54712 Federal Register / Vol. 71, No. 180 / Monday, September 18, 2006 / Proposed Rules 

DEPARTMENT OF TRANSPORTATION 

National Highway Traffic Safety 

Administration 

49 CFR Parts 571 and 585 

[Docket No. NHTSA–2006–25801] 

RIN 2127–AJ77 

Federal Motor Vehicle Safety 

Standards; Electronic Stability Control 

Systems 

AGENCY: National Highway Traffic 

Safety Administration (NHTSA), DOT. 

ACTION: Notice of proposed rulemaking 

(NPRM). 

SUMMARY: As part of a comprehensive 

plan for reducing the serious risk of 

rollover crashes and the risk of death 

and serious injury in those crashes, this 

document proposes to establish a new 

Federal motor vehicle safety standard 

(FMVSS) No. 126 to require electronic 

stability control (ESC) systems on 

passenger cars, multipurpose vehicles, 

trucks and buses with a gross vehicle 

weight rating of 4,536 Kg (10,000 

pounds) or less. ESC systems use 

automatic computer-controlled braking 

of individual wheels to assist the driver 

in maintaining control in critical driving 

situations in which the vehicle is 

beginning to lose directional stability at 

the rear wheels (spin out) or directional 

control at the front wheels (plow out). 

Based on our own crash data studies, 

NHTSA estimates that the installation of 

ESC will reduce single-vehicle crashes 

of passenger cars by 34 percent and 

single vehicle crashes of sport utility 

vehicles (SUVs) by 59 percent, with a 

much greater reduction of rollover 

crashes. 

Preventing single-vehicle loss-ofcontrol crashes is the most effective way 

to reduce deaths resulting from rollover 

crashes. This is because most loss of 

control crashes culminate in the vehicle 

leaving the roadway, which 

dramatically increases the probability of 

a rollover. NHTSA estimates that ESC 

has the potential to prevent 71 percent 

of passenger car rollovers and 84 

percent of SUV rollovers in singlevehicle crashes. 

NHTSA estimates that ESC would 

save 5,300 to 10,300 lives and prevent 

168,000 to 252,000 injuries in all types 

of crashes annually if all light vehicles 

on the road were equipped with ESC 

systems. ESC systems would 

substantially reduce (by 4,200 to 5,400) 

of the more than 10,000 deaths each 

year on American roads resulting from 

rollover crashes. 

About 29 percent of model year (MY) 

2006 light vehicles sold in the U.S. were 

equipped with ESC, and manufacturers 

intend to increase the number of ESC 

installations in light vehicles to 71 

percent by MY 2011. This rule would 

require a 100 percent installation rate 

for ESC by MY 2012 (with exceptions 

for some vehicles manufactured in 

stages or by small volume 

manufacturers). Of the overall projected 

annual 5,300 to 10,300 highway deaths 

and 168,000 to 252,000 injuries 

prevented, we would attribute 1,536 to 

2,211 prevented fatalities (including 

1,161 to 1,445 involving rollover) to this 

proposed rulemaking, in addition to the 

prevention of 50,594 to 69,630 injuries. 

DATES: You should submit your 

comments early enough to ensure that 

Docket Management receives them not 

later than November 17, 2006. 

ADDRESSES: You may submit comments 

identified by DOT DMS Docket Number 

above by any of the following methods: 

• Web Site: http://dms.dot.gov. 

Follow the instructions for submitting 

comments on the DOT electronic docket 

site. 

• Fax: 1–202–493–2251. 

• Mail: Docket Management Facility; 

U.S. Department of Transportation, 400 

Seventh Street, SW., Nassif Building, 

Room PL–401, Washington, DC 20590 

• Hand Delivery: Room PL–401 on 

the plaza level of the Nassif Building, 

400 Seventh Street, SW., Washington, 

DC, between 9 a.m. and 5 p.m., Monday 

through Friday, except Federal 

Holidays. 

• Federal eRulemaking Portal: Go to 

http://www.regulations.gov. Follow the 

online instructions for submitting 

comments. 

Instructions: All submissions must 

include the agency name and docket 

number or Regulatory Identification 

Number (RIN) for this rulemaking. For 

detailed instructions on submitting 

comments and additional information 

on the rulemaking process, see the 

Public Participation heading of the 

Supplementary Information section of 

this document. Note that all comments 

received will be posted without change 

to http://dms.dot.gov, including any 

personal information provided. Please 

see the Privacy Act heading under 

Regulatory Notices. 

Docket: For access to the docket to 

read background documents or 

comments received, go to http:// 

dms.dot.gov at any time or to Room PL– 

401 on the plaza level of the Nassif 

Building, 400 Seventh Street, SW., 

Washington, DC, between 9 a.m. and 5 

p.m., Monday through Friday, except 

Federal Holidays. 

FOR FURTHER INFORMATION CONTACT: For 

non-legal issues, you may call Mr. 

Patrick Boyd, Office of Crash Avoidance 

Standards at (202) 366–2272. His FAX 

number is (202) 366–7002. 

For legal issues, you may call Mr. Eric 

Stas, Office of the Chief Counsel at (202) 

366–2992. His FAX number is (202) 

366–3820. 

You may send mail to both of these 

officials at National Highway Traffic 

Safety Administration, 400 Seventh 

Street, SW., Washington, DC 20590. 

SUPPLEMENTARY INFORMATION: 

Table of Contents 

I. Executive Summary 

II. Safety Problems Addressed by the 

Proposed Standard 

A. Single-Vehicle Crash and Rollover 

Statistics 

B. The Agency’s Comprehensive Response 

to Rollover 

III. Electronic Stability Control Systems 

A. How ESC Prevents Loss of Vehicle 

Control 

B. Additional Features of Some ESC 

Systems 

IV. Effectiveness of ESC 

A. Human Factors Study on the 

Effectiveness of ESC 

B. Crash Data Studies of ESC Effectiveness 

V. Agency Proposal 

A. Definition of ESC 

B. Performance Test of ESC Oversteer 

Intervention and Stability Criteria 

C. Responsiveness Criteria 

D. Other Issues 

1. ESC Off Switches 

2. ESC Activation and Malfunction 

Symbols and Telltale 

3. ESC Off Switch Symbol and Telltale 

E. Alternatives to the Agency Proposal 

VI. Leadtime 

VII. Benefits and Costs 

A. Summary 

B. ESC Benefits 

C. ESC Costs 

VIII. Public Participation 

IX. Regulatory Analyses and Notices 

I. Executive Summary 

As part of a comprehensive plan for 

reducing the serious risk of rollover 

crashes and the risk of death and serious 

injury in those crashes, this rule 

proposes to establish Federal Motor 

Vehicle Safety Standard (FMVSS) No. 

126, Electronic Stability Control 

Systems, which would require 

passenger cars, multipurpose passenger 

vehicles (MPVs), trucks, and buses that 

have a gross vehicle weight rating 

(GVWR) of 4,536 kg (10,000 pounds) or 

less to be equipped with an ESC system 

that meets the requirements of the 

standard. ESC systems use automatic, 

computer-controlled braking of 

individual wheels to assist the driver in 

maintaining control (and the vehicle’s 

intended heading) in situations where 

the vehicle is beginning to lose 

directional stability (e.g., where the 

driver misjudges the severity of a curve 


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1Pub. L. 109–59, 119 Stat. 1144 (2005). 

2Without an equipment requirement, it would be 

almost impossible to devise a single performance 

test that could not be met through some action by 

the manufacturer other than providing an ESC 

system. Even a battery of performance tests still 

might not achieve our intended results, because 

although it might necessitate installation of an ESC 

system, we expect that it would be unduly 

cumbersome for both the agency and the regulated 

community. 

3A ‘‘closed-loop algorithm’’ is a cycle of 

operations followed by a computer that includes 

automatic adjustments based on the result of 

previous operations or other changing conditions. 

or over-corrects in an emergency 

situation). In such situations (which 

occur with considerable frequency), 

intervention by the ESC system can 

assist the driver in preventing the 

vehicle from leaving the roadway, 

thereby preventing fatalities and injuries 

associated with crashes involving 

vehicle rollover or collision with 

various objects (e.g., trees, highway 

infrastructure, other vehicles). 

Based upon current estimates 

regarding the effectiveness of ESC 

systems, we believe that an ESC 

standard could save thousands of lives 

each year, providing potentially the 

greatest safety benefits produced by any 

safety device since the introduction of 

seat belts. The following discussion 

highlights the research and regulatory 

efforts that have culminated in the 

present proposal. 

Since the early 1990’s, NHTSA has 

been actively engaged in finding ways to 

address the problem of vehicle rollover, 

because crashes involving rollover are 

responsible for a disproportionate 

number of fatalities and serious injuries 

(over 10,000 of the 33,000 fatalities of 

vehicle occupants in 2004). Although 

various options were explored, the 

agency ultimately chose to add a 

rollover resistance component to its 

New Car Assessment Program (NCAP) 

consumer information program in 2001. 

In response to NCAP’s market-based 

incentives, vehicle manufacturers made 

modifications to their product lines to 

increase their vehicles’ geometric 

stability and rollover resistance by 

utilizing wider track widths (typically 

associated with passenger cars) on many 

of their newer sport utility vehicles 

(SUVs) and by making other 

improvements to truck-based SUVs 

during major redesigns (e.g., 

introduction of roll stability control). 

This approach was successful in terms 

of reducing the much higher rollover 

rate of SUVs and other high-center-ofgravity vehicles, as compared to 

passenger cars. However, manipulating 

vehicle configuration alone cannot 

entirely resolve the rollover problem 

(particularly when consumers continue 

to demand vehicles with greater 

carrying capacity and higher ground 

clearance). 

Accordingly, the agency began 

exploring technologies that could 

confront the issue of vehicle rollover 

from a different perspective or line of 

inquiry, which led to today’s proposal. 

We believe that our proposed ESC 

requirement offers a complementary 

approach that would provide substantial 

benefits to drivers of both passenger cars 

and LTVs (light trucks/vans). 

Undoubtedly, keeping vehicles from 

leaving the roadway is the best way to 

prevent deaths and injuries associated 

with rollover, as well as other types of 

crashes. Based on its crash data studies, 

NHTSA estimates that the installation of 

ESC systems will reduce single vehicle 

crashes of passenger cars by 34 percent 

and single vehicle crashes of sport 

utility vehicles (SUVs) by 59 percent. Its 

effectiveness is especially great for 

single-vehicle crashes resulting in 

rollover, where ESC systems were 

estimated to prevent 71 percent of 

passenger car rollovers and 84 percent 

of SUV rollovers in single vehicle 

crashes (see section VII). 

In short, we believe that preventing 

single-vehicle loss-of-control crashes is 

the most effective way to reduce 

rollover deaths, and we believe that ESC 

offers considerable promise in terms of 

meeting this important safety objective 

while maintaining a broad range of 

vehicle choice for consumers. In fact, 

among the agency’s ongoing and 

planned rulemakings, it is the single 

most effective way of reducing the total 

number of traffic deaths. It is also the 

most cost-effective of those rulemakings. 

We note that this proposal is 

consistent with recent congressional 

legislation contained in section 10301 of 

the Safe, Accountable, Flexible, 

Efficient Transportation Equity Act: A 

Legacy for Users of 2005 (SAFETEA–

LU).1 That provision requires the 

Secretary of Transportation to ‘‘establish 

performance criteria to reduce the 

occurrence of rollovers consistent with 

stability enhancing technologies’’ and to 

‘‘issue a proposed rule * * * by October 

1, 2006, and a final rule by April 1, 

2009.’’

The balance of this notice explains in 

detail: (1) The size of the safety problem 

(see section II); (2) how ESC systems 

would act to mitigate that safety 

problem (see section II); (3) the basics of 

ESC operation (see section III); (4) 

findings from ESC-related research (see 

section IV);(5) the specifics of our 

regulatory proposal (see section V); (6) 

lead time and phase-in requirements 

(see section VI), and (7) costs and 

benefits associated with this proposal 

(see section VII). The following section 

summarizes the key points of the 

proposal. 

A. Proposed Requirements for ESC 

Systems 

Consistent with the congressional 

mandate in section 10301 of SAFETEA–

LU, NHTSA is proposing to require all 

light vehicles to be equipped with an 

ESC system with, at the minimum, the 

capabilities of current production 

systems. We believe that a requirement 

for such ESC systems would be 

practicable in terms of both ensuring 

technological feasibility and providing 

the desired safety benefits in a costeffective manner. Although vehicle 

manufacturers have been increasing the 

share of the light vehicle fleet equipped 

with ESC, we believe that given the 

relatively high cost of this technology, a 

mandatory standard is necessary to 

maximize the safety benefits associated 

with electronic stability control, and is 

consistent with the mandate arising out 

of SAFETEA–LU. 

In order to realize these benefits, we 

have tentatively decided to require 

vehicles both to be equipped with an 

ESC system meeting definitional 

requirements and to pass a dynamic 

test. The definitional requirements 

specify the necessary elements of a 

stability control system that would be 

capable of both effective oversteer and 

understeer intervention. These 

requirements are necessary due to the 

extreme difficulty in establishing a test 

adequate to ensure the desired level of 

ESC functionality.2 The test is necessary 

to ensure that the ESC system is robust 

and meets a level of performance at least 

comparable to that of current ESC 

systems. These requirements are 

summarized below. 

• Consistent with the industry 

consensus definition of ESC contained 

in the Society of Automotive Engineers 

(SAE) Surface Vehicle Information 

Report J2564 (rev. June 2004), we are 

proposing to require vehicles covered 

under the standard to be equipped with 

an ESC system that: 

(1) Augments vehicle directional 

stability by applying and adjusting the 

vehicle’s brakes individually to induce 

correcting yaw torques to a vehicle; 

(2) Is computer-controlled, with the 

computer using a closed-loop 

algorithm 3 to limit vehicle oversteer 

and to limit vehicle understeer when 

appropriate; 


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4 ‘‘Yaw rate’’ means the rate of change of the 

vehicle’s heading angle measured in degrees/second 

of rotation about a vertical axis through the 

vehicle’s center of gravity. 

5 ‘‘Sideslip’’ means the arctangent of the lateral 

velocity of the center of gravity of the vehicle 

divided by the longitudinal velocity of the center 

of gravity. 

(3) Has a means to determine vehicle 

yaw rate 4 and to estimate its sideslip 5; 

(4) Has a means to monitor driver 

steering input, and 

(5) Is operational over the full speed 

range of the vehicle (except below a 

low-speed threshold where loss of 

control of the vehicle is unlikely). 

• The proposed ESC system as 

defined above would also be required to 

be capable of applying all four brakes 

individually and to have an algorithm 

that utilizes this capability. The system 

would also be required to be operational 

during all phases of driving, including 

acceleration, coasting, and deceleration 

(including braking), and it would be 

required to remain operational when the 

antilock brake system or traction control 

system is activated. 

• We are also proposing to require 

vehicles covered under the standard to 

meet a performance test that would 

satisfy the standard’s stability criteria 

and responsiveness criterion when 

subjected to the Sine with Dwell 

steering maneuver test. This test 

involves a vehicle coasting at an initial 

speed of 50 mph while a steering 

machine steers the vehicle with a 

steering wheel pattern as shown in 

Figure 2. The test maneuver is then 

repeated over a series of increasing 

maximum steering angles. This test 

maneuver was selected over a number of 

other alternatives, because we 

tentatively decided that it has the most 

optimal set of characteristics, including 

severity of the test, repeatability and 

reproducibility of results, and the ability 

to address lateral stability and 

responsiveness (see section V.B). 

The maneuver is severe enough to 

produce spinout for most vehicles 

without ESC. The stability criteria for 

the test measure how quickly the 

vehicle stops turning after the steering 

wheel is returned to the straight-ahead 

position. A vehicle that continues to 

turn for an extended period after the 

driver steers straight is out of control, 

which is what ESC is designed to 

prevent. The stability criteria are 

expressed in terms of the percent of the 

peak yaw rate after maximum steering 

that persists at a period of time after the 

steering wheel has been returned to 

straight ahead. They require that the 

vehicle yaw rate decrease to no more 

than 35 percent of the peak value after 

one second and that it continues to drop 

to no more than 20 percent after 1.75 

seconds. Since a vehicle that simply 

responds very little to steering 

commands could meet the stability 

criteria, a minimum responsiveness 

criterion is applied to the same test. It 

requires that the ESC-equipped vehicle 

must move laterally at least 1.83 meters 

(half a 12 foot lane width) during the 

first 1.07 seconds after the initiation of 

steering (a discontinuity in the steering 

pattern that is convenient for timing a 

measurement). 

• Because the benefits of the ESC 

system can only be realized if the 

system is functioning properly, we are 

proposing to require a telltale be 

mounted inside the occupant 

compartment in front of and in clear 

view of the driver and be identified by 

the symbol shown for ‘‘ESC Malfunction 

Telltale’’ in Table 1 of FMVSS No. 101, 

Controls and Displays. The ESC 

malfunction telltale would be required 

to illuminate not more than two minutes 

after the occurrence of one or more 

malfunctions that affect the generation 

or transmission of control or response 

signals in the vehicle’s ESC system. 

Such telltale must remain continuously 

illuminated for as long as the 

malfunction(s) exists, whenever the 

ignition locking system is in the ‘‘On’’

(‘‘Run’’) position. (Vehicle 

manufacturers would be permitted to 

use the ESC malfunction telltale in a 

flashing mode to indicate ESC 

operation.) 

• In certain circumstances, drivers 

may have legitimate reasons to 

disengage the ESC system or limit its 

ability to intervene, such as when the 

vehicle is stuck in sand/gravel or when 

the vehicle is being run on a track for 

maximum performance. Accordingly, 

under this proposal, vehicle 

manufacturers would be permitted to 

include a driver-selectable switch that 

places the ESC system in a mode in 

which it would not satisfy the 

performance requirements of the 

standard (e.g., ‘‘sport’’ mode or full-off 

mode). However, if the vehicle 

manufacturer chooses this option, it 

would be required to ensure that the 

ESC system always returns to a mode 

that satisfies the requirements of the 

standard at the initiation of each new 

ignition cycle, regardless of the mode 

the driver had previously selected. The 

manufacturer would be required to 

provide an ‘‘ESC Off’’ switch and a 

telltale that is mounted inside the 

occupant compartment in front of and 

in clear view of the driver and which is 

identified by the symbol shown for 

‘‘ESC Off’’ in Table 1 of FMVSS No. 101. 

Such telltale must remain continuously 

illuminated for as long as the ESC is in 

a mode that renders it unable to meet 

the performance requirements of the 

standard, whenever the ignition locking 

system is in the ‘‘On’’ (‘‘Run’’) position. 

• We are not proposing to require the 

ESC system to be equipped with a roll 

stability control function (or a separate 

system to that effect). Roll stability 

control systems involve relatively new 

technology, and there is currently 

insufficient data to judge the efficacy of 

such systems. However, the agency will 

continue to monitor the development of 

roll stability control systems. Vehicle 

manufacturers may supplement the ESC 

system we are proposing to require with 

a roll stability control system/feature. 

B. Leadtime and Phase-In 

In order to provide the public with 

what are expected to be the significant 

safety benefits of ESC systems as rapidly 

as possible, NHTSA is proposing to 

require all light vehicles covered by this 

standard to be equipped with a FMVSS 

No. 126-compliant ESC system by 

September 1, 2011. We are proposing 

that compliance would commence on 

September 1, 2008, which would mark 

the start of a three-year phase-in period. 

Subject to the special provisions 

discussed below, the proposed phase-in 

schedule for FMVSS No. 126 would be 

as follows: 30 percent of a vehicle 

manufacturer’s light vehicles 

manufactured during the period from 

September 1, 2008 to August 31, 2009 

would be required to comply with the 

standard; 60 percent of those 

manufactured during the period from 

September 1, 2009 to August 31, 2010; 

90 percent of those manufactured 

during the period from September 1, 

2010 to August 31, 2011, and all light 

vehicles thereafter. 

In general, we believe that it would be 

practicable for vehicle manufacturers to 

meet the requirements of the phase-in 

discussed above. We anticipate that 

vehicle manufacturers would be able to 

meet the requirements of the proposed 

standard by installing ESC systems 

currently in production, and most 

vehicle lines would likely experience 

some level of redesign over the next four 

to five years, which would provide an 

opportunity to incorporate an ESC 

system during the course of the 

manufacturer’s normal production cycle 

(see section VI for a more complete 

discussion). 

However, NHTSA is proposing to 

exclude multi-stage manufacturers and 

alterers from the requirements of the 

phase-in and to extend by one year the 

time for compliance by those 

manufacturers (i.e., until September 1, 

2012). This NPRM also proposes to 

exclude small volume manufacturers 


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6We note that carry-forward credits would not be 

permitted to be used to defer the mandatory 

compliance date of September 1, 2011 for all 

covered vehicles. 

7 In April 2006, NHTSA sent letters to seven 

vehicle manufacturers requesting voluntary 

submission of information regarding their planned 

production of ESC-equipped vehicles for model 

years 2007 to 2012. Manufacturers responded with 

product plans containing confidential information. 

These agency letters and manufacturer responses 

(with confidential information redacted) may be 

found in the docket for this rulemaking. 

(i.e., manufacturers producing less than 

5,000 vehicles for sale in the U.S. 

market in one year) from the phase-in, 

instead requiring such manufacturers to 

fully comply with the standard on 

September 1, 2011. 

Under our proposal, vehicle 

manufacturers would be permitted to 

earn carry-forward credits for compliant 

vehicles, produced in excess of the 

phase-in requirements, which are 

manufactured between the effective date 

of the final rule and the conclusion of 

the phase-in period.6

C. Anticipated Impacts of the Proposal 

As noted above, we believe that ESC 

has among the highest life-saving 

potential of any vehicle safety device 

developed in the past three decades, 

ranking with seatbelts and air bags in 

terms of importance. NHTSA estimates 

that ESC would save 5,300 to 10,300 

lives and prevent 168,000 to 252,000 

injuries in all types of crashes annuvly 

if all light vehicles on the road were 

equipped with ESC systems. A large 

portion of these savings would come 

from rollover crashes. ESC systems 

would substantially reduce (by 4,200 to 

5,400) of the more than 10,000 deaths 

each year on American roads resulting 

from rollover crashes. 

About 29 percent of model year (MY) 

2006 light vehicles sold in the U.S. were 

equipped with ESC, and manufacturers 

intend to increase the number of ESC 

installations in light vehicles to 71 

percent by MY 2011.7 This rule would 

require a 100 percent installation rate 

for ESC by MY 2012 (with exceptions 

for some vehicles manufactured in 

stages or by small volume 

manufacturers). As the discussion below 

demonstrates, ESC has very significant 

life-saving and injury-preventing 

potential in absolute terms, but it does 

so in a very cost-effective manner vis-a ́- 

vis other agency rulemakings. ESC offers 

consistently strong benefits and costeffectiveness across all types of light 

vehicles, including passenger cars, 

SUVs, vans, and pick-up trucks. 

Of the 5,300 to 10,300 highway deaths 

and 168,000 to 252,000 MAIS 1–5 

injuries which we project will be 

prevented annually for all types of 

crashes once all light vehicles on the 

road are equipped with ESC, we would 

attribute 1,536 to 2,211 prevented 

fatalities (including 1,161 to 1,445 

involving rollover) to this proposed 

rulemaking, in addition to the 

prevention of 50,594 to 69,630 injuries. 

This compares favorably with the 

Regulatory Impact Analyses for other 

important rulemakings such as FMVSS 

No. 208 mandatory air bags (1,964 to 

3,670 lives saved), FMVSS No. 214 side 

impact protection (690 to 1,030 lives 

saved), and FMVSS No. 201 upper 

interior head impact protection (870 to 

1,050 lives saved). (See section VII, 

Benefits and Costs of this notice and the 

Preliminary Regulatory Impact Analysis 

submitted to the docket for this 

rulemaking). In addition, the agency 

estimates that property damage and 

travel delay costs would be reduced by 

$260 to $453 million annually. 

The agency estimates that the 

production-weighted, average cost per 

vehicle to meet the proposed standard’s 

requirements would be $58 ($90.3 per 

passenger car and $29.2 per light truck). 

These are incremental costs over the MY 

2011 installation of ABS, which is 

expected to be installed in almost 93 

percent of the light vehicle fleet, and 

ESC, which is expected to be installed 

in 71 percent of the light vehicle fleet. 

