Document ID: NHTSA-2023-0031-0001
Agency: nhtsa
Document Type: Proposed Rule
Title: Anthropomorphic Test Devices: Test Device for Human Occupant Restraint 50th Percentile Adult Male Test Dummy; Incorporation by Reference
Posted Date: 2023-09-07T04:00Z

[Federal Register Volume 88, Number 172 (Thursday, September 7, 2023)]
[Proposed Rules]
[Pages 61896-61949]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2023-19008]

[[Page 61895]]

Vol. 88

Thursday,

No. 172

September 7, 2023

Part VI

 Department of Transportation

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National Highway Traffic Safety Administration

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49 CFR Part 572

Anthropomorphic Test Devices; THOR 50th Percentile Adult Male Test 
Dummy; Incorporation by Reference; Proposed Rule

  Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / 
Proposed Rules  

[[Page 61896]]

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DEPARTMENT OF TRANSPORTATION

National Highway Traffic Safety Administration

49 CFR Part 572

[Docket No. NHTSA-2023-0031]
RIN 2127-AM20

Anthropomorphic Test Devices; THOR 50th Percentile Adult Male 
Test Dummy; Incorporation by Reference

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

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes to amend NHTSA's regulations to include 
an advanced crash test dummy, the Test Device for Human Occupant 
Restraint (THOR) 50th percentile adult male (THOR-50M). The dummy 
represents an adult male of roughly average height and weight and is 
designed for use in frontal crash tests. NHTSA plans to issue a 
separate NPRM to amend Federal Motor Vehicle Safety Standard (FMVSS) 
No. 208, ``Occupant crash protection,'' to specify the THOR-50M as an 
alternative (at the vehicle manufacturer's option) to the 50th 
percentile adult male dummy currently specified in FMVSS No. 208 for 
use in frontal crash compliance tests.

DATES: You should submit your comments early enough to be received not 
later than November 6, 2023.
    Proposed Effective Date: Since this rulemaking action would not 
impose requirements on anyone, we are proposing that the final rule 
would be effective on publication in the Federal Register.

ADDRESSES: You may submit comments electronically to the docket 
identified in the heading of this document by visiting the Federal 
eRulemaking Portal at http://www.regulations.gov. Follow the online 
instructions for submitting comments.
    Alternatively, you can file comments using the following methods:
     Mail: Docket Management Facility: U.S. Department of 
Transportation, 1200 New Jersey Avenue SE, West Building Ground Floor, 
Room W12-140, Washington, DC 20590-0001.
     Hand Delivery or Courier: West Building Ground Floor, Room 
W12-140, 1200 New Jersey Avenue SE, between 9 a.m. and 5 p.m. ET, 
Monday through Friday, except Federal holidays. To be sure someone is 
there to help you, please call (202) 366-9826 before coming.
     Fax: (202) 493-2251.
    Instructions: All submissions must include the agency name and 
docket number or Regulatory Information Number (RIN) for this 
rulemaking. For detailed instructions on submitting comments and 
additional information on the rulemaking process, see the Public 
Participation heading of the Supplementary Information section of this 
document. Note that all comments received will be posted without change 
to http://www.regulations.gov, including any personal information 
provided. Please see the Privacy Act heading below.
    Docket: For access to the docket to read background documents or 
comments received, go to http://www.regulations.gov. You may also 
access the docket at 1200 New Jersey Avenue SE, West Building, Room 
W12-140, Washington, DC 20590, between 9 a.m. and 5 p.m., Monday 
through Friday, except Federal Holidays. Telephone: 202-366-9826.
    Confidential Business Information: If you claim that any of the 
information in your comment (including any additional documents or 
attachments) constitutes confidential business information within the 
meaning of 5 U.S.C. 552(b)(4) or is protected from disclosure pursuant 
to 18 U.S.C. 1905, please see the detailed instructions given under the 
Public Participation heading of the Supplementary Information section 
of this document.
    Privacy Act: Please see the Privacy Act heading under the 
Regulatory Analyses section of this document.

FOR FURTHER INFORMATION CONTACT: For non-legal issues, you may contact 
Mr. Garry Brock, Office of Crashworthiness Standards, Telephone: (202) 
366-1740; Email: [email protected]; Facsimile: (202) 493-2739. For 
legal issues, you may contact Mr. John Piazza, Office of Chief Counsel, 
Telephone: (202) 366-2992; Email: [email protected]; Facsimile: (202) 
366-3820. The address of these officials is: the National Highway 
Traffic Safety Administration, 1200 New Jersey Avenue SE, Washington, 
DC 20590.

SUPPLEMENTARY INFORMATION:

Table of Contents

I. Executive Summary
II. Background
III. Design, Construction, and Instrumentation
    A. Anthropometry
    B. Technical Data Package
    C. Head and Face
    D. Neck
    E. Chest
    1. Design
    2. Instrumentation
    F. Shoulder
    1. Alternate Shoulder Specification
    2. Shoulder Slip
    G. Hands
    H. Spine
    I. Abdomen
    J. Pelvis
    K. Upper Leg
    L. Knee
    M. Lower Leg
    N. Data Acquisition System
IV. Biofidelity
V. Qualification Tests
    A. Head Impact
    B. Face Impact
    C. Neck
    D. Upper Thorax
    E. Lower Thorax
    F. Abdomen
    G. Upper Leg
    H. Knee and Lower Leg
VI. Repeatability and Reproducibility
    A. Qualification Tests
    B. Sled Tests
    1. Methodology
    2. Thoracic Injury Criteria Development Sled Tests
    3. Low-Speed Belted Sled Tests
    4. Low-Speed Unbelted Sled Tests
VII. Overall Usability and Performance
    A. Assembly and Qualification
    B. Durability and Maintenance
    1. Elevated Energy Qualification Test Series
    2. Oblique OMDB Test Series
    3. FMVSS No. 208 Unbelted Vehicle Crash Tests
    C. Sensitivity to Restraint System Performance
VIII. Intellectual Property
IX. Consideration of Alternatives
X. Lead Time
XI. Incorporation by Reference
XII. Regulatory Analyses
XIII. Public Participation
Proposed Regulatory Text

I. Executive Summary

    This document proposes to amend NHTSA's regulation on 
anthropomorphic test devices--or, more colloquially, crash test 
dummies--to include an advanced crash test dummy, the Test Device for 
Human Occupant Restraint (THOR) 50th percentile adult male (THOR-50M). 
The dummy represents an adult male of roughly average height and weight 
and is designed for use in frontal crash tests.
    Crash test dummies are complex instruments that simulate the 
response of a human occupant in a crash. Each type of test dummy is 
designed for use in specific types of crashes (for instance, frontal or 
side) and is instrumented with sensors to measure the forces that would 
have been experienced by a human occupant in a similar crash in the 
real world. These measurements are then used to assess the potential 
for injury.
    Crash test dummies are used by NHTSA and by the broader vehicle 
safety community in a variety of ways.

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NHTSA uses crash test dummies to test vehicles for compliance with 
Federal Motor Vehicle Safety Standards (FMVSSs) and to determine 
vehicle crashworthiness ratings for the New Car Assessment Program's 
(NCAP) 5-Star Safety Ratings, as well as to conduct vehicle safety 
research. Crash test dummies are also used by regulatory authorities in 
other countries and regions, third-party vehicle rating programs, motor 
vehicle and equipment manufacturers, and others to evaluate vehicle 
safety and design safer vehicles and equipment.
    The dummies NHTSA currently uses in FMVSS compliance testing and 
NCAP are documented in 49 CFR part 572, Anthropomorphic Test Devices. 
Part 572 sets out detailed design information, including engineering 
drawings and procedures for assembly and inspection. These are intended 
to describe the dummy with sufficient detail so that it is an objective 
measuring tool that produces consistent responses. NHTSA has codified 
numerous dummies that range in sex, size, age, and measurement 
capability. This includes dummies representing midsize adult males, 
small-stature adult females, infants, toddlers, and older children.\1\ 
These dummies are meant to provide a range of body types in order to 
maximize data and test results that can assess injury and fatality 
risks in a range of crash outcomes. The 50th percentile male dummy 
currently defined in Part 572 for frontal impacts is the Hybrid III-
50M, which NHTSA uses to test for compliance with the frontal crash 
test requirements in FMVSS No. 208, ``Occupant crash protection'' and 
to rate vehicles for NCAP. NHTSA added the HIII-50M to Part 572 in 
1986.
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    \1\ This reflects a ``bookend'' approach to testing vehicles for 
crashworthiness, in which a range of occupant types, bookended by an 
average male and a small-stature female, is tested. NHTSA is 
currently supporting research to assess the possible benefits of 
developing new crash test dummies, such as a 50th percentile female 
crash test dummy.
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    NHTSA is continually researching and improving its test dummies and 
has been researching advanced test dummies since the implementation of 
the HIII-50M. An initial THOR-50M design was published in 2001. There 
are currently two different THOR dummies, the THOR-50M, and one under 
development that represents a small-statured adult female, the THOR 5th 
percentile adult female (THOR-05F). Although this proposal is limited 
to the THOR-50M, we anticipate publishing a rulemaking proposal in the 
near future to add the THOR-05F to Part 572.
    The THOR-50M improves on the HIII-50M in a number of ways. It 
responds more like a human occupant in a crash and its advanced 
instrumentation enables it to more accurately measure the forces acting 
on the dummy. As a result, it is better able to predict the risk of 
injury to a human occupant. This should help vehicle designers develop 
and test improved occupant restraint systems (e.g., advanced seat belts 
and air bags) as well as the types of novel vehicle seating 
configurations likely to be used in highly automated vehicles.
    NHTSA has tentatively concluded that the THOR-50M is sufficiently 
biofidelic, exhibits repeatable and reproducible performance, and is 
sufficiently durable. As such, we believe that it would be suitable for 
use in regulatory compliance testing and is therefore suitable for 
incorporation into Part 572. NHTSA and others have already taken 
advantage of the THOR-50M's advanced capabilities. NHTSA, vehicle and 
restraint manufacturers, and vehicle safety researchers have used the 
THOR-50M to evaluate vehicle crashworthiness and develop occupant 
protection countermeasures for frontal and oblique crashes. The 
European New Car Assessment Programme (Euro NCAP) has officially 
adopted the THOR-50M and is currently rating vehicles using the dummy. 
Moreover, the Economic Commission for Europe is considering adopting 
the THOR-50M for use in frontal crash testing under its vehicle safety 
regulations.
    NHTSA expects a variety of benefits from incorporating the THOR-50M 
into Part 572. The definition of the THOR-50M in Part 572 will enable 
its use in regulatory and consumer information programs, both within 
NHTSA and externally. NHTSA believes that the THOR-50M's enhancements 
will lead to more effective restraint system designs and more 
informative comparisons of the safety of different vehicles. Because of 
this--as well as the fact that manufacturers are already using the 
dummy--we believe vehicle manufacturers would choose to certify 
vehicles to FMVSS No. 208 using the THOR-50M if given the option. This 
would enable manufacturers to streamline testing by using the same 
dummy for research and development and to verify compliance. NHTSA 
anticipates issuing a proposal in the near future to amend FMVSS No. 
208 to specify the THOR-50M as an alternative (at the vehicle 
manufacturer's option) to the HIII-50M test dummy for use in frontal 
crash compliance tests. There would be other benefits as well. For 
instance, NHTSA's test dummies are used in a range of applications 
beyond FMVSS compliance testing--such as NCAP testing, standards and 
regulations in other transportation modes, and research. Including the 
dummy design in Part 572 will help provide a suitable, standardized, 
and objective test tool for the safety community.

II. Background

    This document proposes to amend 49 CFR part 572, Anthropomorphic 
Test Devices, to include an advanced test dummy representing a 50th 
percentile adult male, the Test Device for Human Occupant Restraint 
(THOR-50M).\2\ The THOR-50M is a test dummy designed for use in frontal 
crash tests. It has several advanced capabilities and advantages over 
the Hybrid III 50th percentile male test dummy (HIII-50M) that is 
currently specified in Part 572 and used in frontal crash testing under 
FMVSS No. 208, ``Occupant crash protection,'' and the U.S. New Car 
Assessment Program (NCAP).\3\ NHTSA plans to issue a proposal in the 
near future to amend FMVSS No. 208 to specify the THOR-50M as an 
alternative to the HIII-50M for use in frontal crash tests.\4\
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    \2\ NHTSA has registered the term ``THOR'' as a trademark (U.S. 
Registration No. 5,104,395).
    \3\ The HIII-50M is also specified for use in FMVSS No. 202a, 
Head Restraints, in an optional rear impact dynamic test.
    \4\ FMVSS No. 208 THOR-50M Compliance Option (RIN 2127-AM21), 
Spring 2023 Unified Agenda of Regulatory and Deregulatory Actions; 
Department of Transportation, available at https://www.reginfo.gov/public/do/eAgendaViewRule?pubId=202304&RIN=2127-AM21.
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    This document proposes incorporating by reference in Part 572 a 
parts list, design drawings, qualification procedures, and procedures 
for assembly, disassembly, and inspection, to ensure that THOR-50M 
dummies are uniform in design, construction, and response. This section 
provides background on NHTSA's crash test dummies, the development of 
the THOR-50M, and its use in other jurisdictions, among other topics.

Overview of Use of Vehicle Crash Test Dummies

    Anthropomorphic Test Devices (ATDs)--or crash test dummies--are 
complex instruments that serve as human surrogates in vehicle crash 
tests (among other types of tests \5\). Test dummies simulate the 
response of a human occupant in a crash and measure

[[Page 61898]]

the effects of the crash forces on the occupant. They are used to 
estimate the severity of the injuries that would have been experienced 
by a human occupant in a similar crash in the real world. Each type of 
test dummy is designed for use in specific types of crashes (frontal, 
side, etc.), and is instrumented with a wide array of sensors to 
measure the forces that would be relevant in the type of crash for 
which it is designed and to assess the potential for injury. The more 
closely a dummy represents how an actual human would respond, the more 
biofidelic the dummy is considered to be.
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    \5\ NHTSA also uses ATDs in sled tests (which simulate a vehicle 
crash by using a simplified test buck to represent a vehicle), and 
out-of-position air bag tests. ATDs are also used outside the 
vehicle safety context to measure human responses in a variety of 
other areas, such as aviation and aeronautics.
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    NHTSA and the vehicle safety community use crash test dummies in a 
variety of ways. NHTSA uses crash test dummies for vehicle compliance 
testing, safety ratings, and safety research. NHTSA's Federal Motor 
Vehicle Safety Standards establish mandatory minimum safety performance 
requirements for motor vehicles and motor vehicle equipment. Vehicles 
and equipment manufactured for sale in the United States must be 
certified to comply with all applicable FMVSSs. A number of the FMVSSs 
specify crash tests, using specified dummies, that the vehicle must be 
certified as passing.\6\ NHTSA's vehicle safety compliance program 
selects vehicles (and equipment) for compliance testing every year; 
this includes crash testing vehicles to ensure that they comply with 
the performance requirements that are evaluated by means of crash 
tests. NHTSA's NCAP also evaluates vehicle performance in crash tests 
using dummies as part of its 5-Star Safety Ratings. Finally, NHTSA's 
vehicle safety research program uses crash test dummies to evaluate new 
vehicle safety countermeasures and develop new vehicle crash testing 
protocols. Dummies are also used outside of NHTSA by regulatory 
authorities in other countries and regions, for third-party ratings 
(such as Insurance Institute for Highway Safety ratings), and by 
industry and the vehicle safety community to measure performance and 
design safer vehicles.
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    \6\ The FMVSS specify the procedures NHTSA will use in 
compliance testing, including what dummies it will use for testing. 
Part 572 specifies the dummies. While manufacturers must exercise 
reasonable care in certifying that their products meet applicable 
standards, they are not required to follow the compliance test 
procedures set forth in a standard or use the dummy specified in 
Part 572. See, e.g., 38 FR 12934, 12935 (May 17, 1973) 
(``Manufacturers should understand that they are not required to 
test their products in any particular manner, as long as they 
exercise due care that their products will meet the requirements 
when tested by the NHTSA under the procedures specified in the 
standard.'').
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    The dummies NHTSA currently uses in FMVSS compliance testing and in 
NCAP are documented in 49 CFR part 572, Anthropomorphic Test Devices. 
Part 572 sets out detailed design information, including engineering 
drawings and procedures for assembly and inspection. These are all 
intended to describe the dummy with sufficient detail so that it 
produces consistent responses when it is tested under similar 
conditions in repeated tests at the same laboratory (repeatability) or 
between multiple dummies manufactured to the same specification used at 
different test laboratories (reproducibility).

FMVSS No. 208 Frontal Crash Tests Using a 50th Percentile Male Dummy

    FMVSS No. 208, ``Occupant crash protection,'' specifies a variety 
of different requirements using crash test dummies. This includes 
frontal crash tests in which the vehicle is moving and tests that are 
performed with a stationary vehicle and are intended to help ensure 
that air bags do not harm small-stature occupants and children. The 
test dummies used in FMVSS No. 208 were designed to evaluate vehicle 
performance in frontal crashes and are fitted with a variety of 
instruments to measure the forces typically experienced by an occupant 
in a frontal crash.\7\ The 50th percentile male dummy that is currently 
specified for use in FMVSS No. 208 is the Hybrid III-50M.\8\ The HIII-
50M has been specified in FMVSS No. 208 since 1986,\9\ and replaced an 
even earlier dummy, the Hybrid II. FMVSS No. 208 also specifies tests 
using dummies representing a 5th percentile female, a 6-year-old, a 3-
year-old, and an infant.\10\
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    \7\ Other FMVSS specify different types of crash or sled tests 
that use different dummies. For example, FMVSS No. 214, Side Impact 
Protection, specifies two crash tests (simulating a side impact with 
a vehicle and a pole impact). This test uses two different side 
impact dummies.
    \8\ Part 572, Subpart E.
    \9\ 51 FR 26688 (July 25, 1986) (final rule adding HIII-50M). 
The Hybrid III-50M was developed by General Motors and added to Part 
572 and for use in FMVSS No. 208 in response to a petition for 
rulemaking from GM.
    \10\ This reflects a ``bookend'' approach to testing vehicles 
for crashworthiness, in which a range of occupant types, bookended 
by an average male and a small-stature female, is tested. NHTSA is 
currently supporting research to assess the possible benefits of 
developing new crash test dummies, such as a 50th percentile female 
crash test dummy.
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    FMVSS No. 208 specifies two tests (both of which are crash tests) 
using the HIII-50M: a crash test in which the dummy is belted and the 
test vehicle, traveling up to 35 mph, impacts a rigid barrier at a 
ninety-degree angle or perpendicular; \11\ and a crash test in which 
the dummy is unbelted and the test vehicle, traveling 20-25 mph, 
impacts a rigid barrier at an angle ranging from  30 
degrees oblique from perpendicular.\12\ NCAP also evaluates vehicle 
performance in a frontal crash test at 35 mph using a belted HIII-50M 
dummy.
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    \11\ S5.1.1(b)(2), S14.5.1(b).
    \12\ S5.1.2(b), S14.5.2.
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    FMVSS No. 208 regulates vehicle performance in these crash tests by 
specifying injury criteria and associated injury assessment reference 
values (IARVs). Injury criteria and their respective risk functions 
relate instrumentation measurements to a predicted risk of human 
injury. Each IARV is a maximum value or threshold for a specific injury 
criterion that may not be exceeded when the vehicle is tested with the 
specified dummy under the specified test conditions and procedures. For 
example, FMVSS No. 208 specifies a head injury criterion, 
HIC15, with an IARV of 700. Thus, if NHTSA runs a compliance 
frontal crash test and the calculated HIC15 value exceeds 
700, this would be considered an apparent noncompliance. FMVSS No. 208 
specifies the following injury criteria for the HIII-50M: a head injury 
criterion (HIC15); \13\ a thoracic acceleration criterion; 
\14\ a chest deflection criterion; \15\ a criterion based on the 
maximum force transmitted axially through the upper leg (femur); \16\ 
and three neck injury criteria.\17\
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    \13\ S6.2(b).
    \14\ S6.3.
    \15\ S6.4.
    \16\ S6.5.
    \17\ S6.6.
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Development of the THOR ATDs

    NHTSA has continually conducted research into advancements in crash 
safety, including the development of advanced dummies.\18\ The goal of 
this research has been to create ATDs that represent the responses of 
human occupants in modern vehicle environments with advanced restraint 
systems. This research has led to the development of the two Test 
Device for Human Occupant Restraint (THOR) ATDs, designed primarily for 
use in frontal and frontal oblique motor vehicle crash environments. 
There are currently two main implementations of the THOR design, both 
representing seated motor vehicle occupants: one representing a 50th 
percentile male and

[[Page 61899]]

one representing a 5th percentile female.
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    \18\ Haffner, M., Rangarajan, N., Artis, M., Beach, D., 
Eppinger, R., Shams, T., ``Foundations and Elements of the NHTSA 
THOR Alpha ATD Design,'' The 17th International Technical Conference 
for the Enhanced Safety of Vehicles, Paper No. 458, 2001.
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Development of THOR-50M

    The initial design version of the THOR-50M, introduced in 2001, was 
the THOR Alpha.\19\ The THOR Alpha, which integrated some components 
from the earlier prototype demonstrator known as the Trauma Assessment 
Device, introduced some of the features that exist in the current 
version of THOR-50M, including the multi-direction neck, human-like 
ribcage geometry and impact response, multi-point thorax and abdomen 
deflection measurement system, and instrumented lower extremities. 
NHTSA refined the THOR Alpha design and reintroduced it in 2005 as the 
THOR-NT,\20\ which included updates to anthropometry, durability, 
usability, biofidelity, and fit and finish. In 2011, NHTSA, in 
coordination with the SAE International (SAE) THOR Evaluation Task 
Group, introduced a modification package (Mod Kit) intended to enhance 
the biofidelity, repeatability, durability, and usability of the THOR-
NT.\21\ After the introduction of the THOR Mod Kit, an upgrade to the 
Chalmers shoulder assembly that was developed through the European 
Union's THORAX project was integrated into the THOR-50M design.\22\ The 
THOR-50M drawing package was then converted from the traditional 
measurement system to the metric system through soft conversion (where 
any non-metric measurements are mathematically converted to metric 
equivalents without changes to the physical dimensions). All fasteners 
were also replaced with the nearest metric equivalents. NHTSA made this 
integrated drawing package (with incremental improvements and 
corrections) publicly available online in 2015,\23\ 2016,\24\ 2020,\25\ 
and 2023.\26\ The version published in 2023 is referred to as the 2023 
drawing package, which consists of two-dimensional drawings and a Parts 
list; this, together with the Procedures for Assembly, Disassembly, and 
Inspection (PADI), and qualification procedures, is referred to as the 
2023 technical data package. (The version published in 2020 is referred 
to as the ``2018 drawing package'' or the ``2018 technical data 
package.'') The version of THOR that is being proposed is the version 
defined in the 2023 technical data package. In 2019, NHTSA began 
publishing THOR-50M documentation in a new docket titled, ``NHTSA 
Crashworthiness Research--THOR-50M Documentation.'' \27\ In addition to 
the documents that make up the 2018 and 2023 technical data packages, 
the docket folder includes the following: durability report; seating 
procedure; injury criteria; biofidelity report; Oblique Moving 
Deformable Barrier (OMDB) Repeatability and Reproducibility (R&R); and 
Qualification test R&R. This documentation is discussed further in 
Section III.B and in the relevant sections of this preamble.\28\ NHTSA 
has tentatively concluded that the THOR-50M is sufficiently biofidelic, 
exhibits repeatable and reproducible performance, and is sufficiently 
durable. As such, we believe that it would be suitable for use in 
regulatory compliance testing and is therefore suitable for 
incorporation into Part 572. A more detailed discussion of the 
technical data package is provided in Section III.B.
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    \19\ Id.
    \20\ Shams, T., Rangarajan, N., McDonald, J., Wang, Y., Platten, 
G., Spade, C., Pope, P., Haffner, M., ``Development of THOR NT: 
Enhancement of THOR Alpha--the NHTSA Advanced Frontal Dummy,'' The 
19th International Technical Conference for the Enhanced Safety of 
Vehicles, Paper No. 05-0455, 2005.
    \21\ Ridella, S., Parent, D., ``Modifications to Improve the 
Durability, Usability, and Biofidelity of the THOR-NT Dummy,'' The 
22nd International Technical Conference for the Enhanced Safety of 
Vehicles, Paper No. 11-0312, 2011.
    \22\ Lemmen, P., Been, B., Carroll, J., Hynd, D., Davidsson, J., 
Song, E., Lecuyer, E., ``Development of an advanced frontal dummy 
thorax demonstrator,'' Proceedings of the 2012 IRCOBI Conference, 
2012.
    \23\ National Highway Traffic Safety Administration (2015). 
Parts List and Drawings, THOR-M Advanced Frontal Crash Test Dummy, 
September 2015. Regulations.gov Docket ID NHTSA-2015-0119-0005, 
available at: https://www.regulations.gov/document/NHTSA-2015-0119-0005 (NCAP docket).
    \24\ National Highway Traffic Safety Administration (2016). 
Parts List and Drawings, THOR-50M Advanced Frontal Crash Test Dummy, 
August 2016, available at: https://www.nhtsa.gov/es/document/thor-50m-drawing-package-august-2016.pdf.
    \25\ National Highway Traffic Safety Administration. Parts List 
and Drawings, THOR-50M Advanced Frontal Crash Test Dummy, August 
2018. Regulations.gov Docket ID NHTSA-2019-0106-0002, available at: 
https://www.regulations.gov/document/NHTSA-2019-0106-0002.
    \26\ National Highway Traffic Safety Administration. THOR 50th 
Percentile Male with Alternate Shoulders Frontal Crash Test Dummy 
Drawings, External Dimensions, and Mass Properties, THOR-50M 
Advanced Frontal Crash Test Dummy, August 2018. Regulations.gov 
Docket ID NHTSA-2019-0106-0013, available at: https://www.regulations.gov/document/NHTSA-2019-0106-0013.
    \27\ Docket NHTSA-2019-0106.
    \28\ These documents are located in the research docket, Docket 
No. NHTSA-2019-0106. NHTSA is not placing copies of these documents 
in the docket for this rulemaking action in order to avoid potential 
confusion from having identical documents docketed at different 
times in different dockets. Nevertheless, NHTSA intends these to be 
included as part of the rulemaking record for this rulemaking 
action. A memorandum explaining this is also being placed in the 
docket for this rulemaking.
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Development of THOR-05F

    NHTSA understands that the risk of injury in a crash can depend on 
the occupant's physical characteristics (e.g., height, weight, bone 
density) and how they interact with the restraint system and vehicle 
environment. To that end, NHTSA has developed comprehensive research 
plans to address differences in crashworthiness safety testing and 
outcomes, including differences in injury risk. Human body modeling 
research efforts are underway to consider female and male occupants and 
vulnerable road users of various ages, shapes, and sizes. This includes 
continuing and accelerating research efforts to address differences in 
motor vehicle safety based on physical characteristics, including sex, 
and making data-driven decisions supported by the research outcomes. A 
series of efforts is specifically focused on female occupant crash 
safety, spanning field data analysis, tool development, demonstration, 
and application.\29\
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    \29\ See National Highway Traffic Safety Administration (2022). 
NHTSA Female Crash Safety Research Plan, November 2022. 
Regulations.gov Docket ID NHTSA-2022-0091-0002, available at: 
https://www.regulations.gov/document/NHTSA-2022-0091-0002.
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    As part of these efforts, NHTSA has been developing the THOR 5th 
percentile adult female frontal crash test dummy (THOR-05F). The THOR-
05F represents a small adult female and has a seated height of 81.3 cm 
(32.0 in), approximate standing height of 151 cm (59.4 in), and weight 
of 49 kg (108.0 lbs). The THOR-05F has improved measurement 
capabilities over the Hybrid III-5F, which is specified in FMVSS No. 
208 and documented in Part 572. The THOR-05F's instrumentation is 
similar to that of the THOR-50M. Improved designs resulting from the 
development of the THOR-50M related to the head, neck, thorax, and 
lower extremities have also been incorporated into the design of the 
THOR-05F. Currently, NHTSA is evaluating the THOR-05F's biofidelity and 
durability, developing design updates, injury criteria, and 
documentation, and assessing its utility in full-scale crash testing.
    NHTSA anticipates completing the research and testing necessary to 
support a rulemaking for the THOR-05F

[[Page 61900]]

in 2023.\30\ Possible test modes in which THOR-05F may be used include 
FMVSS No. 208 testing and NCAP frontal crash tests. NHTSA has placed 
documentation and research for the THOR-05F in an online docket and 
will continue adding additional research and information to this docket 
as it becomes available.\31\
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    \30\ Part 572 THOR 5th Female Crash Test Dummy (RIN 2127-AM56), 
Spring 2023 Unified Agenda of Regulatory and Deregulatory Actions; 
Department of Transportation, available at https://www.reginfo.gov/public/do/eAgendaViewRule?pubId=202304&RIN=2127-AM56. This 
rulemaking would amend 49 CFR part 572 by adding design and 
performance specifications for a new test dummy known as the THOR-
05F.
    \31\ See Docket No. NHTSA-2019-0107, available at 
regulations.gov.
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Innovative Features of the THOR-50M

    Frontal crashes are the leading cause of injuries and fatalities in 
occupants of motor vehicle crashes on U.S. public roadways. The vehicle 
front is the initial point of impact in a majority of crashes in the 
U.S. In 2021, 15,570 occupants of passenger cars or light trucks died, 
and 1,144,169 were injured, in frontal crashes.\32\ This suggests that 
even though occupant protection systems have improved over the years 
and saved many lives,\33\ improvements to occupant protection in 
frontal crashes still need to be made.
---------------------------------------------------------------------------

    \32\ Data Sources: Fatality Analysis Reporting System (FARS): 
2017-2020 Final File and 2021 Annual Report File (ARF); Report 
Generated: Wednesday, June 28, 2023 (12:48:52 p.m.); VERSION 5.6, 
RELEASED MAY 19, 2023
    \33\ Charles J. Kahane, Lives Saved by Vehicle Safety 
Technologies and Associated Federal Motor Vehicle Safety Standards, 
1960 to 2012--Passenger Cars and LTVs--With Reviews of 26 FMVSS and 
the Effectiveness of Their Associated Safety Technologies in 
Reducing Fatalities, Injuries, and Crashes. 89 DOT HS 812 069 at 89, 
Department of Transportation, National Highway Traffic Safety 
Administration (2015).
---------------------------------------------------------------------------

    The THOR-50M is designed to better evaluate the effectiveness of 
modern vehicle restraint systems and address the types of injuries that 
continue to occur. These improvements include the following:
    Improved biofidelity. Biofidelity is a measure of how well a dummy 
replicates the response of a human. The THOR-50M was designed with 
advanced features that enable it to have improved biofidelity compared 
to the HIII-50M. The dummy's head includes a deformable facial insert 
that emulates human response to impact. The components in the neck 
representing bone and ligament structure are separate from those 
representing muscular structure, improving both kinematic response and 
injury prediction. The thorax simulates the shape and impact response 
of the human rib cage. The spine incorporates flexible joints in the 
thoracic and lumbar spine, allowing dynamic spine flexion as well as 
static adjustment in the neck and lumbar spine to accommodate seating 
in various postures. The upper leg has a compressive element in the 
femur and the lower leg has a compressive element in the tibia and an 
Achilles tendon load path to achieve human-like impact response. The 
biofidelity of the THOR-50M has been assessed in a wide array of both 
component and full-body test conditions for which human response is 
known and was found to be both qualitatively and quantitatively 
congruent with human response corridors.
    Improved instrumentation. The THOR-50M has both improved and 
additional instrumentation compared to the HIII-50M. The thorax 
instrumentation measures the three-dimensional deformation of the rib 
cage at four locations. The abdomen is also designed with a multi-point 
measurement system that monitors three-dimensional deformation of the 
abdomen at two locations. The upper leg includes an acetabulum load 
cell in the pelvis to measure load transfer from the femur to the hip. 
The lower leg has extensive instrumentation to support injury risk 
calculation.
    Improved injury prediction. The biofidelity of the THOR-50M, 
combined with its extensive instrumentation, provides an enhanced 
capability to measure expected human response and predict injury. 
Injury criteria and injury risk functions, which relate instrumentation 
measurements to a predicted risk of human injury, have been developed 
for the head, neck, chest, abdomen, pelvis, upper leg, and lower leg of 
the THOR-50M.\34\ These include injury criteria analogous to those 
currently specified for the HIII-50M in FMVSS No. 208 as well as injury 
criteria that are not currently specified for the HIII-50M in FMVSS No. 
208. We believe this enhanced injury prediction capability will 
translate into restraint system designs that have the potential to 
enhance occupant protection. NHTSA and others, including vehicle 
manufacturers, have already taken advantage of these capabilities in 
the research arena.
---------------------------------------------------------------------------

    \34\ Craig, M., Parent, D., Lee, E., Rudd, R., Takhounts, E., 
Hasija, V. (2020). Injury Criteria for the THOR 50th Male ATD. 
Regulations.gov Docket ID NHTSA-2019-0106-0008, available at: 
https://www.regulations.gov/document/NHTSA-2019-0106-0008.
---------------------------------------------------------------------------

    Improved evaluation of vehicle performance. These enhancements 
allow the THOR-50M to better differentiate the performance of different 
vehicles and restraint systems. The more sophisticated measurement 
capabilities of an advanced ATD are better suited to develop and test 
more sophisticated and highly tunable contemporary restraint systems 
with features such as multi-stage air bags and force-limiting/
pretensioning seat belts. Motor vehicle manufacturers and restraint 
suppliers have already used the THOR-50M to evaluate vehicle 
crashworthiness and develop occupant protection countermeasures. 
Numerous conference and journal articles describing the use of the 
THOR-50M have been published. For example, in a study examining the 
performance of different restraint systems in frontal impact sled tests 
using both the THOR-50M and HIII-50M, the THOR-50M was found to be more 
sensitive to the restraint conditions, as it was able to differentiate 
between both crash severity and restraint performance.\35\ Another 
study investigated a novel air bag system with three inflated chambers 
with a connected sail panel to promote earlier engagement with the 
occupant and prevent lateral motion and head rotation; sled testing 
using the THOR-50M demonstrated a reduction in brain injury risk due to 
head angular velocity, as quantified using the Brain Injury Criterion 
(BrIC).\36\ Other studies have also implemented the THOR-50M to assess 
and develop restraint systems.\37\
---------------------------------------------------------------------------

    \35\ Sunnev[aring]ng, C., Hynd, D., Carroll, J., Dahlgren, M., 
``Comparison of the THORAX Demonstrator and HIII Sensitivity to 
Crash Severity and Occupant Restraint Variation,'' Proceedings of 
the 2014 IRCOBI Conference, Paper No. IRC-14-42, 2014.
    \36\ Hardesty, J. (2021). Next-Generation Passenger Airbag. SAE 
Government-Industry Digital Summit (oral only).
    \37\ See also, e.g., Hu, J., Reed, M. P., Rupp, J. D., Fischer, 
K., Lange, P., & Adler, A. (2017). Optimizing seat belt and airbag 
designs for rear seat occupant protection in frontal crashes (No. 
2017-22-0004). SAE Technical Paper; Eggers, A., Eickhoff, B., 
Dobberstein, J., Zellmer, H., Adolph, T. (2014). Effects of 
Variations in Belt Geometry, Double Pretensioning and Adaptive Load 
Limiting on Advanced Chest Measurements of THOR and Hybrid III. 
Proceedings of the 2014 IRCOBI Conference, Paper No. IRC-14-40; Hu, 
J., Fischer, K., Schroeder, A., Boyle, K., Adler, A., & Reed, M. 
(2019, October). Development of oblique restraint countermeasures 
(Report No. DOT HS 812 814). Washington, DC: National Highway 
Traffic Safety Administration. Available at: https://rosap.ntl.bts.gov/view/dot/44143.
---------------------------------------------------------------------------

