Heavy Vehicle Automatic Emergency Braking; AEB Test Devices

Federal RegisterJul 6, 2023

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DEPARTMENT OF TRANSPORTATION

National Highway Traffic Safety Administration

49 CFR Parts 571 and 596

[Docket No. NHTSA-2023-0023]

RIN 2127-AM36

Federal Motor Carrier Safety Administration

49 CFR Parts 393 and 396

[Docket No. FMCSA-2022-0171]

RIN 2126-AC49

Heavy Vehicle Automatic Emergency Braking; AEB Test Devices

AGENCY:

National Highway Traffic Safety Administration (NHTSA), Federal Motor Carrier Safety Administration (FMCSA), Department of Transportation (DOT).

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

This NPRM proposes to adopt a new Federal Motor Vehicle Safety Standard (FMVSS) to require automatic emergency braking (AEB) systems on heavy vehicles,

i.e.,

vehicles with a gross vehicle weight rating greater than 4,536 kilograms (10,000 pounds). This notice also proposes to amend FMVSS No. 136 to require nearly all heavy vehicles to have an electronic stability control system that meets the equipment requirements, general system operational capability requirements, and malfunction detection requirements of FMVSS No. 136. An AEB system uses multiple sensor technologies and sub-systems that work together to sense when the vehicle is in a crash imminent situation and automatically applies the vehicle brakes if the driver has not done so or automatically applies more braking force to supplement the driver's applied braking. This NPRM follows NHTSA's 2015 grant of a petition for rulemaking from the Truck Safety Coalition, the Center for Auto Safety, Advocates for Highway and Auto Safety and Road Safe America, requesting that NHTSA establish a safety standard to require AEB on certain heavy vehicles. This NPRM also responds to a mandate under the Bipartisan Infrastructure Law, as enacted as the Infrastructure Investment and Jobs Act, directing the Department to prescribe an FMVSS that requires heavy commercial vehicles with FMVSS-required electronic stability control systems to be equipped with an AEB system, and also promotes DOT's January 2022 National Roadway Safety Strategy to initiate a rulemaking to require AEB on heavy trucks. This NPRM also proposes Federal Motor Carrier Safety Regulations requiring the electronic stability control and AEB systems to be on during vehicle operation.

DATES:

Comments must be received on or before September 5, 2023.

Proposed compliance dates:

NHTSA proposes a two-tiered phase-in schedule for meeting the proposed standard. For vehicles currently subject to FMVSS No. 136, “Electronic stability control systems for heavy vehicles,” any vehicle manufactured on or after the first September 1 that is three years after the date of publication of the final rule would be required to meet the proposed heavy vehicle AEB standard. For vehicles with a gross vehicle weight rating greater than 4,536 kilograms (10,000 pounds) not currently subject to FMVSS No. 136, any vehicle manufactured on or after the first September 1 that is four years after the date of publication of the final rule would be required to meet the proposed AEB requirements and the proposed amendments to the ESC requirements. Small-volume manufacturers, final-stage manufacturers, and alterers would be provided an additional year to comply with this proposal beyond the dates identified above.

FMCSA proposes that vehicles currently subject to FMVSS No. 136 would be required to comply with FMCSA's proposed ESC regulation on the final rule's effective date. Vehicles with a GVWR greater than 4,536 kilograms (10,000 pounds) not currently subject to FMVSS No. 136 would be required to meet the proposed ESC regulation on or after the first September 1 that is five years after the date of publication of the final rule.

FMCSA proposes that, for vehicles currently subject to FMVSS No. 136, any vehicle manufactured on or after the first September 1 that is three years after the date of publication of the final rule would be required to meet FMCSA's proposed AEB regulation. FMCSA proposes that vehicles with a gross vehicle weight rating greater than 4,536 kilograms (10,000 pounds) not currently subject to FMVSS No. 136 and vehicles supplied to motor carriers by small-volume manufacturers, final-stage manufacturers, and alterers would be required to meet the proposed AEB regulation on or after the first September 1 that is five years after the date of publication of the final rule.

This proposed implementation timeframe simplifies FMCSR training and enforcement because the Agency expects a large number of final stage manufacturers supplying vehicles to motor carriers in the category of vehicles with a gross vehicle weight rating greater than 4,536 kilograms (10,000 pounds).

FMCSA's phase-in schedule would require the ESC and AEB systems to be inspected and maintained in accordance with § 396.3.

Early compliance is permitted but optional.

ADDRESSES:

You may submit comments to the docket number identified in the heading of this document by any of the following methods:

•

Federal eRulemaking Portal:

Go to

https://www.regulations.gov.

Follow the online instructions for submitting comments.

•

Mail:

Docket Management Facility, M-30, U.S. Department of Transportation, West Building, Ground Floor, Rm. W12-140, 1200 New Jersey Avenue SE, Washington, DC 20590.

•

Hand Delivery or Courier:

West Building, Ground Floor, Room W12-140, 1200 New Jersey Avenue SE, between 9 a.m. and 5 p.m. Eastern Time, Monday through Friday, except Federal holidays. To be sure someone is there to help you, please call 202-366-9332 before coming.

•

Fax:

202-493-2251.

Regardless of how you submit your comments, please provide the docket number of this document.

Instructions:

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

https://www.regulations.gov

, including any personal information provided.

Privacy Act:

In accordance with 5 U.S.C. 553(c), DOT solicits comments from the public to better inform its decision-making process. DOT posts these comments, without edit, including any personal information the commenter provides, to

https://www.regulations.gov

, as described in the system of records notice (DOT/ALL-14 FDMS), which can be reviewed at

https://www.transportation.gov/privacy.

In order to facilitate comment tracking and response, the agency encourages commenters to provide their name, or the name of their organization; however, submission of names is completely optional. Whether or not commenters identify themselves, all timely comments will be fully considered.

Docket:

For access to the docket to read background documents or

comments received, go to

https://www.regulations.gov

, or the street address listed above. To be sure someone is there to help you, please call 202-366-9322 before coming. Follow the online instructions for accessing the dockets.

FOR FURTHER INFORMATION CONTACT:

NHTSA: For non-legal issues: Hisham Mohamed, Office of Crash Avoidance Standards (telephone: 202-366-0307). For legal issues: David Jasinski, Office of the Chief Counsel (telephone: 202-366-2992, fax: 202-366-3820). The mailing address for these officials is: National Highway Traffic Safety Administration, 1200 New Jersey Avenue SE, Washington, DC 20590. FMCSA: For FMCSA issues: David Sutula, Office of Vehicle and Roadside Operations Division (telephone: 202-366-9209). The mailing address for this official is: Federal Motor Carrier Safety Administration, 1200 New Jersey Avenue SE, Washington, DC 20590.

SUPPLEMENTARY INFORMATION:

Table of Contents

I. Executive Summary

II. Safety Problem

III. Efforts To Promote AEB Deployment in Heavy Vehicles

A. NHTSA's Foundational AEB Research

B. NHTSA's 2015 Grant of a Petition for Rulemaking

C. Congressional Interest

1. MAP-21

2. Bipartisan Infrastructure Law

D. IIHS Effectiveness Study

E. DOT's National Roadway Safety Strategy (January 2022)

F. National Transportation Safety Board Recommendations

G. FMCSA Initiatives

IV. NHTSA and FMCSA Research and Testing

A. NHTSA-Sponsored Research

1. 2012 Study on Effectiveness of FCW and AEB

2. 2016 Field Study

3. 2017 Target Population Study

4. 2018 Cost and Weight Analysis

B. VRTC Research Report Summaries and Test Track Data

1. Relevance of Research Efforts on AEB for Light Vehicles

2. Phase I Testing of Class 8 Truck-Tractors and Motorcoach

3. Phase II Testing of Class 8 Truck-Tractors

4. NHTSA's 2018 Heavy Vehicle AEB Testing

5. NHTSA's Research Test Track Procedures

6. 2021 VRTC Testing

C. NHTSA Field Study of a New Generation Heavy Vehicle AEB System

D. FMCSA-Sponsored Research

V. Need for This Proposed Rule and Guiding Principles

A. Estimating AEB System Effectiveness

B. AEB Performance Over a Range of Speeds Is Necessary and Practicable

C. Market Penetration Varies Significantly Among Classes of Heavy Vehicles

D. This NPRM Would Compel Improvements in AEB

E. BIL Section 23010(b)(2)(B)

F. Vehicles Excluded From Braking Requirements

VI. Heavy Vehicles Not Currently Subject to ESC Requirements

A. AEB and ESC Are Less Available on These Vehicles

B. This NPRM Proposes To Require ESC

C. BIL Section 23010(d)

D. Multi-Stage Vehicle Manufacturers and Alterers

VII. Proposed Performance Requirements

A. Proposed Requirements When Approaching a Lead Vehicle

1. Automatic Emergency Brake Application Requirements

2. Forward Collision Warning Requirement

i. FCW Modalities

ii. FCW Auditory Signal Characteristics

iii. FCW Visual Signal Characteristics

iv. FCW Haptic Signal Discussion

3. Performance Test Requirements

4. Performance Test Scenarios

i. Stopped Lead Vehicle

ii. Slower-Moving Lead Vehicle

iii. Decelerating Lead Vehicle

5. Parameters for Vehicle Tests

i. Vehicle Speed Parameters

ii. Headway

iii. Lead Vehicle Deceleration Parameter

6. Manual Brake Application in the Subject Vehicle

B. Conditions for Vehicle Tests

1. Environmental Conditions

2. Road Service Conditions

3. Subject Vehicle Conditions

C. Proposed Requirements for False Activation

1. No Automatic Braking Requirement

2. Vehicle Test Scenarios

i. Steel Trench Plate

ii. Pass-Through

D. Conditions for False Activation Tests

E. Potential Alternatives to False Activation Tests

F. Proposed Requirements for Malfunction Indication

G. Deactivation Switch

H. System Documentation

I. ESC Performance Test

J. Severability

VIII. Vehicle Test Device

A. Description and Development

B. Specifications

C. Alternatives Considered

IX. Proposed Compliance Date Schedule

X. Retrofitting

XI. Summary of Estimated Effectiveness, Cost, Benefits, and Comparison of Regulatory Alternatives

A. Crash Problem

B. AEB System Effectiveness

C. ESC System Effectiveness

D. Avoided Crashes and Related Benefits

E. Technology Costs

F. Monetized Benefits

G. Alternatives

XII. Regulatory Notices and Analyses

XIII. Public Participation

XIV. Appendices to the Preamble

A. Description of Technologies

B. International Regulatory Requirements and Other Standards

Abbreviations Frequently Used in This Document

The following table is provided for the convenience of readers for illustration purposes only.

Table 1—Abbreviations

Abbreviation

Full term

Notes

ABS

Antilock Braking System

Automatically controls the degree of longitudinal wheel slip during braking to prevent wheel lock and minimize skidding by sensing the rate of angular rotation of each wheel and modulating the braking force at the wheels to keep the wheels from slipping.

AEB

Automatic Emergency Braking

Applies a vehicle's brakes automatically to avoid or mitigate an impending forward crash.

CIB

Crash Imminent Braking

Applies automatic braking when forward-looking sensors indicate a crash is imminent and the driver has not applied the brakes.

CMV

Commercial Motor Vehicle

Has the meaning given the term in 49 U.S.C. 31101.

CRSS

Crash Report Sampling System

A sample of police-reported crashes involving all types of motor vehicles, pedestrians, and cyclists, ranging from property-damage-only crashes to those that result in fatalities.

DBS

Dynamic Brake Support

Supplements the driver's application of the brake pedal with additional braking when sensors determine the driver-applied braking is insufficient to avoid an imminent crash.

ESC

Electronic Stability Control

Able to determine intended steering direction (steering wheel angle sensor), compare it to the actual vehicle direction, and then modulate braking forces at each wheel to induce a counter yaw when the vehicle starts to lose lateral stability.

FARS

Fatality Analysis Reporting System

A nationwide census providing annual data regarding fatal injuries suffered in motor vehicle crashes.

FCW

Forward Collision Warning

An auditory and visual warning provided to the vehicle operator by the AEB system that is designed to induce an immediate forward crash avoidance response by the vehicle operator.

FMCSR

Federal Motor Carrier Safety Regulations

49 CFR parts 350-399.

FMVSS

Federal Motor Vehicle Safety Standards

GES

General Estimates System

Data from a nationally representative sample of police reported motor vehicle crashes of all types, from minor to fatal.

GVWR

Gross Vehicle Weight Rating

The value specified by the manufacturer as the maximum design loaded weight of a single vehicle.

BIL

Bipartisan Infrastructure Law

Public Law 117-58 (Nov. 15, 2021).

MAIS

Maximum Abbreviated Injury Scale

A means of describing injury severity based on an ordinal scale. An MAIS 1 injury is a minor injury and an MAIS 5 injury is a critical injury.

MAP-21

The Moving Ahead for Progress in the 21st Century Act

A funding and authorization bill to govern United States Federal surface transportation spending. It was enacted into law on July 6, 2012.

NCAP

New Car Assessment Program

PDO

Property-damage-only

A police-reported crash involving a motor vehicle in transport on a trafficway in which no one involved in the crash suffered any injuries.

PDOV

Property-Damage-Only-Vehicles

Damaged vehicles involved in property-damage-only crashes.

TTC

Time to collision

The theoretical time, given the current speed of the vehicles, after which a rear-end collision with the lead vehicle would occur if no corrective action was taken.

VRTC

Vehicle Research and Test Center

NHTSA's in-house laboratory.

VTD

Vehicle Test Device

A test device used to test AEB system performance.

I. Executive Summary

There were 38,824 people killed in motor vehicle crashes on U.S. roadways in 2020 and early estimates put the number of fatalities at 42,915 for 2021.

The Department established the National Roadway Safety Strategy in January 2022 to address this rising number of transportation deaths occurring on this country's streets, roads, and highways.

This NPRM takes a crucial step in implementing this strategy by proposing to adopt a new Federal motor vehicle safety standard (FMVSS) that would require heavy vehicles to have automatic emergency braking (AEB) systems that mitigate the frequency and severity of rear-end collisions with vehicles.

https://crashstats.nhtsa.dot.gov/Api/Public/ViewPublication/813266, https://crashstats.nhtsa.dot.gov/Api/Public/ViewPublication/813283, https://www.nhtsa.gov/press-releases/early-estimate-2021-traffic-fatalities#:~:text=Preliminary%20data%20reported%20by%20the,from%201.34%20fatalities%20in%202020.

https://www.transportation.gov/sites/dot.gov/files/2022-01/USDOT_National_Roadway_Safety_Strategy_0.pdf.

Last accessed August 23, 2022.

The crash problem addressed by heavy vehicle AEB is substantial, as are the safety benefits to be gained. This NPRM addresses lead vehicle rear-end, rollover, and loss of control crashes, and their associated fatalities, injuries, and property damage. The NPRM also proposes new Federal Motor Carrier Safety Regulations requiring the electronic stability control and AEB systems to be on during vehicle operation. Considering the effectiveness of AEB and electronic stability control technology (ESC) at avoiding these crashes, the proposed rule would conservatively prevent an estimated 19,118 crashes, save 155 lives, and reduce 8,814 non-fatal injuries annually once all vehicles covered in this rule are equipped with AEB and ESC. In addition, it would eliminate 24,828 property-damage-only crashes annually.

In this NPRM, the term “heavy vehicles” refers to vehicles with a gross vehicle weight rating (GVWR) greater than 4,536 kilograms (10,000 pounds). For application of the FMVSS, it is often necessary to further categorize these heavy vehicles, as the FMVSS must be appropriate for the particular type of motor vehicle for which they are prescribed.

3 4

Certain vehicles have common characteristics relevant to the application of AEB, and categorizing those vehicles accordingly allows for useful analyses, proposals, or other considerations that are particularly appropriate for the vehicle group and application of the safety standards.

As required by 49 U.S.C 30111(b)(3), NHTSA shall consider whether a proposed standard is reasonable, practicable, and appropriate for the particular type of motor vehicle or motor vehicle equipment for which it is prescribed.

This NPRM excludes heavy trailers because they typically do not have braking components necessary for AEB.

One useful way to categorize vehicles further is by GVWR. This NPRM uses vehicle class numbers designed by NHTSA in 49 CFR 565, “Vehicle identification number requirements,” and the Federal Highway Administration that are based on GVWR.

These class numbers, shown in Table 2 below, are widely used by industry and States in categorizing vehicles. In this NPRM, “heavy vehicle” and “class 3 through 8” both refer to all vehicles with a GVWR greater than 4,536 kg (10,000 lbs.). The term “class 3 through 6” refers to vehicles with a GVWR greater than 4,536 kg (10,000 lbs.) and up to 11,793 kg (26,000 lbs.), while the term “class 7 to 8” refers to vehicles with a GVWR greater than 11,793 kg (26,000 lbs.).

