times as 

effective as one without occupant 

detection, this regulatory alternative 

was not selected. However, while 

occupant detection was not included as 

a requirement in the final rule, the 

finalized requirements do allow systems 

that have occupant detection. 

3. Cost burden for requiring SBWS on 

rear seats for high occupancy vehicles: 

Mercedes-Benz AG commented on the 

cost burden of implementing SBWS for 

rear seats in high occupancy vans. The 

commenter noted that for each 

removeable seat, an electronic control 

unit (ECU) would be required along 

with other hardware components and 

corresponding software. Additionally, 

one commenter indicated concern that 

the agency did not fully account for the 

potential burden on industry; in 

particular, in cases in which businesses 

will incur the cost of adding SBWS to 

vehicles with a large number of rear 

seats, such as vans and buses. 

Agency Response 

In estimating the costs associated with 

the final rule, the agency made use of 

end-user costs estimates from a 

teardown study. Those unit costs were 

then applied on a per-seat basis to the 

average number of seats per vehicle and 

average number of new light vehicles 

sold annually to estimate the total 

annual cost. NHTSA did not estimate 

costs on a per-manufacturer or perbusiness basis but instead provided the 

total annual cost to end users. This 

estimate reflects not only the cost of 

materials and labor incurred by 

manufacturers, but also non-production 

costs and profit reflected in the price 

passed down to consumers. 

Additionally, while the per-vehicle cost 

may vary based on the number of seats 

per vehicle, in vehicles with more rear 

seats, both costs and benefits will 

increase. While costs increase based on 

the number of seats in a vehicle, 

benefits increase not only based on both 

the number of restrained occupants that 

avoid injury due to their use of seat 

belts, but also due to the reduction in 

potential injuries from harmful 

interactions between unrestrained 

occupants. 

4. Lack of harmonization with existing 

standards increases cost: Commenters, 

including Auto Innovators and Tesla, 

encouraged harmonizing with other 

regulatory and safety ratings 

requirements. More specifically, Auto 

Innovators stated that the agency should 

consider potential costs associated with 

redesign due to misalignment with ECE 

R16. 

Agency Response: Throughout this 

final rule NHTSA has considered 

harmonization and has taken care to 

incorporate performance requirements 

and test procedures that can, in many 

cases, enable systems to also meet ECE 

R16 requirements to minimize testing 

and compliance costs for manufacturers. 

However, NHTSA declines to fully 

harmonize with the test procedures in 

ECE R16 Annex 18. Since NHTSA’s 

regulations follow a self-certification 

approach, it is important to include 

certain information in the FMVSS test 

procedures to ensure that they are 

objective and properly test for 

compliance with this final rule, which 

may not be necessary for ECE R16 

testing. 

In general, the rear seat belt warning 

system requirements in this final rule 

are consistent with those in ECE R16 

and Euro NCAP. One major difference is 

that ECE R16 evaluates occupant 

detection using the 5th percentile 

female dummy while the final rule 

specifies using a 50th percentile 6-yearold child or equivalent. For the reasons 

explained in a previous section, this 

final rule addresses a MAP–21 mandate 

and requires, if an occupant detection 

system is provided, that the system be 

able to detect children in the rear seats. 

The weight of a 5th percentile female 

dummy is greater than that of many 

children aged 6 to 16 years old and so 

it is not an appropriate surrogate for 

evaluating child occupancy. 

Summary of Analysis and Results 

Based on the Fatality Analysis 

Reporting System (FARS) and the Crash 

Investigation Sampling System (CISS) 

data from 2017 through 2021,205 on 

average 930 unrestrained rear seat 

occupants were killed in crashes and 

15,380 were injured annually.206 After 

adjusting these to account for future 

decreases in fatalities and injuries 

projected to occur in the absence of the 

finalized requirements due to the 

introduction of other mandatory safety 

technologies (e.g., electronic stability 

control), the analysis estimates a 

baseline of, on average, 822 fatalities 

and 11,409 injuries to unrestrained rear 

seat occupants each year.207 This is the 

overall target population for rear seat 

occupants—the annual deaths and 


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208See FRIA, table 33. 209Motoyuki Akamatsu et al., Assessment 

Method of Effectiveness of Passenger Seat Belt 

Reminder. 2012–01–0050, SAE International (2012). 210Survey of Principal Drivers of Vehicles with 

a Rear Seat Belt Reminder System at 47. 

211Matthew J. Trowbridge & Richard Kent, RearSeat Motor Vehicle Travel in the U.S.: Using 

National Data to Define a Population at Risk. Am. 

J. Prev. Med. 37(4), at 322 (2009). 

212See FRIA section 4.2, ‘‘Effect of SBWS on Seat 

Belt Use Rates for Rear Seat Occupants.’’ 

213See FRIA table 47. 

214The 3 percent and 7 percent discount rates are 

in accordance with OMB Circular A–4. https://

www.whitehouse.gov/wp-content/uploads/2023/11/ 

CircularA-4.pdf. 

injuries that the final rule requirements 

are aimed at reducing. 

We estimated the benefits resulting 

from the final rule rear seat belt warning 

requirements. The benefits are the 

fatalities and injuries that we estimate 

would be prevented by the finalized 

requirements. The benefits depend, 

principally, on the effectiveness of seat 

belts in preventing deaths and injuries 

and the expected increase in seat belt 

use due to the finalized rear seat belt 

warning system requirements. Seat belt 

effectiveness in mitigating fatalities for 

rear seat occupants 11 years of age and 

older is 56 percent for passenger cars 

and 74 percent for light trucks and 

vans.208

NHTSA believes that the minimum 

required warning signal characteristics 

would be effective at informing the 

driver of the use status of the rear seat 

belts and facilitating the driver to 

request that a rear passenger fasten an 

unfastened belt. A seat belt warning 

system can increase rear seat belt use in 

two ways: it can remind an occupant to 

fasten the occupant’s belt, and it can 

inform the driver that a passenger is 

unbuckled, so that the driver can 

request the occupant fasten the 

occupant’s belt.209 Without a rear seat 

belt warning, the driver must turn 

around to ascertain whether a rear seat 

occupant is using a seat belt (or ask the 

occupant); in some vehicles, belt use 

may not be evident to the driver, even 

if he or she turns around, due to lineof-sight limitations. As noted above, in 

NHTSA’s 2015 survey, 65 percent of 

drivers of vehicles equipped with rear 

seat belt reminders reported that the 

rear seat belt reminder made it easier to 

encourage the rear seat passengers to 

buckle up.210 Also, as noted earlier, 

part-time seat belt users—the 

predominant non-user group—are 

amenable to seat belt warnings. In 

addition, children, who might be 

particularly compliant with driver 

requests, are proportionally much more 

likely to be rear seat passengers than are 

adults.211

We believe that any of the allowable 

rear seat belt reminder systems would 

be effective at accomplishing this goal. 

While some systems provide more 

information than others, and some 

would require the driver to fill in some 

informational gaps, even the most basic 

system (a RSBWS without occupant 

detection) would inform the driver 

about which belts are or are not 

fastened; the driver would readily be 

able to determine whether there were 

any unbelted occupants. We also believe 

that the 60-second visual warning 

would be effective. NHTSA could have 

proposed a more intrusive warning 

signal, such as an audible warning and/ 

or a longer-duration visual warning. 

However, because such warnings 

necessitate occupant detection and we 

are not requiring occupant detection, we 

are also not requiring more aggressive 

warnings. 

NHTSA estimated the effectiveness of 

the rear seat belt warnings. Available 

research regarding seat belt use 

indicates that seat belt warning systems 

are effective at increasing seat belt use; 

however, estimates of the amount of 

increased belt usage that can be 

attributed to warning systems vary. In 

arriving at our estimates of increased 

seat belt usage from SBWS for rear seats, 

we examined current seat belt use rate 

in rear seats and the results of research 

conducted by NHTSA and others on 

percent increase in seat belt use for 

different types of warning systems for 

front seat occupants, as well as 

information submitted in response to 

the request for comments. For rear seat 

passengers 11 years old and older, we 

used a ‘‘low’’ estimate of 3.4 percent 

increase in seat belt use, and a ‘‘high’’ 

estimate of 5.1 percent increase in seat 

belt use. For rear seat passengers from 

six to ten years old, we used a low 

estimate of 0.27 percent and a high 

estimate of 0.41 percent. (The estimated 

increases for younger passengers are 

much lower because they already have 

high rates of seat belt use). For 

simplicity, we refer to these scenarios as 

‘‘Low’’ and ‘‘High.’’ 212

Based on these belt and warning 

system effectiveness estimates, we 

estimate that the rear seat belt warning 

requirements would prevent 26 fatalities 

and 148 injuries annually under the 

‘‘Low’’ scenario. Under the ‘‘High’’ 

scenario, we estimate that 39 fatalities 

and 221 injuries would be prevented 

annually.213 See table 11. Another way 

to measure benefits is by calculating 

equivalent lives saved. Equivalent lives 

saved are the number of prevented 

fatalities added to the number of 

prevented injuries, with the prevented 

injuries expressed in terms of equivalent 

fatalities (that is, with an injury 

expressed as a fraction of a fatality, so 

that the more serious the injury, the 

higher the fraction). The estimated 

equivalent lives saved are presented in 

table 12 at the 3 percent and 7 percent 

discount rate.214

TABLE 11—ESTIMATED ANNUAL BENEFITS—LIVES SAVED AND INJURIES PREVENTED FOR SBWS WITHOUT OCCUPANT

DETECTION (REAR SEATS), WITH ESTIMATED LOW AND HIGH PERCENTAGE POINT INCREASE IN BELT USE

Injury level Low High 

MAIS 1 ..................................................................................................................................................................... 36 54 

MAIS 2 ..................................................................................................................................................................... 80 120 

MAIS 3 ..................................................................................................................................................................... 26 38 

MAIS 4 ..................................................................................................................................................................... 4 6 

MAIS 5 ..................................................................................................................................................................... 1 2 

Total Injuries ..................................................................................................................................................... 148 221 

Fatal .................................................................................................................................................................. 26 39 


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215See FRIA tables 68 and 70. 216The final rule is based on performance 

requirements, and as discussed previously, vehicle 

manufacturers are not restricted to using seat belt 

buckle sensors to determine belt usage. For 

example, spool-out sensors could be used instead 

of seat belt buckle sensors, but for the purposes of 

its compliance test NHTSA will consider a belt to 

be ‘‘not in use’’ when the belt latch is not fastened. 

We assume most manufacturers will likely use 

buckle sensors and that the cost is the same for seat 

belt buckle sensors as for spool-out sensors. 

217See FRIA table 82. 

218See FRIA table 74. 

219National Center for Statistics and Analysis. 

(2021, December). Seat belt use in 2021—Overall 

results (Traffic Safety Facts Research Note. Report 

No. DOT HS 813 241). National Highway Traffic 

Safety Administration. 

TABLE 12—ESTIMATED ANNUAL BENEFITS—EQUIVALENT LIVES SAVED—SBWS WITHOUT OCCUPANT DETECTION (REAR

SEATS) 215

Belt use increase Undiscounted 3 Percent 

discount rate 

7 Percent 

discount rate 

Low .......................................................................................................................................... 36.22 29.98 24.31 

High .......................................................................................................................................... 54.47 45.09 36.55 

We also estimated the costs of the 

finalized requirements. To comply with 

the minimum requirements (a positiveonly system or negative-only/full-status 

system without occupant detection), the 

system would need to have seat belt 

buckle sensors (to determine if the belt 

is fastened) and wiring and wire 

conduits to provide information on the 

belt buckle status from the rear seats to 

the computer processor controlling the 

warning system.216 Based on the results 

of NHTSA’s teardown analysis, we 

estimate a cost of $6.28 per seat. Given 

an average of 3.12 rear seats per vehicle, 

this yields a final cost of $19.59 per 

vehicle. Based on this per-vehicle cost, 

the cost to the fleet to comply with the 

finalized minimum requirements is 

$166.4 million. 

Based on the forgoing, we performed 

benefit-cost and cost-effectiveness 

analyses. A benefit-cost analysis 

calculates net benefits, which is the 

difference between the benefits flowing 

from injury and fatality reductions and 

the cost of the rule. Our net benefit 

estimates are presented in table 13. The 

cost-effectiveness analysis derives the 

cost per equivalent life saved, which is 

equal to the total cost of the rule divided 

by the total fatal equivalents that it 

prevents. These estimates are presented 

in table 14. 

TABLE 13—ANNUAL MONETIZED BENEFITS, COSTS, AND NET BENEFITS—SBWS WITHOUT OCCUPANT DETECTION (REAR

SEATS) 217

[2020 Dollars, in millions] 

Seat belt use increase 

3 percent discount rate 7 percent discount rate 

Benefits Cost Net benefits Benefits Cost Net benefits 

Low ........................................................... $357.78 $166.44 $191.34 $290.05 $166.44 $123.62 

High .......................................................... 538.00 166.44 371.56 436.16 166.44 269.72 

TABLE 14—COST-EFFECTIVENESS ANALYSIS (COST PER EQUIVALENT LIFE SAVED)—SBWS WITHOUT OCCUPANT

DETECTION (REAR SEATS) 218

[2020 Dollars, in millions] 

Seat position & belt use increase ELS Cost Cost/ELS 

3 Percent Discount Rate 

Low .............................................................................................................................................. 29.98 $166.4 $5.55 

High .............................................................................................................................................. 45.09 166.4 3.69 

7 Percent Discount Rate 

Low .............................................................................................................................................. 24.31 $166.4 $6.85 

High .............................................................................................................................................. 36.55 166.4 4.55 

2. Front Seat Belt Warning System 

Based on FARS and CISS data from 

2017 through 2021, on average 8,345 

unrestrained drivers and 1,447 

unrestrained front outboard passengers 

of passenger cars and light trucks were 

killed annually in traffic crashes. 

