Federal Motor Vehicle Safety Standards; Pedestrian Head Protection, Global Technical Regulation No. 9; Incorporation by Reference

Federal RegisterSep 19, 2024

Ask Donna

What actually matters in this document.

Text

DEPARTMENT OF TRANSPORTATION

National Highway Traffic Safety Administration

49 CFR Part 571

[Docket No. NHTSA-NHTSA-2024-0057]

RIN 2127-AK98

Federal Motor Vehicle Safety Standards; Pedestrian Head Protection, Global Technical Regulation No. 9; Incorporation by Reference

AGENCY:

National Highway Traffic Safety Administration (NHTSA), Department of Transportation (DOT).

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

NHTSA proposes a new Federal Motor Vehicle Safety Standard (FMVSS) that would ensure passenger vehicles with a gross vehicle weight rating (GVWR) of 4,536 kilograms (kg) (10,000 pounds (lb)) or less are designed to mitigate the risk of serious to fatal injury in child and adult pedestrian crashes. The proposed standard would establish test procedures simulating a head-to-hood impact and performance requirements to minimize the risk of head injury. This NPRM is based on a Global Technical Regulation (GTR) on pedestrian protection, with focused enhancements to address safety problems and a regulatory framework unique to the United States.

DATES:

Comments must be received on or before November 18, 2024.

Proposed compliance date:

The first September 1, two (2) years following the date of publication of any final rule in the

Federal Register

, with optional early compliance permitted. Final-stage manufacturers and alterers would be provided an additional year to comply.

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.

Regardless of how you submit your comments, please mention 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.

Docket:

For access to the docket to read background documents or comments received, go to

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:

For non-legal issues: Vincent Wu, Office of Crashworthiness Standards (telephone: (202) 366-1740, fax (202) 493-2990). For legal issues: Matthew Filpi, Office of the Chief Counsel (telephone: 202-366-3179). The mailing address for these officials is: National Highway Traffic Safety Administration, 1200 New Jersey Avenue SE, Washington, DC 20590.

SUPPLEMENTARY INFORMATION:

Table of Contents

I. Executive Summary

A. This Proposed Standard

B. Potential Impacts of the Rulemaking

II. Safety Need

III. Foundations of the Proposal

IV. The Global Technical Regulation

A. Introduction

B. GTR 9

C. Further Observations About the Differences Between This NPRM and the GTR

V. Approach of the Proposed Standard

A. Overview

B. Relevance to the Involved Vehicles

C. Advantages of Headform Component Tests

D. Head Injury Criterion (HIC)

E. Speed and Angle at Which the Headforms Would Impact the Hood

VI. Defining the Relevant Areas Subject to the Standard

A. Determining the Hood Top

B. Hood Area

C. Defining the Child Headform Test Area and the Adult Headform Test Area

VII. Proposed Requirements and Assessing Compliance

A. Amount of Hood Area That Must Conform to HIC 1000

B. Manufacturer Designations of HIC1700 Areas

C. First Point of Contact

D. Consideration Related to the Amount of Test Area That Must Meet the HIC100 and HIC1700 Limits

E. Considerations for Expansion of Test Area When It Is Less Than Two Thirds of the Numerical Value of the Hood Area

VIII. GTR 9 Terminology and Amendment 3

A. Comparison of Terminology

B. Amendment 3

IX. Headform Characteristics

A. General

B. Qualification Limits

C. Repeatability and Reproducibility

X. Other Issues

A. Active Hoods

XI. Effect on Other Standards

XII. Proposed Lead Time

XIII. Benefits and Costs

XIV. Considered Alternatives

XV. Rulemaking Analyses and Notices

XVI. Public Participation

I. Executive Summary

Improving pedestrian safety is a high priority of the Department of Transportation. Data show pedestrian fatalities increasing substantially in recent years. NHTSA issues this NPRM in an effort to address this safety problem. This NPRM proposes a new Federal Motor Vehicle Safety Standard (FMVSS) that would ensure that passenger vehicles are designed to reduce the risk of serious to fatal child and adult head injury in pedestrian crashes. This rulemaking initiates the process of adopting a Global Technical Regulation (GTR) on pedestrian protection as an FMVSS, with focused enhancements to the GTR to address safety problems and a regulatory framework unique to the U.S. In addition, this NPRM furthers the goals and policies of DOT's January 2022 National Roadway Safety Strategy, which describes the five key objectives of the Department's Safe System Approach: safer people, safer roads, safer vehicles, safer speeds, and post-crash care.

New Federal Motor Vehicle Safety Standard No. 228,

Pedestrian head protection,

would apply to passenger cars, light trucks (including pickups), multipurpose passenger vehicles (MPVs) (MPVs include sport utility vehicles (SUVs), crossover vehicles and vans) and buses with a GVWR of 4,536 kg (10,000 lb) or less. The standard would require vehicles to meet a head injury criterion (HIC) when subjected to testing simulating a head-to-hood impact. The vehicles would have to reduce the risk of serious to fatal head injury to child and adult pedestrians in impacts at vehicle speeds up to 40 km/h (25 mph), which encompass about 70 percent of pedestrian injuries from vehicle impacts. Moreover, it is expected the standard would be beneficial even at higher speeds.

This

NPRM advances NHTSA's objective of adopting a motor vehicle crashworthiness safety standard to ensure that passenger vehicles are designed to mitigate the risk of serious to fatal child and adult pedestrian head injury.

Hu, J., Lin, Y.-S., Boyle, K., Bonifas, A., Reed, M.P., Gupta, V., & Lin, C.H. (2023, November).

Pedestrian safety: assessment of crashworthiness test procedures

(Report No. DOT HS 813 518). National Highway Traffic Safety Administration.

This NPRM is part of a multi-step approach to enhance vehicle performance against pedestrian injury. First, it initiates the process of adopting Global Technical Regulation No. 9 (GTR 9), “Pedestrian safety,” into the Federal safety standards. NHTSA has collaborated with governments internationally to develop GTR 9, and numerous countries have adopted the GTR into their regulations. FMVSS No. 228 would establish a pedestrian standard domestically, to ensure that all vehicles with a GVWR of 4,536 kg (10,000 lb.) or less manufactured in or imported into the United States—including a sub-group of light trucks (large pickups and large SUVs) more common in the U.S. than in other parts of the world—mitigate the risk of serious head injury to pedestrians.

Second, the standard would provide a regulatory counterpart to NHTSA's planned crashworthiness pedestrian protection testing program in the New Car Assessment Program (NCAP) in the near term.

On May 26, 2023, NHTSA published an NCAP Request for Comment (NCAP RFC) proposing to adopt a crashworthiness pedestrian protection program into NHTSA's NCAP.

NCAP would build on proposed FMVSS No. 228 and incorporate enhanced crashworthiness tests into NCAP that go beyond the specifications of proposed FMVSS No. 228. NCAP remains a consumer information program that provides consumers with vehicle safety information for their purchasing decisions. Providing this information encourages manufacturers to voluntarily make changes to vehicles that reflect positively in the NCAP safety information and thereby improves safety through the marketplace. FMVSSs, on the other hand, are mandatory and mandate at least a minimum level of safety that all new vehicles

must

provide to

every

purchaser. NHTSA has observed that, in the case of both electronic stability control and rear visibility cameras, only approximately 70 percent of vehicles had these technologies during the time they were part of NCAP. Thus, while NCAP serves a vital safety purpose, NHTSA also recognizes its limitations in ensuring that every vehicle provides the performance necessary to provide the requisite level of safety to all purchasers. Because only an FMVSS can ensure that all vehicles are equipped with technologies and vehicle designs that meet the specified performance requirements, NCAP can supplement but not substitute for the FMVSS. The FMVSS remains NHTSA's core way of ensuring that all motor vehicles provide the requisite level of safety performance, and provide it within a practicable timeframe. Although the NCAP program provides valuable safety-related information to consumers in a simple and easy-to-understand manner, the agency believes that the proposed rule is necessary to achieve the highest level of pedestrian safety feasible and at the fastest achievable timeframe based on the performance requirements and lead time specified in the proposed rule. Additional discussion on the NCAP RFC is provided later in this preamble.

NHTSA has proposed a roadmap for the agency's plans to upgrade NCAP in phases over the next several years. 87 FR 13452, March 9, 2022, extension of comment period, 87 FR 27200.

88 FR 34366, May 26, 2023. The proposed NCAP pedestrian protection program would incorporate crashworthiness tests similar to those used by the European New Car Assessment Programme (Euro NCAP). Euro NCAP's tests are closely aligned with those in GTR 9.

Third, this rulemaking proposing FMVSS No. 228 is intended to work hand-in-hand with the growth and expansion of automatic emergency braking (AEB) technologies. An AEB system uses various sensor technologies and sub-systems that work together to detect when the vehicle is in a crash imminent situation, to automatically apply the vehicle brakes if the driver has not done so, or to apply more braking force to supplement the driver's braking. AEB systems were originally developed to detect a crash imminent situation with a lead vehicle, but AEB is in a state of rapid advancement and some of the systems on the market now also warn about, and respond to, an imminent collision with a pedestrian. Pedestrian AEB (PAEB) systems are designed to stop the vehicle automatically before striking a pedestrian or reduce the speed at which an impact occurs if the vehicle's initial speed is too high to avoid impact. On May 9, 2024, NHTSA published a final rule requiring AEB and PAEB systems on light vehicles which adopts FMVSS No. 127.

FMVSS No. 127 builds on a voluntary commitment, announced by NHTSA in March 2016, by 20 vehicle manufacturers to make lead-vehicle AEB a standard feature on light vehicles, though that commitment did not include PAEB.

When new vehicles are equipped with PAEB, we anticipate that fewer pedestrians will be struck. For some impacts that cannot be avoided due to the closing speed of the vehicle (the relative speed between the vehicle and what it is approaching, in this case, the pedestrian), PAEB will lower the vehicle's speed so more impacts will be at speeds of 40 km/h (25 mph) or less, which is the velocity range FMVSS No. 228 is designed to replicate. FMVSS No. 228 would address those crashes and ensure the vehicles mitigate the risk of serious to fatal head injury in these impacts.

PAEB will eliminate many pedestrian impacts and reduce the impact of those crashes that do occur. This NPRM, if adopted, would further reduce the risk of serious injury or death from head injuries if a pedestrian strikes the hood of a vehicle. NHTSA has accounted for the effect of FMVSS No. 127 in estimating the economic impacts of this rulemaking.

88 FR 38632, Docket NHTSA-2023-0021. The NPRM applies to passenger vehicles with a GVWR of 4,536 kg (10,000 lb) or less. The action can also be found in the Unified Agenda of Regulatory and Deregulatory Actions, RIN 2127-AM37.

The 20 vehicle manufacturers represent more than 99 percent of the U.S. market. The commitment was to have AEB on virtually all (at least 95 percent) new passenger cars, light trucks, and MPVs with a GVWR of 8,500 pounds or less no later than September 1, 2022, and a standard feature on virtually all light trucks and MPVs with a GVWR between 8,501 pounds and 10,000 pounds no later than Sept. 1, 2025. Most manufacturers met the 2022 mark, but some did not (

https://www.iihs.org/news/detail/three-more-automakers-fulfill-pledge-to-make-autobrake-nearly-universal

). Other agency data indicate about 87% of production has PAEB.

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

The voluntary commitment did not involve a pedestrian AEB component. NHTSA's NPRM would require an AEB system that detects and reacts to both lead vehicles and pedestrians and would increase the lead-vehicle performance required of AEB over that described in the voluntary commitment.

Yanagisawa, M., Swanson, E., Azeredo, P., & Najm, W.G. (2017, April). Estimation of potential safety benefits for pedestrian crash avoidance/mitigation systems. (Report No. DOT HS 812 400). Washington, DC: National Highway Traffic Safety Administration.

https://www.nhtsa.gov/sites/nhtsa.gov/files/documents/812400_pcambenefitsreport.pdf.

This NPRM proposes FMVSS No. 228 and aligns with the goals of DOT's January 2022 National Roadway Safety Strategy, which describes the five key objectives of the Department's Safe System Approach: safer people, safer roads, safer vehicles, safer speeds, and post-crash care. FMVSS No. 228 would mandate requirements for safer vehicles and leverage advanced crash avoidance technology like PAEB in conjunction with the crashworthiness countermeasures based on GTR 9 to realize far-reaching improvements to pedestrian safety. NHTSA also notes that although research into vulnerable

road users and vehicle safety measures has focused predominantly on improving the protection of pedestrians, several effectiveness studies have concluded that pedestrian safety measures like this NPRM's head protection requirements would also be beneficial for cyclists.

Simms CK and Wood DO (2009), Pedestrian and cyclist impact—a biomechanical perspective, Springer Science and Business Media, Dordrecht Heidelberg London New York; see Chapter 10: The influence of vehicle design on pedestrian and cyclist injuries.

Issuance of this NPRM is also consistent with the goals of the November 15, 2021, Infrastructure Investment and Jobs Act (IIJA).

Section 24211 of IIJA, “Global Harmonization,” states that the Secretary shall cooperate, to the maximum extent practicable, with foreign governments, nongovernmental stakeholder groups, the motor vehicle industry, and consumer groups with respect to global harmonization of vehicle regulations as a means for improving motor vehicle safety. This NPRM proposes to adopt an FMVSS for pedestrian head protection founded on Global Technical Regulation No. 9, “Pedestrian Safety” (GTR 9). NHTSA collaborated with experts from around the world to develop GTR 9. Establishing an FMVSS based on a Global Technical Regulation aligns with the goals of IIJA Section 24211.

Public Law 117-58.

Although GTR 9 was established in 2008 when light trucks and vans (LTVs), which includes large light trucks, MPVs (including SUVs) and vans, were not as common as they are now in the U.S., LTVs did exist then, and the GTR test procedure included in proposed FMVSS No. 228 was developed to be relevant and applicable to these LTV vehicles. The test procedure proposed for use in FMVSS No. 228 is relevant for use with all light vehicles in the U.S. fleet because it is based on a Wrap Around Distance (WAD) measurement appropriate for use with passenger cars and LTVs. The defined “Hood Area” (subject to proposed FMVSS No. 228 coverage) is based on WAD, so any differences in head impact locations for a given crash scenario between LTVs and passenger cars are accounted for in the WAD-based test. As described in sections V.-VII., in the proposed test, NHTSA would use impactor testing to simulate a head-to-hood or head-to-fender top impact. It would specify the use of two different impactors: one representative of the head of a struck 6-year-old child (child headform) and another representative of the head of a struck 50th percentile adult male pedestrian (adult headform). The WAD measurement assures that the areas of the hood subject to impactor testing are the areas likely to be struck by a pedestrian's head. NHTSA has performed the WAD-based test of GTR 9 on a wide variety of vehicles, including LTVs of various shapes and sizes. These data have been used to generate the benefit-cost analysis for this NPRM, which NHTSA discusses in the Preliminary Regulatory Impact Analysis (PRIA) accompanying this NPRM. The PRIA, discussed in detail in sections below, calculates benefits and costs separately for passenger cars and LTVs.

Because the WAD-based test procedure of the GTR is technically suitable for small and large vehicles, this NPRM's regulatory text reflects the wording of GTR 9 to show the GTR's provisions implemented in a Federal motor vehicle safety standard. Throughout this preamble, however, NHTSA requests comments on the pros and cons of various aspects of the NPRM's regulatory text, particularly with respect to the areas of the vehicle that would be subject to headform testing strictly using the GTR procedure. Throughout this preamble, NHTSA focuses readers on ways NHTSA believes the proposed regulatory text could be enhanced in a final rule to achieve more safety benefits in the U.S. For example, we discuss an approach of potentially extending the test area to the grille area on all large vehicles where the head of a child or shorter adult pedestrian may be struck. With pedestrian injury and fatality rates climbing, and with lessons learned from NHTSA's NCAP and other NCAP programs engaged in headform testing of vehicle front ends, NHTSA seeks to design FMVSS No. 228 to be as effective as possible to address pedestrian safety needs in the U.S.

Accordingly, this NPRM discusses specific approaches that NHTSA is considering to possibly tailor the GTR text for a final rule. While the NPRM's regulatory text reflects the GTR's approaches and provides a framework for an FMVSS based on those provisions, NHTSA may determine to make changes in any final rule. Ultimately, NHTSA seeks to issue a final rule that would “fully meet the need in the U.S. for vehicle safety.”

Section I.B.1, 49 CFR part 553, appendix C, “Statement of Policy: Implementation of the United Nations/Economic Commission for Europe (UN/ECE) 1998 Agreement of Global Technical Regulations—Agency Policy Goals and Public Participation.”