See

https://ops.fhwa.dot.gov/publications/fhwahop10014/s5.htm#f21

(Last viewed on May 5, 2022).

Table 2—Vehicle Class by GVWR

Vehicle class

GVWR

Not greater than 2,722 kg (6,000 lbs.).

Greater than 2,722 kg (6,000 lbs.) and up to 3,856 kg (8,500 lbs.).

Greater than 3,856 kg (8,500 lbs.) and up to 4,536 kg (10,000 lbs.).

Greater than 4,536 kg (10,000 lbs.) and up to 6,350 kg (14,000 lbs.).

Greater than 6,350 kg (14,000 lbs.) and up to 7,257 kg (16,000 lbs.).

Greater than 7,257 kg (16,000 lbs.) and up to 8,845 kg (19,500 lbs.).

Greater than 8,845 kg (19,500 lbs.) and up to 11,793 kg (26,000 lbs.).

Greater than 11,793 kg (26,000 lbs.) and up to 14,969 kg (33,000 lbs.).

Greater than 14,969 kg (33,000 lbs.).

NHTSA and FMCSA have jointly developed this NPRM. Both agencies will have complementary standards that respond to mandates in Section 23010 of the Bipartisan Infrastructure Law (BIL), as enacted as the Infrastructure Investment and Jobs Act. Section 23010(b) requires the Secretary to prescribe an FMVSS that requires any commercial motor vehicle subject to FMVSS No. 136, “Electronic stability control systems for heavy vehicles,” to be equipped with an AEB system meeting performance requirements established in the new FMVSS not later than two years after enactment. Section 23010(c) requires the Secretary to prescribe a Federal Motor Carrier Safety Regulation (FMCSR) that requires, for commercial motor vehicles subject to FMVSS No. 136, that an AEB system installed pursuant to the new Federal motor vehicle safety standard must be used at any time during which the commercial motor vehicle is in operation. This NPRM sets forth NHTSA's proposed FMVSS and FMCSA's proposed FMCSR issued pursuant to these provisions of the BIL. In order to provide the benefits of AEB to a greater number of vehicles, this proposal would also require that many heavy vehicles not currently subject to FMVSS No. 136, including vehicles in classes 3 through 6, be equipped with ESC and AEB systems under the authority provided in the Motor Vehicle Safety Act. Pursuant to section 23010(d) of the BIL, NHTSA seeks public comment on this proposal.

NHTSA's Statutory Authority

NHTSA is proposing this NPRM under the National Traffic and Motor Vehicle Safety Act (“Motor Vehicle Safety Act”) and in response to the Bipartisan Infrastructure Law. 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. “Motor vehicle safety” is defined in the Motor Vehicle Safety Act as “the performance of a motor vehicle or motor vehicle equipment in a way that protects the public against unreasonable risk of accidents occurring because of the design, construction, or performance of a motor vehicle, and against unreasonable risk of death or injury in a crash, and includes nonoperational safety of a motor vehicle.” “Motor vehicle safety standard” means a minimum performance standard for motor vehicles or motor vehicle equipment. When prescribing such standards, the Secretary must consider all relevant, available motor vehicle safety information. The Secretary must also consider whether a proposed standard is reasonable, practicable, and appropriate for the types of motor vehicles or motor vehicle equipment for which it is prescribed and the extent to which the standard will further the statutory purpose of reducing traffic accidents and associated deaths. The responsibility for promulgation of Federal motor vehicle safety standards is delegated to NHTSA.

In developing this NPRM, NHTSA carefully considered these statutory requirements, and relevant Executive Orders, Departmental Orders, and administrative laws and procedures. NHTSA is also issuing this NPRM in response to the Bipartisan Infrastructure Law. Section 23010 of BIL

requires the Secretary to prescribe a Federal motor vehicle safety standard to require all commercial motor vehicles subject to a particular brake system standard to be equipped with an AEB system meeting established performance requirements. BIL directs the Secretary to prescribe the standard not later than two years after the date of enactment of the Act.

Public Law 117-58, (Nov. 15, 2021).

FMCSA's Statutory Authority

For purposes of this NPRM, FMCSA's authority is found in the Motor Carrier Act of 1935 (1935 Act, 49 U.S.C. 31502) and the Motor Carrier Safety Act of 1984 (1984 Act, 49 U.S.C. 31132

et seq.

), both as amended. The authorities assigned to the Secretary in these two acts are delegated to the FMCSA Administrator in 49 CFR 1.87(i) and (f), respectively. In addition, section 23010(c) of the BIL, Public Law 117-58, 135 Stat. 429, 766-767, Nov. 15, 2021, requires FMCSA to adopt an AEB regulation consistent with the companion NHTSA AEB regulation.

The 1935 Act authorizes the DOT to “prescribe requirements for—(1) qualifications and maximum hours of service of employees of and safety of operation and equipment of a motor carrier; and (2) qualifications and maximum hours of service of employees of, and standards of equipment of, a motor private carrier, when needed to promote safety of operations” (49 U.S.C. 31502(b)). FMCSA's proposed ESC and AEB regulations, which incorporate the ESC and AEB requirements of the NHTSA rule, will require most motor carriers to maintain and use the ESC and AEB systems required by the corresponding NHTSA regulations to promote safety of operations.

The 1984 Act confers on DOT the authority to regulate drivers, motor carriers, and vehicle equipment. “At a minimum, the regulations shall ensure that—(1) commercial motor vehicles are maintained, equipped, loaded, and operated safely; (2) the responsibilities imposed on operators of commercial motor vehicles do not impair their ability to operate the vehicles safely; (3) the physical condition of operators of commercial motor vehicles is adequate to enable them to operate the vehicles safely; (4) the operation of commercial motor vehicles does not have a deleterious effect on the physical condition of the operators; and (5) an operator of a commercial motor vehicle is not coerced by a motor carrier, shipper, receiver, or transportation intermediary to operate a commercial motor vehicle in violation of a regulation promulgated under this section, or chapter 51 or chapter 313 of this title” (49 U.S.C. 31136(a)(1)-(5)).

FMCSA's proposed rule will help to ensure that commercial motor vehicles (CMVs) equipped with the ESC and AEB systems mandated by NHTSA are maintained and operated safely, as required by 49 U.S.C. 31136(a)(1). While the FMCSA proposal does not explicitly address the remaining provisions of section 31136, it will enhance the ability of drivers to operate safely, consistent with 49 U.S.C. 31136(a)(2)-(4).

Section 23010(c) of BIL requires FMCSA to prescribe a regulation under 49 U.S.C. 31136 that requires that an automatic emergency braking system installed in a commercial motor vehicle manufactured after the effective date of the NHTSA standard that is in operation on or after that date and is subject to 49 CFR 571.136 be used at any time during which the commercial motor vehicle is in operation” (135 Stat. 767). Consistent with the BIL mandate, part of FMCSA's proposal would require that motor carriers operating CMVs manufactured subject to FMVSS No. 136 maintain and use the required AEB devices as prescribed by NHTSA whenever the CMV is operating.

AEB and ESC Systems

An AEB system employs multiple sensor technologies and sub-systems that work together to sense when a vehicle is in a crash imminent situation with a lead vehicle and, when necessary, automatically apply the vehicle brakes if the driver has not done so, or apply the brakes to supplement the driver's applied braking. Current systems use radar and camera-based sensors or combinations thereof. AEB builds upon older forward collision warning-only systems. An FCW-only system provides an alert to a driver of an impending rear-end collision with a lead vehicle to induce the driver to take action to avoid the crash but does not automatically apply the brakes. This proposal would require both FCW and AEB systems. For simplicity, when referring to AEB systems in general, this proposal is referring to both FCW and AEB unless the context suggests otherwise.

This proposal follows up on NHTSA's October 16, 2015 notice granting a petition for rulemaking submitted by the Truck Safety Coalition, the Center for Auto Safety, Advocates for Highway and Auto Safety, and Road Safe America.

The petitioners requested that NHTSA establish a safety standard to require automatic forward collision avoidance and mitigation systems on heavy vehicles. This rulemaking also addresses recommendations made to NHTSA by the National Transportation Safety Board.

80 FR 62487.

The safety problem addressed by AEB is substantial. An annualized average of 2017 to 2019 data from NHTSA's Fatality Analysis Reporting System (FARS) and the Crash Report Sampling System (CRSS) shows that heavy vehicles are involved in around 60,000 rear-end crashes in which the heavy vehicle was the striking vehicle annually, which represents 11 percent of all crashes involving heavy vehicles.

These rear-end crashes resulted in 388 fatalities annually, which comprises 7.4 percent of all fatalities in heavy vehicle crashes. These crashes resulted in approximately 30,000 injuries annually, or 14.4 percent of all injuries in heavy vehicle crashes, and 84,000 damaged vehicles with no injuries or fatalities.

These rear-end crashes are cases where the heavy vehicle was the striking vehicle.

Considering vehicle size, approximately half of the rear-end crashes, injuries, and fatalities resulting from rear-end crashes where the heavy vehicle was the striking vehicle involved vehicles with a gross vehicle weight rating above 4,536 kilograms (10,000 pounds) up to 11,793 kilograms (26,000 pounds). Similarly, half of all rear-end crashes and the fatalities and injuries resulting from those crashes where the heavy vehicle was the striking vehicle involved vehicles with a gross vehicle weight rating of greater than 11.793 kilograms (26,000 pounds).

The speed of the striking vehicle is an important factor in the severity of a crash. For example, in approximately 53 percent of crashes, the striking vehicle was traveling at or under 30 mph (47 km/h). Those crashes, though, were responsible for only approximately 1 percent of fatalities. In contrast, in approximately 17 percent of crashes, the striking vehicle was traveling over 55 mph (89 km/h). Those crashes resulted in 89 percent of the fatalities from rear-end crashes involving heavy vehicles. While the majority of crashes occur at low speeds, the overwhelming majority of fatalities result from high-speed crashes. For AEB systems to address this safety problem, they must function at both low and high speeds.

NHTSA has been studying AEB technologies since their conception over 15 years ago. NHTSA and FMCSA have recognized the potential of heavy vehicle AEB for many years and continued to research this technology as it evolved from early generations to its current state. As part of NHTSA's efforts to better understand these new collision prevention technologies, NHTSA sponsored and conducted numerous research projects, including ones focused on AEB and FCW for heavy trucks. NHTSA conducted testing at its in-house testing facility, the Vehicle Research and Test Center, to examine the effectiveness of AEB in different crash scenarios and speeds. NHTSA and FMCSA have also sponsored or conducted projects with a specific focus on the heavy vehicle rear-end crash problem.

International standards for the regulation of AEB systems on heavy vehicles exist and are under development. The European Union and Asian countries have either already adopted or are considering AEB regulations for heavy vehicles. More information can be found in Appendix A of this document.

In 2016, NHTSA published its first report of track testing of heavy vehicles equipped with AEB systems. NHTSA used its light vehicle test procedures, similar to those used in NHTSA's New Car Assessment Program,

as a framework to adapt for use on heavy vehicles. These scenarios included a stopped lead vehicle scenario, a slower moving lead vehicle scenario, a decelerating lead vehicle scenario, and a false positive scenario that consisted of driving over a steel trench plate. NHTSA's initial testing of AEB systems focused on vehicles equipped with ESC—primarily Class 8 truck tractors and motorcoaches. Adjustments had to be made to the scenarios to account for the greater stopping distances of heavy vehicles compared to light vehicles and to the surrogate vehicle and towing device to ensure that the systems performed as they would on the road. Testing of early heavy vehicle systems indicated that vehicles did not automatically brake when encountering a stopped lead vehicle. The false positive test also resulted in FCW alerts, but no automatic braking.

NHTSA's New Car Assessment Program (NCAP) provides comparative information on the safety performance of new vehicles to assist consumers with vehicle purchasing decisions and to encourage safety improvements.

Later testing was intended to evaluate the evolution of AEB systems, to further refine the test procedures, and to test other vehicle types such as single-unit trucks and class 3 through 6 vehicles. Newer FCW and AEB systems on heavy vehicles generally performed better than older versions. Testing of these updated systems exhibited less severe rear-end collisions through velocity reductions before a collision or avoided contact with a lead vehicle entirely. The refined test procedures addressed previous

issues with timing, range parameters, and the vehicle test device.

NHTSA's most recent testing of a 2021 Freightliner Cascadia, a class 8 truck tractor, indicated that the AEB system was able to prevent a collision with a lead vehicle at speeds between 40 km/h and 85 km/h. Collisions occurred with the lead vehicle at lower speeds, although significant speed reductions were still achieved. This suggests that collision avoidance at lower speed cannot necessarily be extrapolated to performance outcomes at higher speed and may depend on the specific ways AEB systems may be programmed. It also indicates that AEB systems that prevent collisions at higher speeds are practicable.

NHTSA and FMCSA studies have also examined system availability across all types of heavy vehicles. Across larger (class 7 and 8) air braked truck tractors and motorcoaches, AEB systems are widely available. A market analysis of class 3 through 6 heavy vehicles showed that nearly all manufacturers had at least one vehicle model within each class available with AEB. Two manufacturers had AEB advertised as standard equipment on at least one model. All vehicles that were offered with AEB systems were also equipped with ESC systems. A few models that offered FCW-only systems (not capable of automatic brake application) did so without also having ESC.

Based on these factors, and consistent with the Motor Vehicle Safety Act and the BIL, NHTSA is proposing a new FMVSS that would require nearly all heavy vehicles to be equipped with AEB systems.

Furthermore, FMCSA is proposing that all commercial vehicles equipped with ESC and AEB systems required by NHTSA's proposed rule be used any time the commercial vehicle is in operation. NHTSA is further proposing minimum performance criteria for AEB systems to meet the need for safety. These performance criteria would ensure that AEB systems function at a wide range of speeds that address the safety problem associated with rear-end crashes, injuries, and fatalities.

The vehicles excluded from this proposal include trailers, which by definition, are towed by other vehicles, and vehicles already excluded from NHTSA's braking requirements. For details, see section V.F.

Based on NHTSA's survey of publicly available data on ESC and AEB system availability, all manufacturers that have equipped vehicles with AEB systems (other than FCW-only systems) have done so only if the vehicle is also equipped with an ESC system. Furthermore, NHTSA has consulted with two AEB system manufacturers for heavy vehicles and both indicated that they would equip vehicles with AEB only if they were also equipped with ESC.

An ESC system provides stability under braking by using differential braking and engine torque reduction to reduce lateral instability that could induce rollover or loss of directional control. An ABS system also provides lateral stability under braking. ABS systems are currently required on all vehicles subject to this proposal under FMVSS Nos. 105 and 121. However, the absence of any AEB systems available without ESC leads NHTSA to believe that manufacturers have identified scenarios in which the operation of an AEB system without ESC may have adverse safety effects that are not adequately addressed by ABS systems alone.

On September 29, 2021, NHTSA met with Daimler Truck North America (DTNA) and on October 22, 2021, NHTSA met with Bendix to discuss the AEB systems of heavy vehicles.

Summary of the Proposal

NHTSA has tentatively concluded based upon this information that a safety need exists for an ESC system to be installed on a vehicle equipped with AEB. Consequently, this proposal also requires nearly all heavy vehicles to be equipped with an ESC system.

Even separate from the benefits of AEB, the safety problem related to the vehicles addressed by the FMVSS No. 136 amendments is also substantial. Class 3 through 6 heavy vehicles are involved in approximately 17,000 rollover and loss of control crashes annually. These crashes resulted in 178 fatalities annually, approximately 4,000 non-fatal injuries, and 13,000 damaged vehicles. Currently, pursuant to FMVSS No. 136, only class 7 and 8 truck tractors and certain large buses are required to have ESC systems. FMVSS No. 136 includes both vehicle equipment requirements and performance requirements. This proposal would amend FMVSS No. 136 to require nearly all heavy vehicles to have an ESC system that meets the equipment requirements, the general system operational capability requirements, and malfunction detection requirements of FMVSS No. 136. It would not, as proposed, require vehicles not currently required to have ESC systems to meet any test track performance requirements for ESC systems, though the agency does request comment on whether to include a performance test and, if so, what that test should be. In designing any potential test, NHTSA wishes to remain conscious of the potential testing burden on small businesses and the multi-stage vehicle manufacturers.

The vehicles excluded from the proposed ESC requirements are the same vehicles excluded from the proposed AEB requirements.

The proposed standard includes certain requirements for AEB systems. First, vehicles would be required to provide the driver with a forward collision warning at any forward speed greater than 10 km/h (6.2 mph). NHTSA is proposing that the forward collision warning be auditory and visual with limited specifications for each of the warning modalities. NHTSA has tentatively concluded that no further specification of the warning is necessary.

