[Federal Register Volume 67, Number 86 (Friday, May 3, 2002)]
[Proposed Rules]
[Pages 22381-22387]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 02-11050]


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DEPARTMENT OF TRANSPORTATION

National Highway Traffic Safety Administration

49 CFR Part 572

[Docket No. NHTSA 2002-11838]
RIN 2127-AI39


Anthropomorphic Test Devices; Instrumented Lower Legs for Hybrid 
III-50M and -5F Dummies

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

ACTION: Advance notice of proposed rulemaking.

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SUMMARY: The agency is concerned about the number and severity of lower 
limb injuries in full- and offset-frontal vehicle crashes and the pain 
and suffering, disability, long-term impairment, and high 
rehabilitation costs frequently associated with such injuries. The 
agency believes that there is considerable merit in utilizing crash 
test dummies with instrumented lower legs in vehicle crash tests to 
either assess the risk of occupant injury or mitigate either the number 
or severity of these injuries. This document requests comments on two 
potential devices for assessing the injury potential to lower limbs in 
full- and offset-frontal vehicle collisions. Under consideration are 
two types of instrumented lower legs that can be retrofitted to the 
Hybrid III 50th percentile male and 5th percentile female dummies.

DATES: You should submit your comments early enough to ensure that 
Docket Management receives them not later than August 5, 2002.

ADDRESSES: Comments should refer to the docket number above and be 
submitted to: Docket Section, National Highway Traffic Safety 
Administration, 400 Seventh Street, SW., Washington, DC 20590. 
Alternatively, you may submit your comments electronically by logging 
onto the Docket Management System (DMS) Web site at http://dms.dot.gov. 
Click on ``Help & Information'' or ``Help/Info'' to view instructions 
for filing your comments electronically. Regardless of how you submit 
your comments, you should mention the docket number of this document.
    You may call the Docket at 202-366-9324. Docket hours are 9:30 a.m. 
to 4 p.m., Monday through Friday.

FOR FURTHER INFORMATION CONTACT: For non-legal issues, Mr. Stanley 
Backaitis, Office of Crashworthiness Standards (Telephone: 202-366-
4912) (Fax: 202-493-4329). For legal issues, Mr. Robert Knop, Office of 
the Chief Counsel (Telephone: 202-366-2992) (Fax: 202-366-3820). Both 
can be reached by mail at the National Highway Traffic Safety 
Administration, 400 Seventh Street, SW., Washington, DC 20590.

SUPPLEMENTARY INFORMATION:

Background

    NHTSA is concerned about the number of lower limb injuries in full- 
and offset-frontal vehicle crashes and the pain and suffering, 
disability, long-term impairment, and high rehabilitation costs 
frequently associated with such injuries. A number of research studies 
have shown that knee-tibia-ankle-foot (KsTAF) injuries incurred in 
full- and offset-frontal automobile crashes frequently result in

[[Page 22382]]