A. This Proposed Standard

In collisions between vehicles and pedestrians, the pedestrian is typically struck from the side while walking across the vehicle's path. When a pedestrian is struck in this manner, the first point of contact typically occurs between the front-end of the vehicle and the lateral aspect of the pedestrian's leg near the knee region. As the lower leg becomes fully engaged with the vehicle's front-end, the leading edge of the hood strikes the lateral aspect of the pedestrian's pelvis or upper leg. Then, as the lower leg is kicked forward and away from the front-end of the vehicle, the pedestrian's upper body swings abruptly downward towards the hood until the head strikes the vehicle. Research indicates that the linear head impact velocity ranges between 60 and 110 percent of the initial contact velocity.

Mizuno K et al. (2001), Summary Of IHRA Pedestrian Safety WG Activities—Proposed Test Methods To Evaluate Pedestrian Protection Afforded By Passenger Cars.

Proposed FMVSS No. 228 is designed to mitigate injuries to pedestrians hit from the side as described above. Most pedestrian injuries (79%) and fatalities (83%) are caused by the frontal structures of vehicles.

Roughly two-thirds of these occur when vehicle travel speeds are less than 40 km/h (25 mph).

12 13

Crash data show that pedestrian head injuries occur due to contacts to all areas of vehicle front ends, including the hood.

14 15

The location the pedestrian's head strikes is dependent on the pedestrian's size, the front configuration of the vehicle, and the speed of impact. In a 40 km/h (25 mph) impact, roughly 15% of pedestrian fatalities involve the pedestrian's head contacting the Hood Top. This NPRM focuses on mitigating head injuries sustained from contacting the hood and adjacent areas around the hood on the vehicle front end.

See table II.1.

Rosen E, Sander U (2009) Pedestrian fatality risk as a function of car impact speed. Accident Analysis and Prevention, 2009;41:536-542.

Stammen JA et al (2002), A Demographic Analysis and Reconstruction of Selected Cases from the Pedestrian Crash Data Study, Paper No. 2002-01-0560, SAE International, Warrendale PA.

Yutaka Okamoto, Tomiji Sugimoto, Koji Enomoto & Junichi Kikuchi (2003), Pedestrian Head Impact Conditions Depending on the Vehicle Front Shape and Its Construction—Full Model Simulation, Traffic Injury Prevention, 4:1, 74-82, DOI: 10.1080/15389580309856.

Bahman S. Roudsari, Charles N. Mock & Robert Kaufman (2005) An Evaluation of the Association Between Vehicle Type and the Source and Severity of Pedestrian Injuries, Traffic Injury Prevention, 6:2, 185-192, DOI: 10.1080/15389580590931680.

Proposed FMVSS No. 228 would use impactor testing simulating a head-to-

hood or head-to-fender top impact.

It would specify the use of two different impactors: one with a mass of 3.5 kg that is representative of the head of a struck 6-year-old child (child headform) and another with a mass of 4.5 kg representative of the head of a struck 50th percentile adult male pedestrian (adult headform). The standard would define various areas of a test vehicle

hood (such as the Hood Top and Hood Area) subject to testing in an objective and repeatable manner. The Hood Area would be partially composed of the Child Headform Test Area and the Adult Headform Test Area. The area likely to be struck by a child pedestrian's head (the Child Headform Test Area) would be tested with the child headform and the area likely to be struck by an adult's head (the Adult Headform Test Area) would be tested with the adult headform.

The headforms would hit areas of the vehicle hood at specific speeds and impact angles replicating a real-world vehicle traveling at 40 km/h (25 mph) and impacting the adult or child pedestrian.

We note that the “hood” as defined in proposed FMVSS No. 228 would typically encompass portions of the fender top.

“Test vehicle” refers to the vehicle whose compliance with proposed FMVSS No. 228 is being assessed.

This preamble occasionally refers to these two test areas together as the “Child and Adult Headform Test Areas.”

The following figure generally depicts the areas of a vehicle that would be subject to FMVSS No. 228 testing, particularly the Hood Top and Hood Area (which share a boundary in this example and are contained within the dashed lines), and the Child and Adult Headform Test Areas (darkly shaded areas). The figure illustrates other terms and concepts used in the proposed standard. All of the terms used in the figure are fully explained in this preamble.

BILLING CODE 4910-59-P

EP19SE24.002

BILLING CODE 4910-59-C

Proposed FMVSS No. 228 would specify performance requirements limiting the accelerations measured by the headforms. The HIC must be less than 1000 (HIC1000) over a certain portion of the Child and Adult Headform Test Areas.

The requisite portions would be derived as a percentage of the overall Hood Area. Generally speaking, the portion of the Child Headform Test Area that must

meet the HIC1000 requirement must be at least one-half of the numerical value (numerical value of the area is calculated from a projection onto a horizontal plane) of the Hood Area below what is called the “WAD1700 line.”

Based on data showing the locations of child and adult head impacts, this NPRM proposes that WAD1700 would be the boundary between the Child Headform Test Area and the Adult Headform Test Area. Secondly, the portion of the Combined Child and Adult Headform Test Areas that must comply with the HIC1000 limit must be at least two-thirds of the numerical value of the Hood Area. Because hard areas under the hood are challenging to mitigate, for practicability reasons the HIC limit for the remaining test areas is higher, but nonetheless limited to HIC1700.

Injuries can be categorized according to the Abbreviated Injury Scale (AIS). AIS ranks individual injuries on a scale of 1 to 6: 1=minor, 2=moderate, 3=serious, 4=severe, 5=critical, and 6=maximum (untreatable). In previous rulemakings (notably with respect to those involving FMVSS No. 208 and FMVSS No. 214), NHTSA associated HIC1000 with an 11% risk of AIS 4+ brain injuries.

FMVSS No. 228 would have detailed procedures that define the areas on the hood, including a Wrap Around Distance (WAD) procedure that identifies various reference lines on the hood. As explained in a later section, in any particular vehicle vertical longitudinal plane, the Wrap Around Distance is the distance from a point on the ground directly below the vehicle's most forward edge in that plane, to a designated point on the hood, as measured with a flexible measuring device, such as a flexible wire. WADs of various lengths correlate to where pedestrians of different heights would hit their head on the hood when struck from the side. We can create a WAD line using wires of different lengths,

e.g.,

a wire of 1700 +/− 1 mm can be used to draw a line at 1,700 mm from the ground reference plane (such a line is referred to as WAD1700).

HIC1700 is associated with a 36% risk of AIS 4+ brain injuries.

To meet the HIC limits, hoods would be required to have protective countermeasures that attenuate the energy of the impact during initial contact of the headform, and/or that provide sufficient clearance (open areas) to prevent the headform from bottoming out on objects beneath the hood. The countermeasures would have to ensure that the hood is not too stiff (such a hood would fail the HIC requirement) and not too soft (a too soft hood could also fail because the headform could penetrate down to the level of a hard, immovable structure beneath the hood). Among other objectives, an effective design balances hood stiffness with depth of penetration.

Examples of elements of designs that are beneficial to pedestrian head protection are: introducing additional clearance between the inner and outer skins of the hood, using energy-absorbing materials to improve shock absorption, redesigning stiff structures under the hood, such as hinges and headlight frames, to crush, collapse, or shear off, and redesigning the side edges of the hood where it meets up with the fenders to use a more deformable support structure or moving the stiff hood-to-fender junction out of the head impact zone. “Active hoods” have also emerged that have a front-end sensor and lever arms to automatically lift (pop up) the hood upon detecting that a pedestrian has been struck. An actuator near the hinge pops the hood slightly to provide more space between the hood and rigid components in the engine bay.

B. Potential Impacts of the Rulemaking

FMVSS No. 228 would apply to passenger cars and to MPVs, trucks, and buses with a GVWR of 4,536 kg (10,000 lb) or less.

Due to the widespread adoption and use of GTR 9 by other countries, most passenger vehicles sold in the U.S. that use international platforms already incorporate the head protection designs of the GTR. Regardless of current voluntary conformance, we propose to adopt GTR 9 into an FMVSS to ensure future vehicles provide at least the pedestrian head protections voluntarily provided today. We also seek to address the many U.S. variants and other models built upon uniquely American platforms that may or may not be designed to the GTR requirements. This includes essentially the entire pickup truck and large SUV segments (about 22% of the U.S. passenger vehicle 2020 sales, according to data provided by Wards Automotive). Our testing indicates that it is possible for some pickup trucks to pass the headform HIC requirements,

which implies domestic implementation is feasible. This proposal would ensure that uniquely American platforms, such as pickups, would provide the proposed level of pedestrian head protection. In this NPRM, NHTSA also considers modifying some aspects of GTR 9 to clarify the wording of the regulation, improve objectivity, and potentially increase safety benefits resulting from the GTR's application to the U.S. fleet. NHTSA proposes a domestic FMVSS No. 228 to achieve those enhancements.

Consistent with the GTR, the proposed regulatory text includes a provision that excludes from the standard MPVs, trucks, and buses where the distance, measured longitudinally on a horizontal plane, between the transverse centerline of the front axle and the seating reference point of the driver's seat, is less than 1000 mm. However, we are considering applying FMVSS No. 228 to these vehicles and are requesting comment on this issue later in the preamble.

In headform testing of mid-2000 model year vehicles, large SUVs and pickups performed about the same as minivans, smaller SUVs, and passenger cars. For more details, see Mallory et al., (2007), Pedestrian GTR testing of current vehicles, ESV Paper No. Paper No. 07-0313. Among the vehicles tested were two pickups—a 2003 Dodge Ram and a 2005 Chevy Silverado—and neither had a head impact that exceeded the HIC limit in this NPRM.

This NPRM is economically significant under Executive Order 12866 due to the benefits estimated to result from the proposed standard. NHTSA's PRIA analyzes the potential impacts of proposed FMVSS No. 228. NHTSA has placed a copy of the PRIA in the docket for this NPRM.

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.

NHTSA estimates that the proposal would mitigate approximately 67.4 fatalities annually, even after accounting for the effect of PAEB. (However, as explained in detail in sections below, the count of

injuries

will increase as averted fatalities are replaced by injuries.) For passenger cars, the cost per vehicle is estimated to be in the range of $2.86-$3.50 when discounted at 3% and 7%. Similarly, LTVs have a per vehicle cost of $3.29-$4.08. When discounted at 3% and 7%, the total annual cost ranges from $48.94 to $60.43 million. The overall discounted equivalent lives saved (ELS) range from approximately 44.46 to 54.87. Taking into account both discount rates, the cost per ELS is $1.10 million and net benefits range from approximately $480.79 to $593.33 million. Table I.1 summarizes the cost and benefits for both discount rates. Additional details of the benefits and costs analysis can be found in section X.III of this preamble.

Table I.1—Summary of Cost and Benefits

[Millions]

Discount rate

Cost

Equivalent

lives saved

Cost per

equivalent

live saved

Monetized

benefits

Net benefits

$60.43

54.87

$1.10

$653.76

$593.33

48.94

44.46

1.10

529.74

480.79

II. Safety Need

In 2020, 38,824 people died on U.S. roads. Of this number, 25,536 were passenger vehicle occupant fatalities, a decrease from 32,225 in 2000.

This reduction is notable, particularly in light of the fact that the total number of vehicle miles traveled (VMT) in the U.S. has increased over time. However, during that same timeframe, pedestrian fatalities increased by 33 percent, from 4,739 in 2000 to 6,516 in 2020.

27 28

Traffic Safety Facts 2020 “

A Compilation of Motor Vehicle Crash Data.”

U.S. Department of Transportation. National Highway Traffic Safety Administration.

Traffic Safety Facts 2000 “

A Compilation of Motor Vehicle Crash Data from the Fatality Analysis Reporting System and the General Estimates System.”

U.S. Department of Transportation. National Highway Traffic Safety Administration.

National Center for Statistics and Analysis. (2021, October),

Early Estimate of Motor Vehicle Traffic Fatalities for the First Half (January-June) of 2021.

(Traffic Safety Facts. Report No. DOT HS 813 199), Washington, DC: National Highway Traffic Safety Administration.

The vast majority of pedestrian fatalities (98% or 6,132) are due to a single striking vehicle.

A 2019 NHTSA report analyzed the critical events or actions related to crashes (

e.g.,

control loss, road departure), including the critical event of striking a pedestrian.

The report found that an average of 3,731 fatal crashes and a total of 70,461 crashes each year included the critical event of a vehicle striking a pedestrian (years 2011-2015). This represents 53 fatal crashes per thousand crashes, the highest among any critical events tabulated.

NHTSA Fatality Analysis Reporting System (FARS).

Swanson, E., Foderaro, F., Yanagisawa, M., Najm, W.G., & Azeredo, P. (2019, August). Statistics of light-vehicle pre-crash scenarios based on 2011-2015 national crash data (Report No. DOT HS 812 745). Washington, DC: National Highway Traffic Safety Administration.

Most injuries resulting from collisions between vehicles and pedestrians are inflicted by the frontal structures of vehicles, the majority of which occur when vehicle travel speeds are lower than 40 km/h (25 mph) (see figure V.2). Pedestrians sustaining life-threatening injuries typically have head and thorax injuries caused by contact with the vehicle. A NHTSA study using both U.S. and German crash data found that the head and lower extremities are the most common injury locations on a struck pedestrian.

The head, legs, and thorax are the most common locations for serious injury, and the head, legs, and pelvis/hip are the most common locations for disabling injuries. A NHTSA study analyzing the potential effect of the head, upper leg and lower leg component test procedures estimated that among serious to fatal injury cases (MAIS

3+), 37.8 percent of the total expected potential effects of the test procedures was associated with the headform test, 24.6 percent was associated with the upper legform test and 37.6 percent was associated with the lower legform test. When the analysis was limited to more severe injuries (MAIS 4+ or fatal cases), the influence of the headform test was substantially higher, while the relative influence of the upper legform and lower legform tests was reduced.

Mallory, A., Fredriksson, R., Rosen, E., Donnelly, B. (2012, October). Pedestrian Injuries By Source: Serious and Disabling Injuries in US and European Cases. 56th AAAM Annual Conference.

MAIS stands for Maximum Abbreviated Injury Scale.

Mallory, A., Yarnell, B., Kender, A., & Stammen, J. (2019, May). Relative frequency of U.S. pedestrian injuries associated with risk measured in component-level pedestrian tests (Re-port No. DOT HS 812 658). Washington, DC: National Highway Traffic Safety Administration.

Studies have found a high prevalence of five crash types in collisions between vehicles and pedestrians.

These crash types are:

Snyder and Knoblauch (1971); Hunter WW et al. (1995), Pedestrian and Bicycle Crash Types; DaSilva MP et al., (2003), Analysis of Pedestrian Crashes, Report No. DOT HS 809 585, April 2003, Washington DC, NHTSA; Thomas L et al. (2014), North Carolina pedestrian crash types, 2008-2012, University of North Carolina Highway Safety Research Center, March 2014.

• Dart-out (first half)—where the pedestrian appears suddenly midblock, often from between parked cars, presents a limited exposure time to the driver and is struck less than halfway across the roadway.

• Dart-out (second half)—similar to the Dart-out (first half) except the pedestrian is struck after crossing half or more of the roadway.

• Intersection dash—where the pedestrian presents a short time exposure to the driver at an intersection either because the pedestrian runs across the intersection, is blocked from view, or crosses unexpectedly.

• Multiple threat—where a vehicle stops for a crossing pedestrian and, in so doing, blocks the pedestrian from the view of the driver in a second car that is overtaking the first car (includes intersection and midblock situations).

• Vehicle turn/merge—where the driver is concentrating on turning into or merging with traffic and does not see the pedestrian.

New Federal Motor Vehicle Safety Standard No. 228,

Pedestrian head protection,

(FMVSS No. 228) has proposed test procedures designed to replicate head-to-hood contact in the crash sequences described above. The procedures replicate a child or adult pedestrian crossing a street and being struck from the side by a vehicle travelling at a speed approaching 40 km/h (25 mph).

FMVSS No. 228 would affect vehicles involved in the majority of fatal pedestrian crashes: passenger cars, light trucks (pickups), and MPVs (vans, crossover vehicles and SUVs) (see table II.1). Sales are trending toward more non-passenger cars. Light trucks and MPVs as a percentage of light vehicle sales have steadily increased from 52% in 2011 to 77% in 2020.

Wards Automotive.