Vehicle costs are estimated to be $368 

(in 2005$) for anti-lock brakes (ABS) 

and an additional $111 for ESC, for a 

total system cost of $479 per vehicle. 

Currently, every vehicle that is 

equipped with ESC, is also equipped 

with ABS and traction control. 

However, the agency believes that 

traction control is a convenience 

feature. Accordingly, it is not required 

by this proposal. We also assumed an 

annual production of 17 million light 

vehicles (9 million light trucks and 8 

million passenger cars). Thus, the total 

annual vehicle cost of this regulation, 

corresponding to ESC installation 

beyond manufacturers’ planned 

production, is expected to be 

approximately $985 million. 

In terms of cost-effectiveness, this 

proposal for passenger cars and light 

trucks would save 1,536 to 2,211 lives 

and prevent 50,594 to 69,630 injuries at 

a cost of $0.19 to $0.32 million per 

equivalent life saved at a 3 percent 

discount rate and $0.27 to $0.43 at a 7 

percent discount rate. Again, the costeffectiveness for ESC compares 

favorably with the Regulatory Impact 

Analyses for other important 

rulemakings such as FMVSS No. 202 

head restraints safety improvement 

($2.61 million per life saved), FMVSS 

No. 208 center seat shoulder belts ($3.39 

to $5.92 million per life saved), FMVSS 

No. 208 advanced air bags ($1.9 to $9.0 

million per life saved), and FMVSS No. 

301 fuel system integrity upgrade ($1.96 

to $5.13 million per life saved). 

We note that the costs for passenger 

cars are higher because a greater portion 

of those vehicles require installation of 

ABS in addition to ESC. Nevertheless, 

the proposal remains highly costeffective even when passenger cars are 

considered alone. The passenger car 

portion of the proposal would save 956 

lives and prevent 34,902 injuries at a 

cost of $0.35 million per equivalent life 

saved at a 3 percent discount rate and 

$0.47 at a 7 percent discount rate. 

Therefore, the agency deemed it 

appropriate to make the proposed 

standard applicable to all light vehicles, 

because such approach makes sense 

from both a safety and cost standpoint. 

II. Safety Problems Addressed by the 

Proposed Standard 

Crash data studies conducted in the 

U.S., Europe and Japan indicate that 

ESC is very effective in reducing singlevehicle crashes. Studies of the behavior 

of ordinary drivers in critical situations 

using the National Advanced Driving 

Simulator also show a very large 

reduction in instances of loss of control 

when the vehicle is equipped with ESC. 

Based on its crash data studies, NHTSA 

estimates that ESC will reduce single 

vehicle crashes of passenger cars by 34 

percent and single vehicle crashes of 

SUVs by 59 percent. NHTSA’s latest 

crash data study also shows that ESC is 

most effective in reducing single-vehicle 

crashes that result in rollover. ESC is 

estimated to prevent 71 percent of 

passenger car rollovers and 84 percent 

of SUV rollovers in single vehicle 

crashes. It is also estimated to reduce 

some multi-vehicle crashes but at a 

much lower rate than its effect on single 

vehicle crashes. 

A. Single-Vehicle Crash and Rollover 

Statistics 

About one in seven light vehicles 

involved in police-reported crashes 

collide with something other than 

another vehicle. However, the 

proportion of these single-vehicle 

crashes increases steadily with 

increasing crash severity, and almost 

half of serious and fatal injuries occur 

in single-vehicle crashes. We can 

describe the relationship between crash 

severity and the number of vehicles 

involved in the crash using information 

from the agency’s crash data programs. 

We limit our discussion here to light 

vehicles, which consist of (1) passenger 

cars and (2) multipurpose passenger 

vehicles, trucks and buses under 4,536 


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8For brevity, we use the term light trucks in this 

document to refer to multipurpose passenger 

vehicles, such as vans, minivans, and SUVs, trucks 

and buses under 4,536 kilograms (10,000 pounds) 

GVWR. 9See Docket Number NHTSA 2003–14622–1. 

kilograms (10,000 pounds) gross vehicle 

weight rating (GVWR).8

The 2000–2004 data from the National 

Automotive Sampling System (NASS) 

Crashworthiness Data System (CDS) and 

2004 data from the Fatality Analysis 

Reporting System (FARS) were 

combined to estimate the current target 

population for this rulemaking. It 

includes 28,252 people who were killed 

as occupants of light vehicles. Over half 

of these (15,007) occurred in singlevehicle crashes. Of these, 8,460 

occurred in rollovers. About 1.1 million 

injuries (AIS 1–5) occurred in crashes 

that could be affected by ESC, almost 

500,000 in single vehicle crashes (of 

which almost half were in rollovers). 

Multi-vehicle crashes that could be 

affected by ESC accounted for 13,245 

fatalities and almost 600,000 injuries. 

Rollover crashes are complex events 

that reflect the interaction of driver, 

road, vehicle, and environmental 

factors. We can describe the relationship 

between these factors and the risk of 

rollover using information from the 

agency’s crash data programs. 

According to 2004 data from FARS, 

10,555 people were killed as occupants 

in light vehicle rollover crashes, which 

represents 33 percent of all occupants 

killed that year in crashes. Of those, 

8,567 were killed in single-vehicle 

rollover crashes. Seventy-four percent of 

the people who died in single-vehicle 

rollover crashes were not using a seat 

belt, and 61 percent were partially or 

completely ejected from the vehicle 

(including 50 percent who were 

completely ejected). FARS shows that 

55 percent of light vehicle occupant 

fatalities in single-vehicle crashes 

involved a rollover event. 

Using data from the 2000–2004 NASS 

CDS files, we estimate that 280,000 light 

vehicles were towed from a policereported rollover crash each year (on 

average), and that 29,000 occupants of 

these vehicles were seriously injured. Of 

these 280,000 light vehicle rollover 

crashes, 230,000 were single-vehicle 

crashes. Sixty-two percent of those 

people who suffered a serious injury in 

a single-vehicle tow-away rollover crash 

were not using a seat belt, and 52 

percent were partially or completely 

ejected (including 41 percent who were 

completely ejected). Estimates from 

NASS CDS indicate that 82 percent of 

tow-away rollovers were single-vehicle 

crashes, and that 88 percent (202,000) of 

the single-vehicle rollover crashes 

occurred after the vehicle left the 

roadway. An audit of 1992–96 NASS 

CDS data showed that about 95 percent 

of rollovers in single-vehicle crashes 

were tripped by mechanisms such as 

curbs, soft soil, pot holes, guard rails, 

and wheel rims digging into the 

pavement, rather than by tire/road 

interface friction as in the case of 

untripped rollover events. 

B. The Agency’s Comprehensive 

Response to Rollover 

As mentioned above, this proposal for 

ESC is part of the agency’s 

comprehensive plan to address the issue 

of vehicle rollover. The following 

provides background on NHTSA’s 

comprehensive plan to reduce rollover 

crashes. In 2002, the agency formed an 

Integrated Project Team (IPT) to 

examine the rollover problem and make 

recommendations on how to reduce 

rollovers and improve safety when 

rollovers nevertheless occur. In June 

2003, based on the work of the team, the 

agency published a report entitled, 

‘‘Initiatives to Address the Mitigation of 

Vehicle Rollover.’’ 9 The report 

recommended improving vehicle 

stability, ejection mitigation, roof crush 

resistance, as well as road improvement 

and behavioral strategies aimed at 

consumer education. 

Since then, the agency has been 

working to implement these 

recommendations as part of it 

comprehensive agency plan for reducing 

the serious risk of rollover crashes and 

the risk of death and serious injury 

when rollover crashes do occur. It is 

evident that the most effective way to 

reduce deaths and injuries in rollover 

crashes is to prevent the rollover crash 

from occurring. This proposal to adopt 

a new Federal motor vehicle safety 

standard for electronic stability control 

systems is one part of that 

comprehensive agency plan. 

Moreover, we note that the agency 

also published a notice of proposed 

rulemaking in the Federal Register in 

August 2005, seeking to upgrade our 

safety standard on roof crush resistance 

(FMVSS No. 216); that notice, like the 

present one, contains an in-depth 

discussion of the rollover problem and 

the countermeasures which the agency 

intends to pursue as part of its 

comprehensive response to the rollover 

problem (see 70 FR 49223 (August 23, 

2005)). 

III. Electronic Stability Control Systems 

Although Electronic Stability Control 

(ESC) systems are known by many 

different trade names such as Vehicle 

Stability Control (VSC), Electronic 

Stability Program (ESP), StabiliTrak and 

Vehicle Stability Enhancement (VSE), 

their function and performance are 

similar. They are systems that uses 

computer control of individual wheel 

brakes to help the driver maintain 

control of the vehicle during extreme 

maneuvers by keeping the vehicle 

headed in the direction the driver is 

steering even when the vehicle nears or 

reaches the limits of road traction. 

When a driver attempts an ‘‘extreme 

maneuver’’ (e.g., one initiated to avoid 

a crash or due to misjudgment of the 

severity of a curve), the driver may lose 

control if the vehicle responds 

differently as it nears the limits of road 

traction than it does during ordinary 

driving. The driver’s loss of control can 

result in either the rear of the vehicle 

‘‘spinning out’’ or the front of the 

vehicle ‘‘plowing out.’’ As long as there 

is sufficient road traction, a highly 

skilled driver may be able to maintain 

control in many extreme maneuvers 

using countersteering (i.e., momentarily 

turning away from the intended 

direction) and other techniques. 

However, average drivers in a panic 

situation in which the vehicle beginning 

to spin out would be unlikely to 

countersteer to regain control. 

ESC uses automatic braking of 

individual wheels to adjust the vehicle’s 

heading if it departs from the direction 

the driver is steering. Thus, it prevents 

the heading from changing too quickly 

(spinning out) or not quickly enough 

(plowing out). Although it cannot 

increase the available traction, ESC 

affords the driver the maximum 

possibility of keeping the vehicle under 

control and on the road in an emergency 

maneuver using just the natural reaction 

of steering in the intended direction. 

Keeping the vehicle on the road 

prevents single-vehicle crashes, which 

are the circumstances that lead to most 

rollovers. However, if the speed is 

simply too great for the available road 

traction, even a vehicle with ESC will 

unavoidably drift off the road (but not 

spin out). Furthermore, ESC cannot 

prevent road departures due to driver 

inattention or drowsiness rather than 

loss of control. 

A. How ESC Prevents Loss of Vehicle 

Control 

The following explanation of ESC 

operation illustrates the basic principle 

of yaw stability control, but it does not 

attempt to explain advanced 

refinements of the yaw control strategy 

described below that use vehicle 

sideslip (lateral sliding that may not 

alter yaw rate) to optimize performance 

on slippery pavements. 


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Federal Register / Vol. 71, No. 180 / Monday, September 18, 2006 / Proposed Rules 54717 

An ESC system maintains what is 

known as ‘‘yaw’’ (or heading) control by 

determining the driver’s intended 

heading, measuring the vehicle’s actual 

response, and automatically turning the 

vehicle if its response does not match 

the driver’s intention. However, with 

ESC, turning is accomplished by 

applying counter torques from the 

braking system rather than from steering 

input. 

Speed and steering angle 

measurements are used to determine the 

driver’s intended heading. The vehicle 

response is measured in terms of lateral 

acceleration and yaw rate by onboard 

sensors. If the vehicle is responding in 

a manner corresponding to driver input, 

the yaw rate will be in balance with the 

speed and lateral acceleration. 

The concept of ‘‘yaw rate’’ can be 

illustrated by imaging the view from 

above of a car following a large circle 

painted on a parking lot. One is looking 

at the top of the roof of the vehicle and 

seeing the circle. If the car starts in a 

heading pointed north and drives half 

way around circle, its new heading is 

south. Its yaw angle has changed 180 

degrees. If it takes 10 seconds to go half 

way around the circle, the ‘‘yaw rate’’ is 

180 degrees per 10 seconds or 18 deg/ 

sec. If the speed stays the same, the car 

is constantly rotating at a rate of 18 deg/ 

sec around a vertical axis that can be 

imagined as piercing its roof. If the 

speed is doubled, the yaw rate increases 

to 36 deg/sec. 

While driving in a circle, the driver 

notices that he must hold the steering 

wheel tightly to avoid sliding toward 

the passenger seat. The bracing force is 

necessary to overcome the lateral 

acceleration that is caused by the car 

following the curve. The lateral 

acceleration is also measured by the 

ESC system. When the speed is doubled 

the lateral acceleration increases by a 

factor of four if the vehicle follows the 

same circle. There is a fixed physical 

relationship between the car’s speed, 

the radius of its circular path, and its 

lateral acceleration. 

The ESC system uses this information 

as follows: Since the ESC system 

measures the car’s speed and its lateral 

acceleration, it can compute the radius 

of the circle. Since it then has the radius 

of the circle and the car’s speed, the ESC 

system can compute the correct yaw rate 

for a car following the path. Of course, 

the system includes a yaw rate sensor, 

and it compares the actual measured 

yaw rate of the car to that computed for 

the path the car is following. If the 

computed and measured yaw rates 

begin to diverge as the car that is trying 

to follow the circle speeds up, it means 

the driver is beginning to lose control, 

even if the driver cannot yet sense it. 

Soon, an unassisted vehicle would have 

a heading significantly different from 

the desired path and would be out of 

control either by oversteering (spinning 

out) or understeering. 

When the ESC system detects an 

imbalance between the measured yaw 

rate of a vehicle and the path defined by 

the vehicle’s speed and lateral 

acceleration, the ESC system 

automatically intervenes to turn the 

vehicle. The automatic turning of the 

vehicle is accomplished by uneven 

brake application rather than by steering 

wheel movement. If only one wheel is 

braked, the uneven brake force will 

cause the vehicle’s heading to change. 

Figure 1 shows the action of ESC using 

single wheel braking to correct the onset 

of oversteering or understeering. (Please 

note that all Figures discussed in this 

preamble may be found at the end of the 

preamble, immediately preceding the 

proposed regulatory text.) 

• Oversteering. In Figure 1 (bottom 

panel), the vehicle has entered a left 

curve that is extreme for the speed it is 

traveling. The rear of the vehicle begins 

to slide which would lead to a vehicle 

without ESC turning sideways (or 

‘‘spinning out’’) unless the driver 

expertly countersteers. In a vehicle 

equipped with ESC, the system 

immediately detects that the vehicle’s 

heading is changing more quickly than 

appropriate for the driver’s intended 

path (i.e., the yaw rate is too high). It 

momentarily applies the right front 

brake to turn the heading of the vehicle 

back to the correct path. The action 

happens quickly so that the driver does 

not perceive the need for steering 

corrections. Even if the driver brakes 

because the curve is sharper than 

anticipated, the system is still capable of 

generating uneven braking if necessary 

to correct the heading. 

• Understeering. Figure 1 (top panel) 

shows a similar situation faced by a 

vehicle whose response as it nears the 

limits of road traction is to slide at the 

front (‘‘plowing out’’ or understeering) 

rather than oversteering. In this 

situation, the ESC system rapidly 

detects that the vehicle’s heading is 

changing less quickly than appropriate 

for the driver’s intended path (i.e., the 

yaw rate is too low). It momentarily 

applies the left rear brake to turn the 

heading of the vehicle back to the 

correct path. 

While Figure 1 may suggest that 

particular vehicles go out of control as 

either vehicles prone to oversteer or 

vehicles prone to understeer, it is just as 

likely that a given vehicle could require 

both understeer and oversteer 

interventions during progressive phases 

of a complex avoidance maneuver such 

as a double lane change. 

Although ESC cannot change the tire/ 

road friction conditions the driver is 

confronted with in a critical situation, 

there are clear reasons to expect it to 

reduce loss-of-control crashes, as 

discussed below. 

In vehicles without ESC, the response 

of the vehicle to steering inputs changes 

as the vehicle nears the limits of road 

traction. All of the experience of the 

average driver is in operating the 

vehicle in its ‘‘linear range’’, i.e., the 

range of lateral acceleration in which a 

given steering wheel movement 

produces a proportional change in the 

vehicle’s heading. The driver merely 

turns the wheel the expected amount to 

produce the desired heading. 

Adjustments in heading are easy to 

achieve because the vehicle’s response 

is proportional to the driver’s steering 

input, and there is very little lag time 

between input and response. The car is 

traveling in the direction it is pointed, 

and the driver feels in control. However, 

at lateral accelerations above about onehalf ‘‘g’’ on dry pavement for ordinary 

vehicles, the relationship between the 

driver’s steering input and the vehicle’s 

response changes (toward oversteer or 

understeer), and the lag time of the 

vehicle response can lengthen. When a 

driver encounters these changes during 

a panic situation, it adds to the 

likelihood that the driver will loose 

control and crash because the familiar 

actions learned by driving in the linear 

range would not be the correct steering 

actions. 

However, ordinary linear range 

driving skills are much more likely to be 

adequate for a driver of a vehicle with 

ESC to avoid loss of control in a panic 

situation. By monitoring yaw rate and 

sideslip, ESC can intervene early in the 

impending loss-of-control situation with 

the appropriate brake forces necessary 

to restore yaw stability before the driver 

would attempt an over correction or 

other error. The net effect of ESC is that 

the driver’s ordinary driving actions 

learned in linear range driving are the 

correct actions to control the vehicle in 

an emergency. Also, the vehicle will not 

change its heading from the desired 

path in a way that would induce further 

panic in a driver facing a critical 

situation. Studies using a driving 

simulator, discussed in Section IV, 

demonstrate that ordinary drivers are 

much less likely to lose control of a 

vehicle with ESC when faced with a 

critical situation. 

Besides allowing drivers to cope with 

emergency maneuvers and slippery 

pavement using only ‘‘linear range’’

skills, ESC provides more powerful 


jlentini on PROD1PC65 with PROPOSAL2
54718 Federal Register / Vol. 71, No. 180 / Monday, September 18, 2006 / Proposed Rules 

10Liebemann et al., (2005) Safety and 

Performance Enhancement: The Bosch Electronic 

Stability Control (ESP), 19th International 

Technical Conference on the Enhanced Safety of 

Vehicles (ESV), Washington, DC. 

11Aga M, Okada A. (2003) Analysis of Vehicle 

Stability Control (VSC)’s Effectiveness from 

Accident Data, 18th International Technical 

Conference on the Enhanced Safety of Vehicles 

(ESV), Nagoya. 

Dang, J. (2004) Preliminary Results Analyzing 

Effectiveness of Electronic Stability Control (ESC) 

Systems, Report No. DOT HS 809 790. U.S. Dept. 

of Transportation, Washington, DC. 

Farmer, C. (2004) Effect of Electronic Stability 

Control on Automobile Crash Risk, Traffic Injury 

Prevention Vol 5:317–325. 

Kreiss J-P, et al. (2005) The Effectiveness of 

Primary Safety Features in Passenger Cars in 

Germany. 19th International Technical Conference 

on the Enhanced Safety of Vehicles (ESV), 

Washington, DC 

Lie A., et al. (2005) The Effectiveness of ESC 

(Electronic Stability Control) in Reducing Real Life 

Crashes and Injuries. 19th International Technical 

Conference on the Enhanced Safety of Vehicles 

(ESV), Washington, DC. 

control interventions than those 

available to even expert drivers of nonESC vehicles. For all practical purposes, 

the yaw control actions with non-ESC 

vehicles are limited to steering. 

However, as the tires approach the 

maximum lateral force sustainable 

under the available pavement friction, 

the yaw moment generated by a given 

increment of steering angle is much less 

than at the low lateral forces occurring 

in regular driving.10. This means that as 

the vehicle approaches its maximum 

cornering capability, the ability of the 

steering system to turn the vehicle is 

greatly diminished, even in the hands of 

an expert driver. ESC creates the yaw 

moment to turn the vehicle using 

braking at an individual wheel rather 

than the steering system. This 

intervention remains powerful even at 

limits of tire traction because both the 

braking force of the individual tire and 

the reduction of lateral force that 

accompanies the braking force act to 

create the desired yaw moment. 

Therefore, ESC can be especially 

beneficial on slippery surfaces. While a 

vehicle’s possibility of staying on the 

road in a critical maneuver ultimately is 

limited by the tire/pavement friction, 

ESC maximizes an ordinary driver’s 

ability to use the available friction. 

B. Additional Features of Some ESC 

Systems 

In addition to the basic operation of 

‘‘yaw stability control’’, many ESC 

systems include additional features. For 

example, most systems reduce engine 

power during intervention to slow the 

vehicle and give it a better chance of 

being able to stay on the intended path 

after its heading has been corrected. 

Other ESC systems may go further by 

performing high deceleration automatic 

braking at all four wheels. Of course, 

such braking would be performed 

unevenly side to side so that the same 

net yaw torque or ‘‘turning force’’ would 

be applied to the vehicle as in the basic 

case of single-wheel braking. 

ESC systems used on vehicles with a 

high center of gravity (c.g.), such as 

SUVs, are often programmed to perform 

an additional function known as ‘‘roll 

stability control.’’ Roll stability control 

(RSC) is a direct countermeasure for onpavement rollover crashes of high c.g. 

vehicles. Some RSC systems measure 

the roll angle of the vehicle using an 

additional roll rate sensor to determine 

if the vehicle is in danger of tipping up. 

Other systems rely on the existing ESC 

sensors for steering angle, speed, and 

lateral acceleration, along with 

knowledge of vehicle-specific 

characteristics to estimate whether the 

vehicle is in danger of tipping up. 

Regardless of the method used to 

detect the risk of tip-up, the various 

types of roll stability control intervene 

in the same way. Specifically, they 

intervene by reducing lateral 

acceleration which is the cause of the 

roll motion of the vehicle on its 

suspension, thus preventing the 

possibility of it rolling so much that the 

inside wheels may lift off the pavement. 

The intervention is performed the same 

way as the oversteer intervention shown 

in the Figure 1. The outside front brake 

is applied heavily to turn the vehicle 

toward a path of less curvature and, 

therefore, less lateral acceleration. 

The difference between a roll stability 

control intervention and an oversteer 

intervention by the ESC system 

operating in the basic yaw stability 

control mode is the triggering 

circumstance. The oversteer 

intervention occurs when the vehicle’s 

excessive yaw rate indicates that its 

heading is departing from the driver’s 

intended path, but the roll stability 

control intervention occurs when there 

is a risk the vehicle could roll over. 

Thus, the roll stability control 

intervention occurs when the vehicle is 

still following the driver’s intended 

path. The obvious trade-off of roll 

stability control is that the vehicle must 

depart to some extent from the driver’s 

intended path in order to reduce the 

lateral acceleration from the level that 

could cause tip-up. 

If the determination of impending 

rollover that triggers the roll stability 

intervention is very certain, then the 

possibility of the vehicle leaving the 

roadway as a result of the roll stability 

intervention represents a lower relative 

risk to the driver. Obviously, systems 

that intervene only when absolutely 

necessary and then with the minimum 

loss of lateral acceleration to prevent 

rollover are the most effective. However, 

roll stability control is a new technology 

that is still evolving. Roll stability 

control is not a subject of this 

rulemaking because it is too soon for 

actual crash statistics to illuminate its 

practical effect on crash reduction. 

IV. Effectiveness of ESC 

Electronic stability control can 

directly reduce a vehicle’s susceptibility 

to on-road untripped rollovers as 

measured by the ‘‘fishhook’’ test that is 

part of NHTSA’s NCAP rollover rating 

program. The direct effect is mostly 

limited to untripped rollovers on paved 

surfaces. However, untripped on-road 

rollovers are a relatively infrequent type 

of rollover crash. In contrast, the vast 

majority of rollover crashes occur when 

a vehicle runs off the road and strikes 

a tripping mechanism such as soft soil, 

a ditch, a curb or a guardrail. 

We expect that requiring ESC to be 

installed on light trucks and passenger 

cars would result in a large reduction in 

the number of rollover crashes by 

greatly reducing the number of singlevehicle crashes. As noted previously, 

over 80 percent of rollovers are the 

result of a single-vehicle crash. The 

purpose of ESC is to assist the driver in 

keeping the vehicle on the road during 

impending loss-of-control situations. In 

this way, it can prevent the exposure of 

vehicles to off-road tripping 

mechanisms. We note, however, that 

this yaw stability function of ESC is not 

direct ‘‘rollover resistance’’ and cannot 

be measured by the NCAP rollover 

resistance rating. 