Second, vehicles would be required to have an AEB system that applies the service brakes automatically at any forward speed greater than 10 km/h (6.2 mph) when a collision with a lead vehicle is imminent. This requirement serves to ensure that AEB systems operate at all speeds above 10 km/h, even if they are above the speeds tested by NHTSA. This requirement also assures at least some level of AEB system performance in rear-end crashes other than those for which NHTSA has test procedures.

Third, the AEB system would be required to prevent the vehicle from colliding with a lead vehicle when tested according to the proposed standard's test procedures. Vehicles with AEB systems meeting the proposed standard would have to automatically activate the braking system when they encounter a stopped lead vehicle, a slower moving lead vehicle, or a decelerating lead vehicle.

The proposed requirements also include two tests to ensure that the AEB system does not inappropriately activate when no collision is actually imminent. These false positive tests provide some assurance that an AEB system is capable of differentiating between an actual imminent collision and a non-threat. While these tests are not comprehensive, they establish a minimum performance for non-activation of AEB systems. The two scenarios NHTSA proposes to test are driving over a steel trench plate and driving between two parked vehicles.

The final proposed requirement for AEB systems is that they be capable of detecting a system malfunction and notify the driver of any malfunction that causes the AEB system not to operate. This proposed requirement would include any malfunction solely attributable to sensor obstruction, such as by accumulated snow or debris, dense fog, or sunlight glare. The malfunction telltale must remain active as long as the malfunction exists, and

the vehicle's starting system is on. The proposal does not include any specifications for the form of this notification to the driver.

The NPRM also includes proposed test procedures. In this NPRM, the heavy vehicle being evaluated with AEB is referred to as the “subject vehicle.” Other vehicles involved in the test are referred to as “vehicle test devices,” (VTDs) and a specific type of VTD called the “lead vehicle” refers to a vehicle which is ahead in the same lane, in the path of the moving subject vehicle. To ensure repeatable test conduct that reflects how a subject vehicle might respond in the real world, this proposal includes broad specifications for a vehicle test device to be used as a lead vehicle or principal other vehicle during testing. NHTSA is proposing that the vehicle test device is based on the specifications in the International Organization for Standardization (ISO) standard 19206-3:2021.

The vehicle test device is a tool that NHTSA would use in the agency's compliance tests to measure the performance of automatic emergency braking systems required by the FMVSS. For its research testing, NHTSA has been using a full-size surrogate vehicle, the Global Vehicle Target (GVT). The GVT falls within the specifications of ISO 19206-3:2021. These specifications include specifications for the dimensions, color and reflectivity, and the radar cross section of a vehicle test device that ensure it appears like a real vehicle to vehicle sensors.

ISO 19206-3:2021, “Road vehicles—Test devices for target vehicles, vulnerable road users and other objects, for assessment of active safety functions—Part 3: Requirements for passenger vehicle 3D targets.”

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

May 2021.

NHTSA has included three test scenarios in this proposed rule for AEB when approaching a lead vehicle—a stopped lead vehicle, a slower moving lead vehicle, and a decelerating lead vehicle. The stopped lead vehicle scenario consists of the subject vehicle—that is, the vehicle being tested—traveling straight at a constant speed approaching a stopped lead vehicle in the center of its path. To satisfy the proposed performance requirement, the subject vehicle must provide an FCW and stop prior to colliding with the lead vehicle. NHTSA proposes to conduct this scenario both with no manual brake application and with manual brake application. Testing with manual brake application is similar to the DBS test procedure that is included in New Car Assessment Program for light vehicles. While DBS is not generally advertised as a feature of AEB systems on air braked vehicles, driver-applied braking should not suppress automatic braking. Testing without manual brake application would be conducted at any constant speed between 10 km/h and 80 km/h. The 80 km/h upper bound of testing reflects safety limitations that would result from any collision resulting from a failure of an AEB system to activate in the testing environment. However, with manual brake application, NHTSA proposes to test vehicles up to 100 km/h. This is possible because the manual brake application ensures at least some level of speed reduction even in a test failure where automatic braking does not occur.

The second test scenario is a slower moving lead vehicle. In this scenario, the subject vehicle is traveling straight at a constant speed, approaching a lead vehicle traveling at a slower speed in the subject vehicle's path. To satisfy the proposed performance test requirement, the subject vehicle must provide an FCW and slow to a speed equal to or below the lead vehicle's speed without colliding with the lead vehicle. As with the stopped lead vehicle test, NHTSA proposes to perform this test with both no manual brake application and manual brake application. The subject vehicle speed without manual brake application would be any constant speed between 40 km/h and 80 km/h, and with manual brake application, testing would be conducted at any constant speed between 70 km/h and 100 km/h. The lead vehicle would travel at 20 km/h in all tests.

The third test scenario is a decelerating lead vehicle. In this scenario, the subject vehicle and lead vehicle are travelling at the same constant speed in the same path and the lead vehicle begins to decelerate. To satisfy the proposed performance test requirement, the subject vehicle must provide an FCW and stop without colliding with the lead vehicle. As with the other AEB tests approaching a lead vehicle, this test is performed both with and without manual brake application. However, the test speeds are the same for both scenarios—either 50 km/h or 80 km/h. The lead vehicle would decelerate with a magnitude between 0.3g and 0.4g and the headway between the vehicles would be any distance between 21 m and 40 m (for 50 km/h tests) or 28 m and 40 m (for 80 km/h tests). The upper bound of the lead vehicle deceleration and the lower bound of the headway were chosen to ensure that the corresponding test scenarios would not require a brake performance beyond what is necessary to satisfy the minimum stopping distance requirements in the FMVSS applicable to brake performance.

This proposal would require that all of the NHTSA AEB requirements be phased in within four years of publication of a final rule. Truck tractors and certain large buses with a GVWR of greater than 11,793 kilograms (26,000 pounds) that are currently subject to FMVSS No. 136 would be required to meet all requirements within three years. Vehicles not currently subject to FMVSS No. 136 would be required to have ESC and AEB systems within four years of publication of a final rule. Small-volume manufacturers, final-stage manufacturers, and alterers would be allowed one additional year (five years total) of lead time.

Consistent with the BIL mandate, FMCSA proposes to require that motor carriers operating CMVs manufactured subject to FMVSS No. 136, maintain and use the required AEB and ESC systems as prescribed by NHTSA for the effective life of the CMV. FMCSA's proposed rule is intended to ensure that commercial motor vehicles equipped with the ESC and AEB systems mandated by NHTSA are maintained and operated safely, as required by 49 U.S.C. 31136(a)(1). While the FMCSA proposal does not explicitly address the remaining provisions of section 31136, it will enhance the ability of drivers to operate safely, consistent with 49 U.S.C. 31136(a)(2)-(4). FMCSA's proposal would require the ESC and AEB systems to be inspected and maintained in accordance with 49 CFR part 396, Inspection, Repair, and Maintenance (§ 396.3).

The proposed requirements would ensure that the benefits resulting from CMVs equipped with ESC and AEB systems are sustained through proper maintenance and operation. The maintenance costs include annual costs required to keep the ESC and AEB systems operative. FMCSA believes the cost of maintaining the ESC and AEB systems over their lifetimes is minimal compared to the cost of equipping trucks with ESC and AEB systems and may be covered by regular annual maintenance.

NHTSA and FMCSA have jointly determined not to propose retrofitting requirements AEB for existing heavy vehicles and ESC for vehicles not currently subject to FMVSS No. 136. For technical reasons, AEB and ESC retrofits are difficult to apply broadly, generically, or inexpensively and thus this NPRM does not propose a retrofit requirement.

NHTSA and FMCSA seek comments and suggestions on any aspect of this

proposal and any alternative requirements to address this safety problem. NHTSA and FMCSA also request comments on the proposed lead time for meeting these requirements, and how the lead time can be structured to maximize the benefits that can be realized most quickly while ensuring that the standard is practicable. Finally, NHTSA and FMCSA seek comment on whether and how this proposal may disproportionately impact small businesses and how NHTSA and FMCSA could revise this proposal to minimize any disproportionate impact.

Benefits and Costs

NHTSA and FMCSA have issued a Preliminary Regulatory Impact Analysis (PRIA) that analyzes the potential impacts of this proposed rule. The PRIA is available in the docket for this NPRM.

This proposed rule is expected to substantially decrease risks associated with rear-end, rollover, and loss of control crashes. The effectiveness of AEB and ESC at avoiding rear-end, rollover, and loss of control crashes is summarized in Table 3 for AEB and Table 4 for ESC.

The PRIA may be obtained by downloading it or by contacting Docket Management at the address or telephone number provided at the beginning of this document.

Table 3—AEB Effectiveness (%) by Vehicle Class Range and Crash Scenario

Vehicle class range

Stopped lead

vehicle

Slower-moving lead

vehicle

Decelerating lead

vehicle

7-8

38.5

49.2

3-6

43.0

47.8

Table 4—ESC Effectiveness (%) by Crash Scenario

Vehicle class range

Rollover

Loss of control

3-6

48.0

14.0

Considering the annual rear-end, rollover, and loss of control crashes, as well as the effectiveness of AEB and ESC at avoiding these crashes, the proposed rule would prevent an estimated 19,118 crashes, save 155 lives, and reduce 8,814 non-fatal injuries, annually. In addition, the proposed rule would eliminate an estimated 24,828 property-damage-only-vehicles (PDOVs), annually. Table 5 shows these estimated benefits also by vehicle class and technology.

Table 5—Estimated Annual Benefits of the Proposed Rule

Crashes

avoided

Fatalities avoided

Non-fatal

injuries

avoided

PDOVs

avoided

By Vehicle Class

Class 7-8

5,691

2,822

7,958

Class 3-6

13,427

115

5,992

16,870

Total

19,118

155

8,814

24,828

By Technology

AEB

16,224

106

8,058

22,713

ESC

2,894

756

2,115

Total

19,118

155

8,814

24,828

There are two potential unintended consequences that cannot be quantified: the impact of false activations on safety and the potential impact of sensor degradation over time on AEB performance. However, the required malfunction indicator combined with FMCSA's proposed AEB and ESC inspection and maintenance requirements would help vehicle operators maintain AEB systems and substantially reduce degradation of AEB sensor performance. We seek comments on these two issues and ask for any data that can help us to quantify these impacts.

The benefits estimate includes assumptions that likely result in the underestimation of the benefits of this proposal because it does not quantify the benefits from crash mitigation. That is, the benefits only reflect those resulting from crashes that are avoided as a result of AEB and ESC. It is likely that AEB will also reduce the severity of crashes that are not prevented. Some of these crashes mitigated may include fatalities and significant injuries that will be prevented or mitigated by AEB. Finally, this NPRM does not quantify any potential benefits that AEB could provide during adverse environmental conditions (night, wet, etc.). While AEB is likely to be effective in many of these crashes, NHTSA is not aware of any data to quantify the performance degradation of AEB in adverse conditions.

The benefits of this proposed rule, monetized and analyzed with the total annual cost, are summarized in Table 6. The total annual cost, considering the implementation of both AEB and ESC technologies proposed in this rule, is

estimated to be $353 million. The proposed rule would generate a net benefit of $2.58 to $1.81 billion, annually under 3 and 7 percent discount rates. The proposed rule would be cost-effective given that the highest estimated net cost per fatal equivalent would be $0.50 million. Maintenance costs are considered de minimis and therefore not included in the cost estimate.

Table 6—Estimated Annual Cost, Monetized Benefits, Cost-Effectiveness, and Net Benefits of the Proposed Rule

[2021 Dollars in millions]

Discount rates

Annual

cost *

Monetized

benefits

Net cost per

fatal equivalent

Net

benefits

3 Percent

$353.3

$2,937.0

−$0.12

$2,583.7

7 Percent

353.3

2,158.0

0.50

1,807.1

* Paid at purchasing; no need to discount.

NHTSA

has issued an NPRM that proposes to adopt an FMVSS for AEB requirements for light vehicles, including pedestrian AEB.

NHTSA notes that it may decide to issue final rules adopting the AEB requirements for light and heavy vehicles in a way that incorporates the AEB requirements into a single Federal motor vehicle safety standard for all vehicle classes.

The negative net cost per fatal equivalent reflects the fact that savings from reducing traffic congestion and damaged property is greater the total compliance costs of the proposed rule.

88 FR 38632 (June 13, 2023).

The following is a brief explanation of terms and technologies used to describe AEB systems. More detailed information can be found in Appendix A to this preamble.

Radar-Based Sensors

Heavy vehicle AEB systems typically employ radar sensors. At its simplest, radar is a time-of-flight sensor that measures the time between when a radio wave is transmitted and its reflection is recorded. This time-of-flight is then used to calculate how far away the object is that caused the reflection. Information about the reflecting object, such as the speed at which it is travelling, can also be determined. Radar units are compact, relatively easy to mount, and do not require a line of sight to function properly. Radar can penetrate most rubbers and plastics, allowing for the units to be installed behind grilles and bumper fascia, increasing mounting options. Radar can detect objects in low-light situations and also works well in environmental conditions like precipitation and fog.

Camera Sensors

Cameras are passive sensors in which optical data are recorded then processed to allow for object detection and classification. Cameras are an important part of many automotive AEB systems, and one or more cameras are typically mounted behind the front windshield and often up high near the rearview mirror. Cameras at this location provide a good view of the road and are protected by the windshield from debris, grease, dirt, and other contaminants that can cover the sensor. Systems that utilize two or more cameras can see stereoscopically, allowing the processing system to determine range information along with detection and classification.

Electronically Modulated Braking Systems

Automatic actuation of the vehicle brakes requires more than just systems to sense when a collision is imminent. In addition to the sensing system, hardware is needed to physically apply the brakes without relying on the driver to apply the brake pedal. AEB leverages two foundational braking technologies, antilock braking systems (ABS) and electronic stability control. AEB uses the hardware equipped for ESC and electronically applies the brakes to avoid certain scenarios where a crash with a vehicle is imminent.

ABS:

Antilock braking systems automatically control the degree of longitudinal wheel slip during braking to prevent wheel lock and minimize skidding by sensing the rate of angular rotation of the wheels and modulating the braking force at the wheels to keep the wheels from locking. Preventing wheel lock, and therefore skidding, greatly increases the controllability of the vehicle during a panic stop. Modern ABS systems have wheel speed sensors, independent brake modulation at each wheel, and can increase or decrease braking pressures as needed. During modulation of a brake application, the ABS system repeatedly relieves and regenerates pressure to quickly release and reapply, or “pulse,” the brake.

ESC:

ESC builds upon the antilock brakes system by adding two sensors, a steering wheel angle sensor and an inertial measurement unit. These sensors allow the ESC controller to determine intended steering direction (steering wheel angle sensor), compare it to the actual vehicle direction, and then modulate braking forces at each wheel to induce a corrective yaw moment when the vehicle starts to lose lateral stability. An ESC system can control the brakes even when the vehicle operator is not pressing the brake pedal.

When an AEB system activates in response to an imminent collision, much of the same or similar hardware from ESC systems is used to automatically control and modulate the brakes. Like ESC, an AEB system includes components that give the vehicle the capacity to automatically apply the brakes even when the vehicle operator is not pressing the brake pedal. To do this in hydraulic brake systems, hydraulic brake pressure is generated by a pump similarly as with ABS. In a pneumatic brake system, the air pressure is already available via the air reservoir and air compressor, and the ESC system must direct this pressure accordingly. Additionally, the safety benefits of ESC enable an AEB system to operate at its potential. Especially under the high-speed, heavy-deceleration emergency braking events that potentially occur during AEB activation, ESC could improve vehicle stability and reduce the propensity for loss of control or rollover crashes that may result from a steering response to an impending rear-end collision.

Forward Collision Warning

A forward collision warning (FCW) system uses the camera and radar sensors described above, and couples them with an alert mechanism. An FCW system can monitor a vehicle's speed, the speed of the vehicle in front of it, and the distance between the two vehicles. If the FCW system determines that the distance from the driver's vehicle to the vehicle in front of it is too short, and the closing velocity between

the two vehicles too high, the system warns the driver of an impending rear-end collision. Warning systems in use today provide drivers with a visual display, such as a light on the instrument panel, an auditory signal (

e.g.,

beeping tone or chime), and/or a haptic signal that provides tactile feedback to the driver (

e.g.,

rapid vibrations of the seat pan or steering wheel or a momentary brake pulse) to alert the driver of an impending crash so they may manually intervene. The alerts provided by FCW systems, even those that include momentary brake pulses, are not intended to provide significant and sustained vehicle deceleration. Rather, the FCW system is intended to inform the driver that they must take corrective action in certain rear-end crash-imminent driving situations.