In a pedestrian crash, the vehicle striking the pedestrian is usually the only vehicle involved; the vast majority are single vehicle collisions in which the vehicle-to-pedestrian collision is the only harmful event. For fatalities, of front end striking vehicle types, there is about an even split between passenger cars (43 percent) and light trucks and MPVs (42 percent). Large trucks (GVWR greater than 4,536 kg (10,000 lb)), which are not covered by this proposal, are responsible for 6 percent of fatal front end to pedestrian strikes. Buses (covered by this NPRM only if they have a GVWR of 4,536 kg (10,000 pounds) or less) are responsible for 0.5 percent of fatal strikes and the remaining fatal strikes (8 percent) are caused by unknown vehicle types. The percentages for non-fatal injuries show a different distribution, with passenger cars representing 58 percent of front end striking vehicles and light trucks representing 40 percent.

Table II.1—Pedestrian Injuries and Fatalities in Single Vehicle Front End Crashes by Vehicle Type, 2020

Class of vehicle

Injuries

Fatalities

Passenger car

23,158 (58%)

38,961 (98%)

1,972 (43%)

3,941 (85%)

Light Truck and MPV

15,803 (40%)

1,969 (42%)

Large Truck

274 (6%)

Bus

21 (0.5%)

Unknown/other

959 (2%)

386 (8%)

Totals (front end)

39,921 (100%)

4,622 (100%)

Totals (all impact locations)

50,397

5,536

Sources: NHTSA's Fatal Accident Reporting System (FARS) and National Automotive Sampling System—General Estimates System (GES). NHTSA's Traffic Safety Facts Sheet.

In 2020, of all motor-vehicle related fatalities and injuries (including drivers, passengers, pedestrians, etc.) pedestrians accounted for 16 percent of all fatalities and 4 percent of injuries in the under 16 age group; pedestrians accounted for 12 percent of all motor vehicle-related fatalities and 2 percent of injuries in the age group 16-34; and pedestrians accounted for 19 percent of fatalities and 3 percent of injuries in the age group 35-44. For the age groups of 45-64 and 65 and older, the fatality figures were 21 percent and 18 percent, respectively. Injuries for these two groups were both 3 percent.

Table II.2—Pedestrians as a Percentage of All Traffic Fatalities and Injuries in 2020 by Age Group

Years old

Percent of

traffic fatalities

Percent of

traffic injuries

15 and Under

16-34

35-44

45-64

65 and Over

Sources: FARS and GES.

This proposal addresses the injuries and fatalities resulting from head impacts to the front of the vehicle. The derivation of the target population is described in detail in the PRIA accompanying this proposal. A summary of the PRIA is contained in section XIII of this proposal.

III. Foundations for the Proposal

NHTSA protects pedestrians through rulemaking, consumer information provided by the agency's New Car Assessment Program, safety research, and public education programs to improve safe driving and walking practices.

With respect to rulemaking, a number of vehicle standards have been issued for pedestrian safety, such as FMVSS No. 111 (49 CFR 571.111), which has rear visibility requirements that manufacturers must meet through backup cameras, and which requires outside rearview mirrors and their mountings to be free of sharp points or edges that could injure pedestrians. FMVSS No. 131 (49 CFR 571.131) applies to school bus stop arms that control traffic around children boarding or unloading from school buses. NHTSA recently amended FMVSS No. 108 (49 CFR 571.108) to permit the installation of adaptive driving beam requirements that help to improve roadway illumination so drivers can more easily detect pedestrians and motorcyclists.

NHTSA additionally expects that FMVSS No. 127, recently published final rule requiring PAEB, would have substantial benefits in preventing collisions with pedestrians and reducing the speed of impacts.

https://www.nhtsa.gov/road-safety/pedestrian-safety.

87 FR 9916; February 22, 2022.

NHTSA's Efforts on a Pedestrian Head Protection Standard

Over many years, NHTSA has studied the feasibility of additional countermeasures to reduce the severity of pedestrian leg, upper body, and head injuries. In 1981, NHTSA issued an NPRM

to limit the amount of force that may be exerted by a striking vehicle's bumper area on an adult pedestrian's lower leg in a 32.2 km/h (20 mph) crash. The rulemaking was later terminated when the potential countermeasure (a softer bumper) did not prove practicable.

A decade later, NHTSA had plans for an NPRM for head impact protection but discontinued regulatory work in that area at that time.

46 FR 7015; January 22, 1981.

69 FR 14496, April 10, 1991.

NHTSA held a public meeting on August 20, 1991, to seek public input on the agency's plans for a pedestrian protection regulation. Only the hood requirements were discussed at this meeting. In response to NHTSA's pedestrian safety plan presented at the meeting, all motor vehicle manufacturers indicated at least some major redesign would be required to meet the headform requirements. Based on such comments, unknowns about the benefits projected, the high costs of major vehicle redesign, and several other factors (such as international harmonization, pedestrian behavior enforcement, better infrastructure, and other crash avoidance measures), the agency did not proceed with the head impact protection rulemaking.

NHTSA, however, continued its research into child and adult pedestrian protection. The agency collaborated closely with other countries to harmonize international procedures and requirements,

and carried out key pedestrian research and data collection with international stakeholders such as the International Organization for Standards (ISO),

the International Harmonization of Research Activities (IHRA),

the European Commission

(E.C.), and the European Enhanced Vehicle Safety Committee (EEVC).

NHTSA was a key contributor to the development of Global Technical Regulation No. 9 (GTR 9) for pedestrian protection. This NPRM proposes to incorporate GTR 9 into a new FMVSS No. 228, to include pedestrian crashworthiness head protection requirements in the FMVSS for the first time.

61 FR 58362, November 14, 1996.

ISO is a worldwide standards-setting organization to facilitate the international exchange of goods and services.

IHRA was an inter-governmental steering committee formed to facilitate multi-national collaboration in research in major problem areas of road safety, including pedestrian safety. The IHRA expert group on pedestrian safety developed test

procedures to assess the vehicle-to-pedestrian collision.

The EEVC does not set standards or enforce regulations and is not a part of the European Commission (E.C.). The EEVC can only recommend safety standards to the E.C. and other legislative states, which may or may not develop them into regulations. The EEVC carries out auto safety research in a number of specialized areas called “Working Groups.” Research within a Working Group, overseen by a steering committee of representatives from Europe's national governments, is carried out by nominated technical experts who may also work for the automotive industry. Funding for EEVC research is typically provided as “in-kind” contributions from the groups represented by the steering committee members and technical experts.

IV. The Global Technical Regulation

A. Introduction

On June 25, 1998, the U.S. became the first signatory to the “Agreement Concerning the Establishing of Global Technical Regulations for Wheeled Vehicles, Equipment and Parts which can be Fitted and/or be Used on Wheeled Vehicles,” commonly referred to as the 1998 Agreement.

The 1998 Agreement was negotiated under the auspices of the United Nations Economic Commission for Europe (UNECE) under the leadership of the U.S., the European Community (EC) and Japan. The 1998 Agreement provides for the establishment of global technical regulations (GTRs) regarding the safety, emissions, energy conservation and theft prevention of wheeled vehicles, equipment and parts.

The 1998 Agreement is administered by the UN Economic Commission for Europe's World Forum for the Harmonization of Vehicle Regulations (WP.29).

https://www.unece.org/fileadmin/DAM/trans/main/wp29/wp29wgs/wp29gen/wp29glob/globale.pdf.

The 1998 Agreement entered into force on August 25, 2000.

By establishing GTRs under the 1998 Agreement, governmental organizations (Contracting Parties) seek to harmonize motor vehicle regulations at the regional and national levels.

Under the 1998 Agreement, Contracting Parties voting in favor of establishing a GTR are obligated to “submit the technical Regulation to the process” used in the country to adopt the requirement into the agency's law or regulation.

In the United States, that process usually commences with an NPRM, Advance NPRM (ANPRM), or Request for Comment. Under the terms of the 1998 Agreement, contracting parties are

not

obligated to adopt the GTR after initiating this process.

The 1998 Agreement recognizes that governments should have the authority to determine whether the GTR meets their safety needs.

Non-governmental organizations may also participate in a consultative capacity in groups developing GTRs. Manufacturers may participate through non-governmental organizations representing industry. Individual manufacturers may also provide input to the process.

Article 7, 1998 Agreement.

Id.

In deciding whether to adopt a GTR as an FMVSS, NHTSA follows the applicable procedural and substantive requirements for rulemaking, including the Administrative Procedure Act, the National Traffic and Motor Vehicle Safety Act (Safety Act) (49 U.S.C. 301), Presidential executive orders, and DOT and NHTSA policies, procedures and regulations.

Under § 30111(a) of the Safety Act, Federal Motor Vehicle Safety Standards must be practicable, meet the need for motor vehicle safety, and be stated in objective terms.

Section 30111(b) states that, when prescribing such standards, NHTSA (by delegation at 49 CFR 1.95) must, among other things, consider all relevant, available motor vehicle safety information, consider whether a standard is reasonable, practicable, and appropriate for the types of motor vehicles or motor vehicle equipment for which it is prescribed, and consider the extent to which the standard will further the statutory purpose of reducing traffic crashes and associated deaths and injuries.

NHTSA's policies in implementing the 1998 Agreement are published in 49 CFR part 553, appendix C, “Statement of Policy: Implementation of the United Nations/Economic Commission for Europe (UNECE) 1998 Agreement on Global Technical Regulations—Agency Policy Goals and Public Participation.” NHTSA's paramount policy goal under the 1998 Agreement is to “[c]ontinuously improve safety and seek high levels of safety, particularly by developing and adopting new global technical regulations reflecting consideration of current and anticipated technology and safety problems.”

Id.

“Motor vehicle safety” is defined in the 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 an accident, and includes nonoperational safety of a motor vehicle.” 49 U.S.C. 30102(a)(9).

B. GTR 9

In developing GTR 9, NHTSA collaborated with experts from contracting parties to the 1998 Agreement,

particularly the European Union (technical sponsor of the GTR

) and Japan. This NPRM begins the process of adopting the GTR as a NHTSA standard through rulemaking.

The 1998 Agreement entered into force in 2000 and is administered by the UN Economic Commission for Europe's World Forum for the Harmonization of Vehicle Regulations (WP.29).

https://www.unece.org/fileadmin/DAM/trans/main/wp29/wp29wgs/wp29gen/wp29glob/globale.pdf.

https://unece.org/fileadmin/DAM/trans/doc/2004/wp29/TRANS-WP29-AC3-07e.pdf.

A number of countries have implemented GTR 9.

Even before GTR 9 was established, Europe and Japan had similar pedestrian protection regulations in place. After GTR 9 was established, WP.29 adopted it as a full UNECE regulation for all nations under the 1958 Agreement (Regulation No. 127—Pedestrian Safety Performance).

In recent years, U.S. variants share similar global designs as vehicles currently sold in the E.U. that attain the levels of head protection described in GTR 9. However, as discussed later, interpretation of certain GTR 9 provisions have varied when implemented into national regulations.

GTR 9 has been amended several times, but the U.S. has not been a signatory to any of the amendments or corrigenda. Thus, in general, this NPRM focuses on the original GTR and not later amendments. The first amendment was related to the applicability of vehicles with short hood areas and increased the number of vehicles excluded from the requirements of GTR 9. We discuss this provision and exclusion in section V.B. of this NPRM. At the same time, a corrigendum was accepted that clarified that the HIC areas may be broken up into pieces and need not be continuous. This is a concept that NHTSA had assumed was part of the GTR; this NPRM explicitly incorporates this concept in the proposed regulatory text (see also section VII.B of this NPRM). Finally, the GTR was amended to replace the leg impactor with a more advanced tool. This amendment relates to provisions that are outside of the scope of this NPRM.

https://unece.org/transport/standards/transport/vehicle-regulations-wp29/global-technical-regulations-gtrs.

The U.S. is not a party to the 1958 Agreement. A contracting party to the 1958 Agreement can choose which regulation(s) it wants to adopt, but the regulations in the 1958 Agreement must be adopted “as is.” They do not contain different stringency levels. Also, the 1958 Agreement provides for reciprocal recognition of type approvals among Contracting Parties. This means that a vehicle type that has been type approved by one Contracting Party must be accepted by other 1958 Agreement Contracting Parties.

GTR 9 has two sets of performance requirements: (a) for the hood top and fenders tested by a headform impact; and (b) for the vehicle front-end area (encompassing the bumper and grille) tested by a legform impact. Vehicle hoods conforming to the GTR's specifications mitigate child and adult pedestrian head injury, and bumpers and grilles conforming to the GTR reduce the risk of adult leg injury. This NPRM proposes to implement the GTR's provisions for the hood top and fenders. The May 6, 2023, NCAP RFC proposed to amend NHTSA's NCAP program to

include Euro NCAP-based provisions for the hood, bumper, and grille. Those head, bumper, and grille Euro NCAP provisions correspond closely to GTR 9.

NHTSA is considering comments to the NCAP RFC in deciding whether and how to proceed with GTR 9's leg protection requirements in an FMVSS.

Test procedures very similar to GTR 9 have been incorporated into many countries' consumer information programs. In addition to Euro NCAP, Japan's J-NCAP program rates vehicles on pedestrian safety, using a headform test, as do the Korean KNCAP and Australasian ANCAP programs.

This rulemaking initiates the process of adopting GTR 9 into the Federal safety standards. This NPRM proposes to implement the head protection requirements of GTR 9 as FMVSS No. 228. The proposed standard modifies some of the GTR's provisions to address the regulatory framework and needs unique to the United States. From years of researching pedestrian head protection using the procedures described in the GTR and applying the procedures to the front-end designs of today, NHTSA has seen instances where the GTR is silent or unclear about its application to some aspects of hood design. Because clarity is needed for the FMVSS, NHTSA has addressed these areas with detailed procedures and criteria in this NPRM that, by design, are consistent with the GTR and with NHTSA's Safety Act provisions. NHTSA has incorporated these clarifications into proposed FMVSS No. 228 so that the standard's procedures are objective and repeatable and meet the need for safety, in accordance with Safety Act requirements. As discussed throughout this document, this NPRM also focuses readers on other ways NHTSA is considering modifying the GTR test procedures for clarity or to push more safety benefits from the U.S. fleet. An example of the latter is NHTSA's consideration of narrowing the border surrounding a test area so that more of the vehicle's hood and fender area would have to meet the HIC requirements.

C. Further Observations About the Differences Between This NPRM and the GTR

In drafting FMVSS No. 228, NHTSA's goal has been to produce a proposal that is true to the agency's understanding of GTR 9 and to the technical best practices provided by the GTR, so as to “fully meet the need in the U.S. for vehicle safety.”

We believe we have achieved this with this NPRM, but at times we have found challenges in relating the original GTR 9 language to the specificity necessary for the self-certification framework of the Safety Act. The Safety Act requires the FMVSS to be practicable, meet the need for motor vehicle safety, and be stated in objective terms. Additionally, the Safety Act requires that NHTSA consider specific factors in prescribing an FMVSS.

Given these requirements and considerations, in some instances we have found the need to define terms and describe test procedures in a more precise way than GTR 9, but in a way that would add to the objectivity and clarity of the safety standard.

supra.

49 U.S.C. 30111(a) and (b).

NHTSA has also shaped this proposal to provide the minimum level of safety required to address the needs we face in this country. NHTSA is aware that other countries have implemented the regulation in some ways that differ from our reading of the regulation in ways that reduce the safety minimum even further. For example, this NPRM adds clarification regarding how the agency will determine the amount of testable hood area that must meet a head injury criterion (HIC) of 1000 or less, compared to a HIC of 1700 or less. This is described more fully in section VI.A of this preamble. UNECE Reg. No. 127 has implemented the GTR 9 in a way that produces a smaller area that must comply with HIC1000 than that which results from the GTR as NHTSA understands it, or as NHTSA proposes in this NPRM to address the growing pedestrian safety needs in this country. In section VIII of this preamble, we provide a detailed discussion of a proposed amendment to GTR 9 that NHTSA has not supported because of its potential to reduce the area subject to headform testing. NHTSA discusses throughout this preamble the differences between this proposed FMVSS No. 228 and the current GTR 9, and the reasons for those differences.

Finally, NHTSA seeks to design FMVSS No. 228 to address pedestrian safety needs particular to the U.S. The regulatory text in this NPRM reflects the wording of the GTR. At the end of various sections, however (see,

e.g.,

section VI.C.1), the preamble describes and requests comment on specific ways NHTSA may change the regulatory text in this rulemaking to better address this country's pedestrian safety needs.