Although ESC is an indirect 

countermeasure to prevent rollover 

crashes, we believe it is the most 

powerful countermeasure available to 

address this serious risk. Effectiveness 

studies by NHTSA and others 

worldwide 11 estimate that ESC reduces 

single vehicle crashes by at least a third 

in passenger cars and perhaps reduces 

loss-of-control crashes (e.g., road 

departures leading to rollovers) by an 

even greater amount. In fact, NHTSA’s 

latest data study that is discussed in this 

section found a reduction in singlevehicle crashes leading to rollover of 71 

percent for passenger cars and 84 

percent for SUVs. Thus, ESC can reduce 

the numbers of rollovers of all vehicles, 

including lower center of gravity 

vehicles (e.g., passenger cars, minivans 

and two-wheel drive pickup trucks), as 

well as of the higher center of gravity 

vehicle types (e.g., SUVs and four-wheel 

drive pickup trucks). ESC can affect 

both crashes that would have resulted in 

rollover as well as other types of crashes 


jlentini on PROD1PC65 with PROPOSAL2
Federal Register / Vol. 71, No. 180 / Monday, September 18, 2006 / Proposed Rules 54719 

12Papelis et al. (2004) Study of ESC Assisted 

Driver Performance Using a Driving Simulator, 

Report No. N04–003–PR, University of Iowa. 

13See Footnote 10. 

14 Dang, J. (2004) Preliminary Results Analyzing 

Effectiveness of Electronic Stability Control (ESC) 

Systems, Report No. DOT HS 809 790. U.S. Dept. 

of Transportation, Washington, DC. 

15 Dang, J. (2006) Statistical Analysis of The 

Effectiveness of Electronic Stability Control (ESC) 

Systems, U.S. Dept. of Transportation, Washington, 

DC (publication pending peer review). A draft 

version of this report, as supplied to peer reviewers, 

has been placed in the docket for this rulemaking. 

(e.g., road departures resulting in 

impacts) that result in deaths and 

injuries. 

A. Human Factors Study on the 

Effectiveness of ESC 

A study by the University of Iowa 

using the National Advanced Driving 

Simulator demonstrated the effect of 

ESC on the ability of ordinary drivers to 

maintain control in critical situations.12

A sample of 120 drivers equally divided 

between men and women and between 

three age groups (18–25, 30–40, and 55–

65) was subjected to the following three 

critical driving scenarios. The 

‘‘Incursion Scenario’’ forced drivers to 

attempt a double lane change at high 

speed (65 mph speed limit signs) by 

presenting them first with a vehicle that 

suddenly backs into their lane from a 

driveway and then with another vehicle 

driving toward them in the left lane. 

The ‘‘Curve Departure Scenario’’

presented drivers with a constant radius 

curve that was uneventful at the posted 

speed limit of 65 mph followed by 

another curve that appeared to be 

similar but that had a decreasing radius 

that was not evident upon entry. The 

‘‘Wind Gust Scenario’’ presented drivers 

with a sudden lateral wind gust of short 

duration that pushed the drivers toward 

a lane of oncoming traffic. The 120 

drivers were further divided evenly 

between two vehicles, a SUV and a 

midsize sedan. Half the drivers of each 

vehicle drove with ESC enabled, and 

half drove with ESC disabled. 

In 50 of the 179 test runs performed 

in a vehicle without ESC, the driver lost 

control. In contrast, in only six of the 

179 test runs performed in a vehicle 

with ESC, did the driver lose control. 

One test run in each ESC status had to 

be aborted. These results demonstrate 

an 88 percent reduction in loss-ofcontrol crashes when ESC was engaged. 

The study also concluded that the 

presence of an ESC system helped 

reduce loss of control regardless of age 

or gender, and that the benefit was 

substantially the same for the different 

driver subgroups in the study. Because 

of the obvious danger to participants, an 

experiment like this cannot be 

performed safely with real vehicles on 

real roads. However, the National 

Advanced Driver Simulator provides 

extraordinary verisimilitude with the 

driver sitting in a real vehicle, seeing a 

360-degree scene and experiencing the 

linear and angular accelerations and 

sounds that would occur in actual 

driving of the specific vehicle. 

B. Crash Data Studies of ESC 

Effectiveness 

There have been a number of studies 

of ESC effectiveness in Europe and 

Japan beginning in 2003 13. All of them 

have shown large potential reductions 

in single vehicle crashes as a result of 

ESC. However, the sample sizes of 

crashes of vehicles new enough to have 

ESC tended to be small in these studies. 

A preliminary NHTSA study published 

in September 2004 14 of crash data from 

1997–2003 found ESC to be effective in 

reducing single-vehicle crashes, 

including rollover. Among vehicles in 

the study, the results suggested that ESC 

reduced single vehicle crashes in 

passenger cars by 35 percent and in 

SUVs by 67 percent. In October 2004, 

the Insurance Institute for Highway 

Safety (IIHS) released the results of a 

study of the effectiveness of ESC in 

preventing crashes of cars and SUVs. 

The IIHS found that ESC is most 

effective in reducing fatal single-vehicle 

crashes, reducing such crashes by 56 

percent. NHTSA’s later peer-reviewed 

study 15 of ESC effectiveness found that 

that ESC reduced single vehicle crashes 

in passenger cars by 34 percent and in 

SUVs by 59 percent, and that its 

effectiveness was greatest in reducing 

single vehicle crashes resulting in 

rollover (71 percent reduction for 

passenger cars and an 84 percent 

reduction for SUVs). It also found 

reductions in fatal single-vehicle 

crashes and fatal single-vehicle rollover 

crashes that were commensurate with 

the overall crash reductions cited. ESC 

reduced fatal single-vehicle crashes in 

passenger cars by 35 percent and in 

SUVs by 67 percent and reduced fatal 

single-vehicle crashes involving rollover 

by 69 percent in passenger cars and 88 

percent in SUVs. 

(a) NHTSA’s Preliminary Study 

In September, 2004, NHTSA issued an 

evaluation note on the Preliminary 

Results Analyzing the Effectiveness of 

Electronic Stability Control (ESC) 

Systems. The study evaluated the 

effectiveness of ESC in reducing single 

vehicle crashes in various domestic and 

imported cars and SUVs. It was based 

on Fatality Analysis Reporting System 

(FARS) data from calendar years 1997–

2003 and crash data from five States that 

reported partial Vehicle Identification 

Number (VIN) information in their data 

files (Florida, Illinois, Maryland, 

Missouri, and Utah) from calendar years 

1997–2002. The data were limited to 

mostly luxury vehicles because ESC first 

became available in 1997 in luxury 

vehicles such as Mercedes-Benz and 

BMW. The analysis compared specific 

make/models of passenger cars and 

SUVs with ESC versus earlier versions 

of the same make/models, using multivehicle crash involvements as a control 

group. 

The passenger car sample consisted of 

mainly Mercedes-Benz and BMW 

models (61 percent). Mercedes-Benz 

installed ESC in certain luxury models 

in 1997 and had made it standard 

equipment in all their models (except 

one) by 2000. BMW also installed ESC 

in certain 5, 7, and 8 series models as 

early as 1997 and had made it standard 

equipment in all their models by 2001. 

The passenger car sample also included 

some luxury GM cars, which constituted 

23 percent of the sample, and a few cars 

from other manufacturers. GM cars 

where ESC was offered as standard 

equipment are the Buick Park Avenue 

Ultra, the Cadillac DeVille, Seville STS 

and SLS, the Oldsmobile Aurora, the 

Pontiac Bonneville SSE and SSEi, and 

the Chevrolet Corvette. The SUV make/ 

models in the study with ESC include 

Mercedes-Benz (ML320, ML350, ML430, 

ML500, G500, G55 AMG), Toyota 

(4Runner, Landcruiser), and Lexus 

(RX300, LX470). 

The first set of analyses used multivehicle crash involvements as a control 

group, essentially assuming that ESC 

has no effect on multi-vehicle crashes. 

Specific make/models with ESC were 

compared with earlier versions of 

similar make/models using multivehicle crash involvements as a control 

group, creating 2x2 contingency tables 

as shown in Tables 1 and 2. The study 

found that single vehicle crashes were 

reduced by 

1 ¥ {(699/1483)/(14090/19444)} = 35 

percent 

for passenger cars and by 67 percent for 

SUVs (Table 1). Similarly, fatal single 

vehicle crashes were reduced by 30 

percent in cars and by 63 percent in 

SUVs (Table 2). Reductions of single 

vehicle crashes in passenger cars and 

SUVs were statistically significant at the 

.01 level, as evidenced by chi-square 

statistics exceeding 6.64 in each 2×2 

contingency table (Table 1). Reductions 

of fatal single vehicle crashes are 

statistically significant at the .01 level in 

SUVs and at the .05 level in passenger 


jlentini on PROD1PC65 with PROPOSAL2
54720 Federal Register / Vol. 71, No. 180 / Monday, September 18, 2006 / Proposed Rules 

cars with chi-square statistic greater 

than 3.84 (Table 2). 

TABLE 1.—EFFECTIVENESS OF ESC IN REDUCING SINGLE VEHICLE CRASHES IN PASSENGER CARS AND SUVS

[Preliminary Study with 1997–2002 crash data from five States] 

Single 

Vehicle 

Crashes 

Multi-Vehicle 

Crashes 

(control group) 

Passenger Cars: 

No ESC .............................................................................................................................................................. 1483 ............. 19444 

ESC .................................................................................................................................................................... 699 ............... 14090 

Percent reduction in single vehicle crashes in passenger cars with ESC ........................................................ 35% .............. ........................

Approximate 95 percent confidence bounds ..................................................................................................... 29% to 41% ........................

Chi-square value ................................................................................................................................................ 84.1 .............. ........................

SUVs: 

No ESC .............................................................................................................................................................. 512 ............... 6510 

ESC .................................................................................................................................................................... 95 ................. 3661 

Percent reduction in single vehicle crashes in SUVs with ESC ........................................................................ 67% .............. ........................

Approximate 95 percent confidence bounds ..................................................................................................... 60% to 74% ........................

Chi-square value ................................................................................................................................................ 104.4 ............ ........................

TABLE 2.—EFFECTIVENESS OF ESC IN REDUCING FATAL SINGLE VEHICLE CRASHES IN PASSENGER CARS AND SUVS

[Preliminary Study with 1997–2003 FARS data] 

Fatal Single 

Vehicle 

Crashes 

Fatal MultiVehicle 

Crashes 

(control group) 

Passenger Cars: 

No ESC .............................................................................................................................................................. 186 ............... 330 

ESC .................................................................................................................................................................... 110 ............... 278 

Percent reduction in fatal single vehicle crashes in passenger cars with ESC ................................................ 30% .............. ........................

Approximate 95 percent confidence bounds ..................................................................................................... 10% to 50% ........................

Chi-square value ................................................................................................................................................ 6.0 ................ ........................

SUVs: 

No ESC .............................................................................................................................................................. 129 ............... 199 

ESC .................................................................................................................................................................... 25 ................. 103 

Percent reduction in fatal single vehicle crashes in SUVs with ESC ................................................................ 63% .............. ........................

Approximate 95 percent confidence bounds ..................................................................................................... 44% to 81% ........................

Chi-square value ................................................................................................................................................ 16.1 .............. ........................

(b) NHTSA’s Updated Study 

NHTSA has now updated and 

modified last year’s report, extending it 

to model year 1997–2004 vehicles—and 

to calendar year 2004 for the FARS 

analysis and calendar year 2003 for the 

State data analysis. Nevertheless, even 

as of 2004, a large proportion of the 

vehicles equipped with ESC were still 

luxury vehicles. Moreover, only 

passenger cars and SUVs had been 

equipped with ESC—no pickup trucks 

or minivans. 

The state databases included crash 

cases from California (2001–2003), 

Florida (1997–2003), Illinois (1997–

2002), Kentucky (1997–2002), Missouri 

(1997–2003), Pennsylvania (1997–2001, 

2003), and Wisconsin (1997–2003). The 

FARS database included fatal crash 

involvements from calendar years 1997 

to 2004. The extra year of exposure and 

the availability of data from more states 

significantly increased the sample size 

of crashes of vehicles with ESC. In the 

preliminary study, the state crash 

database contained 699 single-vehicle 

crashes of cars with ESC and 95 singlevehicle crashes of SUVs with ESC. The 

FARS database contained 110 singlevehicle crashes of cars with ESC and 25 

single-vehicle crashes of SUVs with 

ESC. For the updated study, the state 

crash database contains 2,251 singlevehicle crashes of cars with ESC and 

553 single-vehicle crashes of SUVs with 

ESC, and the FARS database of fatal 

single-vehicle crashes contains 157 and 

47 crashes respectively, for passenger 

cars and SUVs with ESC. 

The larger sample of crashes in the 

updated study facilitated a new analysis 

of the effectiveness of ESC on specific 

subsets of single-vehicle crashes (SV 

run-off-road crashes and SV crashes 

resulting in rollover). It also facilitated 

the use of a more focused control group 

of crashes that were unlikely to be 

affected by ESC so that a new analysis 

of the effect of ESC on multi-vehicle 

crashes could be undertaken. 

The basic analytical approach was to 

estimate the reduction of crash 

involvements of the types that are most 

likely to have benefited from ESC—

relative to a control group of other types 

of crashes where ESC is unlikely to have 

made a difference in the vehicle’s 

involvement. Crash types taken as the 

new control group (non-relevant 

involvements because ESC would in 

almost all cases not have prevented the 

crash) were crash involvements in 

which a vehicle: 

(1) Was stopped, parked, backing up, 

or entering/leaving a parking space prior 

to the crash, 

(2) Traveled at a speed less than 10 

mph, 

(3) Was struck in the rear by another 

vehicle, or 

(4) Was a non-culpable party in a 

multi-vehicle crash on a dry road. 

The types of crash involvements 

where ESC would likely or at least 

possibly have an effect are: 


jlentini on PROD1PC65 with PROPOSAL2
Federal Register / Vol. 71, No. 180 / Monday, September 18, 2006 / Proposed Rules 54721 

(1) All single vehicle crashes, except 

those with pedestrians, bicycles, or 

animals (SV crashes). 

(2) Single vehicles crashes in which a 

vehicle ran off the road (SV ROR) and 

hit a fixed object and/or rolled over. 

(3) Single vehicles crashes in which a 

vehicle rolled over (SV Rollover), 

mostly a subset of SV ROR. 

(4) Involvements as a culpable party 

in a multi-vehicle crash on a dry or wet 

road (MV Culpable). 

(5) Collisions with pedestrians, 

bicycles, or animals (Ped, Bike, Animal). 

In the updated study we performed 

the state data analysis separately for 

each state. Then we used the median of 

the estimates from the seven states as 

the best indicator of the central 

tendency of the data, and the variation 

of the seven states as a basis for judging 

statistical significance and estimating 

confidence bounds. The results of this 

analysis are presented in Table 3. 

TABLE 3.—UPDATED STUDY—MEAN EFFECTIVENESS OF ESC IN REDUCING CRASHES IN PASSENGER CARS AND SUVS

BASED ON SEPARATE ANALYSES OF 1997–2003 CRASH DATA FROM SEVEN STATES

SV crashes SV ROR SV rollover MV culpable Ped, bike, animal 

Passenger Cars: 

Mean percent reduction of listed crash 

type in passenger cars with ESC.

34% ........... 46% ........... 71% ........... 11% ........... 34% 

Approximate 90 percent confidence 

bounds.

20% to 46% 35% to 55% 60% to 78% 4% to 18% 5% to 55%. 

SUVs: 

Mean percent reduction of listed crash 

type in SUVs with ESC.

59% ........... 75% ........... 84% ........... 16% ........... ¥4% not statistically significant. 

Approximate 90 percent confidence 

bounds.

47% to 68% 68% to 80% 75% to 90% 7% to 24% ¥28% to 15%. 

Fatal crashes were analyzed 

separately using the FARS database as 

was done in the preliminary study, but 

larger sample sizes were possible 

because of an additional year of data. 

The results are given in Table 4. 

TABLE 4.—UPDATED STUDY-EFFECTIVENESS OF ESC IN REDUCING FATAL CRASHES OF PASSENGER CARS AND SUVS

BASED ON 1997–2004 FARS DATA

SV crashes SV ROR SV rollover MV culpable Ped, bike, animal Control group 

Passenger Cars: 

No ESC ................ 223 ................. 217 ................. 36 ................... 176 ............................. 46 ............................... 166 

ESC ...................... 157 ................. 154 ................. 12 ................... 156 ............................. 69 ............................... 181 

Percent reduction 

of listed crash 

type in passenger cars with 

ESC.

35% ................ 36% ................ 69% ................ 19% not statistically 

significant.

¥38% not statistically 

significant.

..........................

Approximate 90 

percent confidence bounds.

20% to 51% ... 19% to 51% ... 52% to 87% ... ¥2% to 39% .............. ¥87% to 12% ............ ..........................

Chi-square value .. 8.58 ................ 8.17 ................ 12.45 .............. 1.82 ............................ 2.14 ............................ ..........................

SUVs: 

No ESC ................ 197 ................. 191 ................. 106 ................. 108 ............................. 56 ............................... 153 

ESC ...................... 47 ................... 38 ................... 9 ..................... 48 ............................... 40 ............................... 109 

Percent reduction 

of listed crash 

type in SUVs 

with ESC.

67% ................ 72% ................ 88% ................ 38% ............................ 0% not statistically significant...........................

Approximate 90 

percent confidence bounds.

55% to 78% ... 62% to 82% ... 81% to 95% ... 16% to 60% ................ ¥40% to 40% ............ ..........................

Chi-square ............ 29.57 .............. 36.44 .............. 42.4 ................ 4.89 ............................ 0.00 ............................ ..........................

The effectiveness of ESC in reducing 

fatal single-vehicle crashes is similar to 

the effectiveness in reducing singlevehicle crashes from state data that 

included mostly non-fatal crashes. In 

the case of fatal crashes as well, the 

effectiveness of ESC in reducing singlevehicle rollover crashes was particularly 

high. The effectiveness of ESC in 

reducing fatal culpable multi-vehicle 

crashes of SUVs was also higher than in 

the analysis of state data, and the 

parallel analysis of multi-vehicle 

crashes of passenger cars did not 

achieve statistical significance. 

The updated study of ESC 

effectiveness yielded robust results. The 

analysis of state data and a separate 

analysis of fatal crashes both reached 

similar conclusions on ESC 

effectiveness. ESC reduced single 

vehicle crashes of passenger cars by 34 

percent and single vehicle crashes of 

SUVs by 59 percent. The separate 

analysis of only fatal crashes supported 

the analysis of state data that included 

mostly non-fatal crashes. Therefore, the 

overall crash reductions demonstrated a 

significant life-saving potential for this 

technology. The effectiveness of ESC in 

reducing SV crashes shown in the latest 

data (Tables 3–4) is similar to the results 

of the preliminary analysis. 


jlentini on PROD1PC65 with PROPOSAL2
54722 Federal Register / Vol. 71, No. 180 / Monday, September 18, 2006 / Proposed Rules 

16A closed-loop algorithm is a cycle of operations 

followed by a computer that includes automatic 

adjustments based on the result of previous 

operations or other changing conditions. 

The effectiveness of ESC tended to be 

at least as great and possibly even 

greater for more severe crashes. 

Furthermore, the effectiveness of ESC in 

reducing the most severe type of crash 

in the study, the single-vehicle rollover 

crash, was remarkable. ESC reduced 

single-vehicle rollover crashes of 

passenger cars by 71 percent and of 

SUVs by 84 percent. This high level of 

effectiveness also carried over to fatal 

single-vehicle rollover crashes. 

The benefits presented in Section VII 

were calculated on the basis of the 

single-vehicle crash and single-vehicle 

rollover crash effectiveness results of 

Table 3 for reductions in non-fatal 

crashes and of Table 4 for reductions in 

fatal crashes. The single-vehicle rollover 

crash effectiveness results were applied 

only to first harmful event rollovers 

with the lower single-vehicle crash 

effectiveness results applied to all other 

rollover crashes for a more conservative 

benefit estimate. 

V. Agency Proposal 

As discussed in detail in section VII, 

NHTSA’s crash data study leads to the 

conclusion that an ESC requirement for 

light vehicles would save 1,536 to 2,211 

lives annually once all light vehicles 

have ESC. The level of life saving 

associated with ESC would be second 

only to seatbelts among the items of 

equipment or elements of design 

regulated by the Federal motor vehicle 

safety standards. It is further estimated 

that an ESC requirement would prevent 

between 50,594 and 69,630 MAIS 1–5 

injuries annually. The life saving 

benefits of ESC are considered very cost 

effective with a cost per equivalent 

fatality of $0.19 million under the most 

favorable assumptions and $0.43 

million under the least favorable 

assumptions. 

In order to capture these significant 

safety benefits NHTSA is proposing to 

establish FMVSS No. 126, Electronic 

Stability Control Systems, which would 

require passenger cars, light trucks and 

buses that have a GVWR under 4,536 Kg 

(10,000 lbs) GVWR to be equipped with 

an ESC system with a yaw stability 

control function equal to that of vehicles 

in current production. The benefits 

demonstrated by NHTSA’s crash data 

studies and sought by the proposed 

safety standard are the result of yaw 

stability control greatly reducing singlevehicle crashes and reducing some 

multi-vehicle crashes as well. None of 

the study vehicles was equipped with a 

roll stability control system. Thus, we 

are proposing equipment requirements 

that are met by every ESC-equipped 

vehicle in current production and 

performance requirements that we 

believe are met by about 98 percent of 

ESC-equipped vehicles in current 

production and will require nothing 

more than slight retuning of the other 

two percent. 

We are not proposing a roll stability 

control system because there are no data 

currently available to determine the 

effect of roll stability control on crashes. 

However, vehicle manufacturers may 

supplement the proposed ESC systems 

with roll stability control. 

As proposed, FMVSS No. 126 would 

incorporate both an equipment 

requirement and a performance 

requirement. Specifically, we are 

proposing an equipment requirement for 

ESC that would define the necessary 

elements of a yaw stability control 

system capable of effective oversteer 

and understeer interventions. The ESC 

equipment requirement is augmented by 

a performance test of the system’s 

oversteer intervention. We believe that 

an equipment requirement is necessary 

because establishing performance tests 

that would ensure that the ESC system 

operates under all road conditions and 

phases of driving is impractical. The 

number of tests would be immense, and 

many tests (particularly those using 

slippery surfaces) would not be 

repeatable enough for an objective 

regulation. A test requirement for 

understeer mitigation is particularly 

problematic because the understeer 

mitigation for many light trucks is 

programmed to occur only on slippery 

surfaces to avoid potential roll 

instability. 

The proposed standard includes a 

performance test of oversteer 

intervention conducted with a single 

highly repeatable maneuver performed 

on dry pavement over a range of steering 

angles with an automated steering 

machine. It is designed to ensure that 

the performance of the system is 

comparable to current production 

systems under a limited set of 

conditions that are optimal for 

repeatable testing, and it proves that the 

ESC system is programmed to perform 

its most basic task under ideal 

conditions. 

Most vehicles without ESC will spin 

out in this maneuver; so, a vehicle that 

avoids spin-out according to our 

objective yaw rate decay definition 

demonstrates that it has an ESC system 

typical of 2006 production vehicles. 

However, the maneuver is not so 

extreme that every vehicle without ESC 

will actually spin out. A few non-ESC 

vehicles will pass this particular 

maneuver test, however they would 

certainly spin out on slippery surfaces. 

Therefore, the test without the 

definition does not assure the safety 

benefits of ESC. 

All model year 2006 vehicles with 

ESC systems would satisfy the 

definitional requirements of the 

standard. Of the sixty-two ESC vehicles 

tested by NHTSA or the Alliance of 

Automobile Manufacturers (Alliance), 

whose test fleet supplemented 

NHTSA’s, only one would need minor 

reprogramming to pass the performance 

test. 

Some of the older vehicles in 

NHTSA’s crash data study would not 

pass the proposed requirements (e.g., 

among the early ESC systems, there 

were some that were not capable of 

understeer intervention). Nevertheless, 

over 85 percent of the data in NHTSA’s 

study represent vehicles (1998–2003 

model years) that we believe would 

satisfy the proposed requirements of the 

new safety standard. The study vehicles 

that did not satisfy the proposed 

standard had systems that were 

beneficial but less effective than the 

average. 