severe disability and impairment.\1\ Though they present a less serious 
threat to life than head or chest injuries, these injuries are still 
responsible for a large part of the total vehicle crash-related 
suffering, impairment, and injury costs. An analysis of data from the 
Wisconsin Crash Outcome Data Evaluation System (CODES) project, for 
example, found that one in six occupants hospitalized after a crash had 
serious lower limb injuries.\2\
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    \1\ The tibia is the inner and larger of the two bones 
connecting the knee to the ankle.
    \2\ Karlson, Trudy; Bigelow, Wayne; Beutel, Patricia, ``Serious 
Lower Extremity Injuries from Motor Vehicle Crashes, Wisconsin, 
1991-1994,'' DOT Technical Report No. DOT HS 808 791, September 
1998.
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    The agency estimates that annually approximately 110,000 occupants 
sustain lower limb injuries with a severity rating of 2 or 3 on the 
Abbreviated Injury Scale (AIS).\3\ Slightly less than half of these 
injuries occur below the knee and, of those, ankle and foot injuries 
are the most frequent and responsible for long-term impairment.\4\ 
Female drivers have been found to be at a greater risk of sustaining 
lower extremity injuries than male drivers in two separate studies.\5\ 
The annual cost of AIS 2 and 3 lower extremity injuries to passenger 
car occupants in all automotive crashes has been estimated to run as 
high as $21.5 billion.\6\
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    \3\ National Automotive Sampling System--Crashworthiness Data 
System, 1994-1996, U.S. Department of Transportation, National 
Highway Traffic Safety Administration.
    \4\ Morgan, R., et al., ``Ankle Joint Injury Mechanism for 
Adults in Frontal Automotive Impact,'' Proceedings of the 35th Stapp 
Conference, 1991, and Kuppa, S., et al., ``Lower Extremity Injuries 
and Associated Injury Criteria,'' Seventeenth International 
Technical Conference on the Enhanced Safety of Vehicles, Amsterdam, 
June, 2001.
    \5\ Crandall, et al., ``Biomechanical Response and Physical 
Properties of the Leg, Foot, and Ankle,'' Paper No. 962424, 
Proceedings of the 40th Stapp Conference, Albuquerque, N.M., 
November 1996; and Karlson, Trudy; Bigelow, Wayne; Beutel, Patricia, 
``Serious Lower Extremity Injuries from Motor Vehicle Crashes, 
Wisconsin, 1991-1994,'' DOT Technical Report No. DOT HS 808 791, 
September 1998.
    \6\ Miller, T., ``Societal Costs of Transportation Crashes,'' 
from The Full Costs and Benefits of Transportation, Edited by 
Greene, D., Jone, D., Delucchi, M., Springer-Verlag, 1997 and 
National Automotive Sampling System--Crashworthiness Data System, 
1994-1996, U.S. Department of Transportation, National Highway 
Traffic Safety Administration.
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    Until now, the agency has primarily focused its research and safety 
standard rulemaking on developing and implementing methods, procedures, 
and test tools designed to reduce crash-related injuries to the head, 
neck, and torso because such injuries are the ones most likely to 
result in fatalities. Currently, the only specified injury limits for 
the lower extremities in Standard No. 208 are those for the knee-thigh-
hip complex. Federal Motor Vehicle Safety Standard No. 208 limits the 
axial force measured in the femur to 2250 pounds (10 kN) for the 50th 
percentile adult male Hybrid III dummy and 1530 pounds (6805 N) for the 
5th percentile adult female Hybrid III dummy to minimize knee-thigh-hip 
injuries. Knee-thigh-hip complex injuries account for about 55 percent 
of AIS 2+ lower extremity injuries and 42 percent of the associated 
functional Life-years Lost to Injury.\7\ The remaining 45 percent of 
AIS 2+ lower extremity injuries (and 58 percent of the associated 
functional Life-years Lost to Injury) occur below the knee and are not 
currently addressed by our Standards.
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    \7\ Kuppa, S., et al., ``Lower Extremity Injuries and Associated 
Injury Criteria,'' Paper No. 98-57-070, 17th ESV Conference, 
Windsor, Ontario, Canada, 1998.
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    Now that safety improvements such as air bags and better vehicle 
crashworthiness are being implemented to achieve significant fatality 
reductions, the agency can begin to focus on reducing non-fatal high 
consequence injuries, like those to the lower extremities. The agency 
believes that significant reductions in lower extremity injuries below 
the knees and in the associated costs may be achieved if vehicle 
structures and interior environments are designed to minimize the 
forces exerted on lower extremities in vehicle crashes. A necessary 
first step in developing safer vehicle structures and interiors, 
however, is the availability of adequate tools to measure forces 
exerted on the lower extremities in vehicle crash tests. The agency 
believes that dummy legs currently incorporated into the standards do 
not provide any measurements of crash loads applied to the lower 
extremities below the knee in either full-frontal or offset-frontal 
crash tests.
    The agency believes there would be considerable merit in utilizing 
instrumented lower legs in vehicle crash tests to assess the risk of 
occupant injury. Before the agency does this, however, it wishes first 
to explore the issue of what degree of leg instrumentation and design 
sophistication is needed to adequately and appropriately assess the 
risk of injury and develop more friendly vehicle interiors.
    Two commercially available technologies exist for addressing lower 
leg injuries in frontally-oriented impacts: (1) The Hybrid III/Denton 
(HIII/Denton) instrumented leg and (2) the more recently designed Thor-
Lx Hybrid III Retrofit (Thor-(F)Lx/HIIIr) leg. Both of these 
instrumented lower legs have been designed to fit the existing 50th 
percentile male and 5th percentile female Hybrid III dummies. While the 
Denton leg has been used over a number of years by the automotive 
industry for vehicle development, the newer Thor leg, with 
substantially improved ankle and tibia biofidelity and a broader set of 
instruments, has been evaluated at the research level by a more limited 
number of vehicle manufacturers and research laboratories. After 
assessing received comments and our own data, the agency intends to 
incorporate only one of these two available lower leg designs into part 
572, subpart E (50th percentile male Hybrid III test dummy) and subpart 
O (5th percentile female Hybrid III test dummy). To facilitate a more 
in-depth understanding of the issues and technical details that the 
agency is addressing in this Advance Notice of Proposed Rulemaking, the 
agency is concurrently placing a comprehensive technical support 
document (hereinafter ``Technical Report'') in the docket.\8\
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    \8\ Docket No. NHTSA 2002-11838.
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HIII/Denton Instrumented Leg