In advance of the publication of this NPRM, NHTSA received a July 7, 2022 letter from the Alliance for Automotive Innovation restating support of the interpretation of the GTR 9 that aligns with the proposed GTR amendment. On December 9, 2022, NHTSA met with the Alliance of Automotive Innovation at their request, to discuss the contents of their letter to NHTSA. The letter can be found in the docket, along with a list of other contacts since April 2022. The agency's position and rationale are fully explained in this preamble, particularly in section VIII.B.

V. Approach of the Proposed Standard

A. Overview

FMVSS No. 228 would prohibit vehicles from exceeding a certain HIC level when subjected to testing simulating a head-to-hood impact. The standard is designed to provide head protection to a walking child and a walking adult when side-struck. This posture was chosen because it represents one of the most common interactions between vehicles and pedestrians. The side-struck posture is also regarded as “worst case.”

Hoods would have to safely absorb and manage the energy of the striking pedestrian's head.

Soni A, Rober T, Beillas P (2013), Effects of Pedestrian Pre‐Crash Reactions on Crash Outcomes during Multi-body Simulations, 2013 IRCOBI Conference, Paper No. IRC-13-92.

The proposed standard defines each hood as having two distinct areas: one where a struck child pedestrian's head would impact (Child Headform Test Area) and one where an adult pedestrian's head would impact (Adult Headform Test Area), both in a 40 km/h (25 mph) vehicle impact. The proposed performance requirements are based on HIC as computed from the acceleration of the headform upon impact. FMVSS No. 228 would limit HIC when tested with the headforms.

The location of a pedestrian's head impact on the hood is dependent on several variables, including the speed of the vehicle impact, the vehicle front-end shape, and the height of the pedestrian. Proposed FMVSS No. 228 is designed so that vehicle countermeasures to meet the HIC limits would benefit pedestrians of all sizes. In section VI of this preamble, we explain in detail the specific areas of the hood that would be regulated under the proposal, as well as considerations for expanding this area.

Proposed FMVSS No. 228 includes detailed procedures that define reference lines on the vehicle from which NHTSA would calculate the area of the vehicle that must provide pedestrian head protection. Proposed FMVSS No. 228's wrap around distance (WAD) procedure is a simple procedure used in several sections of GTR 9 to identify various reference lines on the hood. Reference lines that run laterally across the hood are drawn relative to a specified WAD. Those lines are referred to herein as WAD lines. NHTSA helped develop the WAD procedure for

pedestrian protection test programs internationally.

The WAD is the distance from a point on the ground directly below the bumper's most forward edge, at a specific lateral location, to a designated point on the hood, as measured with a flexible measuring device, such as a non-stretch flexible wire. During measurement of the WAD, the device (the non-stretch flexible wire) is held taut, to measure distances while being held in a vertical longitudinal (x-z) vehicle plane. A WAD of a specified distance can identify a point on the vehicle's hood. A WAD line can be drawn on a vehicle by connecting the end points of the wire as it traverses across the front of the vehicle. We can create a WAD line using wires of different lengths,

e.g.,

a wire of 1000 ± 1 mm can be used to draw a line at 1,000 mm from the ground reference plane (such line is referred to as “WAD1000” in this NPRM), 1700 ± 1 mm (“WAD1700”) and 2100 ± 1 mm (“WAD2100”).

See figure V.1, below, illustrating how WAD is measured.

The naming convention is to follow “WAD” with the length of the wire used for the measurement, and to refer to WAD [wire length] to refer to the line drawn by using the wire and the WAD procedure.

A WAD line can be objectively determined and is a good indicator of where head impacts are likely to occur on any particular hood.

The WAD measurement accounts for both pedestrian height and vehicle front-end configuration. That is, in a 40 km/h crash, a given pedestrian's head-to-hood contact point is approximated by the WAD that corresponds to the pedestrian's standing height.

Paragraph 71 of the “Safety Need” section of GTR 9.

https://unece.org/fileadmin/DAM/trans/main/wp29/wp29wgs/wp29gen/wp29registry/ECE-TRANS-180a9e.pdf.

EP19SE24.003

Key Elements of the Proposal

The proposed standard has certain key elements to replicate the real-world 40 km/h (25 mph) impact in an objective and enforceable manner. The key elements are:

• Relevance to the vehicles involved in pedestrian crashes at 40 km/h (25 mph);

• A methodology incorporating component testing of the hood using headforms representing child and adult pedestrians;

• Performance requirements based on HIC as measured by the headforms;

• A hood mark-off procedure to denote test areas; and

• Flexibility in performance requirements to address practicality challenges.

These key elements and others are discussed in detail below.

B. Relevance to the Involved Vehicles

FMVSS No. 228 would apply to passenger cars, and to MPVs, trucks, and buses with a GVWR of 4,536 kg (10,000 lb) or less, except for vehicles with short front ends (a very short front hood area). Proposed FMVSS No. 228 would also apply to bidirectional vehicles,

i.e.,

vehicles that can be operated in either direction. We discuss these issues below.

Vehicles With Short Front Ends

Reflecting the text of GTR 9, the NPRM's proposed regulatory text (S3) excludes MPVs, trucks, and buses where the distance, measured longitudinally on a horizontal plane, between the transverse centerline of the front axle and the seating reference point (SgRP) of the driver's seat, is less than 1,000 mm.

In the statement of technical rationale for GTR 9, the drafters argued that these vehicles have a very short hood and a front shape that is very close to vertical, so the pedestrian kinematics with these vehicles are believed to be very different than a collision with a vehicle with a longer hood. The drafters also concluded that there are difficulties in applying the tests to these vehicles, particularly regarding the determination of test zone reference lines.

This is dimension L114 in SAE J1100 “Motor Vehicle Dimension.” A later amendment to GTR published in 2011, which was not signed by the U.S., extended this dimension to 1,100 mm. (ECE/TRANS/180/Add.9/Amend.1/appendix 1).

NHTSA drafted the regulatory text with this exclusion, but NHTSA requests comments on whether the subject vehicles should be included in FMVSS No. 228. Notwithstanding the drafters' reasons for excluding the vehicles from GTR 9, NHTSA believes applying proposed FMVSS No. 228 to these vehicles may be appropriate given developments since the GTR. With the advent of new designs in electric vehicles, including designs of automated vehicles on the road today with very short front ends, front end designs appear to be evolving to less

conventional hood designs. The agency is aware of prototype ride-share automated vehicle platforms, such as the Cruise Origin and Zoox, and of electric vehicles (EVs) being marketed by Canoo, that have a very short front hood area or a flat front face.

We are concerned that future automated and/or electric vehicles may become more prevalent in the fleet and that they could be excluded from the standard simply because of this GTR provision.

NHTSA understands that the Cruise Origin and Zoox vehicles do not have a traditional driver's seating position.

In addition, we base our concerns about this exclusion on present day vehicles and their presence in the U.S. vehicle fleet. The agency took an available selection of vehicles and measured the horizontal distance from the front axle to the seat bight (the area close to and including the intersection of the surfaces of the vehicle seat cushion and the seat back), with the seat adjusted to the full forward and full rearward position. The vehicles and resulting dimensions are provided in table V.1, below. The position of the SgRP for these vehicles was not readily available, but the distance between the axle and the SgRP would likely lie somewhere between the range of distances measured to the seat bight. As stated above, the GTR 9 exclusion would be triggered if the distance from the front axle to the SgRP is less than 1,000 mm.

The agency found that at least one type of full-size cargo van (Ford Transit) could possibly qualify for the exclusion. Looking at both small and full-size cargo and passenger vans, it is clear that many of them share similar design attributes of a short hood and a relatively forward seating position with respect to the front wheels.

This suggests to the agency that the most likely types of vehicles in the current fleet that would be excluded are small and large vans. For 2021, this van segment had a sales volume of approximately 400,000 vehicles, constituting about 2.7% of the 15 million total 2021 sales.

65 66

Thus, the 2.7% value provides an upper bound on the number of vehicles likely to meet the exclusion criteria. It also seems clear to the agency that relatively minor changes in design could place a vehicle in the excluded category. We are concerned about the effects of the exclusion in reducing the benefits of this proposal.

Some vehicles in this category would be the Chevrolet Express, Ford E-Series, Ford Transit, Ford Transit Connect, GMC Savana, Mercedes-Benz Metris, Mercedes-Benz Sprinter, Nissan NV, Nissan NV200, Ram ProMaster, Ram ProMaster City.

https://www.goodcarbadcar.net/2021-us-commercial-van-sales-figures-by-model/.

https://www.goodcarbadcar.net/2021-us-vehicle-sales-figures-by-model/.

NHTSA has tested a vehicle with a short front end similar to vehicles in the excluded category and has successfully conducted headform testing. This testing demonstrated that the proposed WAD-based test procedure can be applied to short front end vehicles. NHTSA also believes it would be practicable for the vehicles to meet the proposed standard. NHTSA tested the 2004 GMC Savana van to a slightly modified version of the GTR 9 test protocol, with a 32 km/h head impact speed. Three of four hood impacts had a HIC below 600. The fourth test, near the edge of the hood had a HIC of less than 1000.

These results suggest that FMVSS No. 228 would be practicable for similar vehicles.

Stammen J, et al, “Pedestrian Head Safety Survey of U.S. Vehicles In Support of the Proposed Global Technical Regulation (GTR)” (2006).

https://unece.org/DAM/trans/doc/2008/wp29/WP29-144-03e.pdf.

Table V.1—Sample of Vehicle's Horizontal Distance From the Front Axle to Seat Bight

Year

Make/model

Approximate distance to seat bight

(mm)

Full forward

Full rearward

2015

Ford Transit

930

1180

2016

Honda Fit

1200

1480

2003

Honda Pilot LX

1250

1500

2016

Nissan Rogue

1270

1480

2011

Chevrolet Cruze

1300

1550

2012

Ford Focus

1320

1570

2001

Honda Civic

1330

1530

2012

Ford Fusion

1380

1760

2006

Infinity M35

1400

1650

2002

Jeep Wrangler

1680

1880

We request comments on the practicability concerns related to these vehicles, specific challenges such vehicles present related to the proposed test procedure, and what adjustments, if any, would be available to apply proposed FMVSS No. 228 to such vehicles. We also request comments on the safety need and outcomes of including all light vehicles under the proposed standard to maximize potential safety benefits to pedestrians and other vulnerable road users.

Rear Engine Vehicles and Bidirectional Vehicles

It is the agency's intent to apply FMVSS No. 228 to rear engine vehicles, as long as they meet the other applicability requirements. This is because the location of the tested area is not dependent on where the engine is located, but rather is keyed to the front of the vehicle. We believe GTR 9 is intended to apply to such vehicles.

A similar assumption cannot be made about whether GTR 9 is intended to cover bidirectional vehicles. Certainly, there is no explicit mention of these vehicles. Nonetheless, it is NHTSA's intent to apply FMVSS No. 228 to bidirectional vehicles. NHTSA believes that such vehicles may become more common, particularly with the advent of more automated vehicle platforms, and that there is a safety need to apply proposed FMVSS No. 228 to the vehicles because they could strike pedestrians. Therefore, we have explicitly made the definitions and regulatory text of proposed FMVSS No. 228 neutral concerning the direction of vehicle operation,

i.e.,

the regulatory text is intended to work for bidirectional vehicles. First, we have explicitly included bidirectional vehicles in the

Applicability section of the proposed regulatory text. Next, we have defined “bidirectional” vehicle to mean a vehicle that is intended to operate at similar speeds and with similar maneuverability in both directions of the vehicle longitudinal axis.

Similarly, we have defined “front” to mean the leading portion of the vehicle during full speed operation. We seek comment on whether the terms accomplish the agency's objective of including bidirectional vehicles in FMVSS No. 228.

The terms of this definition are intended to distinguish these vehicles from conventional vehicle that can also operate in two directions. However, for conventional vehicles the rearward or backing direction is not intended for full speed operation, but rather low speed and typically in a single gear.

C. Advantages of Headform Component Tests

The NPRM proposes using headform component tests rather than full vehicle dynamic tests in which a vehicle would strike a pedestrian dummy. The agency believes that headform component tests have advantages over full vehicle dynamic tests. The area of the vehicle hood that could contact a pedestrian's head is large. A set of headform component tests enables NHTSA to target hood areas that the agency believes represent danger points, and test with a high degree of accuracy and repeatability. Like all crashes, every real-world pedestrian crash is unique in some way. When the range of statures and other crash variables are taken into account, the area of the vehicle that could contact the head is so large that currently the only feasible test method is one that is based on a sub-system test approach. Proposed FMVSS No. 228 uses such an approach by focusing on the hood and by making use of a set of headform component tests that can target the hood area efficiently. The headform mass, impact angle, and impact speed can all be controlled in a way that will assure that the standard will provide safety in real world impacts and can be enforced. The characteristics of the headforms are discussed in detail later in this preamble.

Pedestrian test dummies have been developed for crashworthiness research. In general, the repeatability of tests using a pedestrian dummy is relatively poor because small variations in initial positioning influence the head-to-hood contact as the dummy passes through its sequence of movements after being struck by the vehicle. Moreover, head impact locations are highly dependent on stature and gait, so use of a single pedestrian dummy for crashworthiness purposes would make it very difficult to assess hood areas that are likely to be struck by persons not represented by the dummy.

D. Head Injury Criterion (HIC)

Consistent with GTR 9, NHTSA has determined that HIC is an appropriate injury criterion for the proposed standard. The proposed standard would require HIC to be less than 1000 for most hood impacts. HIC is calculated using the expression below, where the resultant acceleration, a

, at the headform center of gravity and specified as a multiple of g (the acceleration of gravity), is integrated over 15 millisecond ranges covering the entire impact.

EP19SE24.004

HIC, which is a function of the tri-axial linear acceleration in the headform, is well established and used in numerous occupant protection FMVSS. A HIC value of 1000 represents an 11 percent risk of a brain injury of severity level AIS 4 or greater and a HIC value of 1700 represents a 36 percent risk.

Many of NHTSA's impact protection standards use HIC to measure the potential for head injury and limit HIC to a value of 1000; these include FMVSS No. 201,

Occupant protection in interior impact,

FMVSS No. 214,

Side impact protection,

and FMVSS No. 222,

School bus passenger seating and crash protection.

NHTSA considered other brain injury metrics, such as angular velocity, but determined that HIC is the best available criterion at this time.

AIS (Abbreviated Injury Scale) ranks individual injuries by body region on a scale of 1 to 6: 1=minor, 2=moderate, 3=serious, 4=severe, 5=critical, and 6=maximum (untreatable).

In an actual vehicle-pedestrian collision, head rotation that occurs before, during, or after the head impact with the hood could result in concussive brain injuries. However, the biofidelity of a headform—unattached to the body—could be compromised in its ability to generate angular velocity representative of an actual pedestrian head impact. The agency would like to understand more about the biofidelity of a headform when used to measure angular velocity.

Proposed FMVSS No. 228 would require vehicles to meet HIC limits when subjected to hood headform impactor testing. It defines the forward, rear and side areas of the hood, thus defining a primary area—the “Hood Top.”

From there, a typically smaller “Hood Area” is defined using, among other things, the Wrap Around Distance lines described earlier. Of this Hood Area, the standard would define a Child Headform Test Area and an Adult Headform Test Area, excluding margins at the side and potentially at the front and rear, which would be tested with the child and adult headforms, respectively. The HIC must not exceed 1000 (HIC1000) over a certain portion of the Child and Adult Headform Test Areas, as a percentage of the overall Hood Area. Specifically, the portion of the Child Headform Test Area that must meet the HIC1000 provision must be at least one-half of the numerical value of the Hood Area with a Wrap Around Distance of less than 1,700 mm (WAD1700).

Secondly, the portion of the Combined Child and Adult Headform Test Areas that must not exceed the HIC1000 provision must be at least two-thirds of the numerical value of the Hood Area. For practicability reasons to accommodate a manufacturing need to reinforce and stiffen the hood edges, the remaining test area is permitted to have HIC higher than 1000, but nonetheless limited to 1700 for both headforms.

The procedures for defining these areas are discussed below in this preamble.

The drafters of the GTR determined that because the location of necessary under-hood components cannot be fundamentally changed, it is unavoidable that they are located in the child headform test area. Thus, the GTR provides that the relaxation zone for the child headform test area may be half of the zone (as opposed to

1/3

of the zone, as in the adult test area).

Such reasons include the need to minimize any fluttering of the hood at high speeds and the ability to slam the hood shut without deforming the seams at the junction of the hood and fender.

HIC time window, 15 ms.