Additionally, 132,416 unrestrained 

drivers and 25,046 unrestrained front 

outboard passengers were, on average, 

injured annually. After adjusting these 

to account for future decreases in 

fatalities and injuries projected to occur 

in the absence of the finalized 

requirements due to the introduction of 

other mandatory safety technologies 

(e.g., electronic stability control), the 

analysis estimates a baseline of, on 

average, 8,383 fatalities and 150,739 

injuries to unrestrained front seat 

occupants each year. This is the overall 

target population—the annual deaths 

and injuries that the final requirements 

are aimed at reducing. 

According to the NOPUS, 90.6 

percent of drivers used their seat belt in 

2021, and 89.4 percent of passengers in 

the right-front seating position used 

their seat belt.219 To estimate the 

percentage of drivers and front 

passengers who do not always use a seat 

belt, we used the results from a 2004 

analysis using data from the Household 


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220May Chu, ‘‘Statistical brief #62: Characteristics 

of Persons Who Seldom or Never Wear Seat Belts 

2002.’’ https://meps.ahrq.gov/data_files/ 

publications/st62/stat62.pdf. 221Spado, D., Schaad, A., & Block, A. (2019, 

December). 2016 motor vehicle occupant safety 

survey; Volume 2: Seat belt report (Report No. DOT 

HS 812 727). National Highway Traffic Safety 

Administration. 

222Compared to the 2016 MVOSS, which had, 

depending on the question, sample sizes of 

approximately 5,000 to 10,000. 

223For example, the 2016 MVOSS found that 

about 6 percent of drivers reported using their belt 

most of the time or some of the time. See pg. 7 (Fig. 

5) in the MVOSS. 224 Kidd, D.G., and Singer, J. (2019, April) The 

effects of persistent audible seat belt reminders and 

a speed-limiting interlock on the seat belt use of 

drivers who do not always use a seat belt. Insurance 

Institute for Highway Safety, Westat, Inc. 

225There were several limitations in this study, 

the main one being that the number of study 

participants was small, and, consequently, there 

was limited statistical power when comparing the 

change in rate of belt use between the different 

vehicle technology conditions. The study further 

discusses this and other limitations, such as how 

the demographics of the study sample differ from 

part-time belt users nationwide. See also the 

discussion supra, Section VI.B.3. 

Component of the 2002 Medical 

Expenditure Panel Survey (MEPS– 

HC) 220 that found that among persons 

16–64 years of age, 87.7 percent 

reported always or nearly always using 

seat belts when driving or riding in a 

car. Another 6.9 percent reported 

sometimes using seat belts, while 5.4 

percent reported seldom or never using 

seat belts when driving or riding in a 

car. These results are summarized in 

table 15. This means, when an 

observation is made about the 

percentage of drivers who use the seat 

belts, the observed belt use rate is higher 

than 87.7 percent since the other groups 

would contribute to the observed belt 

use rate although they are not always 

using the seat belts. NHTSA recognizes 

that driving habits may or may not have 

changed since 2002 as seat belt use rates 

have increased and as new generations 

of drivers and passengers are on the 

road. NHTSA considered, but 

tentatively decided not to use, the 

results of more recent studies, such as 

the (2016) Motor Vehicle Occupant 

Safety Survey (MVOSS) 221 to estimate 

the percentage of drivers and front 

passengers who do not always use a seat 

belt. While the 2016 MVOSS is more 

recent, we decided to use the 2004 

study because we tentatively concluded 

that the data provided by the 2004 study 

best suited the needs of our analysis. 

Although most data on seat belt use is 

self-reported, including the data in the 

2004 study, the 2004 study has a high 

sample size (approximately 25,000) 222

and provides robust categorizations of 

seat belt use that fit the needs of our 

analysis. Furthermore, when comparing 

this data to the findings of the 2016 

MVOSS, we did not find evidence that 

seat belt use trends have significantly 

changed over time.223

TABLE 15—SEAT BELT USE CHARACTERISTICS

Belt user and related items Rate 

(percent) 

Reported ‘‘sometimes using seat belts’’ .............................................................................................................................................. 6.9 

Reported ‘‘seldom or never using seat belts when driving or riding in a car’’ .................................................................................... 5.4 

Reported always use seat belts .......................................................................................................................................................... 87.7 

Total .............................................................................................................................................................................................. 100.0 

As we did for the rear seats, NHTSA 

estimated the effectiveness and benefits 

associated with requiring a seat belt 

warning system that remains activated 

until the seat belts are buckled for the 

driver and front outboard passenger 

seats. In developing this estimate, 

NHTSA used the results of a 2019 study 

conducted by IIHS by Kidd et al.224 In 

the Kidd et al. (2019) study, part-time 

belt users (who had a recent seat belt 

citation and reported not always using 

a seat belt) drove two vehicles for a 

certain period of time, a Chevrolet with 

three intermittent 7-second audible 

warnings followed by either a BMW 

with a 100-second audible warning 

(n=17) or a Subaru with an audible 

warning that continues until the seat 

belt is buckled (n=16). (All of the 

vehicles provided a visual warning that 

lasted until the seat belt was buckled.) 

Kidd et al. found that, relative to the 

intermittent reminder (i.e., 7-second 

audible reminder), the BMW warning 

with the 100-second audible reminder 

increased seat belt use by 30 percent 

and the Subaru warning with the 

indefinite audible warning increased 

belt use by 34 percent.225 The Kidd 

Study also found that some participants 

circumvented the enhanced warning 

systems by misusing the seat belt 

(sitting on a buckled seat belt or routing 

the buckled seat belt behind their back). 

Hard core ‘‘never users’’ of seat belts 

may similarly choose to circumvent the 

enhanced seat belt warning system. 

Therefore, NHTSA assumed that the 

‘‘never and seldom users’’ of seat belts 

(5.4 percent from the Chu study) could 

potentially circumvent the enhanced 

SBWS, so the analysis conservatively 

assumes no increase in seat belt use 

with enhanced SBWS for ‘‘never and 

seldom users.’’ 

NHTSA also reviewed manufacturer 

data for MY 2020 vehicles to determine 

the market penetration of seat belt 

warning systems of various durations in 

the front outboard seats and obtained 

the estimates in table 16. 

TABLE 16—MARKET PENETRATION OF DIFFERENT DURATION SEAT BELT AUDIBLE WARNING SYSTEMS

SBWS system Percentage 

of sales 

<90 second warning ............................................................................................................................................................................ 7.6 

90 second and 90+ but not indefinite .................................................................................................................................................. 85.2 

Enhanced—Warning until seat belt is buckled .................................................................................................................................... 7.2 


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226See FRIA table 31. 

227See FRIA table 32. 

228The final rule differs from the proposed 

indefinite audio-visual warning on vehicle start-up, 

because while the visual warning will be indefinite 

it is no longer specific to the ‘‘start-of-trip’’ and the 

audible warning will only be required to activate for 

at least 30 seconds and after the 30 seconds it will 

be a speed-initiated indefinite audible warning. 

However, in the benefits and costs sections we will 

continue to refer to the front seat belt warning 

system as an indefinite warning because both the 

audible and visual warnings will be required to be 

active until the seat belt is fastened, if the 

respective trigger criteria are met. 

229See FRIA table 60. 

230See FRIA table 73. 

231See FRIA, tables 80, 81, and 82. 

For drivers, seat belts reduce the risk 

of fatality by 48 percent (for passenger 

cars) and 61 percent (for light trucks and 

vans) and reduce the risk of moderate to 

greater severity injuries by up to 65 

percent.226 For front outboard 

passengers, seat belts reduce the risk of 

fatality by 37 percent (for passenger 

cars) and by 58 percent (for light trucks 

and vans) and reduce the risk of 

moderate to greater severity injuries by 

65 percent.227

Based on the estimated seat belt 

warning system effectiveness in 

increasing seat belt use, the market 

penetration of different duration seat 

belt audible warning systems, and the 

effectiveness of seat belts in mitigating 

fatalities and injuries, NHTSA estimates 

that requiring an audio-visual seat belt 

warning 228 that remains activated until 

the seat belt is buckled (indefinite 

duration) would prevent 20 driver 

fatalities, 2 front outboard passenger 

fatalities, and a total of 395 injuries 

annually, as shown in table 17. This 

rule results in 46.7 undiscounted 

equivalent lives saved, as shown in 

table 18. The estimated discounted 

annual benefits in terms of equivalent 

lives saved are also shown in table 18. 

TABLE 17—ESTIMATED ANNUAL BENEFITS—LIVES SAVED AND INJURIES PREVENTED—INDEFINITE SBWS (FRONT

OUTBOARD SEATS) 229

Injury level Driver Front passenger Total 

MAIS 1 ................................................................................................................................... 129 14 143 

MAIS 2 ................................................................................................................................... 151 19 170 

MAIS 3 ................................................................................................................................... 62 8 69 

MAIS 4 ................................................................................................................................... 9 1 10 

MAIS 5 ................................................................................................................................... 3 0 3 

Total Injuries ................................................................................................................... 354 42 395 

Fatal ....................................................................................................................................... 20 2 22 

Note: Values may not sum due to rounding. 

TABLE 18—ESTIMATED ANNUAL BENEFITS—EQUIVALENT LIVES SAVED—INDEFINITE SBWS (FRONT OUTBOARD

SEATS) 230

Undiscounted 3 Percent 

discount rate 

7 Percent 

discount rate 

Driver ........................................................................................................................................... 42.26 34.98 28.36 

Front Passenger .......................................................................................................................... 4.44 3.68 2.99 

Total ...................................................................................................................................... 46.70 38.66 31.35 

We also estimated the costs of the 

finalized requirements. Since all driver 

seats are already required to have at 

least the basic warning system, the 

incremental cost of enhanced seat belt 

warning for the driver seat is zero. We 

assume there would be some labor costs 

associated with software updates 

needed to extend the warning. However, 

as this is a simple programming change, 

this cost would be amortized over each 

vehicle’s production and is therefore 

considered de minimis. Though there 

are no current requirements for a seat 

belt warning system for the front 

outboard passenger seat, NHTSA 

estimates that 96 percent of vehicles 

have seat belt warning systems on the 

front outboard passenger seat. NHTSA 

estimated the cost of equipping a seat 

belt warning system in the front 

outboard passenger seat to be $2.13 per 

seat. Therefore, the cost of equipping 

the remaining 4 percent of the 16 

million new vehicle fleet is $1.36 

million (= 16 million × 4 percent × 

$2.13). 

Based on the foregoing, we performed 

benefit-cost and cost-effectiveness 

analyses. The estimated net benefits, 

based on a 3 percent and 7 percent 

discount, are presented in table 19 and 

the cost-effectiveness estimates are 

presented in table 20. 

TABLE 19—ANNUAL MONETIZED BENEFITS, COSTS AND NET BENEFITS—INDEFINITE SBWS (FRONT OUTBOARD

SEATS) 231

[2020 Dollars, in millions] 

Driver Front passenger Driver and front passenger 

3 Percent 7 Percent 3 Percent 7 Percent 3 Percent 7 Percent 

Passenger car Benefits ............................ $188.89 $154.12 $22.86 $18.65 $211.75 $172.77 

Light Truck & Van Benefits ...................... 228.51 184.29 21.05 16.97 249.56 201.26 


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232See FRIA, table 74. 233See FRIA, table 82. 234See FRIA, table 74. 

TABLE 19—ANNUAL MONETIZED BENEFITS, COSTS AND NET BENEFITS—INDEFINITE SBWS (FRONT OUTBOARD

SEATS) 231—Continued 

[2020 Dollars, in millions] 

Driver Front passenger Driver and front passenger 

3 Percent 7 Percent 3 Percent 7 Percent 3 Percent 7 Percent 

Total Benefits .................................... 417.41 338.41 43.90 35.62 461.31 374.03 

Total Costs ........................................ 0 0 1.36 1.36 1.36 1.36 

Net Benefits ............................................. 417.41 338.41 42.54 34.26 459.95 372.67 

TABLE 20—COST-EFFECTIVENESS ANALYSIS (COST PER EQUIVALENT LIFE SAVED)—INDEFINITE SBWS (FRONT

OUTBOARD SEATS) 232

[2020 Dollars, in millions] 

Discount rate ELS Cost Cost/ELS 

3 percent ...................................................................................................................................... 38.66 $1.36 $0.04 

7 percent ...................................................................................................................................... 31.35 $1.36 $0.04 

3. Overall Benefits and Costs of the 

Final Rule 

In table 21, we combine the benefits 

and costs for the finalized rear and front 

seat belt warning requirements. We 

estimate positive net benefits under all 

discount rates and effectiveness 

estimates. 

