[Federal Register: May 1, 2002 (Volume 67, Number 84)]
[Proposed Rules]
[Page 21805-21836]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr01my02-27]
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Part II
Department of Transportation
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National Highway Traffic Safety Administration
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49 CFR Part 571
Federal Motor Vehicle Safety Standards; Child Restraint Systems;
Proposed Rule
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DEPARTMENT OF TRANSPORTATION
National Highway Traffic Safety Administration
49 CFR Part 571
[Docket No. NHTSA-02-11707]
RIN 2127-AI34
Federal Motor Vehicle Safety Standards; Child Restraint Systems
AGENCY: National Highway Traffic Safety Administration (NHTSA),
Department of Transportation.
ACTION: Notice of proposed rulemaking (NPRM).
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SUMMARY: This document proposes a number of revisions to the Federal
safety standard for child restraint systems, including proposals for
incorporating improved test dummies and updated procedures used to test
child restraints, new or revised injury criteria to assess the dynamic
performance of child restraints, and extension of the standard to apply
it to child restraints recommended for use by children up to 65 pounds.
This action is intended to make child restraints even more effective in
protecting children from the risk of death or serious injury in motor
vehicle crashes. This proposal is being issued in response to the
Transportation Recall Enhancement, Accountability and Documentation Act
of 2000, which directed NHTSA to initiate a rulemaking proceeding for
the purpose of improving the safety of child restraints.
DATES: You should submit your comments early enough to ensure that
Docket Management receives them not later than July 1, 2002.
ADDRESSES: You may submit your comments in writing to: Docket
Management, Room PL-401, 400 Seventh Street, SW., Washington, DC,
20590. Alternatively, you may submit your comments electronically by
logging onto the Docket Management System 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 Docket Management at 202-366-9324. You may visit
the Docket from 10:00 a.m. to 5:00 p.m., Monday through Friday.
FOR FURTHER INFORMATION CONTACT: For non-legal issues, you may call
Mike Huntley of the NHTSA Office of Crashworthiness Standards, at 202-
366-0029.
For legal issues, you may call Deirdre Fujita of the NHTSA Office
of Chief Counsel, at 202-366-2992.
You may send mail to both of these officials at the National
Highway Traffic Safety Administration, 400 Seventh St., SW, Washington,
DC, 20590.
SUPPLEMENTARY INFORMATION:
Table of Contents
I. Executive Summary
II. Background
III. Existing Requirements of Standard No. 213
IV. ANPRM on Side Impact Protection
V. Agency Proposals
a. Updated Bench Seat
1. Introduction
2. Post-TREAD Rulemaking Support Program
3. Features That Should Be Changed
i. Bottom Seat Cushion Angle
ii. Seat Back Angle
iii. Seat Belt Anchors
iv. Fixed Seat Back
4. Features That Need Not Be Changed
i. Bottom Seat Cushion Length
ii. Seat Back Height
iii. Test Bench Floor
5. What About Cushion Stiffness?
b. Crash Pulse
1. The Current Crash Pulse
2. The Crash Pulse Is Not Overly Severe
3. Adjusting the Corridors of the Pulse
c. Improved Child Test Dummies
1. CRABI, Hybrid III Dummies
i. Replacing Current Dummies
ii. Retaining the Criteria Used to Determine Which Dummy Is Used
in Compliance Tests
iii. Conditioning the Dummies
2. Using A Weighted 6-Year-Old Dummy
i. Development of the 10-Year-Old Dummy Is a Long-Term Measure
ii. A Weighted 6-Year-Old Dummy Is a Feasible Short-Term
Alternative
d. Expanding The Applicability Of the Standard to 65 Lb
e. New Or Revised Injury Criteria
1. Scaled Injury Criteria
i. Head Injury
A. Should HIC Duration Be Limited To 15 Milliseconds?
B. Test Data
ii. Thoracic Injury
A. Chest Acceleration
B. Chest Deflection
C. Weighted 6-Year-Old Dummy
D. Test Data
iii. Neck Injury
iv. Tabulated Data
2. Static Testing Criteria
VI. Proposed Effective Dates
VII. Child Passenger Safety Plan and Other Issues of the TREAD Act
a. Comments on Possible Rulemaking
b. Rear-Impact Test
c. Child Restraints in NCAP Tests
VIII. Rulemaking Analyses and Notices
a. Executive Order 12866 (Regulatory Planning and Review) and
DOT Regulatory Policies and Procedures
b. Regulatory Flexibility Act
c. Executive Order 13132 (Federalism)
d. Unfunded Mandates Reform Act
e. National Environmental Policy Act
f. Executive Order 12778 (Civil Justice Reform)
g. Plain Language
h. Paperwork Reduction Act
i. National Technology Transfer and Advancement Act
IX. Submission of Comments
I. Executive Summary
This document proposes a number of revisions to Federal Motor
Vehicle Safety Standard No. 213, ``Child Restraint Systems'' (49 CFR
571.213). The proposed revisions would incorporate five elements into
the standard: (a) An updated bench seat used to dynamically test add-on
child restraint systems; (b) a sled pulse that provides a wider test
corridor; (c) improved child test dummies; (d) expanded applicability
to child restraint systems recommended for use by children weighing up
to 65 pounds; and (e) new or revised injury criteria to assess the
dynamic performance of child restraints. This proposal follows up on
the agency's announcement in its November 2000 Draft Child Restraint
Systems Safety Plan (Docket NHTSA-7938) that the agency will be
undertaking rulemaking on these and other elements of Standard No. 213
(65 FR 70687; November 27, 2000). The proposal is also issued in
response to the mandate in the Transportation Recall Enhancement,
Accountability and Documentation Act (the TREAD Act) (November 1, 2000,
Pub. L. 106-414, 114 Stat. 1800) to initiate a rulemaking for the
purpose of improving the safety of child restraints.
