[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
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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
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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