TABLE 21—NET BENEFITS FROM THE FINAL RULE (SBWS FOR REAR SEATING POSITIONS AND INDEFINITE SBWS FOR

FRONT OUTBOARD SEATING POSITIONS) 

[2020 Dollars, in millions] 233

3 Percent 

discount rate 

7 Percent 

discount rate 

Front Outboard Seats .............................................................................................................................................. $459.95 $372.67 

Rear Seats ...............................................................................................................................................................

(low increase in rear seat belt use) ......................................................................................................................... 191.34 123.62 

Rear Seats ...............................................................................................................................................................

(high increase in rear seat belt use) ....................................................................................................................... 371.56 269.72 

Total Net Benefits .............................................................................................................................................

(low increase in rear belt use) .......................................................................................................................... 651.29 496.28 

Total Net Benefits .............................................................................................................................................

(high increase in rear belt use) ........................................................................................................................ 831.51 642.39 

In table 22, we combine the 

equivalent lives saved and cost for the 

finalized rear and front seat belt 

warning requirements to determine the 

cost per equivalent life saved. 

TABLE 22—COST PER EQUIVALENT LIVES SAVED FROM THE FINAL RULE (SBWS FOR REAR SEATING POSITIONS AND

INDEFINITE SBWS FOR FRONT OUTBOARD SEATING POSITIONS) 234

[2020 Dollars, in millions] 

Category 

Discounted at 3 percent Discounted at 7 percent 

Equivalent 

Lives Saved Cost 

Cost per 

Equivalent 

Live Saved 

Equivalent 

Lives Saved Cost 

Cost per 

Equivalent 

Live Saved 

Rear Seat: 

Low ............................................................... 29.98 $166.44 $5.55 24.31 $166.44 $6.85 

High ............................................................... 45.09 3.69 36.55 4.55 

Front Seat ............................................................ 38.66 1.36 0.04 31.35 1.36 0.04 

Total:.

Low ........................................................ 68.65 167.8 2.44 55.66 167.8 3.01 

High ....................................................... 83.75 2.00 67.90 2.47 


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235The rear seat occupant detection in current 

vehicles is likely only able to detect a 5th percentile 

female and heavier occupants, but not children who 

weigh less than the 5th percentile female as is 

required for rear seat occupant detection in this 

final rule. 

236See FRIA, table 119. 

237See FRIA, tables 134 and 138. 

B. Regulatory Alternatives 

In the preceding sections of this 

document, we discussed various 

alternatives for different aspects of the 

finalized requirements. We quantified 

the costs and benefits of three of these 

alternatives (rear-seat occupant 

detection, a 90-second front outboard 

seat belt warning, and front center seat 

belt warning). Below, we briefly 

summarize our results. For a more 

detailed discussion, the reader is 

referred to the Final Regulatory Impact 

Analysis in the docket for this 

rulemaking. 

1. Occupant Detection in Rear Seats 

For the rear seat belt reminder, 

NHTSA is not requiring occupant 

detection in the rear seats but permits 

occupant detection in rear seats. As a 

regulatory alternative, NHTSA 

estimated the costs and benefits of 

requiring a SBWS with occupant 

detection in the rear seats. 

NHTSA’s teardown analysis indicates 

that occupant detection components 

cost $39.75 per vehicle, which, added to 

the $19.59 per vehicle cost of the buckle 

sensor, results in a combined warning 

system cost of $59.33 per vehicle (2020 

$). NHTSA estimates that about 47 

percent of new vehicles have a SBWS 

for the rear seating positions and 7 

percent of new vehicles have occupant 

detection in rear seats. If NHTSA 

selected the regulatory alternative that 

required occupant detection, this rule 

would result in a total cost of $802 

million. As with the final rule, this cost 

estimate assumed that 53 percent of new 

vehicles would need to install a seat belt 

sensor in the rear seats. And as 

discussed, rear seat occupant detection 

systems would need to be installed in 

all new vehicles. Although seven 

percent of light vehicles already have 

rear seat occupant detection, those 

SBWSs may not meet the requirements 

specified in this regulatory 

alternative.235 As a result, this analysis 

accounts for the cost of adding occupant 

detection in the rear seats in all new 

light vehicles to comply with this 

regulatory alternative. The total cost for 

this regulatory alternative is about $802 

million.236

Because there is uncertainty in how 

much more effective a SBWS with 

occupant detection would be in 

increasing seat belt use compared to the 

already estimated increase in seat belt 

use with SBWSs without occupant 

detection, NHTSA did not conduct a 

cost-effectiveness and net benefits 

analysis. Instead, NHTSA estimated the 

minimum increase in seat belt use for 

this regulatory alternative that would 

result in overall benefits equal to the 

overall costs (zero net benefits). 

Furthermore, for a direct comparison to 

the final rule requirements, NHTSA also 

considered how much greater the 

benefits from this regulatory alternative 

would have to be for the net benefits to 

be equal to those from the final rule, 

which does not require occupant 

detection. 

The agency estimated that seat belt 

use for rear seat occupants 11 years and 

older would have to increase by 

approximately 5.4 percent when 

discounted at 3 percent and 6.7 percent 

when discounted at 7 percent for this 

regulatory alternative to result in zero 

net benefits. Moreover, for this 

regulatory alternative to match the net 

benefits (taking into account the Low 

and High estimates of increased seat belt 

usage) from the final rule, seat belt use 

for rear seat occupants 11 years and 

older would have to increase by 7.8 to 

9.0 percent when discounted at 3 

percent, and by 9.1 to 10.2 percent 

when discounted at 7 percent. 

Under the final rule, which does not 

require occupant detection, seat belt use 

for rear seat occupants 11 years and 

older is estimated to increase from 75.12 

percent to approximately 76.93 percent 

in the Low estimate and 77.84 percent 

in the High estimate. These increases 

reflect an approximately 2.4 percent and 

3.6 percent increase in seat belt use 

under the final rule. 

Therefore, in this regulatory 

alternative requiring occupant detection 

for the rear seats, SBWS for rear seat 

occupants would need to be 

approximately 2.5 to 3.8 times more 

effective than the final rule at increasing 

seal belt usage to generate the same 

level of net benefits as the final rule. 

The SBWSs considered under this 

regulatory alternative are capable of 

informing the driver either which 

occupants are not using their seat belts 

or how many of the rear seat occupants 

are not using their seat belts. While we 

would expect some possible increase in 

seat belt use from that specific 

functionality, it is doubtful that it would 

double to quadruple the increase in seat 

belt use estimated for SBWSs without 

occupant detection. Therefore, based on 

the available information, the agency 

did not choose this regulatory 

alternative. 

2. 90-Second Front Outboard Seat Belt 

Warning 

NHTSA also estimated the costs and 

benefits if it were to require a 90-second 

audio-visual warning for the front 

outboard seats instead of the finalized 

requirement for a warning that lasts 

until the belt and any occupied seat is 

buckled. NHTSA estimated the benefits 

in a similar manner as that for the 

finalized seat belt warning for front seat 

occupants where the warning remains 

on until the seat belt is buckled. The 

main difference is that this alternative 

only affects the 7.6 percent of the 

vehicle fleet with a front seat occupant 

seat belt warning with duration less 

than 90 seconds. 

The benefits of this alternative are 

presented in table 23.237

TABLE 23—INJURIES PREVENTED, LIVES SAVED, AND EQUIVALENT LIVES SAVED IN FRONT OUTBOARD SEATS BY A 90 

SECOND DURATION SBWS 

Injury Level 

Injuries and Fatalities Prevented Equivalent Lives Saved 

Driver Front Passenger Driver Front Passenger 

MAIS 1 ................................................................................................. 43 4.7 0.19 0.02 

MAIS 2 ................................................................................................. 44 5.7 1.82 0.23 

MAIS 3 ................................................................................................. 18 2.3 3.26 0.41 

MAIS 4 ................................................................................................. 3 0.3 0.83 0.08 

MAIS 5 ................................................................................................. 1 0.1 0.47 0.05 

Fatal ..................................................................................................... 6 0.6 6.07 0.57 

Total .............................................................................................. ........................ .............................. 12.66 1.37 


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238See FRIA, tables 142 and 143. 239See FRIA, table 122. 

About 14 equivalent lives are saved 

by this alternative, which is 

significantly lower than the nearly 47 

equivalent lives saved by a warning that 

remains on until the seat belt is buckled. 

The cost of this alternative is the same 

as that for the warning required by this 

final rule. The only cost is that for the 

4 percent of vehicles without a seat belt 

warning system in the front outboard 

passenger seat (cost = $1.36 million). 

The annual monetized benefits, costs, 

and net benefits of this alternative are 

shown in table 24. 

TABLE 24—ANNUAL MONETIZED BENEFITS, COSTS AND NET BENEFITS FOR A 90 SECOND DURATION SBWS IN FRONT

OUTBOARD SEATS 238

[2020 Dollars, in millions] 

Driver Front Passenger Driver and Front 

Passenger 

3 Percent 7 Percent 3 Percent 7 Percent 3 Percent 7 Percent 

Passenger car Benefits .................................................... $58.69 $47.89 $7.25 $5.92 $65.94 $53.81 

Light Truck & Van Benefits .............................................. 66.34 53.50 6.25 5.04 72.59 58.54 

Total Benefits ............................................................ 125.03 101.39 13.50 10.96 138.54 112.35 

Total Costs ....................................................................... 0 0 1.36 1.36 1.36 1.36 

Net Benefits .............................................................. 125.03 101.39 12.14 9.59 137.18 110.99 

While this regulatory alternative has 

positive net benefits, the benefits and 

net benefits are significantly lower than 

the indefinite duration SBWS for front 

seat occupants in the final rule (net 

benefits of $459.95 million and $372.67 

million when discounted to 3 and 7 

percent, respectively). 

3. Seat Belt Warning for Front Center 

Seat 

The agency also considered requiring 

a seat belt warning system for the front 

center seating position. To estimate 

incremental benefits, NHTSA used the 

2017–2021 FARS data and CISS data, 

and the adjustment factors to account 

for safety impacts of new required safety 

technologies to establish the target 

population addressed by this regulatory 

alterative (Table 25). 

TABLE 25—ANNUAL ADJUSTED FATALITIES AND NON-FATAL INJURIES TO FRONT CENTER SEAT PASSENGERS 239

Injury severity Restrained Unrestrained Total 

MAIS 1 ......................................................................................................................................... 190 100 290 

MAIS 2 ......................................................................................................................................... 0 0 0 

MAIS 3 ......................................................................................................................................... 0 0 0 

MAIS 4 ......................................................................................................................................... 0 0 0 

MAIS 5 ......................................................................................................................................... 0 0 0 

Total Injuries .........................................................................................................................

(MAIS 1–5) ........................................................................................................................... 190 100 290 

Fatal ............................................................................................................................................. 6 13 19 

Due to a lack of data, NHTSA is 

unable to establish the seat belt use rate 

for front center passengers under the 

baseline. As front center seat passengers 

are most similar to front outboard 

passengers, this analysis makes use of 

the established seat belt use rate for 

front outboard passengers to establish 

the baseline seat belt use rates for front 

center seat occupants. Based on the 

2021 NOPUS data, the baseline seat belt 

use rate is 89.40 percent and the 

corresponding seat belt use rate in 

potentially fatal crashes is 76.88 

percent. 

In order to estimate the change in seat 

belt use for front center seat passengers 

as a result of the SBWS, this analysis 

makes use of the linear regression model 

used to estimate the impact of the SBWS 

on the seat belt use rates of rear seat 

occupants. Under this regulatory 

alternative, the seat belt use rate for 

front center seat passengers using the 

high estimate is 91.58 percent and the 

corresponding seat belt use rate in 

potentially fatal crashes is 79.69 

percent. 

The cost for front center passenger 

seats would include the cost for a 

buckle sensor and occupant detection. 

Therefore, the cost per vehicle for this 

regulatory alternative is $14.86 in 2020 

dollars. This cost estimate reflects a cost 

of $2.13 to add a buckle sensor and the 

cost to add occupant detection of 

$12.73. 

In assessing the number of vehicles 

that would be impacted by this 

regulatory alternative, we consider that 

the front center seat is not a common 

feature in new light vehicles. Based on 

our engineering judgement, we expect 

that approximately 800,000 vehicles or 

5 percent of the new vehicle fleet 

include a center seating position. Table 

26 presents the total cost to meet the 

requirements under this regulatory 

alternative for an indefinite duration 

SBWS for front center passenger seats. 


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240See FRIA, table 128. 

241See FRIA, tables 129 and 130. 

242 88 FR 61674. This figure is based on data on 

total projected vehicle sales in the United States for 

MY 2022 from the agency’s New Car Assessment 

Program Purchasing with Safety in Mind: What to 

Look For When Buying a Vehicle program. 

TABLE 26—TOTAL COST OF INDEFINITE DURATION SBWS FOR FRONT CENTER PASSENGER SEATS 240

Number of vehicles impacted Per vehicle cost Total cost 

800,000 $14.86 $11,888,000 

Table 27 presents the of the costeffectiveness analysis and table 28 

presents the benefit-cost analysis for 

this regulatory alternative.241 When 

discounted at three and seven percent, 

the cost per ELS is approximately $40.9 

million and $50.6 million, respectively 

and the net benefits are negative for this 

regulatory alternative. Because the cost 

per ELS is higher than the 

comprehensive cost of a fatality and the 

net benefits are negative, this regulatory 

alternative is not cost-effective. 