Section 14(a) of the TREAD Act mandates that the agency ``initiate
a rulemaking for the purpose of improving the safety of child
restraints, including minimizing head injuries from side impact
collisions.'' Section 14(b) identifies specific elements that the
agency must consider in its rulemaking. The Act gives the agency
substantial discretion over the decision whether to issue a final rule
on the specific elements. Section 14(c) specifies that if the agency
does not incorporate any element described in section 14(b) in a final
rule, the agency shall explain in a report to Congress the reasons for
not incorporating the element in a final rule.
In response to section 14, the agency comprehensively examined
possible ways of revising and updating its child restraint standard.
Today's proposal is substantially based on a combination of pre- and
post-TREAD Act agency activities, including extensive testing of child
restraints and dummies by NHTSA's Vehicle Research & Test Center and by
the agency in its New Car
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Assessment Program, and on evaluations of vehicle seat assemblies and
pulses. The proposal is also based on data analysis, as well as agency
review of existing global research papers and international standards.
We have also taken into consideration submissions by the public in
response to the agency's Safety Plan and sought an exchange of ideas
with child restraint manufacturers as to the research being conducted
in response to the TREAD Act, meeting with them in February 2001. There
are a number of technical reports in the docket to which this NPRM will
refer to from time to time in support of the proposals.
In an advance notice of proposed rulemaking published concurrently
with today's document, we are seeking public comments on the agency's
work on developing a possible side impact protection standard for child
restraint systems and on possible refinements to the approach we have
taken thus far. In its review of the child restraint standard, NHTSA
placed particular emphasis on improving the ability of child restraints
to provide protection in side impact crashes. Although we have
conducted extensive testing and analysis over the past year aimed at
providing additional side impact protection for children in child
restraints, there are many unknowns. We seek comment on the suitability
of the test procedures we are considering, on appropriate injury
criteria for children in side impacts, on cost beneficial
countermeasures, and on other issues. The agency anticipates that
comments to the advance notice will help us assess the benefits and
costs of a side impact rulemaking, which will help us decide whether to
issue a notice of proposed rulemaking in the near future and/or
identify the work that needs to be done.
The proposed updates to the seat assembly are based on studies that
NHTSA contracted to have done in response to the TREAD Act. This NPRM
proposes the following changes: the seat bottom cushion angle would be
increased from 8 degrees off horizontal to 15 degrees; the seat back
cushion angle would be increased from 15 degrees off the vertical to 22
degrees; the spacing between the anchors of the lap belt would be
increased from 222 millimeters (mm) to 392 mm in the center seating
position and from 356 mm to 472 mm in the outboard seating positions;
and the seat back of the seat assembly would be changed, from a
flexible seat back to one that is fixed, to represent a typical rear
seat in a passenger car.
The proposed changes to the sled pulse are based on studies
conducted in response to the TREAD Act. We propose to widen the test
corridor to make it easier for more test facilities to reproduce. The
wider corridor extends the pulse from 80 milliseconds (ms) to
approximately 90 ms in duration. The expanded corridor would not reduce
the stringency of the test, and would also make it easier to conduct
compliance tests at speeds closer to 30 mph.
This document proposes two initiatives toward enhancing the use of
test dummies in the evaluation of child restraints under Standard No.
213. NHTSA proposes to replace some of the existing dummies with the
new 12-month-old Child Restraint Air Bag Interaction (CRABI) dummy, and
the state-of-the art Hybrid III 3- and 6-year-old dummies. NHTSA also
proposes testing child restraints for older children with a weighted 6-
year-old dummy (i.e., a Hybrid III 6-year-old dummy to which weights
have been added). The total weight of the dummy would be 62 lb. The
weighted dummy would be used to test child restraints that are
recommended for children weighing 50 to 65 lb, and is viewed as an
interim measure until such time as the Hybrid III 10-year-old dummy
becomes available.
The proposal to extend Standard No. 213 to child restraint systems
for children who weigh 65 lb or less is based on the proposal to test
restraints recommended for children weighing over 50 lb with the
weighted 6-year-old dummy. The availability of that dummy makes it
possible to extend the standard and evaluate the performance of the
added restraints.
The proposal to use the new and scaled injury criteria of Standard
No. 208 is based on research that the agency did in the advanced air
bag rulemaking, as well as NCAP and sled testing done in response to
the TREAD Act. The scaled head injury criterion limits from the
Standard No. 208 rulemaking are proposed herein for Standard No. 213,
as well as the chest deflection and acceleration limits. The Nij neck
criterion would also be added to Standard No. 213, but without the
limits on axial force. For Standard No. 208, the agency originally
proposed Nij without limits on axial force. However, the Alliance of
Automotive Manufacturers persuaded the agency to incorporate more
conservative axial force limits for the out-of-position air bag loading
environment. 65 FR 30717, 30718; May 12, 2000. Children in child
restraints are correctly positioned and not sustaining neck injuries
such as those associated with exposure to severe out-of-position air
bag loading. Therefore, the agency is proposing that Nij without limits
on axial force be added to Standard No. 213.
NHTSA has examined the benefits and costs of these proposed
amendments, wishing to adopt only those amendments that contribute to
improved safety, and mindful of the principles for regulatory
decisionmaking set forth in Executive Order 12866, Regulatory Planning
and Review. Its efforts to do so, however, have been limited by several
factors. Two factors stand out. One is the limited time allowed by the
schedule specified in the TREAD Act for initiating and completing this
rulemaking. That has limited the amount and variety of information that
the agency could obtain and testing that the agency could conduct to
examine the efficacy of possible countermeasures under consideration
and the effects of the various proposed amendments on child restraint
performance. The other is the lack of specific accident data on
children in motor vehicle crashes generally. For example, there is
little available data on neck injury in children involved in motor
vehicle crashes. Together, these limitations have made it difficult to
assess and compare the benefits and costs of this rulemaking.