Adoption of the THOR-50M in Europe

    In 2013, the European Commission (EC) issued a final report 
detailing the need for a new crash test dummy as a means to implement 
regulatory requirements for new vehicle safety technologies, 
particularly those technologies that reduce thorax injuries in frontal 
crashes.\38\ At the time, the

[[Page 61901]]

THOR-50M was envisioned as the best evaluation tool for this purpose. 
In 2015, United Nations Economic Commission for Europe (UNECE) 
Regulation No. 137 (R137) went into effect. R137 specifies a 50 km/h, 
full-width rigid barrier frontal impact test with driver and passenger 
HIII-50M and HIII-5F dummies respectively. One objective of the 
regulation was to encourage better restraint systems across a wider 
range of collision severities.\39\
---------------------------------------------------------------------------

    \38\ European Commission, Seventh Framework Programme, THORAX 
Project Final Report, Thoracic injury assessment for improved 
vehicle safety, 1/7/2013.
    \39\ Seidl, M., Edwards, M., Barrow, A., Hynd, D., & Broertjes, 
P. (2017). The Expected Impact of UN Regulation No. 137 Tests on 
European Cars and Suggested Test Protocol Modifications to Maximise 
Benefits. In 25th International Technical Conference on the Enhanced 
Safety of Vehicles (ESV).
---------------------------------------------------------------------------

    In 2017, an ECE-funded study found that the R137 condition and 
dummy diversity were not sufficiently different to existing UN 
Regulation No. 94 (R94) to force improvements in restraint systems. R94 
involves a 56 km/h frontal offset test which also prescribes the HIII-
50M in the driver and right front seat. To deliver the expected 
benefits, the 2017 final report recommended implementation of the THOR-
50M in R137 as a replacement for the HIII-50M.\40\ The THOR-50M was 
recognized as being more biofidelic in its representation of thoracic 
response and prediction of thorax injuries, which are the key serious 
and fatal injury types in full-width collisions targeted by R137.
---------------------------------------------------------------------------

    \40\ Seidl M, Hynd D, McCarthy M, Martin P, Hunt R, Mohan S, 
Krishnamurthy V and O'Connell S: TRL Ltd. (2017). In depth cost-
effectiveness analysis of the identified measures and features 
regarding the way forward for EU vehicle safety, Final Report, ISBN 
978-92-79-68704-4, European Commission, 08-31-2017.
---------------------------------------------------------------------------

    In 2018, the EC published a report on the cost-effectiveness and 
the number of future injuries and fatalities that could be prevented at 
a European level for different sets of vehicle safety measures.\41\ 
Several new sets of safety measures were considered for mandatory 
implementation in new vehicles starting from 2022. This included the 
introduction of the THOR-50M into R137. The THOR-50M was considered for 
inclusion in a program titled ``Full-width Frontal Occupant Protection 
with THOR (FFW-THO),'' which would lower injury criteria thresholds to 
encourage implementation of adaptive restraints. It was envisioned that 
the implementation of the THOR-50M would result in an initial cost of 
16 Euros per vehicle, for vehicles that currently comply with UN 
Regulation No. 137 with Hybrid III ATDs but not with THOR-50M ATDs. It 
was estimated that vehicles that comply with FFW-THO would provide a 6% 
increase in effectiveness in protecting against serious injuries 
compared to vehicles that comply with R137 alone.
---------------------------------------------------------------------------

    \41\ Seidl, M., Khatry, R., Carroll, J., Hynd, D., Wallbank, C., 
Kent, J. (2018) Cost-effectiveness analysis of Policy Options for 
the mandatory implementation of different sets of vehicle safety 
measures--Review of the General Safety and Pedestrian Safety 
Regulations, Technical Annex to GSR2 report SI2.733025.
---------------------------------------------------------------------------

    In 2019, the EC presented work priorities to WP.29 \42\ for 2019-
2021 for UNECE activities. An amendment to introduce the THOR-50M into 
R137 was included. The target date for a WP.29 vote was listed as Q4/
2021.\43\ In 2020, Japan and the EC jointly initiated discussions 
within WP.29 to establish a priority for the new task. In preparation 
for an eventual adoption into R137, the E.C. commissioned TRL 
(Transport Research Laboratory, UK) \44\ to conduct a survey of various 
stakeholders on the readiness of the THOR-50M. ATD manufacturers, crash 
test laboratories, and crash safety research laboratories were 
consulted. The results of the survey are contained within Annex 7 of a 
broader report on general safety regulations, published by the E.C. in 
2021.\45\ In the E.C. report, there are a number of recommendations 
based on stakeholder feedback. They include revisions to the dummy 
design and qualification procedures that may be needed prior to 
adopting THOR-50M into M.R. 1 \46\ and R137. Most stakeholders 
recommended the formation of either an Informal Working Group or a 
Technical Evaluation Group under the umbrella of UNECE WP.29 to co-
ordinate this activity. As of May 2023, a WP.29 working group has yet 
to be established and timelines for amendments to R137 and M.R. 1 are 
undetermined. The areas for further investigation identified in Annex 7 
are discussed in this NPRM.
---------------------------------------------------------------------------

    \42\ This was a thrice-annual briefing on the regulatory status 
within the various working parties under WP.29's World Forum for 
Harmonization of Vehicle Regulations, including the status of R137 
under the Working Party for Passive Safety (GRSP).
    \43\ WP.29-177-18, 177th WP.29, 12-15 March 2019, EU Work 
priorities for 2019-2021 for UNECE activities.
    \44\ TRL serves as an independent advisory to the E.C. TRL's 
report was performed under contract with the European Commission 
(E.C.), who sought to update the General Safety Regulation for 
Europe to include new and developing technologies with the aim of 
reducing Europe's annual road fatalities. The report reflects TRL's 
recommendations for consideration by the E.C.
    \45\ General Safety Regulation: Technical study to assess and 
develop performance requirements and test protocols for various 
measures implementing the new General Safety Regulation, for 
accident avoidance and vehicle occupant, pedestrian and cyclist 
protection in case of collisions, Final Report, March 2021, 
Publications Office of the EU (europa.eu)), ISBN 978-92-76-08556-0, 
DOI 10.2873/499942, Catalogue number, ET-04-19-467-EN-N. https://op.europa.eu/en/publication-detail/-/publication/6987b729-a313-11eb-9585-01aa75ed71a1/language-en/format-PDF/source-217672351 (last 
accessed 5/25/2023).
    \46\ Mutual Resolution No. 1 (M.R.1) of the 1958 and the 1998 
Agreements. Concerning the description and performance of test tools 
and devices necessary for the assessment of compliance of wheeled 
vehicles, equipment and parts according to the technical 
prescriptions specified in Regulations and global technical 
regulations, ECE/TRANS/WP.29/1101, 10 January 2013.
---------------------------------------------------------------------------

    Although the ECE has not yet officially adopted the THOR-50M, the 
European New Car Assessment Programme (Euro NCAP) has been rating 
vehicles using the dummy. Euro NCAP has implemented a moving 
progressive deformable barrier (MPDB) frontal impact testing protocol 
with a THOR-50M in the driver's seat.\47\ The THOR-50M used by Euro 
NCAP is specified in Technical Bulletin 026 (TB026) \48\ ``THOR 
Specification and Certification.''TB026 explicitly adopts--with some 
variations--NHTSA's 2018 technical data package (i.e., the 2018 drawing 
package,\49\ qualification procedures,\50\ and PADI \51\). The 
variations to the 2018 technical data package are relatively limited. 
For example, TB026 specifies an onboard (in-dummy) data acquisition 
system and a variation to the adjustable spine to facilitate data 
acquisition system (DAS) installation; minor deviations in the shoulder 
assembly; and the use of the HIII-50M lower legs. These modifications 
are discussed in more detail in the relevant sections of the preamble 
and are summarized in Section IX, Consideration of alternatives. 
NHTSA's understanding is that no regulatory authorities or third-party 
vehicle rating programs other than Euro NCAP currently specify the 
THOR-50M for use in vehicle crash tests.
---------------------------------------------------------------------------

    \47\ European New Car Assessment Programme (2022). MPDB Frontal 
Impact Testing Protocol, Version 1.1.3, available at: https://www.euroncap.com/en/for-engineers/protocols/adult-occupant-protection/.
    \48\ European New Car Assessment Programme (2023). THOR 
Specification and Certification, Version 1.3, available at: https://www.euroncap.com/en/for-engineers/supporting-information/technical-bulletins/.
    \49\ Sec.  1.1.
    \50\ Sec.  2.1.
    \51\ Sec.  3.1.
---------------------------------------------------------------------------

    Motor vehicle and equipment manufacturers' interest in the design 
and operation of the THOR-50M has been heightened since the dummy was 
introduced into Euro NCAP and plans for R137 were announced. 
Discussions are taking place within International Standards 
Organization (ISO) Technical Committee 22 (Road Vehicles), Sub-
Committee 36 (Safety and impact testing), Working Group 5 
(Anthropomorphic test devices) for

[[Page 61902]]

modifications suggested by manufacturers. With no defined European 
entity to maintain configuration control, ISO has enlisted Humanetics 
Innovative Solutions, Inc. (Humanetics) to investigate its change 
recommendations directly. In particular, discussions have taken place 
regarding modifications to the shoulder pad and rib guide. These 
modifications are discussed in the relevant sections of the NPRM.

Need for This Rulemaking

    NHTSA expects a variety of benefits from incorporating the THOR-50M 
in Part 572. The THOR-50M is an advanced dummy with many advantages 
over existing dummies with respect to biofidelity, instrumentation, and 
injury prediction. NHTSA believes that the THOR-50M's enhancements will 
lead to more effective restraint system designs and more informative 
comparisons of the safety of different vehicles. Euro NCAP has adopted 
it, the ECE is considering it for use in R137, and it is likely being 
used by vehicle and restraint manufacturers for testing, research, and 
development. Therefore, we believe vehicle manufacturers would choose 
to certify new vehicles using the THOR-50M if given the option, because 
this would enable manufacturers to streamline testing by using the same 
dummy for research and development and to verify compliance and vehicle 
ratings. NHTSA is therefore also considering a proposal to amend FMVSS 
No. 208 to give vehicle manufacturers the option of selecting the THOR-
50M for use in belted and unbelted crash testing instead of the HIII-
50M.\52\
---------------------------------------------------------------------------

    \52\ FMVSS No. 208 THOR-50M Compliance Option (RIN 2127-AM21), 
Fall 2023 Unified Agenda of Regulatory and Deregulatory Actions; 
Department of Transportation, available at https://www.reginfo.gov/public/do/eAgendaViewRule?pubId=202304&RIN=2127-AM21. This 
rulemaking would propose injury assessment reference values for the 
THOR-50M comparable to the IARVs currently specified for the HIII-
50M.
---------------------------------------------------------------------------

    There would be other benefits as well. For instance, the THOR-50M 
is well-suited for the types of new seating configurations brought on 
by vehicles with Automated Driving Systems (ADS). NHTSA is developing 
an adaptation of the THOR-50M that is better suited for reclined 
postures which may be prevalent among ADS occupants.\53\ NHTSA's test 
dummies are also used in a range of applications beyond FMVSS 
compliance testing--such as NCAP testing, standards and regulations in 
other transportation modes, and research. While the purpose of Part 572 
is to describe the anthropomorphic test devices that are to be used for 
compliance testing of motor vehicles and motor vehicle equipment with 
motor vehicle safety standards,\54\ it also serves as a definition of 
the ATD for other purposes, such as consumer information crash testing, 
standards and regulations in other transportation modes, and research. 
As such, it would be to the benefit of government, academia, and the 
multi-modal transportation industry to include a definition of the 
THOR-50M ATD in Part 572.\55\
---------------------------------------------------------------------------

    \53\ Forman, J., Caudillo-Huerta, A., McMahon, J., Panzer, M., 
Marshall, W., Winter, D., Dyer, M., Lemmen, P. (2021). Modifications 
to the THOR-50M for Improved Usability in Reclined Postures--Update 
and Preliminary Findings. 2021 SAE Government-Industry Digital 
Summit, available at: https://www.nhtsa.gov/node/103691. The 
adaptation to the THOR-50M design for use in reclined seating 
environments is outside of the scope of this Part 572 NPRM.
    \54\ 49 CFR 572.1.
    \55\ For example, American Public Transportation Association 
standard APTA PR-CS-S-018-13 Rev. 1 describes the use of a THOR ATD 
in the testing of fixed workstation tables in passenger rail cars. 
American Public Transportation Association. (2015, October). Fixed 
Workstation Tables in Passenger Rail Cars. PR-CS-S-018-13, Rev. 1. 
Washington, DC, available at: https://www.apta.com/wp-content/uploads/Standards_Documents/APTA-PR-CS-S-018-13-Rev-1.pdf.
---------------------------------------------------------------------------

III. Design, Construction, and Instrumentation

    In this section we discuss the anthropometry, design, construction, 
and instrumentation of the THOR-50M.

A. Anthropometry

    The THOR-50M is a physical model of a 50th percentile male motor 
vehicle occupant. It is intended for use in the development and 
evaluation of vehicle safety countermeasures and vehicle safety 
performance in frontal crash tests. To ensure that the dummy responds 
in a human-like manner in a vehicle crash environment, it is necessary 
that the size and shape of the dummy, referred to as anthropometry, 
provide an accurate representation of a mid-sized male. The 
anthropometry of the THOR-50M is based on a study by the University of 
Michigan Transportation Research Institute that documented the 
anthropometry of a mid-sized (50th percentile in stature and weight) 
male occupant in an automotive seating posture (AMVO 
study).56 57 This study defines an average male as 76.57 kg 
(168.8 lb) in weight with a standing height of 175.1 cm (68.9 in). The 
AMVO study is currently internationally accepted as the standard 
anthropometry for the 50th percentile male ATD. The THOR-50M has a mass 
of 77.37 kg (170.6 lb) and a seated height of 101.8 cm (40.2 in). The 
standing height of the ATD cannot be measured since the pelvis does not 
allow a full standing posture; however, since it was developed using 
the AMVO body segment geometry and seated anthropometry, it is assumed 
that the stature of the THOR-50M is also 175.1 cm.
---------------------------------------------------------------------------

    \56\ Schneider, L.W., Robbins, D.H., Pflug, M.A., Snyder, R. G., 
``Development of Anthropometrically Based Design Specifications for 
an Advanced Adult Anthropomorphic Dummy Family; Volume 1-Procedures, 
Summary Findings and Appendices,'' U.S. Department of 
Transportation, DOT-HS-806-715, 1985.
    \57\ Robbins, D.H., ``Development of Anthropometrically Based 
Design Specifications for an Advanced Adult Anthropomorphic Dummy 
Family; Volume 2-Anthropometric Specifications for mid-Sized Male 
Dummy; Volume 3- Anthropometric Specifications for Small Female and 
Large Male Dummies,'' U.S. Department of Transportation, DOT-HS-806-
716 & 717, 1985.
---------------------------------------------------------------------------

    The THOR-50M is consistent with the AMVO anthropometry. NHTSA 
compared the dimensions of a representative dummy (S/N 9798) with the 
AMVO target dimensions (Table 1).\58\ The AMVO procedure originally 
used to collect measurements from volunteers was adapted to collect the 
same or similar measurements on the THOR-50M.\59\ Most of these 
measurements were taken with the THOR-50M seated on the AMVO bench, 
which has an angled seat and backrest. One adaptation was necessary to 
collect leg measurements on the AMVO bench: the THOR-50M has an 
integrated molded shoe that cannot be separated from its foot, while 
the AMVO data were collected on barefoot volunteers. To remedy this 
situation, the THOR-50M measurements were recorded after removing the 
entire molded shoe assembly and positioning the center of the ankle 
joint at the same location as the AMVO ankle landmark. Another 
adaptation was that four of the measurements were collected with the 
THOR-50M seated on a 90-degree bench, as specified on drawing 472-0000, 
Sheet 4. NHTSA also compared

[[Page 61903]]

the body segment masses specified in the proposed THOR drawing package 
(472-0000, Sheet 5) with the AMVO body segment masses (Table 2), and 
the masses were also consistent.
---------------------------------------------------------------------------

    \58\ A THOR-50M unit is a collection of serialized parts that 
can be swapped out with other dummies, so is not considered a 
``serialized'' dummy. Indeed, many of the subassemblies that were 
part of S/N 9798 when NHTSA took these measurements were 
subsequently swapped out of the dummy. See Section VII.A.
    \59\ These AMVO measurements were collected as an assessment of 
anthropometry; it is understood that there is variation in initial 
position and measurement methodology that prevents the use of such 
measurements as a repeatable dimensional assessment. In practice, a 
simplified set of dimensional requirements are put in place as a 
check for overall part fit, tolerance stack, and to ensure that the 
dummy is assembled correctly. These requirements are specified on 
drawing 472-0000, Sheet 4, and are collected following the 
``Procedures for Measuring External Dimensions'' section of the 
PADI.

            Table 1--THOR-50M Anthropometry Compared to AMVO
------------------------------------------------------------------------
                                            AMVO target
     Dimensions (all measurements in      (Robbins et al   THOR-50M  S/N
              centimeters)                     1983)           9798
------------------------------------------------------------------------
Height of top of head to floor..........           100.3           101.8
Height of shoulder to floor.............            72.1            74.2
H-point to knee joint distance (note 1).            43.2            42.3
Buttock to knee end distance (note 2)...            59.3            62.0
Height of knee from floor...............            45.3            47.0
Head circumference......................            57.1            58.7
Head top-chin distance..................            19.7            22.9
Head breadth............................            15.8            15.3
Chest circumference.....................           101.1            95.5
Chest breadth...........................            34.9            30.9
Chest depth (note 3)....................            22.7            22.4
Abdomen circumference...................            91.3            99.0
Abdomen breadth.........................            32.5            32.5
Abdomen depth (note 2)..................            26.9            29.8
Pelvis breadth..........................            38.5            38.8
Thigh max circumference.................            57.9            56.8
Thigh max breadth.......................            19.4            17.1
Mid thigh circumference.................            50.4            56.0
Mid thigh breadth.......................            15.5            17.8
Calf circumference......................            37.3            37.5
Calf breadth............................            11.0             9.1
Calf depth..............................            11.8            11.9
------------------------------------------------------------------------
\1\ THOR-50M specified on 472-0000, Sh. 4, measurement F (Knee Pivot to
  Hip Pivot) as seated upright on a 90-degree bench.
\2\ THOR-50M and AMVO measured as seated upright on a 90-degree bench.
\3\ THOR-50M specified on 472-0000, Sh. 4, measurement I (Rib #3 depth)
  as seated upright on a 90-degree bench without jacket installed.

         Table 2--THOR-50M Body Segment Masses Compared to AMVO
------------------------------------------------------------------------
                                            AMVO target      THOR-50M
Body segment masses (all measurements in  (Robbins et al   specification
               kilograms)                      1983)             *
------------------------------------------------------------------------
Head....................................           4.137           4.501
                                               ** (4.55)
Neck....................................           0.965           2.363
Thorax..................................          23.763          23.517
Lower Abdomen...........................           2.365           2.664
Pelvis..................................          11.414          15.229
Upper Arm, Left or Right................           1.769           1.701
Lower Arm with Hand, Left or Right......           2.022           2.227
Upper Leg, Left or Right................           8.614           5.618
Lower Legs, Left or Right...............           3.587           3.396
Feet, Left or Right including shoe......       *** 1.551           1.604
                                         -------------------------------
    Total Weight........................          76.562          77.366
------------------------------------------------------------------------
* Listed on Drawing No. 472-0000, Sh. 5.
** Mass reported in Melvin JW, Weber, K. ``Task B Final Report: Review
  of Biomechanical Impact Response and Injury in the Automotive
  Environment,'' U.S. Department of Transportation, DOT-HS-807-042,
  1985. The AMVO target is believed to be too low.
*** This adds the mass of a size 11 Oxford shoe (0.57 kg) specified for
  use in FMVSS No. 208 for the HIII-50M) to the AMVO specification of
  0.981 kg so as to be comparable to the THOR's foot-within-a-molded-
  shoe mass.

B. Technical Data Package

    The construction of the THOR-50M is similar to other ATDs currently 
defined in Part 572, with a metallic frame largely covered in urethane 
and/or vinyl representing flesh; body segments connected by 
translational and rotational joints; and deformable rubber or foam 
elements to prevent hard contact between metallic surfaces and to 
provide human-like impact response. The kinematic and dynamic 
biomechanical performance requirements of the THOR-50M were developed 
based on post-mortem human subject (PMHS) and volunteer response data, 
described in Section IV, Biofidelity.
    The THOR-50M that we are proposing in this NPRM is the version 
defined in the 2023 technical data package (consisting of two-
dimensional engineering drawings and a Parts list; procedures for 
assembly, disassembly, and inspection (PADI); and qualification 
procedures). The 2023 technical data package also includes an addendum 
with the drawings and drawing/parts list for an alternate configuration 
with an in-dummy data acquisition system, as discussed in Section 
III.N, Data Acquisition System. It is anticipated that, upon 
finalization of this proposal,

[[Page 61904]]

the in-dummy DAS drawings will be fully integrated within the relevant 
technical data package components. The technical data package is 
summarized in Table 3. For these documents, the NPRM cites to the 
document location in the research docket. NHTSA is not placing copies 
of these documents in the rulemaking docket, in order to avoid 
potential confusion from having identical documents docketed at 
different times in different dockets. However, NHTSA intends these to 
be included as part of the rulemaking record. A memo explaining this is 
also being included in the rulemaking docket. In addition, as noted in 
the background section, NHTSA began publishing the technical data 
package to its website starting in 2015. The 2023 technical data 
package updates the 2018 technical data package. These updates were 
made to address typographical errors, improve clarity, and add 
alternative design elements. Table 4 summarizes these updates.

                Table 3--THOR-50M Technical Data Package
------------------------------------------------------------------------
                 Title                                 Link
------------------------------------------------------------------------
THOR 50th Percentile Male with           https://www.regulations.gov/
 Alternate Shoulders Frontal Crash Test   document/NHTSA-2019-0106-0013.
 Dummy Drawings, External Dimensions,
 and Mass Properties.
*THOR-50M DAS Integration Kit Drawings,  https://www.regulations.gov/
 April 2023.                              document/NHTSA-2019-0106-0019.
*Parts List, THOR-50M DAS Integration    https://www.regulations.gov/
 Kit, April 2023.                         document/NHTSA-2019-0106-0018.
Parts List, THOR 50th Percentile Male    https://www.regulations.gov/
 Frontal Crash Test Dummy with            document/NHTSA-2019-0106-0015.
 Alternate Shoulders.
THOR 50th Percentile Male (THOR-50M):    https://www.regulations.gov/
 Procedures for Assembly, Disassembly,    document/NHTSA-2019-0106-0017.
 and Inspection (PADI): June 2023.
THOR 50th Percentile Male (THOR-50M)     https://www.regulations.gov/
 Qualification Procedures and             document/NHTSA-2019-0106-0010.
 Requirements, April 2023.
------------------------------------------------------------------------
* The DAS Integration Kit drawings and drawing/parts list would not
  themselves be incorporated by reference into Part 572. It is
  anticipated that, upon finalization of this proposal, these documents
  will be fully integrated within the relevant technical data package
  components.

  Table 4--Summary of Updates Made in the 2023 THOR-50M Technical Data
                                 Package
------------------------------------------------------------------------
    Technical Data Package
           Element                     Revisions in 2023 Version
------------------------------------------------------------------------
Drawing Package..............  Includes drawings for alternate shoulder,
                                removal of notes suggesting that
                                qualification specifications supersede
                                drawing specifications, and changes to
                                correct typographical drawing errors.
                                Complete change log found in ``THOR-50th
                                Percentile Male with Alternate Shoulders
                                (THOR-50M w/ALT. SHOULDERS) Drawing
                                Revisions''.\60\
PADI.........................  Minor typographical changes; complete
                                change log found in Section 20 of ``THOR
                                50th Percentile Male (THOR-50M)
                                Procedures for Assembly, Disassembly,
                                and Inspection (PADI)''.
Qualification Procedures.....  Revised upper leg qualification test
                                mode, adjusted language to be more
                                prescriptive, removed unit conversions,
                                and corrected typographical errors.
                                Complete change log found in Appendix B
                                of ``THOR 50th Percentile Male (THOR-
                                50M) Qualification Procedures and
                                Requirements, April 2023''.
------------------------------------------------------------------------

    Below we briefly discuss several aspects of the technical data 
package in more detail.
---------------------------------------------------------------------------

    \60\ See Table 5.
---------------------------------------------------------------------------

Engineering Drawings and Parts List
    The engineering drawings and parts list specify the configuration 
of the THOR-50M. Included in the drawings are the required dimensions 
and tolerances, material properties, and component or material testing 
requirements and associated specifications. In a few instances, the 
drawings specify quasi-static tests and/or performance requirements for 
individual parts (such as a compression or flexion test for a molded 
part or subassembly); however, passing a specified performance (or 
qualification) test is not an alternate criterion for accepting a part 
that deviates from the drawing specifications.\61\ All instruments are 
specified by corresponding SA572-xxx drawings.\62\ SA drawings are 
included for associated mounts and hardware that are not otherwise 
needed when the dummy is configured with a corresponding structural 
replacement. Brand name call-outs are only used for parts and materials 
that have widespread availability and are used for a wide variety of 
non-ATD applications. It includes materials widely identified by their 
tradenames, such as Teflon, Acetal, Lexan, and Nitinol. Call-outs are 
also used for bonding agents, fasteners, and other items that are also 
widely available for non-ATD applications.
---------------------------------------------------------------------------

    \61\ In the drawings which were part of the August 2018 
technical data package, several notes state that ``qualification 
takes precedence over design.'' These notes were unintentionally 
carried over from earlier drawing versions used during THOR-50M 
development, and have since been removed. These are reflected in the 
proposed 2023 technical data package. In cases where some 
flexibility is allowed in order to meet the qualification 
specification, a ``REF.'' prefix is added to specific dimensions or 
material specifications.
    \62\ This convention is used for all instruments on all Part 572 
dummies. SA572 simply indicates that it is an instrument, and Sxx is 
the next-in-line number assigned by NHTSA to the instrument. Some 
load cells (and part numbers) are used on different Part 572 subpart 
dummies. For THOR, this applies to SA572-S4 (accelerometer) which is 
used on many other dummies.
---------------------------------------------------------------------------

    In some instances, the drawing package permits two different part 
or instrumentation configurations that are both fully specified. For 
example, the head accelerometer mounting plate assembly drawing (472-
1200) calls out three different angular rate sensors (SA572-S56, SA572-
S57, or SA572-S58) which may be desired by the end user depending on 
the implementation of the ATD.\63\ In the sections below on specific 
body regions we discuss the proposed as well as alternate designs and 
instrumentations that are not included in the proposed specifications 
but which we are considering specifying in the final rule and on which 
we are seeking comment. If NHTSA were to use the dummy for FMVSS 
compliance testing, NHTSA could test with any alternative 
configurations at its own discretion. Thus, the IARVs would have

[[Page 61905]]

to be met using a dummy with any permissible configuration. 
Manufacturers are not required to test their products in any particular 
manner, as long as they exercise due care that their products will meet 
the requirements when tested by NHTSA under the procedures specified in 
the standard, including the relevant dummy specified in Part 572.\64\ 
However, a manufacturer would not be able to claim that a vehicle fully 
complies with a standard if it meets the standard's requirements in 
only one of the dummy's configurations, but not the other.
---------------------------------------------------------------------------

    \63\ Similar situations exist with currently federalized ATDs, 
such as the HIII-10C, where either a chest slider pot or an IR-TRACC 
is permissible.
    \64\ See, e.g., 38 FR 12934, 12935 (May 17, 1973) 
(``Manufacturers should understand that they are not required to 
test their products in any particular manner, as long as they 
exercise due care that their products will meet the requirements 
when tested by the NHTSA under the procedures specified in the 
standard.'').
---------------------------------------------------------------------------

    In addition to the engineering drawings that would be incorporated 
by reference, we are also providing supplemental documentation on the 
form and function of the THOR-50M. These reference materials are 
summarized in Table 5. These files would not be incorporated by 
reference in Part 572 and would therefore not be part of the THOR-50M 
specification. Instead, they are intended only for reference purposes 
(e.g., to facilitate fabrication and inspection of parts with intricate 
geometries).

            Table 5--THOR-50M Design Reference Documentation
------------------------------------------------------------------------
                 Title                                 Link
------------------------------------------------------------------------
THOR-50M Drawing Package--2D AutoCAD     https://static.nhtsa.gov/nhtsa/
 Jan 2023.                                downloads/
                                          THOR_50M_Drawing_Package/NPRM/
                                          THOR-
                                          50M%20with%20Alternate%20Shoul
                                          ders%20Jan%202023-
                                          AutoCAD%20DWG%20Files.zip.
THOR-50M Drawing Package--3D Inventor    https://static.nhtsa.gov/nhtsa/
 Format Jan 2023.                         downloads/
                                          THOR_50M_Drawing_Package/NPRM/
                                          THOR-
                                          50M%20with%20Alternate%20Shoul
                                          ders%20Jan%202023-
                                          Inventor%20Files.zip.
THOR-50M Drawing Package--3D STEP        https://static.nhtsa.gov/nhtsa/
 Format Jan 2023.                         downloads/
                                          THOR_50M_Drawing_Package/NPRM/
                                          THOR-
                                          50M%20DAS%20Integration%20Kit-
                                          3D%20STEP%20Files_April%202023
                                          .zip.
THOR 50th Percentile Male with           https://www.regulations.gov/
 Alternate Shoulders Drawing Revisions,   document/NHTSA-2019-0106-0014.
 Jan 2023.
THOR-50M DAS Integration Kit--2D         https://static.nhtsa.gov/nhtsa/
 AutoCAD, April 2023.                     downloads/
                                          THOR_50M_Drawing_Package/NPRM/
                                          THOR-
                                          50M%20DAS%20Integration%20Kit-
                                          AutoCAD%20DWG%20Files_April%20
                                          2023.zip.
THOR-50M DAS Integration Kit--3D STEP    https://static.nhtsa.gov/nhtsa/
 Format, April 2023.                      downloads/
                                          THOR_50M_Drawing_Package/NPRM/
                                          THOR-
                                          50M%20DAS%20Integration%20Kit-
                                          3D%20STEP%20Files_April%202023
                                          .zip.
THOR-50M DAS Integration Kit--Inventor   https://static.nhtsa.gov/nhtsa/
 Format, April 2023.                      downloads/
                                          THOR_50M_Drawing_Package/NPRM/
                                          THOR-
                                          50M%20DAS%20Integration%20Kit-
                                          Inventor%20Files_April%202023.
                                          zip.
------------------------------------------------------------------------

    The THOR-50M used by Euro NCAP is specified in Technical Bulletin 
026, ``THOR Specification and Certification.'' \65\ TB026 explicitly 
adopts--with some deviations--the 2018 drawing package.\66\ These 
deviations in TB026 include specification of an onboard (in-dummy) data 
acquisition system and a variation to the adjustable spine to 
facilitate DAS installation; minor deviations in the shoulder assembly; 
and the use of the HIII-50M lower legs. These modifications are 
discussed in more detail in the relevant sections of the preamble, and 
are summarized in Section IX, Consideration of alternatives. Euro NCAP 
TB026 specifies the 2018 drawing package, while this proposal specifies 
the 2023 drawing package. However, given the differences described in 
Table 4 above, this deviation is likely to be inconsequential. The 
deviations TB026 makes to the 2018 drawing package are not accompanied 
by engineering drawings, which may tend to lessen the dummy's overall 
objectivity. Objectivity is a statutory necessity for ATDs in Part 572. 
While the lack of accompanying drawings for these deviations may be 
adequate for the Euro NCAP rating program, it could lead to a future 
population of THOR-50M units that are sufficiently non-uniform as to 
render them unsuited for FMVSS applications.
---------------------------------------------------------------------------

    \65\ European New Car Assessment Programme (2023). THOR 
Specification and Certification, Version 1.3, available at: https://www.euroncap.com/en/for-engineers/supporting-information/technical-bulletins/.
    \66\ Sec.  1.1.
---------------------------------------------------------------------------

PADI
    The PADI provides step-by-step procedures on how to properly 
assemble the dummy. This includes instructions on part alignment, 
torque settings, wire routings, and other adjustments that are not 
otherwise described in the engineering drawings. The PADI provides 
explicit installation instructions for all instruments. Euro NCAP TB026 
specifies the 2018 PADI,\67\ while this proposal specifies the 2023 
PADI. However, the differences between the 2018 PADI and 2023 PADI are 
primarily corrections to typographic errors, so this deviation is 
likely to be inconsequential. In some instances, the drawing package 
permits two different part or instrumentation configurations that are 
(or will be in the final rule) both fully specified (for example, the 
IR-TRACC and the S-Track for the chest instrumentation). The proposed 
PADI does not currently contain installation instructions for the 
optional parts (e.g. alternate shoulder) or instrumentation (e.g., the 
S-Track). However, where multiple optional configurations are permitted 
and installation differences are non-trivial, NHTSA anticipates 
supplementing the PADI with such instructions in the final rule.
---------------------------------------------------------------------------

    \67\ Sec.  3.1.
---------------------------------------------------------------------------

Qualification Procedures
    The qualification procedures describe a series of impact tests 
performed on a fully assembled dummy or sub-assembly. NHTSA has 
established numeric bounds or acceptance intervals for the ATD 
responses in these tests. The qualification procedures are discussed in 
Section V.

[[Page 61906]]

Summary
    NHTSA believes that the technical data package adequately describes 
and would ensure the uniformity of the dummy. Upon finalization of this 
proposal, a new subpart for the THOR-50M would be added to Part 572, 
and the technical data package documents would be incorporated by 
reference.
    NHTSA seeks comment on whether the dummy is sufficiently specified 
to ensure that dummies are uniform such that they will provide 
repeatable and reproducible measurements. We also seek comment on 
whether it would be useful to end-users of the dummy if NHTSA created a 
list of suppliers used by NHTSA to obtain various parts and 
instrumentation, and/or general specifications or operating 
characteristics of a part (as provided by a manufacturer's 
specification sheet). Such documentation would not be incorporated into 
Part 572 but would be provided as a reference aid for users and could 
be periodically updated by NHTSA.