TABLE 27—COST-EFFECTIVENESS ANALYSIS FOR SBWS FRONT CENTER SEAT PASSENGERS

[Millions] 

Category 

Discounted at 3 percent Discounted at 7 percent 

Equivalent 

lives saved Cost 

Cost per 

equivalent live 

saved 

Equivalent 

lives saved Cost 

Cost per 

equivalent live 

saved 

Front Center Seat .................................... 0.29 $11.89 $40.91 0.23 $11.89 $50.63 

TABLE 28—BENEFIT-COST ANALYSIS FOR SBWS FRONT CENTER SEAT PASSENGERS

[Millions] 

Category 

Discounted at 3 percent Discounted at 7 percent 

Monetized 

benefits Cost Net benefits Monetized benefits Cost Net benefits 

Front Center Seat .................................... $3.47 $11.89 ¥$8.42 $2.80 $11.89 ¥$9.09 

IX. Compliance Dates 

NHTSA proposed that vehicles be 

required to comply with the 

requirements of this rule the first 

September 1 that is one year after the 

publication of the final rule for the front 

seat belt warning system requirements 

and the first September 1 that is two 

years after the publication of the final 

rule for the rear seat belt warning 

system requirements, with optional 

early compliance permitted. Consistent 

with 49 CFR 571.8(b), multi-stage 

manufacturers and alterers would have 

an additional year to comply. 

We estimated it would take two years 

for manufacturers to equip their 

vehicles with the necessary 

technologies, redesign hardware and 

software components, and validate their 

systems to comply with the 

requirements for the rear seat belt 

reminder systems. Regarding front 

passenger outboard seat belt warning 

requirements, we noted that because of 

the market penetration of such systems 

(96 percent of new vehicles), the 

majority of vehicle manufacturers 

would simply have to make software 

adjustments necessary to ensure they 

meet the proposed requirements.242

Comments 

The National Transportation Safety 

Board (NTSB) supported the proposed 

lead time and emphasized the timeline 

of this rulemaking activity related to 

seat belt warning systems. 

Several commenters suggested shorter 

lead times. MADD and Advocates and 

Public Citizen supported a compliance 

deadline as soon as is feasible. MADD 

stated that given the state and 

availability of current technology, a oneyear deadline for compliance is likely 

reasonable. Advocates and Public 

Citizen stated that one year should be 

sufficient for rear systems, noting that 

IIHS testing has demonstrated that this 

deadline is achievable and that delaying 

will cost lives. 

SRN commented that, depending on 

the date on which the final rule is 

published, the rear seat compliance 

deadline could be closer to 3 years, and 

urged NHTSA to ensure that compliance 

is required within close to a 2-year 

window. 

IIHS and NAMIC commented that the 

requirements should be implemented 

immediately. IIHS noted research 

suggesting that increasing seat belt use 

of unbuckled occupants throughout the 

vehicle by up to 34 percent would save 

about 1,600 lives each year (Kidd & 

O’Malley, 2023), and that delaying the 

implementation of the upgraded 

standard would unnecessarily delay its 

life-saving benefits. IIHS explained that 

according to its evaluations, since 2022 

adoption of rear reminder systems has 

increased and manufacturers have 

responded quickly in the past to their 

requirements, suggesting that less lead 

time is needed. 

Consumer Reports agreed with IIHS 

that manufacturers have demonstrated 

they can make improvements quickly 

and suggested that both rear and front 

reminders be required within 1 year. 

They also noted that in 2012, Congress 

mandated that NHTSA issue a final rule 

by 2015, and that the ANPRM for this 

rulemaking was published in 2019. 

They argued that given this timeline, 

compliance should be required sooner. 

Other commenters requested that the 

compliance dates be extended. Auto 

Innovators contended that the proposed 

lead time is not reasonable or practical 

for implementing the proposed changes. 


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243While the final rule requires that the visual 

warning must not be overridden by other visual 

warnings, it does allow the audible warning to be 

paused during the activation of another audible 

safety warning that is designed to alert the driver 

to take immediate action; in this case, however, the 

seat belt audible warning must be resumed for the 

remainder of the required duration after the other 

audible warning deactivates. 

In particular, they emphasized that the 

lack of harmonization with ECE R16 

may result in design changes for 

vehicles that are in the final stages of 

preproduction and manufacturers may 

no longer be able to use hardware and 

software systems currently deployed in 

other markets. Honda provided a list of 

changes that it would undertake to meet 

the requirements proposed in the NPRM 

and suggested that the lead time 

proposed is inadequate to accomplish 

them. 

Nissan also requested additional lead 

time, especially if it is necessary to 

relocate the front outboard passenger 

telltale. Auto Innovators and Honda 

noted that if NHTSA harmonized the 

rule further with ECE R16, less lead 

time would be needed to meet the 

requirements. 

Auto Innovators, HATCI, Ford, and 

Honda requested a synchronized twoyear phase-in for both the front and rear 

row seating position requirements that 

begins three years after publication of 

the final rule. In their proposal, a set 

percentage of vehicles would be 

required to meet the requirements of the 

rule beginning the first September 1st 

that is at least 3 years after publication 

of the final rule; a higher percentage by 

the first September 1st after 4 years; 

with full compliance by the first 

September 1st that is at least five years 

after publication of the final rule. 

HATCI specified that the first phase-in 

threshold should be no more than 50 

percent of vehicles. Ford and Honda 

emphasized that this approach would 

allow manufacturers to account for 

differences in implementation across 

models with varied development cycles. 

Auto Innovators and Honda argued that 

this approach would unify the lead time 

for front and rear systems because there 

would not be a benefit to having 

different lead times for front and rear 

systems due to the limitations of 

production schedules. Auto Innovators 

commented that there is no benefit or 

regulatory relief provided by NHTSA’s 

proposal for one year of lead time for 

the front and two years for the rear 

because it is both highly impractical and 

unlikely that manufacturers will be able 

to adjust production schedules to 

account for changes to the front row and 

rear row seating positions 

independently of each other, and only 

one year apart. Additionally, some 

commenters, such as Auto Innovators 

and Nissan, commented that if the rule 

does not allow for the reminder to be 

overridden, it will likely result in the 

need for significant changes to the 

instrument cluster that will require 

additional time and resources to 

implement. Nissan commented that 

additional lead time becomes more 

critical if relocating the front outboard 

passenger telltale indicator beyond the 

vehicle’s current meter display is 

required. 

A few commenters, such as Auto 

Innovators and Consumer reports, 

requested that optional early 

compliance be allowed. 

Auto Innovators urged the agency to 

announce whether the lead time will be 

changed through the docket, other such 

notice, or to publish a second NPRM 

within one year of its original filing, to 

ensure that manufacturers do not waste 

time, money, and effort to develop 

products that align with the proposal, 

but which need to be changed to meet 

the final rule. 

Agency Response 

NHTSA is finalizing the compliance 

dates as proposed in the NPRM. These 

dates properly balance the practical 

realities of bringing systems into 

compliance with maximizing the safety 

benefits of this rule. We are allowing 

optional early compliance. 

NHTSA disagrees with commenters 

who argue that compliance can be 

required immediately or who seek to 

shorten the compliance timeline. 

NHTSA understands that any allowed 

time to bring systems into compliance 

risks reducing some of the benefits of 

the rule. However, we must balance 

maximizing effectiveness with 

considerations of feasibility and 

practicability. Although commenters 

correctly point out that the necessary 

technologies for both front and rear 

systems are available, they 

underestimate the time some 

manufacturers may need to integrate 

components into vehicles for the rear 

seat reminder as well as incorporate 

visual signals and validate system 

performance for both front and rear 

positions. Although some manufacturers 

may have been able to rapidly adapt 

their systems to changes in IIHS ratings, 

this fact does not support the notion 

that doing so would be practicable for 

the entire industry. For example, a small 

number of vehicles do not yet have 

voluntary front passenger seat belt 

warnings, and these vehicles would 

need hardware integration. We also 

disagree with NAMIC and Consumer 

Reports that the duration of this 

rulemaking effort warrants shortening 

the date schedule. Our determination 

regarding the proper compliance dates 

is based on current information and 

when the rule is finalized. The option 

of early compliance may realize earlier 

safety benefits for vehicles with earlier 

development schedules. 

NHTSA also disagrees with 

commenters seeking to extend the dates. 

In particular, a three-year compliance 

date with a two-year phase-in, suggested 

by Auto Innovators, HATCI, Honda, and 

Ford, dramatically exceeds the amount 

of time that manufacturers should need 

to implement the changes required by 

this rule. As noted, the technology for 

these systems already exists. For front 

systems in particular, the vast majority 

of vehicles already incorporate the 

necessary technology, and only software 

changes will be needed to bring systems 

into compliance. 

Additionally, we have made changes 

from the NPRM which should 

significantly reduce the time needed to 

bring systems into compliance. For 

example, this final rule no longer 

dictates specific compliance options for 

the information conveyed by the rear 

seat belt warning visual warning; the 

finalized requirements for the visual 

warning allow all of the systems that 

would have been allowed under the 

proposed rule, as well as additional 

systems that would not have been 

allowed under the proposed rule, such 

as a negative-only system without 

occupant detection and a full-status 

system without occupant detection. It 

also does not require the front passenger 

seat belt visual warning to be visible to 

the front passenger (except for certain 

ADS-equipped vehicles), which was an 

element of the proposal about which 

certain commenters, such as Nissan, 

expressed significant cost and time 

concerns. Indeed, in the NPRM we 

sought comment, and received no 

detailed comments, regarding which 

types of vehicles might need additional 

lead time to accommodate the proposed 

visibility requirement. Additionally, 

Auto Innovators noted that less time 

would be needed to implement 

requirements that harmonize with ECE 

R16. We have also incorporated changes 

from the NPRM which increase 

harmonization with ECE R16 

significantly. Finally, we do not believe 

it is necessary to grant additional time 

to accommodate that warnings are not 

allowed to be overridden because this 

rule provides a large amount of 

flexibility for manufacturers to design 

and locate the visual alerts to resolve 

this issue.243 Because these elements 

resolve many of the concerns raised by 


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244 49 CFR, Part 5, Subpart B; Department of 

Transportation Order 2100.6A, Rulemaking and 

Guidance Procedures, June 7, 2021. 245H.R. 3684 (117th Congress) (2021). 

commenters about the compliance 

timeline, we are not extending the 

compliance dates. 

We are also not implementing a 

unified lead time for front and rear 

systems. As we pointed out in the 

NPRM, 96 percent of vehicles already 

have a front outboard passenger seat belt 

warning system, while market 

penetration for rear systems is much 

lower. The acquisition and integration 

of additional hardware for rear seats, 

which is not needed for the vast 

majority of front passenger systems, 

warrants additional lead time for the 

rear systems. 

Finally, because we are not changing 

the lead time from the proposal, we are 

not publishing the notice of changes 

regarding the lead time requested by 

Auto Innovators. 

X. Regulatory Analyses 

Executive Order 12866, Executive Order 

14094, Executive Order 13563, and DOT 

Regulatory Policies and Procedures 

NHTSA has considered the impact of 

this rule under Executive Order 12866, 

Executive Order 14094, Executive Order 

13563, DOT Order 2100.6A, and the 

Department of Transportation’s 

regulatory policies and procedures.244

The Office of Management and Budget 

determined that this rule is a significant 

regulatory action and was reviewed 

under Section 3(f)(1) of E.O. 12866, as 

amended by E.O. 14094. Pursuant to 

E.O. 12866 and the Department’s 

policies, we have identified the problem 

this rule addresses, assessed the benefits 

and costs, and considered alternatives. 

These analyses have been summarized 

in Section VII, Regulatory Alternatives 

and Section VIII, Overview of Benefits 

and Costs and are discussed in more 

detail in the docketed final regulatory 

impact analysis. 

Promoting International Regulatory 

Cooperation 

The policy statement in section 1 of 

Executive Order 13609 provides that the 

regulatory approaches taken by foreign 

governments may differ from those 

taken by the United States to address 

similar issues, and that in some cases 

the differences between them might not 

be necessary and might impair the 

ability of American businesses to export 

and compete internationally. It further 

recognizes that in meeting shared 

challenges involving health, safety, and 

other issues, international regulatory 

cooperation can identify approaches 

that are at least as protective as those 

that are or would be adopted in the 

absence of such cooperation and can 

reduce, eliminate, or prevent 

unnecessary differences in regulatory 

requirements. 

In addition, section 24211 of the 

Infrastructure, Investment, and Jobs Act 

(IIJA; Pub. L. 117–58), Global 

Harmonization, provides that DOT 

‘‘shall cooperate, to the maximum 

extent practicable, with foreign 

governments, nongovernmental 

stakeholder groups, the motor vehicle 

industry, and consumer groups with 

respect to global harmonization of 

vehicle regulations as a means for 

improving motor vehicle safety.’’ 245

As discussed in Section VII and 

through this preamble, this rule 

harmonizes with ECE R16, Euro NCAP, 

and the IIHS protocol as much as 

possible, but deviates where we 

believed it was justified with respect to 

the Safety Act criteria (need for safety, 

objectivity, and practicability). The 

reasons for following or deviating in any 

of these respects are explained in detail 

in the relevant section of the preamble. 