NHTSA estimates that the proposal to use the new and scaled injury
criteria of Standard No. 208 would prevent an estimated 3-5 fatalities
and 5 MAIS 2-5 non-fatal injuries for children ages 0-1 annually. In
addition, the proposal would save 1 fatality and mitigate 1 MAIS 2-5
injury in the 4-to 6-year-old age group annually. The agency does not
believe that updating the seat assembly and revising the crash pulse
would affect dummy performance to an extent that benefits would accrue
from such changes. Research will be conducted later this year to assess
the effects of such changes on dummy performance.
At this time, NHTSA has not identified countermeasures to improve
child restraint performance in frontal tests that would allow child
restraint manufacturers to meet the proposed neck injury criterion.
Consequently, we were unable to estimate the costs of such
countermeasures. Comments are requested on possible countermeasures and
their costs. The proposal to use new dummies in compliance tests,
including testing with a weighted 6-year-old dummy, could result in
increased testing costs for manufacturers that want to certify their
restraints using the tests that NHTSA will use in compliance testing.
NHTSA estimates that use of the new dummies and other changes to the
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test procedure would add testing costs of $2.72 million. We believe
that those changes would not result in redesign of child restraints.
II. Background
The lack of occupant restraint use by motorists is a significant
factor in most fatalities resulting from motor vehicle crashes. Of the
31,910 passenger vehicle occupants killed in 2000, over half (55
percent) were unrestrained. Forty-three percent of the 1,079 child
occupant fatalities, ages 0 through 10 years old, were unrestrained.
For child occupants less than 5 years old, 36 percent of the 529
fatalities were unrestrained.
Of the 2,938,000 passenger vehicle occupants injured in crashes in
2000, only 14 percent (409,000) were reported as unrestrained. The
rates are about the same for child occupants. For children ages 0-10
years old, approximately 165,000 were injured in motor vehicle traffic
crashes in 2000, and 13 percent (18,800) of these children were
unrestrained. Of the 67,000 child occupants less than 5 years of age
who were injured, 10 percent (6,500) were unrestrained.
Child restraints are highly effective in reducing the likelihood of
death and or serious injury in motor vehicle crashes. NHTSA estimates
(``Revised Estimates of Child Restraint Effectiveness,'' Hertz, 1996)
that for children less than one-year-old, a child restraint can reduce
the risk of fatality by 71 percent when used in a passenger car and by
58 percent when used in a pickup truck, van, or sport utility vehicle
(light truck). Child restraint effectiveness for children between the
ages 1 to 4 years old is 54 percent in passenger cars and 59 percent in
light trucks.
Notwithstanding the effectiveness of child restraints certified to
Standard No. 213, the agency is continuing to examine whether the
safety of children in child restraints can be enhanced even further. In
2000, 256 child occupants under 5 years of age were killed while
restrained in child restraints, and another 34,600 were injured.
Today's NPRM is part of an effort to reduce these numbers.
On November 27, 2000, we published a planning document that defined
our vision for enhancing child passenger safety over the next 5 years
(65 FR 70687). The plan contained our views on implementing three
strategies for enhancing the safety of child occupants from birth
through age 10: increasing restraint use; improving the performance and
testing of child restraints; and improving mechanisms for providing
safety information to the public. The agency requested comments on the
plan and received suggestions on the various initiatives (Docket NHTSA
7938).
Many commenters responded to the second of the three strategies,
making suggestions as to how they believed Standard No. 213 should be
improved to further enhance child restraint performance. There was
general concurrence with the agency's plan to undertake rulemaking with
regard to the five elements included today in this NPRM. There was no
objection to the agency's then-announced intention to improve side
impact protection as a measure that would be pursued internationally in
concert with other government and industry bodies. However, it was
apparent from the few comments we received on the subject that those
commenters considered it to be a long-term project requiring several
years of research and development.
After NHTSA completed its draft plan, but before it published the
plan in the Federal Register, the TREAD Act was enacted on November 1,
2000. Sections 14 of the TREAD Act directed NHTSA to initiate a
rulemaking for the purpose of improving the safety of child restraints
by November 1, 2001, and to complete it by issuing a final rule or
taking other action by November 1, 2002. The relevant provisions in
Sections 14 are as follows:
(a) In General. Not later than 12 months after the date of
enactment of this Act, the Secretary of Transportation shall
initiate a rulemaking for the purpose of improving the safety of
child restraints, including minimizing head injuries from side
impact collisions.
(b) Elements for Consideration. In the rulemaking required by
subsection (a), the Secretary shall consider--
(1) whether to require more comprehensive tests for child
restraints than the current Federal motor vehicle safety standards
requires, including the use of dynamic tests that--
(A) replicate an array of crash conditions, such as side-impact
crashes and rear-impact crashes; and
(B) reflect the designs of passenger motor vehicles as of the
date of enactment of this Act;
(2) whether to require the use of anthropomorphic test devices
that--
(A) represent a greater range of sizes of children including the
need to require the use of an anthropomorphic test device that is
representative of a ten-year-old child; and
(B) are Hybrid III anthropomorphic test devices;
(3) whether to require improved protection from head injuries in
side-impact and rear-impact crashes;
(4) how to provide consumer information on the physical
compatibility of child restraints and vehicle seats on a model-by-
model basis;
(5) whether to prescribe clearer and simpler labels and
instructions required to be placed on child restraints;
(6) whether to amend Federal Motor Vehicle Safety Standard No.
213 (49 CFR 571.213) to cover restraints for children weighing up to
80 pounds;
(7) whether to establish booster seat performance and structural
integrity requirements to be dynamically tested in 3-point lap and
shoulder belts;\1\
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\1\ Standard No. 213 currently requires booster seats to be
dynamically tested in 3-point (lap and shoulder) belts. As such, the
agency is taking no action with respect to this provision of the
TREAD Act. [Footnote added.]
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(8) whether to apply scaled injury criteria performance levels,
including neck injury, developed for Federal Motor Vehicle Safety
Standard No. 208 to child restraints and booster seats covered by in
[sic] Federal Motor Vehicle Safety Standard No. 213; and
(9) whether to include [a] child restraint in each vehicle crash
tested under the New Car Assessment Program.