A. Definition of ESC 

The Society of Automotive Engineers 

(SAE) Surface Vehicle Information 

Report on Automotive Stability 

Enhancement Systems J2564 Rev 

JUN2004 provides an industry 

consensus definition of an ESC system. 

The definition in paragraph 4.6 of SAE 

J2564 specifies that a ESC system: 

(a) Is computer controlled and the 

computer contains a closed-loop algorithm 16

designed to limit understeer and oversteer of 

the vehicle. 

(b) Has a means to determine vehicle yaw 

velocity and sideslip. 

(c) Has a means to monitor driver steering 

input. 

(d) Has a means of applying and adjusting 

the vehicle brakes to induce correcting yaw 

torques to the vehicle. 

(e) Is operational over the full speed range 

of the vehicle (except below a low-speed 

threshold where loss of control is unlikely). 

We believe the SAE definition is a 

good basis for the proposed equipment 

requirement but that it requires minor 

clarifications to adequately describe 

current production systems. The 

definition that NHTSA proposes 

contains changes in paragraphs (a) and 

(b). Paragraph (a) has been changed to 

read: ‘‘(a) is computer controlled with 

the computer using a closed-loop 

algorithm to limit vehicle oversteer and 

to limit vehicle understeer when 

appropriate.’’


jlentini on PROD1PC65 with PROPOSAL2
Federal Register / Vol. 71, No. 180 / Monday, September 18, 2006 / Proposed Rules 54723 

17Forkenbrock, G. et al. (2005) Development of 

Criteria for Electronic Stability Control Performance 

Evaluation, DOT HS 809 974. 

18Forkenbrock et al (2005) NHTSA’s Light 

Vehicle Handling and ESC Effectiveness Research 

Program, 19th International Technical Conference 

on the Enhanced Safety of Vehicles (ESV), 

Washington, DC. 

This change recognizes that while all 

current ESC systems constantly limit 

oversteer, many of the systems used on 

vehicles with a high center of gravity 

only limit understeer on slippery 

surfaces where there is no danger that 

the understeer intervention could 

increase the possibility of tip-up. We 

also changed the expression about the 

‘‘computer containing the algorithm’’ to 

refer to the ‘‘computer using the 

algorithm’’ to reduce ambiguity. 

Furthermore, we note that ‘‘limiting’’

understeer and oversteer means keeping 

those conditions within bounds that 

allow ordinary drivers to maintain 

control of the vehicle in critical 

situations. It does not mean reducing 

understeer and oversteer to zero under 

all circumstances because that is an 

impossibility, certainly not 

representative of production ESC 

systems. 

Paragraph (b) has been changed to 

read: ‘‘(b) has a means to determine the 

vehicle’s yaw rate and to estimate its 

side slip. A distinction has been made 

between the ways yaw rate and side slip 

are obtained.’’ Current ESC systems use 

sensors to measure yaw rate, 

constituting an actual determination of 

this crucial metric, but they estimate 

rather than measure side slip. 

Also, the term ‘‘yaw velocity’’ has 

been changed to ‘‘yaw rate’’ because that 

is the term used in our research reports. 

Both terms have the same meaning. 

The SAE document also defines four 

categories of ESC systems: Two wheel 

and four wheel systems, each with or 

without engine control. The minimum 

system capable of understeer and 

oversteer intervention is the four-wheel 

system without engine control. SAE 

describes systems in this category as 

having the following attributes: 

(a) The system must have means to 

apply all four brakes individually and a 

control algorithm, which utilizes this 

capability. 

(b) The system must be operational 

during all phases of driving including 

acceleration, coasting, and deceleration 

(including braking). 

(c) The system must stay operational 

when ABS or Traction Control are 

activated. 

The proposed regulatory language 

would require an ESC system that 

combines the SAE definition with the 

minor clarifications discussed and the 

attributes of the four-wheel system 

without engine control. Nothing in the 

regulatory language conflicts with 

systems that employ engine control. 

In addition, the proposed regulatory 

language supplements the ESC 

equipment definition with a test of 

oversteer intervention which would 

define the minimum intensity of the 

oversteer intervention under certain test 

conditions. The test is performed with 

the vehicle coasting on a dry pavement 

with a high coefficient of friction. The 

test conditions are very narrow in 

comparison with the operational 

conditions specified in the equipment 

definition, but they are necessary to 

produce a practical test with the high 

level of repeatability. The performance 

test specifies a severe steering regime 

that would produce oversteer loss of 

control in nearly every vehicle without 

a modern ESC system, and it specifies 

a maximum time for the vehicle to cease 

its yaw motion after the steering returns 

to straight ahead. 

At this time, we cannot propose a 

similar test of the intensity of the ESC 

system’s understeer intervention. 

Typically, systems on vehicles with 

high centers of gravity do not perform 

understeer intervention on dry surfaces 

because that could increase the 

possibility of an on-road untripped 

rollover. In such case, attempting to 

maintain the driver’s desired path 

would increase lateral acceleration and 

roll moment. In fact, roll stability 

control works by inducing high levels of 

understeer when required to prevent 

tip-up. Therefore, tests of understeer 

intervention must be performed on low 

coefficient surfaces to avoid prohibiting 

roll stability control systems. 

Unfortunately, the regular methods of 

producing wet, slippery, or icy 

conditions at automotive proving 

grounds are useful only for such 

purposes as back-to-back comparisons 

of vehicles because repeatable friction 

conditions cannot be maintained or 

precisely reproduced. A practical test of 

understeer intervention is a topic of 

ongoing research. 

B. Performance Test of ESC Oversteer 

Intervention and Stability Criteria 

Selection of Maneuver 

NHTSA performed research to define 

a practical, repeatable and realistic 

maneuver test of ESC oversteer 

intervention. We also made use of the 

results of testing performed by the 

Alliance on some candidate maneuvers 

to supplement the agency’s information. 

NHTSA’s detailed research report 17 has 

been placed in the docket, and this 

section represents a summary of its 

major points. 

The desired test should discriminate 

strongly between vehicles with and 

without ESC. Vehicles with ESC 

disabled were used as non-ESC vehicles 

in the research. It must also facilitate the 

evaluation of both the lateral stability of 

the vehicle (prevention of spinout) and 

its responsiveness in avoiding obstacles 

on the road, since stability can be 

gained at the expense of responsiveness. 

The research program consisted of two 

phases: 

Phase 1: The evaluation of many 

maneuvers capable of quantifying the 

performance of ESC oversteer 

intervention using a small sample of 

diverse test vehicles. 

Phase 2: Evaluation of many vehicles 

using a reduced suite of candidate 

maneuvers. 

Phase 1 testing occurred during the 

period of April through October 2004. In 

this effort, twelve maneuvers were 

evaluated using five test vehicles. 

Maneuvers utilized automated and 

driver-based steering inputs. If driverbased steering was required, multiple 

drivers were used to assess input 

variability. To quantify the effects of 

ESC, each vehicle was evaluated with 

ESC enabled and disabled. Dry and wet 

surfaces were utilized; however, the wet 

surfaces introduced an undesirable 

combination of test variability and 

sensor malfunctions. Table 5 

summarizes the Phase 1 test matrix. 

Additional details pertaining to Phase 1, 

including more detailed maneuver 

descriptions and details pertaining to 

test conduct, have been previously 

documented.18


jlentini on PROD1PC65 with PROPOSAL2
54724 Federal Register / Vol. 71, No. 180 / Monday, September 18, 2006 / Proposed Rules 

19 Ibid. 

20Forkenbrock, G. et al. (2005) Development of 

Criteria for Electronic Stability Control Performance 

Evaluation, Dot HS 809 974. 

21 Docketed at NHTSA–2004–19951, item 1. 

TABLE 5.—NHTSA’S 2004 LIGHT VEHICLE HANDLING/ESC TEST MATRIX

Test group 1 Test group 2 Test group 3 

• Slowly Increasing Steer .................................. ........................................................................... • Closing Radius Turn. 

• NHTSA J-Turn (Dry, Wet) .............................. • Modified ISO 3888–22 .................................. • Pulse Steer (500 deg/s, 700 deg/s). 

• NHTSA Fishhook (Dry, Wet) .......................... • Constant Radius Turn .................................. • Sine Steer (0.5 Hz, 0.6 Hz, 0.7 Hz, 0.8 Hz). 

• Increasing Amplitude Sine Steer (0.5 Hz, 

0.6 Hz, 0.7 Hz. 

• Sine with Dwell (0.5 Hz, 0.7 Hz). 

• Yaw Acceleration Steering Reversal (YASR) 

(500 deg/s, 720 deg/s). 

• Increasing Amplitude YASR (500 deg/s, 720 

deg/s). 

To determine whether a particular test 

maneuver was capable of providing a 

good assessment of ESC performance, 

NHTSA considered the extent to which 

it possessed three attributes: 

1. A high level of severity that would 

exercise the oversteer intervention of 

every vehicle’s ESC system. 

2. A high level of repeatability and 

reproducibility. 

3. The ability to assess both lateral 

stability and responsiveness. 

Phase 2 testing examined the four 

maneuvers that were considered most 

promising from Phase 1: (1) Sine with 

Dwell; (2) Increasing Amplitude Sine 

Steer; (3)Yaw Acceleration Steering 

Reversal (YASR); and (4) YASR with 

Pause.19 The two yaw acceleration 

steering reversal maneuvers were 

designed to overcome the possibility 

that fixed-frequency steering maneuvers 

would discriminate on the basis of 

vehicle properties other than ESC 

performance, such as wheelbase length. 

They were more complex than the other 

maneuvers, requiring the automated 

steering machines to trigger on yaw 

acceleration peaks. However, Phase 2 

research revealed an absence of effects 

of yaw natural frequency. Therefore, the 

YASR maneuvers were dropped from 

further consideration because their 

increased complexity was not warranted 

in light of equally effective but simpler 

alternatives, and their details will not be 

discussed in this summary of NHTSA 

research. Additional detail on the 

remaining maneuvers is presented 

below: 

Sine With Dwell 

As shown in Figure 2, the Sine with 

Dwell maneuver was based on a single 

cycle of sinusoidal steering input. 

Although the peak magnitudes of the 

first and second half-cycles were 

identical, the Sine with Dwell maneuver 

included a 500 ms pause after 

completion of the third quarter-cycle of 

the sinusoid. In Phase 1, frequencies of 

0.5 and 0.7 Hz were used. In Phase 2, 

only 0.7 Hz Sine with Dwell maneuvers 

were performed. As described in 

NHTSA’s report,20 the 0.7 Hz frequency 

was found to be consistently more 

severe than its 0.5 Hz counterpart (in 

the context of this research, severity was 

quantified by the amount of steering 

wheel angle required to produce a 

spinout). In Phase 1, the 0.7 Hz Sine 

with Dwell was able to produce 

spinouts with lower steering wheel 

angles for four of the five vehicles 

evaluated, albeit by a small margin (no 

more than 20 degrees of steering wheel 

angle for any vehicle). 

In a presentation 21 given to NHTSA 

on December 3, 2004, the Alliance also 

reported that the 0.5 Hz Sine with Dwell 

did not correlate as well with the 

responsiveness versus controllability 

ratings made by its professional test 

drivers in a subjective evaluation (the 

same vehicles evaluated with the Sine 

with Dwell maneuvers were also driven 

by the test drivers), and it provided less 

input energy than the 0.7 Hz Sine with 

Dwell. 

Increasing Amplitude Sine 

As shown in Figure 3, the Increasing 

Amplitude Sine maneuver was also 

based on a single cycle of sinusoidal 

steering input. However, the amplitude 

of the second half-cycle was 1.3 times 

greater than the first half-cycle for this 

maneuver. In Phase 1, frequencies of 

0.5, 0.6, and 0.7 Hz were used for the 

first half cycle; the duration of the 

second half cycle was 1.3 times that of 

the first. 

The Phase 1 vehicles were generally 

indifferent to the frequency associated 

with the Increasing Amplitude Sine 

maneuver. Given our desire to reduce 

the test matrix down from three 

maneuvers based on three frequencies to 

one, NHTSA selected just the 0.7 Hz 

frequency Increasing Amplitude Sine 

for use in Phase 2. In the previously 

mentioned presentation given to 

NHTSA on December 3, 2004, the 

Alliance also reported that the 0.6 Hz 

Increasing Amplitude Sine did not 

induce vehicle responses significantly 

different than the 0.5 and 0.7 Hz 

Increasing Amplitude Sine maneuvers. 

To select the best overall maneuver 

from those used in Phase 2, NHTSA 

considered three attributes: (1) 

Maneuver severity, (2) face validity, and 

(2) performability. Of the two sinusoidal 

maneuvers used in Phase 2, we 

determined that the Sine with Dwell 

was the best candidate for evaluating 

the lateral stability component of ESC 

effectiveness because of its relatively 

greater severity. Specifically, it required 

a smaller steering angle to produce 

spinouts (for test vehicles with ESC 

disabled). Also, the Increasing 

Amplitude Sine maneuver produced the 

lowest yaw rate peak magnitudes in 

proportion to the amount of steering, 

implying the maneuver was the least 

severe for most vehicles evaluated by 

NHTSA in Phase 2. 

The performability of the Sine with 

Dwell and Increasing Amplitude Sine 

maneuvers is excellent. The maneuvers 

are very easy to program into the 

steering machine, and their lack of rate 

or acceleration feedback loops 

simplifies the instrumentation required 

to perform the tests. As mentioned 

previously, Phase 2 testing revealed that 

the extra complexity of YASR 

maneuvers was unnecessary because the 

tests were not affected by yaw natural 

frequency differences between vehicles. 

All Phase 2 maneuvers (including the 

YASR maneuvers) possess an inherently 

high face validity because they are each 

comprised of steering inputs similar to 

those capable of being produced by a 

human driver in an emergency obstacle 

avoidance maneuver. However, the 

Increasing Amplitude Sine maneuver 

may possess the best face validity. 

Conceptually, the steering profile of this 

maneuver is the most similar to that 

expected to be used by real drivers, and 

even with steering wheel angles as large 


jlentini on PROD1PC65 with PROPOSAL2
Federal Register / Vol. 71, No. 180 / Monday, September 18, 2006 / Proposed Rules 54725 

as 300 degrees, the maneuver’s 

maximum effective steering rate is a 

very reasonable 650 deg/sec. 

In light of the above, NHTSA is 

proposing to use the Sine with Dwell 

maneuver to evaluate the performance 

of light vehicle ESC systems in 

preventing spinout (oversteer loss of 

control). On the balance we believe that 

it offers excellent face validity and 

performability, and its greater severity 

makes it a more rigorous test while 

maintaining steering rates within the 

capabilities of human drivers. 

Spinout Criteria 

The foregoing maneuver selection 

process required a definition of 

‘‘spinout.’’ Spinout can be best 

explained in the context of the Sine 

with Dwell maneuver. Figure 4 shows 

the steering wheel angle driven by a 

robotic steering machine during three 

runs of the maneuver at increasing 

steering amplitudes and the resulting 

measurements of the yaw rate of an 

actual vehicle being tested. The 

maneuver is the same as that shown in 

Figure 2, except that the first steering is 

to the left in Figure 4 while it is to the 

right in Figure 2. 

The test protocol requires the test to 

be performed at an entrance speed of 50 

mph (coasting) in both directions at 

increasing steering amplitudes up to a 

preset maximum or to the point at 

which the vehicle spins out (failing the 

test). The preset maximum steering 

angle is the larger of either 270 degrees 

or an angle equal to 6.5 times the 

steering angle that produces 0.3g steady 

state lateral acceleration for the 

particular test vehicle. This 

specification of maximum test steering 

angle takes into account differences in 

steering gear ratio, wheelbase, and other 

factors between vehicles, but provides 

for testing to a steering wheel angle of 

at least 270 degrees. This maximum 

steering wheel angle is not achieved in 

the event that the test is terminated by 

spinout at a lower steering wheel angle. 

As shown in Figure 4, in the first run, 

the steering wheel is turned 80 degrees 

to the left, then 80 degrees to the right 

following a smooth 0.7 Hz sinusoidal 

pattern. It is held steady for a dwell time 

of 0.5 second at 80 degrees right, and 

then returned to zero (straight ahead) 

also following a sinusoidal pattern. 

After a short lag, the vehicle begins to 

yaw counter-clockwise in response to 

the left steering. The absolute value of 

the yaw velocity increases with the 

absolute value of the steering angle, and 

then the vehicle changes to clockwise 

yaw velocity in response to right 

steering. At two seconds after the 

beginning of steering, the steering wheel 

has been turned back to straight ahead, 

and the yaw rate returns to zero after a 

fraction of a second response time. At 

that point, the vehicle is being steered 

straight ahead, and it is going straight 

ahead without any yaw rotation. The 

vehicle is responding closely to the 

steering input, and the driver is in 

control. 

When the steering amplitude is 

increased to 120 degrees in the next run, 

the vehicle achieves greater yaw 

velocity because it is following a tighter 

path at the same speed, but it exhibits 

the same good response to steering and 

remains in control. 

However, when the steering 

amplitude is increased to 169 degrees, 

the vehicle spins out, exhibiting 

oversteer loss of control. This condition 

is identified in the yaw rate trace. When 

the steering is straight ahead at time = 

2 seconds, the yaw rate for this run is 

still about 35 deg/sec. However, there is 

a time lag past the instant of steering to 

straight ahead even for the previous 

runs where there was no loss of control. 

What is different is that the yaw rate 

does not swiftly decline to zero as it 

does with a vehicle under control. At 

time = 3 seconds, the yaw rate is still 

the same, and it has actually increased 

at time = 4 seconds in this example. The 

physical interpretation of this graph is 

that the driver has turned the wheels 

straight ahead and wants the vehicle to 

go straight, but the vehicle is spinning 

clockwise about a vertical axis through 

its center of gravity. It is out of control 

in a spinout. The driver’s steering input 

is not causing the vehicle to take the 

desired path and heading, and the 

vehicle would depart the road surface 

sideways or even backward. 

Figure 4 illustrates that the Sine with 

Dwell Maneuver is very severe. It 

induced a dramatic spinout in this test 

vehicle with only 169 degrees of 

steering to one direction followed by 

169 degrees to the other. It is possible 

that steering angles below 169 degrees 

but above 120 degrees would also have 

caused spinout. Since the test is 

predicated on steering angles up to (or 

possibly exceeding) 270 degrees, it 

would cause spinout in vehicles with 

far greater lateral stability than this test 

vehicle. 

Figure 5 shows another series of tests 

of the same vehicle but with ESC 

enabled. The first two runs were at 80 

and 120 degrees of steering angle, and 

the vehicle’s yaw rate declined to zero 

in a fraction of a second after the 

steering command. This is the same 

good response to steering exhibited by 

the vehicle with ESC disabled in the 

previous figure. The third run was 

conducted at 180 degrees of steering 

angle. This is greater than the 169 

degrees that caused a severe loss of 

control without ESC, but the yaw rate 

returned to zero with the steering angle 

just as quickly as in the runs with less 

steering. 

The final set of curves in Figure 5 

represent a run conducted with 279 

degrees of steering angle. This would be 

the left-right portion of the performance 

test proposed for the ESC system of this 

vehicle since 279 degrees is 6.5 times 

the steering angle that produces 0.3g 

steady state lateral acceleration for this 

example vehicle. In this case, the yaw 

rate did not return to zero nearly 

instantaneously as it had at lower 

steering angle. Instead, it steadily 

declined after the steering was turned to 

straight ahead, and the vehicle was 

completely stable and going straight in 

about 1.75 seconds. Clearly, the vehicle 

remained in control compared to its 

behavior without ESC (see Figure 4) in 

which turning the steering to straight 

ahead had no effect on the vehicle’s 

heading. However, the ESC system 

required some time to cause the vehicle 

to stop turning in response to the 

driver’s straight ahead steering 

command because the preceding 

maneuver was so destabilizing. The 

time it takes for the vehicle to stop 

rotating after it is steered straight ahead 

in this maneuver is a measure of the 

aggressiveness of the ESC oversteer 

intervention. Some of the early ESC 

systems were tuned to be less aggressive 

than the example vehicle, and the lag 

time for the vehicle to ‘‘recover’’ from 

the Sine with Dwell Maneuver would be 

longer. 

The first goal of an ESC system is to 

prevent spinout, but there is no hard 

quantitative definition of spinout. 

Obviously, the example in Figure 4 

shows spinout. The vehicle turned 

nearly front to rear in four seconds with 

the steering wheel straight ahead. In the 

example of Figure 5, the vehicle always 

responded to steering, but some 

response time was required for it to 

fully stabilize. In seeking to define 

‘‘spinout’’, the agency believes that the 

question is: How long must the response 

time be before the result would be 

considered a spinout in the severe test 

maneuver? 

NHTSA used an empirical definition 

of spinout based on observations from 

vehicle maneuver testing as a rule of 

thumb. This empirically-based criterion 

stipulates that in a symmetric steer 

maneuver, in which the amount of right 

and left steering is equal, if the final 

heading angle is more than 90 degrees 

from the initial heading, the vehicle has 

spun out. If a symmetric steer maneuver 

is performed at a very low speed that 


jlentini on PROD1PC65 with PROPOSAL2
54726 Federal Register / Vol. 71, No. 180 / Monday, September 18, 2006 / Proposed Rules 

22Forkenbrock, g. et al. (2005) Development of 

Criteria for Electronic Stability Control Performance 

Evaluation, DOT HS 809 974 

eliminates tire slippage, the heading 

does not change at all. However, a 

change of heading of about 20 degrees 

would occur even at low speed in the 

Sine with Dwell Maneuver because of 

the asymmetric dwell portion, making 

this empirical criterion more 

conservative. NHTSA’s research 

report 22 contains a statistical study on 

how quickly an ESC system would have 

to respond to prevent a heading change 

of more than 90 degrees during the Sine 

with Dwell Maneuver at 50 mph with 

full steering using data from all 40 

vehicles tested by NHTSA and the 

Alliance. 

Two measures of response time were 

considered: (1) The remaining yaw rate 

(as a percent of peak) one second after 

the steering wheel was turned straight 

ahead, and (2) the remaining percent of 

peak yaw rate after 1.75 seconds. The 

peak yaw rate is the highest yaw rate 

during the second part of the maneuver. 

In the example of Figure 5 (test run with 

279 degrees steering wheel angle) the 

steering returned to straight ahead at 2 

seconds. At 3 seconds (one second 

later), the remaining yaw rate was about 

30 percent of the peak value achieved at 

about 1.2 seconds. At 3.75 seconds (1.75 

seconds after zero steer), the remaining 

yaw rate is zero percent. Statistical 

analyses performed by NHTSA predict 

that, if the remaining yaw rate at one 

second after zero steer was no more than 

35 percent, there is a 95 percent (or 

greater) probability that the heading 

change will not exceed 90 degrees (no 

spinout by the empirical criterion). For 

the 1.75 second time interval, a 

remaining yaw rate of no more than 20 

percent leads to the same prediction. 

The heading change criterion and its 

statistical interpretation provide a 

context in which to view the yaw rate 

data in the Sine with Dwell tests 

conducted by NHTSA and by the 

Alliance on a large sample of 62 

vehicles in production in 2005. Figure 

6 illustrates the yaw rate response (as a 

percent of the second yaw rate peak) 

versus time after completion of steer 

(COS) input, for the 0.7 Hz Sine with 

Dwell maneuver (left to right steering) 

for all vehicles tested by NHTSA and 

the Alliance. The data represents the 

most severe yaw rate response produced 

for each vehicle during a particular test 

series. The form of the graph 

corresponds to the yaw rate curve (for 

the 169 degree test) shown in Figure 4, 

except that the yaw rate has been 

normalized and the time axis has been 

shifted by 2.0 seconds so as to focus on 

the yaw rate response after COS. The 

cluster of curves at the top of Figure 6 

represents the yaw rate response for 

vehicles with the ESC totally disabled, 

and the cluster at the bottom are for 

vehicles with the ESC fully enabled. 

Figure 7 shows data from the same 

vehicles but in a test conducted with 

right-left steering rather than left-right 

as in Figure 6. 

Figures 6 and 7 also show the 

proposed criteria for maximum yaw rate 

at 1.0 second and 1.75 seconds after 

completion of steering. All of the 62 

current production vehicles tested met 

or exceeded the proposed criteria with 

ESC enabled when tested in the leftright sequence as shown in Figure 6. 