In general, we believe that although this 

rule deviates from these requirements or 

protocols in some ways, it is not 

incompatible with them, so that it is 

possible to design a seat belt reminder 

system that complies with both this rule 

and protocols such as R16. Further, 

almost all international NCAP programs, 

including those in Europe, Japan, China, 

Korea, Latin America, Southeast Asia, 

and Australia and New Zealand, award 

points to vehicles that are equipped 

with seat belt warning systems for 

passenger seating positions. Thus, the 

requirements in this rule are consistent 

with these international programs and 

complement those international efforts 

to increase seat belt use by all vehicle 

occupants. 

Regulatory Flexibility Act 

Pursuant to the Regulatory Flexibility 

Act (5 U.S.C. 601 et seq., as amended by 

the Small Business Regulatory 

Enforcement Fairness Act (SBREFA) of 

1996), whenever an agency is required 

to publish an NPRM or final rule, it 

must prepare and make available for 

public comment a regulatory flexibility 

analysis (RFA) that describes the effect 

of the rule on small entities (i.e., small 

businesses, small organizations, and 

small governmental jurisdictions). The 

Small Business Administration’s 

regulations at 13 CFR part 121 define a 

small business, in part, as a business 

entity ‘‘which operates primarily within 

the United States.’’ 13 CFR 121.105(a). 

No regulatory flexibility analysis is 

required if the head of an agency 

certifies that the rule will not have a 

significant economic impact on a 

substantial number of small entities. 

SBREFA amended the Regulatory 

Flexibility Act to require Federal 

agencies to provide a statement of the 

factual basis for certifying that a rule 

will not have a significant economic 

impact on a substantial number of small 

entities. 

I certify that this final rule would not 

have a significant economic impact on 

a substantial number of small entities. 

According to 13 CFR 121.201, the Small 

Business Administration’s size 

standards regulations used to define 

small business concerns, manufacturers 

of the vehicles covered by this final rule 

would fall under North American 

Industry Classification System (NAICS) 

No. 336211, Automobile Manufacturing, 

which has a size standard of 1,000 

employees or fewer. 

NHTSA estimates that there are three 

small light vehicle manufacturers in the 

U.S. As noted in Section 11.1 of the 

docketed final regulatory impact 

analysis, the estimated annual vehicle 

sales for these three manufacturers 

range from 25 to 100 vehicles with a 

sales price range $24,000 to $750,000 

and estimated annual revenue between 

$2 million and $4 million. We estimate 

that there are several hundred secondstage or final-stage manufacturers and 

alterers that could be impacted by this 

final rule. The agency has analyzed the 

economic impact on these entities. For 

the reasons discussed below and 

detailed in the final regulatory impact 

analysis, we conclude that this rule 

would not have a significant economic 

impact on a substantial number of small 

entities. 

The rule would directly affect motor 

vehicle manufacturers, including small 

light vehicle manufacturers. However, 

we believe that the rule will not have a 

significant economic impact on these 

entities. Small manufacturers are 

already certifying their vehicle’s 

compliance, for the driver position, with 

FMVSS No. 208’s seat belt warning 

system requirements. The means they 

use to certify to the current 

requirements would be similar to or the 

same as those they would use to certify 

to the rear seat belt warning 

requirements and front outboard 

passenger seat belt warning 

requirements under the final rule. 

Further, the compliance test is a 

relatively simple test, involving a test 

technician positioning a person or test 

dummy in a seat and checking if the 

requisite signals activate. Checking to 

see if visual and audible warnings 

activate for the driver seat belt warning 


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246For a discussion of NHTSA’s certification 

regulations for final stage manufacturers, see 71 FR 

28168, May 15, 2006, Docket No. NHTSA–2006– 

24664, Response to petitions for reconsideration of 

a final rule implementing regulations pertaining to 

multi-stage vehicles and to altered vehicles. The 

Background section of that document provides 

concepts and terminology relating to the 

certification of multi-stage vehicles. 

system has been a part of FMVSS No. 

208 compliance testing for many years, 

and manufacturers are knowledgeable 

about conducting such tests. 

Small manufacturers have options 

available to certify compliance, none of 

which will result in a significant 

economic impact on these entities. The 

manufacturers can and do obtain seating 

systems from seat suppliers and install 

the seats on the body following the 

instructions of the seat supplier. Seat 

and seat belt suppliers are large entities 

with resources available to assist small 

manufacturers in incorporating the seat 

belt warning systems, if manufacturers 

need technical assistance (which we do 

not think they will need, given the 

simplicity of the systems, particularly 

those rear systems that do not involve 

occupant detection). We do not believe 

that current manufacturing practices 

will have to change significantly 

because of this rule. 

In addition, we also believe that the 

rule will not have a significant impact 

on small and limited-line vehicle 

manufacturers because the market for 

the vehicles produced by these entities 

is highly inelastic. Purchasers of these 

vehicles are attracted by the desire to 

have an unusual vehicle. Further, all 

light vehicles would have to comply 

with the requirements. Since the price 

of complying with the rule will likely be 

passed on to the final consumer, the 

price of competitor’s models would 

increase by similar amounts. Further, 

we do not believe that raising the price 

of a vehicle to account for the 

incremental costs estimated for this 

final rule ($2.13 for the front outboard 

passenger seat and $19.59 for the rear 

seats) would have much, if any, effect 

on vehicle sales. 

There are a significant number 

(several hundred) of second-stage or 

final-stage manufacturers and alterers 

that would be impacted by a final rule. 

These manufacturers buy incomplete 

vehicles to finish as complete vehicles 

or modify previously certified vehicles. 

Many of these latter vehicles are van 

conversions; there are a variety of 

vehicles affected. 

To produce a vehicle, a final-stage 

manufacturer can either stay within the 

incomplete vehicle document (IVD) 

furnished by the incomplete vehicle 

manufacturer (which are typically large 

vehicle manufacturers, such as GM or 

Ford), or the final-stage manufacturer 

can work with incomplete vehicle 

manufacturers to enable the final-stage 

manufacturer to certify to the new 

requirements.246 The final-stage 

manufacturer can also certify to the 

standard using due care based on an 

assessment of the information available 

to the manufacturer. 

While there are a substantial number 

of multi-stage manufacturers that could 

be impacted by the final rule, we believe 

that the impact on them would not be 

significant. We note that these 

manufacturers are already certifying 

their vehicles to FMVSS No. 208’s seat 

belt warning system requirements that 

apply to the driver seating position. 

They are already familiar with the 

equipment and manufacturing processes 

involved to certify their vehicles to seat 

belt warning system requirements. 

Further, we anticipate that final-stage 

manufacturers will base their vehicles 

on incomplete vehicles that already 

have the seat belt reminder system 

installed rather than install the systems 

themselves. 

For final-stage manufacturers working 

with incomplete vehicles that do not 

have rear seats or seat belt reminder 

systems already installed, we believe 

that completing vehicles to meet the 

requirements would be practicable. The 

manufacturers can obtain seats and seat 

belt systems (with seat belt warning 

system) from suppliers. NHTSA 

recognizes that the suppliers might be 

supplying larger vehicle manufacturers 

during the development and lead time 

period, and do not have the capabilities 

to handle all of the smaller 

manufacturers, including final-stage 

manufacturers. The rulemaking 

accounts for this limitation by allowing 

final-stage manufacturers an additional 

year to comply with the requirements, 

to provide flexibility to these small 

entities and reduce the economic impact 

of the rule on them. (See also 49 CFR 

571.8(b).) 

For an alterer (a person who alters by 

addition, substitution or removal of 

components, other than readily 

attachable components, a certified 

vehicle before the first purchase of the 

vehicle other than for resale), the 

impacts of the rule will not be 

significant. The final rule allows alterers 

an additional year to comply with the 

requirements. For example, if an alterer 

is removing rear seats, the person 

making the alteration would simply 

have to be careful not to render noncompliant the seat belt warning system 

for the remaining seats. (See 49 CFR 

571.8(b).) 

An alterer that is adding rear seats 

could obtain seating systems with seat 

belt warning systems from seat 

suppliers and install the seats on the 

body following the instructions of the 

seat supplier. Changes may have to be 

made to the instrument panel area to 

add the requisite visual signal, but the 

final rule provides flexibility to 

manufacturers in providing the visual 

signal. 

Executive Order 13132 (Federalism) 

NHTSA has examined this rule 

pursuant to Executive Order 13132 (64 

FR 43255; Aug. 10, 1999) and concluded 

that no additional consultation with 

States, local governments, or their 

representatives is mandated beyond the 

rulemaking process. The agency has 

concluded that the rule does not have 

sufficient federalism implications to 

warrant consultation with State and 

local officials or the preparation of a 

federalism summary impact statement. 

The rule does not have ‘‘substantial 

direct effects on the States, on the 

relationship between the national 

government and the States, or on the 

distribution of power and 

responsibilities among the various 

levels of government.’’ 

NHTSA rules can have preemptive 

effect in two ways. First, the National 

Traffic and Motor Vehicle Safety Act 

contains an express preemption 

provision: When a motor vehicle safety 

standard is in effect under this chapter, 

a State or a political subdivision of a 

State may prescribe or continue in effect 

a standard applicable to the same aspect 

of performance of a motor vehicle or 

motor vehicle equipment only if the 

standard is identical to the standard 

prescribed under this chapter. 49 U.S.C. 

30103(b)(1). It is this statutory command 

by Congress that preempts any nonidentical State legislative and 

administrative law address the same 

aspect of performance. 

The express preemption provision 

described above is subject to a savings 

clause under which ‘‘[c]compliance 

with a motor vehicle safety standard 

prescribed under this chapter does not 

exempt a person from liability at 

common law.’’ 49 U.S.C. 30103(e). 

Pursuant to this provision, State 

common law tort causes of action 

against motor vehicle manufacturers 

that might otherwise be preempted by 

the express preemption provision are 

generally preserved. 

NHTSA rules can also preempt State 

law is if complying with the FMVSS 

would render the motor vehicle 

manufacturers liable under State tort 

law. Because most NHTSA standards 

established by an FMVSS are minimum 


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247https://www.reginfo.gov/public/do/ 

PRAViewICR?ref_nbr=202308-2127-002#. 

standards, a State common law tort 

cause of action that seeks to impose a 

higher standard on motor vehicle 

manufacturers will generally not be 

preempted. However, if and when such 

a conflict does exist—for example, when 

the standard at issue is both a minimum 

and a maximum standard—the State 

common law tort cause of action is 

impliedly preempted. See Geier v. 

American Honda Motor Co., 529 U.S. 

861 (2000). 

Pursuant to Executive Order 13132, 

NHTSA has considered whether this 

rule could or should preempt State 

common law causes of action. The 

agency’s ability to announce its 

conclusion regarding the preemptive 

effect of one of its rules reduces the 

likelihood that preemption will be an 

issue in any subsequent tort litigation. 

To this end, the agency has examined 

the nature (e.g., the language and 

structure of the regulatory text) and 

objectives of this rule and finds that this 

rule, like many NHTSA rules, would 

prescribe only a minimum safety 

standard. NHTSA does not intend that 

this rule preempt state tort law that 

would effectively impose a higher 

standard on motor vehicle 

manufacturers than that established by 

this rule. Establishment of a higher 

standard by means of State tort law 

would not conflict with the standards in 

this final rule. Without any conflict, 

there could not be any implied 

preemption of a State common law tort 

cause of action. 

National Environmental Policy Act 

NHTSA has analyzed this rule for the 

purposes of the National Environmental 

Policy Act. In accordance with 49 CFR 

1.81, 42 U.S.C. 4336, and DOT NEPA 

Order 5610.1C, NHTSA has determined 

that this rule is categorically excluded 

pursuant to 23 CFR 771.118(c)(4) 

(planning and administrative activities, 

such as promulgation of rules, that do 

not involve or lead directly to 

construction). This rulemaking, which 

amends Federal Motor Vehicle Safety 

Standard (FMVSS) No. 208, ‘‘Occupant 

crash protection,’’ to require a seat belt 

use warning system for rear seats, 

updates and enhances the current seat 

belt warning requirements for the 

driver’s seat belt, and extends these 

requirements to the front outboard 

passenger seat, is not anticipated to 

result in any environmental impacts, 

and there are no extraordinary 

circumstances present in connection 

with this rulemaking. 

Executive Order 12988 (Civil Justice 

Reform) 

With respect to the review of the 

promulgation of a new regulation, 

section 3(b) of Executive Order 12988, 

‘‘Civil Justice Reform’’ (61 FR 4729, 

February 7, 1996) requires that 

Executive agencies make every 

reasonable effort to ensure that the 

regulation: (1) Clearly specifies the 

preemptive effect; (2) clearly specifies 

the effect on existing Federal law or 

regulation; (3) provides a clear legal 

standard for affected conduct, while 

promoting simplification and burden 

reduction; (4) clearly specifies the 

retroactive effect, if any; (5) adequately 

defines key terms; and (6) addresses 

other important issues affecting clarity 

and general draftsmanship under any 

guidelines issued by the Attorney 

General. This document is consistent 

with that requirement. 

Pursuant to Executive Order 12988, 

NHTSA notes as follows. The issue of 

preemption is discussed above in 

connection with Executive Order 13132. 