C. Head and Face

    The head of the THOR-50M is primarily constructed of a cast 
aluminum skull covered in a urethane head skin. It includes two 
features not seen on the HIII-50M: spring towers and a featureless 
face. The spring towers are integral to the response of the head/neck 
system, as they are the mounting location of the cables that represent 
the musculature of the neck (described further in the following 
section). The head is equipped with three uniaxial accelerometers and 
three angular rate sensors at the head center of gravity (CG) to 
measure translational acceleration and angular velocity, respectively. 
The head also includes a biaxial tilt sensor which measures the quasi-
static orientation of the head for pre-test positioning purposes.
    The face is constructed of an open-cell urethane foam sandwiched 
between the head skin and the face load distribution plates. The 
featureless face allows for more repeatable and reproducible 
interactions with potential contact surfaces and meets enhanced 
biomechanical response requirements which have not been implemented on 
any existing ATDs. Additionally, the face can be configured with five 
uniaxial load cells: left and right eye, left and right cheek, and 
chin.\68\
---------------------------------------------------------------------------

    \68\ These load cells have not been used in any tests currently 
available in NHTSA's Vehicle or Biomechanics databases, and are 
typically replaced with structural replacements during testing. 
While the THOR-50M Qualification Procedure does include a face 
impact test which would exercise the face load cells if installed, 
there are currently no qualification specifications on face load 
cell forces.
---------------------------------------------------------------------------

D. Neck

    The neck of the THOR-50M is visibly and functionally different than 
the ATDs currently defined in Part 572. While typical ATD designs use 
only a pin joint between the base of the head and the upper neck load 
cell, the THOR-50M neck is connected to the head via three separate 
load paths: two cables (one anterior and one posterior) and a pin joint 
between the base of the head and the upper neck load cell. These load 
paths are independently instrumented, allowing the isolation of forces 
and moments on the components representing bone and ligament from the 
components representing muscles. This is expected to allow for improved 
injury prediction for the cervical spine because the abbreviated injury 
scale (AIS) 2+ injuries \69\ to the cervical spine in motor vehicle 
crashes are most commonly fractures, so the ability to measure forces 
and moments acting on the bones and ligaments separately from the 
forces acting through the musculature allows a more accurate prediction 
of these fractures.\70\
---------------------------------------------------------------------------

    \69\ The Abbreviated Injury Scale (AIS) 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).
    \70\ Craig, M., Parent, D., Lee, E., Rudd, R., Takhounts, E., 
Hasija, V. (2020). Injury Criteria for the THOR 50th Male ATD. 
Docket ID NHTSA-2019-0106-0008, available at: https://www.regulations.gov/document/NHTSA-2019-0106-0008.
---------------------------------------------------------------------------

    The biomechanical basis of the THOR-50M neck design is well-
established.71 72 The construction of the THOR-50M neck 
allows the head to initially rotate relatively freely in the fore and 
aft directions. This allows the head/neck assembly to demonstrate the 
phenomenon known as head lag demonstrated by human volunteers in 
restrained frontal loading conditions, where the rotation of the head 
is delayed relative to the rotation of the neck.\73\ This phenomenon 
results from the head initially translating forward with respect to the 
base of the neck, which is attached to the restrained torso. The change 
in angle of the head initially lags the change in angle of the line 
between the head and the neck but catches up by the time of peak 
excursion.
---------------------------------------------------------------------------

    \71\ White RP., Zhoa Y., Rangarajan N., Haffner M., Eppinger R., 
Kleinberger M., ``Development of an Instrumented Biofidelic Neck for 
the NHTSA Advanced Frontal Test Dummy,'' The 15th International 
Technical Conference on the Enhanced Safety of Vehicles, Paper No. 
96-210-W-19, 1996.
    \72\ Hoofman, M., van Ratingen, M., and Wismans, J., 
``Evaluation of the Dynamic and Kinematic Performance of the THOR 
Dummy: Neck Performance,'' Proceeding of the International 
Conference on the Biomechanics of Injury (IRCOBI) Conference, pp. 
497-512, 1998.
    \73\ Thunnissen, J., Wismans, J., Ewing, C.L., Thomas, D.J. 
(1995) Human Volunteer Head-Neck Response in Frontal Flexion: A New 
Analysis. 39th Stapp Car Crash Conference, SAE Paper # 952721.
---------------------------------------------------------------------------

    The instrumentation in the neck assembly includes spring load cells 
which measure the compression at the anterior and posterior spring 
locations, six-axis load cells at the top and base of the neck to 
measure the forces and moments developed at these locations, and a 
rotary potentiometer at the occipital condyle pin to measure the 
relative rotation between the head and top of the neck. Due to the 
multiple load paths of the neck, comparing THOR-50M neck forces and 
moments to traditional single-load-path ATD designs is not 
straightforward; the THOR-50M instrumentation would require post-
processing \74\ to represent the total neck forces and moments in order 
to compare to the upper neck load cell measurements of a HIII-50M ATD. 
However, as described in the THOR-50M Injury Criteria Report,\75\ post-
processing of the neck for calculation of neck injury risk is not 
necessary.
---------------------------------------------------------------------------

    \74\ GESAC, Inc (2005). Users Manual: THOR Instrumentation Data 
Processing Program, Version 2.3; Appendix C: Procedure for 
Calculating Head Loads at the Occipital Condyle from Neck Load Cell 
Measurements. National Highway Traffic Safety Administration. 
Available at: https://one.nhtsa.gov/DOT/NHTSA/NVS/Biomechanics%20&%20Trauma/THOR-NT%20Advanced%20Crash%20Test%20Dummy/THORTEST.zip.
    \75\ Craig, M., Parent, D., Lee, E., Rudd, R., Takhounts, E., 
Hasija, V. (2020). Injury Criteria for the THOR 50th Male ATD. 
Docket ID NHTSA-2019-0106-0008, available at: https://www.regulations.gov/document/NHTSA-2019-0106-0008.
---------------------------------------------------------------------------

E. Chest

    Throughout the development of the THOR-50M ATD, specific attention 
was given to the human-like response and injury prediction capability 
of the chest. Below we discuss the design and instrumentation of the 
THOR-50M chest.
1. Design
    The THOR-50M's rib cage geometry is more realistic than the HIII-
50M because the individual ribs are angled downward to better match the 
human rib orientation.\76\ Biomechanical response requirements were 
selected to ensure human-like behavior in response to central chest 
impacts, oblique chest impacts, and steering rim impacts to the

[[Page 61907]]

rib cage and upper abdomen.\77\ Better chest anthropometry means that 
the dummy's interaction with the restraint system is more 
representative of the interaction a human would experience.
---------------------------------------------------------------------------

    \76\ Kent, R., Shaw, C.G., Lessley, D.J., Crandall, J.R. and 
Svensson, M.Y, ``Comparison of Belted Hybrid III, THOR, and Cadaver 
Thoracic Responses in Oblique Frontal and Full Frontal Sled Tests,'' 
Proc. SAE 2003 World Congress. Paper No. 2003-01-0160, 2003.
    \77\ National Highway Traffic Safety Administration, 
``Biomechanical Response Requirements of the THOR NHTSA Advanced 
Frontal Dummy, Revision 2005.1,'' Report No: GESAC-05-03, U.S. 
Department of Transportation, Washington, DC, March 2005. [http://www.nhtsa.gov/DOT/NHTSA/NVS/Biomechanics%20&%20Trauma/THOR-NT%20Advanced%20Crash%20Test%20Dummy/thorbio05_1.pdf.
---------------------------------------------------------------------------

    The design of the THOR-50M includes a part known as a rib guide 
(472-3310) which is intended to prevent excessive downward motion of 
the anterior thorax during an impact. The rib guide is attached to the 
shoulder, and when there is downward motion of the ribs, the bottom of 
the rib damping material on rib #1 (the superior-most rib in the torso, 
472-3310) can contact the top of the rib guide. Over time, this can 
result in an indent in the rib damping material. This indent has been 
observed on NHTSA-owned THOR-50M ATDs, but it has not been a concern as 
this is a sign of the rib guide performing its intended function. While 
this indent is not included on the drawing package, it is understood 
that an indent is acceptable as long as the qualification 
specifications (specifically, those of the upper thorax and lower 
thorax) are met, and it is not so deep that it allows metal-to-metal 
contact between the rib guide and the steel of the rib.
    While Euro NCAP TB026 adopts the chest specified in the 2018 
drawing package without any modifications, NHTSA is aware of two 
potential changes that have been discussed. Both of these changes 
appear to be intended to help ensure that the dummy is able to meet the 
upper thorax qualification response requirements. (The TB026 upper 
thorax qualification response requirements differ in a few ways from 
the proposed qualification requirements. This is discussed in more 
detail in Section V, Qualification Tests.)
    The first change that has been discussed is a shorter rib guide. 
Humanetics Innovative Solutions, Inc. (Humanetics) reported to ISO WG5 
(in June 2020) that while the indent on the damping material has been a 
known issue since the THOR-NT, it has led to concerns because it leads 
to issues meeting the Euro NCAP upper thorax qualification response 
requirements (specifically, the Z-axis upper rib deflection 
requirement) on a consistent basis. Humanetics has therefore suggested 
the use of a new, shorter rib guide which would allow more Z-axis 
deflection--primarily in the upper thorax qualification test, but 
presumably in other impact scenarios as well.
    The second change is an additional rib performance specification. 
NHTSA is aware of a presentation made by the Japanese Automobile 
Manufacturers Association (in June 2020) to ISO WG5 describing an 
additional rib performance specification (i.e., that would be specified 
in the drawing package) geared towards more consistently meeting the 
TB026 upper thorax qualification response requirements. The 
presentation included a procedure for an individual rib test using the 
same apparatus as the rib drop test for the ES-2re 50th percentile 
adult male side impact test dummy.\78\ It noted data showing that the 
stiffness of the individual rib in the drop test was correlated with 
the thoracic impact response in the upper thorax qualification test 
condition.
---------------------------------------------------------------------------

    \78\ 49 CFR 572.185(b) Individual rib drop test.
---------------------------------------------------------------------------

    NHTSA has tentatively decided not to implement either change. 
NHTSA's qualification testing of the dummy did not reveal any issues 
with meeting the proposed upper thorax qualification requirements, so 
we do not believe such changes are necessary. Moreover, before 
implementing the rib guide modification, it could be necessary to 
evaluate whether it would influence the dummy's response in biofidelity 
or thorax injury criteria test conditions. We do note, however, that 
the additional rib performance specification could be a useful way for 
ATD manufacturers to ensure that the fabricated ribs will result in an 
upper thorax qualification response consistent with upper thorax 
qualification specifications.
    We seek comment on these issues. In particular, NHTSA requests 
comment from THOR-50M users who have evaluated alternative rib guide 
designs and have data to support equivalence of durability, 
repeatability and reproducibility, and equivalence of response in 
qualification, biofidelity, injury criteria, and vehicle crash test 
conditions.
2. Instrumentation
    The THOR-50M is capable of measuring detailed information about how 
the chest responds in a crash. While the HIII-50M can measure chest 
deflection at only a single point (the sternum), the THOR-50M measures 
chest deflections at four points. This is useful because thoracic 
trauma imparted to restrained occupants does not always occur at the 
same location on the rib cage for all occupants in all frontal 
crashes.\79\ Measuring deflection from multiple locations has been 
found to improve injury prediction,\80\ and can improve the assessment 
of thoracic loading in a vehicle environment with advanced occupant 
restraint technologies.\81\ While the HIII-50M measures the one-
dimensional deflection at a single point, the THOR-50M can measure the 
three-dimensional position time-history for four points on the anterior 
rib cage relative to the local spine segment of rib origination, with 
two points on the upper chest, and two points on the lower chest. 
Between the upper and lower thorax instrumentation attachment points is 
a flexible joint (the Upper Thoracic Spine Flex Joint), so the 
reference coordinate system for the upper and lower thorax 3D motion 
measurements can change dynamically during a loading event. This 
instrumentation, coupled with its thoracic biofidelity,\82\ provides 
the THOR-50M ATD with the ability to better predict thoracic injuries 
and to potentially drive more appropriate restraint system 
countermeasures.\83\
---------------------------------------------------------------------------

    \79\ Morgan, R.M., Eppinger, R.H., Haffner, M.P., Yoganandan, 
N., Pintar, F.A., Sances, A., Crandall, J.R., Pilkey, W.D., Klopp, 
G.S., Kallieris, D., Miltner, E., Mattern, R., Kuppa, S.M., and 
Sharpless, C.L., ``Thoracic Trauma Assessment Formulations for 
Restrained Drivers in Simulated Frontal Impacts,'' Proc. 38th Stapp 
Car Crash Conference, pp. 15-34. Society of Automotive Engineers, 
Warrendale, PA., 1994.
    \80\ Kuppa, S., Eppinger, R., ``Development of an Improved 
Thoracic Injury Criterion,'' Proceedings of the 42nd Stapp Car Crash 
Conference, SAE No. 983153, 1998 (data set consisting of 71 human 
subjects in various restraint systems and crash severities).
    \81\ Yoganandan, N., Pintar, F., Rinaldi, J., ``Evaluation of 
the RibEye Deflection Measurement System in the 50th Percentile 
Hybrid III Dummy.'' National Highway Traffic Safety Administration, 
DOT HS 811 102, March 2009.
    \82\ Parent, D., Craig, M., Ridella, S., McFadden, J., 
``Thoracic Biofidelity Assessment of the THOR Mod Kit ATD,'' The 
23rd Enhanced Safety of Vehicles Conference, Paper No. 13-0327, 
2013.
    \83\ In addition to the deflection measurement system, the THOR-
50M can also be instrumented with a uniaxial sternum accelerometer, 
triaxial accelerometers installed along the spine at the level of 
T1, T6, and T12, and a five-axis (three forces, two moments) load 
cell installed between the lumbar spine pitch change mechanism and 
the lumbar spine flex joint at the approximate anatomical level of 
T12. Clavicle loads cells can also be installed, but are not 
included in the THOR-50M described in the 2023 drawing package.
---------------------------------------------------------------------------

    NHTSA is proposing to specify two deflection measurement devices, 
either of which NHTSA could choose, at its option, for use in the THOR-
50M: the IR-TRACC and the S-Track.
IR-TRACC
    The 2023 drawing package specifies a specific deflection 
measurement device, the Infrared Telescoping Rod for Assessment of 
Chest Compression (IR-

[[Page 61908]]

TRACC).\84\ The IR-TRACC improved on the previous deflection 
measurement systems (CRUX--Compact Rotary Unit; DGSP--Double Gimbaled 
String Potentiometer) in many ways. The 2023 drawing package specifies 
six IR-TRACCs: four in the thorax and two in the abdomen.\85\ Each IR-
TRACC measures the absolute point-to-point distance along its length; 
this is used in the calculation of thorax and abdomen compression. The 
IR-TRACC is attached to two rotational potentiometers; this enables 
measurement of the three-dimensional position of the anterior 
attachment point at the rib or front of the abdomen relative to the 
attachment point at the spine.
---------------------------------------------------------------------------

    \84\ Rouhana, S.W., Elhagediab, A.M., Chapp, J.J. ``A high-speed 
sensor for measuring chest deflection in crash test dummies.'' 
Proceedings: International Technical Conference on the Enhanced 
Safety of Vehicles. Vol. 1998, Paper No. 98-S9-O-15. National 
Highway Traffic Safety Administration, 1998.
    \85\ See SA572-S117 and SA572-S121.
---------------------------------------------------------------------------

    While NHTSA has generally been satisfied with the performance of 
the IR-TRACC, the experience of NHTSA and other users with IR-TRACC-
equipped THOR-50Ms has revealed a few potential issues. Vehicle 
manufacturers have raised several concerns about the performance and 
durability of the IR-TRACC, such as having to frequently repair or 
replace IR-TRACCs, and problems with the abdomen IR-TRACCs.\86\ And 
during NHTSA-sponsored testing (particularly in the frontal oblique 
crash test mode), NHTSA observed abrupt decreases in the IR-TRACC 
voltage time-history.\87\ We believe this is noise (and not a signal) 
because it occurs in all IR-TRACC voltage channels of a single ATD at 
the same points in time. As explained later in this document (Section 
VII.B.2) and in Appendix F to the preamble,\88\ NHTSA testing has shown 
that once the IR-TRACC voltage signal is linearized, scaled, filtered, 
and converted to three-dimensional deflection, this noise is no longer 
evident. Nonetheless, this presents a risk of perceived or actual 
inaccuracies in thoracic and abdominal injury prediction during crash 
tests.
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    \86\ Alliance of Automobile Manufacturers, Inc. (2016). 
Technical Considerations Concerning NHTSA's Proposal to Rework the 
Agency's New Car Assessment Program (NCAP). Regulations.gov Docket 
ID NHTSA-2015-0119-0313, available at: https://www.regulations.gov/contentStreamer?documentId=NHTSA-2015-0119-0313&attachmentNumber=5&contentType=pdf.
    \87\ See Figure 1 in Hagedorn, A., Murach, M., Millis, W., 
McFadden, J., Parent, D., (2019). Comparison of the THOR-50M IR-
TRACC Measurement Device to an Alternative S-Track Measurement 
Device. Proceedings of the Forty-Seventh International Workshop on 
Human Subjects for Biomechanical Research.
    \88\ NHTSA is placing a separate document, ``Supplemental 
Technical Appendices to Preamble,'' in the docket for this 
rulemaking.
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S-Track
    In 2016 NHTSA issued a request for proposals for commercially-
available devices capable of measuring the same or greater deflection 
range (roughly 90 millimeters of deflection for the thorax and 120 
millimeters of deflection for the abdomen) within the same packaging 
space as the existing IR-TRACC devices.\89\ Only one device--the S-
Track--was identified. The S-Track, which is patented,\90\ is produced 
by ATD-LabTech GmbH. (In 2022, Humanetics acquired ATD-LabTech.) 
Subsequent to the request for proposal, NHTSA also became aware of two 
additional deflection measurement devices: the KIR-TRACC, sold by 
Kistler Group, and the Spiral Track, sold by JASTI. NHTSA does not know 
whether these devices are congruent with the current THOR-50M parts and 
SA-drawings that describe the configuration and installation of IR-
TRACCs. Because NHTSA became aware of these devices late in the 
development process (and neither was identified in NHTSA's request for 
proposals), they have not been considered for inclusion in the 
proposal, although NHTSA is considering evaluating whether they would 
be suitable instrumentation for the THOR-50M. Euro NCAP allows for 
installation of the IR-TRACC, the S-Track, and the KIR-TRACC.\91\
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    \89\ National Highway Traffic Safety Administration (2016). IR-
TRACC Direct Replacement Sensor. Solicitation Number DTNH2216Q00014, 
available at https://sam.gov/opp/d505f6119f9a31bcdfa36607ed669e6b/view.
    \90\ Pheifer, G. (2020). U.S. Patent No. 10,713,974. Washington, 
DC: U.S. Patent and Trademark Office.
    \91\ European New Car Assessment Program (2022). Euro NCAP 
Supplier List, Appendices I & II, October 2022, TB 029, available 
at: https://www.euroncap.com/en/for-engineers/supporting-information/technical-bulletins/https://www.euroncap.com/en/for-engineers/protocols/adult-occupant-protection/.
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    The S-Track is similar to the IR-TRACC in that it is in-dummy 
instrumentation that attaches to the same points in the dummy as the 
IR-TRACC. Both measure linear displacement, and when coupled with the 
gimballed potentiometers, their signals can be post-processed to 
calculate three-dimensional motion. It differs in that the S-Track uses 
a mechanical scissor mechanism coupled to a linear potentiometer to 
measure linear motion along its axis, while the IR-TRACC uses a 
measurement of light transmittance, which requires a linearization 
calculation to estimate linear motion.
    NHTSA has conducted a range of testing to evaluate the performance 
and equivalence of the S-Track. The testing, which included a partial 
qualification test series and sled tests, is briefly summarized 
below.\92\ A more detailed discussion of this material is available in 
a previously published paper (except, as noted below, the second set of 
sled tests, for which a report is forthcoming).\93\
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    \92\ This evaluation of alternate thorax and abdomen 
instrumentation only considered replacement of the displacement 
transducer component of the 3D IR-TRACC measurement system. Though 
it was not available at the time of purchase, a double gimbal kit to 
allow 3D measurement is now available from the S-Track manufacturer. 
ATD-Labtech GmbH (2017). 3D Adaption THOR-50th upper Thorax left 
20_303. Available at: https://www.atd-labtech.com/files/atd/uploads/produkte/s-track/produkte/4%20TH-3D-Adapter-Upper-Thorax-left/data_sheet-3D-Adaption_Thor-50th_upper_Thorax_left%20Rev%2001.PDF. 
To evaluate whether the S-Track 3D adaption kit would result in 
equivalent measurement capabilities as the 3D IR-TRACC measurement 
system, the testing described here would be repeated, starting with 
the 3D static measurement assessment.
    \93\ Hagedorn, A., Murach, M., Millis, W., McFadden, J., Parent, 
D., (2019). Comparison of the THOR-50M IR-TRACC Measurement Device 
to an Alternative S-Track Measurement Device. Proceedings of the 
Forty-Seventh International Workshop on Human Subjects for 
Biomechanical Research. Available at: https://www-nrd.nhtsa.dot.gov/pdf/bio/proceedings/2019/Hagdeorn_S-Track_Biomechanics%20Workshop%202019_FINAL.pdf.
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     The range and linearity of the S-Track and IR-TRACC 
sensors are comparable. The range of measurement of the S-Track is 
consistent with or larger than the range of measurement of the IR-
TRACC, and all sensors were within the manufacturer's specification for 
the maximum allowable linear error as a percentage of full scale. This 
specification (0.5%) is tighter compared to the corresponding IR-TRACC 
specification (2%), though only one of the IR-TRACCs (right abdomen) 
showed a linearity error greater than 0.5%.
     Calibration and 3D static measurement assessments 
demonstrated similar or better accuracy compared to the IR-TRACC in the 
double-gimbal configuration for the upper left thorax, lower left 
thorax, and left abdomen. In the upper and lower thorax configurations, 
the S-Track showed less error than the IR-TRACC, and in the abdomen 
configuration, showed errors similar to the IR-TRACC.
     The form, fit, and function is comparable to the IR-TRACC. 
A full set of six S-Tracks was installed in a THOR-50M ATD. It did not 
present any connectivity or interference issues and appeared to be a 
plug-and-play replacement to the IR-TRACCs. One possible durability 
issue was identified

[[Page 61909]]

(damage to the cable at the base of the S-Track). This issue is 
mitigated if cable routing documentation is followed or the S-Track-
specific double-gimbal assembly is used.
     The S-Track performed equivalently in qualification tests. 
NHTSA carried out the qualification tests for the body regions expected 
to be sensitive to a difference in thorax and abdomen instrumentation 
(upper thorax, lower thorax, and abdomen) on a THOR-50M in two 
different configurations: a baseline configuration with IR-TRACCs in 
all locations, and an alternate configuration with S-Tracks in all 
locations. Both configurations met the qualification targets for all of 
the test modes specified for those body regions, which demonstrates 
that the difference in measured deflections between the S-Track and IR-
TRACC were well within expected test-to-test variation. In addition, 
the deflection time-history was qualitatively similar to the IR-TRACC.
     The S-Track performed equivalently to the IR-TRACC in most 
respects in a series of sled tests. NHTSA conducted sled tests in 
several conditions with the THOR-50M in two configurations: one with 
the IR-TRACC in all locations, and one with the S-Track in all 
locations:
    [cir] The first series used a reinforced buck representative of the 
front half of a mid-sized passenger vehicle (including seat belt, 
frontal air bag, and side curtain air bag) and simulated a near-side 
frontal oblique (20 degrees) crash. The crash pulse was based on a 
frontal oblique crash test of the same vehicle. The S-Track proved to 
be durable and did not demonstrate the same noise artifacts as the IR-
TRACC. The S-Tracks in the thorax showed similar measurements as the 
IR-TRACCs, particularly in the upper right thorax, the closest 
measurement location to the shoulder belt. There were some potential 
differences between the abdomen measurements, but abdominal deflection 
is not currently included as an injury criterion in FMVSS No. 208 and 
is not currently included in the rating calculation for frontal 
NCAP.\94\
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    \94\ Additional evaluation would be desirable in cases where 
abdominal deflection is a critical measurement, such as a rear seat 
environment where submarining may be more likely to occur.
---------------------------------------------------------------------------

    [cir] The second series of sled tests were conducted in the Gold 
Standard 1 (40 km/h, 12g peak pulse, standard lap and shoulder belt) 
and Gold Standard 2 (30km/h, 9g peak pulse, 3kN load limited shoulder 
belt) test conditions, which were used both in biofidelity assessment 
and in the development of thoracic injury criteria.\95\ The goal of 
this testing was to determine if any differences occurred between the 
IR-TRACC and S-Track measurement devices, and if so, whether the 
magnitude of these differences would affect the biofidelity and injury 
criteria development analyses. NHTSA is preparing a report on this 
second series of sled tests, which will be placed in the research 
docket when it is complete.
---------------------------------------------------------------------------

    \95\ The Gold Standard 1 test uses a flat rigid seat, standard 
lap and shoulder belts, knees restrained, and right front passenger 
restraint geometry. The Gold Standard 2 test uses a flat rigid seat, 
a force-limited shoulder belt and standard lap belt, knees 
restrained, and right front passenger restraint geometry.
---------------------------------------------------------------------------

    Based on this testing and analysis, NHTSA believes that the S-Track 
is equivalent to the IR-TRACC (with the potential exception of the 
abdomen deflection in a sled test environment).
Proposal
    NHTSA proposes to specify both the IR-TRACC and the S-track as 
permissible instrumentation for the THOR-50M. A THOR-50M configured 
with all IR-TRACCs or all S-tracks would conform to Part 572 and NHTSA 
could perform compliance testing with either device installed in the 
THOR-50M. The dummy has not been tested in a mixed configuration, with 
both devices installed (e.g., IR-TRACCS in the chest and S-Tracks the 
abdomen, or with one IR-TRACC and three S-Tracks in the chest). The 
overall effects of such configurations are unknown. NHTSA seeks comment 
on whether the final specifications should allow such configurations. 
The IR-TRACC is specified in the 2023 drawing package (in SA572-S117 
and SA572-S121). NHTSA has not yet published engineering drawings and 
parts packages to specify how the S-Track is installed in the dummy, 
but intends to integrate such documentation into the associated 
technical data package components upon finalization of this proposal. 
NHTSA seeks comment on this proposal.

F. Shoulder

    The THOR-50M shoulder was developed to allow a human-like range of 
motion and includes a clavicle linkage intended to better represent the 
human shoulder interaction with shoulder belt restraints.\96\ Clavicle 
load cells that can be installed in the proximal and distal ends of the 
clavicles are commercially available, but these load cells are not 
currently defined in the drawing package and NHTSA has not evaluated 
them.
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    \96\ T[ouml]rnvall, F.V., Holmqvist, K., Davidsson, J., 
Svensson, M.Y., H[aring]land, Y., [Ouml]hrn, H., ``A New THOR 
Shoulder Design: A Comparison with Volunteers, the Hybrid III, and 
THOR NT,'' Traffic Injury Prevention, 8:2, 205-215, 2007.
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    Below we discuss shoulder components for which NHTSA is proposing 
alternative permissible specifications (the alternate shoulder) or for 
which design modifications have been developed by external THOR-50M 
users but which NHTSA has tentatively decided not to incorporate in the 
drawing package (shoulder slip and coracoid process).
1. Alternate Shoulder Specification
    Portions of the shoulder assembly specified in the 2018 drawing 
package (referred to as the SD-3 shoulder) are covered by a patent 
issued to Humanetics. However, for the reasons discussed in more detail 
in Section VIII, NHTSA has generally avoided specifying in Part 572 
patented components or copyrighted designs without either securing 
agreement from the rights-holder for the free use of the item or to 
license it on reasonable terms or developing an alternative 
unencumbered by any rights claims. NHTSA has therefore designed, built, 
and tested an alternative design for a part of the shoulder assembly 
referred to as the shoulder pivot assembly that is not subject to any 
intellectual property claims. Accordingly, the proposed drawing package 
(the 2023 drawing package) includes specifications for the SD-3 
shoulder pivot assembly as well as the alternate shoulder pivot 
assembly, so that either may be used. We explain this in more detail 
below.
SD-3 Shoulder
    The SD-3 shoulder is notably different from the shoulder specified 
for the THOR-NT. The THOR-NT design includes a clavicle linkage 
attached by ball joints at the sternum and acromion, a linkage between 
the acromion and the scapula to which the upper arm attaches, and a 
linkage representing the scapula that attaches to the acromion linkage 
and the spine with unconstrained revolute joints. While there were some 
benefits of the THOR-NT design compared to existing ATDs at the time, 
the range of motion of the THOR-NT shoulder was found to be lacking 
compared to the human shoulder.\97\
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    \97\ Shaw, G., Parent, D., Purtsezov, S., Lessley, D., Crandall, 
J., Tornvall, F., ``Torso Deformation in Frontal Sled Tests: 
Comparison Between THOR-NT, THOR-NT with the Chalmers SD-1 Shoulder, 
and PMHS,'' Proceedings of the International IRCOBI Conference, 
2010.
---------------------------------------------------------------------------

    An improved shoulder design was independently initiated by the 
Chalmers University of Technology (Chalmers), in

[[Page 61910]]

a project sponsored by Volvo and Autoliv, that sought to improve the 
prediction of occupant response in offset and oblique frontal crashes. 
Several prototype shoulder assemblies were constructed and evaluated, 
the most promising being labeled the Shoulder Design 1 (SD-1).\98\ The 
SD-1 shoulder design includes a clavicle linkage with human-like 
geometry, connected by cardan joints to the sternum and acromion; a 
linkage representing the scapula that includes attachment to the upper 
arm; and a two-part linkage connecting the scapula to the spine which 
allows both upward and anterior motion of the shoulder assembly. The 
anterior rotation of the scapula linkage about a vertical shaft is 
governed by a coil spring within an assembly mounted to the spine box. 
Several rotation stops are installed throughout the assembly to prevent 
metal-to-metal contact at the extents of the range-of-motion.
---------------------------------------------------------------------------

    \98\ T[ouml]rnvall et al. (2007), 205-215.
---------------------------------------------------------------------------

    After evaluation of the SD-1 in dynamic sled testing in comparison 
to the standard THOR-NT shoulder and to PMHS,\99\ several improvements 
were proposed, including durability improvements to the humerus joint, 
decreasing the range of motion in the anterior and superior directions, 
and increasing the range of motion in the posterior and medial 
directions. The improved design, labelled as the SD-2 shoulder, was 
fabricated by GESAC to Chalmers' specifications, installed on a THOR-
50M ATD, and evaluated in sled tests in the Gold Standard 1 and Gold 
Standard 2 conditions at the University of Virginia.\100\ Several 
additional durability and usability concerns were raised upon post-test 
inspection, including deformation of the joint between the clavicle and 
the acromion and hard contact to the humerus joint.
---------------------------------------------------------------------------

    \99\ Shaw et al (2010).
    \100\ Crandall, J. (2013). ATD Thoracic Response: Effect of 
Shoulder Configuration on Thoracic Deflection. NHTSA Biomechanics 
Database, Report b11017R001, available at: https://www-nrd.nhtsa.dot.gov/database/MEDIA/GetMedia.aspx?tstno=11017&index=1&database=B&type=R.
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    Subsequently, an updated version of the SD-2 shoulder, known as the 
SD-3, was designed and fabricated as part of the European Union's 
Thoracic Injury Assessment for Improved Vehicle Safety (THORAX) 
project.\101\ Changes introduced in the SD-3 design included redesigned 
sterno-clavicular joint anthropometry, an updated shoulder cover, and 
improvements intended to address the durability and usability concerns 
raised by the University of Virginia testing. These latter improvements 
consisted of replacing the clavicle U-joint with a spherical joint; 
replacing the humerus joint with a metric version of the HIII-50M upper 
arm joint; and introducing a series of washers and bushings to the 
bottom of the vertical shaft to enable the resistance of the assembly 
to be adjusted to allow a more reproducible initial position.
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    \101\ Lemmen, P., Been, B., Carroll, J., Hynd, D., Davidsson, 
J., Song, E., and Lecuyer, E. (2012). Development of an advanced 
frontal dummy thorax demonstrator. Proceedings of the 2012 IRCOBI 
Conference, Paper No. IRC-12-87, September 2012.
---------------------------------------------------------------------------

    The SD-3 shoulder was installed on a THOR-50M ATD and sled testing 
was again carried out at the University of Virginia in the Gold 
Standard 1 and Gold Standard 2 conditions, as well as a variation of 
Gold Standard 1 with a force-limited belt.\102\ The SD-3 shoulder 
assembly was inspected in detail throughout this testing, and no 
evidence of damage was identified. The chest deflection and torso 
motion was similar to the SD-1 and SD-2 shoulders, while durability was 
improved. NHTSA also conducted an evaluation of blunt thoracic impact 
response of several configurations of THOR-50M ATDs and found the 
iteration with the SD-3 shoulder assembly installed to have the highest 
qualitative and quantitative biofidelity.\103\ Given these findings, 
NHTSA modified the drawing package to include the SD-3 shoulder. The 
first iteration of the drawing package to include the SD-3 shoulder was 
published as the September 2014 version.\104\
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    \102\ Crandall, J. (2013). ATD Thoracic Response: SD3 Shoulder 
Evaluation. NHTSA Biomechanics Database, Report b11470R001, 
available at: https://www-nrd.nhtsa.dot.gov/database/MEDIA/GetMedia.aspx?tstno=11470&index=1&database=B&type=R.
    \103\ Parent, D., Craig, M., Ridella, S., McFadden, J., 
``Thoracic Biofidelity Assessment of the THOR Mod Kit ATD,'' The 
23rd Enhanced Safety of Vehicles Conference, Paper No. 13-0327, 
2013.
    \104\ National Highway Traffic Safety Administration (2014). 
THOR 50th Percentile Male Drawing Package, September 2014. available 
at: https://www.nhtsa.gov/DOT/NHTSA/NVS/Biomechanics%20&%20Trauma/THOR%20Advanced%20Crash%20Test%20Dummy/thoradv/THOR-M_PDF_2014-09-29.pdf.
---------------------------------------------------------------------------

    After the publication of the September 2014 drawing package, 
Humanetics filed an application for a patent describing a shoulder 
assembly as well as an upper arm with an integrated load cell.\105\ 
Similar to the SD-3 shoulder, the design patent describes a shoulder 
pivot assembly which includes, among other things, a coil spring and an 
adjustable resistance element. After discussions between NHTSA and 
Humanetics, a disclaimer stating that portions of the THOR-50M drawings 
were covered by a Humanetics patent was added first to the NHTSA 
website where the drawings were available for download, and later to 
the drawings for the shoulder and upper arm assemblies in the drawing 
package itself.
---------------------------------------------------------------------------

    \105\ Been, B., & Burleigh, M. (2017). U.S. Patent No. 
9,799,234. Washington, DC: U.S. Patent and Trademark Office.
---------------------------------------------------------------------------

    NHTSA has generally avoided specifying such parts, consistent with 
the legislative history of the Safety Act. (See Section VIII, 
Intellectual Property.) For this reason, as explained below we are also 
proposing, in addition to the SD-3 shoulder, an alternative shoulder 
pivot assembly design.
Alternate Shoulder Pivot Assembly Design
    To address the potential issues with specifying only a proprietary 
shoulder design, NHTSA has designed, built, and tested an alternate 
shoulder pivot assembly that is not subject to any intellectual 
property claims. The alternate shoulder pivot assembly does not include 
any components to adjust the resistance of the assembly, and does not 
use a coil, clock, or watch-spring mechanism. Instead, the alternate 
shoulder pivot assembly design uses a molded rubber cylinder acting as 
a torsion bar. The top of the cylinder is attached to the shoulder 
support assembly and the bottom is attached to the spring housing, so 
rotation of the shoulder about the local Z-axis of the ATD results in 
torsion of the rubber cylinder. In order to adjust the resistance of 
the assembly, the springs must be removed and replaced.
    NHTSA has evaluated the alternate shoulder in a variety of tests 
and tentatively concludes that its performance is similar to the SD-3 
shoulder based on testing carried out to date. This testing, which 
included a partial qualification test series and sled tests, is briefly 
summarized below. A more detailed discussion of this material is 
available in a testing report that NHTSA is preparing, and which will 
be placed in the research docket when it is completed. NHTSA is also 
preparing another report that describes additional sled testing that 
was conducted; this report will be placed in the research docket when 
it is complete.
    First, the alternate shoulder was installed in a THOR-50M without 
any issues regarding the form, fit, or function. Second, in a quasi-
static rotation test, the alternate shoulder showed a similar moment-
rotation loading slope to the SD-3 shoulder in both the forward and 
rearward rotation directions. Third, the SD-3 and alternate shoulder 
showed nearly identical longitudinal motion in all three loading 
directions in a quasi-static biofidelity evaluation comparing each

[[Page 61911]]

shoulder's range of motion to that of human volunteers; the responses 
of both were generally similar to the human volunteer response 
corridors. Fourth, the qualification tests most likely to be affected 
by shoulder response (upper thorax and chest) were carried out; the 
THOR-50M with the alternate shoulder met all qualification 
specifications for the upper thorax, and the force-deflection 
characteristic of the chest was nearly identical to that of a THOR-50M 
with the SD-3 shoulder. Finally, sled tests conducted in both a full 
frontal and a far-side oblique condition did not reveal any durability 
or usability issues, and the response of the THOR-50M with the 
alternate shoulder was within the test-to-test variation of the THOR-
50M with the SD-3 shoulder.
    NHTSA is therefore proposing the alternative shoulder as an 
acceptable optional subassembly. The shoulder assemblies are specified 
on drawings 472-3810 (left) and 472-3840 (right). Each shoulder 
assembly drawing specifies that either the SD-3 shoulder pivot assembly 
or the alternate shoulder pivot assembly may be used. The proposed 
specifications for the SD-3 shoulder pivot assembly are provided in 
drawings 472-3811 and 472-3841, and the proposed specifications for the 
alternate shoulder pivot assembly are provided in drawings 472-6810-1 
and 472-6810-2. The drawing package currently indicates that the 
selection of which shoulder pivot assembly to use is made separately 
for the left and right shoulder assemblies, so that the dummy could be 
fitted with the SD-3 shoulder pivot assembly on one side, and the 
alternate shoulder pivot assembly on the other side. The dummy has not 
been tested in such a mixed configuration, and the overall effects of 
such configurations are unknown. NHTSA seeks comment on whether the 
final specifications should allow such mixed configurations.
    NHTSA seeks comment on whether the final drawing package should 
include the SD3 shoulder, the alternate shoulder, or both. NHTSA also 
seeks comment from THOR-50M users who have evaluated the proposed 
alternate shoulder design, or other alternate shoulder designs, and 
have data related to equivalence with respect to durability, 
repeatability and reproducibility, and response in qualification, 
biofidelity, injury and vehicle crash test conditions.
2. Shoulder Slip
    NHTSA is aware that some researchers and regulatory authorities 
have identified what they view as a possible design flaw in the 
shoulder--that the shoulder belt may slip towards the neck in a crash--
and have developed potential modifications to the shoulder design to 
prevent this from happening.
    This concern was first raised in a 2018 conference paper describing 
research conducted by Transport Canada. Transport Canada conducted a 
series of vehicle crash tests with the THOR-50M in the driver seat in 
two conditions: 40% offset and full frontal rigid barrier.\106\ It was 
reported that the upper portion of the shoulder belt could translate 
towards the neck and become entrapped in the gap between the neck and 
the shoulder. This occurred in 33 of the 45 offset tests and in 2 of 
the 13 full frontal rigid barrier tests. Compared to tests without 
shoulder belt slip, tests with shoulder belt slip showed higher 
measurements for lower neck shear (X-axis and Y-axis force), higher 
chest deflections in the upper left and lower right quadrants, and 
lower clavicle axial forces.
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    \106\ Tylko, S., Tang, K., Giguere, F., Bussieres, A. (2018). 
Effects of Shoulder-belt Slip on the Kinetics and Kinematics of 
THOR. Proceedings of the 2018 IRCOBI Conference.
---------------------------------------------------------------------------

    Following that research, a 2019 Humanetics study identified and 
evaluated three prototype alternative modifications to the shoulder 
specified in the 2018 drawing package to prevent the shoulder belt from 
entering the gap between the neck and the shoulder.\107\ The study 
concluded that all three prototype modifications prevented belt 
entrapment and identified the preferred design alternative (referred to 
as a profiled split design). While the shoulder specified by NHTSA uses 
the same material for the entire shoulder pad, the profiled split 
design replaces the material closest to the neck with a higher-
stiffness plastic material. This is intended to prevent the collar (the 
portion of the shoulder pad closest to the neck) from deforming and 
allowing the shoulder belt to slip towards the neck.
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    \107\ Wang, Z.J., Fu, S., McInnis, J., Arthur, J. (2019). 
Evaluation of Novel Designs to Address the Shoulder-belt Entrapment 
for THOR-50M ATD. Proceedings of the 2019 IRCOBI Conference.
---------------------------------------------------------------------------

    In addition, in recent discussions with NHTSA, Euro NCAP has noted 
that several instances of shoulder belt slippage were observed in Euro 
NCAP testing as well as research tests with the mobile progressive 
deformable barrier. Euro NCAP reported that it was evaluating two 
potential shoulder design modifications, and expected these to be 
presented for approval in 2023.
    While NHTSA has witnessed the shoulder belt moving towards the neck 
in vehicle crash tests, this phenomenon does not appear to influence 
dummy measurements related to injury criteria. NHTSA seeks comment on 
the desirability of and specifications for a modification to prevent 
belt slippage, including data on testing with the proposed shoulder 
design showing that it is leading to belt slippage that has a 
meaningful effect on test results. NHTSA also requests comment from 
THOR-50M users who have evaluated the split shoulder pad (or any 
available alternatives) and have data to support equivalence of 
durability, repeatability and reproducibility, and response in 
qualification, biofidelity, injury criteria, and vehicle crash test 
conditions.