    Both the HIII/Denton-50M and the HIII/Denton-5F instrumented leg 
designs consist of an instrumented tibia that fits into the existing 
leg of the dummy, fastening between the knee slider assembly and the 
ankle. The instrumented tibia contains a clevis at the knee that can be 
instrumented to measure the compressive load on each side of the tibia, 
an upper tibia load cell, a tibia tube, and a lower tibia load cell. 
The load cells are each capable of measuring up to five channels of 
data.
    The HIII/Denton instrumented legs employ the existing knee slider, 
knee housing, knee flesh, and knee insert used on the current Hybrid 
III 50th percentile male and 5th percentile female dummies. The knee 
slider assembly can be instrumented with a linear potentiometer to 
measure tibia-femur displacement. An optional ball bearing version knee 
slider is also available that is less influenced by compressive tibia 
loads.
    The ankle and foot assemblies are also unchanged from the standard 
Hybrid III 50th percentile male and 5th percentile female dummies. The 
ankle assembly consists of a ball and socket joint with an adjustable 
frictional resistance level. The level of frictional resistance is 
controlled by a set screw at the ankle ball that can be tightened to 
increase the ankle's resistance to motion. The ankle joint is typically 
set at a ``1G \9\

[[Page 22383]]

suspended'' setting. To assess the rotation of the foot relative to the 
ankle, the foot can be instrumented with accelerometers, two at the 
ankle and one at the toe.
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    \9\ ``1G'' denotes one times the force of gravity.
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    To summarize, the HIII/Denton instrumented leg has the following 
measurement capabilities:

 Upper tibia forces and moments (Fx, Fy, Fz, Mx, My) \10\ (Load 
cell drawing PSA 572-S30)
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    \10\ The following directional designations are used throughout 
this document: ``x'' denotes the fore-aft direction; ``y'' denotes 
the left-right direction; and ``z'' denotes the up-down direction.
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 Lower tibia forces and moments (Fx, Fy, Fz, Mx, My) (Load cell 
drawing PSA 572-S31)
 Knee clevis \11\ loads (Fz left and right portions of the 
clevis) (optional)
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    \11\ A clevis is a single-axis, u-shaped joint allowing angular, 
flexion-type motion between two joined parts.
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 Biaxial accelerations near the ankle (Ax, Az) (optional)
 Uniaxial acceleration near the toe (Az) (optional)
 Knee shear displacement

    Mechanical drawings of the HIII/Denton legs designed for the 50th 
percentile male and 5th percentile female Hybrid III dummies are 
available through Denton ATD, Inc. NHTSA will also make these drawings 
available to the public without proprietary claims when the final rule 
is issued, should the agency decide to incorporate the HIII/Denton 
lower leg assemblies in part 572, subparts E and O.

Cost of HIII/Denton Instrumented Leg

    The costs associated with specifying the use of HIII/Denton lower 
legs in vehicle crash tests may be broken down as follows: (1) The cost 
of the legs themselves; and (2) the data acquisition costs (per test). 
NHTSA estimates the procurement cost to be approximately $32,500 per 
pair for both the 50th percentile male and 5th percentile female 
dummies. The agency believes that most, if not all, vehicle 
manufacturers have already acquired these legs. Accordingly, if the 
agency were to specify the use of the instrumented Denton lower legs in 
vehicle crash testing, the costs associated with acquiring the legs 
would be minimal. With respect to the data acquisition costs, the 
agency estimates that each test utilizing the Denton lower legs would 
cost approximately $2,200 per dummy per crash test, assuming use of the 
upper and lower tibia load cells and knee shear displacement data 
channels.

Thor-Lx/HIIIr and Thor-Flx/HIIIr Instrumented Legs

    Like the HIII/Denton instrumented lower legs, the Thor-(F)Lx/HIIIr 
instrumented lower leg assemblies are designed to fit the 50th 
percentile male Hybrid III dummy (the Thor-Lx/HIIIr) and the 5th 
percentile female Hybrid III dummy (the Thor-FLx/HIIIr). The Thor lower 
leg assemblies incorporate the features of the lower extremities from 
the Thor dummy. The legs were developed by two NHTSA contractors: 
General Engineering and Systems Analysis Company and Applied Safety 
Technologies Corporation (now Denton ATD, Inc.).