Proposed FMVSS No. 228 would reference a 15 millisecond (ms) time window when applying the HIC criterion. For any 15 ms time window, HIC must be below the HIC criterion (

e.g.,

HIC1000). A 15 ms time window is used in proposed FMVSS No. 208 verses a longer window

(

e.g.,

using a 36 ms timeframe) because the FMVSS No. 228 impact is hard and of short duration. Longer duration impacts may have a greater HIC when using a 36 ms window (a longer duration impact can occur in air bag tests when the test dummy's head maintains contact with the air bag through a crash event). For hard, short duration impacts such as the headform testing used in proposed FMVSS No. 228, HIC derived from a 15 ms timeframe produces the same numerical value as HIC derived from a longer window (36 ms). Since the FMVSS No. 228 impact is hard and of short duration, a 15 ms window is appropriate.

Further, GTR 9 uses a 15 ms window instead of 36 ms to improve the objectivity of the test. The 15 ms window was viewed as a common-sense safeguard against signal corruption due to a secondary impact. With hood impacts, there is a risk that the headform may undergo a secondary impact in rapid succession (in less than 36 ms), as the head could strike the hood target then bounce away and land on a structure such as the windshield, which is outside of the test area. To safeguard against the effects of a secondary impact, the 15 ms criterion was implemented as a convenient means to help assure that the HIC value reflects only that portion of the headform acceleration caused by a hood impact within the test area. The procedures developed by IHRA, ISO, and the EEVC all use a 15 ms window to calculate HIC. This criterion and threshold have been carried over to all subsequent international standards.

Request for Comment on HIC

• We generally agree with the approach and have proposed it in this NPRM. However, we would like to know more about the following issues. We have not seen a need to use a 15 ms window, as opposed to a 36 ms window, because head impacts to external car structures are very short, occurring within a few milliseconds of contact. In practice, 15 ms and 36 ms windows generally have produced the same value in pedestrian protection tests. Further, in our own testing, we have not observed an instance where the use of a 36 ms window would have led to signal corruption due to a secondary impact. We request comment on the need for a 15 ms timeframe related to testing issues.

• We also seek comment on whether a 15 versus 36 ms window could affect HIC measurements when testing active hoods or cowl air bags,

features that have appeared in recent years, particularly in non-U.S. vehicles. We request comments on whether HIC computed in a 36 ms timeframe would be more appropriate and protective against head injury for vehicles with active hoods or air bag technologies than HIC computed in a 15 ms window. Should FMVSS No. 228 adopt a HIC 36 ms timeframe to account for these technologies?

The cowl is the lower edge of the windshield opening. Active hoods move when a pedestrian impact is sensed, increasing the distance between the hood and the hard engine components below. A cowl air bag covers the cowl during a pedestrian impact.

E. Speed and Angle at Which the Headforms Would Impact the Hood

The headforms would impact the vehicle hood at specific speeds and impact angles replicating a real-world 40 km/h (25 mph) impact.

1. Headform Impact Speed

Proposed FMVSS No. 228 would require the launch direction to be entirely within the plane parallel to the vehicle x-z plane (vertical longitudinal plane) and the impact speed for both headforms would be 35 km/h (22 mph).

This speed is based on observations of postmortem human subjects (PMHS) and pedestrian surrogate testing, computer modeling, and reconstructions of real-world pedestrian collisions. The proposed velocity of 35 km/h (22 mph) replicates the actual head-to-hood impact speed of a pedestrian struck by a vehicle traveling at 40 km/h (25 mph).

The vehicle coordinate system used in this NPRM is consistent with SAE J1100 “Motor Vehicle Dimension.” The coordinate system is as follows: +x direction is the longitudinal vehicle axis (rearward direction of travel); +y direction is the lateral vehicle axis (pointing away from the right side of the vehicle); +z direction is pointing vertically upward.

Researchers have historically used the ratio of head impact speed to vehicle speed to characterize the head-to-hood interaction. A head impact speed of 35 km/h (22 mph) in a 40 km/h (25 mph) collision yields a ratio of 0.875. Depending on conditions, such as the shape of the vehicle front-end, the height of the leading edge of the hood, and the height of the pedestrian, the ratio for an adult may be as high as 1.4 or as low as 0.7.

The proposed test speed encompasses the majority of pedestrian collisions. About 70 percent of injurious pedestrian collisions occur at vehicle speeds of 40 km/h (25 mph) or less (see figure V.2, which averages data from 2011 to 2020).

In addition, the 35 km/h (22 mph) test speed is a critical part of the real-world event replicated by the headform impact test. The dynamics of a pedestrian-vehicle interaction change at a target speed substantially greater than 40 km/h (25 mph). Above 40 km/h (25 mph), an initial hood-to-torso interaction takes place where the pedestrian tends to slide along the hood, with the head overshooting the hood. The head-to-hood interaction that the proposed test procedure replicates would lose its real-world relevance if a substantially higher test speed were used.

Mizuno Y, Ishikawa H (2001), Summary of IHRA pedestrian safety WG activities—proposed test methods to evaluate pedestrian protection afforded by passenger cars, Paper No. 280, The 17th International Technical Conference on the Enhanced Safety of Vehicles, Amsterdam, The Netherlands, June 4-7, 2001.

The proposed test speed addresses a safety need within the bounds of practicability. Although pedestrian fatalities, on average (50% cumulative value in figure V.2), occur at a collision speed of 70 km/h (44 mph), the practicability of designing a hood to conform to HIC1000, based on energy dissipation, appears to become less feasible at a headform impact speed of 61 km/h (38 mph) (assuming the same ratio of head speed to vehicle speed used from the proposal, the 61 km/h would have about 3 times the energy). Moreover, the proposed rule would reduce the severity of many head injuries that occur at speeds covered by the test.

BILLING CODE 4910-59-P

EP19SE24.005

BILLING CODE 4910-59-C

Notwithstanding the proposed headform test speed of 35 km/h (22 mph), NHTSA believes there would be benefits from the proposed standard for some crashes above a 40 km/h (25 mph) vehicle speed, as the countermeasures used to meet the proposed HIC thresholds could mitigate some of the harm resulting from head-to-hood strikes that can occur in the higher speed crashes. Also, vehicle designs that provide head protection in a 35 km/h (22 mph) headform impact may also have the effect of reducing the severity of injuries to body regions other than the head in collisions at vehicle speeds above 40 km/h (25 mph). For example, at vehicle to pedestrian collision speeds of 50 km/h (31 mph) and higher, bi-lateral rib fractures have been observed in thorax-to-hood contacts.

We request comment on whether some of these types of injuries could be mitigated by hood designs meeting FMVSS No. 228.

Watanabe A et al (2011), Research of collision speed dependency of pedestrian head and chest injuries using human FE model (THUMS version 4), 22nd International Technical Conference on the Enhanced Safety of Vehicles (ESV), Paper No. 11-0043, Washington DC, June 2011.

NHTSA anticipates PAEB would mitigate 238 fatalities and 2,672 injuries of the current target population for this NPRM and has based our benefits estimate for this NPRM on that assumption. Automatic emergency braking helps prevent crashes or reduce their severity by applying a vehicle's brakes automatically. The systems use on-board sensors to detect an imminent crash, warn the driver, and apply the brakes if the driver does not take action quickly enough or increase the braking application in the case that the driver does not sufficiently brake to avoid contact. When new vehicles are equipped with PAEB that meets the requirements specified in FMVSS No. 127, fewer pedestrians will be struck, which would have the effect of reducing the target population for this rulemaking. On the other hand, for many impacts that occur at speeds too high for PAEB to completely mitigate, PAEB will lower the vehicle's speed so that impact speeds that would have been greater than 40 km/h (25 mph) could be reduced to close to or below 40 km/h (25 mph). This would theoretically add to the target population of this rulemaking because these are pedestrian crashes that this proposed pedestrian head protection standard could potentially address. And, as proposed FMVSS No. 228 would ensure the striking vehicles have protective features that protect against serious to fatal head injury in these impacts, those pedestrians that would be newly included in the target population of this NPRM due to PAEB could arguably be included among those saved from serious to fatal injury by this head protection rulemaking. However, we have not accounted for the extent to which the FMVSS No. 127 would add to the target population or to the population of persons benefiting from this head protection NPRM because of unknowns about how those benefits could be quantified. As a result, our analysis likely underestimates benefits. With this in mind, in the PRIA we estimate that PAEB would decrease the fatality target population addressed by FMVSS No. 228 by about 4 percent. Comments are requested on this issue.

• NHTSA requests comments on increasing the test velocity above 35 km/h (22 mph) to capture a greater percentage of pedestrian impacts presented in the field data and achieve additional safety benefits.

2. Headform Impact Angle

Consistent with the GTR, NHTSA proposes that, at impact, the velocity vector of the child headform would form a 50-degree angle down from the horizontal (50° ± 2° at the time of impact). For the adult headform, the

angle would be 65 degrees (65° ± 2° at the time of impact). (See figure V.3, showing the child headform impact and figure V.4, showing the adult headform impact).

BILLING CODE 4910-59-P

EP19SE24.006

BILLING CODE 4910-59-C

The head impact angles were developed based on observations of PMHS and pedestrian dummy tests, computer modeling, and reconstructions of real-world pedestrian collisions. The impact angle in a real-world impact is greater for taller pedestrians than for shorter pedestrians, and this is reflected in the test procedure. The impact angle in real-world impacts also varies depending on the shape of the vehicle front-end, particularly the height of the leading edge of the hood. Passenger cars (with low leading edges) generally produce head-hood angles that are closer to 90 degrees than SUVs.

The proposed 65-degree impact angle for the adult headform test is the same as the IHRA specification. The bulk of research data showed head impact angles in the range of 50 to 80 degrees; IHRA selected a nominal headform

angle of 65 degrees.

Component tests conducted by NHTSA

showed that HIC sensitivity to impact angle varied with hood stiffness and proximity to hard understructures. Where there were no hard understructures, HIC values exhibited very little sensitivity to impact angle. In general, HIC variation of less than 10 percent was shown between 50 and 80 degrees.

Because the typical hood is angled forward at about 15 degrees, it causes the 65 degree adult headform impact to create an 80 degree angle of incidence with the hood,

i.e.,

a slightly angled (non-normal) headform impact.

Stammen JA, Saul RA, Ko B (2001), Pedestrian head impact testing and PCDS reconstructions, Paper No. 326, 16th International Technical Conference on the Enhanced Safety of Vehicles (ESV) Proceedings, Amsterdam, The Netherlands, June 4-7, 2001.

The selection of a 50-degree impact angle for the child headform test was partly based on computational simulations using a 5th percentile adult female (which is about the same size as an average 12-year-old child)

and a 6-year-old child. The simulation results for the 5th percentile female gave similar average values to those found for the 50th percentile adult male. For the 6-year-old, however, simulations showed that the head impact angle was more sensitive to car shape, particularly to the height of the hood leading edge. An average value of 45 degrees was found for the 6-year-old. The 50-degree impact angle is representative of the simulation results with a bias towards the 6-year-old child.

Janssen and Nieboer, Sub-system tests for assessing pedestrian protection based on computer simulations, Proceedings of the IRCOBI Conference, Berlin, September 1991.

Request for Comment on the Proposed Impact Angle

• We believe that the headform impact test would be the most stringent when the impact is normal to the hood surface (a 90-degree angle of incidence to the surface).

If the impact is normal (90 degrees) and there is no glance-off, all of the headform's energy would have to be absorbed by the hood to stop its downward movement. However, a 90-degree angle of incidence to the surface may not be consistent with real world impacts at speeds up to 40 km/h (25 mph) and would require the impactor launch angle to vary by test location. We request comment on whether the standard should increase the impact angles to increase stringency notwithstanding a possible reduction in the representativeness of real-world crashes.

Assuming that a 15 degree hood angle is typical, a 90 degree head-hood angle would correspond to a 75 degree headform impact angle from the horizontal.

VI. Defining the Relevant Areas Subject to the Standard

Overview:

Proposed FMVSS No. 228 would have detailed procedures that define reference lines on the vehicle from which NHTSA would calculate the area of the vehicle that must provide pedestrian head protection. The proposed procedures (including the WAD procedure) are needed to enable the agency to objectively define the areas on the vehicle that are subject to the standard, the total HIC1000 area that must be provided, and the locations of the Child and Adult Headform Test Areas. The procedures are necessary for NHTSA to assess a test vehicle's compliance with the standard. NHTSA would use the procedures to define these relevant areas and would not use manufacturer input to define them.

As relevant areas are defined in the following section of this NPRM, any necessary clarification to GTR 9 will be identified and described. Although the various hood reference lines should be essentially identical to those in GTR 9, the terminology used to describe the areas and reference lines are not identical. A more complete comparison of the terminology used in GTR versus this NPRM can be found in section VIII.

The areas subject to the standard are the areas likely to be impacted by the head of a pedestrian and for which countermeasures are or could reasonably be available. The most severe head injuries can be due to contact anywhere on the hood surface.

Consistent with GTR 9, the first step in establishing these areas would be to identify the “Hood Top.”

The Hood Top forms the basis upon which all other areas are determined. We discuss the method for determining the Hood Top in section VI.A below. The next step would be to establish the “Hood Area” using the procedures discussed in section VI.B below.

The final step in the process would be to determine the test areas,

i.e.,

the Child and Adult Headform Test Areas. As part of this process, consistent with GTR 9's 82.5 mm margins, the standard would identify “HIC Unlimited Areas”

and exclude them from meeting HIC limits. While the agency is unaware of data that indicates there is a lower likelihood of pedestrian head contact in this area compared to other areas of the hood, the GTR and proposed standard provide for HIC Unlimited Areas as a practicability measure to accommodate a manufacturing need to reinforce and stiffen the hood edges.

The HIC Unlimited Area bounds the Child and Adult Headform Test Areas at the hood edge.

Koetje B and Grabowski J. A Methodology for the Geometric Standardization of Vehicle Hoods to Compare Real-World Pedestrian Crash; Annuals of Advances in Automotive Medicine. 2008; 52: 193-198.

The Hood Top is identical to the “Bonnet Top” of GTR 9.

As we will describe below, in some instances the Hood Area may be equivalent to the Hood Top.

NHTSA would use the procedures in the standard to identify the HIC Unlimited areas and would not use manufacturer data to define them. We note that GTR 9 does not use the “HIC Unlimited” terminology, but makes the same reduction to the testable area.

As noted earlier, such reasons include the need to minimize any fluttering of the hood at high speeds and the ability to slam the hood shut without deforming the seams at the junction of the hood and fender.

Portions of the Child and Adult Headform Test Areas are either subject to HIC1000 or HIC1700 limits. The requisite HIC1000 area that is calculated based on the total Hood Area must be located within the Child and Adult Headform Test Areas and are not part of the HIC Unlimited Area. Proposed FMVSS No. 228 would provide manufacturers considerable leeway in determining where to place the HIC1700 area to afford them as much flexibility as reasonably possible in configuring the structures comprising their under-hood designs. The vehicle manufacturer would inform NHTSA of the locations of the HIC1700 areas. NHTSA would use that information to confirm that sufficient HIC1000 area has been provided, delineate the HIC1700 areas, and confirm through headform test results that the appropriate HIC limits are met.

A. Determining the Hood Top

The Hood Top is enclosed by the intersection of the following borders (these borders are depicted in figure VI.1 below):

•

Front border:

Leading Edge Reference Line.

•

Side border:

Side Reference Lines.

•

Rear border:

Rear Reference Line.

BILLING CODE 4910-59-P

EP19SE24.007

1. Front Border of the Hood Top

The front border of the Hood Top would consist of the vehicle's “Leading Edge Reference Line” (LERL). The LERL is determined for most vehicles by running a 1,000 mm straight edge angled at 40° (down from the horizontal) along the front edge of the vehicle. The lower end of the straight edge is specified to be 600 mm off the ground. The specified height of 600 mm was chosen to avoid the bumper when marking off the hood leading edge. (See figure VI.2 below, illustrating the procedure.) The length and angle of the straight edge result in the upper end being placed at 1,243 mm from ground level. The use of a 40° angle provides an objective means to delineate the grille/bumper from the hood. Moving along the width of the front-end and while holding the straight edge parallel to the vehicle x-z plane, the contact points between the straight edge and the vehicle define the line. The reference to a 1,000 mm long straight edge is in the GTR. Our understanding is the 1,000 mm length of the straight edge was chosen for convenience, and may be a result of previous pedestrian test protocols.

We will discuss later below how, for a subset of vehicles, the straight edge length affects the front hood border.