NHTSA notes further that there is no 

requirement that individuals submit a 

petition for reconsideration or pursue 

other administrative proceeding before 

they may file suit in court. 

Paperwork Reduction Act 

Under the procedures established by 

the Paperwork Reduction Act of 1995 

(PRA) (44 U.S.C. 3501, et seq.), a Federal 

agency must request and receive 

approval from the Office of Management 

and Budget (OMB) before it collects 

certain information from the public and 

a person is not required to respond to 

a collection of information by a Federal 

agency unless the collection displays a 

valid OMB control number. In 

compliance with these requirements, 

NHTSA is submitting an information 

collection request (ICR) to OMB for 

approval for modifications to a currently 

approved information collection titled 

‘‘Consolidated Vehicle Owner’s Manual 

Requirements for Motor Vehicles and 

Motor Vehicle Equipment’’ (OMB 

Control No. 2127–0541, Current 

Expiration Date: 03/31/2026). 

This final rule amends 49 CFR 

571.208 to, among other things, add new 

owner’s manual requirements. NHTSA 

submitted an ICR to OMB for review 

when the NPRM was published.247

OMB deferred review until after 

receiving NHTSA’s summary and 

response to all comments related to the 

information collection requirements 

contained in this rulemaking. 

Accordingly, NHTSA is resubmitting 

the ICR for this final rule. 

NHTSA’s ICR describes the nature of 

the information collections and their 

expected burden. The ICR is for fifteen 

mandatory and voluntary disclosure 

requirements for manufacturers of motor 

vehicles and items of motor vehicle 

equipment. Pursuant to 49 U.S.C. 30117, 

the Secretary (NHTSA by delegation) is 

authorized to require manufacturers to 

provide information to first purchasers 

of motor vehicles or items of motor 

vehicle equipment related to 

performance and safety in printed 

materials that are attached to or 

accompany the motor vehicle or item of 

motor vehicle equipment. NHTSA has 

exercised this authority to require 

manufacturers to provide certain 

specified safety information to be 

readily available to consumers and 

purchasers of motor vehicles and items 

of motor vehicle equipment. This 

information is most often provided in 

vehicle owners’ manuals and the 

requirements are found in 49 CFR parts 

563, 571, and 575. Some of these 

requirements are contained in the 

Federal Motor Vehicle Safety Standards 

(FMVSS) that set performance 

requirements for motor vehicles and 

items of motor vehicle equipment. The 

other requirements are contained in 

separate regulations. Manufacturers 

must comply with these requirements 

whenever they manufacture a vehicle or 

equipment item that is subject to the 

requirements. The purpose of the 

required disclosures is to provide 

important safety information to vehicle 

owners. 

This final rule makes changes to 

existing an information collection 

requiring that the owner’s manual 

describe the vehicle’s seat belt warning 

system features, including the location, 

format, and meaning of the visual 

warnings. It also requires that the 

owner’s manual include instructions on 

how to make any manual electrical 

connections for readily removable seats. 

These changes are finalized without any 

substantive changes from those 

proposed in the NPRM. 

We received comments on the 

proposed changes. ASC supported the 

proposed changes to the owner’s 

manual requirements. NSC suggested 

standardizing generic nomenclature and 

warning and icon symbols to reduce 

driver confusion. Regarding installation 

of child restraint systems, Auto 

Innovators emphasized that additional 

information about system design can be 

included at the discretion of the 

manufacturer, and SRN suggested that 

instructions regarding how to interpret 

certain warnings should be included in 


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the child passenger section of the 

manual. These comments are discussed 

in Section VI.A.2.d. 

As described in the NPRM, NHTSA 

estimates that the total burden of the 

ICR is approximately 10,172 hours and 

$8,726,501 annually. This burden 

represents an increase in estimated 

burden hours of 1,544 hours (8,628 

hours to 10,172 hours) and an increase 

in costs of $755,040 ($7,971,461 to 

$8,726,501), compared with existing 

requirements. The change in burden 

reflects changes as a result of the 

rulemaking requiring the development 

and publication of new information for 

the owner’s manual. Printing costs have 

increased due to accounting for the 

estimated number of vehicles that will 

be equipped with seat belt reminder 

systems and will therefore need to 

comply with the requirements to 

provide system information and 

operating instructions. We did not 

receive comments on these burden 

estimates or other aspects of the 

proposed revision to the information 

collection. These burden estimates did 

not change between the NPRM and final 

rule. 

National Technology Transfer and 

Advancement Act 

Under the National Technology 

Transfer and Advancement Act of 1995 

(NTTAA) (Pub. L. 104–113), ‘‘all Federal 

agencies and departments shall use 

technical standards that are developed 

or adopted by voluntary consensus 

standards bodies, using such technical 

standards as a means to carry out policy 

objectives or activities determined by 

the agencies and departments.’’ 

Voluntary consensus standards are 

technical standards (e.g., materials 

specifications, test methods, sampling 

procedures, and business practices) that 

are developed or adopted by voluntary 

consensus standards bodies, such as 

SAE (formerly, the Society of 

Automotive Engineers). The NTTAA 

directs this agency to provide Congress, 

through OMB, explanations when the 

agency decides not to use available and 

applicable voluntary consensus 

standards. 

While the agency is not aware of any 

voluntary standards that exist regarding 

the seat belt warnings contemplated in 

this rule, the agency has examined 

relevant regulations in other countries, 

such as the European Union standard 

ECE R16. As discussed above, although 

we are not aware of any foreign 

regulations that require seat belt 

warnings for the front outboard 

passenger or rear seat belts or for the 

driver seat on small buses, we believe 

that requiring seat belt warnings for 

these seating positions and for the 

driver seats on small buses meets a 

safety need and is practicable. 

Severability 

The issue of severability of FMVSS is 

addressed in 49 CFR 571.9. It provides 

that if any FMVSS or its application to 

any person or circumstance is held 

invalid, the remainder of the part and 

the application of that standard to other 

persons or circumstances is unaffected. 

Unfunded Mandates Reform Act 

The Unfunded Mandates Reform Act 

of 1995 (Pub. L. 104–4) (UMRA) 

requires agencies to prepare a written 

assessment of the costs, benefits, and 

other effects of proposed or final rules 

that include a Federal mandate likely to 

result in the expenditures by States, 

local or tribal governments, in the 

aggregate, or by the private sector, of 

$100 million or more (adjusted annually 

for inflation with base year of 1995) in 

any one year. Adjusting this amount by 

the implicit gross domestic product 

price deflator for 2022 results in $177 

million (111.416/75.324 = 1.48). The 

assessment may be included in 

conjunction with other assessments, as 

it is here. 

UMRA requires the agency to select 

the ‘‘least costly, most cost-effective or 

least burdensome alternative that 

achieves the objectives of the rule.’’ As 

discussed above, the agency considered 

alternatives to the final rule and has 

concluded that the requirements are the 

most cost-effective alternatives that 

achieve the objectives of the rule. 

This rule on seat belt reminder 

systems is not likely to result in 

expenditures by State, local or tribal 

governments of more than $177 million 

annually. However, it is estimated to 

result in the expenditure by automobile 

manufacturers and/or their suppliers by 

approximately $168 million annually. 

The estimated costs are discussed in 

Section VIII, Overview of Benefits and 

Costs, and the docketed final regulatory 

impact analysis. 

We have concluded that the 

requirements in this rule are the most 

cost-effective alternatives that achieve 

the objectives of the rule. 

Plain Language 

Executive Order 12866 and E.O. 

13563 require each agency to write all 

rules in plain language. Application of 

the principles of plain language 

includes consideration of the following 

questions: 

• Have we organized the material to 

suit the public’s needs? 

• Are the requirements in the rule 

clearly stated? 

• Does the rule contain technical 

language or jargon that isn’t clear? 

• Would a different format (grouping 

and order of sections, use of headings, 

paragraphing) make the rule easier to 

understand? 

• Would more (but shorter) sections 

be better? 

• Could we improve clarity by adding 

tables, lists, or diagrams? 

• What else could we do to make the 

rule easier to understand? 

NHTSA has considered these 

questions and attempted to use plain 

language in writing this rule. Please 

inform the agency if you can suggest 

how NHTSA can improve its use of 

plain language. 

Regulation Identifier Number (RIN) 

The Department of Transportation 

assigns a regulation identifier number 

(RIN) to each regulatory action listed in 

the Unified Agenda of Federal 

Regulations. The Regulatory Information 

Service Center publishes the Unified 

Agenda in April and October of each 

year. You may use the RIN contained in 

the heading at the beginning of this 

document to find this action in the 

Unified Agenda. 

Note: The following appendix will not 

appear in the Code of Federal Regulations. 

Appendix A. List of Comments Cited in 

Preamble 

Commenter Comment ID 

Advocates for Highway and Auto Safety and Public Citizen (Advocates and Public Citizen) .................................. NHTSA–2023–0032–0040 

Alliance for Automotive Innovation (Auto Innovators) ............................................................................................... NHTSA–2023–0032–0048 

Automotive Safety Council (ASC) .............................................................................................................................. NHTSA–2023–0032–0015 

Autonomous Vehicle Industry Association (AVIA) ..................................................................................................... NHTSA–2023–0032–0029 

Braun Northwest, Inc. (BNW) .................................................................................................................................... NHTSA–2023–0032–0050 

Consumer Reports ..................................................................................................................................................... NHTSA–2023–0032–0049 

Cross, Karleigh ........................................................................................................................................................... NHTSA–2023–0032–0013 

Dorey, Rivers ............................................................................................................................................................. NHTSA–2023–0032–0008 


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Federal Register / Vol. 90, No. 2 / Friday, January 3, 2025 / Rules and Regulations 459 

Commenter Comment ID 

Ford Motor Company (Ford) ...................................................................................................................................... NHTSA–2023–0032–0045 

Freedman Seating Company (Freedman) ................................................................................................................. NHTSA–2023–0032–0041 

Freeman, Paige .......................................................................................................................................................... NHTSA–2023–0032–0017 

Gaal, Edward ............................................................................................................................................................. NHTSA–2023–0032–0010 

General Motors (GM) ................................................................................................................................................. NHTSA–2023–0032–0026 

American Honda Motor Co. (Honda) ......................................................................................................................... NHTSA–2023–0032–0039 

Hyundai America Technical Center, Inc. (HATCI) ..................................................................................................... NHTSA–2023–0032–0053 

Hyundai Motor Company (Hyundai) .......................................................................................................................... NHTSA–2023–0032–0047 

IEE .............................................................................................................................................................................. NHTSA–2023–0032–0032 

Insurance Institute for Highway Safety (IIHS) ........................................................................................................... NHTSA–2023–0032–0020 

InterMotive Vehicle Controls (InterMotive) ................................................................................................................. NHTSA–2023–0032–0016 

Koo, John ................................................................................................................................................................... NHTSA–2023–0032–0012 

Mothers Against Drunk Driving (MADD) .................................................................................................................... NHTSA–2023–0032–0055 

Mercedes-Benz and Mercedes-Benz Research and Development North America (Mercedes) ............................... NHTSA–2023–0032–0025 

National Association of Mutual Insurance Companies (NAMIC) ............................................................................... NHTSA–2023–0032–0034 

National Automobile Dealers Association (NADA) .................................................................................................... NHTSA–2023–0032–0042 

National Safety Council (NSC) .................................................................................................................................. NHTSA–2023–0032–0038 

Nissan North America ................................................................................................................................................ NHTSA–2023–0032–0043 

National Transportation Safety Board (NTSB) .......................................................................................................... NHTSA–2023–0032–0019 

Paradise, John ........................................................................................................................................................... NHTSA–2023–0032–0009 

Recreational Vehicle Industry Association (RVIA) ..................................................................................................... NHTSA–2023–0032–0028 

Rivian Automotive ...................................................................................................................................................... NHTSA–2023–0032–0044 

Safe Kids Worldwide (SKW) ...................................................................................................................................... NHTSA–2023–0032–0046 

Safe Ride News (SRN) .............................................................................................................................................. NHTSA–2023–0032–0036 

Stange, Trenton ......................................................................................................................................................... NHTSA–2023–0032–0018 

Tesla ........................................................................................................................................................................... NHTSA–2023–0032–0035 

Tombrello, Stephanie ................................................................................................................................................. NHTSA–2023–0032–0030 

Toyota Motor North America, Inc. and Toyota Motor Corporation (Toyota) ............................................................. NHTSA–2023–0032–0054 

Anonymous #5 ........................................................................................................................................................... NHTSA–2023–0032–0005 

Anonymous #24 ......................................................................................................................................................... NHTSA–2023–0032–0024 

Anonymous #33 ......................................................................................................................................................... NHTSA–2023–0032–0033 

List of Subjects in 49 CFR Part 571 

Imports, Motor vehicle safety, Motor 

vehicles. 

In consideration of the foregoing, 

NHTSA amends 49 CFR part 571 as set 

forth below. 

PART 571—FEDERAL MOTOR 

VEHICLE SAFETY STANDARDS 

■ 1. The authority citation for part 571 

of title 49 continues to read as follows: 

Authority: 49 U.S.C. 322, 30111, 30115, 

30117, and 30166; delegation of authority at 

49 CFR 1.95. 

■ 2. Amend § 571.101 by revising 

paragraph S5.5.6 and tables 1 and 2 to 

read as follows. 