Automatic Emergency Braking

An automatic emergency braking system automatically applies the brakes to help drivers avoid or mitigate the severity of rear-end crashes. AEB has two primary functions, crash imminent braking (CIB) and a brake support system that supplements a driver's applied braking, which is referred to as dynamic brake support (DBS) in the light vehicle context. CIB systems apply automatic braking when forward-looking sensors indicate a crash is imminent and the driver has not applied the brakes, while supplemental brake support systems use the same forward-looking sensors, but also supplement the driver's application of the brake pedal with enhanced braking when sensors determine the driver-applied braking is insufficient to avoid the imminent crash. This NPRM does not split the terminology of these CIB and supplemental brake support functionalities, and instead considers both functions as part of AEB. The proposed standard includes performance tests that would entail installation of AEB that has both CIB and supplemental brake support functionalities.

“AEB” as Used in This NPRM

As used in this NPRM, when we refer to “AEB,” we mean a system that has: (a) a forward collision warning (FCW) component to alert the driver to an impending collision; (b) a crash imminent braking component (CIB) that automatically applies the vehicle's brakes if the driver does not respond to an imminent crash in the forward direction regardless of whether there's an FCW alert; and, (c) a supplemental brake support component that automatically supplements the driver's brake application if the driver applies insufficient manual braking.

II. Safety Problem

Overview

There were 38,824 people killed in motor vehicle crashes on U.S. roadways in 2020 and 42,939 in 2021.

17 18

The 2021 data are the highest numbers of fatalities since 2005. While the upward trend in fatalities may be related to increases in risky driving behaviors during the COVID-19 pandemic,

NHTSA data from 2010 to 2019 show an increase of approximately 3,000 fatalities since 2010. There has also been an upward trend since 2010 in the total number of motor vehicle crashes, which corresponds to an increase in fatalities, injuries, and property damage. NHTSA uses data from its FARS and the CRSS, to account for and understand motor vehicle crashes.

https://crashstats.nhtsa.dot.gov/Api/Public/ViewPublication/813266;

https://www.nhtsa.gov/press-releases/early-estimate-2021-traffic-fatalities#:~:text=Preliminary%20data%20reported%20by%20the,from%201.34%20fatalities%20in%202020.

https://crashstats.nhtsa.dot.gov/Api/Public/ViewPublication/813435; https://crashstats.nhtsa.dot.gov/Api/Public/ViewPublication/813283; https://www.nhtsa.gov/press-releases/early-estimate-2021-traffic-fatalities#:~:text=Preliminary%20data%20reported%20by%20the,from%201.34%20fatalities%20in%202020.

These behaviors relate to increases in impaired driving, the non-use of seat belts, and speeding.

The Crash Report Sampling System (CRSS) builds on a previous, long-running National Automotive Sampling System General Estimates System (NASS GES). CRSS is a sample of police-reported crashes involving all types of motor vehicles, pedestrians, and cyclists, ranging from property-damage-only crashes to those that result in fatalities. CRSS is used to estimate the overall crash picture, identify highway safety problem areas, measure trends, drive consumer information initiatives, and form the basis for cost and benefit analyses of highway safety initiatives and regulations. FARS contains data on every fatal motor vehicle traffic crash within the 50 States, the District of Columbia, and Puerto Rico. To be included in FARS, a traffic crash must involve a motor vehicle traveling on a public trafficway that results in the death of a vehicle occupant or a nonoccupant within 30 days of the crash.

Rear-End Crashes

As defined in a NHTSA technical manual relating to data entry for FARS and CRSS, rear-end crashes are incidents where the first event is defined as the frontal area of one vehicle striking a vehicle ahead in the same travel lane. In a rear-end crash, as instructed by the FARS/CRSS Coding and Validation Manual, the vehicle ahead is categorized as intending to head either straight, left or right, and is either stopped, travelling at a lower speed, or decelerating.

https://crashstats.nhtsa.dot.gov/Api/Public/ViewPublication/813251

Category II Configuration D. Rear-End.

Heavy Vehicle Rear-End Crashes

On average from 2017 to 2019, there were 6.65 million annual police-reported crashes resulting in 36,888 fatalities. Of the police-reported crashes, approximately 550,000 involved a heavy vehicle (a vehicle with a GVWR greater than 4,536 kg (10,000 pounds)), resulting in 5,255 fatalities.

Thus, heavy vehicle crashes represented 8.3 percent of the total number of crashes and resulted in 14.2 percent of all fatalities. Annually, the entire U.S. fleet traveled a total of 3,237,449 million miles, and 9.3 percent of total vehicle miles traveled were in heavy vehicles.

Data are from 2017-2019 FARS and CRSS crash databases, as discussed in the accompanying PRIA.

See the Traffic Safety Report at

https://crashstats.nhtsa.dot.gov/Api/Public/ViewPublication/813141

(Last viewed September 22, 2022).

A typical heavy vehicle rear-end crash is characterized by a heavy vehicle travelling on a roadway and colliding with another vehicle ahead of it travelling in the same direction, but which is stopped, moving slower, or decelerating, usually within the same lane. While these crashes occur nationwide on all types of roads and in all environments, they overwhelmingly take place on straight roadways (99 percent) and in dry conditions (85 percent). Approximately 60,000 (11 percent of heavy vehicle crashes annually), were rear-end crashes in which the heavy vehicle was the striking vehicle. These rear-end crashes resulted in 388 fatalities annually (7.4 percent of all fatalities in heavy vehicle crashes), approximately 30,000 injuries (14.3 percent of injuries in all heavy vehicle crashes.), and approximately 84,000 damaged vehicles (without injuries or fatalities).

All data in this paragraph are from 2017-2019 FARS and CRSS crash databases, and are discussed in the accompanying PRIA.

The PRIA accompanying this proposal includes a complete review and analysis of the relevant crash data and provides full details about the target population of this NPRM. A summary of the PRIA is contained in section XI. of this proposal.

Rear-End Crashes by Heavy Vehicle Class

Installing AEB on vehicles is related to the installation of ESC on vehicles. ESC is required by FMVSS No. 136 for truck tractors and certain large buses with a GVWR greater than 11,793 kg

(26,000 lbs.). Although the group of heavy vehicles that is not subject to FMVSS No. 136 and the group of heavy vehicles that is subject to FMVSS No. 136 are not solely defined by GVWR range, those not subject to FMVSS No. 136 can be generally characterized as class 3-6 vehicles, while those that are subject to FMVSS No. 136 can be generally characterized as class 7-8 vehicles. Accordingly, NHTSA has further examined rear-end crash data for each of these vehicle class ranges.

The lower weight range of class 3 through 6 includes vehicles such as delivery vans, utility trucks, and smaller buses. Sales data for 2018 and 2019 show that on average 454,692 class 3-6 vehicles per year were sold in the U.S.

Approximately 57 percent of these were class 3 vehicles. Based on crash data, NHTSA determined that class 3-6 vehicles are involved in an annual average of 29,493 rear-end crashes where the heavy vehicle is the striking vehicle. As a result of these crashes, there were 184 fatalities, 14,675 injuries, and 41,285 PDOVs per year on average. A NHTSA study also shows that, according to FARS data, fatalities related to crashes involving these vehicles are on the rise.

In 2015, trucks and buses in this category were involved in 2 percent of all fatal crashes in the U.S., but that increased to 4 percent in 2019.

This information is available in the S&P Global's presentation titled “MHCV Safety Technology Study,” which has been placed in the docket identified in the heading of this NPRM.

Mynatt, M., Zhang, F., Brophy, J., Subramanian, R., Morgan, T. (2022, September). Medium Truck Special Study (Report No. DOT HS 813 371). Washington, DC: National Highway Traffic Safety Administration.

In 2015, 655 of the 32,538 total fatalities involved a class 3-6 truck. In 2019, it increased to 1,301 of the 33,244 total fatalities.

The higher weight range of class 7 and 8 includes vehicles such as larger single-unit trucks, combination tractor-trailers, transit buses, and motorcoaches (GVWR greater than 11,793 kg (26,000 lbs.)).

Sales data for 2018 and 2019 shows that on average 332,558 class 7-8 vehicles per year were sold in the U.S. Approximately 77 percent of these were class 8 vehicles. NHTSA estimates that class 7 and 8 vehicles are involved in 30,416 rear-end crashes where the heavy vehicle is the striking vehicle. As a result of these crashes, there were an annual average of 204 fatalities, 15,117 injuries, and 42,466 PDOVs. As these data indicate, the numbers of crashes, fatalities, injuries, and PDOVs are very similar for both class 3-6 and class 7-8.

These vehicles are subject to FMVSS No. 136 and so must have ESC.

Rear-End Crashes by Vehicle Travel Speed and Roadway Speed Limit

Pre-crash vehicle travel speed is highly important in understanding the heavy vehicle rear-end crash problem and is perhaps the most influential factor in outcome of these crashes. In NHTSA's analysis of the data, travel speed of the striking vehicle was markedly different when comparing non-fatal and fatal rear-end truck crashes. As shown in Figure 1, the percentage of heavy vehicle rear-end crashes with a fatality is greatest at higher travel speeds.

Approximately 89 percent of fatal heavy vehicle rear-end crashes occur at above 80 km/h (50 mph). For non-fatal heavy vehicle rear-end crashes, the trend is more or less reversed, with approximately 83 percent of these crashes occurring at travel speeds below 80 km/h (50 mph). These data illustrate the distribution of a crash problem across all travel speeds.

Note that the figure shows percentage of the total number of fatal or non-fatal crashes. The total number of crashes is much greater for non-fatal crashes.

BILLING CODE 4910-59-P

EP06JY23.001

The speed

limits in heavy vehicle rear-end crashes also show a similar trend. NHTSA categorized the fatal and non-fatal crash data according to posted speed limit at the crash location, as illustrated in Figure 2.

These data show that over 90 percent of heavy vehicle rear-end crashes with a fatality occur on roadways with a posted speed limit higher than 50 mph (80 km/h). This reinforces the association between higher speeds and fatal crash outcome in these types of crashes. In contrast, non-fatal rear-end crashes tend to occur most commonly on roads with lower speed limit, with a peak frequency at speed limits of 45 mph (72 km/h). These data help in understanding the conditions under which heavy vehicle rear-end crashes of different severities occur.

Data are from 2017-2019 FARS and CRSS crash databases, as discussed in the PRIA section on target population.

These data naturally are clustered around 5 mph intervals normally assigned for posted speed limits on roadways.

EP06JY23.002

BILLING CODE 4910-59-C

Safety Problem That Can Be Addressed by AEB

NHTSA identified

the set of crashes that might be prevented by AEB systems equipped on heavy vehicles. To determine these crashes for this NPRM, NHTSA analyzed 2017 through 2019 crash data for heavy vehicles. The 2017 through 2019 years were chosen because they provide the most recent available data, and thus reflect newer model year vehicles, safety technologies, and crash environments.

The crash-related statistics discussed in this section, often depicted as annual averages, are derived from these data.

Data are from 2017-2019 FARS and CRSS crash databases, as discussed in the PRIA section on target population.

Crash data from 2020, although available, were excluded due to a significant reduction in weighted cases for CRSS. The 2020 data was greatly influenced by COVID-19 and might not reflect the long-term trend of crash outcomes, as described in the accompanying PRIA.

To develop a target crash population relevant to AEB, the agency identified crashes that were classified as rear-end crashes as instructed by the FARS/CRSS manual and in which the striking vehicle was a heavy vehicle. NHTSA analyzed rear-end crashes in which the vehicle ahead is categorized as being either stopped, travelling at a lower speed, or decelerating, and also examined a few other categories to account for rear-end crashes that did not fit into the three categories. Additionally, NHTSA included some other cases which, although not classified as rear-end, were multi-vehicle crashes that still involved the front end of a heavy vehicle colliding with the rear-end of another vehicle.

NHTSA believes that AEB will help reduce the severity of rear-end crashes occurring in a wide variety of real-world situations. However, the data analysis presented some rear-end crash cases where, due to a significant sequence of events or other conditions preceding the crash, the agency had less certainty of the extent to which AEB systems would be able to reduce the crash severity. For example, if the data indicated that the heavy vehicle had changed lanes just prior to colliding with a vehicle ahead, there would potentially not have been sufficient time and/or space for the AEB system to properly identify and track that vehicle and brake in time to avoid the crash. As another example, if the road surface conditions were icy and slippery, the AEB system may have been less likely to prevent a crash due to the reduced friction and increased stopping distances. In another example, if the struck vehicle was a motorcycle, NHTSA is uncertain of the AEB system's capacity to perform optimally since motorcycles may be more difficult to detect.

NHTSA is currently conducting research tests to understand AEB performance in light vehicle rear-end crashes with motorcycles. Two types of AEB sensor types (

e.g.,

camera and camera+radar) were investigated. See

www.regulations.gov,

Docket No. NHTSA-2022-0091. A study by the RDW, the vehicle authority in the Netherlands, indicated that adaptive cruise control systems (which detect a vehicle ahead, similar to AEB) had more difficulty detecting motorcycles.

https://www.femamotorcycling.eu/wp-content/uploads/Final%20Report_motorcycle_ADAS_RDW.pdf

(last accessed February 10, 2023).

NHTSA believes that, even in these situations where AEB performance may be partially degraded, having AEB will still be beneficial. It may not, for example, prevent a crash but it may reduce its severity by slowing the

striking vehicle down. However, the agency took a conservative approach and excluded cases such as those above from the target crash population, and included only those cases in which AEB systems would have the opportunity to perform optimally. This approach gives greater confidence that the crashes included in the target crash population would be prevented by having AEB-equipped vehicles.

The PRIA discusses the rear-end crashes that were excluded from the target population.

The result is that out of the 550,000 annual police reported crashes involving heavy vehicles, approximately 60,000 annually are rear-end crashes in which the heavy vehicle was the striking vehicle. Thus, if heavy vehicles were equipped with AEB, a portion of these 60,000 crashes could be prevented. These 60,000 crashes, between 2017 and 2019, resulted in an annual average of approximately 388 fatalities, 30,000 injuries, and 84,000 PDOVs.

By requiring ESC for most class 3 through 6 vehicles, the proposed rule would affect approximately 17,000 rollover and loss of control crashes. These crashes resulted in 178 fatalities, 4,000 injuries, and 13,000 PDOVs, a portion of which could be prevented if class 3 through 6 heavy vehicles were equipped with ESC. These numbers are set forth in Table 7.

Table 7—Target Crash Population

Crashes

Fatalities

Injuries

PDOVs

AEB

60,000

388

30,000

84,000

ESC

17,000

178

4,000

13,000

III. Efforts To Promote AEB Deployment in Heavy Vehicles

Unlike with light vehicles in the U.S., there is currently no voluntary commitment by heavy vehicle manufacturers to begin installing AEB on all new vehicles.

Nor is there a program similar to NHTSA's New Car Assessment Program (NCAP) for heavy vehicles. However, NHTSA and FMCSA have researched heavy vehicle AEB. In addition, Congress, other governmental agencies, and a variety of stakeholders recognize that this technology has the potential to reduce the fatalities, injuries, and property damage associated with heavy vehicle rear-end crashes. The installation rate of AEB in the U.S. vehicle fleet has gradually increased, and the latest generations of the technology are higher performing than the original implementations.

On March 17, 2016, NHTSA and the Insurance Institute for Highway Safety (IIHS) announced a commitment by 20 automakers representing more than 99 percent of the U.S. auto market to make lower speed AEB a standard feature on virtually all new cars no later than Sept 1, 2022.

https://www.nhtsa.gov/press-releases/us-dot-and-iihs-announce-historic-commitment-20-automakers-make-automatic-emergency.

A. NHTSA's Foundational AEB Research

NHTSA has been studying emergency braking technologies since manufacturers first introduced these technologies over fifteen years ago. NHTSA has recognized the safety potential of heavy vehicle AEB for many years and continued to research this technology as it evolved from early generations to its current state. As part of NHTSA's efforts to better understand these new crash avoidance technologies, NHTSA sponsored and conducted numerous research projects focused on AEB and FCW for heavy trucks. NHTSA conducted testing at its in-house testing facility, the Vehicle Research and Test Center, to examine the performance of AEB in different combinations of crash scenarios and speeds.

NHTSA's foundational knowledge of braking technology was built on a long history of work on FMVSS No. 105, “Hydraulic and electric brake systems,” No. 121, “Air brake systems,” and No. 136, “Electronic stability control systems for heavy vehicles.”

FMVSS No. 105 applies to multipurpose passenger vehicles, trucks, and buses with a GVWR greater than 3,500 kg (7,716 lbs.) that are equipped with hydraulic or electric brake systems. This standard sets performance requirements for, among other things, maximum stopping distance, anti-lock braking systems, stability and control under braking (including a curved and wet road surface), and recovery from brake fade.