However, one of the vehicles did not 

meet the criteria when tested in the 

right-left sequence as shown in Figure 7. 

Nevertheless, we believe the proposed 

criteria reasonably represent the 

minimum performance of the oversteer 

intervention for present vehicles with 

ESC, and that the vehicle representing 

the single exception to the rule can be 

tuned to operate as well in the right-left 

steering as it did in the left-right test. 

NHTSA also tested a number of the 

older vehicles whose crash data were 

used to evaluate the effectiveness of ESC 

in crash reduction. We believe that over 

85 percent of these vehicles have ESC 

systems that would pass the proposed 

criteria. Therefore, the following 

proposed performance criteria for the 

Sine with Dwell Maneuver test of ESC 

oversteer intervention is associated with 

the high level of crash prevention 

benefits we expect and is also typical of 

the minimum performance of the 

present fleet of ESC vehicles: 

In both criteria, 

C. Responsiveness Criteria 

NHTSA’s track tests demonstrate 

dramatic improvements in yaw stability 

provided by ESC. However, NHTSA 

believes these improvements should not 

come at the expense of poor lateral 

displacement response to the driver’s 

steering inputs. An extreme example of 

this potential lack of responsiveness 

would occur if an ESC system locked 

both front wheels as the driver begins an 

abrupt obstacle avoidance maneuver. 

Assuming the road is reasonably level, 

and the surface friction is uniform, it is 

very likely the wheel lock would 

suppress any tendency for the vehicle to 

spin out or tip up. However, having the 

wheels lock would also prevent the 


jlentini on PROD1PC65 with PROPOSAL2EP18SE06.000</MATH> EP18SE06.001</MATH>
Federal Register / Vol. 71, No. 180 / Monday, September 18, 2006 / Proposed Rules 54727 

23 Docketed at NHTSA–2004–19951, item 21. 

vehicle from responding to the driver’s 

steering inputs. This would cause the 

vehicle to plow straight ahead and 

collide with the obstacle the driver was 

trying to avoid. Clearly this is not a 

desirable compromise. 

To ensure an acceptable balance 

between lateral stability and the ability 

for the vehicle to respond to the driver’s 

inputs, NHTSA believes a 

‘‘responsiveness’’ criterion must 

supplement the agency’s lateral stability 

criteria. We propose to use the same 

series of tests with the Sine with Dwell 

maneuver to characterize both the 

aggressiveness of the oversteer 

intervention and the lateral 

responsiveness of the vehicle. This 

maneuver is severe enough to exercise 

the ESC system on any vehicle and test 

its oversteer intervention, and it is 

possible to measure other metrics 

during the Sine with Dwell maneuver to 

characterize the vehicle’s 

responsiveness as well. 

NHTSA considered a number of 

metrics to describe the ability of the 

vehicle to react to the steering input, 

especially in the direction of the first 

half sine of the steering pattern that 

would relate most directly to obstacle 

avoidance. These metrics involved the 

lateral movement of the vehicle, the 

lateral speed of the vehicle, the lateral 

acceleration of the vehicle and lag times 

and distances between steering inputs 

and the various types of responses. 

The lateral movement of the vehicle 

has the most obvious and direct bearing 

on obstacle avoidance. However, the 

measurement of lateral movement 

appeared to introduce an undesirable 

degree of difficulty. NHTSA has been 

measuring the path of vehicles during 

the development of various rollover and 

handling test maneuvers using a 

differentially corrected Global 

Positioning System (GPS) method. This 

method is capable of measuring the 

lateral movement of the vehicle at its 

center of gravity (a good way to compare 

vehicles of different sizes), but it 

requires costly instruments both on the 

track and in the vehicle and complex 

procedures. Instruments imbedded in 

the track would seem to be a possible 

alternative, but they are also 

problematic. It is difficult to place each 

test vehicle over the instrumented 

section of roadway during the exact 

same position in the Sine with Dwell 

steering pattern, and it is difficult to 

determine the lateral movement of the 

center of gravity from roadway sensors 

when the vehicles approach at various 

side slip angles. 

However, during a briefing 23 on 

September 7, 2005, the Alliance 

presented a technique that would 

greatly simplify the measurement of 

NHTSA’s preferred responsiveness 

metric—lateral displacement in the 

direction of the first steering of the Sine 

with Dwell maneuver. It involves 

mathematical integration of the onboard 

lateral acceleration measurement at the 

vehicle center of gravity to obtain lateral 

velocity, and then a second integration 

of lateral velocity to obtain lateral 

displacement. Double integration of 

acceleration to calculate displacement is 

not used as a general measurement 

technique because small errors in zero 

levels of acceleration and speed can 

produce large errors in displacement 

over time. However, the idea presented 

by the Alliance required double 

integration for only about one second, 

and the resulting displacement 

calculations were in good agreement 

with the GPS measurements for vehicles 

tested by NHTSA. 

Figure 8 shows the typical lateral 

displacement as a function of time for 

a vehicle performing the Sine with 

Dwell maneuver successfully (without 

spinning out). Since the longitudinal 

travel is roughly proportional to time, 

the bottom trace resembles the path of 

the vehicle with the lateral travel 

exaggerated. Assuming the wheel is first 

turned to the left, the figure shows that 

the maximum movement of the vehicle 

to the left lags the maximum left 

steering angle by almost two seconds in 

this example. Because this maneuver 

includes a very fast steering reversal, the 

steering wheel has been turned sharply 

to the right before the vehicle has 

achieved its maximum reaction to the 

initial left steering. 

We propose to use the lateral 

displacement at 1.07 seconds after 

initiation of steering in the Sine with 

Dwell maneuver as the responsiveness 

metric rather than the maximum lateral 

displacement for the following reasons. 

The maximum lateral displacement 

occurs later in the maneuver and occurs 

at different times for different vehicles. 

Therefore, it is subject to greater 

potential error from the double 

integration technique, and the errors 

could systematically affect some types 

of vehicles more than others. 

More importantly, since the 

interpretation of the metric is the 

obstacle avoidance capability of the 

vehicle, it makes the most sense to 

measure the lateral displacement of 

every vehicle the same distance from 

the initiation of steering. This is 

equivalent to placing the same size 

obstruction at the same place on the 

roadway for every vehicle. Since 

steering is initiated at 50 mph for all 

tests, and not much speed is scrubbed 

off in the first second (except for a few 

systems that start automatic braking 

very early in the maneuver), lateral 

displacement at a set time is roughly 

equivalent to lateral displacement at a 

set distance. Certainly, the difference in 

distance traveled among test vehicles is 

much less at 1.07 seconds into the 

maneuver than at the point of maximum 

lateral displacement. 

A set time of 1.07 seconds is desirable 

because it coincides with an easily 

recognized discontinuity in the steering 

trace (the dwell period); it is short 

enough to assure accuracy of the double 

integration technique, and it is long 

enough to include a high percent of the 

maximum lateral displacement. It is also 

important to note that differences 

between vehicles in the lateral 

displacement metric at 1.07 seconds 

correlated well with the subjective 

evaluations of vehicle responsiveness 

provided by expert drivers from several 

vehicle manufacturers. 

The choice of the criterion for this 

metric was based on the responsiveness 

of the present fleet of cars and light 

trucks, represented by a group of 61 

vehicles in 107 vehicle configurations 

(ESC on or ESC off). The group ranged 

from high-performance sports cars to a 

15-passenger van with ESC and several 

long wheelbase diesel pickup trucks 

with GVWRs near 4,536 Kg (10,000 lb) 

and no ESC. Figure 9 shows the range 

of responsiveness for this fleet, 

characterized by the proposed metric. 

The least responsive vehicles were not 

the 15-passenger van or large pickup 

trucks, but rather SUVs with roll 

stability control. The highest criterion 

that can be used without prohibiting 

these implementations of roll stability 

control is a minimum lateral 

displacement of 1.83 m (half a 12-foot 

lane width), 1.07 seconds after initiation 

of steering in the Sine with Dwell 

maneuver conducted with steering 

angles of 180 degrees or greater. 

Therefore, we are proposing the test 

criterion for minimum vehicle 

responsiveness described above because 

it is practical for all types of light 

vehicles including 15-passenger vans, 

long wheelbase diesel pickups and 

SUVs with roll stability control. All of 

the test vehicles would satisfy this 

criterion, including nine SUVs with a 

roll stability control function. However, 

we expect that manufacturers would 

make some software alterations to the 

roll stability control programs of a few 

SUVs to gain a greater margin of 

compliance. 


jlentini on PROD1PC65 with PROPOSAL2
54728 Federal Register / Vol. 71, No. 180 / Monday, September 18, 2006 / Proposed Rules 

D. Other Issues 

1. ESC Off Switches 

Many vehicles are equipped with ESC 

systems featuring driver-selectable 

modes. These modes are generally 

subdivided into two groups: (1) Systems 

in which the driver has the ability to 

fully disable the ESC (i.e., throttle and 

brake intervention are both eliminated), 

and (2) those in which the ESC may 

only be partially disabled. If the option 

to fully disable the ESC exists, the 

manner in which it is accomplished 

depends largely on the vehicle’s make 

and model. For some vehicles, disabling 

the ESC is accomplished by 

momentarily pushing an on/off button 

typically located on the instrument 

panel, center console, or dashboard. 

Other vehicles require the driver to 

push the ESC on/off button for 

approximately three to five seconds 

before the ESC can be fully disabled. 

Regardless of which method the 

vehicle manufacturer has selected, the 

action to manually disable ESC requires 

a conscious effort by the driver. The 

default setting of every ESC system 

known to NHTSA is ‘‘ESC-enabled.’’ In 

other words, at the beginning of each 

ignition cycle, the ESC is always fully 

enabled regardless of what mode the 

driver had been operating the vehicle in 

during the previous ignition cycle. 

Although many contemporary 

vehicles are equipped with ESC on/off 

switches, simply pushing the ESC on/off 

button does not necessarily give the 

driver the ability to fully disable the 

vehicle’s ESC. For some vehicles, when 

the drivers select ‘‘ESC off,’’ they are 

actually diminishing, but not fully 

removing, the aggressiveness of their 

vehicles’ ESC intervention. 

Although the crash and test track data 

clearly demonstrate the profound safety 

benefits of ESC, there are special 

circumstances in which drivers may 

wish to partially or fully disable their 

vehicles’ ESC. Examples of such 

situations may include: 

• Attempting to ‘‘rock’’ a vehicle 

stuck in a deformable surface such as 

snow or mud 

• Attempting to initiate movement on 

deep snow or ice (especially if the 

vehicle is equipped with snow chains) 

• Driving through a deep, deformable 

surface such as mud or sand 

• Driving with a compact spare tire, 

tires of mismatched sizes or tires with 

chains. 

To understand how ESC may hinder 

a driver’s ability to operate his vehicle 

in these special conditions, it is 

important to recall the primary ways in 

which ESC attempts to improve 

stability: (1) Removal or augmentation 

of drive torque, and (2) brake 

intervention. In each of the examples 

provided above, the vehicle may require 

significant longitudinal wheel slip in 

order to initiate or maintain forward 

progress. If ESC remains fully enabled, 

it will endeavor to reduce what it 

perceives as excessive wheel slip via 

throttle and/or brake intervention. By 

reducing wheel slip, the vehicle’s lateral 

stability is improved; however, this may 

also inhibit forward progress to the 

point that the vehicle may become (or 

remain) stuck. Not only can this be 

frustrating for the driver (i.e., the 

vehicle is not responding to their 

commands), but it may also introduce a 

potential safety problem (e.g., the 

vehicle slows to a near stop while 

attempting to be driven through a busy 

intersection). 

Another reason a driver may wish to 

disable ESC has less to do with 

mobility, and more to do with driving 

enjoyment. NHTSA acknowledges there 

is a driver demographic that considers 

the automobile more than just a means 

of transportation. These drivers enjoy 

participation in activities such as 

motorsports competition and highperformance driving schools. In these 

situations, it is quite possible the driver 

may not wish to realize the improved 

lateral stability offered by a fully 

enabled ESC, because the intervention 

providing improved lateral stability is 

achieved by removing the driver’s 

throttle inputs and applying the brakes. 

In a controlled environment, such as the 

confines of a racetrack, this can be 

frustrating for the driver because ESC 

intervention will have the effect of 

slowing the vehicle and contradict the 

driver’s desire to achieve the lowest 

possible lap times. In other words, 

aggressive intervention intended to 

improve safety on the public roads may 

not be appropriate at a racetrack. 

To accommodate these special 

situations, NHTSA believes vehicle 

manufacturers should be allowed the 

freedom to install ESC on/off switches 

on all vehicles. Furthermore, the agency 

is hopeful that this provision will have 

a positive effect on ESC design 

philosophy. For every ESC system 

presently in production, there exists a 

balance between lateral stability and 

intervention magnitude. Generally 

speaking, an ESC tuned to optimize 

lateral stability will require intrusive 

interventions. Conversely, a vehicle 

equipped with an ESC designed with 

transparent intervention which is not 

noticeable to the driver (often associated 

with ‘‘sport’’ modes), will tend to 

exhibit lower lateral stability. By giving 

vehicle manufacturers the freedom to 

install ESC on/off switches, both 

intervention strategies can be 

accommodated, with the more 

aggressive safety-biased tuning set as the 

system default. The more sport-oriented, 

transparent interventions could then be 

accessed via the same switch capable of 

fully disabling the ESC. This provision 

should satisfy the demand for safe, 

versatile, and enjoyable vehicles. 

Vehicle and ESC manufacturers have 

expressed concern that if ESC on/off 

switches were to be prohibited, there 

would exist a risk that some drivers will 

fully disable their vehicle’s ESC by 

other means, such as disconnecting or 

removing sensors required by the ESC. 

By opting to disable ESC in this manner, 

drivers might unknowingly disable 

other important safety features such as 

the vehicle’s antilock brakes. In some 

cases, the vehicle’s electronic brake 

proportioning may also be adversely 

affected, thereby resulting in a 

significant reduction of the vehicle’s 

braking capability. Recognizing the 

diverse operating conditions their 

vehicles may encounter, many vehicle 

manufacturers presently equip their 

vehicles with ESC on/off switches. 

In light of the above, we are proposing 

to permit installation of ESC Off 

switches as a manufacturer option. 

However, in order to preserve the safety 

benefits presently associated with ESC, 

NHTSA is proposing to require a vehicle 

equipped with an ESC on/off switch to 

satisfy three important criteria: 

1. The vehicle’s ESC must always be 

fully enabled at the initiation of each 

new ignition cycle, regardless of what 

mode the driver had previously 

specified. 

2. When evaluated with its ESC fully 

enabled, the vehicle performance must 

be in compliance with the minimum 

ESC oversteer intervention and 

responsiveness test criteria. 

3. The vehicle manufacturer must 

provide a telltale light that illuminates 

to indicate when the vehicle has been 

put into a mode that completely 

disables ESC or renders it unable to 

satisfy the ESC oversteer intervention 

test criteria. 

In summary, although there is no way 

to guarantee drivers will not use ESC 

on/off switches to disable their vehicle’s 

ESC during normal driving, potentially 

negating the significant safety benefits 

such systems offer, NHTSA cannot 

ignore the fact there are certain 

operating conditions under which on/ 

off switches are advantageous. 

Furthermore, NHTSA anticipates that 

ESC developers will utilize this design 

flexibility facilitated by the use of ESC 

on/off switches to maximize the ESC 

effectiveness in its default, fully enabled 

mode. 


jlentini on PROD1PC65 with PROPOSAL2
Federal Register / Vol. 71, No. 180 / Monday, September 18, 2006 / Proposed Rules 54729 

24Mazzae, E. et al. (2005) The effectiveness of 

ESC and related Telltales: NADS Wet Pavement 

Study, DOT HS 809 978. 

25Papelis et al. (2004) Study of ESC Assisted 

Driver Performance Using a Driving Simulator, 

Report No. N)4–003–PR, University of Iowa. 

2. ESC Activation and Malfunction 

Symbols and Telltale 

Most current ESC systems provide an 

indication to the driver when the ESC 

system is actively intervening to 

stabilize the vehicle and provide a 

warning to the driver if ESC is 

unavailable due to a failure in the 

system. When an ESC Off switch is 

provided, a telltale reminds the driver 

when the ESC has been disabled. 

We believe that there are safety 

benefits associated with certain of these 

warnings. There is an obvious safety 

need to warn the driver in case of an 

ESC malfunction so that the system can 

be repaired. The safety need to remind 

the driver of a driver-selected ESC Off 

state is also obvious because the driver 

should restore the ESC function as soon 

as possible in order to realize the 

system’s safety benefits. However, the 

safety need for an ESC activation 

indicator to alert the driver during an 

emergency situation that ESC is 

intervening is not obvious, so the 

agency undertook research on this point 

as discussed below. 

NHTSA conducted a study 24 using 

the National Advanced Driving 

Simulator (NADS) that included 

experiments to gain insight into the 

various possibilities regarding ESC 

activation indicators. The NHTSA study 

involved 200 participants in four age 

groups and simulated driving on wet 

pavement. It used maneuvers similar to 

those described in Section IV of the 

Papelis study 25 also using the NADS. 

The activation indicator experiments 

used road departures and eye glances to 

the instrument panel as measures of 

driver performance. The NHTSA study 

compared the performance of drivers 

given either no indication of ESC 

activation, a steady-burning icon 

telltale, a flashing icon telltale, or an 

auditory warning. The ESC telltale used 

in this study was the ISO J.14 symbol 

with the text ‘‘Active’’ under it. 

Participants presented with only 

auditory ESC activation indications 

experienced significantly more road 

departures (15) than participants 

receiving visual only indications (steady 

8, flashing 8) or no ESC activation 

indications (7). This finding was most 

evident for the older driver group who 

experienced a statistically significant 

increase in road departure events with 

the auditory ESC indication compared 

to the other three conditions. Younger 

drivers also showed an increased road 

departure rate with the auditory ESC 

indication, although not at a statistically 

significant level. These results of the 

road departure study are presented in 

Table 6. 

TABLE 6.—PERCENT ROAD DEPARTURES BY ESC ACTIVATION INDICATION AND AGE GROUP—ESC TRIALS ONLY

All age 

groups 

combined 

(percent) 

Novice 

(percent) 

Younger 

(percent) 

Middle 

(percent) 

Older 

(percent) 

None ........................................................................................................ 7 8 8 6 6 

Steady ...................................................................................................... 8 10 4 6 10 

Flashing ................................................................................................... 8 9 6 9 8 

Auditory .................................................................................................... 15 6 14 10 30 

Eye glance behavior was examined to 

determine whether providing drivers 

with an indication of ESC activation 

would cause them to glance at the 

instrument panel. Results show that 

participants presented with a flashing 

ESC telltale glanced at the instrument 

panel significantly more frequently (14, 

statistically significant) during the 

crash-imminent event than did 

participants in the other three ESC 

conditions. Participants presented with 

a flashing ESC telltale also glanced at 

the instrument panel approximately 

twice during the crash-imminent event 

versus once for participants in the other 

three ESC conditions. However, average 

glance duration was approximately 

twice as long for the auditory ESC 

indication condition than for the other 

three ESC conditions (see Table 7), 

although this difference was not 

statistically significant. 

TABLE 7.—EFFECT OF ESC ACTIVATION INDICATION ON EYE GLANCE BEHAVIOR—ESC TRIALS ONLY

Percent trials 

with any 

glance to 

icon 

Number of glances per trial Duration of glances(s) 

M SD M SD 

None ...................................................................................................... 28 1.4 3.9 0.3 0.9 

Steady .................................................................................................... 27 1.1 2.6 0.2 0.1 

Flashing ................................................................................................. 41 2.3 4.7 0.3 0.8 

Auditory .................................................................................................. 27 1 2.6 0.6 1.6 

Overall, the significant finding was 

that the drivers who received various 

ESC activation indicators did not 

perform better than drivers given no 

indicator. Therefore, there does not 

appear to be a safety need to propose a 

requirement for an ESC activation 

indicator as part of this rulemaking, and 

none is proposed. In fact, presentation 

of an auditory indication of ESC 

activation was shown to increase the 

likelihood of road departure, 

particularly for older drivers. As a 

result, use of an auditory indication of 

ESC activation presented during the 

ESC activation is not recommended. 

The flashing indicator was associated 

with a greater number of glances to the 

instrument panel during the critical 

driving maneuvers. Therefore, flashing 

would not seem to be a desirable 

feature, but there was no measurable 

consequence in road departures. The 

current practice for many vehicles is to 


jlentini on PROD1PC65 with PROPOSAL2
54730 Federal Register / Vol. 71, No. 180 / Monday, September 18, 2006 / Proposed Rules 

use the same ESC telltale for both 

activation and malfunction. It flashes to 

indicate activation and stays on 

continuously in a steady burning mode 

to indicate ESC malfunction. Since 

NHTSA is proposing to not regulate the 

activation mode, the current practice 

need not be affected. 

The threshold of ESC intervention 

that would trigger an indication of 

activation is likely to vary with the 

philosophy of the manufacturer. Some 

manufacturers would also favor 

displaying the activation signal to the 

driver shortly after the critical driving 

maneuver has ended. This idea may be 

more intuitively appealing because the 

driver would be warned of slippery road 

conditions while avoiding potential 

distraction during the critical maneuver. 

This rulemaking does not propose 

regulation in this area. 

NHTSA believes that the symbol used 

to identify ESC malfunction (and 

activation if the telltale is shared) 

should be standardized. This is not the 

case for presently available systems. 

There are three main types of identifiers 

for ESC activation and malfunction. One 

type of icon shows the rear of a vehicle 

trailed by a pair of ‘‘S’’ shaped skid 

marks. This is the ISO ESC symbol 

(designated J.14 in ISO standard 2575). 

We observed seven variations of this 

icon in production vehicles. The second 

type is based on a triangle surrounding 

an exclamation mark, which is also used 

to indicate ABS and traction control 

activation on some vehicles. A variation 

of this type adds an outer 

counterclockwise semicircular arrow to 

indicate rotation. The third type 

includes English language phrases and 

acronyms often referring to trade names 

for specific ESC systems. 

To the extent possible, NHTSA favors 

symbols over English abbreviations to 

promote harmonization. Also, acronyms 

for different trade names for ESC would 

only serve to confuse drivers who 

operate different vehicles produced by 

different manufacturers. 

NHTSA collected data on the 

recognition of various identifiers related 

to ESC and other vehicle systems by 

administration of an icon 

comprehension test. A total of 20 

members of the general public 

participated in this data collection 

effort. Gender was balanced. Each 

participant was first presented with an 

instructional sheet describing the 

procedure for the icon test. The 

instructions included the following 

statement: ‘‘You are driving down the 

road and this image illuminates on your 

vehicle’s instrument panel * * * ’’. 

Participants were then given the test, 

which consisted of a hand-sized packet 

containing the 20 icons, each on a 

different page. Each page contained two 

separate questions to ensure that 

responses were sufficiently detailed. 

The questions were: ‘‘What system or 

part of the car is the light referring to?’’

and ‘‘What is the light telling you about 

that part or system?’’ A fill-in-the-blank 

line for participant response followed 

each question. 

Responses for ESC-related symbols 

were given full credit as correct if they 

contained the words ‘‘stability control’’

or ‘‘ESC.’’ ESC icon responses 

containing the word ‘‘traction’’ were 

given partial credit. Selected results of 

the comprehension test are presented in 

Figure 10. While few people knew what 

‘‘ESC’’ meant, the ISO J.14 icon was the 

most successful in communicating to 

people a message relating to traction. 

The icon consisting of a 

counterclockwise, circular arrow 

surrounding a triangle containing an 

exclamation point, while present in a 

number of current vehicles, was not 

meaningful to any of the 20 

respondents, and there was little 

recognition of the triangle without the 

arrow. 

Based upon the results of this albeit 

limited study, the ISO J.14 symbol 

appears to be the best choice of the 

identifiers in use for a standard symbol 

for ESC. As with any symbol, drivers 

will have to learn its precise meaning, 

but we believe that, to some extent, it 

correctly evokes an association with 

skidding. Also, the ISO J.14 symbol and 

close variations were the symbols used 

presently by the greatest number of 

vehicle manufacturers that used an ESC 

symbol. Therefore, NHTSA is proposing 

the ISO J.14 symbol as the required ESC 

symbol in FMVSS No. 126. 