§ 571.101 Standard No. 101; Controls and 

displays. 

* * * * * 

S5.5.6(a) Except as provided in 

S5.5.6(b) and (c), messages displayed in 

a common space may be cancelable 

automatically or by the driver. 

(b) Telltales for high beams, turn 

signal, low tire pressure, and passenger 

air bag off, and telltales for which the 

color red is required in table 1 to this 

section must not be cancelable while the 

underlying condition for their activation 

exists. 

(c) Telltales for the seat belts must not 

be cancelable by the driver before the 

minimum durations are satisfied but 

may be cancellable automatically as 

specified in FMVSS No. 208 (§ 571.208). 

* * * * * 

BILLING CODE 4910–59–P 


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460 Federal Register / Vol. 90, No. 2 / Friday, January 3, 2025 / Rules and Regulations 

Table 1 to § 571.101 


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Controls, Telltales, and Indicators 

With Illumination or Color Requirements1 

Column 1 Column 2 Column 3 Column 4 

ITEM SYMBOL WORDSOR FUNCTION 

ABBREVIATIONS 

Highbeam 2 ~D ------- Telltale 

3, 5 

Tum signals 2 

¢11;~ Control 

-------

3, 6 Telltale 

Hazard warning signal A Hazard Control 

3 ------- Telltale 7 

Position, side marker, end-

;oo-=- Marker Lamps outline marker, identification, or Control or clearance lamps .,,. ... 3,8 MKLps 8 

Windshield wiping system \9 Wiper 

or Control 

Wipe 

Windshield washing system {p Washer 

or Control 

Wash 

Windshield washing and wiping 

~ Washer-Wiper system combined or Control 

Wash-Wipe 

Windshield defrosting and 

~ Defrost, Defog, defogging system or Control 

Def. 

Rear window defrosting and [il Rear Defrost, 

defogging system Rear Defog, Control Rear Def., or 

R-Def. 

Brake system malfunction 

------- Brake Telltale 

Antilock brake system Antilock, 

malfunction for vehicles subject ------- Anti-lock, or Telltale 

to FMVSS 105 or 135 ABS 9 

Column 5 Column 6 

TLLUMTN- COLOR 

ATION 

Blue or ------- Green 4 

------- -------

------- Green 4 

Yes -------

------- -------

Yes -------

Yes -------

Yes -------

Yes -------

Yes -------

Yes -------

------- Red 4 

------- Yellow 
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Column 1 Column 2 Column3 Column 4 Column 5 Column 6 

ITEM SYMBOL WORDS OR FUNCTION ILLUMIN- COLOR 

ABBRE- ATION 

VIATIONS 

Malfunction in Variable Brake Brake Proportioning System ------- Proportioning 9 Telltale ------- Yellow 

Regenerative brake system RBS or malfunction ------- ABS/RBS Telltale ------- Yellow 9 

Malfunction in antilock system ABS 

for vehicles other than trailers ------- or Telltale ------- Yellow 

subject to FMVSS 121 Antilock 9 

Antilock brake system trailer ta. Trailer ABS 

fault for vehicles subject to or Telltale ------- Yellow 

FMVSS 121 00 Trailer Antilock 

Brake pressure 

(for vehicles subject to FMVSS ------- Brake Pressure 9 Telltale ------- Red 4 

105 or 135) 

Low brake fluid condition 

(for vehicles subject to FMVSS ------- Brake Fluid 9 Telltale ------- Red 4 

105 or 135) 

Parking brake applied Park or (for vehicles subject to FMVSS ------- Parking Brake Telltale ------- Red 4 

105 or 135) 9 

Brake lining wear-out condition 

(for vehicles subject to FMVSS ------- Brake Wear 9 Telltale ------- Red 4 

135) 

Electronic Stability Control 1j System Malfunction 

ESC Telltale Yellow (for vehicles subject to FMVSS 12 -------

126) lO, 11 

Electronic Stability Control JS Control Yes ------- System "OFF" 

(for vehicles subject to FMVSS ESC OFF 

126) 10 OFF Telltale ------- Yellow 
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Column 1 Column2 Column3 Column 4 Column 5 Column 6 

ITEM SYMBOL WORDS OR FUNCTION ILLUMIN- COLOR 

ABBRE- ATION 

VIATIONS 

Electronic Stability Control IS System Malfunction 

(for vehicles subject to FMVSS 

136) 11 or 

I 

~~ ESC Telltale ------- Yellow 

or 

ii 

~~ 

Fuel Level ~ Telltale ------- -------

or Fuel 

fl) Indicator Yes -------

Engine oil pressure Telltale ------- -------

~ Oil 

13 Indicator Yes -------

Engine coolant temperature 

-~-

Telltale ------- -------

Temp 

- 13 Indicator Yes -------

Electrical charge E3 Volts or Telltale ------- -------

Charge or 

Amp Indicator Yes -------

Engine stop 

------- Engine Stop 14 Control Yes -------

Automatic vehicle speed 

( cruise control) ------- ------- Control Yes -------

Speedometer MPH,orMPH ------- Indicator Yes ------- and km/h 15 

Heating and Air conditioning 

system ------- ------- Control Yes -------
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Column 1 Column 2 Column 3 Column 4 Column 5 Column 6 

ITEM SYMBOL WORDS OR FUNCTION ILLUMIN- COLOR 

ABBRE- ATION 

VIATIONS 

Automatic (park) p 

transmission (reverse) R 

control (neutral) ------- N Indicator Yes ------- position ( drive) D 16 

Heating and/or air conditioning • fan 

or Fan Control Yes -------

8B 

Low Tire Pressure (l) (including malfunction) Low Tire 17 Telltale ------- Yellow 

(See FMVSS 138) 17 

Low Tire Pressure 

6" (including malfunction that 

Low Tire Telltale Yellow identifies involved tire) 17 -------

(See FMVSS 138) 

Tire Pressure Monitoring 

System Malfunction ------- TPMS 17, 19 Telltale ------- Yellow 

(See FMVSS 138) 18 

Rear Seat Belt Waming20 ------- ------- Telltale ------- Green or 

Red21 

Notes to table I to § 571.101: 

1An identifier is shown in this table ifit is required for a control for which an illumination requirement exists or ifit is used for a telltale for which 

a color requirement exists. If a line appears in column 2 and column 3, the control, telltale, or indicator is required to be identified, however the 

form of the identification is the manufacturer's option. Telltales are not considered to have an illumination requirement, because by definition the 

telltale must light when the condition for its activation exists. 

2 Additional requirements in FMVSS 108. 

3 Framed areas of the symbol may be solid; solid areas may be framed. 

4 Blue may be blue-green. Red may be red-orange. 

5 Symbols employing four lines instead of five may also be used. 

6 The pair of arrows is a single symbol. When the controls or telltales for left and right tum operate independently, however, the two arrows may 

be considered separate symbols and be spaced accordingly. 

7 Not required when arrows of tum signal telltales that otherwise operate independently flash simultaneously as hazard warning telltale. 

8 Separate identification is not required if function is combined with master lighting switch. 
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9 Refer to FMVSS 105 or FMVSS 135, as appropriate, for additional specific requirements for brake telltale labeling and color. Ifa single telltale 

is used to indicate more than one brake system condition, the brake system malfunction identifier must be used. 

10 Requirement effective September 1, 2011. 

11 A manufacturer may use this telltale in flashing mode to indicate ESC operation. 

12 This symbol may also be used to indicate the malfunction ofrelated systems/functions, including traction control, trailer stability assist, comer 

brake control, and other similar functions that use throttle and/or individual wheel torque control to operate and share common components with 

ESC. 

13 Combination of the engine oil pressure symbol and the engine coolant temperature symbol in a single telltale is permitted. 

14 Use when engine control is separate from the key locking system. 

15 If the speedometer is graduated in both miles per hour and in kilometers per hour, the scales must be identified "MPH" and "km/h", 

respectively, in any combination of upper- and lowercase letters. 

16 The letters 'P', 'R', 'N', and 'D' are considered separate identifiers for the individual gear positions. Their locations within the vehicle, and with 

respect to each other, are governed by FMVSS 102. The letter 'D' may be replaced by another alphanumeric character or symbol chosen by the 

manufacturer. 

17 Required only for FMVSS 138 compliant vehicles. 

18 Alternatively, either low tire pressure telltale may be used to indicate a TPMS malfunction. See FMVSS 138. 

19 Required only for vehicles manufactured on or after September I, 2007. 

20 Refer to FMVSS 208 for additional requirements. 

21 These are the colors if symbols or numbers are chosen. If a symbol or number is used to indicate to the driver how many or which rear seat 

belts are in use, the color of the illuminated symbol or number must be green. If a symbol or number is used to indicate to the driver how many 

or which rear seat belts are not in use, or how many or which rear seat belts have undergone a change of status from in use to not in use, the color 

of the illuminated symbol or number must be red. See FMVSS 208 S7.5(c)(3). 
Federal Register / Vol. 90, No. 2 / Friday, January 3, 2025 / Rules and Regulations 465 

Table 2 to § 571.101 

BILLING CODE 4910–59–C 

■ 3. Amend § 571.208 by: 

■ a. Adding paragraphs S4.1.5.7, 

S4.1.5.7.1, S4.1.5.8, S4.1.5.8.1, S4.2.8, 

S4.2.8.1, S4.2.9, S4.2.9.1, S4.4.3.4, 

S4.4.3.4.1, S4.4.3.5, S4.4.3.5.1, and 

S4.5.1.(f)(3); 

■ b. Revising paragraph S4.5.3.3(b); and 

■ c. Adding paragraph S7.5. 

The additions and revisions read as 

follows: 

§ 571.208 Standard No. 208; Occupant 

crash protection. 

* * * * * 

S4.1.5.7. Front seat belt warnings for 

passenger cars manufactured on or after 

September 1, 2026. 

S4.1.5.7.1 Any front outboard 

designated seating position and any 

inboard designated seating position for 

which a seat belt warning is required in 

S4.1.5.6 shall comply with S7.5 of this 

standard. 

S4.1.5.8. Rear seat belt warnings for 

passenger cars manufactured on or after 

September 1, 2027. 

S4.1.5.8.1. All rear designated seating 

positions, except in law enforcement 

vehicles, shall comply with S7.5 of this 

standard. 

* * * * * 

S4.2.8 Front seat belt warnings for 

trucks and multipurpose passenger 

vehicles manufactured on or after 

September 1, 2026 with a GVWR of 

4,536 kg (10,000 lb) or less. 

S4.2.8.1. Any front outboard 

designated seating position certified to a 

compliance option requiring a seat belt 

and any inboard designated seating 

position for which a seat belt warning 

is required by S4.2.6.4 shall comply 

with S7.5 of this standard. 


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Identifiers for 

Controls, Telltales, and Indicators with 

No Color or Illumination Requirements 

Column 2 SYMBOL Column 3 WORD(S) OR 

Column I ITEM ABBREVIATION 

!Hand Throttle Control Throttle 

[Engine Start Control Engine Start1 

!Manual Choke Control Choke 

Kilometers or km, 

Odometer if kilometers are shown. Otherwise, no 

identifier is required.2 

!Horn ~ Hom 

!Master Lighting Switch 

-nLights 

' I '3 

!Headlamps and Taillamps Control - - 4,5 

!Low Brake Air Pressure Telltale (for 

~ehicles subject to FMVSS 121) Brake Air 

!Front Seat Belt Unfastened Telltale Fasten Belts or Fasten Seat Belts 

·-'~ 

Notes to table 2 to § 571.101: 1. Use when engine control is separate from the key locking system. 

2. Any combination of upper- or lowercase letters may be used. 

3. Framed areas may be filled. 

4. If a line appears in Column 2 and Column 3, the Control, Telltale or Indicator is required to be identified, however the 

form of the identification is the manufacturer's option. 

5. Separate identification not required if function is combined with Master Lighting Switch. 
466 Federal Register / Vol. 90, No. 2 / Friday, January 3, 2025 / Rules and Regulations 

S4.2.9 Rear seat belt warnings for 

trucks and multipurpose passenger 

vehicles manufactured on or after 

September 1, 2027 with a GVWR of 

4,536 kg (10,000 lb) or less. 

S4.2.9.1. All rear designated seating 

positions certified to a compliance 

option requiring a seat belt, except 

ambulances, as defined by FMVSS No. 

201 (§ 571.201), and law enforcement 

vehicles, shall comply with S7.5 of this 

standard. 

* * * * * 

S4.4.3.4 Front seat belt warnings for 

buses manufactured on or after 

September 1, 2026 with a GVWR of 

4,536 kg (10,000 lb) or less. 

S4.4.3.4.1 All front outboard 

designated seating positions and any 

inboard designated seating position for 

which a seat belt warning is required by 

S4.2.6.4 shall comply with S7.5 of this 

standard. 

S4.4.3.5 Rear seat belt warnings for 

buses manufactured on or after 

September 1, 2027 with a GVWR of 

4,536 kg (10,000 lb) or less. 

S4.4.3.5.1 All rear designated 

seating positions certified to a 

compliance option requiring a seat belt, 

except for school buses and law 

enforcement vehicles, shall comply with 

S7.5 of this standard. 