EP19SE24.008

2. Side Borders of the Hood Top

The side borders of the Hood Top would be determined by identifying the Side Reference Lines (SRLs). An SRL would be drawn by running a straight edge angled at 45° along the side of the vehicle. Unlike in the procedure establishing the LERL, the straight edge is not held a fixed distance from the ground when determining the SRL. The 45° angle provides an objective means to delineate the fender from the hood. Moving along the length of the vehicle, the contact points between the straight edge and the vehicle define the SRL. The side border has been defined this way in all previous test protocols preceding the GTR, including those of the EEVC, IHRA, ISO, and NHTSA's earlier work on a pedestrian protection standard. It is also used in Euro NCAP. (See figure VI.3, provided for illustration purposes.)

EP19SE24.009

3. Rear Border of the Hood Top

The rear border of the Hood Top would be determined by identifying the Rear Reference Line (RRL). The RRL would be determined by inserting a 165 mm sphere into the cowl

and against the windshield such that the sphere is in contact with the windshield and a point on the surface of the hood (usually its rear edge). The RRL is formed by moving the sphere along the width of the windshield while always keeping the sphere in contact with the windshield and the hood. The contact points between the sphere and the hood define the RRL. (See figure VI.4, provided for illustration purposes.)

The cowl is the lower edge of the windshield opening. The wiper blades, linkages, and arms are removed during this process defining the RRL.

EP19SE24.010

BILLING CODE 4910-59-C

4. Provisions for Front Corners

The GTR is at times ambiguous regarding where to pinpoint the intersection of the Leading Edge Reference Line (LERL) and the Side Reference Line (SRL) defining the Hood Top. The front border of the Hood Top is defined by the LERL. On vehicles that were on the road fifteen or more years ago, the hood front border did not have a high degree of curvature, and the point of intersection with the side border was easy to discern. However, on newer models, the LERL is usually curved and often not smooth—such that it may be possible for the side border to intersect in more than one place (although we expect such occurrences to be rare). This is depicted in the figure below (figure VI.5).

EP19SE24.011

To identify the boundaries for the Hood Top, it is important for NHTSA to know where the LERL intersects the SRL. In European test protocols used today (

e.g.,

Euro NCAP V7.0 and later versions, UNECE Reg. No. 127), a “Corner Reference Point” for the Hood Top is defined to clarify this situation (shown graphically in figure VI.5). In those test protocols, the Corner Reference Point is the intersection of the LERL and the SRL. Additionally, Euro NCAP clarifies that if there are multiple intersections, the most outboard intersection comprises the Corner Reference Point.

We have included a definition of “Corner Reference Point” in our proposal for the same purpose, which would make clear that the Corner Reference Point of the Hood Top is the most outboard intersection when the LERL and the SRL intersect at multiple points.

GTR 9 does not define a Corner Reference Point and makes no provision of multiple intersections between the LERL and SRL.

As we discuss below, there are other areas defined on the vehicle hood that may also have multiple intersections at the front corners. To be clear in the proposed standard as to how the areas are determined, we are also similarly defining the “Corner Reference Point of the Child Headform Test Area” and the “Corner Reference Point of the Hood Area.”

Finally, as mentioned previously, there is a proposed provision for determining the LERL of a high front vehicle when the tip of the straight edge makes first contact with the vehicle as opposed to elsewhere on the straight edge (see figure VI.16 later in the document). In such an instance, consistent with GTR 9, the WAD1000 line becomes the LERL. However, when this procedure is followed, it is likely that the WAD1000 line and SRL would not intersect due to their height difference, and thus, using procedures that would apply to vehicles of lower front ends, the Corner Reference Point of the Hood Top cannot be determined. To correct this deficiency, proposed FMVSS No. 228 would provide a procedure to connect the SRL to the WAD1000 line and thus establish the Corner Reference Point of the Hood Top. This procedure involves establishing the Corner Reference Point of the Hood Top as if the LERL were determined by contact with the straight edge. The SRL and the WAD1000 line are then connected by a line spanning the distance from the Corner Reference Point of the Hood Top and the WAD1000 line.

5. Provisions for Rear Corners

When the sphere and cowl procedure is conducted, often the RRL does not intersect the SRL,

i.e.,

the edges of the lines do not meet at the corners. Because it is important to defining the test area that the hood borderline be continuous, proposed FMVSS No. 228 provides an objective way to connect these two lines using a procedure in GTR 9.

FMVSS No. 228 would specify that the RRL is extended using a semi-circular template of radius 100 ± 1 mm, marked with four reference marks “A” through “D,” as shown in figure VI.6.

GTR 9, section 3.6, p. 38.

EP19SE24.012

The template would be placed on the vehicle with corners “A” and “B” coincident with the side reference line. With these two corners remaining coincident with the side reference line, the template would be slid gradually rearwards until the outer edge of the template makes first contact with the RRL. If the first point of contact between the template and RRL lies outside the arc identified by points “C” and “D,” the RRL is extended and/or modified to follow the circumferential arc of the template to meet the SRL, as shown in figure VI.7 (provided for illustration purposes).

EP19SE24.013

If the outer edge of the template shown in figure VI.6 cannot contact the rear reference line while simultaneously contacting the side reference line at points “A” and “B,” or the point at which the rear reference line and template make first contact lies within the arc identified by points “C” and “D,” then the standard prescribes that larger templates must be used where the radii are increased progressively in increments of 20 mm, until all the criteria above are met.

6. Clarifying the Borders

Through years of researching pedestrian head protection using the procedures described in the GTR, NHTSA has seen instances where the GTR is silent or ambiguous about its application to some aspects of hood design. NHTSA has developed ways to address these challenges consistent with the GTR and NHTSA's Safety Act requirements such that the FMVSS set forth objective and repeatable criteria. We propose to incorporate these lessons learned into FMVSS No. 228's test procedures and criteria, some of which are highlighted below.

a. Addressing Discontinuities and Abrupt Direction Changes When Scribing the Side Reference Lines

In marking off the SRL using the straight edge, a contour on the hood or fender could create a continuous line with sudden changes in direction, or zigzagging in what was previously a relatively smooth line. NHTSA considers this marked-off side border a valid SRL and would not smooth out the line in a compliance test as may be customary in the European approval process.

Pedestrian Protection—ACEA Interpretations to the Respective Legislation of the UNECE and the European Union, revised November 30, 2010, Brussels. This document provides supplemental definitions to several test procedures of GTR 9 that ACEA considered to be ambiguous. ACEA is the European Automobile Manufacturers Association, a group representing European-based automobile manufacturers.

https://www.acea.auto/acea-members/

Yet, some vehicle contours may result in a discontinuous line (a line with a break in it). In other words, a “jump” could occur such that the border is no longer continuous because the points contacted by the straight edge alternated between portions of the vehicle surface separated by some distance. See figure VI.8 below, which depicts a hypothetical vehicle with a discontinuous SRL (discontinuity is not to scale). As shown in the figure, in this situation, NHTSA would “fill in” the gap and make the broken line whole again using a procedure that involves holding a non-stretch wire taut across the gap in the line. The break is filled by scribing a line created by the projection of the wire vertically downward on the vehicle surface. This procedure also results in a zigzagging final line, which is an acceptable outcome.

EP19SE24.014

b. Multiple Contact Points

NHTSA has also encountered situations using the straight edge where the vehicle may be contoured such that the straight edge contacts two points at once (see figure VI.9). Such a situation could occur when scribing any of the hood borders. To address this, where multiple or continuous contacts occur NHTSA would use the contact that provides the largest Hood Top (

i.e.,

the most outboard contact point for the side boundary, forward-most for the front boundary, and rearward-most for the rear boundary). This convention is also specified in Euro NCAP and the NCAP RFC for side borders. (We note that, as discussed in the next section, the procedure for scribing the Leading Edge Reference Line (LERL) uses a different strategy as a first step to avoid multiple contact points when scribing the line. The convention described above would be used if multiple contact points occur even after using that initial step.) We note that GTR 9 specified the “highest points of contact” with the 700 mm straight edge when tracing the side reference line. In the example in figure VI.9, this would actually result in a more inboard point defining the SRL. However, in practice this is unlikely to result in any meaningful difference in the defined Hood Top.

EP19SE24.015

7. Special Provisions for the Leading Edge of the Hood

As explained earlier, NHTSA uses a straight edge to define the LERL of the hood. Similar to the side border, this front border of the hood may have multiple points of contact when using the straight edge held at 40° from the horizontal. If continuous or multiple points of contact result, this NPRM (consistent with the GTR) specifies adjusting the angle of the straight edge from 40° to 50° from the horizontal to try to achieve a single point of contact.

93 94

See figure VI.10 below, provided for illustration purposes. (This also has the effect of extending the LERL forward and thus increasing the headform test area, which NHTSA believes is desirable and consistent with safety.) We note that NHTSA is also proposing objective ways to determine whether there is “continuous contact” or “multiple contact points” for assessing if the straight edge angle must change. Such a provision is not specified in GTR 9. A continuous contact would be established when the vehicle surface is within 0.5 mm of the straight edge for at least 50 mm of the straight edge. Contacts would have to be separated by at least 50 mm on the straight edge to be considered multiple contacts.

Paragraph 3.5. “

Bonnet leading edge reference line

.”

If this happens, the whole leading edge mark-off process is restarted using the 50° incline for the entire leading edge, even though the discrepancy may have occurred at only one spot.

EP19SE24.016

As is the case with the Side Reference Lines, a zigzagging final front border is an acceptable result. If there are gaps in the line, NHTSA would fill in the gaps using a non-stretch wire held taut across the gap in the line. The break is filled by scribing a line created by the projection of the wire vertically downward on the vehicle surface. Any protruding hood ornaments would be removed when drawing the LERL if they have the effect of pushing the border rearward (and reducing the test area).

One additional special provision of the LERL relates to vehicles where the only contact of the straight edge is at its upper tip. Consistent with the GTR, as the straight edge is moved laterally across the front of the vehicle, if the upper tip is the only contact point, the WAD1000 line is the LERL at this location. Additional discussion on this topic is presented later in this document.

B. Hood Area

After identifying the Hood Top, the next step is to establish the “Hood Area.”

The Hood Area (see light grey area in figure VI.11) is enclosed by the intersection of the following borders:

For some vehicles, the Hood Area may be equivalent to the Hood Top. Also, we note that GTR 9 does not define a Hood Area. In GTR 9, the equivalent area would be what GTR 9 refers to the “combined child and adult headform test areas.” We have defined Hood Area for increased clarity.

•

Front border:

the Leading Edge Reference Line (LERL) or the WAD1000 line, whichever is most rearward at the point of measurement;

•

Side border:

Side Reference Lines (SRL).

•

Rear border:

Rear Reference Line (RRL), or the WAD2100 line, whichever is most forward at the point of measurement.

BILLING CODE 4910-59-P

EP19SE24.017

BILLING CODE 4910-59-C

1. Front Border of the Hood Area

Consistent with GTR 9, this NPRM proposes to use the most rearward of either the WAD1000 line or the LERL in determining the front border of what proposed FMVSS No. 228 would call the Hood Area. In the example shown in figure VI.11 the Hood Area (light grey) does not completely cover the Hood Top because the WAD1000 line is rearward of the LERL. The cross hatched area shows the difference between the Hood Top and Hood Area. WAD1000 is just under the average height of a 6-year-old child (a target demographic of the standard), which is 1,150 mm. The drafters of the GTR explained that a WAD of 1,000 mm was selected as the forward boundary because real-world crash data show that over 80 percent of child pedestrian head contacts are above a WAD of 1,000 mm.

Figure VI.11, above, shows an example of the WAD1000 line defining the front edge of the Hood Area, rather than the LERL. As we discuss in section VI.C.1, the front border of the Hood Area could be the front border of the Child Headform Test Area on some vehicles. We also discuss how we are considering shifting the front border of the Child Headform Test Area to increase the area subject to the proposed standard. (Conforming changes would be reflected in the front border of the Hood Area if such a change were made.)

Paragraph 72 of the “Safety Need” section of GTR 9.

https://unece.org/fileadmin/DAM/trans/main/wp29/wp29wgs/wp29gen/wp29registry/ECE-TRANS-180a9e.pdf

2. Side Border of the Hood Area

The side borders for the Hood Area are the SRLs, which are also the side borders for the Hood Top. The length of side borders may differ from the Hood Top on some vehicles since the Hood Area may have different rear and front borders than those of the Hood Top.

3. Rear Border of the Hood Area

Similar to the process for the front border, the first step in establishing the rear border of the Hood Area is to locate the WAD2100 line (WAD2100). This NPRM's regulatory text proposes to use the most forward of either WAD2100 or the Rear Reference Line (RRL)

in determining the rear border of the Hood Area. Strictly speaking, this is different from GTR 9, which defines the rear boundary of the equivalent area (rear reference line for the adult headform) as always being WAD2100. We believe this is an error in GTR 9, because under this reading of the GTR, even if the RRL were forward of the WAD2100 and WAD2100 is in the windshield area (essentially off of the Hood Top), WAD2100 still would be used as the rear border of the area in question. This would affect the calculation of the amount of area that must conform to a HIC1000 level, potentially including part of the windshield or cowl. This outcome is not consistent with our understanding of GTR 9.

As a reminder, the RRL is determined by inserting a 165 mm sphere into the cowl and against the windshield such that the sphere is in contact with the windshield and a point on the surface of the hood (usually the cowl's rear edge).

This NPRM's regulatory text describes using the most forward of either

WAD2100 or the RRL in determining the rear border of the Hood Area. For most passenger cars, WAD2100 falls rearward of the cowl so the rear border would be the RRL. However, WAD2100 could define the rear border on some larger vehicles. Figure VI.12, below, shows an example of the WAD2100 line defining the rear edge of the Hood Area, rather than the RRL. Again, the cross hatched area shows the difference between the Hood Top and Hood Area. As we discuss below, the rear border of the Hood Area may not necessarily be the rear border of the Adult Headform Test Area. In section VI.C.5, we discuss using WAD2500 rather than WAD2100 as the rear reference line for the Adult Headform Test Area. (Conforming changes would be reflected in the rear border of the Hood Area if such a change were made.)

BILLING CODE 4910-59-P

EP19SE24.018

BILLING CODE 4910-59-C

4. Corner Reference Point of the Hood Area

As was the case with the Hood Top, we believe it is also necessary to define a Corner Reference Point for the Hood Area to avoid any ambiguity in pinpointing the intersection of the front and side borders of the Hood Area. Obviously, when the Hood Top and Hood Area share the same front border (LERL), the corner point is the same. However, when the front border of the Hood Area is the WAD1000 line, the corner points will be different, with the Corner Reference Point of the Hood Area being at the intersection of the WAD1000 line and the side border, and the Corner Reference Point of the Hood Top being at the intersection of the LERL and the side border.

C. Defining the Child Headform Test Area and the Adult Headform Test Area

Overview.

Proposed FMVSS No. 228 defines a Child Headform Test Area and an Adult Headform Test Area, which are contained within the Hood Area.

Consistent with GTR 9, under this NPRM the test areas have been separated into child and adult regions because head strikes on the hood in real-world collisions are dependent primarily on the collision speed, the height of the pedestrian, and the shape of the vehicle front-end.

WAD is used for demarcation of the Child and Adult Headform Test Areas because it is an excellent indicator of where a pedestrian's head will strike a hood under a given set of conditions.

100

As noted earlier, this preamble occasionally refers to these two test areas together as the “Child and Adult Headform Test Areas” or “the combined Child and Adult Headform Test Areas.”

Ivarsson BJ, Crandall JR et al (2007), Pedestrian head impact- what determines the likelihood and wrap around distance? Paper No. 07-0373, 20th International Technical Conference on the Enhanced Safety of Vehicles Conference (ESV) in Lyon, France, June 18-21, 2007.

100

The crash scenario represented by the test is a non-braking, 40 km/h impact. The suspension is set up for normal ride attitude, not braking.

Headform HIC Unlimited Areas

The Child and Adult Headform Test Areas are smaller than the Hood Area to account for specified regions that are not subject to HIC limits under the GTR, which we call “HIC Unlimited Area.”

101

The HIC Unlimited Area shares an outer boundary with the Hood Top. Its inner boundary is called the HIC Unlimited Margin. The HIC Unlimited Margin forms the outer boundary of the Child and Adult Headform Test Areas.

101

As explained previously, the standard would provide for HIC Unlimited Areas as a practicability measure to accommodate a manufacturing need to reinforce and stiffen the hood edges.

The Child Headform Test Area (See figure VI.13) is enclosed by the intersection of the following borders:

•

Front border:

HIC Unlimited Margin of the Leading Edge Reference Line.