(c) Report to Congress. If the Secretary does not incorporate
any element described in subsection (b) in the final rule, the
Secretary shall explain, in a report to the Senate Committee on
Commerce, Science, and Transportation and the House of
Representatives Committee on Commerce submitted within 30 days after
issuing the final rule, specifically why the Secretary did not
incorporate any such element in the final rule.
(d) Completion. Notwithstanding any other provision of law, the
Secretary shall complete the rulemaking required by subsection (a)
not later than 24 months after the date of the enactment of this
Act.
Each of the initiatives contemplated by the TREAD Act as possible
upgrades to Standard No. 213 were included in the agency's plan as
possible candidates for rulemaking to enhance the performance of child
restraint systems. \2\ Notwithstanding the effectiveness of child
restraints certified to Standard No. 213, the thrust of the 5-year plan
was to consider possible rulemaking that could enhance the performance
of child restraints even further. Enhancements were considered in terms
of improved crash protection and in terms of increased usability of the
restraints so that misuse is reduced. At the same time, we believed
then, and continue to do so now, that in making regulatory
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decisions on possible safety enhancements, the agency must bear in mind
the consumer acceptance of cost increases.
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\2\ In addition, Section 14 of the TREAD Act required an NPRM to
establish a child restraint safety rating consumer information
program to provide consumers information for use in the purchase of
child restraints. The NPRM was issued on October 29, 2001, and
published November 6, 2001 (66 FR 56146, 66 FR 56048). Further, on
October 29, 2001, the agency issued an NPRM on Standard No. 213's
labeling and owner's manual requirements that responds to section
14(b)(5) of the Act. 66 FR 55623, November 2, 2001. The Act also
required a study on the use and effectiveness of booster seats and a
5-year strategic plan to reduce, by 25 percent, deaths and injuries
caused by failure to use the appropriate booster seat in the 4-to 8-
year-old age group.
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Weighing all these factors, the agency has tentatively decided that
safety enhancements are warranted in the aspects of the child1
restraint standard discussed below in section IV.
III. Existing Requirements of Standard No. 213
The following discussion summarizes current provisions in Standard
No. 213 relating to the performance of child restraint systems.
1. The performance of a child restraint system is evaluated in
dynamic tests involving a 30 mph velocity change, which is
representative of a severe crash. Each child restraint is tested while
attached to a standardized seat assembly. Restraints are tested while
attached to the standard seat assembly by various means. The restraint
system is anchored to a test seat with a lap belt only, or a lap/
shoulder belt if the restraint system is a booster seat designed for
these belts. In another test, the child restraint is required to meet
more demanding requirements with respect to the permissible forward
motion of the dummy's head, which is typically accomplished by use of a
tether attached to the top of the child restraint. Beginning in 2002,
child restraints will also be subjected to frontal crash simulations
when anchored to the test seat assembly by a new child restraint
anchorage system (49 CFR 571.225).\3\ Built-in child seats are
evaluated by crash testing the vehicle they are built into, or by
simulating a crash with the built-in seat dynamically tested with parts
of the vehicle surrounding it.
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\3\ Standard No. 225 requires motor vehicle manufacturers to
provide vehicles equipped with the child restraint anchorage systems
that are standardized and independent of the vehicle seat belts. The
new independent system has two lower anchorages, and one upper
anchorage. Each lower anchorage includes a rigid round rod or
``bar'' unto which a hook, a jaw-like buckle or other connector can
be snapped. The bars are located at the intersection of the vehicle
seat cushion and seat back. The upper anchorage is a ring-like
object to which the upper tether of a child restraint system can be
attached. (The system is widely known as the ``LATCH system,'' an
acronym developed by manufacturers and retailers for ``lower anchors
and tether for children.'') The LATCH system is required to be
installed at two rear seating positions. In addition, a tether
anchorage is required at a third position. By requiring an easy-to-
use anchorage system that is independent of the vehicle seat belts,
NHTSA's standard makes possible more effective child restraint
installation and thereby increases child restraint effectiveness and
child safety. The standard is estimated to save 36 to 50 lives
annually, and prevent 1,231 to 2,929 injuries. See 64 FR 10786;
March 5, 1999.
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2. To protect the child, limitations are set on the amount of force
that can be exerted on the head and chest of a child test dummy during
the dynamic testing. (S5.1.2 of Standard No. 213). To reduce the
possibility of injury that child occupants in child restraint systems
may incur if they contact vehicle interior surfaces during a crash,
limitations are also set on the amount of frontal head and knee
excursions that can be experienced by the test dummy. To prevent a
child from being ejected from rearward-facing restraints (e.g., infant
restraints), limitations are set on the amount that such restraints can
tip forward (S5.1.4 of Standard No. 213).
3. During dynamic testing, no load-bearing or other structural part
of any child restraint system may separate so as to create jagged edges
that could cut and injure a child. If the child restraint has
adjustable positions, it may not shift positions if doing so could
potentially catch a child's limbs between the shifting parts or allow
the child to ``submarine'' (i.e., allow the child to slide down and out
of the restraint during a crash) (S5.1.1 of Standard No. 213).
4. To prevent injuries to children during crashes from contact with
the surfaces of the child restraint itself, the standard specifies
requirements for the size and shape of those surfaces. In addition,
protective padding requirements are set for restraints designed for use
by infants (S5.2 of Standard No. 213). The standard specifies a minimum
surface area for those surfaces that support the side of the child's
torso. Each surface must be flat or concave and have a continuous
surface of not less than 24 square inches for systems recommended for
children weighing 20 lb or more, or 48 square inches for systems
recommended for children weighing less than 20 lb (S5.2.2.1(b)).
5. The belts, buckles, and attachment hardware used in child
restraint systems have to meet abrasion and corrosion resistance
requirements (S5.4.1 and S5.4.2). Additionally, the belts in child
restraints must adjust to snugly fit occupants, not transfer any crash
loads from the vehicle to the child, and must restrain the child's
upper and lower torso (S5.4.3 of Standard No. 213).