* * * * * 

S4.5.1 * * * 

(f) * * * 

(3) The owner’s manual (which 

includes information provided by the 

vehicle manufacturer to the consumer, 

whether in digital or printed form) for 

any vehicle equipped with a seat belt 

warning system must include an 

accurate description of the system 

features and warning signals, including 

the location and format of the visual 

warnings, in an easily understandable 

format. The description shall include 

information on when the different 

features of the warning system will 

activate and how to interpret the visual 

warnings. For vehicles with any rear 

designated seating position that is a 

readily-removable seat (a seat designed 

to be easily removed and replaced by 

means installed by the manufacturer for 

that purpose) equipped with manual 

electrical connections that are utilized 

by the rear seat belt warning system, the 

owner’s manual must include a 

description of the purpose of the 

connection, instructions on how to 

achieve a proper connection, and a 

description of how not achieving a 

proper connection may affect the proper 

functioning of the system. 

* * * * * 

S4.5.3.3 * * * 

(b) Conform to the seat belt warning 

system requirements of S7.3 or S7.5 of 

this standard, as applicable. 

* * * * * 

S7.5 Seat belt warning systems for 

front outboard seat belt assemblies in 

vehicles manufactured on or after 

September 1, 2026 provided in 

accordance with the requirements of 

S4.1.5.7, S4.2.8, S4.4.3.4, and S4.5.3.3 

of this standard, and rear seat belt 

assemblies in vehicles manufactured on 

or after September 1, 2027 provided in 

accordance with the requirements of 

S4.1.5.8, S4.2.9, S4.4.3.5, and S4.5.3.3 

of this standard. 

(a) Definitions for S7.5. (1) A manual 

seat belt is not in use when the seat belt 

latch mechanism is not fastened. A seat 

belt is in use when the seat belt latch 

mechanism is fastened. An automatic 

seat belt is not in use when the seat belt 

latch mechanism is not fastened or, if 

the automatic belt is non-detachable, the 

emergency release mechanism is in the 

released position. If the automatic seat 

belt is motorized, whether the seat belt 

is in use is determined when the seat 

belt webbing is in its locked protective 

mode at the anchorage point. 

(2) A warning cycle for an intermittent 

audible warning consists of period(s) 

when the warning is active at the chime 

frequency or continuously, and of 

inactive period(s). A warning cycle 

begins with an active period and is 30 

seconds in duration. 

(3) Chime frequency means the 

repetition rate for an intermittent 

audible warning when the warning is 

active. 

(4) Duty cycle means the total amount 

of time an intermittent audible warning 

is active during a warning cycle at the 

chime frequency or continuously, 

divided by the total warning cycle 

duration (30 seconds). 

(5) A readily-removable seat means a 

seat designed to be easily removed and 

replaced by means installed by the 

manufacturer for that purpose. 

(6) Seat centerline means the line 

formed by the intersection of the seating 

surface and the vertical plane that 

passes through the ‘‘seating reference 

point’’ (as defined at 49 CFR 571.3) and 

is parallel to the direction that the seat 

faces. 

(b) Front seat belt warning system. A 

driver’s designated seating position and 

any front outboard passenger 

designating seating position must be 

equipped with an audio-visual seat belt 

warning meeting the requirements of 

S7.5(b)(1) through (4) when tested in 

accordance with S7.5(d). 

(1) Visual warning. (i) A visual 

warning must activate and remain active 

whenever the ignition switch is in the 

‘‘on’’ or ‘‘start’’ position (or the 

propulsion system is activated), the seat 

is occupied, and the seat belt is not in 

use. 

(ii) Vehicles with a driver’s designated 

seating position. The visual warning for 

the driver’s seat belt and the visual 

warning for the front outboard 

passenger seat belt must be visible from 

the driver’s seat. If the vehicle has a 

mode of driverless operation, the visual 

warning for the front outboard 

passenger seat belt must also be visible 

from the front outboard passenger seat. 

(iii) Vehicles without a driver’s 

designated seating position. The visual 

warning for each outboard passenger 

designated seating position must be 

visible from each outboard passenger 

designated seating position. 

(iv) The visual warning may be 

continuous or intermittent and must 

display the identifying symbol or the 

words specified in table 2 of FMVSS No. 

101 (§ 571.101). 

(v) For a visual warning associated 

with multiple front outboard seats, the 

visual warning must clearly identify the 

seating positions for which the warnings 

are intended. 

(vi) The visual warning must not be 

overridden by other warnings. 

(2) Audible warning—first phase. (i) 

An audible warning must activate when 

the ignition switch is placed in the ‘‘on’’ 

or ‘‘start’’ position (or upon manual 

activation of the propulsion system, but 

prior to the vehicle being placed in 

‘‘possible active driving mode’’ as 

defined by FMVSS No. 305 (§ 571.305)), 

the seat is occupied, and the seat belt is 

not in use. 

(ii) The audible warning must 

continue for 30 seconds, until the seat 

belt that triggered the warning is in use, 

until the seat is no longer occupied, or 

until the second-phase warning 

activates, whichever comes first. The 

audible warning may be paused during 

the activation of another audible safety 

warning that is designed to alert the 

driver to take immediate action, but the 

seat belt audible warning must be 

resumed for the remainder of the 

required duration after the other audible 

warning deactivates. 

(iii) The audible warning may be 

continuous or intermittent. If 

intermittent, inactive periods longer 

than 3 seconds will not be counted 

toward the total duration of the audible 

warning, and there must be no inactive 

periods greater than 10 seconds. The 

same audible warning may be used for 

all front and rear seats. 

(3) Audible warning—second phase. 

(i) The audible warning must activate 

and remain active when the vehicle 


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Federal Register / Vol. 90, No. 2 / Friday, January 3, 2025 / Rules and Regulations 467 

speed is equal to or greater than 10 km/ 

h (6.2 mph), the seat is occupied, and 

the seat belt is not in use. The audible 

warning may be paused during the 

activation of another audible safety 

warning that is designed to alert the 

driver to take immediate action, but the 

seat belt audible warning must be 

resumed after the other audible warning 

deactivates. 

(ii) The audible warning may be 

continuous or intermittent. If 

intermittent, the audible warning when 

active must be continuous or have a 

chime frequency of at least 0.5 Hz and 

a duty cycle of at least 0.2. The same 

audible warning may be used for all 

front and rear seats. 

(4) Cancellation. The warning must 

not be able to be canceled or 

deactivated. 

(c) Rear passenger seat belt warning 

system. All rear designated seating 

positions must be equipped with a 

warning system meeting the 

requirements of S7.5(c)(1) through (7) 

when tested in accordance with S7.5(d). 

(1) Start-of-trip warning. A visual 

warning indicating how many or which 

rear seat belts are in use and/or not in 

use must activate when the ignition 

switch is placed in the ‘‘on’’ or ‘‘start’’ 

position (or upon manual activation of 

the propulsion system, but prior to the 

vehicle being placed in ‘‘possible active 

driving mode’’ as defined by FMVSS 

No. 305 (§ 571.305)) and continue for at 

least 60 seconds. 

(i) No visual warning is required for: 

(A) an unoccupied seat if the system 

is able to determine whether or not a 

seat is occupied; 

(B) a seat belt that is in use in a 

system designed to indicate to the driver 

how many or which rear seat belts are 

not in use; and 

(C) a seat belt that is not in use in a 

system designed to indicate to the driver 

how many or which rear seat belts are 

in use. 

(2) Change-of-status warning. An 

audio-visual warning indicating how 

many or which rear seat belts have 

undergone a change of status from in 

use to not in use must activate when the 

status of any rear seat belt changes from 

in use to not in use and the vehicle is 

in forward or reverse drive mode, unless 

any rear door is open. The warning must 

continue for at least 30 seconds or until 

the seat belt that triggered the warning 

is in use. The warning may deactivate 

if the system is able to determine that 

the number of seat belts in use is 

restored and all the doors remained 

closed. 

(3) Additional visual warning 

requirements. (i) The warning may be 

continuous or intermittent and may 

consist of text, symbols, and/or 

numbers. 

(ii) The warning must be visible from 

the driver’s seat. 

(iii) If the warning is designed to 

indicate how many or which rear seat 

belts are in use, the color of the symbols 

or numbers indicating seat belts in use 

must be green. If the warning is 

designed to indicate to the driver how 

many or which rear seat belts are not in 

use, the color of the symbols or numbers 

indicating seat belts not in use must be 

red. 

(iv) The change-of-status visual 

warning may use the same telltale as the 

start of trip warning, provided that the 

color of an illuminated symbol or 

number used to indicate to the driver 

how many or which rear seat belts have 

undergone a change of status from in 

use to not in use is red. 

(v) The warning must not be 

overridden by other visual warnings for 

the required duration. 

(4) Audible warning requirements. (i) 

The audible warning may be continuous 

or intermittent. If intermittent, inactive 

periods longer than 3 seconds will not 

be counted toward the total duration of 

the warning, and there must be no 

inactive periods greater than 10 

seconds. 

(ii) The audible warning may be 

paused during the activation of another 

audible safety warning that is designed 

to alert the driver to take immediate 

action, but the seat belt audible warning 

must be resumed for the remainder of 

the required duration after the other 

audible warning deactivates. 

(iii) The same audible warning may be 

used for all front and rear seats. 

(5) Cancellation. The warning must 

not be able to be canceled or 

deactivated. 

(6) Seat electrical connection 

requirements. Any rear designated 

seating position consisting of a readilyremovable seat that is equipped with 

electrical connections utilized by the 

rear seat belt warning system must 

either— 

(i) Automatically connect the 

electrical connections when the seat is 

put in place; or 

(ii) If a manual electrical connection 

is required, the connectors must be 

readily accessible. 

(7) Electrical connection warning 

signal. Vehicles that provide a visual 

warning designed to indicate to the 

driver how many or which rear seat 

belts are not in use and are equipped 

with any readily removable rear seats 

must, when the ignition switch is 

placed in the ‘‘on’’ or ‘‘start’’ position 

(or upon manual activation of the 

propulsion system, but prior to the 

vehicle being placed in ‘‘possible active 

driving mode’’ as defined by FMVSS 

No. 305 (§ 571.305)) provide a visual 

warning visible from the driver’s seat if 

a seat has been installed and a proper 

electrical connection has not been 

made. The visual warning may be 

intermittent but must remain active 

until all rear seat electrical connections 

are properly made. 

(d) Test procedures. (1) Occupied 

designated seating positions. If testing 

with a designated seating position 

occupied, the following apply, at the 

option of the manufacturer: 

(i) Front outboard seating positions. 

(A) Seat the 5th percentile female test 

dummy described in part 572, subpart O 

of this chapter, as well as any larger 

dummy described in part 572 of this 

chapter; or 

(B) Seat any human occupant that 

weighs 46.7 kg (103 lb) or more and is 

139.7 cm (55 inches) tall or taller. 

(ii) Driver’s seating position. (A) Seat 

the 5th percentile female test dummy 

described in part 572, subpart O of this 

chapter, as well as any larger dummy 

described in part 572 of this chapter; 

(B) Seat any human occupant that 

weighs 46.7 kg (103 lb) or more and is 

139.7 cm (55 inches) tall or taller; or 

(C) The seat may be considered 

occupied when the ignition switch is in 

the ‘‘on’’ or ‘‘start’’ position (or the 

propulsion system is activated). 

(iii) Rear seating positions. (A) Seat 

the 6-year-old child dummy described 

in part 572, subpart N of this chapter, 

as well as any larger dummy described 

in part 572 of this chapter; or 

(B) Seat any human occupant that 

weighs 21 kg (46.5 lb) or more and is 

114 cm (45 inches) tall or taller. 

(iv) Compliance option selection. The 

manufacturer shall select a compliance 

option by the time it certifies the vehicle 

and may not thereafter select a different 

option for the vehicle. Each 

manufacturer shall provide information 

to NHTSA regarding which of the 

compliance options it has selected for a 

particular vehicle or make/model upon 

request. 

(2) Seating procedures—(i) Seat 

adjustment. If adjustable, the seat back 

shall be placed in the manufacturer’s 

nominal design riding position, with 

any other seat adjustments in any 

position, and any adjustable seat belt 

anchorages in any position. 

(ii) Test dummy. Seat the test dummy 

such that the midsagittal plane of the 

dummy is vertical and within ±10 mm 

of the seat centerline, with the torso and 

pelvis in contact with the seat back. The 

dummy may be clothed in any manner. 

(iii) Human occupant. The occupant 

shall assume, to the extent possible, the 


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468 Federal Register / Vol. 90, No. 2 / Friday, January 3, 2025 / Rules and Regulations 

final physical position specified for the 

test dummy. The occupant may be 

clothed in any manner. 

(3) Verify that the seat belt warnings 

function as specified in S7.5(b) and (c) 

for any combination of seat belt use (at 

any seating position), seat occupancy (at 

any seating position), removable seat 

electrical connection status (connected 

or not connected, for any removable 

seat), vehicle speed, and door status 

(open or closed, for any door), except 

that the door shall not be opened when 

the vehicle is in motion. 

Issued in Washington, DC, under authority 

delegated in 49 CFR 1.95 and part 501. 

Adam Raviv, 

Chief Counsel. 

[FR Doc. 2024–30340 Filed 1–2–25; 8:45 am] 

BILLING CODE 4910–59–P 


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