102

As explained later in this section, this is either the 82.5 mm offset line or the WAD1000 line, whichever is more rearward.

•

Side borders:

HIC Unlimited Margins of the Side Reference Lines.

•

Rear border:

WAD1700 line or the HIC Unlimited Margin of the Rear Reference Line, whichever is most forward at the point of measurement.

The Adult Headform Test Area (See figure VI.13) is enclosed by the intersection of the following borders:

•

Front border:

WAD1700 line.

•

Side borders:

HIC Unlimited Margins of the Side Reference Lines.

•

Rear border:

HIC Unlimited Margin of the Rear Reference Line.

103

BILLING CODE 4910-59-P

EP19SE24.019

BILLING CODE 4910-59-C

The first step in determining the HIC Unlimited Margin would be to establish a reference line by measuring an 82.5 mm (3.25 inches) distance from each point along the four borders of the Hood Top. For convenience, in this preamble we refer to this as “the 82.5 mm offset line.” (See figure VI.14.) For example, the HIC Unlimited Margin of the Side Reference Line is established by following the SRL along the contour of the body in the y-z plane using the equivalent of a taut, 82.5 mm (3.25 inch) graduated wire. The regulatory text describes using the wire to measure the 82.5 mm (3.25 inches) distance over any surface bumps that may be present, such as ornamental trim. Since the wire is taut, it would span any depressions (such as a seam between the hood and fender) between the points on the SRL to the measured points. The wire must not deviate from the y-z plane when establishing the HIC Unlimited Margin of the Side Reference Line. Similarly, an 82.5 mm offset line for the LERL and RRL would be drawn by measuring the prescribed distance from each point along the LERL and RRL along the contour of the body in the x-z plane using a taut, graduated wire.

103

As explained later in this section, this is either the 82.5 mm offset line or the WAD2100 line, whichever is more forward.

EP19SE24.020

1. Front Border of Child Headform Test Area

The front border of the Child Headform Test Area is the HIC Unlimited Margin of the Leading Edge Reference Line, which is the WAD1000 line or the 82.5mm offset line, whichever is most rearward.

104

Figure VI.15 shows an example where the front border of the Child Headform Test Area (right image) is formed by the 82.5 mm offset line and the front border of the Hood Area is the WAD1000 line (left image). As in figure VI.12, the left image shows the Hood Area overlaid on the Hood Top (cross hatch showing the difference), with the Hood Area being smaller because WAD1000 is rearward of the LERL. In the right image we see that the test area begins rearward of the Hood Area front border. The left image shows the borders of the Hood Area (light grey area) and the right image the border of the Child and Adult Headform Test Areas (dark grey). Note that in the right image any area that is not part of the Child and Adult Headform Test Areas is part of the HIC Unlimited area (this includes the light grey and the cross hatched areas).

104

Note that the front border of the Child Headform Test Area is the most forward border of the combined test area.

EP19SE24.021

c. Considerations for the Child Headform Test Area Front Border

The agency believes there are several provisions where it would be worthwhile for FMVSS No. 228 to differ from GTR 9 with respect to the front border of the testable area, particularly for vehicles that are larger or smaller than typical size. NHTSA requests comment on these approaches for possible inclusion in the final rule.

First, with respect to large vehicles, this NPRM's regulatory text for FMVSS No. 228 reflects the provisions of GTR 9 regarding the procedures for testing vehicles with higher front ends, like larger light trucks, but the agency discusses in this section aspects that NHTSA believes may be more appropriate for the U.S. fleet. To begin, the GTR procedure is as follows: When establishing the front border of the relevant Hood Top, Hood Area, and ultimately the Child Headform Test Area, the first step is to use the 1,000 mm straight edge to determine the LERL. As shown in figure VI.16, for passenger car designs, the straight edge is held high enough to engage the vehicle's front end. However, the upper leading edge of the hood for some full-sized pickup trucks exceeds 1,243 mm, which is the highest point of the straight edge from the ground. For these vehicles, the upper tip of the straight edge would be the only point of contact with the vehicle. If this occurs, consistent with S3.5 in GTR 9, by definition, the WAD1000 line becomes the LERL. (This provision may also come into play for flat front EVs.) Thus, the front border of the Child Headform Test Area would be established by the 82.5 mm offset line from the WAD1000 line. In some vehicles this may be in the front grille area.

Large pickups and large SUV comprise about 18 percent of new vehicle sales, and some vehicles are large enough that they will engage the tip of the straight edge in this way, such as the MY 2022 Ford F250.

105

Given the prevalence of large vehicles in the U.S. fleet, we believe there are several points worthy of discussion related to this issue, and related to high or flat front vehicles in general. These are discussed below.

105

2021 Wards Automotive.

EP19SE24.022

i. Extending the Straight Edge

First, it would clearly be possible as a practical matter to extend the straight edge to whatever length necessary to contact the vehicle at the more typical front hood location. However, this may result in loss of a significant amount of testable area in the grille and associated safety benefits. Child and small adult pedestrian heads are more apt to strike the grille than the hood top on these vehicles, so extending the straight edge would reduce the real-world relevance of the test as regards those pedestrian impacts. Therefore, the agency is not inclined to make such an accommodation without a demonstration that subjecting the grille to testing is infeasible, meeting the standard is impracticable, or other such reason. In a section below, we request comment on the practicability of meeting proposed FMVSS No. 228 in the grille area.

ii. NHTSA Seeks a More Consistent Approach

The provision establishing the WAD1000 line as the LERL if the tip contacts the vehicle sets up a provision in the standard that would test vehicles with just slight hood height differences differently. In vehicles such as that shown in the bottom part of figure VI.16, the LERL would be WAD1000 because the tip of the straight edge contacts the vehicle—and, as a result, because WAD1000 is in the grille, the grille would be tested. However, for a vehicle with a slightly lower hood height that just allows the straight edge to make contact with the hood along the straight edge length and not at its tip, the LERL would not drop to the WAD1000 line in the grille area—and so the grille area would not be tested. NHTSA believes a more consistent and reasonable approach could be one that determines the test area using data tied to where head impacts are likely to occur, as opposed to an approach that determines test area by the length of a straight edge. Thus, NHTSA requests comments on an approach that establishes the WAD1000 line as the front border of the test area for all vehicle testing. NHTSA believes this approach is merited as it determines the test area based on where head impacts would occur in the real world, rather than where a straight edge makes contact. The agency poses specific questions at the end of this section and requests comments on using this approach in the final rule.

iii. Impact Angle Considerations

We request comment on the specifics of testing a grille area. As described in the test procedure of the GTR, the child headform is launched at 50 degrees down from the horizontal and would impact a horizontal surface at 40 degrees from a purely perpendicular impact. (The child headform impact angle is illustrated in figure V.3 of this preamble.) Assuming, for simplicity, a vertical front face of a vehicle, this

means the impact would be 50 degrees from purely perpendicular. However, striking a grille in this manner would constitute a slightly less direct impact and presumably a less severe test. We believe that, in a real-world impact, the head of a child striking such a high front end vehicle would have a trajectory more in line with the velocity vector of the vehicle than the current launch angle of the child headform. The Euro NCAP procedure and NHTSA's NCAP RFC allow for test points on the front surface of the vehicle. Euro NCAP and the NCAP RFC make an adjustment to the impact direction to 20 degrees when forward of the LERL so as to produce a more perpendicular impact. Additionally, if the LERL is between WAD930 and WAD1000, Euro NCAP monitors this location with a 20-degree impact test performed at the LERL.

106

NHTSA plans to conduct research on headform testing in the grille area of some pickup trucks using the proposed FMVSS No. 228 protocol to assess its practicality, as well as the merits of a more direct (perpendicular) impact. As discussed in the next section, depending on the results, the final rule may adjust the impact angle of the headform when the test is conducted in the grille area.

106

Monitors means the results could be called out but are not part of the Euro NCAP scoring. See, Technical Bulletin 019—Headform to Bonnet Leading Edge.

https://www.euroncap.com/en/for-engineers/supporting-information/technical-bulletins/

. This bulletin explains that the result of this test will be monitored against a HIC value of 650. Where a “poor” test result has been achieved, Euro NCAP may choose to comment on this alongside the normal pedestrian protection score. The results of these tests will not be reflected in the pedestrian protection score or any other part of the overall assessment.

iv. Apportioning of Test Area to HIC Levels

For these high front and flat front vehicles, the apportioning of the amount of the test areas that must have a HIC1000 or less merits discussion. As previously mentioned and discussed in more detail in section VII of this preamble, the portion of the Combined Child and Adult Headform Test Areas that must meet the HIC1000 provision must be at least the numerical value of two-thirds of the Hood Area placed inside of the Child and Adult Headform Test Areas. Because this two-thirds calculation is made on the basis of a two-dimensional projection on to a horizontal plane, if some of the Child Headform Test Area could be on a front surface of a vehicle that is more vertical than horizontal, this area would not be added to the Hood Area calculation simply due to the method of calculation using the two-dimensional projection onto a horizontal plane. The concern here is that this vertical test area, even if considered part of the headform test area, would not be considered in calculating the amount of required HIC1000 area. Stated another way, the vertical test area, or an equivalent amount, would not have to meet HIC1000; it could be assigned only HIC1700, which would result in the vehicle providing a lowered level of head protection. (Comments are requested on this issue in the next section.)

v. Shifting the Test Border Forward

This point relates to large vehicles in general where the upper portion of the straight edge, but not the tip, makes contact with the vehicle. For these vehicles, WAD1000 could be in the grille area,

107

but under the GTR, the Child Headform Test Area begins well beyond WAD1000, because the test area would begin at the 82.5 mm offset line as it is more rearward than WAD1000. NHTSA is concerned that, for such vehicles, under the GTR provisions the agency would not be testing the areas of the hood that could be struck by children of the stature of a 6-year-old. As mentioned above, the NCAP RFC procedure allows for testing to WAD1000, even when WAD1000 is forward of the LERL. In 2014, NHTSA investigated how the different interpretations of the impact point targeting methods could change the actual testable area of a hood.

108

Headform tests were performed along the forward-most border of the test zone and, depending on which targeting method was used, the actual point of first contact of the headform with the hood was either on the border or slightly in front of the border (see table VI.1). Although HIC was found to increase at first contact locations in front of the border, the increase did not appear to have affected conformance,

i.e.,

impact points conforming to either HIC1000 or HIC 1700 remained below the required HIC limit. Based on these results, NHTSA believes a requirement that vehicles meet FMVSS No. 228 with a 30 mm shift of the forward-most border seems practicable. We request comments on this issue. We note that in section VII and XI of this preamble, we also discuss the issue of whether proposed FMVSS No. 228 should reduce or eliminate the areas in which, under the GTR, HIC is not assessed (the HIC Unlimited Area). Reducing or eliminating the HIC Unlimited Area would also shift the forward-most border forward.

107

GTR data indicate that 6-year-old child head impacts start at about WAD1000.

108

Details of these tests can be found in: Suntay B and Stammen, JA (August 2018), Vehicle hood testing to estimate pedestrian headform reproducibility, GTR 9 test procedural issues, and U.S. fleet performance. Docket NHTSA-2008-0145-0014.

Table VI.1—HIC at Points Tested on the Forward-Most Border and at a Point Shifted Slightly Ahead of the Border

Vehicle

HIC comparison

At forward-most border per GTR 9

At point shifted about 30 mm

forward of border

HIC %

increase

2010 Buick Lacrosse

1026

1041

1.5

2010 Kia Forte

626

703

12.3

2010 Acura MDX

1283

1326

3.4

2010 Hyundai Tucson

638

670

5.0

2011 Jeep Grand Cherokee

651

874

34.3

2011 Honda Odyssey

1302

1379

5.9

vi. Testing Forward of WAD1000 for Small Vehicles

Regarding smaller vehicles, the NPRM's regulatory text reflecting the GTR specifies that the forward border of the required test area would be the 82.5 mm offset line or WAD1000, whichever is most rearward. Under this proposed provision, requirements for head protection would start at WAD1000 for most small vehicles as the WAD1000 line is usually more rearward than the 82.5 mm offset line. However, for many smaller vehicles WAD1000 is far up the hood, which means much of the hood (the forward portion) would not be subject to any headform testing. It does not appear there are practicability barriers to headform testing of the hood on small vehicles, because comparable areas of the hood on larger vehicles would be regulated under the proposed standard and thus subject to headform testing. Testing forward of WAD1000 would potentially add to the protection of children with a standing height of less than 1,000 mm. As discussed below, to increase the safety benefits of the rule, we are considering an alternative provision that would test forward of WAD1000. NHTSA requests comment on this issue.

Request for Comment on Modifying the Forward Border

Based on the above discussion, NHTSA requests comments on the questions below to help the agency decide whether a final rule should identify the forward border differently. Please comment on the potential gain in safety benefits as well as any potential practicability, cost, or technical issues.

• The NPRM's regulatory text reflects the GTR 9 provision that accounts for the situation where the tip of the 1,000 mm straight edge defines the LERL (rather than a point further down along the straight edge), such as when the tip of the straight edge could make first contact with the grille of a subject vehicle. In this situation, the WAD1000 line becomes the LERL. This means that the testable area could potentially include the grille area of the vehicle (

i.e.,

headform impacts could be conducted on the grille area of the vehicle). We request comment on adjustments to the launch angle

109

for such impacts, to potentially make them more perpendicular to the impacted surface to replicate a real-world impact more accurately. What impact point condition/location should trigger a change in impactor launch angle? Additionally, should the estimate of Hood Area be modified if some portion of the Hood Top is in the grille area, such as using a test area projection onto a vertical plane for the more vertical tests areas?

109

The Child Headform is launched at 50 degrees down from the horizontal and would impact a vertical surface at 50 degrees from a purely perpendicular impact.

• There may be large vehicles with a hood height slightly lower than those where the straight edge tip contacts the vehicle first, such that the provision to drop the LERL to WAD1000 is not triggered. Additionally, the NPRM's regulatory text (reflecting the GTR) specifies that, for large vehicles in general, the Child Headform Test Area begins well rearward of WAD1000—

i.e.,

well rearward of where a child's head is likely to strike. However, NHTSA requests comments on changing the front border of the Child Headform Test Area to be either the Offset Line or WAD1000, whichever is

forward-most,

rather than rearmost. An outcome of this change would be that, in some cases, the test area would be forward of the Hood Top and conforming changes would need to be made to maintain the test area within the Hood Top. We note that the Euro NCAP and the NCAP RFC allow for testing at WAD1000, even if it is forward of the LERL. Euro NCAP monitors performance at the LERL as far forward as WAD930 if the LERL is forward of WAD1000, although this does not factor into the score.

• For many smaller vehicles the forward line where testing is required is at WAD1000, far behind the LERL, which means much of the hood (the forward portion) would not be subject to headform testing. We note that subjecting these forward areas of the hood to the standard may benefit children smaller than the average 6-year-old. A potential way to subject the forward areas to testing could be the same as that suggested above for larger vehicles,

i.e.,

selection of the test area boundary based on the

forward-most

of the WAD1000 or of the Offset Line, rather than the

rearward-most

. We ask for comment on this issue in the context of smaller vehicles.

• As discussed above, another alternative on which we request comment involves how the GTR determines the HIC Unlimited Margin for the front and sides. (Impacts in the HIC Unlimited Margin are not subject to any HIC limit.) The NPRM's regulatory text reflects the GTR's specification that the margin would be determined using an 82.5 (3.25 inch) mm taut wire, but NHTSA finds merit in using a 50 mm (1.97 inch) taut wire instead to increase the testable area, and reduce the allowable area of the HIC Unlimited Margin.

2. Transition Between Child and Adult Headform Test Areas at WAD1700

Consistent with the GTR, proposed FMVSS No. 228 would separate the Child Headform Test Area from the Adult Headform Test Area at WAD1700. For many smaller vehicles, it is possible that there would be no Adult Headform Test Area at all when the transition between the child and adult test areas is drawn at WAD1700. Consistent with the GTR, proposed FMVSS No. 228 would require that, if there is only a Child Headform Test Area, the requirements that applied to the combined Child and Adult Headform Test Area are applied to the Child Headform Test Area alone. For example, at least two-thirds of the numerical value of the Hood Area, when placed within the boundary of the Child Headform Test Area (as opposed to the combined areas) must not exceed HIC of 1000 using the child headform. For the remaining area the HIC shall not exceed 1700.