Brake fade events are associated with speed control on roads with steep or gradual but long downgrades. As brake temperature increases in a drum, its diameter expands as the metal heats up; this means the brake shoe displacement must also increase to be effective. Eventually, the shoe reaches the displacement limit, and then brake effectiveness drops off.

FMVSS No. 121 applies to trucks, buses, and trailers equipped with air (pneumatic) brake systems, with a few exceptions for special vehicle types. Although NHTSA sets no standards regarding the choice between using hydraulic, electric, or air brakes, vehicles with a larger size and load carrying capacity are more likely to have air brakes. Thus, air brakes are typically installed on some class 6 and most class 7-8 vehicles. Lower classes often use hydraulic brakes. A few examples of the requirements in FMVSS No. 121 are maximum stopping distance, having ABS, maintaining stability and control when braking to a stop on a curved and wet roadway test surface, recovering from brake fade, and having an emergency (backup) brake system.

FMVSS No. 136 establishes performance and equipment requirements for electronic stability control systems on truck tractors and certain large buses, for the purpose of reducing crashes caused by rollover or by loss of directional control. This standard currently applies to truck tractors and certain large buses with a GVWR greater than 11,793 kilograms (26,000 lbs.). FMVSS No. 136 requires vehicles to be equipped with an ESC system, and to meet several minimum performance requirements. For example, when driven on a specified J-shaped test lane under a variety of specified conditions and parameters which induce ESC activation, the wheels of the heavy vehicle must remain within the lane.

B. NHTSA's 2015 Grant of a Petition for Rulemaking

In October 2015, NHTSA granted a petition for rulemaking from the Truck Safety Coalition, the Center for Auto Safety, Advocates for Highway and Auto Safety, and Road Safe America. This petition requested “the commencement of a proceeding to establish a safety regulation to require the use of [FCW and AEB] on all vehicles (trucks and buses) with a gross vehicle weight rating (GVWR) of 10,000 pounds (lbs.) or more.” The petitioners maintained that AEB has important benefits and is a technology that has been improving in performance, but that a regulation is needed to optimize the benefits of the

technology and increase the frequency of installation in heavy vehicles. The agency granted this petition on October 16, 2015, noting that NHTSA's research and evaluation were ongoing, and initiated a rulemaking proceeding with respect to vehicles with a GVWR greater than 4,536 kg (10,000 lbs.).

Grant of petition for rulemaking, 80 FR 62487 (October 16, 2015).

C. Congressional Interest

1. MAP-21

In July 2012, the Moving Ahead for Progress in the 21st Century Act was enacted. MAP-21 included Subtitle G, the “Motorcoach Enhanced Safety Act of 2012.”

Section 32705 of MAP-21 directed the Secretary (NHTSA, by delegation) to research and test forward and lateral crash warning systems for motorcoaches and decide whether a corresponding safety standard would accord with section 30111 of the Safety Act. Section 32703(b)(3) directed the Secretary to consider requiring motorcoaches to be equipped with stability enhancing technology, such as electronic stability control, to reduce the number and frequency of rollover crashes, and prescribe a standard if it would meet the requirements and considerations of sections 30111(a) and (b) of the Safety Act.

In response, NHTSA issued FMVSS No. 136, requiring ESC for certain truck tractors and buses (including motorcoaches) with a GVWR greater than 13,154 kg (26,000 lbs.).

Public Law 112-141, Sec. 32705.

Section 32703(b) required a regulation not later than two years after the date of enactment of the Act if DOT determined that such standard met the requirements of the Safety Act.

2. Bipartisan Infrastructure Law

In November 2021, the Bipartisan Infrastructure Law (BIL) was signed into law. Section 23010 of BIL is dedicated to AEB. Section 23010(a) of BIL defines an AEB system as a system on a commercial motor vehicle that, based on a predefined distance and closing rate with respect to an obstacle in the path of the vehicle, alerts the driver of an obstacle and, if necessary, applies the brakes automatically to avoid or mitigate a collision with that obstacle.

Section 23010(b) requires the Secretary to prescribe an FMVSS to require all commercial motor vehicles

subject to FMVSS No. 136 (or a successor regulation) to be equipped with an AEB system. The FMVSS is also required to establish performance standards for AEB systems. BIL directs the Secretary to prescribe the standard not later than two years after the date of enactment of the Act.

As defined in 49 U.S.C. 31101, “commercial motor vehicle” means a self-propelled or towed vehicle used on the highways in commerce principally to transport passengers or cargo, if the vehicle has a gross vehicle weight rating or gross vehicle weight of at least 10,001 pounds, whichever is greater; is designed to transport more than 10 passengers including the driver; or is used in transporting material found by the Secretary of Transportation to be hazardous and transported in a quantity requiring placarding under regulations.

Under Section 23010(b)(2), prior to prescribing the FMVSS, the Secretary is required to conduct a review of AEB systems in use in applicable commercial motor vehicles and address any identified deficiencies in those systems in the rulemaking proceeding, if practicable. In addition, the Secretary is required to consult with representatives of commercial motor vehicle drivers to learn about their experience with AEB (including malfunctions and/or unwarranted activations).

This NPRM is issued to meet these provisions of the BIL. NHTSA conducted a review of AEB systems in use in commercial motor vehicles to identify limits in those systems. A memorandum summarizing this review has been placed in the docket for this NPRM and has informed the development of the proposal. NHTSA is also currently conducting research to study drivers' experiences with collision mitigation technologies, including AEB. Comments are requested on the feasibility of mandating AEB for commercial motor vehicles with GVWR greater than 10,000 pounds which are not currently subject to FMVSS No. 136. This NPRM requests comments from representatives of commercial motor vehicle drivers, and drivers themselves, regarding the experience with the use of AEB systems. This NPRM also includes a series of questions in section VII.E on which NHTSA seeks comment to obtain information about drivers' experiences with AEB (including malfunctions and/or unwarranted activations).

Section 23010(c) of the BIL relates to the regulations of FMCSA, which regulate the operation of commercial motor vehicles. BIL requires an FMCSR ensuring that the AEB systems required by the FMVSS for new commercial vehicles subject to FMVSS No. 136 be in use at any time during which the vehicle is in operation. This NPRM proposes this FMCSR.

FMCSA has also created an apprenticeship program for novice drivers of commercial motor vehicles pursuant to the BIL. The program requires novice drivers to operate vehicles that possess an active braking collision mitigation system, such as AEB. 87 FR 2477, January 14, 2022.

Finally, section 23010(d) of BIL requires DOT to complete a study on equipping a variety of commercial motor vehicles not currently required to comply with FMVSS No. 136 with AEB. This study is to include an assessment of the feasibility, benefits, and costs associated with installing AEB on these vehicles. As discussed in greater detail later, the analysis accompanying this NPRM fulfills this requirement.

D. IIHS Effectiveness Study

In a 2020 report, the Insurance Institute for Highway Safety studied the effectiveness of FCW and AEB technology on class 8 trucks and concluded that safety will improve if more trucks have these technologies installed.

IIHS used data extracted from video camera footage and crash rates of police-reportable crashes. While the study sample did not contain a large number of severe crashes, FCW and AEB were still associated with significant reductions in rear-end crashes involving trucks. On average, between the time of collision and moment of system intervention, the velocity of the striking vehicle was reduced by greater than 50 percent. The study concluded that safety would improve if more trucks had these technologies installed.

The IIHS study was limited to class 8 trucks and involved certain fleets and drivers which may not necessarily be representative of the U.S. fleet as a whole. Because of this limitation, NHTSA could not use the findings to calculate the potential benefits of this proposal.

Teoh, Eric R. (2020, September).

Effectiveness of front crash prevention systems in reducing large truck crash rates.

Arlington, VA: Insurance Institute for Highway Safety. Available at

https://www.iihs.org/topics/bibliography/ref/2211#:~:text=Results%3A%20FCW%20was%20associated%20with,%25%20for%20rear%2Dend%20crashes.

(last accessed August 30, 2022).

Id.

E. DOT's National Roadway Safety Strategy (January 2022)

This NPRM takes a crucial step in implementing DOT's January 2022 National Roadway Safety Strategy to address the rising numbers of transportation deaths occurring on this country's streets, roads, and highways.

At the core of this strategy is the Department-wide adoption of the Safe System Approach, which focuses on five key objectives: safer people, safer roads, safer vehicles, safer speeds, and post-crash care. The Department will launch new programs, coordinate and improve existing programs, and adopt a

foundational set of principles to guide this strategy.

https://www.transportation.gov/sites/dot.gov/files/2022-01/USDOT_National_Roadway_Safety_Strategy_0.pdf

(last accessed August 23, 2022).

The National Roadway Safety Strategy highlights new priority actions that target our most significant and urgent problems and are, therefore, expected to have the most substantial impact. One of the key Departmental actions to enable safer vehicles is initiating a rulemaking to require AEB on heavy trucks. This NPRM proposes a Federal Motor Vehicle Safety Standard to require AEB on heavy trucks and other heavy vehicles.

F. National Transportation Safety Board Recommendations

The National Transportation Safety Board (NTSB) included AEB for commercial vehicles in its 2021-2023 Most Wanted List.

Among other things, NTSB stated that NHTSA should complete standards for AEB in commercial vehicles and require this technology in all highway vehicles and all new school buses.

NTSB Most Wanted List,

https://www.ntsb.gov/Advocacy/mwl/Pages/mwl-21-22/mwl-hs-04.aspx

(last accessed August 23, 2022).

In 2015, NTSB issued a special investigation report,

which summarized previous, as well as new, findings related to AEB in a variety of vehicles. Regarding heavy vehicles, this report presented the following recommendation to NHTSA:

National Transportation Safety Board. 2015.

The Use of Forward Collision Avoidance Systems to Prevent and Mitigate Rear-End Crashes.

Special Investigation Report NTSB/SIR-15-01. Washington, DC. Available at

https://www.ntsb.gov/safety/safety-studies/Documents/SIR1501.pdf

(last accessed August 22, 2022).

• H-15-05: Complete, as soon as possible, the development and application of performance standards and protocols for the assessment of forward collision avoidance systems in commercial vehicles.

In a 2018 special investigation report,

the NTSB discussed two severe accidents involving school buses. In the conclusion of the report, the NTSB stated that AEB could have helped mitigate the severity of one of the accidents, and that ESC could have helped mitigate the other. Accordingly, the following safety recommendations were made or restated to NHTSA:

National Transportation Safety Board. 2018.

Selective Issues in School Bus Transportation Safety: Crashes in Baltimore, Maryland, and Chattanooga, Tennessee.

NTSB/SIR-18/02 PB2018-100932. Washington, DC. Available at

https://www.ntsb.gov/investigations/AccidentReports/Reports/SIR1802.pdf

(last accessed August 22, 2022).

• H-18-08: Require all new school buses to be equipped with collision avoidance systems and automatic emergency braking technologies.

• H-11-7: Develop stability control system performance standards for all commercial motor vehicles and buses with a gross vehicle weight rating greater than 10,000 pounds, regardless of whether the vehicles are equipped with a hydraulic or a pneumatic brake system.

• H-11-8: Once the performance standards from Safety Recommendation H-11-7 have been developed, require the installation of stability control systems on all newly manufactured commercial vehicles with a gross vehicle weight rating greater than 10,000 pounds.

G. FMCSA Initiatives

FMCSA has been engaged in activities to advance the voluntary adoption of AEB for heavy vehicles, primarily through the Tech-Celerate Now (TCN) program. This program focuses on accelerating the adoption of Advanced Driver Assistance Systems (ADAS), such as AEB, by the trucking industry to reduce fatalities and prevent injuries and crashes, in addition to realizing substantial return-on-investment through reducing costs associated with such crashes for the motor carrier. Initiated in September 2019 and completed in February 2022, the first phase of this program encompassed research into ADAS technology adoption barriers; a national outreach, educational, and awareness campaign; and data collection and analysis.

Outreach accomplishments included development of training materials for fleets, drivers, and maintenance personnel related to AEB technology and return-on-investment (ROI) guides; educational videos on ADAS braking, steering, warning, and monitoring technologies; a web-based TCN ADAS-specific ROI calculator; four articles on ADAS technologies; and a program website to host the training materials.

As part of the national outreach campaign, the program was promoted on social media including LinkedIn and Twitter, and FMCSA conducted presentations and booth exhibitions at conferences, webinars, and virtual meetings. Recent efforts have included discussion of a safety effective analysis project that is using two years of naturalistic data collected from AEB and other ADAS technologies at the American Trucking Associations Technology and Maintenance Council's 2022 Annual meeting, the 2022 Midwest Commercial Vehicle Safety Summit, and the 2022 Southeast Commercial Vehicle Safety Summit. The results of this project are expected be published late in calendar year 2023.

Planning is underway for the second phase of the TCN program, which includes an expanded national outreach and education campaign, additional research into the barriers to ADAS adoption by motor carriers, and evaluation of the outreach campaign.

IV. NHTSA and FMCSA Research and Testing

A. NHTSA-Sponsored Research

The following are brief summaries of some of the research NHTSA sponsored relating to strategies to avoid heavy vehicle collisions with lead vehicles. The agency funded several research efforts to assess collision avoidance systems, including AEB.

1. 2012 Study on Effectiveness of FCW and AEB

On August 2012, the University of Michigan Transportation Research Institute (UMTRI) conducted a simulation study under a cooperative agreement between NHTSA and AEB supplier WABCO.

The objective of the study was to estimate the safety benefits FCW and AEB systems implemented on heavy trucks, including single-unit and tractor-semitrailers. The study characterized technology, estimated a target crash population, created a simulated reference crash database, and assessed the impact of the technologies in a simulated environment. These results were then applied to the target crash population. The study not only simulated benefits for equipping heavy trucks with then-available technology, but also simulated benefits for next and future systems that were expected to have enhanced capabilities.

Woodrooffe, J., et al., “Performance Characterization and Safety Effectiveness Estimates of Forward Collision Avoidance and Mitigation Systems for Medium/Heavy Commercial Vehicles,” Report No. UMTRI-2011-36, UMTRI (August 2012). Docket No. NHTSA-2013-0067-0001, available at

https://www.regulations.gov/document/NHTSA-2013-0067-0001.

The study simulated estimates based on next and future systems that would utilize radar as the main sensor, and provided haptic, auditory, and visual warnings to the driver (just as the current in-production system). The in-production system could decelerate the vehicle up to a maximum of 0.35g without any driver intervention. However, it could not react to fixed objects (

i.e.,

objects that were stationary before they were in the range of the radar). The primary improvements expected for the next system included the ability to react and brake at about 0.3g in response to fixed objects and increased braking control authority on stopped and moving vehicles to engage

the foundation brakes to produce as much as 0.6g of longitudinal deceleration. The study used the same increased control authority on stopped and moving vehicles as the next generation system, but required the system to more aggressively react to fixed objects with longitudinal deceleration of up to 0.6g.

Based on these capabilities, the study estimated that equipping all tractor-semitrailers with AEB and FCW would reduce fatalities relative to the base population for current, next, and future generation systems by 24, 44, and 57 percent, respectively. Additionally, the predicted reduction in injuries compared to the base population for current, next, and future generation systems was estimated at 25, 47, and 54 percent, respectively. The combined annual benefit for straight truck and tractor semitrailers, including property damage reduction for current, next, and future generation systems was estimated at $1.4, $2.6, and $3.1 billion, respectively.

The study concluded with multiple observations. The enhancements depicted by the next generation system in comparison to the current generation system were substantially larger than when comparing the next generation to the future generation. These improvements were due mainly to the ability of the system to react to fixed vehicles and the increased braking. Overall, this evaluation depicted that the collision mitigation measures studied would achieve significant benefits.

2. 2016 Field Study

NHTSA sponsored a field study with the Virginia Tech Transportation Institute (VTTI) to assess the performance of heavy-vehicle crash avoidance systems using 150 Class 8 tractor-trailers.

The vehicles were each equipped with a collision avoidance system from one of two companies that included AEB and FCW. The purpose of the study was to evaluate system reliability, assess driver performance over time, assess overall driving behavior, provide data on real-world conflicts, and generate inputs to a safety benefits simulation model.

See “Field Study of Heavy-Vehicle Crash Avoidance Systems” (June 2016), available at

https://www.nhtsa.gov/sites/nhtsa.gov/files/812280_fieldstudyheavy-vehiclecas.pdf

(last accessed June 3, 2022).

The vehicles were operated by drivers for one year with a total of over 3 million miles travelled. Each vehicle was equipped with a data acquisition system that collected roadway-facing video, driver-facing video, activations, and vehicle network data. About 85,000 hours of driving and 885,000 activations were collected across all activation types. Of the sampled 6,000 activations, 264 were AEB activations and 1,965 were impact alerts.