Thor-Lx/HIIIr Assembly

    The Thor-Lx/HIIIr assembly mounts directly to the distal end of the 
50th percentile male Hybrid III femur. The Thor-Lx/HIIIr assembly is 
comprised of the Thor-Lx foot and ankle segments, the Thor-Lx tibia 
segment (with integrated Achilles tendon assembly), the standard Hybrid 
III knee housing, a modified Hybrid III knee flesh, new molded side 
knee covers, and the Hybrid III ball bearing knee slider assembly as an 
option.
    The Thor-Lx/HIIIr assembly includes the following new hardware 
elements as compared to the existing Hybrid III leg design:

 Side-mounted knee covers, which augment the existing narrow 
Hybrid III knee housing profile, to improve the realism of knee 
interaction with vehicle knee bolsters;
 A compliant tibia element, which modulates tibia response to 
axial impact to more realistically reflect human response data;
 Provision for independent control of foot mobility about three 
axes of rotation (dorsiflexion/plantarflexion, inversion/eversion, and 
internal/external rotation \12\) by means of progressive rubber 
elements whose characteristics are based upon human data;
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    \12\ Dorsiflexion/plantarflexion rotation is foot motion about 
the ankle's lateral axis. Inversion/eversion rotation is foot motion 
about the ankle's for- and aft-axis. Internal/external rotation is 
foot motion about the tibia's longitudinal axis.
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 A representation of the Achilles tendon load path, which 
contributes to improved realism of tibia axial forces, tibia bending 
moments, and dorsiflexion motion of the foot.

    The Thor-Lx/HIIIr assembly includes the following instrumentation:

 Upper tibia forces and moments (Fx, Fz, Mx, My) (Load cell 
drawing PSA 572-S32)
 Lower tibia forces and moments (Fx, Fy, Fz, Mx, My) (Load cell 
drawing PSA 572-S33)
 Tibia accelerations at mid-shaft (Ax, Ay) (optional)
 Foot angular displacement about 3 axes
 Mid-foot accelerations (3 axes) (optional)
 Achilles tendon tension (uniaxial) (optional)
 Knee shear displacement

    Comprehensive mechanical drawings for the Thor-Lx/HIIIr, together 
with the associated users' manual and proposed certification procedures 
are available on NHTSA's Web site at the following web address: http://
www-nrd.nhtsa.dot.gov/departments/nrd-51/thor__lx/thorlxweb.html.

Thor-FLx/HIIIr Assembly

    The Thor-FLx/HIIIr assembly, which is mounted directly to the 
distal end of the 5th percentile female Hybrid III femur, is nearly 
identical to the Thor-Lx/HIIIr. Given the inherent space constraints of 
the Thor-FLx/HIIIr relative to the Thor-Lx/HIIIr, however, two primary 
design differences were necessary. First, the 5th percentile female 
Thor-FLx/HIIIr assembly has a shaped-cam ankle design that is different 
from that of the 50th percentile male Thor-Lx/HIIIr. Second, the Thor-
FLx/HIIIr contains two custom-made hardware elements that are not used 
on the Thor-Lx/HIIIr: a four-axis upper tibia load cell (drawing PSA 
572-S34) and a five-axis lower tibia load cell (drawing PSA 572-S35). 
These load cells are lighter and smaller than the tibia load cells used 
on the Thor-Lx/HIIIr, enabling a better fit with the smaller diameter 
of the Thor-FLx/HIIIr tibia.
    Comprehensive mechanical drawings for the Thor-FLx/HIIIr, together 
with the associated users' manual and proposed certification procedures 
are available on NHTSA's Web site at the following web address: http://
www-nrd.nhtsa.dot.gov/departments/nrd-51/thor__flx/ThorFLxweb.html.

Cost of Thor Instrumented Leg

    The costs associated with specifying the use of Thor-Lx or Thor-
FLx/HIIIr lower legs in vehicle crash tests may be broken down as 
follows: (1) The cost of the legs themselves; and (2) the data 
acquisition costs (per crash test). NHTSA estimates the procurement 
cost to be approximately $52,600 per pair for both the 50th percentile 
male and 5th percentile female dummies. Because the agency does not 
believe that many vehicle manufacturers already have acquired these 
legs, it is reasonable to

[[Page 22384]]

assume that many, if not most, vehicle manufacturers would need to 
purchase them. With respect to the data acquisition costs, the agency 
estimates that each test utilizing the Thor-Lx/Thor-FLx lower legs 
would cost approximately $2,600 per dummy per crash test, assuming use 
of the upper and lower load cells, knee shear displacement, and ankle 
rotation data channels.