This NPRM uses WAD1700 to transition between the Adult and Child Headform Test Areas because GTR data indicate that 6- to 15-year-old child head impacts start at about WAD1000 and end at WAD1700. A 5th percentile female has a standing height of an average 12-year-old child and would likely have a head impact within the Child Headform Test Area. Consistent with this, figure VI.17 below from the Pedestrian Crash Data Study (PCDS) shows that for all adults, impacts start at about WAD1400 and end at WAD2400. PCDS shows that about 70% of all adult pedestrian head impacts are between WAD1000 and WAD2100. Separating the genders, about half of adult female and one third of adult male head impacts are between WAD1000 and W1700 (not depicted in figure VI.17). As shown in figure VI.17, the WAD1700 represents the 75th percentile for children under age 10 and the 25th percentile for all adults. Because stature distribution has remained stable over the past two decades

110

and because WAD has been shown to depend primarily on the pedestrian's stature for a particular vehicle impact speed,

111 112 113

this WAD distribution would still be representative today.

110

Fryar CD, Kruszon-Moran D, Gu Q, Ogden CL. Mean body weight, height, waist circumference, and body mass index among adults: United States, 1999-2000 through 2015-2016. National Health Statistics Reports; no 122. Hyattsville, MD: National Center for Health Statistics. 2018.

111

Ivarsson J, et al. “Pedestrian Head Impact—What Determines the Likelihood and Wrap Around Distance?”, 20th Enhanced Safety of Vehicles Conference (2007); paper no. 07-0373.

112

Kiuchi T, et al. “Comparative Study of VRU Head Impact Locations,” Sixth Expert Symposium on Accident Research (ESAR). Hanover, Germany (2014).

113

Otte, D. “Wrap Around Distance WAD of Pedestrian and Bicyclists and Relevance as Influence Parameter for Head Injuries,” SAE Technical Paper 2015-01-1461, 2015.

EP19SE24.023

Data show that child-adult overlapping of impacts occurs between 1400 and 1700 mm. The drafters of the GTR considered whether to use a test method where the child and adult test areas overlap or whether a step change should be used, and where it should be drawn. The goal was to ensure that the transition area would provide protection against both child and adult head impacts. The drafters considered an approach to specify a test area (transition zone) in which both a child headform and an adult headform would be used to assess compliance, because both children and adults strike this area. Such a transition zone could, for example, be WAD 1400—WAD1700 or WAD1500—WAD1700. They also considered, and ultimately adopted, a sudden transition (step change) approach. However, the NCAP RFC and Euro NCAP test procedures have adopted a transition zone between WAD1500—WAD1700, where both impactors must be used if the RRL is between WAD1500 and WAD1700.

The rationale supporting a step change approach is that a sudden step change in hood performance is not

likely to be engineered into the design of a hood, and that a step change approach reduces the need to conduct unnecessary headform tests. In practice, a sudden step change produces a hood design with an area around the transition line that is safe for both child and adult pedestrians. Therefore, it was decided that a hood designed for overlapping child-adult safety is effectively achieved without the need to specify the use of two headforms. Further, a defined boundary at 1,700 mm provides a clearer approach. The GTR adopted the step change approach with a transition at WAD1700, which biases protection towards children. That is, the use of WAD1700 makes more of the hood tuned to protect a child's head than an adult head. Rather than having to design hoods for both head masses, the use of a non-overlapping transition at WAD1700 allows safety in the transition area to be optimized for the lighter headform.

Request for Comment on the Transition Zone

• NHTSA tentatively agrees with the above reasons and has drafted the regulatory text of proposed FMVSS No. 228 to specify a non-overlapping transition from the Child Headform Test Area to the Adult Headform Test Area at WAD1700. However, we request comments on the merits of a transition zone. We would like to know more about the degree to which a step change approach addresses safety for both adults and children for vehicles that have sharp changes in structure, such as the joint between the rear of the hood and the cowl, which may occur along the transition line. This is indeed the case for many smaller vehicles which have no Adult Headform Test Area at all when the transition is drawn at WAD1700. While this helps with design feasibility for such vehicles (requirements apply for the lighter headform only), it may reduce the safety of such vehicles for shorter adult pedestrians because the hood may not provide sufficient penetration depth for the heavier adult headform. We therefore seek comment on other options for FMVSS No. 228. These options may include a revised procedure in which the adult/child border is drawn at a different WAD and use of a transition area that is tested with both headforms.

3. Rear Border of Adult Headform Test Area

Consistent with GTR 9, the rear border of the Adult Headform Test Area is the HIC Unlimited Margin of the Rear Reference Line, which is the WAD2100 line or the 82.5mm offset line, whichever is more forward. WAD2100 is based on the average height of a 50th percentile adult male, which is about 1750 mm. This height is about the 97th percentile for adult females in the U.S.

114

Based on 2007-2010 NHANES from

https://tools.openlab.psu.edu/tools/explorer.php.

d. Considerations for the Adult Headform Test Area Rear Border; Request for Comment

NHTSA is considering several changes to the GTR approach related to the rear border of the Adult Headform Test Area to increase the test area. These considerations offer the potential of providing increasing pedestrian protection to individuals taller than the average male, and to individuals involved in higher speed impacts.

1. First, we are considering including headform testing of the windshield. This NPRM's regulatory text does not include testing of the windshield, A-pillars or top edge of the windshield, which is reflective of GTR 9's text. The GTR excludes the A-pillars and top edge of the windshield from the test area because of practicability reasons, and NHTSA generally agrees with excluding those areas. It is difficult to reduce the stiffness of the windshield frame because it serves as a support structure and helps to ensure the integrity of the occupant compartment. Furthermore, in the lower windshield area the requisite deformation space to meet HIC is restricted by the dashboard and instrument panel. Some components must be positioned in the dashboard and instrument panel to provide occupant protection (

e.g.,

air bags) and crash avoidance safety,

e.g.,

defrosting requirements, forward-view sensors for automatic emergency braking, and rearview cameras. In addition, the structural components of the dashboard comprise important load paths in front and side crashes that contribute to occupant crash protection.

The GTR drafters excluded the windshield for different reasons, finding that the windshield itself does not cause severe injuries and therefore the number of casualties averted would be very low. The center of the windshield—away from the edges—generally produces good safety scores, although impacts near the A-pillars universally produce poor results. This is consistent with real-world data which show that fatal injuries are more common when the head strikes the windshield frame rather than the center area.

115

Fredriksson R (2011), Priorities and potential of pedestrian protection—accident data, experimental tests, and numerical simulations of car-to-car pedestrian impacts. Doctoral Thesis, Department of Public Health, Karolinska Institutet, Stockholm, Sweden, 2011.

Nonetheless, NHTSA is concerned that head-to-windshield impacts are associated with a high incidence of pedestrian injuries. One reason is that a head-to-windshield impact may have a higher velocity than a head-to-hood impact.

116

Kerrigan J, Arregui C, Crandall JC (2009), Pedestrian head impact dynamics: comparison of dummy and PMHS in small sedan and large SUV impacts, Paper No. 09-0127, 21st International Technical Conference on the Enhanced Safety of Vehicles Conference (ESV)—International Congress Center Stuttgart, Germany, June 15-18, 2009.

NHTSA has also observed that vehicle designs have changed in recent years in that windshields are more forward on the hood, where the cowl may begin at WAD1700. WAD1700 separates the Child Headform Test Area from the Adult Headform Test Area. Because the area rearward of the cowl is excluded from the headform test area, these vehicles have hoods that would only have a Child Headform Test Area and would be tested only with a child headform. NHTSA is concerned that these designs may be particularly detrimental to shorter adult pedestrians who are more apt to strike the hood near the cowl than in the case of designs of predecessor vehicles whose cowls began at a higher WAD measurement. Extending the test area into the windshield may serve to disincentivize such designs by eliminating the compliance advantage that may come with limiting the hood size to WAD1700. Further, the windshield itself on these vehicles tends to be more horizontal than vertical, and so a larger portion of the windshield lies directly above and near the dashboard panel where there is less penetration depth to protect the head. The extended windshield (

i.e.,

a windshield placed immediately beyond WAD1700) may also be stiffer than the portion of the hood that would otherwise have covered the same area. Extending the test area into the windshield may serve to protect pedestrians who may strike this stiffer portion of the windshield.

NHTSA has also observed the development of automated rideshare vehicles and other modern EVs with very flat fronts, with the base of the windshield or windshield-like areas at very small WAD locations compared to traditional vehicles. For such vehicles, exclusion of the windshield-like areas would essentially permit the vehicle to not provide any form of pedestrian head protection.

Finally, as we noted above, some of these automated vehicles appear to have

a windshield-like area, but it is not a windshield in the traditional sense since it is not transparent. For such vehicles, the RRL would not exist since it is determined by inserting a 165 mm sphere into the cowl and against the windshield such that the sphere is in contact with the windshield and a point on the surface of the hood (usually its rear edge). For such vehicles, the rear boundary of the Hood Area and Adult Headform Test Area would be defined by the WAD2100 line. Comments are requested on how the test area should be determined for vehicles with no traditional windshield and on the merits of determining the rear boundary of the Hood Area and Adult Headform Test Area by WAD2100 for such vehicles, as would be the case for the proposed regulatory text.

As for practicability, NHTSA has performed eleven tests into the windshield as part of the testing documented in table VII.1, below. Of those eleven tests, nine had HIC below 1000 and the other two tests were HIC below 1700, which support a finding that testing of at least some portion of the windshield may be reasonable and practicable.

It is the agency's understanding that UNECE Reg. No. 127 has a proposal to specifically add the windshield as a new test area.

117

This area is bound, in the front, by a line 100 mm rearward of the blacked-out (non-transparent) portion of the windshield base and in the rear by WAD2500 or a line 130 mm forward of the rear edge of the windshield, whichever is more forward at a given lateral position. The side border is 100 mm inside of the blacked-out area. Adding the windshield to UNECE Reg. No. 127 would indicate the provisions of GTR 9 are appropriate for the windshield.

117

ECE/TRANS/WP.29/GRSP/2021/28.

• Given the above, there appears to be merit to including the windshield in a test area for FMVSS No. 228. The regulatory text of this NPRM does not include the windshield, but NHTSA is considering language for a final rule that would include the windshield. The NCAP RFC and various international NCAP programs that assess pedestrian safety (Euro NCAP, Japan NCAP, Korea NCAP, and Australian NCAP) include a head-to-windshield impact test area. In addition, a UNECE Reg. No. 127 proposal also includes the windshield for testing.

2. The next subject for consideration is the limitation of testing beyond WAD2100. Consistent with GTR 9, this NPRM's regulatory text states that the rear border of the Adult Headform Test Area is either WAD2100 or the HIC Unlimited Margin of the Rear Reference Line, whichever is more forward. However, the ECE proposal mentioned above changes WAD2100 to WAD2500. That is, the rear border of the Adult Headform Test Area (“Adult Bonnet Top Headform Test Area” in the ECE proposal) would be changed from the forwardmost of WAD2100 or the 82.5 mm offset line, to the forwardmost of WAD2500 or the 82.5 mm offset line. The change to WAD2500 would increase the test area. We are also aware of similar changes to the Euro NCAP requirements being implemented in 2023, with the area between WAD2100 and WAD2500 being referred to as the Cyclist Zone.

118

WAD2500 might extend past the windshield to the roof, and, under Euro NCAP procedures, the A-pillars are tested. Any impacts to the roof under Euro NCAP procedures involve a 45-degree angle rather than 65 degrees. We are considering similarly changing WAD2100 to WAD2500 for FMVSS No. 228.

118

Euro NCAP Vulnerable Road User Testing Protocol

https://cdn.euroncap.com/media/70319/euro-ncap-vru-testing-protocol-v901.pdf.

The specification of WAD2100 recognizes that the point of head contact—relative to the height of the pedestrian—moves further rearward as pedestrian stature increases. WAD2100 corresponds to the typical head impact location of a pedestrian with a height of 1,750 mm for a vehicle speed of 40 km/h. A height of 1,750 mm is approximately the height of a 50th percentile male. For most passenger cars and minivans, WAD2100 lies rearward of the Rear Reference Line (RRL) (which is at the cowl) so WAD2100 would not be consequential as it would not be used to define the rear border of the hood area. However, for some larger vehicles in the U.S., the WAD2100 line can be forward of the RRL, which means that WAD2100 would be the rear border of the testable area of the hood even though there could be parts of the hood rearward of that WAD2100 line.

119

NHTSA recognizes that moving the WAD line rearward to account for head impacts rearward of WAD2100 could bear on other aspects of the test procedure, such as the velocity of the headform impact in the test, because actual pedestrian head impact velocities are generally higher at WADs greater than 2100 mm. This means that, if the WAD line were moved rearward of WAD2100, the agency would carefully consider whether adjustments would be appropriate to the test procedure to ensure the continued relevance of the procedure relative to a real-world impact at WADs greater than 2100 mm.

• We seek comment on moving the rear boundary of the test area consistent with using WAD2500 as the reference, rather than WAD2100. Such a change has been proposed for UNECE Reg. No. 127 and Euro NCAP. We also seek comment on the need for a modified impact angle for the roof, if moving to a WAD2100 boundary results in headform testing in the A-pillar or roof areas.

3. Another issue that arises in defining the Adult Headform Test Area rear boundary is that the GTR uses the

most forward

of either WAD2100 or the 82.5 mm offset line. Figure VI.18 shows an example where the WAD2100 is the rear boundary of the Adult Headform Test Area. For the final rule, NHTSA is considering enlarging the test area rearward by considering the

most rearward

of these borders.

• Regardless of any change to the WAD reference, we request comment on using the most

rearward

of the WAD line or offset line to define the rear boundary of the Adult Headform Test Area, rather than using the line that is most forward.

4. We are also considering reducing the HIC Unlimited Area by using a 50 mm (1.97 inch) offset line rather than an 82.5 mm (3.25 inch) offset line at the rear of the Hood Top. This HIC Unlimited Margin at the rear of the Hood Top was originally written into the GTR to prevent a test anomaly where the headform could hit the windshield and the hood simultaneously. However, NHTSA believes that the use of the 165 mm sphere to define the RRL works adequately to prevent situations where the headform could contact the windshield and hood simultaneously. We also note that the NCAP RFC and Euro NCAP do not consider impact points on the hood that are a distance less than 50 mm from the Side Reference Line (SRL) measured in the lateral direction;

i.e.,

they use what amounts to a 50 mm offset line rather than an 82.5 mm offset.

• Accordingly, while the regulatory text of this NPRM uses an 82.5 mm Offset Line, NHTSA is considering using a 50 mm Offset Line rather that an 82.5 mm Offset Line to define the rear HIC Unlimited Margin. The reduced Offset Line would make more of the hood on larger vehicles subject to headform testing. NHTSA requests comments on the merits of the agency's adopting a 50 mm Offset Line in the final rule.

5. Finally, we are considering and request comments on the merits of including the entire Hood Top as the testable area. This would mean the elimination of the HIC Unlimited Area completely, of both the Child and Adult Headform Test Areas, and expansion of the front test border to the LERL and the rear border to the RRL. We discuss this

in more detail in section XI, Considered Alternatives.

EP19SE24.024

4. Corner Reference Point of the Child Headform Test Area

Finally, we believe it is also necessary to define a corner reference point for the test areas (specifically the Child Headform Test Area), just as it is for the Hood Area. The rationale is the same as for the Hood Area,

i.e.,

we need to clearly define the extent of the test area. There may be multiple intersections between the front border of the Child Headform Test Area (HIC Unlimited Margin of the LERL) and the side border of the Child Headform Test Area (HIC Unlimited Margin of the SRL). The definition would make clear that we would be using the most outboard intersection when there are multiple intersections of the front and side borders. This term would be called the “Corner Reference Point of the Child Headform Test Area.”

VII. Proposed Requirements and Assessing Compliance

A. Amount of Hood Area That Must Conform to HIC1000

Consistent with GTR 9, the regulatory text of this NPRM prescribes the amount of the Child and Adult Headform Test Areas that must conform to a HIC1000 limit (HIC1000 Area). The remainder of the Child and Adult Headform Test Areas must be able to conform to a HIC1700 limit (HIC1700 Area).

The basis for the minimum HIC1000 Area is the size of the Hood Area. After the Hood Area is determined, the performance requirements would be applied as follows:

(1) The numerical value of two thirds of the Hood Area is calculated. At least this amount of area, when placed within the boundary of the Combined Child and Adult Headform Test Area, must not exceed HIC1000.

120

This text is long and has been trimmed here. Open the source document for the complete record.

This is a copy of a public record, reproduced as it was published. It is not legal advice, and it may not be the version a court would rely on. Check the official source before you cite it.