G. Hands

    The THOR-50M specified in the 2023 drawing package includes the 
same hand design as the HIII-50M. The drawing defining the hand 
assembly of the THOR-50M \108\ includes material formulation (Solid 
Vinyl, Formulation Portland Plastics, PM-7003) along with two two-
dimensional images and one three-dimensional image of the hand. 
Additionally, the three-dimensional geometry of the hand assembly is 
included in the computer-aided design (CAD) files available through the 
NHTSA website in both Autodesk Inventor and generic STEP formats. 
However, the vinyl call-out does not sufficiently specify the hardness 
or the stiffness of the material formulation and may be insufficient to 
define the part. NHTSA therefore seeks comment on whether there is a 
need for a material test (e.g., hardness measurement or a quasi-static 
compression test of a coupon of the material) or performance test 
(e.g., quasi-static or dynamic impact to the as-fabricated hand) to 
further define the hand assembly of the THOR-50M, and if so, what the 
test might be.
---------------------------------------------------------------------------

    \108\ Drawing 472-6900-1/2.
---------------------------------------------------------------------------

H. Spine

    The spine of the THOR-50M ATD is primarily constructed of steel. 
There are two flexible elements (one in the thoracic spine and one in 
the lumbar spine) that are intended to allow human-like spinal 
kinematics in both frontal and oblique loading conditions.\109\ Between 
the two flexible elements is a posture adjustment joint known as the 
lumbar spine pitch change mechanism, which allows the posture of the 
THOR-50M to be adjusted into various seating configurations in three-

[[Page 61912]]

degree increments, including, but not limited to, four designated 
positions (erect, neutral, slouched, and super slouched).\110\ The 
spine is instrumented with a five-axis thoracic spine load cell mounted 
below the lumbar spine pitch change mechanism and above the lumbar 
spine flex joint (a flexible joint that allows the dummy to go into 
flexion/extension in the lumbar region). Triaxial accelerometers can be 
installed in the nominal locations of the first, sixth, and twelfth 
thoracic vertebra.
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    \109\ Haffner, M., Rangarajan, N., Artis, M., Beach, D., 
Eppinger, R., Shams, T. (2001). Foundations and Elements of the 
NHTSA THOR Alpha ATD Design. The 17th International Technical 
Conference for the Enhanced Safety of Vehicles, Paper No. 458.
    \110\ See Fig. 5-32 in the PADI.
---------------------------------------------------------------------------

    The proposed spine design differs from the THOR-50M used by Euro 
NCAP. Whereas the 2023 drawing package specifies a lumbar spine pitch 
change mechanism, TB026 specifies a four-position lumbar spine box or 
an ``alternative spine box'' if ``data has been provided to show 
equivalence between the NHTSA spine assembly and modified spine 
assembly.'' \111\ Humanetics holds a patent on the four-position spine. 
The four-position lumbar spine is not specified further, but it does 
differ from the spine specified by the NHTSA drawings. The spine pitch 
change mechanism specified in the 2023 drawing package allows the spine 
to be set at a multitude of flexion or extension settings, not just 
four. NHTSA understands that the Euro NCAP design is intended to 
accommodate the in-dummy installation of some DAS brands by providing a 
mounting surface for data loggers. THOR-50M units built for Euro NCAP 
are configured with in-dummy DAS systems have the four-position spine.
---------------------------------------------------------------------------

    \111\ Sec.  1.4.3.
---------------------------------------------------------------------------

    NHTSA has tentatively decided not to specify a lumbar spine pitch 
change mechanism limited to four positions for a few reasons. First, 
NHTSA has not inspected, nor has it performed any testing with, the 
four-position spine. Second, NHTSA generally avoids specifying patented 
components in Part 572 (see Section VIII, Intellectual Property). 
Third, the proposed spine specifications provide more adjustability 
than the four-position spine so the dummy may be used in a wider range 
of applications. NHTSA seeks comment on user experience with the four-
position spine, including any data on equivalence with the THOR-50M as 
specified in the 2023 drawing package or biofidelity.
    It is also NHTSA's understanding that members of Working Group 5 
have observed variations in the ATD responses in the upper thorax 
qualification tests that have led to difficulties in meeting the Euro 
NCAP qualification specifications. Some manufacturers have suggested 
that this variation in response is due to variation in the spine flex 
joint (specifically, the vertical displacement (Z-axis) of the ribs is 
too high). One potential cause that has been identified (by Porsche in 
November 2019) is that that the hardness of the material comprising the 
spine flex joint was lower than the specification called for.
    NHTSA's qualification testing did not reveal any issues with 
meeting the upper thorax qualification specifications (See Section 
V.D). In any case, in light of the potential concerns raised within 
Working Group 5 of possible excessive variation in the performance of 
the spine flex joint, potentially traceable to out-of-specification 
materials, NHTSA conducted a limited modeling exercise using the THOR-
50M Finite Element (FE) model to investigate this. This analysis 
suggested that while variation in the lumbar and thoracic spine flex 
joints does influence the thoracic response in both qualification and 
sled test conditions, this variation is smaller than the expected test-
to-test and ATD-to-ATD variation; specifically, a decrease in stiffness 
of the spine flex joints can influence the upper thorax qualification 
response, but by a much smaller magnitude than the width of the 
qualification specifications and test-to-test and ATD-to-ATD 
variations. For more information on this issue and NHTSA's FE 
modelling, please see Appendix B.
    Nonetheless, a research effort is currently underway to assess the 
influence of the lumbar and thoracic spine flex joints in physical 
qualification tests (which would provide additional validation data to 
the computational analysis) and develop isolated dynamic tests of the 
lumbar and thoracic spine flex joints. Based on these results, NHTSA 
could potentially consider adding such a test(s) in the drawing 
package, qualification procedures, or laboratory test procedures. NHTSA 
requests comment from THOR-50M ATD users who have data to demonstrate 
variation in THOR-50M response that is believed to result from spine 
flex joint variation, specifically when the parts evaluated met the 
specifications of the THOR-50M drawing package. Additionally, NHTSA 
requests comment on the need for a thoracic spine and/or lumbar spine 
flex joint specification beyond the geometry and material properties 
defined in the drawing package.

I. Abdomen

    The abdomen of the THOR-50M consists of two components, the upper 
abdomen and the lower abdomen. The lower abdomen is the region between 
the lower thoracic rib cage and the pelvis. The upper abdomen is the 
region on the dummy that represents the lower thoracic cavity, which 
fills the volume that exists between the lowest three ribs, above the 
lower abdomen and in front of the spine. The upper and lower abdomen 
components of THOR-50M are represented by structural fabric bags 
containing foam inserts which define the compression stiffness. Both 
abdomen inserts are anchored posteriorly to the spine, while the upper 
abdomen insert is additionally anchored to the lower rib cage. When the 
lumbar spine pitch change joint is set to the ``slouched'' position, 
the abdomen inserts are in contact with one another; when in the 
``erect'' and ``neutral'' positions, the gap between the abdominal 
inserts is filled with the lower abdomen neutral/erect position foam. 
This gap is also spanned by two steel stiffeners on each side that are 
installed into the torso jacket. The bottom surface of the lower 
abdomen insert is coincident with the pelvis.

J. Pelvis

    The THOR-50M pelvis is designed to represent human pelvis bone 
structure to better represent lap belt interaction,112 113 
and the pelvis flesh is designed to represent uncompressed geometry to 
allow human-like interaction of the pelvis flesh with the vehicle 
seat.\114\ The pelvis assembly is constructed of a steel and aluminum 
structure representing bone surrounded by a molded foam-filled vinyl 
covering representing flesh. The flesh is not physically connected to 
the pelvis bone but is held in place due to the tight fit of 
protrusions of the pelvis bone into recesses in the pelvis flesh, as 
well as circular bosses in the pelvis flesh into recesses in the pelvis 
bone. The pelvis flesh includes a portion of the upper thigh flesh, the 
interior surface of which includes gaps around the femur bone to allow 
articulation of the leg about the hip joint.
---------------------------------------------------------------------------

    \112\ Reynolds, H., Snow, C., Young, J., ``Spatial Geometry of 
the Human Pelvis,'' U.S. Department of Transportation, Technical 
Report No. FAA-AM-82-9, 1982.
    \113\ Haffner, M., Rangarajan, N., Artis, M., Beach, D., 
Eppinger, R., Shams, T., ``Foundations and Elements of the NHTSA 
THOR Alpha ATD Design,'' The 17th International Technical Conference 
for the Enhanced Safety of Vehicles, Paper No. 458, 2001.
    \114\ Shams, T., Rangarajan, N., McDonald, J., Wang, Y., 
Platten, G., Spade, C., Pope, P., Haffner, M., ``Development of THOR 
NT: Enhancement of THOR Alpha--the NHTSA Advanced Frontal Dummy,'' 
The 19th International Technical Conference for the Enhanced Safety 
of Vehicles, Paper No. 05-0455, 2005.
---------------------------------------------------------------------------

    The THOR-50M pelvis flesh is a molded component, with a vinyl outer

[[Page 61913]]

layer filled with expandable polyurethane foam. The two-dimensional 
drawing includes top, side, front, and isometric views of the molded 
pelvis flesh, while its three-dimensional geometry is included in the 
CAD files available through the NHTSA website in both Autodesk Inventor 
and generic STEP formats. The drawing package specifies part weight and 
foam density \115\ but not a material response or performance 
requirement for the pelvis flesh.
---------------------------------------------------------------------------

    \115\ Drawing 472-4100.
---------------------------------------------------------------------------

    NHTSA is considering adding a performance specification for the 
pelvis flesh similar to that defined in the HIII-50M PADI. Such a 
performance specification would dictate the amount of allowable 
compression of the pelvis flesh under a defined load. A similar test 
was conducted on the pelvis flesh during the THOR Alpha design 
development.\116\ One such possible requirement would be the 
compression at a force of 500 N. Alternatively, Porsche has suggested a 
dynamic impact test using an impactor similar to that used in the upper 
thorax qualification test to impact the bottom of the pelvis flesh at a 
velocity of 2 m/s. NHTSA seeks comment on the need and specifications 
for a pelvis compression test, including whether it should be a 
qualification requirement, a drawing specification, or otherwise.
---------------------------------------------------------------------------

    \116\ White Jr, R.P., Rangarajan, N., Haffner, M., ``Development 
of the THOR Advanced Frontal Crash Test Dummy'', 34th Annual SAFE 
Symposium, Conference paper, 1996.
---------------------------------------------------------------------------

    The pelvis is instrumented with bi-lateral triaxial load cells 
attached to the acetabulum (in order to measure the reaction force 
between the femur and the pelvis) and a triaxial accelerometer array at 
its center of gravity. The pelvis is also instrumented with bi-lateral 
anterior-superior iliac spine (ASIS) load cells that measure contact 
force in a nominally longitudinal axis and moment about a nominally 
lateral axis. The ASIS load cell is primarily used to measure the force 
transferred to the pelvis through the lap belt, in which case the 
moments can be used to determine the vertical level or center of 
pressure of the lap belt force.

K. Upper Leg

    The upper leg assembly is constructed of steel and aluminum and 
includes a rubber compressive element at the middle of the femur shaft. 
This compressive element consists of a steel plunger that can translate 
axially along the femur shaft through a guide system. When the femur is 
loaded in axial compression (e.g., pushing the knee towards the pelvis 
parallel to the femur), the motion of the plunger is resisted by a 
rubber element, which allows a human-like compression response.\117\ At 
the proximal end, the femur is connected to the pelvis through a ball 
joint in a socket attached to the acetabulum load cell. At the distal 
end, there is a six-axis load cell attaching the femur to the knee 
assembly.
---------------------------------------------------------------------------

    \117\ Ridella, S., Parent, D., ``Modifications to Improve the 
Durability, Usability, and Biofidelity of the THOR-NT Dummy,'' The 
22nd International Technical Conference for the Enhanced Safety of 
Vehicles, Paper No. 11-0312, 2011. See Figure 17.
---------------------------------------------------------------------------

L. Knee

    The THOR-50M knee is similar in construction to that of the HIII-
50M, with a few differences. The primary structure of the knee cap is 
fabricated from aluminum, attached proximally to the femur load cell. 
Inside of the kneecap assembly, a slider mechanism is installed to 
allow translational motion of the tibia with respect to the knee. The 
knee slider includes a stop assembly to prevent metal-to-metal contact 
and to define the force-deflection characteristic of the tibia 
translation. Attached to the slider is a string potentiometer to 
measure the magnitude of tibia translation relative to the knee. The 
sides of the kneecap are enclosed by urethane covers to protect the 
slider mechanism, and the knee assembly is wrapped in a foam-filled 
vinyl cover representing knee flesh.
    The design of the knee slider modifies the HIII-50M design by 
changing the geometry and material properties of the molded slider 
assemblies (472-5320 and 472-5330) and stop assemblies (472-5358).\118\ 
This change was made because at levels of knee displacement below the 
10.2-millimeter (mm) biofidelity response requirement, the HIII-50M has 
been found to be stiffer than PMHS response corridors. Thus, during the 
THOR-50M Mod Kit project, biomechanical response requirements were 
specified with an additional measurement point at 5 mm of knee 
displacement with a force between 100 and 500 N. The Mod Kit also 
relegated the measurement point at 10.2 mm of deflection to a secondary 
requirement, as it was shown to be at the high end of the underlying 
PMHS corridors. While the 5 mm and 17.8 mm response requirements were 
met by the revised THOR-50M knee slider,\119\ the force-deflection 
response was below the human response corridor between 8 mm and 15 mm 
of deflection, but above the corridor after 18 mm of deflection.\120\ 
As such, when the biofidelity was evaluated using BioRank, the external 
biofidelity score of 2.282 indicated that the THOR-50M response was 
more than two standard deviations from the PMHS mean response. This 
BioRank score was lower than the corresponding HIII-50M score (1.070). 
This should be taken into consideration when using the THOR-50M to 
evaluate the risk of ligamentous knee injury.
---------------------------------------------------------------------------

    \118\ Id. at Figure 16.
    \119\ Id.
    \120\ See Biofidelity Report, p. 254 (Fig. 45).
---------------------------------------------------------------------------

M. Lower Leg

    The mechanical design of the THOR-50M lower extremity includes a 
compressive rubber section in the tibia shaft, similar to the compliant 
femur section, which provides more biofidelic force transmission from 
the heel to the knee. The spring damper Achilles tendon system aids in 
producing biofidelic ankle motion and torque characteristics. The ankle 
design allows rotation about three axes, representing inversion/
eversion, dorsi/plantar-flexion, and axial rotation, and includes 
molded rubber elements to define the moment/rotation response and limit 
metal-to-metal contact at the extents of the range of motion. Different 
from existing ATDs, the THOR-50M includes a molded shoe design which 
integrates the foot and shoe into a single part. This feature, added in 
the 2016 update to the THOR-50M drawing package,\121\ is intended to 
reduce potential variability in the response of commercially available 
shoes.
---------------------------------------------------------------------------

    \121\ National Highway Traffic Safety Administration (2016). 
Parts List and Drawings THOR-50M Advanced Frontal Crash Test Dummy 
THOR-50M Male August 2016. Docket ID NHTSA-2015-0119-0376.
---------------------------------------------------------------------------

    Euro NCAP TB026 deviates from the proposed drawing package in that 
it specifies the HIII-50M lower legs, including the military 
specification \122\ shoes, knee slider sensor, and roller ball-bearing 
knees. We believe the THOR-50M specifications are preferable, for the 
reasons given above (e.g., biofidelity).
---------------------------------------------------------------------------

    \122\ Specification is not stated in Euro NCAP TB026, but 
believed to be MIL-S-13192P as specified in 49 CFR 571.208 S8.1.8.2.
---------------------------------------------------------------------------

    Each lower leg can be instrumented with five-channel load cells in 
the upper and lower tibia, a uniaxial load cell to measure the Achilles 
cable force, and three rotary potentiometers to measure the rotation of 
the individual ankle joints. Two uniaxial accelerometers can be mounted 
to the tibia and a tri-pack accelerometer assembly can be mounted to 
each foot plate.

N. Data Acquisition System

    Testing with THOR-50M requires (as does testing with any dummy) a 
data

[[Page 61914]]

acquisition system (DAS). The data acquisition system performs signal 
conditioning, triggering, and data collection to store measurements 
from instrumentation installed in the dummy during a test into 
nonvolatile memory. As it relates to ATDs, there are effectively two 
types of DAS: external and internal (or in-dummy). As we explain below, 
while the 2018 drawing package does not specify a DAS (because it 
assumes the use of an external DAS), NHTSA is proposing to specify an 
optional in-dummy DAS.\123\
---------------------------------------------------------------------------

    \123\ We note that the 2023 drawing package itself does not 
contain specifications for an in-dummy DAS. Instead, the proposed 
in-dummy DAS specifications are set out in an addendum that is being 
docketed along with the 2023 drawing package.
---------------------------------------------------------------------------

    An external DAS is, as the name indicates, external to the dummy. 
The instrumentation in the dummy is connected to the external DAS via 
wires, sometimes referred to as an umbilical cable. The 2018 drawing 
package does not explicitly specify a DAS or related equipment, but the 
drawings assume an external DAS: they assume that the instrumentation 
wires are long enough to be bundled into an umbilical cable and 
connected to a DAS located in the lab or mounted to the vehicle in 
which the ATD is seated.
    An internal DAS is installed within the dummy itself. An internal 
DAS has some advantages to an external DAS. The primary advantage is 
related to the mass properties of the dummy. With an internal DAS 
system, there are no external cables that may possibly affect body 
segment masses; segment masses are always the same no matter how the 
dummy is used. While upfront cost is higher, an internal DAS would 
reduce per-test costs, eliminate the need for interface cables to lab-
specific DAS systems (which have been a frequent sources of 
instrumentation failures in research testing), and reduce the 
adjustments needed to arrive at the target test vehicle weight. 
Feedback from industry \124\ as well as Euro NCAP indicates that users 
prefer an in-dummy DAS for its many usability advantages. Euro NCAP 
TB026 requires an in-dummy DAS.\125\ While Euro NCAP TB029 currently 
does not specify an approved in-dummy DAS,\126\ earlier versions of 
TB029 did specify a few different approved in-dummy DAS systems.\127\
---------------------------------------------------------------------------

    \124\ Alliance of Automobile Manufacturers, Inc. (2016). 
Technical Considerations Concerning NHTSA's Proposal to Rework the 
Agency's New Car Assessment Program (NCAP). Regulations.gov Docket 
ID NHTSA-2015-0119-0313, available at: https://www.regulations.gov/contentStreamer?documentId=NHTSA-2015-0119-0313&attachmentNumber=5&contentType=pdf.
    \125\ TB026 Sec.  1.2.
    \126\ European New Car Assessment Programme (2022). Euro NCAP 
Supplier List, Version 4.0, October 2022, TB 029, available at: 
https://www.euroncap.com/en/for-engineers/supporting-information/technical-bulletins/.
    \127\ European New Car Assessment Programme (2022). Euro NCAP 
Supplier List, Version 3.1, April 2021, TB 029, available at: 
https://www.euroncap.com/en/for-engineers/supporting-information/technical-bulletins/. The DTS TDAS G5, SLICE Nano, and SLICE6; the 
Kistler DTI, microDAU, and NXT32; and the Messring M=BUS.
---------------------------------------------------------------------------

    In light of these potential advantages and user preferences, NHTSA 
sponsored development and testing of an in-dummy DAS. NHTSA published a 
request for solicitation for an in-dummy DAS.\128\ This was before Euro 
NCAP began testing with the THOR-50M. The solicitation favored a 
minimal redesign of existing THOR-50M parts, in order to facilitate 
interchangeability of parts between THOR-50Ms with and without in-dummy 
DASs. NHTSA contracted Diversified Technical Systems (DTS) to implement 
its SLICE6 data acquisition system in a NHTSA-owned THOR-50M. This 
included delivery of DAS components, replacement instrumentation 
compatible with the DAS, and replacement ATD parts to allow attachment 
of DAS components and preservation of inertial properties. The 
resulting implementation distributes a series of small 6[hyphen]channel 
data acquisition modules throughout the ATD, mounted directly on load 
cells or sensors where possible, or close to the sensor with short 
cables to the sensor. The DAS modules are chain[hyphen]networked with 
four wiring harnesses which connect to the SLICE6 Distributor, with a 
single ATD exit cable connecting the DAS to the full test system.
---------------------------------------------------------------------------

    \128\ National Highway Traffic Safety Administration (2017). 
Implement and Install THOR 50M In Dummy Data Acquisition System. 
Solicitation Number DTNH2217Q00033, available at https://sam.gov/opp/068c7821de797ebe7f9e78a0f2b68dc4/view.
---------------------------------------------------------------------------

    NHTSA evaluated the overall performance and equivalence of the 
THOR-50M with the in-dummy SLICE6 DAS in a full suite of qualification 
testing and a variety of sled and vehicle crash testing. This research 
and analysis is described briefly below. The vehicle crash testing is 
described in more detail in the cited report. NHTSA is preparing a 
report on the installation, qualification testing, and sled testing of 
the SLICE6 in-dummy DAS, which will be placed in the research docket 
when it is complete. Additional information on the durability of the 
THOR-50M with the in-dummy DAS system is included in Section VII.B, 
Durability and Maintenance.
     It was possible to install the SLICE6 into the dummy with 
negligible changes to the mass, moment of inertia, and center of 
gravity of the ATD and its individual body segments. This did require 
modifications to several THOR-50M parts (e.g., the lower thoracic spine 
assembly) in order to allow attachment of the DAS hardware to the rigid 
components of the ATD.
---------------------------------------------------------------------------

    \129\ Saunders, J., Parent, D. (2023). Update on NHTSA's OMDB's 
half barrier analysis. Proceedings of the 27th Enhanced Safety of 
Vehicle Conference, Yokohama, Japan.
    \130\ The OVSC Laboratory Test Procedures for FMVSS No. 208 
specify an ambient temperature measured within 36 inches of the ATD 
to be between 69 and 72 degrees Fahrenheit. National Highway Traffic 
Safety Administration (2008). Laboratory Test Procedure for FMVSS 
208, Occupant Crash Protection, TP208-14, available at: https://www.nhtsa.gov/sites/nhtsa.gov/files/documents/tp-208-14_tag.pdf.
---------------------------------------------------------------------------

     NHTSA has been able to fully qualify THOR-50M ATDs with 
the in-dummy DAS installed. Since the SLICE system has been installed, 
we have used the dummy in many tests and have qualified it with no 
issues. The THOR-50M with the in-dummy DAS was tested in simplified 
sled tests. Sled tests were conducted in the Gold Standard 1 (40 km/h, 
12g peak pulse, standard lap and shoulder belt) and Gold Standard 2 
(30km/h, 9g peak pulse, 3kN load limited shoulder belt) test 
conditions, which were used both in biofidelity assessment and in the 
development of thoracic injury criteria. The goal of this testing was 
to determine if any differences occurred between the external and 
internal DAS configurations, and if so, whether the magnitude of these 
differences would affect the biofidelity and injury criteria 
development analyses.
     NHTSA also tested the THOR-50M with an in-dummy DAS in a 
series of vehicle crash tests in the OMDB test condition with three 
different deformable barrier faces. While some of the OMDB tests 
appeared to show differences between the in-dummy DAS and umbilical 
configurations, it was not clear whether this was due to variation in 
the dummy response or variation in dummy positioning, vehicle response, 
and/or restraint system response.\129\
    Importantly, this testing did not reveal any potential durability 
or usability issues associated with the in-dummy DAS, with one possible 
exception: The temperature inside the thoracic cavity of the ATD can 
increase beyond the ambient temperature typically prescribed for 
regulatory and consumer information crash tests.\130\ In a more recent 
set of vehicle crash tests, NHTSA closely monitored the rib temperature 
of the THOR-50M with the

[[Page 61915]]

in-dummy DAS.\131\ By routinely limiting the ``ON'' time of the DAS, 
NHTSA has been able to maintain the temperature range. Additionally, 
NHTSA has used a portable fume extractor device to aid in maintaining 
the temperature of the WorldSID-50M side impact dummy, which also has 
internal DAS system.132 133 This device may also be employed 
in tests with the THOR-50M.
---------------------------------------------------------------------------

    \131\ Saunders, J., Parent, D., Martin, P. (2023). THOR-50M 
fitness assessment in FMVSS No. 208 unbelted crash tests. 
Proceedings of the 27th Enhanced Safety of Vehicle Conference, 
Yokohama, Japan.
    \132\ Tatem, W., Louden, A. (2023). WorldSID-50M Fitness 
Assessment in FMVSS No. 214 Moving Deformable Barrier and Oblique 
Pole Crash Tests. Proceedings of the 27th Enhanced Safety of Vehicle 
Conference, Yokohama, Japan.
    \133\ This device is used to dissipate heat from the dummy in 
the pre-test setup (for example, while seating and positioning the 
dummy). Typically, a tube is inserted into the dummy jacket and in 
conjunction with the fan is used to vent heat from the dummy to 
maintain an in-spec internal temperature. The apparatus is detached 
from the dummy immediately prior to the vehicle or sled test. Use of 
such a fan may be specified in the OVSC laboratory test procedure.
---------------------------------------------------------------------------

    Based on this testing, NHTSA has tentatively concluded that the 
THOR-50M with the in-dummy DAS is equivalent to one with the external 
DAS. NHTSA is therefore proposing an internal DAS as permitted optional 
instrumentation that it could use in its testing. This necessitates 
changes to the dummy to accommodate the DAS while ensuring that there 
are no changes to the mass, moment of inertia, and center of gravity of 
the ATD and its individual body segments. These changes may differ from 
the Euro NCAP approach specified in TB026, which permits the four-
position spine box (discussed in Section III.H above) to accommodate 
the installation of some DAS brands by providing a mounting surface for 
data loggers. Euro NCAP does not provide part-by-part engineering 
drawings of the various DAS packages, which is necessary for THOR-50M 
to be sufficiently objective.
    NHTSA has therefore provided, in an addendum to the 2023 drawing 
package, further specifications for the dummy to accommodate an 
internal DAS. It is anticipated that, upon finalization of this 
proposal, the in-dummy DAS drawings will be fully integrated within the 
relevant technical data package components. These specifications 
consist of descriptions of the instrumentation and new drawings for the 
dummy parts that require modifications to accommodate the DAS. The 
changes are specified such that the dummy with the in-dummy DAS will 
have the same inertial properties as the dummy using the external DAS. 
The drawings show DAS mass blanks in lieu of the actual DAS components 
(battery, data logger, etc.) with the exterior dimensions of the blank 
matching those of the corresponding SLICE6 component.
    If an in-dummy DAS component is not installed (for example, if 
lower leg instrumentation is not needed for a given test mode), the 
blank would be filled with a material of a specified density. The 
material of the blank is not specified (although a reference 
specification is provided) but would be selected to provide an 
appropriate density and may also have internal flashing holes needed to 
attain the desired mass, which is chosen to match the mass of the 
actual DAS component. It is anticipated that, upon finalization of this 
proposal, the PADI will show two sets of installation steps: one with 
the ``blank'' component, and one with the actual DAS parts. (This two-
set convention is also followed with load cells and their structural 
replacements). The proposed specifications are based on, but not 
necessarily limited to, the SLICE6 (the SLICE6 is not explicitly 
specified or called-out by name), so that another system fitting within 
the defined specifications could also be utilized.\134\
---------------------------------------------------------------------------

    \134\ While we are aware of in-dummy DASs produced by other 
manufacturers, we have not evaluated whether these systems would be 
compatible with the in-dummy DAS addendum to the 2023 drawing 
package.
---------------------------------------------------------------------------

    NHTSA seeks comment from users who have experience with both 
umbilical and in-dummy DAS configurations of the THOR-50M, as to 
whether they have seen any quantifiable differences between the two. 
NHTSA also seeks comment on whether any additional changes should be 
made to the proposed drawings specifying the in-dummy DAS to make it 
more amenable to additional DAS systems that are already in the field.

IV. Biofidelity

    Biofidelity is a measure of how well the dummy replicates a human, 
and includes anthropometry, mass properties, range of motion, and 
impact response. The impact biofidelity is evaluated by comparing the 
response of the dummy to the response of a post-mortem human surrogate 
(PMHS or cadaver) or human volunteer in a variety of different test 
conditions (also referred to as test modes). Some of these tests focus 
on individual dummy components (head, neck, chest, abdomen, upper leg, 
knee, lower leg) and some evaluate the entire dummy as a complete 
assembly.
    To evaluate the biofidelity of THOR-50M, NHTSA selected test 
conditions based on relevance to frontal and frontal oblique crash test 
applications and the availability of data. For example, a neck frontal 
flexion test was conducted by attaching the base of the THOR-50M neck 
to a sled and applying a certain acceleration pulse. This was then 
compared to the response measured on human volunteers who were 
subjected to a similar pulse. Specifically, the impact biofidelity of 
the THOR-50M was assessed in twenty-one test conditions. The test 
conditions are summarized in Table 6. Each test produces a series of 
data points (e.g., force vs. time).
    The test conditions have been developed over the years by various 
researchers to evaluate biofidelity and have been published in peer-
reviewed journals. The PMHS and human volunteer response data generally 
comes from this published research. The THOR-50M response data comes 
from testing that NHTSA has been conducting on the THOR-50M throughout 
its development, all of which is available in NHTSA's Biomechanics Test 
Database.\135\ NHTSA also compared THOR-50M's biofidelity to that of 
the HIII-50M; many of the tests conducted with THOR-50M were paired 
with the same test conducted on the HIII-50M. In our testing we 
attempted to match the test conditions as closely as possible to the 
test conditions in the original PMHS or volunteer tests.\136\
---------------------------------------------------------------------------

    \135\ Available at https://www.nhtsa.gov/research-data/research-testing-databases#/biomechanics.
    \136\ Overall, while some assumptions were necessary in the 
reproduction of the PMHS or volunteer test conditions, we believe 
that these assumptions should not affect the overall biofidelity 
assessment of the THOR-50M. For instance, NHTSA simplified some of 
the original tests in order to facilitate ease of testing when we 
expected the simplification to have a negligible influence on the 
result, such evaluating neck flexion using only the ATD's head and 
neck, and not the entire dummy. These assumptions and 
simplifications, as well as any limitations to our analyses, are 
discussed in detail in the docketed biofidelity report. Parent, D., 
Craig, M., Moorhouse, K. 2017. Biofidelity Evaluation of the THOR 
and Hybrid III 50th Percentile Male Frontal Impact Anthropomorphic 
Test Devices. Stapp Car Crash Journal, 61, 227-276, available at: 
https://www.regulations.gov/document/NHTSA-2019-0106-0004.