6. The amount of force necessary to open belt buckles and release a
child from a restraint system is specified so that children will not be
able to unbuckle themselves, but adults will be able to do so quickly
and easily (S5.4.3.5 and S6 of Standard No. 213).
7. Information necessary for the proper use of the child restraint
system must be permanently labeled on the child restraint and presented
in an information booklet that accompanies the child restraint system.
The child restraint must also provide a special location or compartment
on the child restraint system in which the information booklet may be
permanently stored, so that the parent or other user of the child
restraint can always have available the necessary safety information
(S5.5 of Standard No. 213). Standard No. 213 also requires each child
restraint system to be accompanied by a postage-paid registration form
so that purchasers can register with the manufacturer and thereby be
directly notified in the event of a safety recall. Manufacturers must
retain the names and addresses of registrants for a period of six
years. (S5.8 of Standard No. 213; 49 CFR part 588).
8. Each material used in a child restraint system must meet the
flammability requirements of S4 of FMVSS No. 302 (49 CFR 571.302) (S5.7
of Standard No. 213).
9. Beginning September 1, 2002, child restraint systems must have
components permanently attached to them that will enable them to be
anchored to a new child restraint anchorage system that will be
standard on all new passenger vehicles. The vehicle anchorage system
consists of two bars that are at or close to the intersection of the
vehicle seat cushion and seat back, and a top tether anchorage located
typically (a) on the rear shelf below the rear window in passenger
cars, or (b) on the floor or on or under the seat structure of sport
utility vehicles and minivans. Child restraints will still be capable
of being anchored to the vehicle seat by the vehicle seat belts.
10. Child restraints certified for use in both motor vehicles and
aircraft must pass an additional test when attached to a representative
airplane seat, and provide additional information on the proper use of
the restraint system in an airplane seat (S8 of Standard No. 213).
IV. ANPRM on Side Impact Protection
In an advance notice of proposed rulemaking (ANPRM) published
concurrently with today's NPRM, we are seeking public comments on the
agency's work on developing a possible side impact protection standard
for child restraint systems and on possible refinements to the approach
we have taken thus far. In its review of the child restraint standard
in response to the TREAD Act, NHTSA placed particular emphasis on
improving the ability of child restraints to provide protection in side
impact crashes. Although we have conducted extensive testing and
[[Page 21810]]
analysis over the past year aimed at providing additional side impact
protection for children in child restraints, there are many unknowns.
We seek comment on the suitability of the test procedures we are
considering, on appropriate injury criteria for children in side
impacts, on cost beneficial countermeasures, and on other issues. The
agency anticipates that comments to the advance notice will help us
assess the benefits and costs of a side impact rulemaking, which will
help us decide whether to issue a notice of proposed rulemaking in the
near future and/or identify the work that needs to be done.
V. Agency Proposals
a. Updated Bench Seat
1. Introduction
This NPRM proposes to update the standard vehicle seat assembly
used in Standard No. 213's dynamic testing. The original seat assembly
was developed in the mid-1970's by the Highway Safety Research
Institute at the University of Michigan. The bench seat was based on
the configuration and performance parameters of the 1974 Chevrolet
Impala production front bench seat. Static and dynamic characteristics
of the production seat were modeled into the frame deformation and foam
stiffness of the standard seat.
NHTSA proposes to update the following features of the seat
assembly: the seat bottom cushion angle would be increased from 8
degrees off horizontal to 15 degrees; the seat back cushion angle would
be increased from 15 degrees off the vertical to 22 degrees; the
spacing between the anchors of the lap belt would be increased from 222
millimeters (mm) to 392 mm in the center seating position and from 356
mm to 472 mm in the outboard seating positions; and the seat back of
the seat assembly would be changed from a flexible seat back to one
that is fixed, to represent a typical rear seat in a passenger car.
Figures 1A, 1B and 1B' of Standard No. 213 would be revised to reflect
these changes, as would the drawing package of the seat assembly (SAS-
100-1000, with Addendum A, dated October 23, 1998) that is incorporated
by reference (see 49 CFR 571.5) into the standard.
This proposal is based on evaluations we have made regularly over
the years, and most recently this year in response to the TREAD Act, of
the need to update or improve the seat assembly used for testing child
restraints. There is no question that the seat assembly should be
representative of production seats to the extent possible so that a
child restraint's true performance in a crash can be assessed. However,
while to the extent possible it may be desirable for the seat assembly
to mirror production seats, our program work developing and evaluating
the standard seat assembly was guided by a number of additional
considerations. The seat assembly must be durable and must contribute
to obtaining repeatable and comparable test results for child
restraints. Meeting the performance requirements of Standard No. 213 on
the test seat should ensure that child restraints performed adequately
on the variety of different seats found in cars on the road. In
comparison to some vehicle seats, the test seat might present more
demanding test conditions, but this was acceptable if the test seat
were representative of many seats used in vehicles. Differences between
the standard seat assembly and production seats could be disregarded if
the differences did not affect child restraint performance on the seat.
The seat assembly did not need to conform to non-identical features
that were unlikely to have a confounding effect on child restraint
performance.
These considerations counseled against changing the seat assembly
significantly in the past. Child restraints were performing well in the
field. The few features that we thought could be updated, such as the
seat assembly's cushion angle and seat back angle, were not thought to
affect safety sufficiently to warrant use of the agency's limited
resources for that purpose. We were also concerned about possible cost
increases to child restraints that might occur as some manufacturers
passed on the costs of possibly having to retest all child restraints
on the market.
With the passage of section 14(b) of TREAD, Congress has presented
its belief that the seat assembly should be updated to reflect the
designs of production seats. We concur with considering the issue
further. We have identified a number of features of the present seat
assembly that could be updated, which are discussed below. Later this
year, NHTSA will undertake an assessment of what effect, if any, the
updated seat assembly might have on the performance of child
restraints.