3. ESC Off Switch Symbol and Telltale 

There is an obvious safety need to 

prevent drivers from misunderstanding 

the operation of the ESC Off switch. 

Drivers usually encounter vehicle 

dashboard switches as a means of 

turning on vehicle functions that are off 

when the vehicle is started. However, an 

ESC Off switch presents the opposite 

situation, because full ESC operation is 

the default condition of the vehicle 

following each ignition cycle. Therefore, 

we believe that the switch must be 

labeled unambiguously. 

The ISO convention is to draw a slash 

through a symbol to signify negation—

the disabling or turning off of a vehicle 

function. However, Table 8, which 

examines potential symbols to indicate 

when the ESC system is off, shows that 

this convention applied to the ISO J.14 

ESC symbol does not create an 

unambiguous symbol for ESC off. 

Once again, the ISO J.14 symbol is 

desirable because it connoted the idea of 

traction and skidding even to people 

who had not heard of electronic stability 

control. However, the literal meaning of 

the symbol of a vehicle skidding with a 

slash through it is the negation of 

skidding, which could be assumed to 

mean ESC on. The problem with the 

slash symbol is not just that a driver 

will not understand it and have to 

consult the owner’s manual, but that the 

driver could reasonably understand it to 

have the opposite meaning and believe 

it is not necessary to consult the owner’s 

manual. Therefore, a purely 

pictographic approach to adapting the 

ESC symbol for the off switch is not 

feasible. NHTSA believes it is necessary 

to make the identification of when ESC 

is turned off explicit by using the 

English word ‘‘OFF,’’ as shown in the 

right hand box of Table 8. 

The same situation occurs for the 

telltale indicating what the current state 

of ESC system is. The off switch toggles 

the ESC system between the on and off 

states. Even someone who understands 

that the ESC Off switch is not required 

to use ESC normally must be certain of 

the ESC state after he has touched the 

switch. Therefore, the slash symbol 

cannot be used for the telltale either 

because it leads to the same ambiguity 

regarding the state of the ESC system 


jlentini on PROD1PC65 with PROPOSAL2EP18SE06.002</GPH>
Federal Register / Vol. 71, No. 180 / Monday, September 18, 2006 / Proposed Rules 54731 

26Pub. L. 109–59, 119 stat. 1144 (2005). 

27 57 FR 242 (Jan. 3, 1992). 

28 Dang, J. (2006) Statistical Analysis of The 

Effectiveness of Electronic Stability Control (ESC) 

Systems, U.S. Dept. of Transportation, Washington, 

DC (publication pending peer review). A draft 

version of this report, as supplied to peer reviewers, 

has been placed in the docket for this rulemaking. 

when the telltale is lighted. Also, even 

though it is used for malfunction 

indication, the ISO J.14 symbol alone 

would create ambiguity about the on/off 

state of ESC if it were used with the Off 

switch. Therefore, the symbol with the 

English word ‘‘OFF’’ is also proposed 

for the telltale that will be required for 

the ESC Off switch. 

E. Alternatives to the Agency Proposal 

Section 10301 of the Safe, 

Accountable, Flexible, Efficient 

Transportation Equity Act: A Legacy for 

Users of 2005 26 (SAFETEA–LU) 

requires that the Secretary ‘‘establish 

performance criteria to reduce the 

occurrence of rollovers consistent with 

stability enhancing technologies’’ and 

‘‘issue a proposed rule * * * by October 

1, 2006, and a final rule by April 1, 

2009.’’ NHTSA has long been concerned 

about the number of rollover fatalities 

and injuries, and it has pursued a 

number of actions in the past to reduce 

rollovers that were alternatives to the 

present proposal. 

One of the past alternatives sought to 

require higher rollover resistance for 

light trucks. NHTSA published an 

Advance Notice of Proposed 

Rulemaking in 1992 27 which explored 

the idea of setting a minimum level of 

rollover resistance based on the track 

width and height of the center of 

gravity. These are the primary 

components of ‘‘geometric stability’’

which can be expressed by metrics such 

as Static Stability Factor (SSF) or Tilt 

Table Ratio which is a related 

measurement using a ‘‘tilt table’’ to 

measure how far a vehicle on a platform 

could be tilted laterally before tipping 

over. 

However, the contemplated approach 

of regulating the geometric stability of 

vehicles did not lead to a mandatory 

standard. Its effect would have been 

crash mitigation by reducing the 

number of single-vehicle crashes that 

turn into rollovers rather than crash 

prevention. In order to produce life 

saving benefits, the proposed geometric 

stability level would have had to be 

placed above that of almost all 

contemporary SUVs, pickup trucks with 

four-wheel drive, and full size vans. A 

regulation of this type would have made 

classes of vehicles with high ground 

clearance unavailable to consumers. 

Rather than pursue such a 

rulemaking, NHTSA chose instead to 

add rollover resistance to the NCAP 

consumer information program in 2001. 

In this way, persons needing vehicles 

with high ground clearance (which have 

poorer rollover resistance) could make 

an informed choice about the tradeoffs, 

but consumers would be encouraged to 

choose vehicles with greater rollover 

resistance. The NCAP program uses 

market-based incentives to encourage 

manufacturers to maximize rollover 

resistance within the limitations of the 

vehicle class. Manufacturers responded 

to these NCAP ratings with 

improvements in rollover resistance 

resulting from the generally wider track 

widths of newer SUVs derived from 

passenger car platforms and also 

improvements where possible in truckbased SUVs during major redesigns. A 

recent trend in improving the rollover 

resistance of SUVs has been the 

addition of roll stability control. This 

feature prevents tip-up in the maneuver 

test that was added to NCAP in the 2004 

model year, resulting in a small 

reduction in the predicted rollover rate. 

We believe the NCAP approach has 

been a successful way to address the 

dilemma of higher rollover resistance 

being at odds with some of the features 

that draw consumers to light trucks. 

Despite the recent trend of 

improvement, SUVs cannot match 

passenger cars in geometric stability 

because taller bodies and higher ground 

clearance are the features that 

distinguish SUVs from passenger cars. 

Nevertheless, the rollover resistance of 

SUVs has substantially improved since 

the establishment of NCAP ratings, and 

consumers are in a better position to 

make vehicle decisions for themselves 

and for young drivers in their family. 

While the use of ESC to prevent single 

vehicle crashes is a better way of 

reducing rollovers than any 

countermeasures previously available, 

there are alternatives in terms of how 

NHTSA could regulate ESC systems. 

The agency considered two alternatives 

to the proposal. The first was to limit 

the ESC standard’s applicability only to 

LTVs. The second alternative was to not 

require a 4-wheel system, which would 

allow a 2-wheel system to be used by 

manufacturers. 

The agency considered the first 

alternative for two reasons: (a) The ESC 

effectiveness rates for LTVs against 

single-vehicle crashes were almost twice 

as high of the effectiveness rates for 

passenger cars (PCs), and (b) LTVs 

generally had a higher propensity for 

rollover than PCs. The alternative would 

address the core rollover issue and 

target the high-risk rollover vehicle 

population. However, after examining 

the safety impact and the costeffectiveness of the alternative, the 

agency determined that an excellent 

opportunity to reduce passenger car 

crashes would be lost if PCs were 

excluded from the proposal. 

We examined this alternative by 

looking at the impacts of requiring ESC 

for passenger cars. Requiring ESC for 

passenger cars would save 956 lives and 

reduce 34,902 non-fatal injuries. 

Following this analysis through the 

cost-effectiveness equations, the costeffectiveness analysis shows that ESC is 

highly cost-effective for PCs alone. For 

PCs, the cost per equivalent life saved 

is estimated to be $0.35 million at a 3 

percent discount rate and $0.47 million 

at a 7 percent discount rate. The benefitcost would be $4.8 billion at a 3 percent 

discount rate and $3.8 billion at a 7 

percent discount rate. 

Given the fact that ESC is highly costeffective and that extending the ESC 

applicability to PCs would save a large 

number of additional lives (956) and 

reduce a large number of additional 

injuries (34,902), the agency is not 

proposing this alternative. 

The second alternative considered 

was to require only that ESC operate on 

the two front wheels. General Motors 

has utilized a 2-wheel ESC system in 

many of its ESC-equipped passenger 

cars through MY 2005, but it is using 4- 

wheel ESC systems exclusively in MY 

2006. All other manufacturers have 

utilized a 4-wheel ESC system in their 

vehicles. Only 4-wheel systems are 

capable of both understeer and oversteer 

mitigation. 

Statistical analyses comparing 2- 

wheel to 4-wheel ESC systems were 

performed.28 The effectiveness 

estimates show a potentially enhanced 

benefit of 4-wheel ESC systems over 2- 

wheel ESC systems in reducing singlevehicle run-off-road crashes (significant 

at the 0.05 level or better), although the 

benefit could not have been shown in a 

separate analysis of fatal-only crashes 

likely due to the small sample size. 

The agency’s contractor performed a 

teardown study to determine the 

difference in costs between a 2-wheel 

and 4-wheel system, and it found that 

the 2-wheel system is about $10.00 less 

expensive. However, it is not intuitively 

obvious that the difference need be this 

much, and with a sample size of one, it 

is possible that other changes in design 

may be affecting this estimate. 

Since the industry has moved away 

from the 2-wheel system on its own, and 

it appears that the difference in cost of 

$10 or less will be insignificant 

compared to the additional benefits 


jlentini on PROD1PC65 with PROPOSAL2
54732 Federal Register / Vol. 71, No. 180 / Monday, September 18, 2006 / Proposed Rules 

achieved with 4-wheel ESC, we are not 

providing a full analysis of this 

alternative at this time. 

Based on the available information, 

the agency is proposing the 4-wheel 

system. The agency’s decision is based 

on our and the industry’s engineering 

judgment that the 4-wheel system is 

more effective, the effectiveness study 

showing that the 4-wheel system is 

more effective than the 2-wheel system 

in reducing crashes, the industry trend 

towards installing the 4-wheel system in 

their vehicles, and the minimal cost 

differences between 2-wheel and 4- 

wheel ESC systems. 

We have also examined the possibility 

that there may be alternative approaches 

to achieving the benefits of ESC that 

could involve simpler or less costly 

technology. To answer this question we 

first identified the basic functional 

requirements of a vehicle control system 

that would maintain vehicle path 

control in both oversteer and understeer 

situations. The first functional 

requirement is a means of predicting 

what the driver’s intended path, i.e., 

where the driver wants the vehicle to 

go. The second functional requirement 

is to be able to determine the current 

actual path of the vehicle, i.e., its 

current dynamic state. The final 

requirement is to determine how the 

intended and actual paths deviate and 

then to exercise automatic control to 

minimize or eliminate this deviation. 

The basic question then is whether there 

exists another fundamentally different 

technological approach to achieving the 

three key functional requirements 

identified above, than those employed 

in current ESC systems. 

Functional Requirement No. 1: One 

may infer the desired path from a 

knowledge of the driver’s instantaneous 

steering, throttle, and braking 

commands as well as the current 

dynamic state of the vehicle. This 

requires that sensors be installed to 

determine the values of each of these 

control inputs. Although specific sensor 

technology and costs may vary from one 

manufacturer to another, there is no 

known alternative to acquiring 

knowledge of the driver’s intent other 

than through this system of vehicle 

sensors. 

Functional Requirement No. 2: Once 

the intended path is established, the 

next requirement is determine the 

vehicle’s actual path. Here again a range 

of sensor information is needed to 

establish the vehicle’s dynamic state. 

Among the state variables that must be 

determined, the two most critical are 

lateral acceleration and yaw velocity. 

Acquiring information of these 

quantities requires special vehicle 

dynamic sensors. Again, though sensor 

technology and cost may vary, we are 

not aware of any alternative approach to 

acquiring this essential information. 

Functional Requirement No. 3: With 

information on the driver’s desired path 

and the actual vehicle path, a means of 

comparing the two and eliminating or 

minimizing deviations is needed. This 

requires an electronic comparator and 

error generator. A means of altering the 

actual vehicle path so as to bring it into 

alignment with the desired path is the 

third critical function. The vehicle path 

can only be changed as a result of forces 

generated between the tire and roadway. 

Drivers intuitively rely on lateral tire 

forces generated through steering inputs 

to change the vehicle heading and path. 

Though not comprehended by most 

drivers, the heading (and consequently 

the path) can also be changed by means 

of unbalanced braking forces, which is 

the approach used by ESC. We do not 

believe that an approach that would 

assume control of the driver’s steering 

authority as an alternative method of 

correcting the vehicle path would be 

acceptable to most drivers. Also, braking 

intervention at individual wheels is 

much more likely to produce the 

necessary yaw torque on slippery 

surfaces than steering intervention, and 

steering intervention would have 

limited effect on understeer loss-ofcontrol even on surfaces with high 

levels of friction. No manufacturer has 

proposed this method of intervention to 

correct path deviation in loss of control 

situations. 

In summary, while specific 

differences in the implementation may 

exist between ESC systems, the basic 

elements of the feed-back control 

systems are common to all. We have 

concluded that to accomplish the goal of 

preventing a vehicle from losing path or 

directional control a vehicle must be 

equipped with all of the essential 

components of the current ESC systems. 

There does not appear to be any current 

alternative to the technology that is 

being mandated that attains the goals of 

this proposed rule. We solicit comment 

on alternatives to mandating the 

installation of ESC, consistent with our 

statutory directive. 

VI. Leadtime 

Considering the very high level of 

potential life-saving benefits of this 

proposed safety standard, NHTSA 

wishes to avoid excessive delay in its 

development and implementation. 

Except for possibly some lowproduction-volume vehicles with 

infrequent design changes, NHTSA 

believes that most other vehicles can 

reasonably be equipped with ESC 

within three to four model years (MY) 

from the date of issuance of a final rule. 

This proposal does not require 

improvements in ESC technology over 

the present 2006 MY systems, and most 

vehicles would likely experience some 

level of redesign in the next five years 

in the normal course of business. There 

already is a strong trend to provide ESC 

as standard equipment on SUVs, and it 

is likely that market segment will be 

equipped with ESC prior to a final rule 

becoming effective. We have taken these 

considerations into account in 

proposing both the phase-in plan as 

well as the final compliance date for full 

implementation of the standard. 

Our intention is to have 90 percent of 

the subject fleet equipped with ESC in 

the 2011 model year that starts 

September 1, 2010. Accordingly, 

assuming the final rule is published in 

June 2008, and becomes effective 

September 1, 2008, we are proposing the 

following phase-in schedule: 

September 1, 2008—30 percent of fleet. 

September 1, 2009—60 percent of fleet. 

September 1, 2010—90 percent of fleet. 

September 1, 2011—All light vehicles. 

However, NHTSA is proposing to 

exclude multi-stage manufacturers and 

alterers from the requirements of the 

phase-in and to extend by one year the 

time for compliance by those 

manufacturers (i.e., until September 1, 

2012). This NPRM also proposes to 

exclude small volume manufacturers 

(i.e., manufacturers producing less than 

5,000 vehicles for sale in the U.S. 

market in one year) from the phase-in, 

instead requiring such manufacturers to 

fully comply with the standard on 

September 1, 2011. 

Under our proposal, vehicle 

manufacturers would be permitted to 

earn carry-forward credits for compliant 

vehicles, produced in excess of the 

phase-in requirements, which are 

manufactured between the effective date 

of the final rule and the conclusion of 

the phase-in period. We note that carryforward credits would not be permitted 

to be used to defer the mandatory 

compliance date of September 1, 2011 

for all covered vehicles. 

The initial phase-in of 30 percent 

occurring almost simultaneously with 

the effective date is the result of our 

belief that all manufacturers subject to 

the phase-in already plan to exceed that 

level of ESC installation in the 2009 

MY. Confidential information submitted 

to NHTSA by many manufacturers 

indicate that all responding 

manufacturers will exceed a 30 percent 

installation rate, and that several will 

exceed it by a large margin that would 

earn considerable carry-forward credits. 


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Federal Register / Vol. 71, No. 180 / Monday, September 18, 2006 / Proposed Rules 54733 

VII. Benefits and Costs 

A. Summary 

This section summarizes our analysis 

of the benefits, costs, and cost per 

equivalent life saved as a result of the 

proposed ESC requirement. As noted 

previously, the life- and injury-saving 

potential of ESC is very significant, both 

in absolute terms and when compared 

to prior agency rulemakings. This 

proposal for ESC, if made final, would 

save 1,536 to 2,211 lives and cause a 

reduction of 50,594 to 69,630 MAIS 1–

5 injuries annually once all passenger 

vehicles have ESC. This compares 

favorably with the Regulatory Impact 

Analyses for other important 

rulemakings such as FMVSS No. 208 

mandatory air bags (1,964 to 3,670 lives 

saved), FMVSS No. 214 side impact 

protection (690 to 1,030 lives saved), 

and FMVSS No. 201 upper interior head 

impact protection (870 to 1,050 lives 

saved). The ESC proposal would also 

save $396 to $555 million annually in 

property damage and travel delay 

(undiscounted). The total cost of the 

proposal is estimated to be $985 

million. 

The proposal is extremely costeffective. The cost per equivalent life 

saved would range from $0.19 to $0.32 

million at a 3 percent discount and 

$0.27 to $0.43 million at a 7 percent 

discount. Again, the cost-effectiveness 

for ESC compares favorably with the 

Regulatory Impact Analyses for other 

important rulemakings such as FMVSS 

No. 202 head restraints safety 

improvement ($2.61 million per life 

saved), FMVSS No. 208 center seat 

shoulder belts ($3.39 to $5.92 million 

per life saved), FMVSS No. 208 

advanced air bags ($1.9 to $9.0 million 

per life saved), and FMVSS No. 301 fuel 

system integrity upgrade ($1.96 to $5.13 

million per life saved). 

For a more complete discussion of the 

benefits and costs associated with this 

proposed rulemaking for ESC, please 

consult the Preliminary Regulatory 

Impact Analysis (PRIA), which is 

available in the docket for this 

rulemaking. 

B. ESC Benefits 

As discussed in detail in Chapter IV 

(Benefits) of the PRIA, we anticipate 

that this rulemaking would prevent 

70,344 to 95,153 crashes (1,408 to 2,355 

fatal crashes and 69,936 to 91,798 nonfatal crashes). Preventing these crashes 

entirely is the ideal safety outcome and 

would translate into 1,536 to 2,211 lives 

saved and 50,594 to 69,630 MAIS 1–5 

injuries prevented. 

The above figures include benefits 

related to rollover crashes. However, in 

light of the relatively severe nature of 

crashes involving rollover, ESC’s 

contribution toward mitigating the 

problem associated with this subset of 

crashes should be noted. We anticipate 

that this rulemaking would prevent 

37,309 to 41,147 rollover crashes (1,057 

to 1,314 fatal crashes and 36,252 to 

39,833 non-fatal crashes). This would 

translate into 1,161 to 1,445 lives saved 

and 43,901 to 49,010 MAIS 1–5 injuries 

prevented in rollovers. 

In addition, preventing crashes would 

also result in benefits in terms of travel 

delay savings and property damage 

savings. We estimate that this 

rulemaking would save $396 to $555 

million, undiscounted, in these two 

categories ($310 to $348 million of this 

savings attributable to prevented 

rollover crashes). 

C. ESC Costs 

In order to estimate the cost of the 

additional components required to 

equip every vehicle in future model 

years with an ESC system, assumptions 

were made about future production 

volume and the relationship between 

equipment found in anti-lock brake 

systems (ABS), traction control (TC), 

and ESC systems. We assumed that in 

an ESC system, the equipment of ABS 

is a prerequisite. Thus, if a passenger car 

did not have ABS, it would require the 

cost of an ABS system plus the 

additional incremental costs of the ESC 

system to comply with an ESC standard. 

We assumed that traction control (TC) 

was not required to achieve the safety 

benefits found with ESC. We estimated 

a future annual production of 17 million 

light vehicles consisting of nine million 

light trucks and eight million passenger 

cars. 

An estimate was made of the MY 2011 

installation rates of ABS and ESC. It 

served as the baseline against which 

both costs and benefits are measured. 

Thus, the cost of the standard is the 

incremental cost of going from the 

estimated MY 2011 installations to 100 

percent installation of ABS and ESC. 

The estimated MY 2011 installation 

rates are presented in Table 9. 

TABLE 9.—MY 2011 PREDICTED

INSTALLATIONS

[Percent of the light vehicle fleet] 

ABS ABS + ESC 

Passenger Cars 86 65 

Light Trucks ...... 99 77 

Based on the assumptions above and 

the data provided in Table 9, Table 10 

presents the percent of the MY 2011 

fleet that would need these specific 

technologies in order to equip 100 

percent of the fleet with ESC. 

TABLE 10.—PERCENT OF THE LIGHT VEHICLE FLEET REQUIRING TECHNOLOGY TO ACHIEVE 100% ESC INSTALLATION

None ABS + ESC ESC only 

Passenger Cars ....................................................................................................................................... 65 14 21 

Light Trucks ............................................................................................................................................. 77 1 22 

The cost estimates developed for this 

analysis were taken from tear down 

studies that contractors have performed 

for NHTSA. This process resulted in 

estimates of the consumer cost of ABS 

at $368 and the incremental cost of ESC 

at $111. Thus, it would cost a vehicle 

that does not have ABS currently, $479 

to meet this proposal. Combining the 

technology needs in Table 10 with the 

cost above and assumed production 

volumes yields the cost estimate in 

Table 11 for the proposed standard. 


jlentini on PROD1PC65 with PROPOSAL2
54734 Federal Register / Vol. 71, No. 180 / Monday, September 18, 2006 / Proposed Rules 

TABLE 11.—SUMMARY OF VEHICLE COSTS FOR THE ESC PROPOSAL

[2005$] 

Average 

vehicle costs 

Total costs 

(million) 

Passenger Cars ......................................................................................................................................................... $90 .3 $728 

Light Trucks ............................................................................................................................................................... 29 .2 363 

Total .................................................................................................................................................................... 58 985 

In summary, Table 11 shows that the 

new vehicle costs of providing 

electronic stability control and antilock 

brakes will add approximately $985 

million to new light vehicles at a cost 

averaging over $58 per vehicle. 

In addition, we note that this proposal 

would add weight to vehicles and 

consequently would increase their 

lifetime use of fuel. Most of the added 

weight is for ABS components and very 

little is for the ESC components. Since 

99 percent of light trucks are predicted 

to have ABS in MY 2011, the weight 

increase for light trucks is less than one 

pound and is considered negligible. The 

average weight gain for passenger cars is 

estimated to be 2.1 pounds, resulting in 

2.6 more gallons of fuel being used over 

the lifetime of these vehicles. The 

present discounted value of the added 

fuel cost over the lifetime of the average 

passenger car is estimated to be $2.73 at 

a 7 percent discount rate and $3.35 at 

a 3 percent discount rate. 

We have not included in these cost 

estimates, allowances for ESC system 

maintenance and repair. Although all 

complex electronic systems will 

experience component failures from 

time to time necessitating repair, our 

experience to date with existing systems 

is that their failure rate is not outside 

the norm. Also, there are no routine 

maintenance requirements for ESC 

systems. 

VIII. Public Participation 

How Can I Influence NHTSA’s Thinking 

on This Notice? 

In developing this notice, NHTSA 

tried to address the concerns of all 

stakeholders. Your comments will help 

us determine what standard should be 

set for ESC as part of FMVSS No. 126. 

We invite you to provide different views 

about the issues presented, new 

approaches and technologies about 

which we did not ask, new data, how 

this notice may affect you, or other 

relevant information. We welcome your 

views on all aspects of this notice. Your 

comments will be most effective if you 

follow the suggestions below: 

• Explain your views and reasoning 

as clearly as possible. 

• Provide empirical evidence, 

wherever possible, to support your 

views. 

• If you estimate potential costs, 

explain how you arrived at that 

estimate. 

• Provide specific examples to 

illustrate your concerns. 

• Offer specific alternatives. 

• Reference specific sections of the 

notice in your comments, such as the 

units or page numbers of the preamble, 

or the regulatory sections. 

• Be sure to include the name, date, 

and docket number of the proceeding as 

part of your comments. 

How Do I Prepare and Submit 

Comments? 

Your comments must be written and 

in English. To ensure that your 

comments are correctly filed in the 

Docket, please include the docket 

number of this document in your 

comments. 