[[Page 61916]]

  Table 6--Biofidelity Conditions Considered in the Design of the HIII
                    Frontal Dummies and THOR-50M ATDs
------------------------------------------------------------------------
                                                       Subpart
         Body region               Test condition      E, O, W  THOR-50M
------------------------------------------------------------------------
Head.........................  Isolated Head Drop...    
                               Whole-body Head        ........  
                                Impact.
                               Face Rigid Bar.......  ........  
                               Face Rigid Disk......  ........  
Neck.........................  Neck Flexion,            ........
                                Pendulum.
                               Neck Extension,          ........
                                Pendulum.
                               Neck Frontal Flexion,  ........  
                                Sled.
                               Neck Lateral Flexion,  ........  
                                Sled.
                               Neck Torsion.........  ........  
Thorax.......................  Sternal Impact, 6.7 m/   ........
                                s.
                               Sternal Impact, 4.3 m/ ........  
                                s.
                               Lower Ribcage Oblique  ........  
Abdomen......................  Upper Abdomen          ........  
                                Steering Rim.
                               Lower Abdomen Rigid    ........  
                                Bar.
                               Abdomen Belt Loading.  ........  
KTH..........................  Femur Compression....    
                               Knee Shear...........    
Lower Extremity..............  Dynamic Heel Impact..  ........  
                               Tibia Axial            ........  
                                Compression.
                               Dynamic Dorsiflexion.  ........  
Whole-body...................  Gold Standard 1......  ........  
                               Gold Standard 2......  ........  
                               Gold Standard 3......  ........  
                               Far Side Oblique.....  ........  
------------------------------------------------------------------------

    The test conditions used to evaluate the THOR-50M represent an 
accumulation of biomechanics research. All conditions are accompanied 
by a well-specified, objective test procedure and a well-founded set of 
human response targets. The set of test conditions has grown 
substantially over the span of Part 572 rule makings. For example, in 
NHTSA's original 1998 proposal for the Subpart O HIII-5F dummy,\137\ 
only six biofidelity conditions were assessed.\138\ Since then, the 
list has grown substantially; new conditions have been developed for 
all body regions, and whole-body sled test conditions have been 
developed.\139\
---------------------------------------------------------------------------

    \137\ 63 FR 46981.
    \138\ Mertz, H.J., Irwin, A.L., Melvin, J.W., Stanaker, R.L., & 
Beebe, M. (1989). Size, weight and biomechanical impact response 
requirements for adult size small female and large male dummies (No. 
890756). SAE Technical Paper.
    \139\ See National Highway Traffic Safety Administration, 
``Biomechanical Response Requirements of the THOR NHTSA Advanced 
Frontal Dummy, Revision 2005.1,'' Report No: GESAC-05-03, U.S. 
Department of Transportation, Washington, DC, March 2005 (available 
at http://www.nhtsa.gov/DOT/NHTSA/NVS/Biomechanics%20&%20Trauma/THOR-NT%20Advanced%20Crash%20Test%20Dummy/thorbio05_1.pdf) and 
Ridella, S., Parent, D., ``Modifications to Improve the Durability, 
Usability, and Biofidelity of the THOR-NT Dummy,'' The 22nd 
International Technical Conference for the Enhanced Safety of 
Vehicles, Paper No. 11-0312, 2011.
---------------------------------------------------------------------------

    NHTSA quantified how closely the response of the THOR-50M matched 
the response of the PMHS or human volunteers using the Biofidelity 
Ranking system (BioRank).\140\ BioRank has been applied in other 
instances cited in the literature \141\ and in other NHTSA Part 572 
rulemakings.\142\ This methodology statistically compares the dummy 
response to the average PMHS/volunteer response (typically a time-
series but sometimes a point estimate). A BioRank value of 0.0 
indicates an ATD response identical to the average PMHS/volunteer 
response; a value of 1.0 indicates an ATD response that is on average 
one standard deviation \143\ away from the average PMHS/volunteer 
response; a value of 2.0 indicates an ATD that is on average two 
standard deviations away from the average PMHS/volunteer response; and 
so on. Therefore, the lower the BioRank value, the better the 
biofidelity. We computed BioRank scores for both the THOR-50M and the 
HIII-50M.
---------------------------------------------------------------------------

    \140\ Rhule, H., Maltese, M., Donnelly, B., Eppinger, R., 
Brunner, J., Bolte, J. (2002) Development of a New Biofidelity 
Ranking System for Anthropomorphic Test Devices. Stapp Car Crash 
Journal 46: 477-512.
    \141\ Rhule, H., Moorhouse, K., Donnelly, B., Stricklin, J. 
(2009) Comparison of WorldSID and ES-2RE Biofidelity Using Updated 
Biofidelity Ranking System. 21st ESV Conference, Paper No.09-0563.
    \142\ The analysis using Biorank described here mirrors (with 
some exceptions) the approach used in the assessment of the WorldSID 
50th ATD. See, e.g., 80 FR 78522, 78538 (Dec. 16, 2015) (New Car 
Assessment Program Request for Comments); 71 FR 75304 (Dec. 14, 
2006) (final rule for ES-2re Side Impact Crash Test Dummy 50th 
Percentile Adult Male); 71 FR 7534 (Dec. 14, 2006) (final rule for 
SID-IIs Side Impact Crash Test Dummy 5th Percentile Adult Female).
    \143\ The standard deviation is a statistic that measures the 
dispersion of a dataset relative to its mean.
---------------------------------------------------------------------------

    For each body region, we calculated two BioRank scores: one for 
external biofidelity (the extent to which the ATD represents a human 
surrogate to the vehicle or restraint system); and one for internal 
biofidelity (the ability of the ATD to represent the human responses 
that relate to prediction of injury). External biofidelity measures are 
generally those recorded at the test fixture level, such as pendulum 
force or belt force; internal biofidelity measures are generally those 
recorded by the internal instrumentation of the ATD or test equipment 
such as motion tracking that records subject excursion.
    NHTSA considered two other methods of quantifying biofidelity. One 
is the International Standards Organization (ISO) 9790 Biofidelity 
Classification System. ISO 9790 defines the analysis process, response 
corridors, and weighting factors for the quantitative assessment of 
biofidelity of side impact ATDs. Because the ISO 9790 response 
corridors and weighting factors are specific to side-impact ATDs, it 
could not be directly applied to a frontal impact ATD such as the THOR-
50M, and we are not aware of a corollary ISO standard for assessment of 
frontal impact ATD biofidelity. While a method similar to that 
described in ISO 9790 could be developed to assess frontal impact ATD 
biofidelity, we believe such a method may introduce subjective bias 
because it contains many subjective features, including weighting

[[Page 61917]]

of test conditions and body regions.\144\ The BioRank system was 
developed to minimize subjectivity in the areas of corridor 
development, weighting, and scoring. Another method NHTSA considered is 
correlation and analysis (CORA), which may be a useful tool to carry 
out quantitative analysis.\145\ However, the vast array of tunable 
parameters in the software can result in unintentional subjectivity and 
poor reproducibility. Further, there are no known and accepted 
relationships between CORA scores and biofidelity classifications. 
Accordingly, we evaluated biofidelity using BioRank.
---------------------------------------------------------------------------

    \144\ Rhule, D., Rhule, H., Donnelly, B. (2005) The Process of 
Evaluation and Documentation of Crash Test Dummies for Part 572 of 
the Code of Federal Regulations. 19th ESV Conference, Paper No. 05-
0284, pp. 9-10.
    \145\ Gehre C, Gades H, Wernicke P (2009) Objective rating of 
signals using test and simulation responses, The 21st International 
Technical Conference for the Enhanced Safety of Vehicles, Paper No. 
09-0407, 2009.
---------------------------------------------------------------------------

    We note that because many of the biofidelity test conditions 
utilize specialized instrumentation or test equipment, they are not 
intended to be carried out as certification or qualification tests 
conducted between crash tests or sets of crash tests to confirm that 
specified ATD response requirements are met. Instead, due to its 
relative complexity, biofidelity testing is carried out at the ATD 
design stage to assess the biofidelity of the design. Simplified and 
standardized versions of the biofidelity test conditions have been 
developed as qualification procedures for some body regions. Because 
the qualification response requirements are based on the expected 
variation in response of the ATD, not the underlying human response, 
the qualification requirements specify a much smaller allowable range 
in response than the biomechanical design targets. Therefore, it is 
expected that all THOR-50M units that meet the specifications of the 
qualification procedures would demonstrate similar biofidelity. The 
proposed qualification response requirements are discussed in Section 
V.
    A full description of NHTSA's biofidelity testing and analysis can 
be found in the docketed biofidelity report.\146\ We note that there 
are no separate discussions in the report for the shoulder, spine, or 
pelvis. Impact biofidelity of the spine and pelvis, as well as the 
dynamic biofidelity of the shoulder, are intrinsically evaluated as 
part of the whole-body biofidelity sled test series.\147\ Shoulder 
biofidelity has also been assessed quasi-statically and found to be 
more similar to the human volunteer corridors than existing ATDs. NHTSA 
is finalizing a report on the alternate shoulder design, which includes 
the biofidelity evaluation described here; once complete, this report 
will be published to the research docket.
---------------------------------------------------------------------------

    \146\ Parent, D., Craig, M., Moorhouse, K. 2017. Biofidelity 
Evaluation of the THOR and Hybrid III 50th Percentile Male Frontal 
Impact Anthropomorphic Test Devices. Stapp Car Crash Journal, 61, 
227-276, available at: https://www.regulations.gov/document/NHTSA-2019-0106-0004.
    \147\ The qualitative biofidelity of the shoulder is also 
discussed in the Biofidelity Report, where the role of the shoulder 
in belt retention (or lack thereof) is discussed qualitatively. See 
p. 272-273.
---------------------------------------------------------------------------

    NHTSA believes that the THOR-50M is sufficiently biofidelic for 
incorporation into Part 572. The biofidelity report shows that the 
THOR-50M exhibits overall internal and external BioRank scores of below 
2.0. See Table 7. Both internal and external BioRank scores are lower 
than those of the HIII-50M, which is defined in Part 572 (Subpart E) 
and used in regulatory and consumer information frontal impact crash 
testing. At the body region level, the internal and external BioRank 
scores for THOR-50M are all below 2.0 except for neck internal 
biofidelity and abdomen external biofidelity. The THOR-50M BioRank 
score for the neck and abdomen external biofidelity are, however, lower 
(better) than those for the HIII-50M. Overall, the internal BioRank 
scores for the THOR-50M were lower than those of HIII-50M in 5 of the 7 
body regions evaluated, and THOR-50M external BioRank scores were lower 
than those of HIII-50M in 6 of the 7 body regions evaluated. Thus, the 
THOR-50M has generally improved biofidelity in the individual body 
region tests, which improves the accuracy of injury predictions. The 
THOR-50M and the HIII-50M have comparable quantitative biofidelity in 
the whole-body sled test conditions.\148\
---------------------------------------------------------------------------

    \148\ This finding has been confirmed by independent research; a 
2018 study showed that the HIII-50M and THOR-50M demonstrated 
similar biofidelity scores in a sled test environment representing a 
production vehicle. See Albert, Devon L., Stephanie M. Beeman, and 
Andrew R. Kemper. ``Occupant kinematics of the Hybrid III, THOR-M, 
and postmortem human surrogates under various restraint conditions 
in full-scale frontal sled tests.'' Traffic Injury Prevention 
19.sup1 (2018): S50-S58.

                           Table 7--Body Region Internal and External BioRank Summary
----------------------------------------------------------------------------------------------------------------
                                                             THOR-50M                        HIII-50M
                   Body region                   ---------------------------------------------------------------
                                                     Internal        External        Internal        External
----------------------------------------------------------------------------------------------------------------
Head............................................           0.155           1.143           0.013           6.640
Neck............................................           2.155           1.677           2.185           4.318
Thorax..........................................           0.917           0.948           1.603           2.070
Abdomen.........................................           1.470           2.803           1.629           3.474
KTH.............................................           1.400           1.731           3.875           6.667
Lower Extremity.................................           1.349           0.871           0.832           1.108
Whole-body......................................           1.472           1.989           1.576           1.780
                                                 ---------------------------------------------------------------
    Overall.....................................           1.274           1.594           1.673           3.722
----------------------------------------------------------------------------------------------------------------

    Since a majority of the test conditions involved pure frontal 
loading, and several involved oblique and lateral loading (neck lateral 
flexion, neck torsion, lower thorax oblique, Gold Standard 3, and Far 
Side Oblique test conditions), these findings are expected to extend to 
frontal and frontal oblique crash test conditions. The findings may 
not, however, extend to other loading conditions (such as pure lateral 
or rear impacts) without further research.

V. Qualification Tests

    This NPRM proposes qualification tests (also referred to as 
qualification procedures) for THOR-50M. The qualification procedures 
describe a series of impact tests performed on a fully-assembled dummy 
or dummy sub-assembly. The tests assess the components that play a key 
role in the dummy's performance in the intended application of frontal 
and frontal oblique crashes. We propose

[[Page 61918]]

qualification tests for the head, face, neck, upper thorax, lower 
thorax, abdomen, upper leg, knee, and lower leg. For some body regions 
(such as the face) we propose a single test condition (also referred to 
as a test mode), while for other body regions (for example, the neck) 
we propose a series of different test conditions.
    Each qualification test condition consists of test procedures, test 
parameters, and acceptance intervals. The test procedures describe a 
detailed series of steps that must be carried out to perform the test. 
Test parameters describe specific aspects of the dummy's response. 
Acceptance intervals (or qualification targets) are specified for each 
test parameter. Acceptance intervals are a typically pair of numeric 
values (a minimum value and maximum value) within which the dummy 
response must fall in order to pass, but can also represent a minimum 
or maximum value of the response. For instance, one of the tests 
involves striking the head with an impactor and measuring the head's 
acceleration, which must be within the acceptance interval 117  11.7 Gs.
    The qualification tests mirror the dummy loading patterns observed 
in frontal crash tests, including full frontal, oblique, and offset 
modes. For the neck assembly, we have specified separate requirements 
in flexion, extension, and lateral flexion. These bending modes have 
all been observed in crash testing. Additionally, a torsion test is 
prescribed for the neck since it also twists along its long axis to 
some degree. For the feet and ankles, tests in inversion, eversion, 
dorsiflexion, and axial loading through the tibia are specified to 
account for the various injurious loads that have been observed in 
crash tests. For the head, face, upper and lower thorax, abdomen, upper 
legs, and knees, we have only prescribed impact tests to anterior 
aspects since injurious loads pass primarily through those aspects 
during crash testing. The impact speeds and probe masses have been 
selected to demonstrate that the various body segments work properly at 
energy levels at or near those associated with high injury risks. For 
measurements not associated with an injury criterion, energy levels are 
chosen to exercise the dummy approaching its functionality limits, but 
without causing damage.
    The qualification tests ensure that the dummy is functioning 
properly. There are a few inter-related aspects to this. One is that 
qualification tests ensure that dummy components and sensors are 
properly assembled and functioning. Qualification tests monitor the 
response of components that may have become loosened or misaligned 
since initial assembly. For each test, certain dummy sensors and signal 
characteristics (such as the magnitude and timing) have been specified 
as qualification targets. Loose or misaligned parts may become evident 
when a signal does not conform to the prescribed signal 
characteristics. By monitoring these sensors, the qualification tests 
ensure that the dummy is functioning properly. The tests also ensure 
that the sensors themselves are working properly. Another aspect is 
that qualification tests help identify components that have 
deteriorated over time, preventing the dummy from meeting the 
qualification targets; such parts need to be replaced or refurbished. 
Many of the qualification test protocols are very similar to the 
dynamic tests used to assess biofidelity. This helps to ensure that a 
qualified dummy is also a biofidelic dummy. Finally, they ensure that 
the dummy or particular sub-assembly is responding in a uniform and 
expected manner; if it is not, certain dummy components might need to 
be tuned or adjusted to obtain a response within the qualification 
targets.
    NHTSA's experience has shown that the impact tests on body segments 
are needed to ensure uniformity of dummy responses in a subsequent 
vehicle crash test. In other words, full conformance to part and 
assembly specifications (in accordance with the drawings and PADI) is 
not enough to guarantee a uniform dummy response in a crash test.\149\ 
Qualification tests have proven reliable and sound in qualifying 
NHTSA's other test dummies. Moreover, some of the proposed 
qualification tests use the same test equipment as other ATDs, thus 
minimizing the amount of new qualification equipment needed by test 
laboratories that may already have such equipment in place for 
qualifying other ATDs. Meeting the qualification tests helps ensure 
that the dummy is capable of responding properly in a compliance or 
research test. This in turn helps to ensure that the dummy is an 
objective test device suitable for the assessment of occupant safety in 
compliance tests specified in Federal Motor Vehicle Safety Standards, 
and for other testing purposes.
---------------------------------------------------------------------------

    \149\ At the same time, conformance to a qualification 
requirement is not a substitute for parts that do not conform to 
drawing specifications.
---------------------------------------------------------------------------

    NHTSA proposes setting the qualification targets at  
10% of the mean response for each qualification parameter as reported 
in the qualification test R&R study (discussed in Section VI). In that 
study we subjected multiple dummies to repeated tests in each test 
condition at multiple test laboratories. The repeatability testing and 
analysis for the qualification tests is described in more detail in 
Section VI.A. We believe that 10% is wide enough to account for normal 
variations in ATD and laboratory differences, and narrow enough to 
ensure consistent and repeatable measurements in standardized testing 
with the ATD. This is also consistent with the qualification limits for 
the other Part 572 ATDs. For example, for the Hybrid III 10-year-old 
child dummy, the acceptance intervals are, on average, set at 9.9% from the nominal midpoint, with a low of 8.4% (neck rotation 
in the neck extension test) and a high of 10.8% (in the neck moment in 
the extension test and chest deflection in the thorax impact 
test).\150\ For all Part 572 ATDs, the average acceptance interval is 
11%.
---------------------------------------------------------------------------

    \150\ HIII-10C, Subpart T.
---------------------------------------------------------------------------

    We also considered setting the qualification targets at plus or 
minus two standard deviations from the mean response observed in the 
testing reported in the repeatability and reproducibility study. This 
would have narrowed the acceptance interval for almost all responses, 
some of which would have been unreasonably narrow. For instance, the 
head impact test results in the repeatability and reproducibility study 
were very uniform, with a CV for peak force of 0.9%. If the acceptance 
interval for peak force were set to plus or minus two standard 
deviations (1.8%), 24 of the 26 trials would have resulted 
in a pass; if it were set to 2.5%, all 26 trials would have 
resulted in a pass. This result may have been a function of using only 
three THOR-50M units in the test series, all of which were brand new 
when we tested them. Therefore, we propose a greater allowance of 
10% for all qualification requirements to account for 
slight variations that may arise from equipment and testing variations 
at different test labs as well as a future population of THOR-50M units 
from dummy manufacturers in which lot-to-lot differences in the 
fabrication of parts from the same manufacturer may exist. It also 
allows for slight changes to individual THOR-50M units over time, 
either due to aging of polymeric components or wear and tear under 
normal use. Table 8 summarizes the proposed THOR-50M qualification 
requirements.

[[Page 61919]]

                              Table 8--Proposed THOR-50M Qualification Requirements
----------------------------------------------------------------------------------------------------------------
                                                                                                   Acceptance
              Test                      Measurement               Units        Nominal target       interval
----------------------------------------------------------------------------------------------------------------
1. Head Impact..................  Peak Probe Force.......  N.................            5580          5022-6138
                                  Peak Head CG Resultant   G.................           117.0        105.3-128.7
                                   Acceleration.
2. Face Impact..................  Peak Probe Force.......  N.................            7098          6378-7796
                                  Peak Head CG Resultant   G.................             138            124-152
                                   Acceleration.
3. Neck Flexion.................  Peak Upper Neck My.....  N-m...............            31.0          27.9-34.1
                                  Upper Neck Fz Most       N.................             860            774-946
                                   Positive Value Prior
                                   to 40 ms.
                                  Peak Head Angular        deg/sec...........            1975          1777-2172
                                   Velocity vy (relative
                                   to earth).
                                  Peak Head Rotation       deg...............            64.5          58.1-71.0
                                   (relative to pendulum).
4. Neck Extension...............  Peak Upper Neck My.....  N-m...............            23.0          20.7-25.3
                                  Peak Upper Neck Fz.....  N.................            2918          2626-3210
                                  Peak Head Angular        deg/sec...........            2061          1855-2267
                                   Velocity vy (relative
                                   to earth).
                                  Peak Head Rotation       deg...............            65.0          58.5-71.5
                                   (relative to pendulum).
5. Neck Lateral.................  Upper Neck Mx first      N-m...............            49.7          44.8-54.7
                                   peak after 40.0 ms.
                                  First Peak Head Angular  deg/sec...........            1362          1226-1498
                                   Velocity vx (relative
                                   to earth).
                                  Peak Head Rotation       deg...............            41.7          37.6-45.9
                                   (relative to pendulum).
6. Neck Torsion.................  Peak Upper Neck Mz.....  N-m...............            41.4          37.3-45.6
                                  First Peak Upper Neck    deg/sec...........            1390          1251-1529
                                   Angular Velocity vz
                                   (relative to earth).
                                  Peak Neck Fixture        deg...............            47.9          43.1-52.7
                                   Rotation.
7. Upper Thorax.................  Peak Probe Force.......  N.................            3039             0-3039
                                  Peak Upper Resultant     mm................            53.6          48.3-59.0
                                   Deflection.
                                  Difference Between Peak  mm................               0            -5 to 5
                                   Left & Right Resultant
                                   Deflections.
                                  Force at Peak Resultant  N.................            2677          2409-2944
                                   Deflection.
8. Lower Thorax.................  Peak Probe Force.......  N.................            3484          3136-3832
                                  Resultant Deflection at  mm................            50.9          45.8-56.0
                                   Peak Force.
9. Lower Abdomen................  Peak Probe Force.......  N.................            2918          2626-3210
                                  Lower Abdomen X-axis     N.................            83.0          74.7-91.3
                                   Deflection at Time of
                                   Peak Force.
                                  Difference Between Peak  mm................               0            -8 to 8
                                   Left & Right X-axis
                                   Deflections.
10. Upper Leg...................  Peak Probe Force.......  N.................            8333          7500-9166
                                  Peak Femur Force, Fz...  N.................            4920          4428-5412
                                  Peak Resultant           N.................            2738          2464-3012
                                   Acetabulum Force.
11. Knee........................  Peak Femur Z-axis Force  N.................            6506          5855-7156
                                  Knee Deflection at Peak  mm................            20.2          18.2-22.2
                                   Femur Force.
12. Ankle Inversion.............  Peak Lower Tibia Fz....  N.................             505            454-555
                                  Peak Ankle Resistive     N-m...............            39.1          35.2-43.0
                                   Moment.
                                  Peak Ankle X-axis        deg...............            34.5          31.0-37.9
                                   Rotation.
13. Ankle Eversion..............  Peak Lower Tibia Fz....  N.................             571            514-629
                                  Peak Ankle Resistive     N-m...............            43.0          38.7-47.3
                                   Moment.
                                  Peak Ankle X-axis        deg...............            29.6          26.6-32.5
                                   Rotation.
14. Ball of Foot................  Peak Lower Tibia Fz....  N.................            3170          2853-3487
                                  Peak Ankle Resistive     N-m...............            55.3          49.8-60.8
                                   Moment.
                                  Peak Ankle Y-axis        deg...............            33.8          30.4-37.2
                                   Rotation (in
                                   dorsiflexion).
15. Heel........................  Peak Lower Tibia Fz....  N.................            3162          2846-3478
----------------------------------------------------------------------------------------------------------------
Note: For comparison purposes, unless otherwise noted, only positive values are shown for the Nominal Target and
  Acceptance Range. Some targets, such as Neck Flexion Angular Velocity ([omega]y = -1362 deg/sec), are defined
  by negative values.

    The proposed qualification requirements are the same as the 2018 
version except for the upper leg; this is discussed in the section 
below for the upper leg.
    Euro NCAP TB026 explicitly adopts NHTSA's 2018 qualification 
procedures \151\ with a couple of differences. First, there are a few 
differences between the proposal and TB026 with respect to the tests or 
test parameters. TB026 specifies somewhat different qualification 
metrics for the upper thorax test and does not include a face impact 
test. TB026 prescribes the upper leg test described in NHTSA's 2018 
qualification procedures, which we are proposing to update. And, 
because TB026 specifies the HIII-50M lower extremities, the 
corresponding qualification tests are not the same as those proposed. 
Second, although TB026 adopts the rest of the 2018 qualification test 
procedures and test parameters, it specifies acceptance intervals that 
differ from the proposed acceptance intervals with respect to both the 
width and midpoint of the interval. While the proposed acceptance 
intervals are 10% around the mean (as calculated from our 
R&R testing), the width of the acceptance intervals specified in TB026 
range from 1% to 10%, with many of them less than 10%. In addition, the 
midpoint of these intervals differs from the means NHTSA calculated 
based on its R&R testing. For nine of the parameters, the TB026 
specifications are fully contained within the proposed acceptance 
intervals. Of the remaining parameters, there is a minimum of 82% 
overlap between the Euro NCAP specifications and the proposed 
acceptance intervals. Therefore, it is feasible, but not guaranteed, 
for a THOR-50M which meets the Euro NCAP acceptance intervals to also 
meet the proposed acceptance intervals. NHTSA has tentatively decided 
not to adopt narrower acceptance intervals, such as those specified in 
TB026, for the reasons given above. Moreover, NHTSA is unaware of the 
data on which the Euro NCAP specifications are based, whereas the 
proposed specifications are based on NHTSA's carefully-controlled 
study. The differences between the proposed

[[Page 61920]]

qualification tests and those specified in TB026 are discussed in more 
detail in the relevant sub-sections below. In addition, the proposed 
qualification test parameters and acceptance intervals and the 
corresponding TB026 values are summarized in Appendix G.
---------------------------------------------------------------------------

    \151\ Sec.  2.1.
---------------------------------------------------------------------------

    We propose to set out the qualification procedures in a separate 
document that would be incorporated by reference into Part 572. See 
Section XI, Incorporation by reference. This would be a departure from 
the other ATDs currently specified in Part 572, for which the 
qualification tests are set out in full in the regulatory text in each 
of the relevant paragraphs (corresponding to that ATD) in part 572. We 
are proposing a separate qualification procedures document for THOR-50M 
because the THOR-50M qualification procedures contain many photographs 
and diagrams that are not amenable to publication in the CFR; we 
believe this extra level of detail will be helpful for end users who 
are attempting to qualify the ATD.
    NHTSA seeks comment on the proposed qualification tests. NHTSA also 
seeks any qualification data commenters are able to provide, as long as 
the data are from THOR-50M ATDs conforming to the 2023 drawing package 
and were collected following the April 2023 Qualification Procedures 
Based on any comments and data received, NHTSA might consider changing 
the qualification targets to reflect the larger population of THOR-50M 
units in the field. However, before doing so we would assess the effect 
that any change could have on the biofidelity of the dummy and the 
applicability of injury risk functions. We also seek comment on whether 
we should incorporate the qualification procedures by reference, or 
whether it would be preferable to locate a much-simplified set of 
qualification procedures directly in Part 572 and put additional detail 
and documentation in the Office of Vehicle Safety Compliance (OVSC) 
laboratory test manual or similar document that would not be 
incorporated by reference but instead provided as guidance to DOT 
contractors and other ATD end users.

A. Head Impact

    The head qualification test is identical to the whole-body head 
impact biofidelity assessment, where a fully-assembled THOR-50M is 
seated on a table and impacted on the forehead with a 23.36 kg rigid 
impactor at 2.00  0.05 m/s. This test serves as a surrogate 
for the isolated head drop test used by other ATDs; due to the 
construction of the head and neck of the THOR-50M ATD (specifically, 
the integration of the neck spring cables into the skull), separation 
of the head from the neck is not feasible. The test assesses the 
performance of the head skin and CG accelerometers, which are used to 
calculate HIC15.\152\ The probe force and the head CG 
resultant acceleration are measured and would have to be within the 
proposed acceptance intervals.
---------------------------------------------------------------------------

    \152\ Craig, M., Parent, D., Lee, E., Rudd, R., Takhounts, E., 
Hasija, V. (2020). Injury Criteria for the THOR 50th Male ATD. 
Regulations.gov Docket ID NHTSA-2019-0106-0008, available at: 
https://www.regulations.gov/document/NHTSA-2019-0106-0008.
---------------------------------------------------------------------------

B. Face Impact

    The face qualification test is identical to the face rigid disk 
impact biofidelity assessment, where a fully-assembled THOR-50M is 
seated on a table and impacted on the face with a 13 kg rigid impactor 
with a 152.4 mm diameter flat disk impact surface at 6.73  
0.05 m/s. This test assesses the impact response of the face, which is 
driven primarily by the face foam insert (Part No. 472-1401). 
Additionally, as this test is more severe than the head impact test, it 
assesses the head CG accelerometers (which are used to calculate 
HIC15) at a level of severity closer to that expected from 
vehicle crash tests. FMVSS No. 208 specifies a maximum calculated 
HIC15 value of 700 for the HIII-50M, and the average 
HIC15 measurement from a set of 29 vehicle crash tests in 
either the full frontal rigid barrier or OMDB crash test modes was 
285.\153\ The head impact test, however, results in an average 
HIC15 of 157 (probability of AIS 3+ injury of 0.05%), while 
the face impact is more severe, with an average HIC15 of 
around 450 (probability of AIS 3+ injury of 3.5%). Therefore, compared 
to the head impact test, the face impact test is a better assessment of 
the head response at a severity level expected from vehicle crash 
tests, as it results in a HIC15 that is closer to the 
current FMVSS No. 208 injury assessment reference value. During these 
tests, the probe force and the head center of gravity (CG) resultant 
acceleration are measured and would have to be within the proposed 
response corridors.
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    \153\ The range was 104-1262 and the standard deviation was 210.
---------------------------------------------------------------------------

C. Neck

    The proposed neck qualification test series, in which the entire 
head-neck assembly is removed from the ATD and affixed to the 
conventional Part 572 swinging pendulum to apply a prescribed impulse 
to the neck, includes six tests: flexion, extension, left lateral 
flexion, right lateral flexion, left torsion, and right torsion. The 
swinging pendulum apparatus serves as a surrogate for the more complex 
neck biofidelity assessment, which is carried out in a sled test 
configuration. The neck qualification tests assess the collective 
performance of the molded neck column, the occipital condyle cam and 
associated bump stops, and the neck spring towers. In the process, the 
neck qualification tests assess the performance of the upper neck load 
cell, from which the Z-axis force and Y-axis moment are used to 
calculate Nij.\154\ The neck axial force, neck moment about the 
relevant axis, and neck rotation about the relevant axis are measured 
and would have to be within the proposed acceptance intervals. The neck 
flexion and extension qualification tests are similar to those 
specified for the HIII-50M \155\ in that they use the same pendulum and 
similar deceleration specifications.
---------------------------------------------------------------------------

    \154\ Craig et al (2020), Injury Criteria for the THOR 50th Male 
ATD.
    \155\ 49 CFR 572.33 Neck.
---------------------------------------------------------------------------

D. Upper Thorax

    This test involves impacting the chest of a fully-assembled THOR-
50M seated on a table with a rigid impactor. The upper thorax 
qualification test is configured similarly to that carried out on the 
HIII-50M,\156\ using the same pendulum (23.36 kg, 152.40 mm diameter) 
to impact the mid-sternum, but at a lower impact velocity of 4.3 meters 
per second. This test assesses the dynamic thoracic response to sternal 
impact as well as the functionality of the upper left and upper right 
thoracic deflection instrumentation. This test condition is identical 
to the associated biofidelity assessment, though the qualification test 
uses only internal deflection measurements so that motion tracking or 
other external instrumentation is not required. Several measurements 
must be within the proposed acceptance intervals: the peak overall 
probe force, the peak upper left and upper right resultant deflections, 
the difference between the peak left and right resultant deflections, 
and the probe force at the peak left and right resultant deflections.
---------------------------------------------------------------------------

    \156\ 49 CFR 572.34 Thorax.
---------------------------------------------------------------------------

    In the 2016 qualification procedures, the upper thorax 
qualification required individual X-axis and Z-axis deflection 
specifications for both the upper left and upper right thorax. This was 
revised in the 2018 qualification procedures by specifying the peak 
resultant deflection instead, which better aligns with the peak 
resultant deflection measure used to evaluate thoracic injury 
risk.\157\

[[Page 61921]]

Applying specifications on the resultant deflection instead of two 
individual components allows for a reduction in the overall number of 
required measurements, while still capturing the physical response of 
the dummy since the X-axis and Z-axis deflections are the primary 
components of the resultant deflection in this test condition.
---------------------------------------------------------------------------

    \157\ Craig et al (2020), Injury Criteria for the THOR 50th Male 
ATD.
---------------------------------------------------------------------------

    The Euro NCAP qualification response requirements differ from the 
proposal in three ways. First, they include an additional parameter: 
the ratio of Z-axis to X-axis deflection. Second, they do not require a 
maximum difference between left and right peak resultant deflection, 
whereas the proposed qualification targets limit the left-to-right 
difference to 5 millimeters. Using the Euro NCAP targets, the 
difference between the left and right peak resultant deflections could 
be as high as 7.2 millimeters. Third, as noted above, the qualification 
targets are narrower than the proposed qualification targets.
    NHTSA has tentatively decided not to specify the ratio of Z-axis to 
X-axis deflection because doing so would effectively revert to the 2016 
approach of individual X-axis and Z-axis deflection requirements, which 
would increase the difficulty in meeting the qualification 
specification without a direct link to injury prediction, as the peak 
resultant deflection specification is of primary importance because it 
is the metric used in the calculation of thoracic injury risk.
    NHTSA is aware that the upper thorax qualification specification 
has been a topic of frequent discussion within the International 
Standards Organization (ISO) working groups (particularly ISO/TC 22/SC 
36, Safety and impact testing, Working Groups 5, Anthropomorphic Test 
Devices, and 6, Performance criteria expressed in biomechanical terms). 
NHTSA understands that those discussions have focused on potential 
modifications to the drawing package to meet the upper thorax 
qualification response requirements (in the context of testing related 
to Euro NCAP). Those modifications--specifically, the shorter rib 
guide, the individual rib performance test, and changes in the area of 
the coracoid process--have been discussed as describe in Section III, 
Design, Construction, and Instrumentation.\158\ NHTSA does not believe 
the modifications are necessary to meet the proposed upper thorax 
qualification requirements because NHTSA's repeatability and 
reproducibility testing showed that those requirements were achieved by 
three different THOR-50M units at three different test labs. See 
Section VI, Repeatability and Reproducibility. Moreover, it is not 
clear whether these changes would preclude a THOR-50M from meeting the 
proposed qualification requirements, though since the Euro NCAP 
specifications are narrower, any variation caused by these changes may 
be within the NHTSA's proposed acceptance intervals. Before 
implementing any of these design changes, the performance of the 
prototype parts would need to be evaluated.
---------------------------------------------------------------------------

    \158\ In addition, some members of Working Group 5 have observed 
variations in the ATD responses in the upper thorax qualification 
tests that have led to difficulties in meeting the Euro NCAP 
qualification specifications, and have suggested that this may 
result from variation in the spine flex joint, potentially due to 
material that was not as hard as the specification called for.
---------------------------------------------------------------------------

    In an effort to further investigate these contemplated changes to 
THOR-50M, NHTSA analyzed its upper thorax qualification test data. 
NHTSA's limited analysis suggests that the difficulty meeting the Euro 
NCAP upper thorax qualification requirements might stem not from the 
dummy design, but from the smaller allowable range of peak resultant 
deflection and the addition of the deflection ratio corridor specified 
in TB026. However, it would be necessary to know how the Euro NCAP 
upper thorax qualification requirements were determined to carry out a 
complete analysis. This preliminary analysis is discussed in more 
detail in Appendix A.