Performance of Instrumented Lower Leg Assemblies

    The agency has conducted a series of static and dynamic laboratory 
and vehicle crash tests to evaluate the performance of the HIII/Denton-
50M, HIII/Denton-5F, Thor-Lx/HIIIr, and Thor-FLx/HIIIr. These tests 
allow a direct comparison between the HIII/Denton-50M and the Thor-Lx/
HIIIr and between the HIII/Denton-5F and the Thor-FLx/HIIIr. In 
laboratory tests, the Thor-Lx/HIIIr and the Thor-FLx/HIIIr exhibit more 
biofidelic, or human-like, responses than the HIII/Denton-50M and the 
HIII/Denton-5F. The significance of this difference in biofidelity and 
the need for design sophistication to predict the risk of injury are 
the most important issues that the agency hopes to resolve with 
comments from end users and others.

Laboratory Tests

    The agency conducted the following laboratory calibration type 
tests and sled tests to evaluate the performance of the Denton and Thor 
lower leg assemblies per procedures set forth in Sections 3 and 4 of 
the Technical Report: (1) A quasi-static ankle motion test; (2) two 
pendulum impact tests (one on the ball of the foot and the other on the 
heel of the foot); and (3) a series of eight sled tests.

Quasi-Static Ankle Motion Tests

    In the quasi-static ankle motion test, the tibia of the 
instrumented leg is held rigidly while the foot is rotated in four 
directions (dorsiflexion, plantarflexion, inversion, and eversion). 
This test was performed on two HIII/Denton-50 legs, four Thor-Lx/HIIIr 
legs, two HIII/Denton-5F legs, and four Thor-FLx/HIIIr legs. Each ankle 
was tested four times under identical test conditions, yielding a mean 
value for each of the four directions. Both the Denton and the Thor 
legs exhibited repeatable performance. The mean response values were 
plotted on a graph and compared to the biofidelic specifications for 
each directional test as shown in Figures 3-1 through 3-8 of the 
Technical Report. The results indicate that the Thor-Lx/HIIIr and Thor-
FLx/HIIIr exhibit a response that is closer to biofidelic 
specifications than the HIII/Denton-50M and HIII/Denton-5F. Additional 
details regarding the test procedures and test results may be found in 
Section 3 and Appendix 3 of the Technical Report.

Pendulum Impact Tests

    Two different pendulum impact test series were conducted on both 
leg designs. The first test, the ball of foot impact test, examined the 
dynamic dorsiflexion response of the ankle assembly. The second test, 
the heel of foot impact test, examined the compliance of the foot flesh 
and tibia. These tests were performed on two HIII/Denton-50 legs, four 
Thor-Lx/HIIIr legs, two HIII/Denton-5F legs, and four Thor-FLx/HIIIr 
legs. Each lower leg assembly was tested four times under identical 
test conditions. In these pendulum impact tests, both the Denton and 
Thor lower leg assemblies exhibited repeatable performance and no 
structural issues were noted. A full description of the test procedures 
and test results may be found in Section 3.2 and Appendix 3 of the 
Technical Report.

Sled Tests

    A series of eight sled tests were conducted by the University of 
Virginia to evaluate the performance of the Thor lower leg assemblies 
relative to the Denton lower leg assemblies. Two of the tests, designed 
to simulate the New Car Assessment Program (NCAP) 56 kilometer per hour 
full-frontal crash conditions, were conducted using a Ford Taurus floor 
pan configuration with an intruding toeboard. Six tests, designed to 
simulate the European Union (EU) 40 percent offset frontal crash test 
conditions (although at 56 kilometers per hour rather than at 60 
kilometers per hour because of concerns about the structural integrity 
of the sled at 60 kilometers per hour), were conducted using a Dodge 
Neon floor pan configuration with an intruding toeboard. A full 
description of the test procedures and test results may be found in 
Section 4 and Appendix 4 of the Technical Report.
    These tests were designed to determine: (1) The effects of leg 
design on the peak femur response values; (2) the differences in other 
lower extremity response values between the two designs; (3) the 
effects of leg design on the upper body response values; (4) the 
repeatability of dummy response values; and (5) durability of the leg 
design. With respect to the effects of leg design on the peak femur 
response values, the tests revealed a difference in right femur 
response values between the HIII/Denton-50M and the Thor-Lx/HIIIr. The 
right femur response values for the HIII/Denton-50M were higher than 
those of the Thor-Lx/HIIIr. Differences were also noted between other 
lower extremity response values of the Denton and Thor lower leg 
assemblies.
    The observed differences, in the judgment of the University of 
Virginia's researchers, were attributable to differences in the Thor-
Lx's anterior geometry and kinematic response due to the Thor-Lx 
continuous joint stop. Although both the right femur and other lower 
extremity response values were higher for the Denton lower leg 
assemblies than the Thor lower leg assemblies, we consider these 
differences to be relatively insignificant when compared to the much 
higher injury limit values. As to the upper body response values, the 
recorded values were very similar for both the Denton and Thor 50th 
percentile male and 5th percentile female dummies indicating that 
differences in the designs of the lower legs have minimal influence on 
the rest of the dummy responses. As to repeatability, in both the full 
frontal and offset-frontal sled tests, the test-to-test repeatability 
of the Denton and Thor lower leg assemblies was found to be generally 
acceptable. Finally, with respect to durability, neither the Denton nor 
the Thor lower leg assemblies experienced any structural failures in 
the sled tests.