According to the study, safety benefits of collision avoidance systems could be estimated based on data describing driver use of systems and their responses to the activations. Since the systems depict warnings through an audio and visual display, a precise model of the benefits would show how fast drivers react and if reactions vary based on warning type. For 84 percent of the AEB activations, the driver reacted prior to the alert, and 13 percent of the time, the driver responded to the alert. Drivers did not respond to 3 percent of the AEB activations. Over 50 percent of the false AEB activations received driver responses. Average driving speeds and headway distances at the initiation of AEB activations prior to safety-critical events were similar to values recorded for other activations. While at the initiation of many warranted AEB activations, drivers had already implemented braking, every warranted AEB activation did not receive a driver reaction.

The analysis included a driver frustration assessment for each AEB activation. This was a subjective assessment based on whether drivers appeared to show frustration during an activation. Advisory warnings resulted in lower percentages of general frustration. The highest instances of frustration were noted during false activations with frustration noted 11 percent of the time.

In summary, the study found that crash avoidance systems can be effective in collision avoidance. Driver performance and behavior exhibited almost no changes over time, and there was limited frustration with the AEB activations. There were some limitations in the study including varied calibration options between the systems, no control group, different geographical locations, and unequal driving time amongst participants.

3. 2017 Target Population Study

In 2017, NHTSA completed a study on a target population for AEB in vehicles with a GVWR over 4,536 kg (10,000 pounds).

The objective of the study was to determine which forward collisions would theoretically benefit from AEB if all vehicles over 4,536 kg (10,000 pounds) GVWR were equipped with the system. First, NHTSA reviewed literature for then-existing AEB systems manufactured by Bendix and Meritor. Although the systems varied in some ways, they shared a tiered functionality approach, including the sequential use of auditory and visible warnings, automatic torque reduction, application of the engine retarder, and finally automatic brake application as needed.

The research efforts concentrated on the FCW and CIB elements.

See “A Target Population for Automatic Emergency Braking in Heavy Vehicles,” available at

https://crashstats.nhtsa.dot.gov/Api/Public/Publication/812390

(last accessed June 7, 2022).

See page 8 “A Target Population for Automatic Emergency Braking in Heavy Vehicles,” available at

https://crashstats.nhtsa.dot.gov/Api/Public/Publication/812390

(last accessed June 7, 2022).

Second, collisions were sampled from NHTSA and FMCSA's Large Truck Crash Causation Study

for an engineering review because this database provides comprehensive information on heavy vehicle collisions in the United States. The engineering review focused on 29 crashes from the Large Truck Crash Causation Study that involved injuries and fatalities to determine whether FCW and/or CIB would be effective in preventing the crash. Effectivity was defined as both reviewing engineers determining that there was a 50 percent chance or greater that the crash would be prevented. The analysis determined that FCW and CIB would both be effective in preventing 17 of the 29 crashes, much more often than cases in which only either was effective or neither was effective. Considering a summary of the weighted effectiveness, the combination of FCW and CIB were effective in 50 percent of the cases. While FCW alone was effective in 23 percent of cases, there was a significant 21 percent of cases where neither FCW nor CIB was effective.

See “Large Truck Crash Causation Study,” available at

https://www.fmcsa.dot.gov/safety/research-and-analysis/large-truck-crash-causation-study-analysis-brief

(last accessed October 19, 2022).

Additionally, there was at least one case that consensus was not reached regarding the effectiveness of CIB, and there was no investigation of crashes of lower severity where only property damage resulted.

Third, the outcomes from the first two phases allowed for the development of filters to identify the categories of collisions that AEB would improve. These filters were then implemented to collisions in NHTSA's crash databases to approximate how many collisions annually AEB could have prevented. A combination of data from the FARS and the GES was used for the calculations while ensuring that an overlap in fatal crashes was removed to prevent duplicate tallies. Vehicle collision information for the United States

involving injuries and fatalities for years 2010 to 2012 was utilized from these databases.

Both injury-related and fatal collisions totaled 5,457,387, and this total was filtered to determine the target population. The filtering exclusions were made cautiously in order to yield a conservative benefit estimate. Crashes during which the subject vehicle departed from its original travel lane and the lead vehicle maintained the lane were not included. Similarly, collisions involving the lead vehicle changing from the original lane and the subject vehicle remaining in its lane were excluded. Additional exclusions included collisions on icy and snowy roads, situations where the lead vehicle turns from a perpendicular street in front of the subject vehicle, cases involving acceleration maneuvers to avoid collision, collisions where the lead vehicle was obscured by an object, collisions into motorcycles, and cases where the subject vehicle was traveling on a curved road toward an object such as a guardrail.

LTCCS was not selected due to the age of the crash data, for it is possible heavy vehicle collisions differ tremendously since 2001. The UMTRI Trucks Involved in Fatal Accidents study (

https://deepblue.lib.umich.edu/bitstream/handle/2027.42/107389/48532_A56.pdf?isAllowed=y&sequence=1,

last accessed June 3, 2022) was excluded because its detailed information regarding vehicle style and driving time is only provided for collisions involving fatalities, where data for collisions of less severity involving only injuries would not be available.

Fourth, the target population estimated in the third phase was modified to reflect recent and probable future regulations. This modification eliminated collisions that would be avoided based on the implementation of other required technologies that had not yet completely proliferated in heavy vehicles. Accounting for safety equipment including ESC, ABS, and speed limiters allowed for the overall target population to be modified to reflect the anticipated number of future collisions. Crashes that were included in the final future target population were those involving heavy vehicles in which the rear-end crash resulted in injuries and fatalities. Further, the crashes were refined to include only crashes where both vehicles remained in the original lane after the crash was deemed imminent and collisions where lane changes prior to crash imminency were allowed as long as only one of the vehicles changed lanes. Additionally, situations where the driver attempted to steer around the collision or used insufficient braking were included.

After all adjustments were completed, the study estimated a target population of 11,499 crashes annually involving 7,703 injured persons and 173 fatalities. It also discussed possible sampling error as well as three sources of uncertainty. However, the size of a target population provided only an estimated upper bound to the benefits at that time. The report added value in the detailed descriptions of affected crashes and subpopulation breakouts that have traditionally fed into benefits estimation.

4. 2018 Cost and Weight Analysis

In 2018, Ricardo Inc. completed a study sponsored by NHTSA that focused on the cost and weight implications of requiring AEB on heavy trucks. The study aimed to determine the product price, total system cost, incremental consumer price, and weight of FCW and AEB systems on heavy trucks to provide insight into the safety and efficiency benefits of using the systems.

The initial steps of the study were vehicle research, vehicle segregation, and vehicle selection. Model year 2015-2018 heavy vehicles manufactured by Ford, Cascadia, Volvo, Daimler, and International LT were chosen for teardown examination and ranged in mean annual sales from approximately 24,000 to 86,542. The associated FCW and AEB systems installed on these vehicles were manufactured by Delphi Technologies, Meritor, Bendix Commercial Vehicle Systems, and Detroit Assurance (Daimler).

Ricardo, Inc. (2018), “Cost and Weight Analysis of Heavy Vehicle Forward Collision Warning (FCW) and Automatic Emergency Braking (AEB) Systems for Heavy Trucks” Van Buren Township, MI.

Service technician consultations, manuals, and OEM parts descriptions were used to itemize components of the FCW and AEB systems. Specific assessments of the related displays, sensors, mounting hardware, and other elements of the FCW and AEB systems were provided to prevent extraneous parts from being included in the cost and weight evaluations. The cost and weight evaluations were executed by a group of automotive system and integration experts, cost modeling specialists, and procurement personnel. A bill of materials was compiled using a “teardown” process to inventory the parts, define manufacturing processes, and ascertain materials utilized. Specialized cost software allowed for calculation of cost and weight.

In general, components that were not distinct to the FCW and AEB systems were not included in the cost and weight evaluation. Therefore, shared parts such as electronic control units and wiring harnesses were not considered as additions if they were already incorporated into the vehicle configuration without FCW/AEB. The manufacturing costs were estimated, factoring in research and development, labor, material costs, machinery, machine occupancy and tooling.

The five selected vehicles were the Ford F-Series Super Duty, Freightliner M2-106, Freightliner Cascadia, International LT, and Volvo VNL. While there was some overlap of similar components, the FCW and AEB systems in the five selected vehicles had substantial variation amongst the system mechanisms and functionality. Based on these differences the vehicles were separated into four groups, and the average manufacturing costs and weights were assessed for each category. Overall, the average incremental cost to manufacturers for these FCW/AEB systems ranged from $44.23 to $197.51; and associated end-user prices ranged from $70.80 to $316.18. Additionally, the average incremental weights ranged from approximately 0.46 to 3.10 kg.

B. VRTC Research Report Summaries and Test Track Data

1. Relevance of Research Efforts on AEB for Light Vehicles

AEB was first introduced on light vehicles. For this reason, NHTSA's research and testing of AEB systems began with light vehicles and was subsequently used to inform NHTSA's work on heavy vehicle AEB.

NHTSA conducted extensive research on AEB systems to support development of the technology and eventual deployment in vehicles. There were three main components to this work. Early research was conducted on FCW systems that warn drivers of potential rear-end crashes with other vehicles. This was followed by research into AEB systems designed to prevent or mitigate rear-end collisions through automatic braking.

NHTSA's earliest research on FCW systems began in the 1990s, at a time when the systems were under development and evaluation had been conducted primarily by suppliers and vehicle manufacturers. NHTSA collaborated with industry stakeholders to identify the specific crash types that an FCW system could be designed to address, the resulting minimum functional requirements, and potential objective test procedures for evaluation.

In the late 1990s, NHTSA

worked with industry to conduct a field study, the Automotive Collision Avoidance System Program. NHTSA later contracted with the Volpe National Transportation Systems Center (Volpe) to conduct data analyses of data recorded during that field study.

From this work, NHTSA learned about the detection and alert timing and information about warning signal modality (auditory, visual, etc.) of FCW systems, and predominant vehicle crash avoidance scenarios where FCW systems could most effectively play a role in alerting a driver to brake and avoid a crash. In 2009, NHTSA synthesized this research in the development and conduct of controlled track test assessments on three vehicles equipped with FCW.

This research was documented in a report, “Development and Validation of Functional Definitions and Evaluation Procedures for Collision Warning/Avoidance Systems,” Kiefer, R., et al.,

DOT HS 808 964, August 1999. Additional NHTSA FCW research is described in Zador, P.L., et al., “Final Report—Automotive Collision Avoidance System (ACAS) Program,” DOT HS 809 080, August 2000; and Ference, J.J., et al., “Objective Test Scenarios for Integrated Vehicle-Based Safety Systems,” Paper No. 07-0183, Proceedings of the 20th International Conference for the Enhanced Safety of Vehicles, 2007.

Najm, W.G., Stearns, M.D., Howarth, H., Koopmann, J., and Hitz, J., “Evaluation of an Automotive Rear-End Collision Avoidance System,” DOT HS 810 569, April 2006 and Najm, W.G., Stearns, M.D., and Yanagisawa, M., “Pre-Crash Scenario Typology for Crash Avoidance Research,” DOT HS 810 767, April 2007.

Forkenbrock, G., O'Harra, B., “A Forward Collision Warning (FCW) Program Evaluation, Paper No. 09-0561, Proceedings of the 21st International Technical Conference for the Enhanced Safety of Vehicles, 2009.

NHTSA's research and test track performance evaluations of AEB began around 2010. The agency began a thorough examination of the state of forward-looking advanced braking technologies, analyzing their performance and identifying areas of concern or uncertainty, to better understand their safety potential. NHTSA issued a report

and a request for comments (RFC) seeking feedback on its CIB and DBS research in July 2012.

Specifically, NHTSA wanted to enhance its knowledge further and help guide its continued efforts pertaining to AEB effectiveness, test operation (including how to ensure repeatability using a target or surrogate vehicle), refinement of performance criteria, and exploration of the need for “false positive” tests to minimize the unintended negative consequences of automatic braking in non-critical driving situations where a crash was not imminent.

The agency's initial research and analysis of CIB and DBS systems were documented in a report, “Forward-Looking Advanced Braking Technologies: An analysis of current system performance, effectiveness, and test protocols” (June 2012).

http://www.regulations.gov,

NHTSA 2012-0057-0001.

77 FR 39561.

NHTSA considered feedback it received on the RFC and conducted additional testing to support further development of the test procedures. The agency's work was documented in two additional reports, “Automatic Emergency Braking System Research Report” (August 2014)

and “NHTSA's 2014 Automatic Emergency Braking (AEB) Test Track Evaluations” (May 2015),

and in accompanying draft CIB and DBS test procedures.

https://www.regulations.gov,

NHTSA 2012-0057-0037.

DOT HS 812 166.

https://www.regulations.gov,

NHTSA 2012-0057-0038.

In 2016, NHTSA published a report identifying the most recurrent AEB-relevant pre-crash scenarios for heavy vehicles. NHTSA identified the three most recurrent situations as a heavy vehicle moving toward a stopped lead vehicle, a heavy vehicle moving toward a slower moving lead vehicle, and a heavy vehicle moving toward a lead vehicle that is decelerating.

These were the same three crash scenarios that had been identified as the most prevalent AEB-relevant crash scenarios for light vehicles.

Boday, C., et al., “Class 8 Truck-Tractor and Motorcoach Forward Collision Warning and Automatic Emergency Braking Test Track Research—Phase I,” Washington, DC: National Highway Traffic Safety Administration (June 2016). Docket No. NHTSA‐2015-0024-0004.

2. Phase I Testing of Class 8 Truck-Tractors and Motorcoach

In 2016, NHTSA published its first report on track-testing of AEB for heavy vehicles. The previous studies describing the test procedures for light vehicles provided a framework for the establishment of heavy vehicle test procedures. Since test procedures were not yet developed for heavy vehicles, the goal of the research was to first adapt existing testing protocols for light vehicle AEB and then follow these adapted test procedures to quantify the performance of FCW and AEB systems on heavy vehicles. The research was conducted in two phases.

NHTSA's Phase I work began with using a combination of the specific test situations established for NHTSA's NCAP for assessment of FCW and AEB systems and a modified version of the light vehicle test procedures to create heavy vehicle draft research test procedures. NCAP tests involved use of a strikable surrogate vehicle; however, for early heavy vehicle Phase I work, NHTSA used a surrogate lead vehicle comprised of canvas-covered foam to exhibit geometric and reflective features of the rear of a passenger car. The testing for Phase I was performed with four heavy vehicles outfitted with FCW and AEB, including three Class 8 truck-tractors and one Class 8 motorcoach. Specifically, the four Class 8 vehicles were a 2006 Volvo VNL 64T630 6x4 tractor, a 2006 Freightliner Century Class 6x4 tractor, a 2012 Freightliner Cascadia 6x4 tractor, and a 2007 MCI 56-passenger motorcoach (bus). Each vehicle was equipped with ABS, ESC, FCW, and AEB systems. The 2006 and 2012 Freightliners and the MCI motorcoach employed a Meritor WABCO system, and the 2006 Volvo was equipped with a Bendix Wingman Advanced system. In general, the FCW and AEB systems utilized a front bumper mounted sensor to detect objects in front of the vehicle and a display to warn the driver with audio and visual alerts.

For each vehicle, NHTSA planned to run ten tests that are summarized in Table 8. These situations covered the three most common AEB-relevant pre-crash scenarios, as well as two false positive tests and two tests performed at different weighted conditions.

Table 8—Phase I Test Scenarios

Scenario

Lead vehicle

speed (km/h)

Subject vehicle

speed (km/h)

Lightly loaded

(number of trials)

Loaded at GVWR

(number of trials)

Lead vehicle Stopped

Lead Vehicle Moving

Lead Vehicle Decelerating

Steel Trench Plate False Positive

N/A

Steel Trench Plate False Positive

N/A

The test scenarios were defined by the initial speeds of the subject vehicle and lead vehicle, and the starting headway distance between the vehicle was monitored. For all the tested scenarios, the test driver was instructed to modulate the accelerator pedal to maintain the desired test speed until FCW initiated, upon which the accelerator pedal input was removed. Steering was applied to maintain lateral position test tolerances to the lead vehicle. Manual brake pedal applications were only applied in certain scenarios where AEB was not designed to activate, or an impact occurred with the leading surrogate vehicle. Additionally, the previously described test situations were conducted under both a lightly loaded condition and a fully loaded vehicle weight condition (

i.e.,

loaded up to the vehicle's GVWR). Based upon potential damage to the subject vehicle, the feasibility of completing each test scenario with the specific load, and the fact that there was no discernable difference between the performance under the lightly loaded and GVWR loaded conditions in the trials executed, some of the speed combinations were not investigated under both loads. The false positive tests were conducted by driving the selected vehicles toward and over a steel trench plate to determine if these commonly used road construction covers would trigger false alerts or unintentional automatic braking.