E. Lower Thorax

    The lower thorax qualification test is unique to the THOR-50M. This 
test involves impacting the lower thorax of a fully-assembled THOR-50M 
seated on a table with a rigid impactor. It is similar to the upper 
thorax qualification test, as it uses the same pendulum (23.36 kg, 
152.40 mm diameter) at the same impact velocity (4.3 meters per 
second). The test assesses the dynamic impact response of the lower 
torso, to which the rib cage and the upper and lower abdomen assemblies 
contribute, while at the same time assessing the functionality of the 
lower left and upper right thoracic deflection instrumentation. The 
lower thorax qualification test is a simplification of the lower 
ribcage oblique impact biofidelity condition. In the biofidelity 
condition, the torso is rotated by 15 degrees and a chestband is used 
to measure external deflection. In the qualification condition, the 
torso is not rotated, but instead offset relative to the line of travel 
of the pendulum such that the pendulum is centered on the lower left or 
lower right anterior attachment point of the thoracic deflection 
instrumentation. As in the upper thorax condition, the lower thorax 
qualification mode uses internal deflection measurements so that motion 
tracking or other external instrumentation is not required. During this 
test, the peak overall probe force and the peak resultant thoracic 
deflection at the time of peak probe force are measured and would have 
to be within the proposed acceptance intervals.

F. Abdomen

    This test (which is unique to the THOR-50M) impacts the lower 
abdomen of a fully-assembled THOR-50M with a 177.8 mm by 50.8 mm rigid 
rectangular face impactor, weighing 32.00 kg, at 3.30 m/s. It was 
originally based on the lower abdomen rigid bar biofidelity condition, 
though several modifications were made over time to increase its 
objectivity and improve its utility as a qualification test. This test 
assesses the dynamic response of the lower abdomen, including the 
jacket, lower abdomen foam inserts, and lower abdomen bag, as well as 
the functionality of the abdominal deflection instrumentation. The peak 
overall probe force, the peak left and right X-axis abdomen deflection 
at the time of peak probe force, and the difference between the left 
and right X-axis deflection at the time of peak probe force are 
measured and would have to be within the proposed acceptance intervals.

G. Upper Leg

    The upper leg qualification test assesses the dynamic impact 
performance of the knee flesh, knee flesh insert, and femur compression 
element, while evaluating the functionality of the femur and acetabulum 
load cells. The full THOR-50M is seated on a table with a posterior 
restraint adjacent to the pelvis flesh and impacted at the knee by a 
12.00 kg impactor with a 76.2 mm diameter rigid disk impact surface at 
3.3  0.05 m/s parallel to the femur. The peak probe force, 
peak femur Z-axis force, and peak resultant acetabulum force would have 
to be within the proposed acceptance intervals.
    This differs from the test procedure in the 2018 Qualification 
Procedures Manual in the THOR-50M research docket. The 2018 draft 
qualification test procedures for impacting the knee specifies the use 
of a 5.0 kg impactor at 2.6 m/s. NHTSA's repeatability and 
reproducibility testing of the qualification procedures, however--which 
used the 2018 draft procedures--resulted in coefficients of variation

[[Page 61922]]

(CVs) \159\ above 10%, particularly for the peak resultant acetabulum 
force. NHTSA therefore conducted a detailed review of the qualification 
test procedure.\160\ This review led NHTSA to conclude that the impact 
energy was unrealistically low, leading to two problems. First, the low 
test energy did not load the acetabulum at a magnitude similar to that 
produced in vehicle crash tests or associated with a meaningful injury 
risk. This is particularly important because the upper leg test mode is 
the only qualification test that assesses the acetabulum load cells, 
and peak resultant acetabulum force is used in calculating the 
acetabulum injury risk. Second, and relatedly, the measurement values 
were so low, it was difficult to distinguish the signal from the noise.
---------------------------------------------------------------------------

    \159\ See infra Section VI.A.
    \160\ Millis, W. (2021). An Improvement to the THOR-50M Upper 
Leg Qualification Test Methodology. 2021 SAE Government-Industry 
Digital Summit, available at: https://www.nhtsa.gov/node/103666.
---------------------------------------------------------------------------

    Accordingly, NHTSA revised the test parameters by increasing the 
impactor mass and velocity and installing a backer plate behind the 
pelvis to prevent any rearward motion during the test. These are the 
parameters that we are proposing and for which data is presented (and 
acceptance intervals calculated) in the qualification repeatability and 
reproducibility study. As we explain in Section VI.A, the revised test 
procedures resulted in repeatability and reproducibility CVs of 5% or 
lower for all test measurements including peak resultant acetabulum 
force. Additionally, the average acetabulum force recorded in the 
improved upper leg qualification is more representative of the forces 
recorded in frontal rigid barrier and OMDB vehicle crash tests, and 
represents a non-negligible injury risk.

H. Knee and Lower Leg

    NHTSA is also proposing qualification tests for the knee and lower 
leg (ankle, ball of foot, and heel).
    The knee qualification test is a simplification of the knee shear 
biofidelity condition. The test assesses the response of the anterior-
posterior translation of the tibia with respect to the femur at the 
knee joint, the translational resistance of the knee slider and the 
stiffness of the stop assembly, and the functionality of the knee 
slider string potentiometer. To conduct the knee impact test, the left 
or right knee assembly (detached at the base of the femur load cell) is 
removed from the ATD and mounted to a rigid surface, and a load 
distribution bracket is attached to the knee slider assembly. The load 
distribution bracket is impacted with a 12.00 kg impactor with a 76.2 
mm diameter rigid disk impact surface at 2.20  0.05 m/s. 
Unlike the HIII-50M knee slider test, no foam pad is used on the impact 
surface for this test. During these tests, the femur Z-axis force and 
knee slider deflection at peak femur force are measured and would have 
to be within the proposed acceptance intervals.
    We propose four different qualification tests to assess the lower 
leg responses: ankle inversion, ankle eversion, ball of foot impact, 
and heel impact. All four test setups are similar. In each, the lower 
legs are removed from the dummy and each leg is tested separately. The 
leg is affixed to a rigid fixture and struck by a pendulum parallel to 
the tibia. The alignment of the pendulum differs for each test: for the 
heel impact, it is in-line with the tibia; for the ball of foot impact, 
it produces dorsiflexion of the foot; for the inversion impact; it is 
offset medially from the tibia; for the eversion impact, it is offset 
laterally from the tibia. For the inversion and eversion impacts, the 
shoe is removed and replaced with a special striker plate that 
interfaces with the pendulum.
    Euro NCAP TB026 specifies different qualification requirements for 
the knee and lower leg because TB026 specifies that the THOR-50M be 
fitted with the HIII-50M knee and lower leg.

VI. Repeatability and Reproducibility

    Any ATD that is to be used for Federal regulatory testing must have 
an acceptable level of repeatability and reproducibility to ensure 
confidence in the responses provided by the dummy. In the context of 
dummy evaluation, repeatability refers to the similarity of responses 
from a single dummy when repeatedly subjected to a particular test 
condition. Reproducibility refers to the similarity of the responses 
from multiple dummies repeatedly subjected to a particular test 
condition. NHTSA also evaluated the repeatability and reproducibility 
of the qualification tests themselves, in addition to the dummy. To 
evaluate whether the THOR-50M ATD yields consistent results, NHTSA 
undertook an extensive series of testing.
    NHTSA systematically investigated the repeatability and 
reproducibility (R&R) of the THOR-50M by conducting an extensive series 
of qualification and sled tests. Qualification test measurements are 
especially useful for evaluating dummy R&R because they are relatively 
simple tests on individual dummy components that can be tightly 
controlled so that variability in the test measurements is more likely 
to come from the dummy than from other potential sources of 
variability, such as the test procedures or vehicle structures and 
materials. Sled testing is useful because it offers insight into the 
dummy's performance as a complete system in an environment similar to 
that of an actual vehicle--e.g., the consistency of its kinematics, its 
impact response as an assembly, and the integrity of the dummy's 
structure. Sled tests are therefore more challenging for the dummy, 
while at the same time much more tightly controlled than a vehicle 
test, which does not provide a desirable environment for R&R testing 
due to the uncontrollable variation in vehicle structural materials and 
manufacturing variability. Qualification and sled tests together 
provide a basis for assessing whether the dummy will yield consistent 
results when it is ultimately used in full-scale vehicle tests. NHTSA's 
R&R testing also served several other important functions, such as 
developing the qualification corridors and further validating the 
usability and durability of the dummy.
    NHTSA's R&R analysis of qualification and sled testing is briefly 
summarized in the next two sections. For more detailed information, the 
reader is referred to the docketed report ``THOR-50M Repeatability and 
Reproducibility of Qualification Tests'' (R&R Report).\161\
---------------------------------------------------------------------------

    \161\ National Highway Traffic Safety Administration (2022). 
THOR-50M Repeatability and Reproducibility of Qualification Tests, 
May 2021, available at https://downloads.regulations.gov/NHTSA-2019-0106-0009/attachment_2.pdf. We note that for the sled test R&R 
analysis, there are no previously-published reports that provide 
this analysis. However, this analysis is provided in the paragraphs 
below on sled testing (and in the relevant appendices) and the 
underlying data is available in the NHTSA crash test database in 
either the biomechanics or vehicle paragraphs (the specific location 
is provided in the relevant discussion below).
---------------------------------------------------------------------------

    A note about dummy reproducibility: At the time NHTSA conducted 
this R&R testing (both qualification tests and sled tests) it only 
owned--and tested--THOR-50M units manufactured by Humanetics. 
Therefore, the reproducibility analyses reported here concerned dummy 
reproducibility (same lab, different dummies) and test reproducibility 
(same dummy, different labs).\162\ However, another aspect of 
reproducibility is whether dummies fabricated by different 
manufacturers perform in a uniform manner. To this end, NHTSA has 
purchased THOR-50M units from JASTI, Cellbond, and Kistler,

[[Page 61923]]

and may test with these units prior to the final rule.
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    \162\ NHTSA did not examine lab-to-lab reproducibility of the 
sled tests.
---------------------------------------------------------------------------

A. Qualification Tests

    NHTSA has completed an R&R study of the qualification tests. This 
study has three main purposes. One is to assess the repeatability and 
reproducibility of the dummy. Another is to determine the acceptance 
intervals for the qualification tests. Third, is to assess the R&R of 
the qualification tests themselves. Assessing the R&R of the 
qualification tests is important for at least two reasons: it aids in 
determining whether the variation in measurements are attributable to 
the dummy, the test procedures, or the testing practices of different 
laboratories, and it helps ensure that the qualification test 
procedures themselves are as consistent and replicable as possible so 
that, ultimately, the test measurements obtained in a compliance test 
are uniform across dummies and test laboratories. In addition to these 
main purposes, the qualification R&R testing also helped NHTSA to 
identify and resolve potential issues with the qualification 
procedures; reveal and resolve potential issues with, and functional 
limitations of, the dummy.
    Below, we first summarize our methodology for the qualification R&R 
analysis, and then proceed to briefly summarize the results of the R&R 
assessment for each THOR-50M body region.
Methodology
    The proposed qualification tests were carried out on three THOR-50M 
ATDs manufactured by Humanetics. The ATDs conformed to the proposed 
drawing package. Every ATD was subjected to five repeat tests in each 
qualification test condition at NHTSA's Vehicle Research and Test 
Center (VRTC) and one of the three dummies was tested at two other 
labs, Humanetics and Calspan (with some exceptions as described in the 
following paragraphs). All tests were used in development of the 
proposed qualification acceptance intervals, with some exceptions as 
explained below where the input velocity did not meet the 
specification. For qualification test conditions where one ATD 
component is tested in both the left and the right direction, only the 
left direction is included in the analysis, as the dummy design is 
symmetric and not expected to differ between the two sides. For 
qualification test conditions in which multiple ATD components are 
tested, data from the left and right tests or measurements are 
combined.
    We evaluated R&R of both the dummy and the qualification tests 
using a statistical analysis of variance referred to as the coefficient 
of variation (CV). The CV approach was first introduced by NHTSA as a 
means for evaluating dummy repeatability when the original subpart B 
Hybrid II 50th percentile male ATD was proposed.\163\ Since then, the 
agency has used this approach for other Part 572 rulemakings.\164\ The 
CV is a measure of variability expressed as a percentage of the mean. 
It is defined as the percentage of the sample standard deviation 
divided by the mean of the data set:
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    \163\ 40 FR 33466 (Aug. 8, 1975).
    \164\ See, e.g., 85 FR 69898, 69904-69905 (Nov. 3, 2020) (final 
rule for Q3s ATD).
[GRAPHIC] [TIFF OMITTED] TP07SE23.019

    In the qualification test series, the data points of each trial are 
considered on their own and not as being representative of a large 
population. Thus, the sample-based standard deviation is applied in 
which s is an estimate of the standard deviation based on a 
sample.\165\ It is computed using the following formula, where x is the 
average value of the trials (sample mean) and n is the number of trials 
(sample size).
---------------------------------------------------------------------------

    \165\ The population-based standard deviation, which is always 
lower than the sample-based standard deviation, is not appropriate 
because only a limited number of NHTSA-owned THOR-50M units were 
tested, and the tests were carried out at a limited number of test 
facilities.
[GRAPHIC] [TIFF OMITTED] TP07SE23.020

    For each qualification test parameter (e.g., head impact peak probe 
force) specified for each test condition (e.g., head impact), we 
computed the mean, standard deviation, and coefficient of variation. 
More specifically, to investigate dummy repeatability and test 
repeatability, we calculated these summary statistics for the five 
tests of each test condition performed on each of the three dummies at 
VRTC. To investigate dummy reproducibility, we pooled the data for the 
three dummies tested at VRTC. Finally, to investigate test 
reproducibility, we pooled the data for the dummy that was tested at 
VRTC, Calspan, and Humanetics.
    We used the following approach to assess R&R:
     CV <5%: No further investigation. We believe that a set of 
responses with a CV below 5% indicates a highly repeatable and 
reproducible condition.
     5% >= CV <= 10%: sources of variability investigated.
     CV >10%: Test procedure thoroughly reviewed and dummy(ies) 
inspected.
    When the CV was greater than or equal to 5%, we investigated the 
source of the variability. In all cases, we were able to determine the 
source of the variation with reasonable confidence. Once NHTSA had 
refined the qualification test procedures it only obtained a CV greater 
than 10% in two instances--repeatability of the face foam, and test 
reproducibility in one measurement in the neck extension mode. Prior to 
refining the test procedures, NHTSA obtained a CV greater than 10% for 
the upper leg test. A full investigation led to a new and improved test 
procedure. That new test procedure is reflected in the R&R report, and 
the resulting CVs all less than 10%. Table 9 and Table 10 summarize the 
CVs that we calculated for each test parameter for each qualification 
test condition. Table 11 summarizes the variability sources and 
resolutions seen in the qualification R&R test series.
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     Table 11--Summary of Qualification Test Variability Sources and
                               Resolutions
------------------------------------------------------------------------
          Test mode              Source of varibility; control solution
------------------------------------------------------------------------
Head.........................  None.
Face.........................  Face foam degradation occurs cumulatively
                                with successive impacts; monitor and
                                swap out foam as needed.
Neck Extension...............  The inverse relationship between My and
                                Fz may be balanced by adjusting the
                                input pulse through the selection of the
                                pendulum's honeycomb cell configuraton.
Neck Flexion.................  For a new molded neck, My and Fz may be
                                elevated in initial test only. Also, the
                                pendulum's honeycomb cell configuration
                                may need attention to control input
                                pulse.
Neck Lateral.................  None.
Neck Torsion.................  None.
Upper Thorax.................  None.
Lower Thorax.................  The asymmetric test setup requires a high
                                level of diligence from operator in
                                aligning the dummy with the probe.
Abdomen......................  Operator diligence is needed to ensure a
                                symmetric test setup. Otherwise, right
                                vs. left discrepancies in force and
                                deflection measurements will occur.
Upper Leg....................  If a high femur Fz occurs, a test lab may
                                need to experiment with set-ups and
                                dummy positioning (within allowable
                                tolerances).
Knee.........................  Low femur Fz measurements may be resolved
                                at the test labs by experimenting with
                                setups and dummy positioning.
Ankle Inversion..............  Ankle inversion and eversion tests are
Ankle Eversion...............   run on the same apparatus and are nearly
                                identical. The ankle moment, tibia Fz,
                                and ankle rotation may be slightly low
                                in an initial qualification test if
                                there has been an extended period of non-
                                use of the Ensolite pad on the test
                                fixture. This is only a concern if the
                                tibia force and moment are just below
                                the upper qualification limits, since
                                subsequent tests may be expected to
                                produce slightly higher moments and
                                forces (which might be out of the
                                qualification range). Labs can simply
                                perform an additional test to confirm
                                that the response of the ankle is within
                                the requirements.
Ball of Foot.................  Test labs may need to adjust their set-
                                ups and fixtures (within allowable
                                tolerances) to attain a reponse within
                                10% of the target for ankle moment.
Heel.........................  In cases where passing qualification
                                results cannot be achieved, a test lab
                                may need to replace the molded shoe
                                assembly (472-7800-1 (left) or -
                                2(right)) and/or the upper tibia
                                complaint bushing assembly (472-7315) in
                                order to attain a peak lower tibia Fz
                                within 10% of the target.
------------------------------------------------------------------------

    Our investigation of the sources of variability also gives us 
additional confidence that the proposed acceptance intervals ( 10% of the mean response reported in the R&R study) are both 
achievable and sufficient to ensure that the dummy is providing uniform 
responses. In NHTSA's testing, when the CV was below 5%, the responses 
in all the tests were always within the proposed acceptance intervals. 
When the CV exceeded 5%, however, we observed a response outside the 
proposed acceptance interval in at least one test. When the CV exceeded 
10%, several tests were outside the qualification corridor.
    NHTSA seeks comment on this methodology. Although the qualification 
R&R study utilizes only NHTSA's test data, NHTSA is open to considering 
qualification data provided by commenters in the finalization of the 
qualification specifications, provided that the data are from THOR-50M 
ATDs conforming to the 2023 drawing package and collected following the 
proposed Qualification Procedures.
Head Impact
    In the head impact qualification test mode, all CVs for 
repeatability and reproducibility were below 5%, and the responses in 
all the tests were within the proposed qualification acceptance 
intervals.
Face Impact
    We used a slightly different approach to evaluating the R&R of the 
face than we did for the other qualification tests. Our approach was 
motivated by two characteristics of the THOR-50M face.
    First was the response of the face foam. The impact response of the 
face is driven primarily by the face foam insert, which is constructed 
of a memory foam that necessitates an extensive recovery period after a 
dynamic impact; the THOR-50M Qualification Procedures specifies at 
least 24 hours of recovery between tests. Even with this extended 
recovery period, however, the foam progressively degrades after each 
impact so that the peak probe force and peak head resultant 
acceleration increases with each test. We were able to conduct eight to 
nine tests with a new face foam insert before the face fell outside the 
upper bound of the face rigid disc impact biofidelity corridor (4,400 N 
to 8,200 N).
    Second, because the face foam degrades, any variations in the dummy 
response are likely to be masked by the significant variations caused 
by the foam. That is, most of the observed variation in the face 
qualification test is essentially due to the face foam response; any 
contributions of other components or lab-to-lab differences were 
negligible.\166\
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    \166\ This is seen in the head impact test series, in which the 
headskins were found to be repeatable and reproducible, with 
repeated impacts to the head yielding nearly identical responses.
---------------------------------------------------------------------------

    In light of these characteristics, we modified the R&R test 
methodology for the face impact tests. Our testing consisted of 
evaluating one dummy (DO9799) at VRTC, using three different new, 
unused, face foams (as opposed to testing three different ATDs); we 
deemed it unnecessary to test multiple ATDs because the variation in 
response was predominantly due to the face foam, not the ATD. We also 
did not test lab-to-lab variability (test reproducibility), because 
this would require testing the same face foam successively at multiple 
laboratories, which the degradation of the face foam prevented us from 
doing. We allowed 24 hours between tests as specified in the 
Qualifications Procedures. We tested each dummy until the peak probe 
force

[[Page 61930]]

fell out of the biofidelity corridor (until the peak probe force 
exceeded 8,200 N). Only those tests which fell within the peak probe 
force biofidelity corridor were then included in the repeatability 
analysis and used to set the qualification targets. This gave us eight-
to-nine tests for each of the three face foams we tested.
    For two of the face foam inserts tested, repeatability CVs were 
below 10%. The third face foam insert resulted in CVs for peak probe 
force and peak head CG resultant acceleration of 10.1% and 12.1%. 
Though not reported in the R&R paper, CVs for the HIC15 
values associated with the head resultant accelerations recorded in the 
face impact test are within 1% of the CVs for peak resultant head CG 
acceleration. However, in practice, we would likely not observe this 
level of variability because in several of the tests used to calculate 
CV, the peak probe force was outside of the qualification targets 
(either too high or too low) and so the dummy would have been further 
adjusted before being used in a compliance (or research) test. We 
observed that when the response of a new face foam insert is too low, 
it likely indicates the need for an additional ``break in'' test, in 
which case the face impact test would be repeated. If the response is 
too high, it likely indicates that the face foam needs to be replaced, 
in which case a new face foam insert will be installed and the face 
impact test repeated. Therefore, we believe that the face impact test 
is sufficiently repeatable. Moreover, although we did not test at 
multiple labs to evaluate reproducibility due to face foam degradation, 
we also believe that the face impact test is reproducible. The head 
impact test uses essentially the same test apparatus and a similar 
impact condition as the face impact test. Because the test 
reproducibility was very good in the head impact test, we expect that 
there will be acceptable levels of lab-to-lab variability for the face 
impact test as well.
Neck
    For the neck qualification tests, the entire head-neck assembly is 
removed from the THOR-50M, so the serial numbers listed in Table 9 are 
those of the individual head-neck assemblies and not the ATD itself.
    With respect to repeatability, across all four neck test modes 
(flexion, extension, lateral flexion, and torsion), CVs for 
repeatability were below 10% for all qualification test parameters and 
for all necks, and were below 5% except in the neck flexion test mode 
for two of the necks: peak upper neck Y-axis moment (5.8%) and peak 
upper neck Z-axis force (6.0%) for neck EB6007, and peak upper neck Y-
axis moment for neck EB6006 (5.1%). For both of these necks, the first 
test resulted in a peak upper neck Y-axis moment higher than the 
resulting qualification targets; thus this first test would have been 
re-run in practice. If this first test were discarded, the resulting 
repeatability CVs would be at or below 5% for all necks. Labs may find 
that while the first neck flexion test performed on a new neck produces 
a Y-axis moment greater than the qualification targets, subsequent 
tests result in lower values within the acceptance interval. Also, labs 
may need to adjust the input pulse by experimenting with honeycomb cell 
configurations to achieve the target response.
    Reproducibility CVs were below 5%, except in four instances, two 
for the neck flexion test mode, and two for the neck extension test 
mode.
    In the neck flexion test mode, the dummy reproducibility CV for 
peak upper neck Y-axis moment was 5.4%. This likely results from the 
same break-in issue described above. Also in the neck flexion test 
mode, the test reproducibility CV for peak upper neck Z-axis force was 
7.5%. In this case, there were two tests each at Calspan and Humanetics 
that would not have met the resulting qualification 
specifications,\167\ though discarding these tests would still result 
in a reproducibility CV of 6.4% for peak upper neck Z-axis force. 
However, we believe that this variance is not likely to lead to 
inconsistent compliance test outcomes because the average peak upper 
neck Z-axis force (860 N) represents a very low probability of injury 
(0.7% risk of AIS 3+ injury). Although NHTSA has not yet established 
injury assessment reference values (IARVs) for the THOR, when it does 
(NHTSA anticipates rulemaking in the near future to add the THOR-50M to 
FMVSS No. 208 as an optional test device) an IARV for neck flexion 
would almost certainly be specified to correspond to a risk of AIS 3+ 
injury much higher than 0.7%, i.e., corresponding to a much higher Z-
axis force than 860 N.\168\
---------------------------------------------------------------------------

    \167\ R&R Report, Table 6-14.
    \168\ Upper neck Fz is currently specified in FMVSS 
NO. 208 as an injury criterion for the HIII-50M and is also a 
component of THOR-specific Nij criterion.
---------------------------------------------------------------------------

    In the neck extension test mode, two test reproducibility CVs were 
above 5%: peak upper neck Y-axis moment (5.6%) and peak upper neck Z-
axis force (12.2%). These elevated CVs result from the tests on neck 
EB6007 at Calspan, for which the first four tests resulted in peak 
upper neck Z-axis forces lower in magnitude than the resulting 
qualification targets, while the last test resulted in a peak upper 
neck Y-axis moment higher in magnitude than the resulting qualification 
targets, and at Humanetics, for which four of the five tests resulted 
in peak upper neck Z-axis forces higher in magnitude than the 
qualification targets, though by not more than 32 N.\169\ However, 
since all of the remaining tests on neck EB6007 at VRTC (15 tests) 
would have met the qualification targets, and the associated test 
reproducibility CVs would be below 3% for all test parameters except 
for the Calspan observations, this finding likely results from either 
an issue with test execution at Calspan, or an issue specific to neck 
EB6007, such as damage or unintended adjustment of the neck spring 
cables after it was tested at both VRTC and Humanetics.
---------------------------------------------------------------------------

    \169\ R&R Report, Table 7-16.
---------------------------------------------------------------------------

    While the input parameters for the tests conducted on EB6007 were 
all within the qualification specifications, the pendulum velocity at 
20 and 30 milliseconds after T-zero was notably higher at Calspan 
compared to VRTC and Humanetics, which may explain the differences in 
results. As such, it may be worth considering narrower specifications 
on the pendulum velocity input parameters. On the other hand, if the 
differing results at Calspan resulted from issues with the neck itself, 
then the fact that the qualification specifications were not met 
indicates that the qualification tests successfully identified a 
damaged or improperly configured neck.
Upper Thorax
    In the upper thorax qualification test mode, all CVs for 
repeatability and reproducibility were below 5%, which indicates that 
the qualification specifications were achievable by three different 
THOR-50M ATDs and at three different test labs. Further, as all CVs 
were below 3.7%, this indicates that all tests were within the 10% target.
Lower Thorax
    In the lower thorax qualification test mode, all but one of the CVs 
for repeatability were below 5%. One repeatability assessment, peak 
resultant deflection at peak probe force for ATD DO9798, had a CV of 
5.2%. For this ATD, peak resultant deflections on the right side were 
closer to the upper end of the corridor, while those on the left side 
were closer to the lower end of the corridor. CVs for dummy 
reproducibility were below 5%. Test

[[Page 61931]]

reproducibility CVs were slightly above 5%. Here, one of the tests at 
Humanetics would not have met the resulting peak probe force 
qualification specifications, while four of the tests at Calspan would 
not have met the resultant deflection at peak force specification.\170\ 
If the tests that would not fall within the qualification 
specifications were excluded, as would be done in practice, 
reproducibility CVs would be below 5%. Overall, the lower thorax 
qualification specifications were achievable by three different THOR-
50M ATDs and at three different test labs.
---------------------------------------------------------------------------

    \170\ R&R Report, Table 11-9.
---------------------------------------------------------------------------

Abdomen
    When the abdomen qualification repeatability and reproducibility 
testing was conducted, all three THOR-50M ATDs were not available.
    As an alternative, three different abdomen assemblies were tested 
on the same ATD. We believe this modification is acceptable because the 
abdomen foam inserts and the structure of the abdomen bag are 
responsible for a majority of the variation in the lower abdomen 
qualification test, whereas the remainder of the THOR-50M is 
essentially a ballast.
    All of the CVs for repeatability and reproducibility of peak probe 
force were below 5%. All of the CVs for repeatability and 
reproducibility of the peak left and right X-axis deflection at the 
time of peak force were between 5% and 6%. Of these tests, three at 
Calspan resulted in right abdomen X-axis deflections lower in magnitude 
than the qualification specifications. While not included in the CV 
calculation, the difference between left and right X-axis deflection 
measurement highlighted the fact that all tests at VRTC had a positive 
difference of at least 6.8 millimeters, indicating that the magnitude 
of right X-axis deflection was greater than the magnitude of left X-
axis deflection in all tests. The opposite was true at Calspan, where 
three of the tests showed notably higher magnitude deflections on the 
left side. In total, six of the abdomen qualification tests (five at 
VRTC and one at Calspan) were beyond the 8 millimeter difference 
specified by the qualification specifications. Further examination of 
the test setup at VRTC showed that the ATD was consistently rotated 
slightly about the Z-axis, resulting in the right side of the abdomen 
being closer to the probe than the left side, and subsequently 
recording more deflection. The test configuration at VRTC has since 
been corrected. This issue is not expected to introduce variability in 
test results in the future because such tests outside the qualification 
targets would necessitate dummy adjustment and re-running the test. If 
only tests that were within the maximum difference in left-to-right 
deflection specification were included, both the dummy and test 
reproducibility CVs would be 5.0% or below.
Upper Leg
    As we explained earlier (Section VI, Qualification Tests), the 
proposed upper leg qualification test procedure reflects revisions to 
the 2018 Qualification Test Procedures that we made in light of our R&R 
testing. The CVs for repeatability and reproducibility for the revised 
test procedure for all three measurements were at or below 5%, 
demonstrating that the upper leg qualification specifications can be 
met by three different THOR-50M ATDs at three different test labs.
Knee
    For the knee qualification test, all CVs for repeatability were 
below 5%. For dummy reproducibility, CVs were 5.0% and below for both 
measures. For test reproducibility, the CV for knee deflection at peak 
femur Z-axis force was below 5%, while the CV for peak femur Z-axis 
force was 5.9%. This elevated CV appears to result from the tests at 
Calspan, which were all generally lower in magnitude than at VRTC and 
Humanetics, and three of the tests resulted in peak femur Z-axis force 
lower than the qualification specification. As the three tests that 
were outside of the qualification specifications were the first or 
second tests in the series, it is possible that the lower forces 
resulted from misalignment of the load distribution plate or other 
slack in the system that was corrected in the remaining tests. In light 
of this, we believe that the knee qualification repeatability and 
reproducibility test series demonstrated that the qualification 
specifications could be achieved by six different THOR-50M knees at 
three different test labs.
Lower Leg
    As used by VRTC, the lower legs are considered modular, and are 
typically assigned to a THOR-50M on deployment and not necessarily tied 
to a specific THOR-50Ms serial number. As such, the repeatability and 
reproducibility qualification study was carried out by testing three 
different lower legs at VRTC, followed by testing two of those legs at 
both Humanetics and Calspan. This resulted in a total of 15 tests for 
the dummy reproducibility assessment, and 30 tests for the 
reproducibility assessment (although several of the tests at Calspan 
were not included because they did not meet the test velocity input 
specifications).
    For all the lower leg test modes, repeatability CVs were all below 
5%, indicating that the qualification specifications are achievable by 
three different THOR-50M ATDs. There were, however, a few test mode/
parameters for which reproducibility CVs were above 5%.
    In the ankle inversion test mode, test reproducibility for the peak 
lower tibia Z-axis force measurement was 5.3%. The source of this 
elevated CV appears to be the first test of leg DL5405 at VRTC, where 
the peak lower tibia Z-axis force was -451 N, which was just outside 
the acceptance interval (-454 to -555 N). In practice, this test would 
have been re-run, and all the remaining tests on this leg would have 
met the qualification targets. Removing this test from the CV 
calculation would result in a test reproducibility CV of 4.9%.
    In the ankle eversion test mode, dummy reproducibility was above 5% 
for the peak lower tibia Z-axis force (5.7%), and test reproducibility 
was above 5% for lower tibia Z-axis force (6.0%) and peak ankle 
resistive moment (5.1%). These elevated CVs appear to result from the 
first tests on DL0202 at VRTC, where the peak lower tibia Z-axis force 
(-512 N) was just outside the acceptance interval (-514 N to -629 N), 
and at Calspan, where the peak lower tibia Z-axis force (-454 N) and 
the peak angle resistive moment (35.6 Nm) were both below the lower end 
of the associated qualification specifications (-514 N and 38.7 Nm, 
respectively). In practice, these tests would have been re-run, and all 
the remaining tests on this leg at both labs would have met the 
qualification specification. Removing these two tests from the CV 
calculation would result in reproducibility CVs all below 5%, which 
demonstrates that the ankle eversion qualification specifications can 
be met by six different legs at three different test labs.
    In the ball-of-foot test mode, which assesses both the impact 
response of the ball-of-foot portion of the molded shoe and the 
dorsiflexion response of the ankle, the only CV above 5% was the test 
reproducibility of the peak ankle resistive moment (6.9%). In the tests 
at Calspan, only two of the five tests on the left leg (DL0202) met the 
qualification specification for input velocity. The three tests that 
did not meet the qualification specification were considered invalid 
tests and therefore were not included in the test

[[Page 61932]]

reproducibility assessment, so only seven tests from Calspan were 
included as opposed to 10 tests from each of the other labs. Of the 
tests run by Calspan on the right leg (DL5404), four of the five 
resulted in peak ankle resistive moments of 61.3 to 61.8 Nm, just above 
the upper end of the qualification specification (60.8 Nm). As the 
tests at Calspan were consistently higher in peak ankle resistive 
moment than those at VRTC and Humanetics, it is possible that this 
finding results from either an issue with test execution at Calspan, or 
an issue specific to leg DL5404, such as damage or unintended 
adjustment of the Achilles spring cables after it was tested at both 
VRTC and Humanetics. Reviewing the time-history data for ankle 
resistive moment from exemplar tests from Calspan, VRTC, and Humanetics 
(Figure 1), there are some differences early in the event (note the 
large positive moment before 10 milliseconds in the Calspan test) that 
suggest differences in test setup and/or impactor hardware.
[GRAPHIC] [TIFF OMITTED] TP07SE23.028

    In the heel impact test, which assesses both the impact response of 
the heel portion of the molded shoe and the tibia compliant element, 
the repeatability CVs were all under 5%, but both the dummy (6.4%) and 
test (5.9%) reproducibility CVs were over 5%. If the test CVs are 
calculated independently for the left and right legs, the resulting CVs 
are much lower (2.1% and 3.0%, respectively). This suggests that the 
test itself is repeatable (as all repeatability CVs were 1.6% or below) 
and reproducible, but that there is some ATD-to-ATD (in this case, leg-
to-leg) variation. Nonetheless, the qualification specifications for 
the heel impact test can be met using three different legs in at least 
two different test labs.
Additional Qualification Test Lab
    We performed a variety of vehicle tests (discussed in Section VIII, 
Overall Usability and Performance) where multiple dummies were 
qualified at two different labs, including a lab (Applus+ IDIADA KARCO 
Engineering LLC) that was not one of the laboratories used to develop 
the qualification specifications, and it was possible to qualify the 
dummies. This qualitative information gives us further confidence that 
the qualification tests are reproducible. Therefore, NHTSA tentatively 
concludes that there is a sufficiently high degree of uniformity in the 
construction of the dummy components being tested and in the procedures 
followed by the labs for that test requirement for the THOR-50M to be 
incorporated into Part 572.