Vehicle Crash Tests

    The agency conducted 16 vehicle crash tests allowing assessment of 
the performance of paired 50th percentile male and 5th percentile 
female Hybrid III dummies with Denton and Thor-(F)Lx lower leg 
assemblies. Four vehicle models were used: the 1996 Toyota Camry, the 
2000 Nissan Altima, the 1998 Dodge Neon, and the 2000 Subaru Legacy. In 
these tests, a Hybrid III 50th percentile male or 5th percentile female 
dummy outfitted with either Denton or Thor instrumented lower legs was 
seated in the driver's position and the vehicle was crashed into an EU 
deformable barrier at approximately 60 and 64 kilometers per hour with 
40 percent of the vehicle's frontal structure engaging the barrier. A 
full description of the test procedures and test results may be found 
in Section 5 and Appendix 5 of the Technical Report.
    Such offset frontal crash tests generally produce significant 
intrusion of the toepan, thereby allowing for measurement of forces 
exerted on the lower extremities. Significant differences were noted 
with respect to the response values of the Thor and Denton lower leg 
assemblies in these

[[Page 22385]]

crash tests. The response values of the Thor-Lx/HIIIr and Thor-FLx/
HIIIr exceeded the foot and ankle preliminary injury limits in the 
vehicle crash tests, thus predicting a higher potential for foot and 
ankle injuries than tibia shaft fractures. In addition, the foot and 
ankle response values of the Thor-FLx/HIIIr were higher than those of 
the Thor-Lx/HIIIr, thus predicting a higher incidence of foot and ankle 
injuries in small women than in mid-sized men. The same differences 
between the female and male versions of the Denton leg could not be 
observed because it is not equipped to measure ankle rotation. Real-
world crash data indicate that ankle and foot injuries are more common 
than leg shaft fractures and that women are at greater risk of 
sustaining lower limb injuries than men. Therefore, it appears that the 
Thor lower leg assemblies are better able to predict the location of 
lower extremity injuries in real-world crashes than the Denton lower 
leg assemblies.

Questions for Public Comment

    The agency believes that lower extremity injuries are a serious and 
pervasive safety problem. They frequently result in significant pain, 
disability, and economic cost. The agency believes that these human and 
economic costs can be significantly reduced by enhancing vehicles' 
crashworthiness and occupant protection systems.
    In order to evaluate the effectiveness of particular designs in 
accomplishing this goal, however, the dummies used in vehicle crash 
tests must be equipped with appropriately instrumented lower limbs that 
will help predict the severity and extent of lower limb injuries. As 
noted above, two different leg designs are available for this purpose: 
the HIII/Denton legs and the Thor-(F)Lx//HIIIr. To aid the agency in 
determining which of the two leg designs would better facilitate the 
design and manufacture of occupant compartments that minimize the 
severity and extent of lower limb injuries, the agency is seeking 
comments on the following issues:

Experience With Instrumented Legs

    (1) Please indicate how many years of experience, if any, you have 
had in using instrumented legs to improve lower leg injury protection 
and describe that experience.
    (2) Please provide detailed information on any experience you have 
had in using the following instrumented lower legs:
    a. Thor-Lx legs;
    b. HIII/Denton legs;
    c. Other.
    (3) The lower limb consists of the following component parts: 
femur, knee, tibia plateau, tibia, ankle, foot, and pelvis as an 
attachment bone for the femur. Please rate each of these component 
parts in terms of the relative importance you place on it for injury 
reduction purposes using a 5 (five) to indicate a high degree of 
importance and a 0 (zero) to indicate low or no importance. Please also 
explain the basis for each rating and how the injury risk for that 
anatomical area is determined.
    (4) Please provide an opinion, based on your experience, whether 
the availability of highly instrumented tibia, ankle, and foot (TAF) 
and knees (Ks) would facilitate the development of vehicles capable of 
reducing lower leg injuries. Please describe the key aspects of your 
experience that give rise to your opinion.
    (5) In your test experience, did use of either of the instrumented 
legs influence other crash test measurements, such as those for the 
head, neck, thorax, etc.?