Your comments must not be more 

than 15 pages long. (49 CFR 553.21). We 

established this limit to encourage you 

to write your primary comments in a 

concise fashion. However, you may 

attach necessary additional documents 

to your comments. There is no limit on 

the length of the attachments. 

Please submit two copies of your 

comments, including the attachments, 

to Docket Management at the address 

given above under ADDRESSES. 

You may also submit your comments 

to the docket electronically by logging 

onto the Dockets Management System 

Web site at http://dms.dot.gov. Click on 

‘‘Help & Information’’ or ‘‘Help/Info’’ to 

obtain instructions for filing your 

document electronically. 

How Can I Be Sure That My Comments 

Were Received? 

If you wish Docket Management to 

notify you upon its receipt of your 

comments, enclose a self-addressed, 

stamped postcard in the envelope 

containing your comments. Upon 

receiving your comments, Docket 

Management will return the postcard by 

mail. Each electronic filer will receive 

electronic confirmation that his or her 

submission has been received. 

How Do I Submit Confidential Business 

Information? 

If you wish to submit any information 

under a claim of confidentiality, you 

should submit three copies of your 

complete submission, including the 

information you claim to be confidential 

business information, to the Chief 

Counsel, NHTSA, at the address given 

above under FOR FURTHER INFORMATION

CONTACT. In addition, you should 

submit two copies, from which you 

have deleted the claimed confidential 

business information, to Docket 

Management at the address given above 

under ADDRESSES. When you send a 

comment containing information 

claimed to be confidential business 

information, you should include a cover 

letter delineating that information, as 

specified in our confidential business 

information regulation. (49 CFR part 

512.) 

Will the Agency Consider Late 

Comments? 

We will consider all comments that 

Docket Management receives before the 

close of business on the comment 

closing date indicated above under 

DATES. To the extent possible, we will 

also consider comments that Docket 

Management receives after that date. If 

Docket Management receives a comment 

too late for us to consider it in 

developing a final rule (assuming that 

one is issued), we will consider that 

comment as an informal suggestion for 

future rulemaking action. 

How Can I Read the Comments 

Submitted by Other People? 

You may read the comments received 

by Docket Management at the address 

given above under ADDRESSES. The 

hours of the Docket are indicated above 

in the same location. 

You may also review filed public 

comments on the Internet. To read the 

comments on the Internet, take the 

following steps: 

1. Go to the Docket Management 

System (DMS) Web page of the 

Department of Transportation (http:// 

dms.dot.gov/). 

2. On that page, click on ‘‘search.’’


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29 49 U.S.C. 30111(a). 

30 49 U.S.C. 30102(a)(9). 

31 49 U.S.C. 30111(b). 

32 Id. 

33 49 U.S.C. 105 and 322; delegation of authority 

at 49 CFR 1.50. 

3. On the next page (http:// 

dms.dot.gov/search/), type in the fourdigit docket number shown at the 

beginning of this document. (Example: 

If the docket number were ‘‘NHTSA–

1998–1234,’’ you would type ‘‘1234.’’) 

After typing the docket number, click on 

‘‘search.’’

4. On the next page, which contains 

docket summary information for the 

docket you selected, click on the desired 

comments. You may download the 

comments. Although the comments are 

imaged documents, instead of word 

processing documents, the ‘‘pdf’’

versions of the documents are word 

searchable. 

Please note that even after the 

comment closing date, we will continue 

to file relevant information in the 

Docket as it becomes available. Further, 

some people may submit late comments. 

Accordingly, we recommend that you 

periodically check the Docket for new 

material. 

Data Quality Act Statement 

Pursuant to the Data Quality Act, in 

order for substantive data submitted by 

third parties to be relied upon and used 

by the agency, it must also meet the 

information quality standards set forth 

in the DOT Data Quality Act guidelines. 

Accordingly, members of the public 

should consult the guidelines in 

preparing information submissions to 

the agency. DOT’s guidelines may be 

accessed at http://dmses.dot.gov/ 

submit/DataQualityGuidelines.pdf. 

IX. Regulatory Analyses and Notices 

A. Vehicle 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 that are 

practicable, meet the need for motor 

vehicle safety, and are stated in 

objective terms.29 These motor vehicle 

safety standards set the minimum level 

of performance for a motor vehicle or 

motor vehicle equipment to be 

considered safe.30 When prescribing 

such standards, the Secretary must 

consider all relevant, available motor 

vehicle safety information.31 The 

Secretary also must consider whether a 

proposed standard is reasonable, 

practicable, and appropriate for the type 

of motor vehicle 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.32 The responsibility for 

promulgation of Federal motor vehicle 

safety standards has been delegated to 

NHTSA.33

As noted previously, section 10301 of 

SAFETEA–LU mandated a regulation to 

reduce the occurrence of rollovers 

‘‘consistent with stability enhancing 

technologies.’’ In developing this 

proposed rule for ESC, the agency 

carefully considered the statutory 

requirements of both SAFETEA–LU and 

49 U.S.C. Chapter 301. 

First, in preparing this document, the 

agency carefully evaluated available 

research, testing results, and other 

information related to ESC technology. 

The agency performed extensive 

research on its own and made use of 

research performed by the Alliance of 

Automobile Manufacturers. We have 

also performed analyses of ESC using 

actual crash data to determine the 

effectiveness of ESC in reducing singlevehicle crashes and rollovers. In sum, 

this document reflects our consideration 

of all relevant, available motor vehicle 

safety information. 

Second, to ensure that the ESC 

requirements are practicable, the agency 

research and the Alliance research 

documented the capabilities of current 

ESC systems and dynamic performance 

of model year 2005 vehicles equipped 

with them. We have tentatively 

concluded that all current production 

vehicles equipped with ESC systems 

would comply with the equipment 

requirements, that all but one vehicle 

would comply with the performance 

tests proposed, and that only minor 

software tuning would be required to 

bring that vehicle into compliance. In 

sum, we believe that this proposed rule 

is practicable, in that it could be 

implemented with existing technology 

and is quite cost effective given its 

potential to prevent thousands of deaths 

and injuries each year, particularly 

those associated with single-vehicle 

crashes leading to rollover. 

Third, the regulatory text following 

this preamble is stated in objective 

terms in order to specify precisely what 

equipment constitutes an ESC system, 

what performance is required and how 

performance would be tested under the 

standard. The proposed definition of an 

ESC system is based on an industry 

consensus definition developed by the 

Society of Automotive Engineers (SAE). 

The proposed rule also includes 

performance requirements and test 

procedures for the timing and intensity 

of the oversteer intervention of the ESC 

system and the responsiveness of the 

vehicle. This test procedure involves a 

precisely defined steering pattern 

performed by a robotic steering machine 

under a defined set of test conditions 

(e.g., ambient temperature, road test 

surface, vehicle load, vehicle speed). 

Performance is defined by objective 

measurements of yaw rate and lateral 

acceleration taken by scientific 

instruments at precise times with 

reference to the steering pattern. The 

standard’s test procedures carefully 

delineate how testing would be 

conducted. Thus, the agency believes 

that this test procedure is sufficiently 

objective and would not result in any 

uncertainty as to whether a given 

vehicle satisfies the requirements of the 

ESC standard. 

Finally, we believe that this proposed 

rule is reasonable and appropriate for 

motor vehicles subject to the applicable 

requirements. As discussed elsewhere 

in this notice, the agency is addressing 

Congress’ concern about rollover 

crashes resulting in fatalities and 

serious injuries. Under section 10301 of 

SAFETEA–LU, Congress mandated 

installation of stability enhancing 

technologies in new vehicles to reduce 

rollovers. NHTSA has determined that 

ESC systems meeting the requirements 

of this proposed rule offer an effective 

countermeasure to rollover crashes and 

to other single-vehicle and certain 

multi-vehicle crashes. Accordingly, we 

believe that this proposed rule is 

appropriate for vehicles that would 

become subject to these provisions 

because it furthers the agency’s 

objective of preventing deaths and 

serious injuries, particularly those 

associated with rollover crashes. 

B. Executive Order 12866 and DOT 

Regulatory Policies and Procedures 

Executive Order 12866, ‘‘Regulatory 

Planning and Review’’ (58 FR 51735, 

October 4, 1993), provides for making 

determinations whether a regulatory 

action is ‘‘significant’’ and therefore 

subject to Office of Management and 

Budget (OMB) review and to the 

requirements of the Executive Order. 

The Order defines a ‘‘significant 

regulatory action’’ as one that is likely 

to result in a rule that may: 

(1) Have an annual effect on the 

economy of $100 million or more or 

adversely affect in a material way the 

economy, a sector of the economy, 

productivity, competition, jobs, the 

environment, public health or safety, or 

State, local, or Tribal governments or 

communities; 

(2) Create a serious inconsistency or 

otherwise interfere with an action taken 

or planned by another agency; 


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(3) Materially alter the budgetary 

impact of entitlements, grants, user fees, 

or loan programs or the rights and 

obligations of recipients thereof; or 

(4) Raise novel legal or policy issues 

arising out of legal mandates, the 

President’s priorities, or the principles 

set forth in the Executive Order. 

We have considered the impact of this 

action under Executive Order 12866 and 

the Department of Transportation’s 

regulatory policies and procedures. This 

action has been determined to be 

economically significant under the 

Executive Order, and it is also a subject 

of congressional interest and a mandate 

under section 10301 of SAFETEA–LU. 

The agency has prepared and placed in 

the docket a Preliminary Regulatory 

Impact Analysis. This rulemaking action 

is also significant within the meaning of 

the Department of Transportation’s 

Regulatory Policies and Procedures (44 

FR 11034; February 26, 1979). 

Accordingly, this rulemaking document 

was reviewed by the Office of 

Management and Budget under 

Executive Order 12866, ‘‘Regulatory 

Planning and Review.’’ The agency has 

estimated that compliance with this 

proposal would cost approximately 

$985 million per year and have net 

benefits as high as $10.6 billion per 

year. Thus, this rule would have greater 

than a $100 million effect. 

C. Regulatory Flexibility Act 

Pursuant to the Regulatory Flexibility 

Act of 1980 (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 a notice of 

rulemaking for any proposed or final 

rule, it must prepare and make available 

for public comment a regulatory 

flexibility analysis that describes the 

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

small businesses, small organizations, 

and small governmental jurisdictions). 

However, no regulatory or 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. 

NHTSA has considered the effects of 

this rulemaking action under the 

Regulatory Flexibility Act and has 

included an initial regulatory flexibility 

analysis in the PRE. This analysis 

discusses potential regulatory 

alternatives that the agency considered 

that would still meet the identified 

safety need of reducing the occurrence 

of rollovers through stability enhancing 

technologies. Alternatives considered 

included (a) applying the standard to 

light trucks but not to passenger cars 

and (b) permitting front-wheel-only ESC 

systems that are incapable of understeer 

intervention. The first alternative was 

rejected because passenger car ESC 

systems would save 956 lives and 

reduce 34,902 injuries annually at a cost 

per equivalent fatality that would easily 

justify a separate rule for passenger cars. 

The second alternative was rejected 

because front-wheel-only ESC systems 

would prevent 30 percent fewer singlevehicle crashes without producing a 

large cost saving. 

To summarize the conclusions of that 

analysis, the agency believes that the 

proposal would have a significant 

economic impact on a substantial 

number of small businesses. There are 

currently four small domestic motor 

vehicle manufacturers in the United 

States, each having fewer than 1,000 

employees. Although the cost for an 

ESC system is relatively high, we 

believe that these manufacturers would 

be able to pass the associated costs on 

to purchasers without decreasing sales 

volume, because the demand for these 

high-end, luxury vehicles tends to be 

inelastic and the increase in total 

vehicle cost is expected to be only 0.2–

1.1 percent. 

There are a significant number of 

final-stage manufacturers and alterers 

that could be impacted by the proposed 

rule for ESC, some of which buy 

incomplete vehicles. However, finalstage manufacturers and alterers 

typically do not modify the brake 

system of the vehicle, so the original 

manufacturer’s certification of the ESC 

system should pass through for these 

vehicles. We believe that increased costs 

associated with ESC would impact all 

such final-stage manufacturers and 

alterers equally, and that such costs 

would be passed on to consumers. 

Furthermore, we have no reason to 

believe that an average cost of $90 per 

passenger car and $29 per truck will 

cause a significant decline in overall 

vehicle sales. 

We do not expect manufacturers of 

ESC systems to be classified as small 

businesses. 

D. Executive Order 13132 (Federalism) 

Executive Order 13132 sets forth 

principles of federalism and the related 

policies of the Federal government. 

NHTSA has analyzed this rule in 

accordance with the principles and 

criteria set forth in Executive Order 

13132, Federalism, and has determined 

that it does not have sufficient Federal 

implications to warrant consultation 

with State and local officials or the 

preparation of a Federalism summary 

impact statement. The rule will not have 

any substantial impact on the States, or 

on the current Federal-State 

relationship, or on the current 

distribution of power and 

responsibilities among the various local 

officials. However, under 49 U.S.C. 

30103, whenever a Federal motor 

vehicle safety standard is in effect, a 

State may not adopt or maintain a safety 

standard applicable to the same aspect 

of performance which is not identical to 

the Federal standard, except to the 

extent that the state requirement 

imposes a higher level of performance 

and applies only to vehicles procured 

for the State’s use. 

E. Executive Order 12988 (Civil Justice 

Reform) 

Pursuant to Executive Order 12988, 

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

February 7, 1996), the agency has 

considered whether this proposed rule 

would have any retroactive effect. This 

proposed rule would not have any 

retroactive effect. Under 49 U.S.C. 

30103, whenever a Federal motor 

vehicle safety standard is in effect, a 

State may not adopt or maintain a safety 

standard applicable to the same aspect 

of performance of a motor vehicle or 

motor vehicle equipment which is not 

identical to the Federal standard, except 

to the extent that the State requirement 

imposes a higher level of performance 

and applies only to vehicles procured 

for the State’s use. 49 U.S.C. 30161 sets 

forth a procedure for judicial review of 

final rules establishing, amending, or 

revoking Federal motor vehicle safety 

standards. That section does not require 

submission of a petition for 

reconsideration or other administrative 

proceedings before parties may file suit 

in court. 

F. Executive Order 13045 (Protection of 

Children From Environmental Health 

and Safety Risks) 

Executive Order 13045, ‘‘Protection of 

Children from Environmental Health 

and Safety Risks’’ (62 FR 19855, April 

23, 1997), applies to any rule that: (1) 

Is determined to be ‘‘economically 

significant’’ as defined under Executive 

Order 12866, and (2) concerns an 

environmental, health, or safety risk that 

the agency has reason to believe may 

have a disproportionate effect on 

children. If the regulatory action meets 

both criteria, the agency must evaluate 

the environmental health or safety 

effects of the planned rule on children, 

and explain why the planned regulation 


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is preferable to other potentially 

effective and reasonably feasible 

alternatives considered by the agency. 

Although the proposed rule for ESC 

has been determined to be an 

economically significant regulatory 

action under Executive Order 12866, the 

problems associated with loss of vehicle 

control equally impact all persons 

riding in a vehicle, regardless of age. 

Consequently, the proposed rule does 

not involve a decision based on 

environmental, health, or safety risks 

that disproportionately affect children 

and would not necessitate further 

analyses under Executive Order 13045. 

G. Paperwork Reduction Act 

Under the Paperwork Reduction Act 

of 1995 (PRA), 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. The Department of 

Transportation is submitting the 

following information collection request 

to OMB for review and clearance under 

the PRA. 

Agency: National Highway Traffic 

Safety Administration (NHTSA). 

Title: Phase-In Production Reporting 

Requirements for Electronic Stability 

Control Systems. 

Type of Request: Routine. 

OMB Clearance Number: 2127–New. 

Form Number: This collection of 

information will not use any standard 

forms. 

Affected Public: The respondents are 

manufacturers of passenger cars, 

multipurpose passenger vehicles, 

trucks, and buses having a gross vehicle 

weight rating of 4,536 Kg (10,000 

pounds) or less. The agency estimates 

that there are about 21 such 

manufacturers. 

Estimate of the Total Annual 

Reporting and Recordkeeping Burden 

Resulting From the Collection of 

Information: NHTSA estimates that the 

total annual hour burden is 42 hours. 

Estimated Costs: NHTSA estimates 

that the total annual cost burden, in U.S. 

dollars, will be $2,100. No additional 

resources would be expended by vehicle 

manufacturers to gather annual 

production information because they 

already compile this data for their own 

uses. 

Summary of Collection of 

Information: This collection would 

require manufacturers of passenger cars, 

multipurpose passenger vehicles, 

trucks, and buses with a gross vehicle 

weight rating of 4,536 Kg (10,000 

pounds) or less to provide motor vehicle 

production data for the following three 

years: September 1, 2008 to August 31, 

2009; September 1, 2009 to August 31, 

2010; and September 1, 2010 to August 

31, 2011. 

Description of the Need for the 

Information and the Proposed Use of 

the Information: The purpose of the 

reporting requirements will be to aid 

NHTSA in determining whether a 

manufacturer has complied with the 

requirements of Federal Motor Vehicle 

Safety Standard No. 126, Electronic 

Stability Control Systems, during the 

phase-in of those requirements. NHTSA 

requests comments on the agency’s 

estimates of the total annual hour and 

cost burdens resulting from this 

collection of information. These 

comments must be received on or before 

October 18, 2006. 

H. National Technology Transfer and 

Advancement Act 

Section 12(d) of the National 

Technology Transfer and Advancement 

Act of 1995 (NTTAA), Public Law 104–

113, section 12(d) (15 U.S.C. 272) 

directs NHTSA to use voluntary 

consensus standards in its regulatory 

activities unless doing so would be 

inconsistent with applicable law or 

otherwise impractical. 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 the Society of 

Automotive Engineers (SAE). The 

NTTAA directs NHTSA to provide 

Congress, through OMB, explanations 

when the agency decides not to use 

available and applicable voluntary 

consensus standards. The NTTAA does 

not apply to symbols. 

The equipment requirements of this 

standard are based (with minor 

modifications) on the SAE Surface 

Vehicle Information Report on 

Automotive Stability Enhancement 

Systems J2564 Rev JUN2004 that 

provides an industry consensus 

definition of an ESC system. However, 

there is no voluntary consensus 

standard for ESC that contains any 

specifications for a performance test. 

I. Unfunded Mandates Reform Act 

Section 202 of the Unfunded 

Mandates Reform Act of 1995 (UMRA) 

requires Federal 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 expenditure by 

State, local or tribal governments, in the 

aggregate, or by the private sector, of 

more than $100 million in any one year 

(adjusted for inflation with base year of 

1995, so currently about $118 million in 

2004 dollars). Before promulgating a 

rule for which a written statement is 

needed, section 205 of the UMRA 

generally requires NHTSA to identify 

and consider a reasonable number of 

regulatory alternatives and adopt the 

least costly, most cost-effective, or least 

burdensome alternative that achieves 

the objectives of the rule. The 

provisions of section 205 do not apply 

when they are inconsistent with 

applicable law. Moreover, section 205 

allows NHTSA to adopt an alternative 

other than the least costly, most costeffective or least burdensome alternative 

if we publish with the final rule an 

explanation why that alternative was 

not adopted. 

This proposal would not result in the 

expenditure by State, local, or tribal 

governments, in the aggregate, of more 

than $118 million annually, but it 

would result in the expenditure of that 

magnitude by vehicle manufacturers 

and/or their suppliers. 

In this proposed rule, the agency is 

presenting not only its proposed 

regulatory approach for ESC, but also 

the regulatory alternatives it has 

considered. In addition, as part of the 

public comment process, the agency is 

open to suggestions regarding ways to 

promote flexibility and to minimize 

costs of compliance, while achieving the 

safety purposes of the Safe, 

Accountable, Flexible, Efficient 

Transportation Equity Act: A Legacy for 

Users of 2005. 

J. National Environmental Policy Act 

NHTSA has analyzed this proposed 

rulemaking action for the purposes of 

the National Environmental Policy Act. 

The agency has determined that 

implementation of this action would not 

have any significant impact on the 

quality of the human environment. 

K. 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. 

L. Privacy Act 

Please note that anyone is able to 

search the electronic form of all 

comments 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 


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Privacy Act Statement in the Federal 

Register published on April 11, 2000 

(Volume 65, Number 70; pages 19477–

78) or you may visit http://dms.dot.gov. 

BILLING CODE 4910–59–P 


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Figures to Preamble 


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Proposed Regulatory Text 

List of Subjects in 49 CFR Parts 571 and 

585 

Imports, Motor vehicle safety, Report 

and recordkeeping requirements, Tires. 

In consideration of the foregoing, 

NHTSA is proposing to amend 49 CFR 

parts 571 and 585 as follows: 

PART 571—FEDERAL MOTOR 

VEHICLE SAFETY STANDARDS 

1. The authority citation for part 571 

continues to read as follows: 

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

30117, and 30166; delegation of authority at 

49 CFR 1.50. 

2. Section 571.101 is amended by 

revising Table 1 to read as follows: 

§ 571.101 Standard No. 101; Controls and 

displays. 

* * * * * 


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BILLING CODE 4910–59–C 


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* * * * * 

3. Section 571.126 is added to read as 

follows: 

§ 571.126 Standard No. 126; Electronic 

stability control systems. 

S1. Scope. This standard establishes 

performance and equipment 

requirements for electronic stability 

control (ESC) systems. 

S2. Purpose. The purpose of this 

standard is to reduce the number of 

deaths and injuries that result from 

crashes in which the driver loses 

directional control of the vehicle. 

S3. Application. This standard 

applies to passenger cars, multipurpose 

passenger vehicles, trucks, and buses 

with a gross vehicle weight rating of 

4,536 kilograms (10,000 pounds) or less, 

according to the phase-in schedule 

specified in S8 of this standard. 

S4. Definitions. 

Ackerman Steer Angle means the 

angle whose tangent is the wheelbase 

divided by the radius of the turn at a 

very low speed. 

Electronic Stability Control System or 

ESC System means a system that has all 

of the following attributes: 

(1) That augments vehicle directional 

stability by applying and adjusting the 

vehicle brakes individually to induce 

correcting yaw torques to a vehicle; 

(2) That is computer controlled with 

the computer using a closed-loop 

algorithm to limit vehicle oversteer and 

to limit vehicle understeer when 

appropriate; 

(3) That has a means to determine the 

vehicle’s yaw rate and to estimate its 

side slip; 

(4) That has a means to monitor driver 

steering inputs, and 

(5) That is operational over the full 

speed range of the vehicle (except below 

a low-speed threshold where loss of 

control is unlikely). 

Oversteer means a condition in which 

the vehicle’s yaw rate is greater than the 

yaw rate that would occur at the 

vehicle’s speed as result of the 

Ackerman Steer Angle. 

Sideslip or side slip angle means the 

arctangent of the lateral velocity of the 

center of gravity of the vehicle divided 

by the longitudinal velocity of the 

center of gravity. 

Understeer means a condition in 

which the vehicle’s yaw rate is less than 

the yaw rate that would occur at the 

vehicle’s speed as result of the 

Ackerman Steer Angle. 

Yaw rate means the rate of change of 

the vehicle’s heading angle measured in 

degrees/second of rotation about a 

vertical axis through the vehicle’s center 

of gravity. 

S5. Requirements. Subject to the 

phase-in set forth in S8, each vehicle 

must be equipped with an ESC system 

that meets the requirements specified in 

S5 under the test conditions specified in 

S6 and the test procedures specified in 

S7 of this standard. 

S5.1 Required Equipment. Vehicles 

to which this standard applies must be 

equipped with an electronic stability 

control system that: 

S5.1.1 Is capable of applying all four 

brakes individually and has a control 

algorithm that utilizes this capability. 

S5.1.2 Is operational during all 

phases of driving including 

acceleration, coasting, and deceleration 

(including braking), except when the 

driver has disabled ESC or the vehicle 

is below a low speed threshold where 

loss of control is unlikely. 

S5.1.3 Remains operational when 

the antilock brake system or traction 

control system is activated. 

S5.2 Performance Requirements. 

During each test performed under the 

test conditions of S6 and the test 

procedure of S7.9, the vehicle with the 

ESC system engaged must satisfy the 

stability criteria of S5.2.1 and S5.2.2, 

and it must satisfy the responsiveness 

criterion of S5.2.3 during each of those 

tests conducted with a steering angle 

amplitude of 180 degrees or greater. 