2. Post-TREAD Rulemaking Support Program
In response to TREAD, NHTSA initiated a test program to assess seat
parameters of production seats, working with Veridian Engineering
(Veridian) and the U.S. Naval Air Warfare Center Aircraft Division at
Patuxent River, Maryland (PAX). Veridian gathered information on
geometry and stiffness of seats of vehicles tested in NHTSA's 2001 New
Car Assessment Program (NCAP). PAX analyzed the seat geometry data,
including seat cushion angle, seat back angle, seat cushion length,
seat back length, tether anchor locations, child restraint anchorage
system anchor locations, and seat belt locations. A report by PAX on
the project is available in the docket. This preamble provides an
overview of the results. Readers are referred to the report for a
detailed explanation of the methodology used in the test program, and
the results of each parameter, sorted by vehicle class.
To summarize the report, the research program analyzed the seat
geometries of 35 vehicles. Because of time constraints and the fact
that the test for determining force/deflection characteristics of the
vehicle seat is a destructive test (that is, a section of the seat
cushion had to be cut out and removed), the agency utilized vehicles
that had previously undergone testing in the agency's New Car
Assessment Program but whose rear seats had not been destroyed or
discarded. Every attempt was made to obtain vehicles from a range of
vehicle classes for evaluation. Of these vehicles, 19 were passenger
cars, 11 were SUVs, 4 were minivans, and 1 was a pickup truck. PAX
analyzed the various seat geometry measurements of the vehicles, by
seating position (outboard or middle) and vehicle class, and identified
some features of the bench that do not reflect current vehicle designs.
We have tentatively determined that a number of those features
should be changed, that some others need not be, and that a few
features (e.g., seat cushion stiffness) require further analysis before
we can decide whether we should change them. Generally, where there is
a notable difference between the existing seat assembly and the fleet,
the agency has proposed changing the seat assembly to make it more
representative of the existing vehicle fleet.
We request comments on the proposal, particularly with regard to
the latter category. NHTSA will be conducting further analyses of some
of the proposed changes, since the analyses could not be completed in
time for this NPRM. Information we obtain will be placed in the docket.
Further, later this year, NHTSA will be evaluating dynamically most of
the changes that we propose to make to the seat bench, to ensure that
these changes do not result in compromising the safety currently
afforded by child restraints. Results of this testing will be compared
to compliance test data of existing child restraints to evaluate the
effect of the changes. Comparison of these tests will
[[Page 21811]]
aid in the agency's decision regarding whether to adopt the proposed
changes in a final rule.
3. Features That Should Be Changed
i. Bottom Seat Cushion Angle
Currently, the seat assembly has a seat pan angle of 8 deg. off
horizontal. In the 35 vehicles surveyed, 77 seat pan angle measurements
were made of rear seats, from either the outboard position or the
center position, or if the vehicle had a third seating position, from
that position as well. PAX found that 39% of the seat pan angle
measurements were within 16 deg. to 20 deg. off horizontal and 35% of
the seat pan angle measurements fell within 11 deg. to 15 deg. of
horizontal. The test data show an average seat pan angle of 15.5 deg..
We have tentatively decided that the seat pan angle of the seat
assembly should be increased to 15 deg. off horizontal. A 15 deg. angle
would be in accordance with the bottom seat cushion angle specified by
ECE Regulation 44.
Comments are requested on the effect of this change on the
performance of child restraints in actual vehicles. In a September 18,
2000 petition for rulemaking, Ford Motor Company indicated that using
the ECE Regulation 44 seat cushion angle would solve a problem it has
found using the present seat assembly to test ``rear-facing child
restraint systems (CRS) equipped with rigid Lower Anchors and Tethers
for Children (LATCH) system attachments.'' Under Standard No. 213,
child restraints may use rigid attachments to connect to the lower
anchorage bars of LATCH systems, or may use non-rigid attachments (such
as those attached to the child restraint by webbing material). Ford
believed that the seat cushion angle of the seat assembly is driving
the design of rear-facing child restraints. Because the current seat
assembly is flatter than actual vehicle seats, when infant restraints
are installed on actual vehicle seats, the restraints are installed at
an overly steep angle. Ford stated that the overly steep angle can be
corrected in conventional restraints by tipping the restraint back and
placing a rolled towel under the base, near the seat bight. However, an
infant restraint with rigid LATCH attachments will not have any
flexibility that will allow it to be tipped backwards while remaining
connected to the lower anchorage bars. To solve this problem, Ford
suggested using the ECE Regulation 44 seat assembly, which has a
15 deg. bottom seat cushion angle, modified to have the LATCH anchorage
bars included in the assembly.\4\
---------------------------------------------------------------------------
\4\ The petition is granted to the extent it is consistent with
today's NPRM. However, granting of the petition does not mean that
the changes requested will be adopted. Granting of the petition
indicates that the agency believes that the recommended change has
merit and warrants further review and evaluation. A decision whether
to adopt the recommended change will be made on the basis of all
available information developed in the course of the rulemaking
proceeding, in accordance with statutory criteria.