Stationary lead vehicle testing was limited to the 2006 Volvo, as it was equipped with the only system that would trigger an FCW on stationary vehicles. At the time these evaluations were performed, none of the systems tested were designed to activate AEB on stationary vehicles. During every slower moving lead vehicle test, FCW was activated. Additionally, every vehicle's AEB activated and avoided collision during each slower moving test performed with a subject vehicle speed of 40 km/h, and a lead vehicle speed of 16 km/h.

The lead vehicle decelerating test was used to evaluate all four heavy vehicles, but multiple test adjustments had to be applied. For the lead vehicle decelerating test performed with both the subject and lead vehicle speeds of 40 km/h, the lead vehicle was slowed to 8 km/h instead of a stop to account for the failure of the subject vehicles to activate AEB for stopped vehicles. Once the change was implemented, both the FCW and the AEB systems were activated, and speeds were reduced. Collisions between the subject and lead vehicle did occur, but testing of this scenario mainly led to the observation that the test procedure's headway would also have to be adjusted since heavy vehicles have different braking capabilities than light vehicles.

The steel trench plate false positive test was performed using the 2006 Volvo, 2006 Freightliner, and 2007 MCI at 40 km/h and 72 km/h.

For both velocities examined, the 2006 Freightliner and 2007 MCI exhibited no false positives in all five trials. However, the 2006 Volvo triggered unnecessary auditory warnings in all five trials for both velocities. None of the false positive testing trials resulted in AEB system activation.

The 2012 Freightliner was not evaluated with steel trench plate scenario due to the short window that the vehicle was available for testing.

During this early testing, the surrogate lead vehicle was towed onto the test track and fixed laterally in the test lane via a low-profile plastic monorail track. Initially, the test system employed a low-stretch rope to pull the surrogate lead vehicle by a tow vehicle. This configuration performed well in the slower moving lead vehicle situation because the lead vehicle moves at a constant velocity, allowing the tow rope to stay in tension. In contrast, when testing the lead vehicle decelerating scenario, the tension in the tow rope was not maintained once the tow vehicle decelerated, and subsequently the tow rope was prone to becoming stuck under the surrogate lead vehicle. This issue resulted in a loss of surrogate lead vehicle lateral stability and consequently decreased the test repeatability.

To address this shortcoming, the foam surrogate lead vehicle was replaced with a vertical cylinder wrapped with a layer of radar reflective material secured to the top of a movable platform with more consistent and stable deceleration properties. However, because the cylinder was not representative of a real vehicle, this was identified as needing further development and modification of the test protocols.

A significant portion of this early AEB testing focused on developing draft research test procedures that could be used to safely and objectively assess AEB performance. The development history of test protocols is important for two reasons. First, it explains how NHTSA came to the conclusion to propose the performance parameters described in the notice and its basis that the performance requirements are objective and practicable. Second, it provides some context as to some of the limitations of early performance evaluations of AEB for heavy vehicles. In general, this initial phase of research demonstrated that the scenarios were generally repeatable and practical, and the tests showed additional development would potentially result in better controlled deceleration and stability of the lead vehicle.

3. Phase II Testing of Class 8 Truck-Tractors

NHTSA's primary objectives of the Phase II efforts were to continue to develop the FCW and AEB test procedures executed in Phase I such that they could be effectively utilized on a closed-course track test to assess performance of heavy vehicle FCW and AEB systems. For this testing, NHTSA used four Class 8, truck-tractors, three of which were from Phase I. The fourth vehicle from Phase I, the MCI motorcoach, was replaced with a 2016 Freightliner. Specifically, these subject vehicles were a 2016 Freightliner, a 2012 Freightliner, a 2006 Volvo, and a 2006 Freightliner. Like in Phase I, all vehicles were outfitted with ABS, ESC, FCW, and AEB systems. Both the 2006 and 2012 Freightliners employed the Meritor WABCO system, the 2016 Freightliner had the Detroit Assurance Safety System, and the 2006 Volvo utilized the Bendix Wingman Advance system. All AEB systems on the selected vehicles utilized radar installed on the front bumper and each AEB system provided auditory and visual alerts. For Phase II testing, NHTSA used the test scenarios from Phase I; however, a second false positive test scenario was added. Specifically, NHTSA investigated a pass-through test from

Europe's AEB requirements

involving a subject vehicle being driven in a central lane between two parked vehicles.

United Nations, “Uniform provisions concerning the approval of motor vehicles with regard to the Advanced Emergency Braking Systems (AEBS)” 2013. Available at

https://unece.org/fileadmin/DAM/trans/main/wp29/wp29regs/2013/R131e.pdf

(last accessed February 10, 2023).

While other standards

were considered for this research study, the use of United States collision data and different testing goals led to establishment of specific test procedures. While vehicle test speeds were similar, with some overlap, NHTSA's test procedures included higher velocity tests to be executed at 55 km/h with more specifications governing the test conditions and test completion. NHTSA's Phase II test scenario matrix is summarized in Table 9.

The following were among the standards considered: International Organization for Standardization (ISO) 22839:2013, “Intelligent transport systems—Forward vehicle collision mitigation systems—Operation, performance, and verification requirements; ISO 15623:2013, “Intelligent transport systems—Forward vehicle collision warning systems—Performance requirements and test procedures,” and SAE International recommended practice J3029, “Forward collision warning and mitigation vehicle test procedure—Truck and bus.”

Phase II also further enhanced the testing of Phase I by implementing a new strikable surrogate vehicle (SSV) system as the lead vehicle. The SSV system was created for NHTSA's light vehicle AEB assessment and was engineered to enhance test repeatability and lateral stability in higher velocity tests.

Table 9—Phase II Test Scenarios

Scenario

Lead vehicle

speed

(km/h)

Subject vehicle

speed

(km/h)

Lightly loaded

(number of trials)

Loaded at GVWR

(number of trials)

Lead Vehicle Stopped

Lead Vehicle Moving

Lead Vehicle Decelerating

6 or 8

Steel Trench Plate False Positive

N/A

Steel Trench Plate False Positive

N/A

Stationary Vehicle False Positive

N/A

The SSV served as the lead vehicle or the vehicle test device (VTD) in the AEB tests. The rear of the SSV was designed to depict features of a typical passenger car. The carbon fiber surrogate exemplified these aspects, considering physical measurements, reflective properties, and visual characteristics. Its structure was not only developed to be detected as a real vehicle by the AEB systems, but it was also intended to endure wind gusts and recurrent impacts up to approximately 40 km/h. The required surrogate test velocities and deceleration of the VTD were achieved by a tow vehicle equipped with a brake controller in conjunction with a towed two-rail track used to move the SSV during the test.

NHTSA implemented changes in the test procedures from Phase I to Phase II. The Phase II test procedures contained more detail as input from within NHTSA and data collected during both phases of heavy vehicle research were used to develop and refine the procedures. For example, the test procedures contained structure for test scenario descriptions, minimum data channels to collect, and general testing requirements (

e.g.,

ambient temperature range, wind, speed, brake burnish, etc.). Definitions were added for when the initial test conditions started, and more detail was added to the definition of when a test trial ended. The test conditions were established to be on dry, straight roadways in the daylight, based on a previous analysis of crash data and observed safety critical events in field operation testing. FCW activation, AEB activation, collision detection, and accelerator pedal release time were measured in the tests. Similar to Phase I, the testing of each scenario occurred under two different load conditions.

After reviewing the Phase I test outcomes, NHTSA determined that the lead vehicle stopped scenario could only be assessed by the latest model year test vehicle outfitted with a capable AEB system. In Phase II, the subject vehicle traveled 40 km/h and approached a stationary lead vehicle in the same lane. Valid trials required the driver to remain centered in the traveling lane and continue driving at the target velocity until AEB was triggered. Once AEB was triggered, the test driver fully released the accelerator pedal, and the driver was not allowed to use the brake pedal of the test vehicle unless the vehicle collided with the lead vehicle or if the AEB system completely stopped the vehicle. The results showed that FCW was activated, followed by automatic braking by the AEB system in all 8 trials performed under the GVWR condition.

The lead vehicle moving test situation was evaluated at multiple velocity combinations for all four test vehicles. During this test, the subject test vehicle traveled at 40 km/h or 75 km/h and approached a slower-moving lead vehicle traveling at 15 km/h or 35 km/h, respectively, in the same lane. Valid trials required the driver to remain centered in the traveling lane and continue driving at the target velocity until AEB was triggered. Once AEB was triggered, the test driver fully released the accelerator pedal. Testing for this scenario was conducted for both lightly loaded and GVWR conditions. All of the vehicles tested consistently issued FCW alerts and activated the AEB systems; however, impacts occurred.

The lead vehicle decelerating situation was executed with all the test vehicles except the 2006 Volvo due to its Phase I performance. Two initial velocity and initial headway combinations of the subject and lead vehicles were tested (

i.e.,

40 km/h and 80 m; 55 km/h and 23 m). After a short period of steady state driving using constant speeds and a constant headway, the lead vehicle was braked at approximately 0.3g while traveling in the same lane as the subject vehicle. The subject vehicle driver kept the subject vehicle centered in the traveling lane and continued driving until AEB was triggered. Under both the lightly loaded and GVWR load conditions testing was completed.

The lead vehicle decelerating test scenario with initial test speeds of 55 km/h and 23 m of headway presented the greatest challenges when compared to other tests. In Phase II, the initial headway was changed from 30.5 m to 23

m to keep the lead vehicle from transitioning to a stopped lead vehicle test scenario near the end of a test trial, as it did in Phase I testing with a headway of 30.5 m. Testing for this scenario was conducted for both lightly loaded and GVWR conditions and all four vehicles. All of the vehicles consistently issued FCW alerts and activated the AEB systems; however, most tests resulted in impact.

Two false positive test types were also conducted. The steel trench plate scenario was executed at 40 km/h and 75 km/h for all test vehicles. Each vehicle was evaluated in the GVWR load condition, but only the 2016 Freightliner was also assessed in the lightly loaded condition. Most of the vehicles did not exhibit any FCW or AEB activations in these tests. However, one vehicle's FCW/AEB system perceived the steel trench plate as a stationary object on the path of travel and the reaction to this false positive detection was not consistent in terms of warning time, brake initiation time, and deceleration level. The second test involved two stationary vehicles in lanes on either side of the test vehicle's travel lane; and only the 2012 Freightliner and the 2016 Freightliner were evaluated under the GVWR load condition. Neither vehicle exhibited any false FCW or AEB activations in this test.

Overall, the Phase II test results demonstrated the ability of the vehicles and AEB systems tested to avoid contact in the lead vehicle stopped and lead vehicle moving test scenarios at the different velocities and achieve no collisions. These capabilities extended to the lead vehicle decelerating tests performed at 40 km/h and a headway of 80 m. In contrast, there was a much lower likelihood of these vehicles avoiding contact with the lead vehicle using an initial speed of 55 km/h and a headway of 23 m.

4. NHTSA's 2018 Heavy Vehicle AEB Testing

NHTSA conducted test track research in 2017 and 2018 on heavy vehicles equipped with FCW and AEB. This section describes the third phase of NHTSA's heavy vehicle testing and the results from three single-unit trucks. These trucks included a class 3 2016 Freightliner 3500 Sprinter, a class 6 2017 International 4300 SBA 4x2, and a class 7 2018 Freightliner M2-106. The main goal of this third phase was to develop objective test procedures for evaluating the performance of heavy vehicles equipped with FCW and AEB systems on a closed course test track.

Table 10—Phase III Test Scenarios

Scenario

Lead vehicle

speed

(km/h)

Subject vehicle

speed

(km/h)

Initial

headway

(m)

Lead Vehicle Stopped

Lead Vehicle Moving

Lead Vehicle Decelerating

Steel Trench Plate False Positive

N/A

Steel Trench Plate False Positive

N/A

105

Stationary Vehicle Pass-Through False Positive

N/A

In this third phase of research, the newly developed heavy vehicle AEB test procedures included test conditions where the driver applies the subject vehicle brakes while approaching a lead vehicle, but with an input insufficient to prevent a rear-end crash, to complement the previously developed scenarios.

The 2017 International 4300 was outfitted with a Bendix system which includes FCW and AEB. This system was enhanced since Phase II of NHTSA's research where, in Phase III, it used camera and radar to engage automatic emergency braking and demonstrated the ability to respond to traveling and stationary vehicles. The FCW provided alerts at velocities greater than 8 and 15 km/h for moving and stationary objects, respectively. For the AEB system to be engaged, the vehicle had to travel above 25 km/h.

The 2018 Freightliner M2-106 was outfitted with an OnGuardACTIVE Collision Mitigation system which features FCW and AEB. This system used radar to engage automatic emergency braking and displayed the ability to respond to traveling and stationary vehicles. The FCW provided alerts with visual and auditory cues and a braking warning was issued when the AEB was activated. In order for the AEB system to be engaged, the vehicle had to travel above 25 km/h.

The study concluded that the test procedures were reproducible and appropriate for heavy vehicles outfitted with FCW and AEB systems. After Phase II, the test procedures and scenarios were updated and applied to heavy vehicles with different weight classifications. The inclusion of heavy vehicles with updated AEB systems in Phase III allowed for evaluation of more systems in the lead vehicle stopped scenario; during the lead vehicle stopped evaluations with no driver braking, at least one vehicle experienced no collisions for all trials tested. This showed improvement in comparison to the prior phase, which was only able to test lead vehicle stopped on one vehicle and resulted in multiple collisions. The lead vehicle moving scenario test results also displayed improvement where the percentage of collisions decreased in comparison to Phase II. Overall, the outcomes showed that the FCW/AEB systems have the capacity for being able to decrease rear-end collisions by exhibiting velocity reductions before a collision or avoiding contact with a lead vehicle entirely. While some FCW false positives were observed, the overall results depicted that the systems have the ability to avoid collision on the test track.

The results of this research show that the test procedures are applicable to many heavy vehicles and indicate that performance improvements in heavy vehicles equipped with these safety systems can be objectively measured.

Further, this was the first phase of the series that was able to apply the test procedures to single-unit trucks across multiple weight classifications; and new test scenarios were added.

Salaani, M.K., Elsasser, D., Boday, C., “NHTSA's 2018 Heavy Vehicle Automatic Emergency Braking Test Track Research Results,” SAE International. J Advances & Current Practices in Mobility 2(3):1685-1704, 2020, doi:10.4271/2020-01-1001.

5. NHTSA's Research Test Track Procedures

NHTSA's most recently published heavy vehicle AEB research test track

procedures were published in March 2019 and evaluate AEB performance in crash-imminent scenarios both with and without manual brake pedal applications.

These procedures, with some modification, form the basis for the proposed test procedure in this NPRM.

Elsasser, D., Salaani, M.K., & Boday, C., “Test track procedures for heavy-vehicle forward collision warning and automatic emergency braking systems,” Report No. DOT HS 812 675, Washington, DC: National Highway Traffic Safety Administration (March 2019). Available at

https://rosap.ntl.bts.gov/view/dot/42186/dot_42186_DS1.pdf

(last accessed June 28, 2022).

The test procedures were based upon prior research and include the lead vehicle stopped, lead vehicle moving, and lead vehicle decelerating test scenarios, as well as the steel trench plate and stationary vehicles false positive scenarios. The testing was divided into three phases. First, the subject vehicle and the lead vehicle are situated on the test track to the proper location and test velocity. The second stage involves determining whether the vehicles have met the proper starting test conditions to achieve valid and reproducible test outcomes. The third and final stage serves to assess test validity and system performance as well as response to any FCW or AEB triggers. In the research test procedure, if an invalid test is detected, the test is repeated until at least seven valid test attempts are completed. Testing was executed during daylight, avoiding inclement weather and irrelevant obstructions such as overhead signs, bridges, overpasses, etc. For test procedures that include manual brake pedal applications, the pedal was displaced at a rate of 254 mm/s to achieve a target longitudinal acceleration of −3.0 m/s

, simulating a manual brake pedal application of a panicked driver. Test procedures for brake pedal input characterization and verification assessment are described for checking uniformity and to ensure the set braking magnitude and response can be achieved.