S5.2.1 The yaw rate measured one 

second after completion of the sine with 

dwell steering input (time T0 + 1 in 

Figure 1) must not exceed 35 percent of 

the first peak value of yaw velocity 

recorded after the beginning of the 

dwell period 

during the same test run, and 

S5.2.2 The yaw rate measured 1.75 

seconds after completion of the sine 

with dwell steering input must not 

exceed 20 percent of the first peak value 

of yaw velocity recorded after the 

beginning of the dwell period during the 

same test run. 

S5.2.3 The lateral displacement of 

the vehicle center of gravity with 

respect to its initial straight path must 

be at least 1.83 m (6 feet) when 

computed 1.07 seconds after initiation 

of steering. 

S5.2.3.1 The computation of lateral 

displacement is performed using double 

integration with respect to time of the 

measurement of lateral acceleration at 

the vehicle center of gravity, as 

expressed by the formula: 

Lateral Displacement = ∫∫Ayc.g.dt 

S5.2.3.2 Time, t = 0 for the 

integration operation is the instant of 

steering initiation. 

S5.3 ESC Malfunction. The vehicle 

must be equipped with a telltale that 

provides a warning to the driver not 

more than two minutes after the 

occurrence of one or more malfunctions 

that affect the generation or 

transmission of control or response 

signals in the vehicle’s electronic 

stability control system. The ESC 

malfunction telltale: 

S5.3.1 Must be mounted inside the 

occupant compartment in front of and 

in clear view of the driver; 

S5.3.2 Must be identified by the 

symbol shown for ‘‘ESC Malfunction 

Telltale’’ in Table 1 of Standard No. 101 

(49 CFR 571.101); 

S5.3.3 Must remain continuously 

illuminated under the conditions 

specified in S5.3 for as long as the 

malfunction(s) exists, whenever the 

ignition locking system is in the ‘‘On’’

(‘‘Run’’) position; and 

S5.3.4 Except as provided in 

paragraph S5.3.5, each ESC malfunction 

telltale must be activated as a check of 

lamp function either when the ignition 

locking system is turned to the ‘‘On’’

(‘‘Run’’) position when the engine is not 

running, or when the ignition locking 

system is in a position between ‘‘On’’

(‘‘Run’’) and ‘‘Start’’ that is designated 

by the manufacturer as a check position. 

S5.3.5 The ESC malfunction telltale 

need not be activated when a starter 

interlock is in operation. 

S5.3.6 The ESC malfunction telltale 

must extinguish after the malfunction 

has been corrected. 

S5.3.7 The manufacturer may use 

the ESC malfunction telltale in a 

flashing mode to indicate ESC 

operation. 

S5.4 ESC Off Switch and Telltale. 

The manufacturer may include a driver 

selectable switch that places the ESC 

system in a mode in which it will not 

satisfy the performance requirements of 

S5.2.1, S5.2.2 and S5.2.3 provided that: 

S5.4.1 The vehicle’s ESC system 

must always return to a mode that 

satisfies the requirements of S5.1 and 

S5.2 at the initiation of each new 

ignition cycle, regardless of what mode 

the driver had previously selected. If the 

system has more than one mode that 

satisfies these requirements, the default 

mode must be the mode that satisfies 

the performance requirements of S5.2 by 

the greatest margin. 

S5.4.2 The vehicle manufacturer 

must provide a telltale indicating that 

the vehicle has been put into a mode 

that renders it unable to satisfy the 

requirements of S5.2.1, S5.2.2 and 

S5.2.3. 

S5.4.3 The ‘‘ESC Off’’ switch and 

telltale must be identified by the symbol 

shown for ‘‘ESC Off’’ in Table 1 of 

Standard No. 101 (49 CFR 571.101). 

S5.4.4 The ‘‘ESC Off’’ telltale must 

be mounted inside the occupant 


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compartment in front of and in clear 

view of the driver. 

S5.4.5 The ‘‘ESC Off’’ telltale remain 

continuously illuminated for as long as 

the ESC is in a mode that renders it 

unable to satisfy the requirements of 

S5.2.1, S5.2.2 and S5.2.3, and 

S5.4.6 Except as provided in 

paragraph S5.4.7, each ‘‘ESC Off’’

telltale must be activated as a check of 

lamp function either when the ignition 

locking system is turned to the ‘‘On’’

(‘‘Run’’) position when the engine is not 

running, or when the ignition locking 

system is in a position between ‘‘On’’

(‘‘Run’’) and ‘‘Start’’ that is designated 

by the manufacturer as a check position. 

S5.4.7 The ‘‘ESC Off’’ telltale need 

not be activated when a starter interlock 

is in operation. 

S5.4.8 The ‘‘ESC Off’’ telltale must 

extinguish after the ESC system has 

been returned to its fully functional 

default mode. 

S6. Test Conditions. 

S6.1. Ambient conditions. 

S6.1.1 The ambient temperature is 

between 0 °C (32 °F) and 40 °C (104 °F). 

S6.1.2 The maximum wind speed is 

no greater than 10m/s (22 mph). 

S6.2. Road test surface. 

S6.2.1 The tests are conducted on a 

dry, uniform, solid-paved surface. 

Surfaces with irregularities and 

undulations, such as dips and large 

cracks, are unsuitable. 

S6.2.2 The road test surface must 

produce a peak friction coefficient (PFC) 

of 0.9 ± 0.05 when measured using an 

American Society for Testing and 

Materials (ASTM) E1136 standard 

reference test tire, in accordance with 

ASTM Method E 1337–90, at a speed of 

64.4 km/h (40 mph), without water 

delivery. 

S6.2.3 The test surface has a 

consistent slope between level and 2%. 

All tests are to be initiated in the 

direction of positive slope (uphill). 

S6.3 Vehicle conditions. 

S6.3.1 The ESC system is enabled 

for all testing. 

S6.3.2 Test Weight. The vehicle is 

loaded with the fuel tank filled to at 

least 75 percent of capacity, and total 

interior load of 168 kg (370 lbs) 

comprised of the test driver, 

approximately 59 kg (130 lbs) of test 

equipment (automated steering 

machine, data acquisition system and 

the power supply for the steering 

machine), and ballast as required by 

differences in the weight of test drivers 

and test equipment. 

S6.3.3 Tires. The vehicle is tested 

with the tires installed on the vehicle at 

time of initial vehicle sale. The tires are 

inflated to the vehicle manufacturer’s 

recommended cold tire inflation 

pressure(s) specified on the vehicle’s 

placard or the tire inflation pressure 

label. Tubes may be installed to prevent 

tire de-beading. 

S6.3.4 Outriggers. Outriggers must 

be used for tests of Sport Utility 

Vehicles (SUVs), and they are permitted 

on other test vehicles if deemed 

necessary for driver safety. 

S6.3.5 A steering machine 

programmed to execute the required 

steering pattern must be used in S7.5.2, 

S7.5.3, S7.6 and S7.9. 

S7. Test Procedure. 

S7.1 Inflate the vehicles’ tires to the 

cold tire inflation pressure(s) provided 

on the vehicle’s placard or the tire 

inflation pressure label. 

S7.2 Telltale bulb check. With the 

vehicle stationary and the ignition 

locking system in the ‘‘Lock’’ or ‘‘Off’’

position, activate the ignition locking 

system to the ‘‘On’’ (‘‘Run’’) position or, 

where applicable, the appropriate 

position for the lamp check. The ESC 

system must perform a check of lamp 

function for the ESC malfunction 

telltale, and if equipped, the ‘‘ESC Off’’

telltale, as specified in S5.3.4 and 

S5.4.6. 

S7.3 ‘‘ESC Off’’ switch check. For 

vehicles equipped with an ‘‘ESC Off’’

feature, with the vehicle stationary and 

the ignition locking system in the 

‘‘Lock’’ or ‘‘Off’’ position, activate the 

ignition locking system to the ‘‘On’’

(‘‘Run’’) position. Activate the ‘‘ESC 

Off’’ switch and verify that the ‘‘ESC 

Off’’ telltale is illuminated. Turn the 

ignition locking system to the ‘‘Lock’’ or 

‘‘Off’’ position. Again, activate the 

ignition locking system to the ‘‘On’’

(‘‘Run’’) position and verify that the 

‘‘ESC Off’’ telltale has extinguished 

indicating that the ESC system has been 

reactivated as specified in S5.4. 

S7.4 Brake Conditioning. Condition 

the vehicle brakes as follows: 

S7.4.1 Ten stops are performed from 

a speed of 56 km/h (35 mph), with an 

average deceleration of approximately 

0.5 g. 

S7.4.2 Immediately following the 

series of 56 km/h (35 mph) stops, three 

additional stops are performed from 72 

km/h (45 mph). 

S7.4.3 When executing the stops in 

S7.4.2, sufficient force is applied to the 

brake pedal to activate the vehicle’s 

antilock brake system (ABS) for a 

majority of each braking event. 

S7.4.4 Following completion of the 

final stop in S7.4.2, the vehicle is driven 

at a speed of 72 km/h (45 mph) for five 

minutes to cool the brakes. 

S7.5 Tire Conditioning. Condition 

the tires using the following procedure 

to wear away mold sheen and achieve 

operating temperature immediately 

before beginning the test runs of S7.6 

and S7.9. 

S7.5.1 The test vehicle is driven 

around a circle 30 meters (100 feet) in 

diameter at a speed that produces a 

lateral acceleration of approximately 0.5 

to 0.6 g for three clockwise laps 

followed by three counterclockwise 

laps. 

S7.5.2 Using a sinusoidal steering 

pattern at a frequency of 1 Hz, a peak 

steering wheel angle amplitude 

corresponding to a peak lateral 

acceleration of 0.5–0.6 g, and a vehicle 

speed of 56 km/h (35 mph), the vehicle 

is driven through four passes 

performing 10 cycles of sinusoidal 

steering during each pass. 

S7.5.3 The steering wheel angle 

amplitude of the final cycle of the final 

pass is twice that of the other cycles. 

The maximum time permitted between 

all laps and passes is five minutes. 

S7.6 Slowly Increasing Steer Test. 

The vehicle is subjected to two series of 

runs of the Slowly Increasing Steer Test 

using a steering pattern that increases by 

13.5 degrees per second until a lateral 

acceleration of approximately 0.5 g is 

obtained. Three repetitions are 

performed for each test series. One 

series uses counterclockwise steering, 

and the other series uses clockwise 

steering. The maximum time permitted 

between each test run is five minutes. 

S7.6.1 From the Slowly Increasing 

Steer tests, the quantity ‘‘A’’ is 

determined. ‘‘A’’ is the steering wheel 

angle in degrees that produces a steady 

state lateral acceleration of 0.3 g for the 

test vehicle. Utilizing linear regression, 

A is calculated, to the nearest 0.1 

degrees, from each of the six Slowly 

Increasing Steer tests. The absolute 

value of the six A’s calculated is 

averaged and rounded to the nearest 

degree to produce the final quantity, A, 

used below. 

S7.7 After the quantity A has been 

determined, without replacing the tires, 

the tire conditioning procedure 

described in S7.5 is performed 

immediately prior to conducting the 

Sine with Dwell Test of S7.9. 

S7.8 Check that the ESC system is 

enabled by ensuring that the ESC 

malfunction and ‘‘ESC Off’’ (if provided) 

telltales are not illuminated. 

S7.9 Sine with Dwell Test of 

Oversteer Intervention and 

Responsiveness. The vehicle is 

subjected to two series of test runs using 

a steering pattern of a sine wave at 0.7 

Hz frequency with a 500 ms delay 

beginning at the second peak amplitude 

as shown in Figure 2 (the Sine with 

Dwell tests). One series uses 

counterclockwise steering for the first 

half cycle, and the other series uses 


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clockwise steering for the first half 

cycle. The maximum time permitted 

between each test run is five minutes. 

S7.9.1 The steering motion is 

initiated with the vehicle coasting in 

high gear at 80 ± 1 km/h (50 ± 1 mph). 

S7.9.2 In each series of test runs, the 

steering amplitude is increased from run 

to run, by 0.5A, provided that no such 

run will result in a steering amplitude 

greater than that of the final run 

specified in S7.9.4. 

S7.9.3 The steering amplitude for 

the initial run of each series is 1.5A 

where A is the steering wheel angle 

determined in S7.6.1. 

S7.9.4 The steering amplitude of the 

final run in each series is the greater of 

6.5A or 270 degrees. 

S7.9.5 Notwithstanding S7.9.4, the 

test is terminated after a run in which 

the vehicle does not satisfy S5.2.1 or 

S5.2.2. 

S7.10 ESC Malfunction Detection. 

S7.10.1 Simulate one or more ESC 

malfunction(s) by disconnecting the 

power source to any ESC component, or 

disconnecting any electrical connection 

between ESC components. When 

simulating an ESC malfunction, the 

electrical connections for the telltale 

lamp(s) are not to be disconnected. 

S7.10.2 With the vehicle stationary 

and the ignition locking system in the 

‘‘Lock’’ or ‘‘Off’’ position, activate the 

ignition locking system to the ‘‘On’’

(‘‘Run’’) position. Verify that within two 

minutes of activating the ignition 

locking system, the ESC malfunction 

indicator illuminates in accordance 

with S5.3. 

S7.10.3 Deactivate the ignition 

locking system to the ‘‘Off’’ or ‘‘Lock’’

position. After a five-minute period, 

activate the vehicle’s ignition locking 

system to the ‘‘On’’ (‘‘Run’’) position. 

Verify that the ESC malfunction 

indicator again illuminate to signal a 

malfunction and remains illuminated as 

long as the ignition locking system is in 

the ‘‘On’’ (‘‘Run’’) position. 

S7.10.4 Restore the ESC system to 

normal operation and verify that the 

telltale has extinguished. 

S8 Phase-in schedule. 

S8.1 Vehicles manufactured on or 

after September 1, 2008, and before 

September 1, 2009. For vehicles 

manufactured on or after September 1, 

2008, and before September 1, 2009, the 

number of vehicles complying with this 

standard must not be less than 30 

percent of: 

(a) The manufacturer’s average annual 

production of vehicles manufactured on 

or after September 1, 2005, and before 

September 1, 2008; or 

(b) The manufacturer’s production on 

or after September 1, 2008, and before 

September 1, 2009. 

S8.2 Vehicles manufactured on or 

after September 1, 2009, and before 

September 1, 2010. For vehicles 

manufactured on or after September 1, 

2009, and before September 1, 2010, the 

number of vehicles complying with this 

standard must not be less than 60 

percent of: 

(a) The manufacturer’s average annual 

production of vehicles manufactured on 

or after September 1, 2006, and before 

September 1, 2009; or 

(b) The manufacturer’s production on 

or after September 1, 2009, and before 

September 1, 2010. 

S8.3 Vehicles manufactured on or 

after September 1, 2010, and before 

September 1, 2011. For vehicles 

manufactured on or after September 1, 

2010, and before September 1, 2011, the 

number of vehicles complying with this 

standard must not be less than 90 

percent of: 

(a) The manufacturer’s average annual 

production of vehicles manufactured on 

or after September 1, 2007, and before 

September 1, 2010; or 

(b) The manufacturer’s production on 

or after September 1, 2010, and before 

September 1, 2011. 

S8.4 Vehicles manufactured on or 

after September 1, 2011. All vehicles 

manufactured on or after September 1, 

2011 must comply with this standard. 

S8.5 Calculation of complying 

vehicles. 

(a) For purposes of complying with 

S8.1, a manufacturer may count a 

vehicle if it is certified as complying 

with this standard and is manufactured 

on or after (date to be inserted that is 60 

days after publication date of final rule), 

but before September 1, 2009. 

(b) For purpose of complying with 

S8.2, a manufacturer may count a 

vehicle if it: 

(1)(i) Is certified as complying with 

this standard and is manufactured on or 

after (date to be inserted that is 60 days 

after date of publication of the final 

rule), but before September 1, 2010; and 

(ii) Is not counted toward compliance 

with S8.1; or 

(2) Is manufactured on or after 

September 1, 2009, but before 

September 1, 2010. 

(c) For purposes of complying with 

S8.3, a manufacturer may count a 

vehicle if it: 

(1)(i) Is certified as complying with 

this standard and is manufactured on or 

after (date to be inserted that is 60 days 

after date of publication of the final 

rule), but before September 1, 2011; and 

(ii) Is not counted toward compliance 

with S8.1 or S8.2; or 

(2) Is manufactured on or after 

September 1, 2010, but before 

September 1, 2011. 

S8.6 Vehicles produced by more 

than one manufacturer. 

S8.6.1 For the purpose of calculating 

average annual production of vehicles 

for each manufacturer and the number 

of vehicles manufactured by each 

manufacturer under S8.1 through S8.4, 

a vehicle produced by more than one 

manufacturer must be attributed to a 

single manufacturer as follows, subject 

to S8.6.2: 

(a) A vehicle that is imported must be 

attributed to the importer. 

(b) A vehicle manufactured in the 

United States by more than one 

manufacturer, one of which also 

markets the vehicle, must be attributed 

to the manufacturer that markets the 

vehicle. 

S8.6.2 A vehicle produced by more 

than one manufacturer must be 

attributed to any one of the vehicle’s 

manufacturers specified by an express 

written contract, reported to the 

National Highway Traffic Safety 

Administration under 49 CFR Part 585, 

between the manufacturer so specified 

and the manufacturer to which the 

vehicle would otherwise be attributed 

under S8.6.1. 

S8.7 Small volume manufacturers. 

Vehicles manufactured during any of 

the three years of the September 1, 2008 

through August 31, 2011 phase-in by a 

manufacturer that produces fewer than 

5,000 vehicles for sale in the United 

States during that year are not subject to 

the requirements of S8.1, S8.2, S8.3, and 

S8.5 

S8.8 Final-stage manufacturers and 

alterers. 

Vehicles that are manufactured in two 

or more stages or that are altered (within 

the meaning of 49 CFR 567.7) after 

having previously been certified in 

accordance with Part 567 of this chapter 

are not subject to the requirements of 

S8.1 through S8.5. Instead, all vehicles 

produced by these manufacturers on or 

after September 1, 2012 must comply 

with this standard. 

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BILLING CODE 4910–59–C 


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PART 585—PHASE-IN REPORTING 

REQUIREMENTS 

4. The authority citation for part 585 

continues to read as follows: 

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

30117, and 30166; delegation of authority at 

49 CFR 1.50. 

5. Subpart I is added to read as 

follows: 

Sec. 

Subpart I—Electronic Stability Control 

System Phase-in Reporting Requirements 

585.81 Scope. 

585.82 Purpose. 

585.83 Applicability. 

585.84 Definitions. 

585.85 Response to inquiries. 

585.86 Reporting requirements. 

585.87 Records. 

585.88 Petition to extend period to file 

report. 

Subpart I—Electronic Stability Control 

System Phase-in Reporting 

Requirements 

§ 585.81 Scope. 

This subpart establishes requirements 

for manufacturers of passenger cars, 

multipurpose passenger vehicles, 

trucks, and buses with a gross vehicle 

weight rating of 4,536 kilograms (10,000 

pounds) or less to submit a report, and 

maintain records related to the report, 

concerning the number of such vehicles 

that meet the requirements of Standard 

No. 126, Electronic stability control 

systems (49 CFR 571.126). 

§ 585.82 Purpose. 

The purpose of these reporting 

requirements is to assist the National 

Highway Traffic Safety Administration 

in determining whether a manufacturer 

has complied with Standard No. 126 (49 

CFR 571.126). 

§ 585.83 Applicability. 

This subpart applies to manufacturers 

of passenger cars, multipurpose 

passenger vehicles, trucks, and buses 

with a gross vehicle weight rating of 

4,536 kilograms (10,000 pounds) or less. 

However, this subpart does not apply to 

manufacturers whose production 

consists exclusively of vehicles 

manufactured in two or more stages, 

and vehicles that are altered after 

previously having been certified in 

accordance with part 567 of this 

chapter. In addition, this subpart does 

not apply to manufacturers whose 

production of motor vehicles for the 

United States market is less than 5,000 

vehicles in a production year. 

§ 585.84 Definitions. 

For the purposes of this subpart: 

Production year means the 12-month 

period between September 1 of one year 

and August 31 of the following year, 

inclusive. 

§ 585.85 Response to inquiries. 

At any time prior to August 31, 2011, 

each manufacturer must, upon request 

from the Office of Vehicle Safety 

Compliance, provide information 

identifying the vehicles (by make, 

model, and vehicle identification 

number) that have been certified as 

complying with Standard No. 126 (49 

CFR 571.126). The manufacturer’s 

designation of a vehicle as a certified 

vehicle is irrevocable. Upon request, the 

manufacturer also must specify whether 

it intends to utilize carry-forward 

credits, and the vehicles to which those 

credits relate. 

§ 585.86 Reporting requirements. 

(a) General reporting requirements. 

Within 60 days after the end of the 

production years ending August 31, 

2009, August 31, 2010, and August 31, 

2011, each manufacturer must submit a 

report to the National Highway Traffic 

Safety Administration concerning its 

compliance with Standard No. 126 (49 

CFR 571.126) for its passenger cars, 

multipurpose passenger vehicles, 

trucks, and buses with a gross vehicle 

weight rating of less than 4,536 

kilograms (10,000 pounds) produced in 

that year. Each report must—

(1) Identify the manufacturer; 

(2) State the full name, title, and 

address of the official responsible for 

preparing the report; 

(3) Identify the production year being 

reported on; 

(4) Contain a statement regarding 

whether or not the manufacturer 

complied with the requirements of 

Standard No. 126 (49 CFR 571.126) for 

the period covered by the report and the 

basis for that statement; 

(5) Provide the information specified 

in paragraph (b) of this section; 

(6) Be written in the English language; 

and 

(7) Be submitted to: Administrator, 

National Highway Traffic Safety 

Administration, 400 Seventh Street, 

SW., Washington, DC 20590. 

(b) Report content. 

(1) Basis for statement of compliance. 

Each manufacturer must provide the 

number of passenger cars, multipurpose 

passenger vehicles, trucks, and buses 

with a gross vehicle weight rating of 

4,536 kilograms (10,000 pounds) or less, 

manufactured for sale in the United 

States for each of the three previous 

production years, or, at the 

manufacturer’s option, for the current 

production year. A new manufacturer 

that has not previously manufactured 

these vehicles for sale in the United 

States must report the number of such 

vehicles manufactured during the 

current production year. 

(2) Production. Each manufacturer 

must report for the production year for 

which the report is filed: The number of 

passenger cars, multipurpose passenger 

vehicles, trucks, and buses with a gross 

vehicle weight rating of 4,536 kilograms 

(10,000 pounds) or less that meet 

Standard No. 126 (49 CFR 571.126). 

(3) Statement regarding compliance. 

Each manufacturer must provide a 

statement regarding whether or not the 

manufacturer complied with the ESC 

requirements as applicable to the period 

covered by the report, and the basis for 

that statement. This statement must 

include an explanation concerning the 

use of any carry-forward credits. 

(4) Vehicles produced by more than 

one manufacturer. Each manufacturer 

whose reporting of information is 

affected by one or more of the express 

written contracts permitted by S8.6.2 of 

Standard No. 126 (49 CFR 571.126) 

must: 

(i) Report the existence of each 

contract, including the names of all 

parties to the contract, and explain how 

the contract affects the report being 

submitted. 

(ii) Report the actual number of 

vehicles covered by each contract. 

§ 585.87 Records. 

Each manufacturer must maintain 

records of the Vehicle Identification 

Number for each vehicle for which 

information is reported under 

§ 585.86(b)(2) until December 31, 2013. 

§ 585.88 Petition to extend period to file 

report. 

A manufacturer may petition for 

extension of time to submit a report 

under this Part. A petition will be 

granted only if the petitioner shows 

good cause for the extension and if the 

extension is consistent with the public 

interest. The petition must be received 

not later than 15 days before expiration 

of the time stated in § 585.86(a). The 

filing of a petition does not 

automatically extend the time for filing 

a report. The petition must be submitted 

to: Administrator, National Highway 

Traffic Safety Administration, 400 

Seventh Street, SW., Washington, DC 

20590. 

Issued: September 7, 2006. 

Stephen R. Kratzke, 

Associate Administrator for Rulemaking. 

[FR Doc. 06–7598 Filed 9–14–06; 10:00 am] 

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