---------------------------------------------------------------------------
ii. Seat Back Angle
Currently, the seat assembly has a seat back angle of 15 deg. off
vertical. Seventy-eight seat back angle measurements of rear seats in
the 35 vehicles surveyed were taken from either the outboard or center
seat position, or, if available, the third seating position. From this
analysis, the average seat back angle for all measurements taken is
22 deg. off of vertical. This is an increase of 7 deg. over the current
angle specified for the FMVSS No. 213 seat assembly. Forty-four percent
of all the measurements taken yielded seat back angles between 21 deg.
and 25 deg.. For these reasons, NHTSA proposes increasing the angle to
22 deg..
iii. Seat Belt Anchors
The current seat assembly has a lateral spacing of 222 mm between
the lap belt anchors in the center seating position, and a lateral
spacing of 500 mm for the outboard seating positions. Based on the
evaluation of the 35 vehicles surveyed, the average lap belt anchor
spacing in center seating positions in the modern vehicle fleet is 392
mm. Thirty-nine percent of the measurements taken for the center
seating position fell in the range of 351 mm to 400 mm, while 63
percent of the measurements were between 301 mm and 400 mm. As such,
the current seat assembly represents a distance that is 170 mm smaller
than that of the current vehicle fleet. We propose increasing the
spacing to 392 mm for the center seating position to represent the
average of the current vehicle fleet. Based on the evaluation of the 35
vehicles surveyed, the average lap belt anchor spacing in the outboard
seating positions is 472 mm, as compared to 500 mm on the current
Standard No. 213 standard seat assembly. Thirty-three percent of the
measurements taken were greater than 500 mm, while 90 percent were
above 400 mm. As the average anchorage spacing for outboard seating
positions in the modern vehicle fleet is 28 mm less than that on the
current standard seat assembly, we propose to change the spacing to 472
mm to more accurately represent actual vehicles. Comments are requested
on how changing the spacing will affect the performance of a child
restraint in dynamic tests.
iv. Fixed Seat Back
NHTSA proposes that the seat back of the seat assembly be changed
to represent a fixed vehicle seat. Steel rods should replace the
existing aluminum rods. A fixed seat back will be more representative
of the rear seat of today's passenger cars, and would harmonize with
ECE regulations. Because NHTSA strongly recommends that children under
the age of twelve ride in the back seat, changing the seat assembly to
represent a typical rear seat seems appropriate. However, vans and
multipurpose vehicles with multiple seating rows may be more closely
represented by a flexible seat back. Comments are requested on this
issue. NHTSA is currently evaluating the effect of the change on child
restraint performance by use of MADYMO simulations, and will further
study the effect of flexible versus rigid seat backs through sled
testing to be performed later this year.
4. Features That Need Not Be Changed
NHTSA has tentatively decided that the following features of the
bench seat need not be changed because they either reflect the design
of production seats or are different but that difference is deemed not
to have an effect on child restraint performance in dynamic testing.
Comments are requested on these features.
i. Bottom Seat Cushion Length
Currently, the seat assembly has a bottom seat cushion length of
508 mm. In order to find the average bottom seat cushion length, 78
measurements were taken in the 35 vehicles surveyed. Analysis depicts
the average seat pan length as 461 mm. The average bottom seat cushion
length for 64% of the measurements was found to lie within the range of
451 mm to 500 mm. Therefore, the current FMVSS No. 213 seat assembly
has a seat pan length that is about 50 mm longer than the average seat
pan length observed in today's vehicle fleet. We do not believe that
this difference is consequential, as the reduced seat cushion length
does not cause an incompatibility with existing child restraint
designs.
ii. Seat Back Height
Currently, the 213 seat assembly has a seat back height of 610 mm.
In the 35 vehicles surveyed, 78 measurements of the height of the seat
back were made in both the outboard and center positions. These data
yield an average seat back height of 619 mm. The highest percentage of
seat back length measurements fell within the range of 601 mm to 700
mm. This percentage
[[Page 21812]]
represented 64% of the vehicle measurements. Because the Standard No.
213 seat assembly is only 9 mm lower than the average seat back height
observed in today's fleet, we do not see a need to propose to raise the
height of the seat back.
iii. Test Bench Floor
In response to the agency's draft Child Protection System Safety
Plan, Ford recommended that the standardized bench seat should have a
floor (see Docket 7938-20). Ford believed that the current test seat
assembly cannot evaluate a rear-facing child restraint that is equipped
with a support leg, as has been developed and is currently used in
other countries. We are declining to add a floor to the test assembly
at this time, since Standard No. 213 does not allow support legs in
compliance testing. Under Standard No. 213, rear-facing restraints are
only to be attached to the seat assembly via the lap belt or the
anchorages of the LATCH system. As such, the inclusion of a floor
structure on the Standard No. 213 standard seat assembly is not
necessary at this time.
5. What About Cushion Stiffness?
Comments are requested on whether the seat assembly's cushion
should be made stiffer. PAX found the average stiffness of the Standard
No. 213 seat assembly to be marginally softer than most, but not all
new vehicles on the road today. The force deflection curves generated
by PAX show that the current Standard No. 213 seat cushion is softer at
both the fore and aft outboard positions than almost all seat cushions
in vehicles of the modern fleet. As part of the work performed in 1988
to reexamine the Standard No. 213 procedures,\5\ the stiffness
characteristics of the Standard No. 213 seat cushion material were
compared with the characteristics of then current model vehicle seats.
Static force versus deflection tests were conducted on the Standard No.
213 seat cushion foams, and these curves were then compared with
similar curves that had been developed for ten vehicles which had been
measured in a separate project in 1987. The distribution of force
versus deflection curves found in that evaluation closely parallel
those found by PAX, in that most vehicle seats were stiffer than the
Standard No. 213 seat assembly, but there was at least one vehicle seat
that was softer. Sled tests were performed in 1988 to compare the dummy
response of the Standard No. 213 seat cushion, a representative cushion
that was softer, and a stiff cushion. The dummy response differences
were not sufficiently large or consistent to warrant specifying a
different cushion than the foam used in Standard No. 213. Thus, the
Standard No. 213 cushion was considered to be ``representative'' of the
rear seats of then current cars.
---------------------------------------------------------------------------
\5\ Hiltner, Edward C. and MacLaughlin, Thomas F., ``Child
Seating Test Procedure Development,'' NHTSA Final Report No. DOT HS
807 466, March 1989.