Injury Assessment Goals

    (6) What are your vehicle design or performance goals for the 
minimization of lower limb injuries? Please cite the impact modes, 
restraint configurations, and collision speeds at which the lower legs 
tested in your vehicles begin to incur AIS2+ injuries.
    (7) Please provide a list of injury assessment measures that you 
employ to assure KsTAF protection. Please explain the basis for their 
selection, including a demonstration of how they correspond to field 
data.
    (8) What, in your opinion, is the minimum level of (KsTAF) 
instrumentation needed to allow accurate assessment of potential 
injuries?
    (9) Please provide the methodology, techniques, and procedures you 
currently use to identify and assess the KsTAF injuries.
    (10) Please describe fully the test conditions under which you 
perform KsTAF injury assessment, i.e., static and/or dynamic 
measurements; component and/or systems tests; crash intensities, 
directions, mathematical simulations, visual evidence, etc.
    (11) Please provide descriptions of the test tools and 
instrumentation that you employ for items 9 and 10.
    (12) Please provide typical response samples and test conditions 
from tibia/ankle/foot measurements that you are using to make injury 
reduction or injury risk assessments, and state why you think they are 
important.

Adequacy of Instrumented Legs To Assess the Injury Potential

    (13) Given that the instrumented HIII/Denton leg only measures the 
potential for tibia and malleolus fractures and not ankle injuries, if 
you prefer the HIII/Denton leg, please provide information on how you 
would address the reduction of ankle and foot injuries.
    (14) The Thor-Lx/HIIIr instrumented tibia is more elastic in axial 
loading and has a number of other more human-like features than the 
rigid HIII/Denton tibia. Please indicate which, if any, of those 
features are critical for your safety work, which would be desirable to 
have, and which would not be used. Please provide the rationale and 
reasons for your choices.
    (15) Please provide your views regarding the relative desirability 
and benefits of the instrumented lower legs having a higher degree of 
biofidelity and greater injury predicting capability, but more 
mechanical complexity vs. less biofidelity and less accurate injury 
protection, but a simpler design.
    (16) Would either or both of the instrumented lower leg designs be 
adequate for assessing injury risk if used in the full- and offset-
frontal crash tests specified in Federal Motor Vehicle Safety Standard 
No. 208?
    a. If not, what tests, test environments, and impact speeds would 
you recommend?
    b. If the current leg and foot placement procedures in Federal 
Motor Vehicle Safety Standard No. 208 are not appropriate for assessing 
the potential for KsTAF injuries, please recommend procedures that 
would provide proper assessment.
    (17) Please indicate the extent to which you believe that one or 
both of the instrumented lower legs are, or may be, useful to address 
brake pedal and clutch intrusion issues. If you believe that it is or 
may be useful, please provide details of dummy set-up and associated 
test procedures.
    (18) Which of the available ankle sensors should be specified for 
injury assessment purposes and why?
    (19) Which of the available foot sensors should be specified for 
injury assessment purposes and why?

Calibration/Certification

    (20) Should the agency specify calibration tests for instrumented 
lower legs to assure that they work correctly in the vehicle crash 
environment? Please provide details and a rationale for your 
recommendation.
    (21) Should certification specifications for the lower limbs be 
related to injury measurements and risk of injury levels?

[[Page 22386]]

    (22) How much overload capacity do you believe the instrumented 
lower legs should have before they begin to experience structural 
failures?

Lead Time Needs

    (23) Please indicate, and justify, your lead time needs to become 
familiar with and generate the required test data should the agency 
specify the use of the following instrumented lower legs in FMVSS No. 
208 crash testing:
    a. HIII/Denton legs;
    b. Thor-Lx/HIIIr legs;
    c. Other (described in your response to question 2(c) above).

Costs

    (24) Please provide an itemized estimate of expected additional 
test costs (equipment, calibration, additional channels) if the agency 
specified use of the HIII/Denton or Thor(F)Lx-HIIIr legs for:
    a. FMVSS No. 208;
    b. NCAP.
    (25) Will the benefits of measuring and collecting this additional 
data be worth the additional costs?

International Harmonization

    (26) Please provide your views on the extent to which international 
harmonization of the instrumented leg should be a factor in the 
agency's decision-making process. How should the desire for 
harmonization be weighed against the overriding factor of safety and 
against other relevant factors?