The lead vehicle stopped test scenario requires the test subject vehicle to be driven toward the stationary lead vehicle at 40 km/h. The subject vehicle is to maintain its velocity and relative lateral position to the straight testing path as it advances toward the lead vehicle. When the time to collision is equal to 5 seconds there is a nominal separation distance of 56 m between the front of the subject vehicle and the rear of the lead vehicle. Once braking is initiated, the accelerator pedal input of the subject vehicle is discontinued fully within 0.5 seconds after the start of braking. For lead vehicle stopped tests performed with insufficient brake pedal applications, the brake pedal is applied at a time to collision of 1.51 seconds. The point at which the brake pedal rate exceeds 50 mm/s is used to define the beginning event of brake pedal input. The conclusion of testing is marked by a collision between the subject and lead vehicle or the subject vehicle stopping prior to colliding with the lead vehicle. The test procedures are repeated until seven valid test trials are obtained for each lead vehicle stopped test with and without brake pedal applications, to obtain a total of 14 valid tests.

The test procedure for the lead vehicle moving scenario is similar for its two vehicle speed combinations. The subject vehicle travels to reach the target speed of 40 or 75 km/h for a minimum of 1 second; and the lead vehicle travels at 15 or 35 km/h, respectively. Prior to approaching the lead vehicle there should be a separation distance of at least 100 m. Additionally, by a time to collision equal to 5 seconds, the separation range is 35 m for 40 km/h and 56 m for 75 km/h. Once the subject vehicle encounters the lead vehicle and braking is automatically initiated, the subject vehicle accelerator pedal was fully released within 0.5 seconds.

The lead vehicle decelerating test procedure starts with the subject vehicle traveling toward the lead vehicle while maintaining an 80 m separation distance. Both the subject vehicle and the lead vehicle are required to reach and maintain a velocity of 40 km/h for at least 1 second while keeping the headway distance. Once the subject vehicle encounters the lead vehicle and braking is initiated, the subject vehicle accelerator pedal was fully released within 0.5 seconds. This test procedure is repeated with similar steps for a 55 km/h velocity and a 23 m separation distance.

In order to evaluate false positives, the steel trench plate test scenario was executed at 40 and 75 km/h, and the stationary vehicles test was completed at 50 km/h. For the seven test trials performed at 40 and 75 km/h, a short edge of the rectangular steel trench plate was centered on the roadway about the x-axis. The subject vehicle was driven toward the steel trench plate such that an initial 110.0 m headway existed, and a nominal velocity of 40 or 75 km/h was maintained for at least 1.0 second. The test initial test condition began when the separation distance between the subject vehicle and steel trench plate was 56 m and 105 m for 40 and 75 km/h, respectively. Once the subject vehicle encountered the steel trench plate at a headway of 16.83 or 40.88 m for 40 and 75 km/h, respectively, the brakes of the subject vehicle were engaged. The test ends when either the subject vehicle drives over the steep trench plate or the subject vehicle stops before crossing over the steel trench plate.

The preliminary conditions of the stationary vehicles test involved two vehicles parked with a lateral separation of 4.5 m. These two vehicles were faced in the forward direction of the test track and were aligned. The subject vehicle was driven along the test track with a 100.0 m headway from the stationary vehicles. The subject vehicle was then driven to maintain a velocity of 50 km/h for at least 1.0 second. The starting test condition is a headway of 60 m where the steering wheel of the subject vehicle was controlled to center the vehicle along the test track. Once the subject vehicle encountered the stationary vehicles at a range of approximately 23.74 m the subject vehicle accelerator pedal was fully released within 0.5 seconds of the initiation of braking.

6. 2021 VRTC Testing

The test track data that follows represents vehicle performance with the latest generation AEB systems and the procedures and conditions proposed in this NPRM largely match the procedures and conditions used for this testing.

2021 Freightliner Cascadia

The 2021 Freightliner Cascadia was tested under the lead vehicle stopped, lead vehicle moving, and lead vehicle decelerating scenarios at the NHTSA VRTC in 2021. The GVT was used as the lead vehicle in these test scenarios. The lead vehicle stopped scenario was executed at multiple initial subject vehicle velocities from 20 km/h up to 95 km/h. While contact with the VTD occurred at 20, 25, 30, and 35 km/h, there were measurable speed reductions. At test velocities between 40 and 85 km/h, no collisions were observed. Collisions also occurred at 90 and 95 km/h, but the FCW at both speeds was issued earlier than 2 seconds before contact. Ten additional test trials were conducted at 40 km/h, and only one trial resulted in contact. Four additional test trials were executed at 50, 60, 70, 80, and 85 km/h; in all four trials, there were no collisions at three speeds and one collision at two speeds (

i.e.,

80 and 85 km/h, respectively) which ultimately resulted in a speed reduction when compared to the other trials.

The lead vehicle moving scenario was performed at several combinations of subject vehicle and lead vehicle initial speeds. The first set of eight trials

involved the subject vehicle at a range of velocities of 30 km/h to 90 km/h and the initial speed of the lead vehicle was 20 km/h for each. Contact occurred only at the 30 and 60 km/h test velocities. The initial speeds for the subject vehicle and lead vehicle for the second set of eight trials was 40 and 15 km/h, respectively. One of these trials ended in a collision and this run exhibited a notably lower speed reduction when compared to the other trials. The third and fourth sets of trials included subject vehicle and lead vehicle initial velocity combinations of 75 and 35 km/h and 80 and 12 km/h, respectively, and contact was avoided in all trials. For the lead vehicle decelerating scenario collision was avoided for all trials during the 40 km/h test. Impact occurred during four out of five runs in the 50 km/h test with an initial headway of 18 m. However, at the longer headway lengths of 21, 23, 25, and 40 m there were no collisions during the 50 km/h tests. Additionally, contact was avoided for the 80 km/h test with headway lengths of 23, 25, 28, 40, and 45 m.

Table 11—2021 Freightliner Cascadia Test Track Scenarios

Scenario

Lead vehicle

speed

(km/h)

Subject vehicle

speed

(km/h)

Lead Vehicle Stopped

20-95

Lead Vehicle Moving

30-90

Lead Vehicle Moving

Lead Vehicle Decelerating

2021 Ram 5500

The class 5 2021 Ram 5500 was tested under the lead vehicle stopped, lead vehicle moving, and lead vehicle decelerating scenarios at the NHTSA VRTC in 2022. The tests performed for these scenarios involved no manual brake application; and the GVT was used as the lead vehicle. For the lead vehicle stopped scenario, the Ram truck avoided collisions at 10, 20, 30, 40 km/h, while impact occurred during two of the five trials in the 50 km/h test, although there was an approximately 80 percent reduction in speed. In general, these results seemed to align with limitations described in the vehicle owner's manual that indicated that the system works up to 50 km/h. Testing up to 80 km/h was not completed to avoid damage to the subject vehicle and test equipment. During the lead vehicle moving scenario, the truck avoided contact at 30, 40, 50, 60, 70, and 80 km/h. Impact did occur at 90 km/h, though there was a speed reduction of 63 percent. At 50 km/h, the lead vehicle decelerating scenario resulted in consecutive impacts with some speed reduction. Due to the repeated collisions, testing was discontinued to prevent damage to the subject vehicle and the GVT.

NHTSA also tested The Ram 5500 under the three scenarios with manual brake application. The lead vehicle stopped scenario resulted in avoidance of contact for all trials at 30, 40, and 60 km/h. Collision did occur at 50 km/h, though there was a speed reduction of approximately 80 percent. The lead vehicle moving scenario resulted in impact avoidance for all 40 to 90 km/h trials, but impact did occur during the 100 km/h test. For the lead vehicle decelerating scenario, impact occurred during the 50 km/h test with an initial headway of 40, 32, and 23 m. Collision also occurred for the 80 km/h test with a headway of 40 m.

Table 12—2021 Ram 5500 Test Track Scenarios

Scenario

Lead vehicle

speed

(km/h)

Subject vehicle

speed

(km/h)

Lead Vehicle Stopped

10-60

Lead Vehicle Moving

30-100

Lead Vehicle Decelerating

In general, no single vehicle avoided collisions at all speeds in the tested scenarios. While one vehicle may have performed better at lower speeds and the other better at higher speeds, the combination of results from the individual vehicles showed positive results over a range of speeds. Overall, the performance demonstrated that the AEB technology has improved over time, as shown in Tables 13 and 14.

71 72 73 74

Phase 1—Boday, C., et al., “Class 8 Truck-Tractor and Motorcoach Forward Collision Warning and Automatic Emergency Braking Test Track Research—Phase I,” Washington, DC: National Highway Traffic Safety Administration (June 2016). Docket No. NHTSA‐2015-0024-0004.

Phase II- U.S. DOT/NHTSA- Class 8 Truck- Tractor and Motorcoach Forward Collision Warning and Automatic Emergency Braking System Test Track Research- Draft Report. Docket No. NHTSA-2015-0024-0006.

Phase III—Salaani, M.K., Elsasser, D., Boday, C., “NHTSA's 2018 Heavy Vehicle Automatic Emergency Braking Test Track Research Results,” SAE International. J Advances & Current Practices in Mobility 2(3):1685-1704, 2020, doi:10.4271/2020-01-1001.

This information is available in the report titled “NHTSA Heavy Vehicle AEB Test Track Performance Data Summary Report—2022,” placed in the docket identified in the heading of this NPRM.

Table 13—Technology Improvement Over Time

[Class 7-8]

Class 7-8 heavy vehicle capability

1st period—

introduction

2nd period—2nd

generation

(2015)

Current

(2022)

FCW and AEB activate for moving vehicles

Yes

Yes.

AEB can avoid contact at test speeds up to 80 km/h in lead vehicle moving scenarios

Yes

Yes.

AEB can avoid contact at test speeds greater than 80 km/h in lead vehicle moving scenarios

N/A

Yes.

FCW alerts for stopped vehicles

Yes

Yes.

AEB activates for stopped vehicles

Yes

Yes.

AEB can avoid contact at test speeds up to 80 km/h in lead vehicle stopped scenarios

Yes.

AEB can avoid contact at test speeds greater than 80 km/h

Yes.

Table 14—Technology Improvement Over Time

[Class 3-6]

Class 3-6 heavy vehicle AEB capability

Up to 2015

2016-2022

FCW and AEB activate for moving vehicles

Yes

Yes.

AEB can avoid contact at test speeds up to 80 km/h in lead vehicle moving scenarios

Yes.

AEB can avoid contact at test speeds greater than 80 km/h in lead vehicle moving scenarios

Yes.

FCW alerts for stopped vehicles

Yes

Yes.

AEB activates for stopped vehicles

Yes.

AEB can avoid contact at test speeds up to 80 km/h in lead vehicle stopped scenarios

No.

AEB can avoid contact at test speeds greater than 80 km/h

No.

C. NHTSA Field Study of a New Generation Heavy Vehicle AEB System

NHTSA has an ongoing field study with VTTI that aims to collect naturalistic driving data of at least 150 heavy vehicles over a one-year timeframe. The goal is to collect data from each driver participant for a three-month segment of the year. This research has very similar parameters and objectives as those described above for the “Field Study of Heavy-Vehicle Crash Avoidance Systems” study. However, several years have elapsed since the data were collected for the prior study; and the trucks included in this ongoing research project are equipped with newer generation AEB systems, including stationary object braking and system integration into instrument clusters.

The data acquisition systems installed on the heavy vehicles will allow VTTI to sample various system activations including AEB, stationary object alerts and FCWs. The focus of the study's real-world data collection and analysis is to ascertain an understanding of vehicle performance, driver behavior, and driver adaptation. VTTI is evaluating Bendix Commercial Vehicle Systems and Detroit Assurance (Daimler) systems and the five objectives include evaluation of system reliability, assessment of driver performance over time, assessment of overall driving behavior, collection of data on real-world conflicts, and generation of inputs to a safety benefits simulation model.

Preliminary results from the driver survey responses indicate that many drivers agree that collision mitigation technology makes drivers safer. Approximately 50 percent of drivers surveyed at least slightly agree that AEB is beneficial and helps drivers avoid a crash.

This information is available in a report titled “HV AEB Driver Exit Survey Summary as of August 31, 2022,” which has been placed in the docket for this rulemaking.

V. Need for This Proposed Rule and Guiding Principles

A. Estimating AEB System Effectiveness

In developing this NPRM, NHTSA has examined the effectiveness of AEB, proposing only those amendments that contribute to improved crash safety, and have considered the principles for regulatory decision-making set forth in Executive Order 12866 (as amended), Regulatory Planning and Review.

The effectiveness of AEB indicates the efficacy of the system in avoiding a rear-end crash. This NPRM proposes to require heavy vehicles to have AEB systems that enable the vehicle to completely avoid an imminent rear-end collision under a set of test scenarios. One method of estimating effectiveness would be to perform a statistical analysis of real-world crash data and observe the differences in statistics between heavy vehicles equipped with AEB and those not equipped with AEB. However, this approach is not feasible currently due to the low penetration rate of AEB in the on-road vehicle fleet. Consequently, NHTSA estimated effectiveness of AEB systems using performance data from the agency's vehicle testing. The agency assessed effectiveness against all crash severity levels collectively, rather than for specific crash severity levels (

i.e.,

minor injury versus fatal).

The performance data derived from four different test vehicles was used to estimate AEB effectiveness,

and the agency is continuing its effort to test a larger variety of vehicles to further evaluate AEB system performance. These vehicles were subject to the same test scenarios (stopped lead vehicle, slower-moving lead vehicle, decelerating lead vehicle) that are proposed in this NPRM, and effectiveness estimates are based on each vehicle's capacity to avoid a collision during a test scenario. For example, if a vehicle avoided colliding with a stopped lead vehicle in four out of five test runs, its effectiveness in that scenario would be 80 percent. The test results for each vehicle were combined

This information is available in the report titled “NHTSA Heavy Vehicle AEB Test Track Performance Data Summary Report—2022,” placed in the docket identified in the heading of this NPRM.

into an aggregate effectiveness value by vehicle class range and crash scenario, as displayed in Table 15.

Table 15—AEB Estimated Effectiveness (Percent)

[By vehicle class range and crash scenario]

Vehicle class range

Stopped lead

vehicle

Slower-moving

lead vehicle

Decelerating

lead vehicle

7-8

38.5

49.2

3-6

43.0

47.8

As shown in Table 15, after aggregating class 7 and class 8 together, the agency has estimated AEB would avoid 38.5 percent of rear-end crashes for the stopped lead vehicle scenario, and 49.2 percent of slower-moving and decelerating lead vehicle crashes. For class 3-6, AEB is estimated to be 43.0 percent effective against stopped lead vehicle crashes and 47.8 percent against slower-moving and decelerating lead vehicle crashes. These effectiveness values are the values NHTSA used for assessing the benefits of this proposed rule.

B. AEB Performance Over a Range of Speeds Is Necessary and Practicable

The performance requirements proposed in this NPRM are designed around the goal of realizing as much of the safety potential of AEB systems, while remaining realistic and practicable both economically and technically. AEB performance guidelines created outside of the agency's rulemaking process appear not to have been created with these same goals, and thus may not represent the optimal balance of safety and practicability. Several AEB performance tests developed in the private sector are limited to a maximum test speed of around 40 km/h (25 mph), and do not test the capability of AEB system at highway speeds.

77 78

IIHS Autonomous Emergency Braking Test Protocol (Version I). Available at

https://www.iihs.org/media/a582abfb-7691-4805-81aa-16bbdf622992/REo1sA/Ratings/Protocols/current/test_protocol_aeb.pdf.

(last accessed August 5, 2022).

SAE International Forward Collision Warning and Mitigation Vehicle Test Procedure—Truck and Bus J3029_201510. (For more details, see

https://www.sae.org/standards/content/j3029_201510

) (last accessed August 5, 2022).

NHTSA considered two primary factors in selecting the proposed test speed ranges. The first factor is the practical ability of AEB technology to consistently operate and avoid contact with a lead vehicle at the widest reasonable range of speeds. A larger range of speeds would likely yield more safety benefits and would more thoroughly test the capabilities of the AEB system. Furthermore, as observed in vehicle testing for NHTSA research, AEB performance during testing at higher speeds does not necessarily indicate what the same system's performance will be at lower speeds. For example, NHTSA's testing of the 2021 Freightliner Cascadia truck showed that the AEB system was able to avoid a collision with the lead vehicle at test speeds of 40 to 85 km/h, but not at speeds below 40 km/h. Thus, testing over a range of speeds is necessary to more fully assess AEB performance.

This information is available in the report titled “NHTSA Heavy Vehicle AEB Test Track Performance Data Summary Report—2022,” placed in the docket identified in the heading of this NPRM.

The second factor is the practical limit of safely conducting vehicle tests of AEB systems. Test data indicates that AEB performance is less consistent, becoming less likely to avoid a collision when test speeds approach or exceed the proposed upper limits, indicating that testing at higher speeds than proposed would be beyond technological feasibility.

More detail on test data is discussed in the NHTSA and FMCSA Research and Testing section.

NHTSA's testing must be safe and repeatable as permitted by track conditions and testing equipment. For example, if the AEB system does not interv

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