B. Sled Tests

    THOR-50M repeatability was also assessed through sled tests 
representing several different vehicle crash environments, including 
unbelted, standard, and load-limited three-point belt configurations at 
different speeds for both the driver and right front passenger seating 
positions, as well as several restraint configurations in the rear 
seat. NHTSA's sled test repeatability analysis is based on data from 
three different sled test series that NHTSA ran in the course of 
developing THOR-50M. One is a sled test series conducted to develop 
thoracic injury criteria for the THOR-50M. Another is a sled test 
series conducted to assess the performance of THOR-50M in low-speed 
belted crashes. The third is a sled test series conducted to assess 
THOR-50M's performance in low-speed unbelted crashes.
    In summary, while there were several cases where the variation from 
test to test of the same THOR-50M ATD was greater than 10%, these cases 
can be explained by either differences in physical interactions (e.g., 
contact of the head with the arm in the rear seat sled test), which can 
be addressed by careful pre-test positioning of the ATD, or by the low 
magnitude of the measurements, as demonstrated through the use of 
normalized CV to identify cases where the variation occurs at a much 
lower level than would be associated with a risk of injury.
    This is discussed in more detail in the sections that follow. We 
begin by explaining our methodology, and then proceed to discuss the 
three different test series.
1. Methodology
    As with the qualification R&R analysis, we assessed repeatability 
using the coefficient of variation. The CVs were calculated for each of 
the injury criteria described in the THOR-50M injury criteria report, 
as well as for peak

[[Page 61933]]

values from a few other key data channels: \171\ lap belt, upper 
shoulder belt, and lower shoulder belt.
---------------------------------------------------------------------------

    \171\ The low-speed sled tests have fewer metrics than the 
thoracic injury criteria set (11 vs. 12) because lower shoulder belt 
loads were not recorded in the low-speed sled tests.
---------------------------------------------------------------------------

    The CV analysis was the same as in the qualification test R&R 
study, with two modifications. As with the qualification test R&R 
study, CVs below 5% were considered to require no further 
investigation; for CVs between 5% and 10% we reviewed the results for 
outliers; and for CVs greater than 10% we thoroughly investigated the 
sources of variability in the test procedure and the ATD. However, our 
assessment differed in two ways from the CV assessment in the 
qualification R&R study.
    First, we used the population standard deviation instead of the 
sample standard deviation to calculate the CV because these test series 
are the only sled test series that have been run.\172\ Accordingly,
---------------------------------------------------------------------------

    \172\ This differs from the qualification tests, for which it is 
known that the data set is a sample of a larger population (because 
NHTSA and other test labs have run the qualification tests on other 
THOR-50M ATDs).
[GRAPHIC] [TIFF OMITTED] TP07SE23.029

    Second, in addition to the CVs we also considered the normalized 
CVs. A potential limitation of the CV calculation is that when the 
magnitude of a given measurement is relatively low, as is the case with 
off-axis sensor channels, the standard deviation can be high relative 
to the mean, leading to CVs over 10%. However, this result is not 
necessarily meaningful: although the amount of variation might be high 
relative to the mean, it might not be high with respect to say, a 
critical value of the measurement being evaluated (e.g., in the context 
of a compliance test involving an ATD, it might not be high with 
respect to the IARV). This was generally not an issue in the 
qualification test R&R analysis because the qualification modes, test 
parameters, and targets were all selected because they are meaningful 
to the test mode and/or are in the primary load path, so that the 
resulting measurements were generally of sufficient magnitude for a 
reliable CV calculation. In sled and vehicle crash tests, on the other 
hand, it is not known in advance which sensor channels will be of 
sufficient magnitude for a reliable CV assessment. For this reason, 
researchers often disregard high CV values when the magnitude of the 
measurement is relatively low. However, determining the level of the 
measurement below which CV is not reliable is inherently subjective.
    Accordingly, for CVs above 10% we also considered normalized CVs. 
To calculate normalized CV, the mean ([mu]) in the CV calculation (Eqn. 
1) is replaced with a meaningful, pre-determined reference value. Such 
a reference value could be an IARV or a measurement value that 
corresponds to an injury risk similar to the risk that would correspond 
to an IARV. Because IARVs for the THOR-50M have not yet been finalized, 
in most cases we calculated the normalized CV using the value 
associated with a 50% risk of AIS 3+ (above the pelvis) or AIS 2+ 
(below the pelvis) injury as the reference value.\173\ However, there 
is not a known risk function that relates belt forces to risk of 
injury, so for this metric we normalized using the average shoulder 
belt force from the thoracic injury criteria development data set, for 
which just over 50% of the subjects sustained AIS 3+ thoracic injuries 
(a denominator of 5,000 N).\174\ The normalization denominators used 
for each of the measurements are shown in Table 12.
---------------------------------------------------------------------------

    \173\ Fifty percent risk of a given injury severity is a widely-
used tolerance level in ATD research. IARVs specified in the FMVSS 
may or may not correspond to a 50% risk.
    \174\ We used the shoulder belt force to normalize the lap belt 
force because there was not meaningful lap belt force data in some 
of the thoracic injury criteria development test conditions.

                      Table 12--Normalization Denominators for Calculation of Normalized CV
----------------------------------------------------------------------------------------------------------------
                 Metric                           Normalization factor               Normalization rationale
----------------------------------------------------------------------------------------------------------------
HIC15...................................  1724................................  50% risk of AIS 3+ injury.
BrIC....................................  0.96................................
Neck Tension............................  4,662 N.............................  50% risk of AIS 3+ injury when
                                                                                 used in Nij risk function.
Neck Compression........................  -5,017 N............................
Nij.....................................  1.11................................  50% risk of AIS 3+ injury.
Chest Peak Res. Defl....................  51.4 mm.............................
Left Femur Axial Force..................  10,577 N............................  50% risk of AIS 2+ injury.
Right Femur Axial Force.................  10,577 N............................
Peak Femur Axial Force..................  10,577 N............................
Lap Belt Force..........................  5,000 N.............................  Average from thoracic injury
                                                                                 criteria development data set.
Upper Shoulder Belt Force...............  5,000 N.............................
Lower Shoulder Belt Force...............  5,000 N.............................
----------------------------------------------------------------------------------------------------------------

    As an example, consider a repeated test with peak femur forces of 
500 N, 1,000 N, and 1,500 N. For these tests, the calculated CV would 
be 41% (standard deviation of 408 N divided by average of 1000 N), 
which would require a thorough investigation of the test procedure and 
ATD. However, these femur forces are all well below 10,577 N, the force 
at which 50% risk of AIS 2+ injury occurs. Thus, calculating a 
normalized CV may provide a more meaningful assessment. In this case, 
the normalized CV would be 4% (standard deviation of 408 N divided by 
50% risk of AIS 2+ injury of 10,577 N), which would require no further 
investigation.
2. Thoracic Injury Criteria Development Sled Tests
    One source of data NHTSA looked at to further assess repeatability 
is a sled test series conducted to develop thoracic injury criteria for 
the THOR-50M. This involved conducting matched-pair tests of PMHS and a 
THOR-50M ATD in a variety of sled

[[Page 61934]]

test conditions.\175\ This series tested the same THOR-50M unit in 
three to four repeat tests in each of six different test conditions: 
Gold Standard 1, 2, and 3; Rear Standard; Rear Load-limited (Rear LL); 
and Rear Inflatable (Table 13).\176\
---------------------------------------------------------------------------

    \175\ Craig, M., Parent, D., Lee, E., Rudd, R., Takhounts, E., 
Hasija, V. (2020). Injury Criteria for the THOR 50th Male ATD. 
Docket ID NHTSA-2019-0106-0008, available at: https://www.regulations.gov/document/NHTSA-2019-0106-0008.
    \176\ Our testing included a seventh test condition: Far-Side 
Oblique (representing the right front passenger in an oblique moving 
deformable barrier crash test). The THOR-50M setup and positioning, 
however, differed in each of these tests. These tests were not valid 
for the purposes of the repeatability analysis, because the 
differences in setup and positioning is expected to--and in fact 
did--lead to a wider variation in results. Specifically, the CVs for 
8 of the 15 measurements exceeded 10%, with most of these over 20%, 
and some as high as 72%.

                       Table 13--THOR-50M Thoracic Injury Criteria Development Test Matrix
----------------------------------------------------------------------------------------------------------------
                                                              Nominal test
                   TSTNO                         TSTREF       speed  (km/h)    Test condition name, description
----------------------------------------------------------------------------------------------------------------
11117......................................           S0156              40  Gold Standard 1: flat rigid seat,
11118......................................           S0157                   standard lap and shoulder belts,
11119......................................           S0158                   knees restrained, right front
                                                                              passenger restraint geometry.
11120......................................           S0159              30  Gold Standard 2: flat rigid seat,
11121......................................           S0160                   force-limited shoulder belt and
11122......................................           S0161                   standard lap belt, knees
                                                                              restrained, right front passenger
                                                                              restraint geometry..
11514......................................        UVAS0309              30  Gold Standard 3: flat rigid seat
11515......................................        UVAS0310                   angled 30 degrees
11516......................................        UVAS0311                   counterclockwise, force-limited
11517......................................        UVAS0312                   shoulder belt and standard lap
                                                                              belt, knees restrained, right
                                                                              front passenger restraint
                                                                              geometry.
11143......................................           S0199              48  Rear Standard: rear passenger in
11144......................................           S0200                   2004 Ford Taurus buck; 3-point
11145......................................           S0201                   standard belt.
11140......................................           S0196              48  Rear LL: rear passenger in 2004
11141......................................           S0197                   Ford Taurus buck; 3-point load-
11142......................................           S0198                   limited belt with pretensioner.
11137......................................           S0193              48  Rear Inflatable: rear passenger in
11138......................................           S0194                   2004 Ford Taurus buck; 3-point
11139......................................           S0195                   inflatable force-limited belt with
                                                                              pretensioner.
----------------------------------------------------------------------------------------------------------------
Notes: All tests were on THOR-50M S/N 9207. These tests are available in the NHTSA biomechanics database.

    We calculated CVs and normalized CVs for each of the injury 
criteria described in the THOR-50M injury criteria report, as well as a 
few other key data channels, for a total of 12 metrics for each of the 
six test conditions. See Table 14 (CVs) and Table 12 (normalization 
denominators). Sixty-five of the seventy-two CVs calculated were below 
10%, while seven CVs were 10% or above.
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    We believe that this data supports our tentative conclusion that 
the THOR-50M is sufficiently objective for inclusion in Part 572. 
Almost all the CVs were below 10%, and many were at or below 5%. For 
the seven CVs at or above 10%, we believe that these do not indicate 
that the dummy does not yield repeatable results. These seven 
measurements with CVs above 10% were: Gold Standard 1 condition for 
neck compression, Nij, and lap belt load; rear-seat standard belt 
condition neck tension; rear-seat load-limited condition for BrIC and 
neck compression; and rear-seat inflatable belt condition for 
HIC15). When normalized, however, none of these CVs were 
above 10%. This suggests that the variability in these measurements 
would not likely lead to variability in actual testing outcomes. The 
variability in these measurements is much lower than the magnitudes of 
these measurements that would be used as an IARV specified in FMVSS No. 
208.
    For instance, the individual measurements for neck compression in 
the Gold Standard 1 tests were -394 N, -427 N, and -328 N. These have 
an average of -383 N and a standard deviation of 41 N, resulting in an 
unadjusted CV of 11%. While this is greater than 10%--potentially 
suggesting that the source of this variability needs investigation--
these measurements are all much lower in

[[Page 61936]]

magnitude than the compression force that would result in a 50% risk of 
AIS 3+ injury (-5017 N). When the standard deviation is compared to 
this compression force instead of the average neck compression, we 
obtain a normalized CV of 0.8%. This suggests that the magnitudes of 
the neck compression measurements are low compared to the magnitude of 
compression that corresponds to a meaningful injury risk.
    There was one measurement for which the unadjusted CV was below 10% 
but the normalized CV was above 10%: the peak lap belt force in the 
rear-seat inflatable belt condition, which had a normalized CV of 
11.7%. In this instance, the average lap belt load (6,701 N) was higher 
than the normalizing denominator (5,000 N), resulting in an inflated 
normalized CV. As stated earlier, there is not a known risk function 
that relates belt forces to risk of injury, so this elevated normalized 
CV is not of particular concern.
    Otherwise, the highest normalized CV occurred in the BrIC 
measurement in the rear seat load-limited and pretensioned condition 
(9.6%). This appears to result from inconsistent initial positioning of 
the left arm, which is more of a test procedure concern than a THOR-50M 
concern.
3. Low-Speed Belted Sled Tests
    Another source of data NHTSA looked at to assess repeatability is a 
sled test series conducted to assess the performance of THOR-50M in 
low-speed belted conditions. These tests were based on the rigid 
barrier, perpendicular impact belted crash test specified in FMVSS No. 
208 for the HIII-50M. Sled tests were conducted at crash pulses 
representing three frontal rigid barrier impact velocities (24, 32, and 
40 km/h) (15, 20, and 25 mph). This range of speeds was selected 
because FMVSS No. 208 specifies a speed of up to 56 km/h (35 mph) for 
this crash test, and air bag deployment thresholds are typically around 
24 km/h (15 mph); we spanned the 24-40 km/h (15-25 mph) range and 
selected a mid-point of 32 km/h (20 mph) to conduct a crash test and 
get a crash pulse. In each test, the THOR-50M was seated in either the 
driver or right front passenger seating locations of a buck 
representing a mid-sized passenger car.\177\ Three tests were conducted 
at each impact velocity, for a total of 9 tests. The test buck was 
created from an actual vehicle, and included seat belts, front air 
bags, knee-bolsters, and pretensioners. The test matrix and additional 
information about the test setup is provided in Appendix D.
---------------------------------------------------------------------------

    \177\ A HIII-50M was seated in the other front outboard seat.
---------------------------------------------------------------------------

    As with the thoracic injury criteria development test series, both 
CVs and normalized CVs (Table 15) were calculated for each of the 
relevant injury metrics described in the THOR-50M Injury Criteria 
Report, as well as femur and seat belt loads, for 11 metrics for each 
of the six test conditions. Of these 66 CVs, 31 were under 5%, 17 were 
between 5% and 10%, and 18 were above 10%.
    We believe that this data supports our tentative conclusion that 
THOR-50M is sufficiently objective to include in Part 572. Most of the 
CVs were under 10% and many were under 5%. None of the 18 measurements 
for which the CV was above 10% had a normalized CV over 10%, and only 
five were above 5%. This is not surprising, as the low-speed belted 
test condition presents a low likelihood of injury. Thus, while there 
may be variations in the injury metrics, these variations are small 
relative to the values that would represent a meaningful injury risk.
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[GRAPHIC] [TIFF OMITTED] TP07SE23.031

4. Low-Speed Unbelted Sled Tests
    Another source of data NHTSA looked at to assess repeatability is a 
sled test series conducted to assess the performance of THOR-50M in a 
low-speed unbelted condition. Sled tests were conducted at crash pulses 
representing two frontal rigid barrier impact velocities, 32 km/h (20 
mph) and 40 km/h (25 mph), with the THOR-50M in both the driver and 
right front passenger seating locations of a test buck. Three tests 
were conducted at each impact velocity. The test buck was identical to 
that used in the low-speed belted tests except for some minor 
modifications. The test matrix and additional information about the 
test setup is provided in Appendix E.

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    As with the thoracic injury criteria development and belted test 
series, CVs and normalized CVs were calculated for each of the relevant 
injury metrics described in the THOR-50M Injury Criteria Report, as 
well as femur loads, for nine metrics for each of the two crash pulses. 
Of these 36 CVs, 12 were less than 5%, 20 were between 5% and 10%, and 
four were above 10% (Table 16).
    We believe this supports our tentative conclusion that the THOR-50M 
is objective. Almost all the CVs were under 10%, and many were under 
5%. Three of the four measurements with a CV over 10% had a normalized 
CV under 10% (neck tension for driver 32 km/h and RFP 40km/h, and 
HIC15 for RFP 40 km/h), suggesting that the variation is 
small relative to the values that would represent a meaningful injury 
risk. The low magnitudes of neck tension occur because there is no 
torso restraint in these unbelted tests, so that the tension force 
acting on the neck due to the deceleration of the torso is minimal 
(below 500 N). The HIC15 measurements were relatively low 
because the frontal air bags minimized the contact of the head with 
hard surfaces or at least decelerated the head before contact. The 
highest average HIC15 (360) occurred in the right front 
passenger 40 km/h condition, where individual measurements of 309, 349, 
and 423 resulted in a standard deviation of 47.3 and a CV of 13.1.
    Only one of those four measurements that had a CV over 10% also had 
a normalized CV over 10% (BrIC in the Driver 40 km/h condition, 14%). 
NHTSA's analysis of the test procedure and ATD revealed that the 
variation in this case appears to result from a difference in head 
interaction with the sun visor and underlying roof structure, brought 
about by small differences in the timing and/or position of the head at 
the time of contact. This variation could be brought on by initial 
position differences, differences in interaction of the pelvis and 
thighs with the seat cushion during initial forward translation, or 
differences in knee interaction with the knee bolster and/or knee 
bolster air bag. For additional information on this analysis, see 
Appendix E.
    There was one measurement with a relatively low CV, but an 
associated normalized CV above 10%. This occurred for the Nij 
measurement in the

[[Page 61939]]

driver 40 km/h condition, where the CV was 4.7% and the normalized CV 
was 10.7%. Because we normalized by the value of Nij associated with a 
50% injury risk, this indicates that the average value of Nij from the 
three tests in the driver 40 km/h condition were above an Nij 
associated with 50% risk of injury. Closer inspection of the data 
revealed several peaks that cannot be explained by the interaction of 
the dummy with the restraint system and vehicle interior. This suggests 
possible damage to a load cell or cabling. For additional information 
on this analysis, see Appendix E.

VII. Overall Usability and Performance

    NHTSA's extensive testing with the THOR-50M has also enabled it to 
assess THOR-50M's overall usability and performance. This includes 
durability, ease and frequency of maintenance, and how the ATD fits and 
responds in the vehicle environment. We discuss these issues in the 
sections that follow.

A. Assembly and Qualification

    Based on NHTSA's experience with the dummy at VRTC, assembling the 
THOR-50M following the instructions in the PADI takes roughly 80 hours, 
as detailed in Table 17.
    We note that NHTSA treats its THOR-50M units not so much as a 
serialized dummy, but as a set of serialized parts and sub-assemblies. 
NHTSA's THOR-50M units typically undergo a routine breakdown and 
inspection after each application; when the dummy is reassembled, 
different parts may be introduced (for example, if a part needed to be 
refurbished before it could be used again). In addition, parts or sub-
assemblies may be taken out of service at regular intervals and set 
aside to await preventative maintenance. For example, a head and neck 
sub-assembly (both of which are serialized) may be taken out of service 
at regular intervals and set aside to await preventative maintenance; 
once clear, the head and neck sub-assembly may end up in another 
serialized dummy. Therefore, a serialized dummy does not typically 
define the dummy well because different parts are constantly being 
interchanged. The parts and assemblies which are serialized, either by 
the manufacturer or by NHTSA upon delivery of a new ATD or part, are 
listed in Appendix C.

Table 17--Estimated Time To Carry Out Assembly and Associated Procedures
                     Described in the THOR-50M PADI
------------------------------------------------------------------------
                           PADI assembly time
-------------------------------------------------------------------------
                                                                  Time
                   Body region or procedure                      (hrs)
------------------------------------------------------------------------
Head.........................................................          4
Neck.........................................................          8
Spine........................................................          4
Thorax.......................................................          8
Shoulder.....................................................          4
Upper Abdomen................................................          4
Lower Abdomen................................................          4
Pelvis.......................................................          8
Upper Leg....................................................          4
Lower Extremity..............................................          8
Arm..........................................................          4
Jacket and Clothing..........................................          4
Bundling Cables..............................................          4
Polarity Check...............................................          4
Documentation................................................          8
                                                              ----------
    Total....................................................         80
------------------------------------------------------------------------

    Based on NHTSA's experience at VRTC, a complete qualification test 
series of 24 tests takes roughly 80 hours, assuming that the 
qualification specifications are met (Table 18). If the qualification 
specifications are not met, it may take additional time to inspect, 
replace parts where necessary, and re-test. Table 19 describes the 
equipment required to carry out the THOR-50M qualification tests, along 
with the associated setup procedures. Some of this equipment is the 
same or similar to the equipment required for qualification of ATDs 
currently defined in Part 572. For example, the THOR-50M qualification 
procedures for the neck and the upper thorax use the same equipment as 
used in qualification of the HIII-50M. For equipment not currently 
defined in Part 572, the necessary drawings are included in the THOR-
50M drawing package with two exceptions: the impactors for the face 
qualification test and upper leg and knee qualification tests. We 
believe that existing impactors (such as the knee impact probe for the 
HIII-5F \178\) can be modified or ballasted to achieve the required 
mass.
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    \178\ 49 CFR 572.137(b).
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                              Table 19--Equipment Required for Qualification Tests
----------------------------------------------------------------------------------------------------------------
   Test fixture description  [0.02 kg, 0.25 mm]            Reference              Section(s)               Title
----------------------------------------------------------------------------------------------------------------
Rigid disk impactor 23.36 kg, 152.4 mm   CFR Title 49, Sec.                   4, 7, 8  Head, Upper Thorax, Lower
 diameter disk.                           572.36(a); DL500-325.                         Thorax.
Rigid disk impactor 13.0 kg, 152.4 mm    THOR-50M Qualification                     5  Face.
 diameter disk.                           Procedures, Section 5.2.
Neck pendulum..........................  Figure A-2; CFR Title 49,     6.6, 6.7, 6.8,  Neck Torsion, Neck
                                          Sec.   572.33(c)3.                      6.9   Frontal Flexion, Neck
                                                                                        Extension, Neck Lateral
                                                                                        Flexion.
THOR neck twist fixture................  DL472-1000...............                6.6  Neck Torsion.
Lower abdomen probe face assembly......  DL472-3000...............                  9  Abdomen.
Rigid disk impactor 12.0 kg, 76.2 mm     THOR-50M Qualification                    11  Upper Leg, Knee.
 diameter disk.                           Procedures, Section 11.2.
Dynamic impactor.......................  TLX-9000-013.............         12, 13, 14  Ankle Inversion and
                                                                                        Eversion, Ball of Foot,
                                                                                        Heel.
External positioning bracket...........  TLX-9000-016M............             12, 14  Ankle Inversion and
                                                                                        Eversion, Heel.
Dynamic inversion/eversion bracket.....  TLX-9000-015.............                 12  Ankle Inversion and
                                                                                        Eversion.
Lower leg mounting bracket assembly....  DL472-4100...............             12, 13  Ankle Inversion and
                                                                                        Eversion, Ball of Foot
Lower leg zero bracket.................  DL472-3500...............                3.4  Ankle Rotary
                                                                                        Potentiometer Zeroing
                                                                                        Procedure.
Achilles fixture complete assembly.....  DL472-4000...............                3.5  Achilles Cable Adjustment
                                                                                        Procedure.
Load cell mounting assembly............  DL472-4200...............                3.5  Achilles Cable Adjustment
                                                                                        Procedure.
Knee slider load distribution bracket    DL472-5000...............                 11  Knee.
 assembly.
Tibia adaptor..........................  DL472-4300...............                 14  Heel.
----------------------------------------------------------------------------------------------------------------

B. Durability and Maintenance

    In previous sections of the NPRM, we have discussed NHTSA's 
biofidelity testing, qualification testing, and sled tests. In this 
testing, we generally observed that THOR-50M stood up well during 
testing and required maintenance consistent with existing Part 572 
ATDs. In addition to that testing, NHTSA has conducted a variety of 
other tests over the last several years as development of THOR-50M has 
progressed. With respect to evaluating THOR's durability and 
maintenance needs, three series of tests are especially useful because 
they subject the THOR-50M to more severe or challenging crashes: 
elevated energy qualification tests; OMDB testing; and unbelted FMVSS 
No. 208 tests. We discuss this testing in the sections that follow.
1. Elevated Energy Qualification Test Series
    In order to assess THOR-50M's durability, NHTSA conducted an 
additional series of qualification tests at elevated energy levels (for 
example, impactor velocities that exceeded the levels specified in the 
qualification test procedures).\179\ A series of five tests was 
conducted for each of the qualification test modes (except, as 
explained below, the abdomen). The first test in each set was a 
baseline test performed according to the qualification, except that if 
the response measurement did not either represent at least a 50% risk 
of injury or have a magnitude greater than the mean plus one standard 
deviation of the same measurement in a set of 18 oblique vehicle crash 
tests,\180\ the test speed was increased until either of those targets 
were met; this was then considered the baseline speed. There were two 
test modes where the test speed specified in the qualification 
procedures did not reach either of these targets: upper leg impact and 
heel impact.\181\ The next three tests were at speeds corresponding to 
energy level increases of 10 percent, 20 percent, and 30 percent. A 
final baseline test was then performed at the prescribed qualification 
test velocity. The results were considered to show acceptable 
durability if the final baseline test demonstrated a response similar 
to the initial baseline test and within the qualification targets, and 
visual inspection revealed no damage to any of the dummy components. 
For a majority of the qualification test modes, durability was found to 
be acceptable. No visible damage was observed in any of the tested 
components after the series of five tests. Two exceptions to these 
findings occurred in the face and the abdomen qualification test modes.
---------------------------------------------------------------------------

    \179\ National Highway Traffic Safety Administration (2020). 
THOR-50M Durability Report. Regulations.gov Docket ID NHTSA-2019-
0106-0003, available at: https://www.regulations.gov/document/NHTSA-2019-0106-0003.
    \180\ Saunders, J., Parent, D., Ames, E., 2015. NHTSA oblique 
crash test results: vehicle performance and occupant injury risk 
assessment in vehicles with small overlap countermeasures. In: 
Proceedings of the 24th International Technical Conference for the 
Enhanced Safety of Vehicles (No. 15-0108). Available at https://downloads.regulations.gov/NHTSA-2019-0106-0008/attachment_1.pdf.
    \181\ The increase in energy of the upper leg impact test was 
later implemented in the revised qualification procedure.
---------------------------------------------------------------------------

    In the face impact test, the final baseline peak probe force and 
peak head CG resultant acceleration were higher than the qualification 
specifications. This is consistent with the results of the 
qualification R&R study (Section VI.A). While not ideal, we believe 
that, because this is now a known issue, it can be managed with the 
replacement of a face foam insert when the face qualification test 
results are higher in magnitude than the qualification specification. 
Moreover, the deterioration in the face foam insert probably would not 
meaningfully affect crash test results because, in a vehicle test, more 
energy will likely be absorbed by a vehicle interior component and/or 
restraint system compared to the rigid qualification impact probe. 
However, NHTSA would consider specifying a different face foam material 
or design that had improved durability, as long as the material or 
design does not introduce unintended consequences such as negatively 
impacting biofidelity, changes to the inertial properties of the head, 
degradation of repeatability and reproducibility, overall usability, or 
other concerns.
    We did not conduct elevated-energy tests for the abdomen because 
the qualification test already demonstrates a higher energy condition 
than a vehicle crash test. Accordingly, impacts at a

[[Page 61942]]

higher energy level could cause damage due to exhausting the stroke of 
the abdomen instrumentation. Moreover, this would not be meaningful as 
it would represent a loading condition not representative of the front 
seat vehicle crash test environment. However, we do recognize that our 
testing has shown that damage to the abdomen deflection instrumentation 
can occur in vehicle crash test environments where submarining is 
possible, such as reclined rear seats. For example, several rear seat 
sled tests were conducted at VRTC in 2015 in which the IR-TRACCs 
installed in the abdomen experienced dislodged internal retaining rings 
and damage including pinched cables. These issues are believed to have 
resulted from interaction of the IR-TRACC tubes with the foam inserts 
inside of the lower abdomen bag. To address this, the lower abdomen 
sewing assembly (472-4763) was redesigned in late 2015, and an 
inspection procedure was added to the drawing package (472-8320) to 
ensure that the lower abdomen foam inserts remain aligned once 
installed in the assembled lower abdomen bag.
    We seek comment on these issues, especially on alternative 
equivalent face foams.
2. Oblique OMDB Test Series
    In developing THOR-50M, NHTSA ran a series of full-vehicle oblique 
tests with a moving deformable test barrier (OMDB).\182\ Three crash 
tests were conducted on the same make/model vehicle (a 2016 Mazda CX-5) 
at three different test facilities. ATDs were seated in both front 
outboard seats and were fully qualified. Two THOR-50M ATDs were 
successfully implemented in a total of nine vehicle crash tests, with 
qualification tests before and after each set of three tests. In this 
test condition, there were no signs of damage beyond normal wear and 
tear, and there were no sensor failures that were critical to the 
calculation of injury risk. The dummies were inspected after each test.
---------------------------------------------------------------------------

    \182\ Saunders, J., & Parent, D. (2018). Repeatability and 
reproducibility of oblique moving deformable barrier test procedure 
(No. 2018-01-1055). SAE Technical Paper, available at https://www.regulations.gov/document/NHTSA-2019-0106-0005. The discussion 
here briefly summarizes some of the relevant results from this 
report. This testing is not being considered as an evaluation of the 
ATD's repeatability and reproducibility because in order to provide 
a meaningful ATD R&R analysis, control of the test conditions must 
be exercised. Component tests, such as the qualification tests, are 
more readily controlled and thus may be expected to provide the best 
estimates of a dummy's R&R. Sled testing provides an efficient 
alternative to vehicle crash testing and offers insight into the 
dummy's performance as a complete system. In full-vehicle crash 
testing, however, the variation contributed by the vehicle (e.g., 
variation in structural materials) and the overall test procedure 
make it difficult to identify the variability attributable to the 
dummy itself. Additionally, the severity of the test conditions 
utilized for R&R assessment must also be considered. For example, if 
the test conditions are so severe that the responses are near or 
beyond the dummy's mechanical limits or electronic capacity, then 
the corresponding R&R analysis may not be meaningful. See generally 
Rhule et al (2005).
---------------------------------------------------------------------------

    There were no signs of damage beyond normal wear and tear, and no 
part replacements were necessary. We did observe some sensor anomalies 
or failures to sensors, but almost all the sensors that failed were 
non-critical--for example off-axis channels (e.g., right femur X-axis 
force) or sensors not used in the calculation of injury criteria (e.g., 
lower neck load cell, foot accelerometers). See Appendix F. Such sensor 
anomalies can also occur in other Part 572 ATDs, such as the HIII-50M 
and HIII-05F used in Frontal NCAP testing. In the past six years of 
Frontal NCAP testing, there was an average of one failed ATD sensor 
channel per crash test (0.68  1.08), with five of those 
instances occurring in a critical channel.
    Many of these anomalies were the results of loose Amphenol pins. 
These are the electrical contacts inside of the connectors used to 
interface the THOR-50M umbilical cables with the specific data 
acquisition system of the test facility. These connectors are used to 
prevent the need for cutting wires and attaching lab-specific 
connectors each time an ATD is sent to a new facility with a different 
data acquisition system. In practice, ATDs sent to test facilities for 
the execution of regulation or consumer information testing will often 
remain on-site for an extended period of time, which makes laboratory-
specific connectors more feasible. Such issues would not exist for 
THOR-50M ATDs with in-dummy data acquisition systems. Many of the 
sensor failures that occurred were in non-critical instrumentation, for 
example off-axis channels or sensors not used in the calculation of 
injury criteria. For research tests, a larger number of sensors are 
recorded for the sake of completeness and post-test investigation; in a 
regulatory or consumer information testing environment, these channels 
may not be recorded. If the user does want to record such sensors, they 
would need to be repaired or replaced before pre-test qualification for 
the next vehicle crash test.
    The only sensor anomalies related to the calculation of injury 
criteria were in the chest and abdomen, but, once linearized, scaled, 
filtered, and converted to three-dimensional resultant deflection local 
spine coordinate system, these ``blips'' were no longer evident; thus 
they would not influence the calculation of injury risk for this 
occupant. These voltage drops are characteristic of the abrupt 
decreases in the IR-TRACC voltage time-history described in Section 
III.E.2. See Appendix F.
3. FMVSS No. 208 Unbelted Vehicle Crash Tests
    NHTSA performed a series of unbelted vehicle crash tests required 
in FMVSS No. 208. The results are briefly summarized in this section 
and are discussed in more detail in the referenced paper.\183\ FMVSS 
No. 208 specifies a frontal crash test into a rigid barrier with the 
barrier angle at 0 degrees to  30 degrees at between 20 mph 
(32 km/h) and 25 mph (40 km/h), inclusive, with an unbelted 50th 
percentile male dummy seated at either front outboard seat.\184\
---------------------------------------------------------------------------

    \183\ Saunders, J., Parent, D., Martin, P., 2023. THOR-50M 
Fitness Assessment In FMVSS No. 208 Unbelted Crash Tests. In: 
Proceedings of the 24th International Technical Conference for the 
Enhanced Safety of Vehicles (No. 23-0339). Available at: https://www-esv.nhtsa.dot.gov/Proceedings/27/27ESV-000339.pdf.
    \184\ S14.5.2; S5.1.2(b).
---------------------------------------------------------------------------

    NHTSA ran two sets of tests. First, we ran this test at the highest 
regulatory speed of 40 km/h (25 mph) for crash geometries of 30 degrees 
to the left, 30 degrees to the right, and perpendicular (12 tests). 
Second, we ran a modified version of this test, with an elevated speed 
of 48 km/h (30 mph) for crash geometries of 30 degrees to the left and 
right (six tests). We tested with two different THOR-50M ATDs, both 
manufactured by Humanetics and built to the 2018 drawing package 
(except that one ATD (EG2595) was fitted with the proposed optional in-
dummy DAS). For these tests, the laboratory test procedures for FMVSS 
No. 208 \185\ were followed, with the exception of the seating 
procedure, for which the Revised THOR 50th Percentile Male Dummy 
Seating Procedure \186\ was followed. The ATD was instrumented so that 
all injury criteria defined for the HIII-50M in FMVSS No. 208 and in 
the THOR-50M Injury Criteria Report could be calculated. A total of 19 
tests were run on four different vehicle models

[[Page 61943]]

(the Honda Accord, Mazda CX-5, Chevrolet Equinox, and Ford Escape).
---------------------------------------------------------------------------

    \185\ National Highway Traffic Safety Administration (2008). 
Laboratory Test Procedure for FMVSS 208, Occupant Crash Protection, 
TP208-14.
    \186\ National Highway Traffic Safety Administration (2020). 
Revised THOR 50th Percentile Male Dummy Seating Procedure, June 
2019. Regulations.gov Docket ID NHTSA-2019-0106-0006, available at 
https://www.regulations.gov/document/NHTSA-2019-0106-0006.
---------------------------------------------------------------------------

    This study showed that the THOR-50M, when exercised in unbelted 
frontal rigid barrier testing, experienced only minor issues. We 
performed a full set of qualification tests before the test series, a 
partial qualification test series \187\ after each test, and a full 
qualification test series halfway through the test series. In all 
cases, the THOR-50Ms met the qualification specifications without need 
for part replacement or other refurbishment. In addition, each ATD was 
inspected after each test for damage and to investigate sensor 
anomalies. While no parts were found to be in need of replacement, 
there were some sensor anomalies and damage. One of the ATDs did not 
experience any sensor anomalies or damage during testing, while the 
other ATD experienced some sensor anomalies that were repairable, while 
others were not. The sensors that were not repaired were non-critical 
channels (for example, the left tibia mid-shaft X-axis accelerometer), 
thus a decision was made to continue testing instead of repairing or 
replacing the sensors, which would have caused delays in the test 
schedule. The quantity and severity of sensor anomalies were similar to 
those experienced in testing with the HIII-50M, especially considering 
increased sensor count and level of complexity of the THOR-50M. Aside 
from minor wear and tear (e.g., scrapes on the top of the head skin of 
one ATD were noted after one test) there was no damage to either ATD 
and both met all qualification specifications.
---------------------------------------------------------------------------

    \187\ To maximize efficiency, the partial qualification test 
series only included the tests that did not require any disassembly 
of dummy components: head, upper thorax, lower thorax, lower 
abdomen, and left/right upper leg. The face impact test was not 
included because direct impact to the face was not expected during 
this test series.
---------------------------------------------------------------------------

    Based on these observations, NHTSA tentatively concludes that THOR-
50M is sufficiently durable for use in FMVSS No. 208 unbelted testing, 
even at an elevated closing speed. Overall, this unbelted test series 
provides additional assurance that the THOR-50M units are durable and 
stand up well under testing, with the amount of wear and tear normal 
for our test dummies, and that NHTSA's THOR-50M design specifications 
have resulted in highly uniform and durable units.