Rulemaking Analyses and Notices

Executive Order 12866 and DOT Regulatory Policies and Procedures

    This advance notice was not reviewed under Executive Order 12866 
and under the Department of Transportation's regulatory policies and 
procedures.
    This notice primarily addresses the possibility of proposing to 
amend 49 CFR part 572 by adding design and performance specifications 
for instrumented lower legs that can be fitted to crash test dummies 
and used in vehicle crash tests for assessing the injury potential to 
lower limbs in full- and offset-frontal vehicle collisions. If these 
amendments are ultimately proposed and adopted as final, they would 
affect only those businesses that choose to manufacture or test with 
dummies fitted with those legs. The amendments would not impose any 
requirements on anyone. The agency is planning to conduct a separate 
rulemaking proceeding in which the agency would propose to amend the 
Federal motor vehicle safety standards to specify the use of dummies 
fitted with these legs in crash testing.
    For these reasons, it does not appear that this rulemaking, which 
concerns the incorporation of the instrumented lower legs into part 
572, would be significant. However, due to the preliminary nature of 
this document, NHTSA has limited current cost information that might be 
relevant to any potential changes. Accordingly, NHTSA is unable now to 
evaluate the economic impacts that this rulemaking might ultimately 
have.
    NHTSA will reassess this rulemaking in relation to the Executive 
Order, the DOT Regulatory Policies and Procedures, the Unfunded 
Mandates Reform Act of 1995 and other requirements for analyzing 
rulemaking impacts after using the information received in response to 
this advanced notice to select specific proposed amendments. To that 
end, the agency solicits comments, information, and data useful in 
assessing the impacts of making changes to the various requirements 
discussed in this document.

Comments

How Do I Prepare and Submit Comments?

    Your comments must be written and in English. To ensure that your 
comments are correctly filed in the Docket, please include the docket 
number of this document in your comments.
    Your comments must not be more than 15 pages long. (49 CFR 553.21). 
We established this limit to encourage you to write your primary 
comments in a concise fashion. However, you may attach necessary 
additional documents to your comments. There is no limit on the length 
of the attachments.
    Please submit two copies of your comments, including the 
attachments, to Docket Management at the address given above under 
ADDRESSES.
    You may also submit your comments to the docket electronically by 
logging onto the Dockets Management System Web site at http://dms.dot.gov. Click on ``Help & Information'' or ``Help/Info'' to obtain 
instructions for filing the document electronically.

How Can I Be Sure That My Comments Were Received?

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

How Do I Submit Confidential Business Information?

    If you wish to submit any information under a claim of 
confidentiality, you should submit three copies of your complete 
submission, including the information you claim to be confidential 
business information, to the Chief Counsel, NHTSA, at the address given 
above under FOR FURTHER INFORMATION CONTACT. In addition, you should 
submit two copies, from which you have deleted the claimed confidential 
business information, to Docket Management at the address given above 
under ADDRESSES. When you send a comment containing information claimed 
to be confidential business information, you should include a cover 
letter setting forth the information specified in our confidential 
business information regulation. (49 CFR part 512.)

Will the Agency Consider Late Comments?

    We will consider all comments that Docket Management receives 
before the close of business on the comment closing date indicated 
above under DATES. To the extent possible, we will also consider 
comments that Docket Management receives after that date. If Docket 
Management receives a comment too late for us to consider it in 
developing a proposal (assuming that one is issued), we will consider 
that comment together with the comments on the proposal.

How Can I Read the Comments Submitted by Other People?

    You may read the comments received by Docket Management at the 
address given above under ADDRESSES. The hours of the Docket are 
indicated above in the same location.
    You may also see the comments on the Internet. To read the comments 
on the Internet, take the following steps:
    1. Go to the Docket Management System (DMS) Web page of the 
Department of Transportation(http://dms.dot.gov/).
    2. On that page, click on ``search.''
    3. On the next page (http://dms.dot.gov/search/), type in the four-
digit docket number shown at the beginning of this document. Example: 
If the docket number were ``NHTSA-1998-1234'', you would type ``1234''. 
After typing the docket number, click on ``search''.
    4. On the next page, which contains docket summary information for 
the docket you selected, click on the desired comments. You may 
download the comments. Although the comments are

[[Page 22387]]

imaged documents, instead of word processing documents, the ``pdf'' 
versions of the documents are word searchable.
    Please note that even after the comment closing date, we will 
continue to file relevant information in the Docket as it becomes 
available. Further, some people may submit late comments. Accordingly, 
we recommend that you periodically check the Docket for new material.

List of Subjects in 49 CFR Part 572

    Motor vehicle safety, Incorporation by reference.

    Issued: April 30, 2002.
Stephen R. Kratzke,
Associate Administrator for Safety Performance Standards.
[FR Doc. 02-11050 Filed 5-2-02; 8:45 am]
BILLING CODE 4910-59-P