C. Sensitivity to Restraint System Performance

    NHTSA's testing with the THOR-50M has also highlighted its ability 
to detect differences in restraint system performance. One example of 
this occurred in the Oblique OMDB testing described above in Section 
VII.B.2.\188\ This testing involved vehicles of the same model and 
model year with a THOR-50M seated in each front outboard seat. In one 
series of tests which included three Oblique OMDB crash tests of the 
same vehicle make and model, the THOR-50Ms seated in the right front 
passenger seat showed a much wider variation in injury assessment 
values related to head injury risk than the THOR-50Ms seated in the 
driver's seat. A thorough investigation of the test data, including 
inspection of the high-speed video, revealed that the right front 
passenger air bag did not function consistently to manage the ride-down 
of the occupant: the high-speed images revealed differences in air bag 
deployment, interaction between the head and the air bag, and contact 
between the head and the instrument panel. Inspection of the air bag 
revealed tears in the air bags in two of the three tests, with the 
largest tears associated with the highest injury assessment 
values.\189\ This is one example of how the innovative features of the 
THOR-50M can help lead to improved vehicle safety.
---------------------------------------------------------------------------

    \188\ Saunders, J., & Parent, D. (2018). Repeatability and 
reproducibility of oblique moving deformable barrier test procedure 
(No. 2018-01-1055).
    \189\ These results were shared with the vehicle manufacturer, 
which instituted a series of modifications. In a later test of the 
vehicle, there were no passenger air bag tears evident, and the head 
injury criteria were similar to those measured in the previous tests 
that did not appear to result in air bag tears.
---------------------------------------------------------------------------

VIII. Intellectual Property

    While there is no specific prohibition on specifying a patented 
component, copyrighted design, or name-brand product in Part 572, NHTSA 
has been mindful of the legislative history of the Safety Act and its 
own responsibility under statute to make all information, patents, and 
developments related to a research and development activity available 
to the public where it makes more than a minimal contribution to the 
activity.\190\ This understanding has guided dummy development at NHTSA 
for many years and explains why NHTSA has not incorporated into final 
rules materials owned by third parties except in rare cases (discussed 
below). The legislative history of the Safety Act shows that while 
Congress explicitly declined to include a provision preventing use of 
patents by the agency in standards, Congress did ``assume[ ] that the 
Secretary is not likely to adopt a standard which can be met only by 
using a single patented device, and that the Secretary would, before 
doing so, take steps to obtain an understanding from the patent holder 
that he would supply the item or grant licenses on reasonable terms.'' 
\191\ In addition, NHTSA itself plays a significant role in the 
testing, evaluation and performance verification of dummies and 
provides a substantial amount of information to the public to identify 
the basis for improvement in testing devices to ensure the 
repeatability and reproducibility of results. The outcome of the 
agency's involvement has been an interest in making sure the test 
device is available for use without restriction to the public.
---------------------------------------------------------------------------

    \190\ 49 U.S.C. 30182(f).
    \191\ S. Rep. No. 89-1301, at 15, reprinted in U.S.C.C.A.N. 
2709, 2723.
---------------------------------------------------------------------------

    To be clear, there are also several potential concerns with 
specifying proprietary components. They may be modified by the 
proprietary source such that original is no longer available, and the 
new part no longer fits. The proprietary source may alter the part in 
ways that change the response of the dummy, such that dummies with the 
newer part do not provide the same response as dummies with the older 
part. Components produced by only one manufacturer are not subject to 
competitive sales pressures. And the manufacturer of a sole-source part 
may simply cease manufacturing the part.
    For these reasons, NHTSA has generally avoided specifying in Part 
572 patented components or copyrighted designs without either securing 
agreement from the rights-holder for the free use of the item or to 
license it on reasonable terms \192\ or developing an alternative 
unencumbered by any rights claims.\193\
---------------------------------------------------------------------------

    \192\ See, e.g., 38 FR 8455 (Apr. 2, 1973) (NPRM for the initial 
50th percentile male dummy) (``To the knowledge of this agency, the 
only patent on a component of the specified dummy is one on the knee 
held by Alderson, and that company has stated to the NHTSA that it 
will license production under its patent for a reasonable 
royalty.'')
    \193\ See, e.g., 65 FR 17180, 17187 (Mar. 31, 2000) (final rule 
for twelve-month-old child dummy) (declining to incorporate a 
copyrighted PADI developed by an ATD manufacturer and instead 
incorporating a NHTSA-authored PADI).
---------------------------------------------------------------------------

    As noted earlier in the preamble (Section III), we are specifying 
some patented parts but not without specifying suitable alternates 
where no intellectual property claims apply. We briefly discuss these 
below.

Shoulder

    As explained earlier, we are proposing to include two alternative 
shoulder specifications: the SD-3 shoulder and the alternate shoulder.
    Humanetics has two patents on the SD-3 shoulder: one describes a 
mechanical shoulder joint assembly and the other describes an upper arm

[[Page 61944]]

assembly with a load cell.\194\ The shoulder joint is formed using a 
pivot connected to a spring element inside of a housing, which has an 
adjustable element to control the friction of the joint. Humanetics is 
currently the sole manufacturer of the SD-3 shoulder in the United 
States.
---------------------------------------------------------------------------

    \194\ U.S. Patent Nos. 9,514,659 (upper arm assembly) and 
9,799,234 (shoulder joint assembly).
---------------------------------------------------------------------------

    In order to avoid potential concerns with specifying a patented 
part as the sole specification, NHTSA has developed an alternative to 
the SD-3 shoulder. The alternate shoulder does not include the 
adjustable friction element, and does not use a coil, clock, or watch 
spring mechanism. Instead, the alternate shoulder design uses a molded 
rubber cylinder acting as a torsion bar. The response of the rubber 
cylinder can be tuned by both changes in material and changes in 
geometry, such as removal of material to create voids of different 
sizes and shapes. This lack of a friction adjustment in the alternate 
shoulder is a change in the functional aspect of the design. 
Accordingly, with the significant differences noted, we are proposing 
to specify the use of either the alternate shoulder or the SD-3 
shoulder.

Chest Instrumentation

    NHTSA is proposing the IR-TRACC and the S-Track as permissible 
alternate instrumentation. While NHTSA is not aware of any patent 
protection on the IR-TRACC, it is manufactured only by Humanetics. 
There is a patent on the S-Track, and NHTSA's understanding is that the 
S-Track is currently manufactured only by ATD-LabTech, which was 
recently acquired by Humanetics.
    We believe that specifying the design such that either the IR-TRACC 
or the S-Track could be used would be sufficient to ensure 
instrumentation availability to dummy users. We seek comment on this.

IX. Consideration of Alternatives

    NHTSA is not aware of a 50th percentile male ATD intended for use 
in frontal or frontal oblique crash tests and more advanced than the 
HIII-50M, other than the THOR-50M. Throughout this document we have 
discussed various alternative configurations, specifications, and tests 
that we have considered in developing the proposal and on which we are 
seeking comment.
    As discussed in more detail in the rulemaking analyses section, 
Executive Order 13609 provides that international regulatory 
cooperation can reduce, eliminate, or prevent unnecessary differences 
in regulatory requirements. Similarly, Sec.  24211 of the 
Infrastructure, Investment, and Jobs Act \195\ instructs DOT to 
harmonize the FMVSS with global regulations to the maximum extent 
practicable (for example, to the extent that harmonization would be 
consistent with the Safety Act).
---------------------------------------------------------------------------

    \195\ H.R. 3684 (117th Congress) (2021).
---------------------------------------------------------------------------

    The only regulatory authority or consumer ratings program we are 
aware of that currently uses the THOR-50M is Euro NCAP. Euro NCAP TB026 
references the August 2018 drawing package,\196\ the September 2018 
Qualification Procedures,\197\ and the August 2018 PADI.\198\ Although 
TB026 largely follows these documents, it does depart from them in 
several ways. Those differences have been identified and discussed in 
the relevant sections of the preamble and are summarized in Table 20. 
The tentative reasons for those differences are explained in detail in 
the relevant section of the preamble. In general, we believe that those 
differences are justified given NHTSA's experience testing with the 
THOR-50M in frontal rigid barrier and frontal oblique vehicle crash 
test modes, and the necessity of ensuring that a dummy specified for 
use in regulatory compliance testing be objectively specified.
---------------------------------------------------------------------------

    \196\ Sec.  1.1.
    \197\ Sec.  2.1.
    \198\ Sec.  3.1.

Table 20--Summary of Differences Between the THOR-50M as Proposed and as
                     Specified for Use in Euro NCAP
------------------------------------------------------------------------
              Issue                    Proposal            Euro NCAP
------------------------------------------------------------------------
Design & Construction:
    Split shoulder pad..........  Not proposed......  Under
                                                       consideration.
    Spine.......................  Spine Pitch Change  Four-Position
                                   Joint.              Spine Box.
    Lower Leg...................  THOR-specific       HIII-50M lower
                                   lower leg.          leg.
Instrumentation:
    S-Track/IR-TRACC............  IR-TRACC or S-      IR-TRACC, S-Track,
                                   Track.              or KIR-TRACC
                                                      Does not specify
                                                       the systems part-
                                                       by-part with
                                                       engineering
                                                       drawings.
    In-dummy DAS................  Permitted as        TB026 requires an
                                   optional            in-dummy DAS.
                                   configuration       TB029 currently
                                   with part-by-part   does not specify
                                   engineering         any specific in-
                                   drawings            dummy DAS,
                                   compatible with     although earlier
                                   the SLICE6 and      versions of TB029
                                   any other           did specify a few
                                   similarly-          different
                                   configured system.  approved in-dummy
                                                       DAS systems.
                                                      Does not specify
                                                       the systems part-
                                                       by-part with
                                                       engineering
                                                       drawings.
Qualification Tests:
    Acceptance interval midpoint  Based on R&R test   Basis not
                                   data.               identified in
                                                       TB026.
    Acceptance interval width...   10%    Varies from 1% to 10%.
    Upper thorax................  Ratio of Z-axis to  Specifies ratio of
                                   X-axis deflection   Z-axis to X-axis
                                   not specified as    deflection as
                                   test parameter.     test parameter.
    Face impact test............  Specified.........  Not specified.
    Knee slider.................  Specified.........  Certified to SAE
                                                       J2876.
Lower legs......................  Ankle inversion/    Certified to Annex
                                   eversion; Ball of   10 of ECE
                                   foot; heel.         Regulation No.
                                                       94.
------------------------------------------------------------------------

[[Page 61945]]

X. Lead Time

    Since this rulemaking action itself would not impose requirements 
on anyone, we are proposing that the final rule would be effective on 
publication in the Federal Register.

XI. Incorporation by Reference

    Under regulations issued by the Office of the Federal Register (1 
CFR 51.5(a)), an agency, as part of a final rule that includes material 
incorporated by reference, must summarize in the preamble of the final 
rule the material it incorporates by reference and discuss the ways the 
material is reasonably available to interested parties or how the 
agency worked to make materials available to interested parties.
    In this proposed rule, NHTSA incorporates by reference a technical 
data package for the THOR-50M. The technical data package consists of 
two-dimensional engineering drawings and a parts list; procedures for 
assembly, disassembly, and inspection (PADI); and qualification 
procedures. Copies of these documents are available in the research 
docket identified earlier in this document. Interested persons can 
download a copy of the materials or view the materials online by 
accessing www.Regulations.gov. The material is also available for 
inspection at the Department of Transportation, Docket Operations, Room 
W12-140, 1200 New Jersey Avenue SE, Washington, DC Telephone: 202-366-
9826. If the proposed rule is finalized, final versions of these 
documents would be placed in a docket that would be readily available 
to the public online (via regulations.gov) and in-person at DOT 
headquarters.
    Although agency-created documents are presumptively ineligible for 
incorporation by reference, they may be approved for incorporation by 
the Office of the Federal Register if they (among other things) consist 
of criteria, specifications, or illustrations; are reasonably available 
to the class of persons affected; are easy to handle; and possesses 
other unique or highly unusual qualities.\199\
---------------------------------------------------------------------------

    \199\ See 1 CFR 51.7(b) (``The Director will assume that a 
publication produced by the same agency that is seeking its approval 
is inappropriate for incorporation by reference. A publication 
produced by the agency may be approved, if, in the judgment of the 
Director, it meets the requirements of paragraph (a) and possesses 
other unique or highly unusual qualities. A publication may be 
approved if it cannot be printed using the Federal Register/Code of 
Federal Regulations printing system.''); (a)(2)(i)(``published data, 
criteria, standards, specifications, techniques, illustrations, or 
similar material''); (a)(3)(``reasonably available to and usable by 
the class of persons affected''); (a)(3)(i)(``The completeness and 
ease of handling of the publication'').
---------------------------------------------------------------------------

    We believe these documents (which were created by NHTSA) meet these 
criteria. Except for the qualification procedures, NHTSA typically 
incorporates these elements of the technical data package by reference. 
NHTSA has not typically incorporated the qualification procedures by 
reference. Doing so is a departure from the other ATDs currently 
specified in Part 572, for which the qualification tests are set out in 
full in the regulatory text in each of the relevant paragraphs 
(corresponding to that ATD) in part 572. We are proposing a separate 
qualification procedures document for the THOR-50M because the THOR-50M 
qualification procedures involve procedures that are made clearer by 
photographs and diagrams that are not amenable to publication in the 
CFR.\200\ We believe this extra level of detail will be helpful for end 
users who are attempting to qualify the ATD. We seek comment on this.
---------------------------------------------------------------------------

    \200\ The qualification procedures document states that the 
photographs are provided for reference only.
---------------------------------------------------------------------------

XII. Regulatory Analyses

Executive Order (E.O.) 12866, E.O. 13563, E.O. 14094, and DOT 
Regulatory Policies and Procedures

    NHTSA has considered the impacts of this regulatory action under 
Executive Orders 12866, 13563, 14094, and the Department of 
Transportation's regulatory policies and procedures.\201\ This 
rulemaking action was not reviewed by the Office of Management and 
Budget under E.O. 12866. It is also not considered ``of special note to 
the Department'' under DOT Order 2100.6A. We have considered the 
qualitative costs and benefits of the proposed rule under the 
principles of E.O. 12866.
---------------------------------------------------------------------------

    \201\ 49 CFR, Part 5, Subpart B; Department of Transportation 
Order 2100.6A, Rulemaking and Guidance Procedures, June 7, 2021.
---------------------------------------------------------------------------

    This document would amend 49 CFR part 572 by adding design and 
performance specifications for an advanced test dummy representative of 
a 50th percentile adult male that the agency would possibly use in 
FMVSS No. 208 front crash tests and for research purposes. This Part 
572 proposed rule would not impose any requirements on anyone. 
Businesses are affected only if they choose to manufacture or test with 
the dummy.
    There are benefits associated with this rulemaking but they are not 
readily quantifiable. The THOR-50M is an advanced dummy with advantages 
over existing dummies with respect to biofidelity, instrumentation, 
injury prediction, and evaluation of vehicle performance. The dummy is 
currently used for testing by Euro NCAP, and may be incorporated in ECE 
R137. It is also likely being used by vehicle and restraint 
manufacturers for testing, research, and development.
    Accordingly, NHTSA is considering a proposal to incorporate the 
THOR-50M into FMVSS No. 208, ``Occupant crash protection,'' for use in 
frontal crash compliance testing at the manufacturers' option.\202\ 
This contemplated rulemaking action would permit manufacturers to 
direct NHTSA to use the THOR-50M in belted and unbelted barrier crash 
testing of the vehicles they produce instead of the HIII-50M ATD in 
NHTSA's compliance tests. Incorporating the dummy in Part 572 will 
enable manufacturers and others to streamline testing, choosing to use 
THOR-50M in place of the HIII-50M, potentially reducing the number of 
tests they run, and leveraging the value of the tests they do run.
---------------------------------------------------------------------------

    \202\ FMVSS No. 208 THOR-50M Compliance Option (RIN 2127-AM21), 
Fall 2023 Unified Agenda of Regulatory and Deregulatory Actions; 
Department of Transportation, available at https://www.reginfo.gov/public/do/eAgendaViewRule?pubId=202304&RIN=2127-AM21.
---------------------------------------------------------------------------

    Incorporating the THOR-50M into Part 572 would also have other 
benefits beyond use in NHTSA's compliance testing. The ability of the 
THOR-50M to potentially monitor additional injury modes and its 
improved biofidelity may facilitate the development and introduction of 
innovative occupant crash protection features. While the purpose of 
Part 572 is to ``describe the anthropomorphic test devices that are to 
be used for compliance testing of motor vehicles and motor vehicle 
equipment with motor vehicle safety standards,'' it also serves as a 
definition of the ATD for other purposes as well, such as consumer 
information crash testing, standards and regulations in other 
transportation modes, and research. As such, it would be to the benefit 
of government, academia, and the multi-modal transportation industry to 
include a definition of the THOR-50M ATD in Part 572. In addition, the 
availability of this dummy in a regulated format would be beneficial by 
providing a suitable, stabilized, and objective test tool to the safety 
community for use in better protecting occupants in frontal impacts.
    The costs associated with the THOR-50M only affect those who choose 
to use the THOR-50M. This rule would not impose any requirements on 
anyone. If incorporated into FMVSS No. 208, NHTSA would use the dummy 
in its compliance testing of the requirements

[[Page 61946]]

at the option of a regulated entity, but regulated entities are not 
required to use the dummy or assess the performance of their products 
in the manner specified in the FMVSSs.
    NHTSA has found that the cost of a THOR-50M corresponding to the 
2023 drawing package has been approximately $550,000 to $750,000 
depending on whether an in-dummy DAS is installed and the level of 
instrumentation. The minimum set of instrumentation needed for 
qualification testing includes 66 channels. If the S-Track were used 
instead of the IR-TRACC, the total cost would be roughly the same.
    In addition to these costs, as with any ATD, dummy refurbishments 
and part replacements are an inherent part of ATD testing. Various 
parts will likely have to be refurbished or replaced, but we generally 
do not know which parts are likely to be worked on the most. As we note 
in the NPRM, however, the face foam appears to need more frequent 
replacement but this should not add appreciably to the overall cost. 
Because the dummies are designed to be reusable, costs of the dummies 
and of parts can be amortized over a number of tests. While the 
expected maintenance costs for the THOR-50M are expected to be higher 
than those for less complex dummies such as the HIII-50M, these costs 
are expected to be similar to advanced dummies such as the WorldSID.
    There are minor costs associated with conducting the qualification 
tests. Most of the qualification fixtures are common with those used to 
qualify other Part 572 dummies (including the neck pendulum and the 
probes used in the head, upper thorax and lower thorax tests). Some 
additional equipment unique to the THOR-50M may be fabricated from 
drawings within the technical data package, for an estimated cost of 
about $50,000. This includes the cost to fabricate the torsion fixture 
for the neck torsion test, the lower abdomen probe face assembly, 
impact probes not used for other Part 572 dummies (or weighted collars 
to achieve the specified mass), and test apparatus for the lower leg 
tests (including the dynamic impactor, external positioning bracket, 
dynamic inversion/eversion bracket, lower leg mounting bracket, lower 
leg zero bracket, Achilles fixture, load cell mounting assembly, knee 
slider load distribution bracket, and tibia adapter). The costs of the 
instrumentation equipment needed to perform the qualification tests 
amounts to about an additional $4,400 (two angular rate sensors, $850 
apiece; two test probe accelerometers, $800 apiece; one rotary 
potentiometer, $1,100).

Regulatory Flexibility Act

    Pursuant to the Regulatory Flexibility Act (5 U.S.C. 601 et seq., 
as amended by the Small Business Regulatory Enforcement Fairness Act 
(SBREFA) of 1996), whenever an agency is required to publish a proposed 
or final rule, it must prepare and make available for public comment a 
regulatory flexibility analysis that describes the effect of the rule 
on small entities (i.e., small businesses, small organizations, and 
small governmental jurisdictions), unless the head of the agency 
certifies the rule will not have a significant economic impact on a 
substantial number of small entities. The Small Business 
Administration's regulations at 13 CFR part 121 define a small 
business, in part, as a business entity ``which operates primarily 
within the United States.'' (13 CFR 121.105(a)).
    We have considered the effects of this rulemaking under the 
Regulatory Flexibility Act. I hereby certify that this rulemaking 
action would not have a significant economic impact on a substantial 
number of small entities. This action would not have a significant 
economic impact on a substantial number of small entities because the 
addition of the test dummy to Part 572 would not impose any 
requirements on anyone. This NPRM only proposes to include the dummy in 
NHTSA's regulation for crash test dummies; it does not propose NHTSA's 
use of the ATD in agency testing or require anyone to manufacture the 
dummy or to test motor vehicles or motor vehicle equipment with it.

National Environmental Policy Act

    NHTSA has analyzed this proposed rule for the purposes of the 
National Environmental Policy Act and determined that it would not have 
any significant impact on the quality of the human environment.

Executive Order 13045 and 13132 (Federalism)

    Executive Order 13045 (62 FR 19885, April 23, 1997) applies to any 
rule that: (1) is determined to be ``economically significant'' as 
defined under E.O. 12866, and (2) concerns an environmental, health, or 
safety risk that NHTSA has reason to believe may have a 
disproportionate effect on children. If the regulatory action meets 
both criteria, we must evaluate the environmental health or safety 
effects of the planned rule on children and explain why the planned 
regulation is preferable to other potentially effective and reasonably 
feasible alternatives considered by us.
    This proposed rule is not subject to the Executive Order because it 
is not economically significant as defined in E.O. 12866.
    NHTSA has examined this proposed rule pursuant to Executive Order 
13132 (64 FR 43255, August 10, 1999) and concluded that no additional 
consultation with States, local governments or their representatives is 
mandated beyond the rulemaking process. The agency has concluded that 
the proposed rule would not have federalism implications because the 
proposed rule would not have ``substantial direct effects on the 
States, on the relationship between the national government and the 
States, or on the distribution of power and responsibilities among the 
various levels of government.'' This proposed rule would not impose any 
requirements on anyone. Businesses will be affected only if they choose 
to manufacture or test with the dummy.
    Further, no consultation is needed to discuss the preemptive effect 
of this proposed rule. While NHTSA's safety standards can have 
preemptive effect, the proposed rule would amend 49 CFR part 572 and is 
not a safety standard. This Part 572 proposed rule would not impose any 
requirements on anyone.

Civil Justice Reform

    With respect to the review of the promulgation of a new regulation, 
section 3(b) of Executive Order 12988, ``Civil Justice Reform'' (61 FR 
4729, February 7, 1996) requires that Executive agencies make every 
reasonable effort to ensure that the regulation: (1) Clearly specifies 
the preemptive effect; (2) clearly specifies the effect on existing 
Federal law or regulation; (3) provides a clear legal standard for 
affected conduct, while promoting simplification and burden reduction; 
(4) clearly specifies the retroactive effect, if any; (5) adequately 
defines key terms; and (6) addresses other important issues affecting 
clarity and general draftsmanship under any guidelines issued by the 
Attorney General. This document is consistent with that requirement.
    Pursuant to this Order, NHTSA notes as follows.
    The issue of preemption is discussed above in connection with E.O. 
13132. NHTSA notes further that there is no requirement that 
individuals submit a petition for reconsideration or pursue other 
administrative proceeding before they may file suit in court.

[[Page 61947]]

Paperwork Reduction Act

    Under the Paperwork Reduction Act of 1995, a person is not required 
to respond to a collection of information by a Federal agency unless 
the collection displays a valid control number from the Office of 
Management and Budget (OMB). This proposed rule would not have any 
requirements that are considered to be information collection 
requirements as defined by the OMB in 5 CFR part 1320.

National Technology Transfer and Advancement Act

    Section 12(d) of the National Technology Transfer and Advancement 
Act of 1995 (NTTAA), Public Law 104-113, section 12(d) (15 U.S.C. 272) 
directs NHTSA to use voluntary consensus standards in its regulatory 
activities unless doing so would be inconsistent with applicable law or 
otherwise impractical. Voluntary consensus standards are technical 
standards (e.g., materials specifications, test methods, sampling 
procedures, and business practices) that are developed or adopted by 
voluntary consensus standards bodies. The NTTAA directs NHTSA to 
provide Congress, through OMB, explanations when the agency decides not 
to use available and applicable voluntary consensus standards.
    The following voluntary consensus standards have been used in 
developing the THOR-50M:
     SAE J211-1, Instrumentation for impact test--Part 1: 
Electronic Instrumentation, Version 2014-03-31
     SAE J1733, Sign Convention for Vehicle Crash Testing, 
Version 2007-11-02.
     SAE J2570, Performance specifications for anthropomorphic 
test device transducers, Version 2009-08-12.
     SAE J2876, Low Speed Knee Slider Test Procedure for the 
Hybrid III 50th Male Dummy, Version 2015-05-07.
     ISO-MME Task Force, 2015-04-15 proposed mnemonic codes for 
the THOR-50M.

Unfunded Mandates Reform Act

    The Unfunded Mandates Reform Act of 1995 (Pub. L. 104-4) (UMRA) 
requires agencies to prepare a written assessment of the costs, 
benefits, and other effects of proposed or final rules that include a 
Federal mandate likely to result in the expenditures by States, local 
or tribal governments, in the aggregate, or by the private sector, of 
$100 million or more (adjusted annually for inflation with base year of 
1995) in any one year. Adjusting this amount by the implicit gross 
domestic product price deflator for 2022 results in $177 million 
(111.416/75.324 = 1.48). The assessment may be included in conjunction 
with other assessments, as it is here. UMRA requires the agency to 
select the ``least costly, most cost-effective or least burdensome 
alternative that achieves the objectives of the rule.''
    This proposed rule would not impose any unfunded mandates under the 
UMRA. This proposed rule does not meet the definition of a Federal 
mandate because it does not impose requirements on anyone. It amends 49 
CFR part 572 by adding design and performance specifications for a 50th 
percentile adult male frontal crash test dummy that the agency could 
use in FMVSS No. 208 and for research purposes. This proposed rule 
would affect only those businesses that choose to manufacture or test 
with the dummy. It would not result in costs of $100 million or more 
(adjusted for inflation) to either State, local, or tribal governments, 
in the aggregate, or to the private sector.

Plain Language

    Executive Order 12866 and E.O. 13563 require each agency to write 
all rules in plain language. Application of the principles of plain 
language includes consideration of the following questions:
     Have we organized the material to suit the public's needs?
     Are the requirements in the rule clearly stated?
     Does the rule contain technical language or jargon that 
isn't clear?
     Would a different format (grouping and order of sections, 
use of headings, paragraphing) make the rule easier to understand?
     Would more (but shorter) sections be better?
     Could we improve clarity by adding tables, lists, or 
diagrams?
     What else could we do to make the rule easier to 
understand?
    If you have any responses to these questions, please include them 
in your comments on this proposal.

Regulation Identifier Number

    The Department of Transportation assigns a regulation identifier 
number (RIN) to each regulatory action listed in the Unified Agenda of 
Federal Regulations. The Regulatory Information Service Center 
publishes the Unified Agenda in April and October of each year. You may 
use the RIN contained in the heading at the beginning of this document 
to find this action in the Unified Agenda.

Privacy Act

    In accordance with 5 U.S.C. 553(c), DOT solicits comments from the 
public to better inform its rulemaking process. DOT posts these 
comments, without edit, to www.regulations.gov, as described in the 
system of records notice, DOT/ALL-14 FDMS, accessible through 
www.dot.gov/privacy. In order to facilitate comment tracking and 
response, we encourage commenters to provide their name, or the name of 
their organization; however, submission of names is completely 
optional. Anyone is able to search the electronic form of all comments 
received into any of our dockets by the name of the individual 
submitting the comment (or signing the comment, if submitted on behalf 
of an association, business, labor union, etc.). You may review DOT's 
complete Privacy Act Statement in the Federal Register published on 
April 11, 2000 (Volume 65, Number 70; Pages 19477-78).

XIII. Public Participation

How do I prepare and submit comments?

    Your comments must be written and in English. To ensure that your 
comments are correctly filed in the Docket, please include the agency 
name and the docket number or Regulatory Identification Number (RIN) in 
your comments.
    Your comments must not be more than 15 pages long. (49 CFR 553.21). 
We established this limit to encourage you to write your primary 
comments in a concise fashion. However, you may attach necessary 
additional documents to your comments. There is no limit on the length 
of the attachments.
    If you are submitting comments electronically as a PDF (Adobe) 
file, NHTSA asks that the documents be submitted using the Optical 
Character Recognition (OCR) process, thus allowing NHTSA to search and 
copy certain portions of your submissions.
    Please note that pursuant to the Data Quality Act, in order for 
substantive data to be relied upon and used by the agency, it must meet 
the information quality standards set forth in the OMB and DOT Data 
Quality Act guidelines. Accordingly, we encourage you to consult the 
guidelines in preparing your comments. OMB's guidelines may be accessed 
at https://www.transportation.gov/regulations/dot-information-dissemination-quality-guidelines.

[[Page 61948]]

How can I be sure that my comments were received?

    If you wish the Docket to notify you upon its receipt of your 
comments, enclose a self-addressed, stamped postcard in the envelope 
containing your comments. Upon receiving your comments, the Docket will 
return the postcard by mail.

How do I submit confidential business information?

    You should submit a redacted ``public version'' of your comment 
(including redacted versions of any additional documents or 
attachments) to the docket using any of the methods identified under 
ADDRESSES. This ``public version'' of your comment should contain only 
the portions for which no claim of confidential treatment is made and 
from which those portions for which confidential treatment is claimed 
has been redacted. See below for further instructions on how to do 
this.
    You also need to submit a request for confidential treatment 
directly to the Office of Chief Counsel. Requests for confidential 
treatment are governed by 49 CFR part 512. Your request must set forth 
the information specified in Part 512. This includes the materials for 
which confidentiality is being requested (as explained in more detail 
below); supporting information, pursuant to Part 512.8; and a 
certificate, pursuant to Part 512.4(b) and Part 512, Appendix A.
    You are required to submit to the Office of Chief Counsel one 
unredacted ``confidential version'' of the information for which you 
are seeking confidential treatment. Pursuant to Part 512.6, the words 
``ENTIRE PAGE CONFIDENTIAL BUSINESS INFORMATION'' or ``CONFIDENTIAL 
BUSINESS INFORMATION CONTAINED WITHIN BRACKETS'' (as applicable) must 
appear at the top of each page containing information claimed to be 
confidential. In the latter situation, where not all information on the 
page is claimed to be confidential, identify each item of information 
for which confidentiality is requested within brackets: ``[ ].''
    You are also required to submit to the Office of Chief Counsel one 
redacted ``public version'' of the information for which you are 
seeking confidential treatment. Pursuant to Part 512.5(a)(2), the 
redacted ``public version'' should include redactions of any 
information for which you are seeking confidential treatment (i.e., the 
only information that should be unredacted is information for which you 
are not seeking confidential treatment).
    NHTSA is currently treating electronic submission as an acceptable 
method for submitting confidential business information to the agency 
under Part 512. Please do not send a hardcopy of a request for 
confidential treatment to NHTSA's headquarters. The request should be 
sent to Dan Rabinovitz in the Office of the Chief Counsel at 
[email protected]. You may either submit your request via email 
or request a secure file transfer link. If you are submitting the 
request via email, please also email a courtesy copy of the request to 
John Piazza at [email protected].

Will the agency consider late comments?

    We will consider all comments received before the close of business 
on the comment closing date indicated above under DATES. To the extent 
possible, we will also consider comments that the docket receives after 
that date. If the docket receives a comment too late for us to consider 
in developing a final rule (assuming that one is issued), we will 
consider that comment as an informal suggestion for future rulemaking 
action.

How can I read the comments submitted by other people?

    You may read the comments received by the docket at the address 
given above under ADDRESSES. The hours of the docket are indicated 
above in the same location. You may also see the comments on the 
internet. To read the comments on the internet, go to http://www.regulations.gov. Follow the online instructions for accessing the 
dockets.
    Please note that even after the comment closing date, we will 
continue to file relevant information in the docket as it becomes 
available. Further, some people may submit late comments. Accordingly, 
we recommend that you periodically check the Docket for new material. 
You can arrange with the docket to be notified when others file 
comments in the docket. See www.regulations.gov for more information.

List of Subjects in 49 CFR Part 572

    Motor vehicle safety, Incorporation by reference.

Proposed Regulatory Text

    In consideration of the foregoing, NHTSA proposes to amend 49 CFR 
part 572 as follows:

PART 572--ANTHROPOMORPHIC TEST DEVICES

0
1. The authority citation for part 572 continues to read as follows:

    Authority:  49 U.S.C. 322, 30111, 30115, 30117 and 30166; 
delegation of authority at 49 CFR 1.95.

0
2. Add Subpart X, consisting of Sec. Sec.  572.220 through 572.221, to 
read as follows:
Subpart X--THOR-50M 50th Percentile Male Frontal Impact Test Dummy
Secs.
572.220 Incorporation by reference.
572.221 General description.

Subpart X--THOR-50M 50th Percentile Male Frontal Impact Test Dummy

Sec.  572.220  Incorporation by reference.

    Certain material is incorporated by reference (IBR) into this part 
with the approval of the Director of the Federal Register under 5 
U.S.C. 552(a) and 1 CFR part 51. To enforce any edition other than that 
specified in this section, NHTSA must publish a document in the Federal 
Register and the material must be available to the public. This 
material is available for inspection at the Department of 
Transportation, the National Archives and Records Administration 
(NARA), and in electronic format through regulations.gov. Contact DOT 
at: Department of Transportation, Docket Operations, Room W12-140, 1200 
New Jersey Avenue SE, Washington DC 20590, telephone 202-366-9826. For 
information on the availability of this material at NARA, email 
[email protected] or go to www.archives.gov/federal-register/cfr/ibr-locations. To locate the material on regulations.gov, search for 
Docket No. NHTSA-202X-XXXX. The material may be obtained from the 
source:
    (a) NHTSA Technical Information Services, 1200 New Jersey Ave. SE, 
Washington, DC 20590, telephone 202-366-5965.
    (1) A drawing package entitled, ``THOR-50th Percentile Male with 
Alternate Shoulders Frontal Crash Test Dummy (THOR-50M Male w/Alt. 
Shoulders) Drawings, External Dimensions, and Mass Properties,'' dated 
(and revised) January 2023 (Drawings and Specifications); IBR approved 
for Sec.  572.221.
    (2) A parts list entitled, ``Parts List, THOR-50th Percentile Male 
Frontal Crash Test Dummy with Alternate Shoulders (THOR-50M w/Alt. 
Shoulders)'' dated (and revised) January 2023 (Parts List); IBR 
approved for Sec.  572.221.
    (3) A procedures document entitled ``THOR 50th Percentile Male 
(THOR-50M) Procedures for Assembly, Disassembly, and Inspection 
(PADI)'' dated (and revised) June 2023 (PADI); IBR approved for Sec.  
572.221.

[[Page 61949]]

    (4) A procedures document entitled ``THOR 50th Percentile Male 
(THOR-50M) Qualification Procedures and Requirements'' dated (and 
revised) April 2023 (Qualification Procedures); IBR approved for Sec.  
572.221.

Sec.  572.221  General description.

    (a) The THOR-50M 50th percentile male test dummy is defined by the 
following materials:
    (1) The Drawings and Specifications (incorporated by reference, see 
Sec.  572.220);
    (2) The Parts List (incorporated by reference, see Sec.  572.220);
    (3) The PADI (incorporated by reference, see Sec.  572.220);
    (4) The Qualification Procedures (incorporated by reference, see 
Sec.  572.220).

    Issued under authority delegated in 49 CFR 1.95, 501.4, and 501.
Ann Carlson,
Acting Administrator.
[FR Doc. 2023-19008 Filed 9-6-23; 8:45 am]
BILLING CODE 4910-59-P