---------------------------------------------------------------------------
We are interested in increasing the stiffness of the cushion, but
are uncertain what, if any, differences will be seen in dynamic
testing. We request comments on what the stiffness should be. Comments
are also requested on what effect changing the test seat stiffness
would have on child restraint performance in dynamic testing.
b. Crash Pulse
This NPRM would slightly revise the Standard No. 213 pulse. We
propose to extend the pulse to approximately 90 milliseconds (msec),
and to widen the test corridor to make it easier for more test
facilities to reproduce it. The expanded corridor would not reduce the
stringency of the test, and would also make it easier to conduct
compliance tests at speeds closer to 30 mph. We found in studying
vehicle crash pulses that the Standard No. 213 pulse is more severe
than most other pulses, but is similar to crash pulses of large sport
utility vehicles and light trucks--passenger vehicles that are becoming
more and more popular for use as family vehicles--and very similar to
the crash pulse of small school buses.
1. The Current Crash Pulse
In Standard No. 213's dynamic sled test, a test dummy is secured in
a child restraint, which in turn is attached to a representative
vehicle bench seat (seat assembly). The assembly is then subjected to
acceleration to simulate a vehicle crash. The child restraint must
manage the force from the simulated crash so that the forces imparted
to the dummy are within tolerable limits. The force imposed on the
child restraint and dummy is a function of the acceleration onset rate,
peak, and duration. Paragraph S6.1.1(b)(1) of Standard No. 213
specifies that when child restraints are tested in the 48 km/h (30 mph)
dynamic test, the acceleration of the test platform must be entirely
within the curve shown in Figure 2 of the standard.\6\ ``Crash pulse''
refers to the change in the sled's velocity over time. The severity of
a crash pulse is a function of its onset rate, peak g and its time of
occurrence, and duration. The standard has a relatively severe crash
pulse, in that the sled is accelerated relatively quickly to an
acceleration of approximately 24 g's (24 times the force of gravity)
and maintains the 24 g level for a relatively long time period (37 to
42 msec) before returning to zero acceleration.
---------------------------------------------------------------------------
\6\ Our laboratory test procedure (TP) for Standard 213 (TP-213-
04, September 1, 1997), specifies a ``tolerance band,'' or
``acceleration function envelope,'' that incorporates the upper
limit of Figure 2 and that also sets a lower limit (see section
D.3.3, ``Impact Severity'' (page 53)).
---------------------------------------------------------------------------
Pulses can vary as to their shape, onset rate, peak acceleration,
and duration. NHTSA's research in the mid-1990's showed that Standard
No. 213's pulse was more severe than the ``average car'' pulse of 1988-
1991. Crash pulses obtained from Standard No. 208 vehicle crash tests
indicated a peak G occurring much later in the crash event compared to
Standard No. 213 and a longer pulse duration. The upper limit of the
Standard No. 208 pulse ended at 135 msec, compared to 81 msec for the
Standard No. 213 pulse.
Since the mid-1970's, vehicle front ends of passenger cars have
become softer, allowing for more front-end crush to take place. This
results in crash pulses that are much longer in duration than car crash
pulses of 30 years ago. Current cars have crash pulses that are
generally longer in duration than that of Standard No. 213. The peak
G's are similar, so the longer duration means that the average model
year 2001 passenger car has a less severe pulse than the standard.\7\
Because of these changes in car design, we have been asked to
reconsider the crash pulse in Standard No. 213 to ensure that it is
representative of the crash pulses of today's vehicles. See, e.g.,
Ford's comment on NHTSA's draft Child Restraint Systems Safety Plan,
docket 7938-20.
---------------------------------------------------------------------------
\7\ FMVSS No. 213's pulse is quite different than any other
pulse used to regulate child restraints. The Europeans, the
Canadians and the Australians all use different crash pulses to test
their child restraints. The FMVSS No. 213 pulse seems to be more
severe than the other pulses because of its sharp rise time and the
short duration of the crash pulse. Of these three international
pulses, the only similarity between the three was the time duration.
All other pulses used to regulate child restraints, except FMVSS No.
213, ended beyond 100 msec. The U.S. has about 10 times the LTV
sales as Europe (50 percent versus 5 percent). In Australia, LTV
sales constitute about 25 percent of the total vehicles sold in that
country.
---------------------------------------------------------------------------
We have also been asked to re-examine the crash pulse because it is
difficult to duplicate due to the narrow corridors in the laboratory
test procedure. Very few labs are able to replicate the 213 pulse.
Transportation Research Center (TRC), a testing laboratory, submitted a
petition to NHTSA on October 6, 1999, which we
[[Page 21813]]
granted, regarding the pulse corridor specified in the laboratory test
procedure for Standard No. 213. Due to features of the TRC sled and
others of its type generally (HYGE), TRC stated that there is a problem
with achieving the acceleration curve specified in the standard and
suggested that the pulse can be slightly revised, by manipulating time
zero, to accommodate HYGE sleds without affecting test results.
Standard No. 213 specifies that, when testing child restraints in
the 48 km/h test, the acceleration of the test platform must be
entirely within a specified curve. The curve begins at zero g's and
zero time. TRC stated that its HYGE sled is generally unable to produce
the required acceleration curve. The sled ``fires'' by cracking a seal
between a high pressure chamber and a low pressure chamber, with the
flow of gas (around a metering pin, which controls acceleration curve
shapes) from high pressure to low pressure providing the acceleration
force. TRC explained that initially, the area available for gas flow is
small, and a short amount of time is required for pressure to build
enough to cause significant acceleration. Because there is a lag time
between initiation of the test and appreciable acceleration of the
sled, when the curve begins at zero g's and zero time, a significant
portion of the curve is not within the tolerance band required by the
present test procedure. When time zero is manipulated so that the
initial acceleration pulse falls within the zero to 10 millisecond
envelope, and the acceleration at time zero is 1.25 g's, the required
tolerance band is achieved.
We have determined that TRC's petition merits consideration. In
December 1998, NHTSA issued a final rule amending the sled test
requirement in Standard 208, ``Occupant Crash Protection,'' by, among
other things, revising how time zero is defined (63 FR 71390, December
28, 1998). The sled test in that standard tests occupant response for
air bag restraint systems. In that rulemaking, NHTSA determined that it
is impractical for that test to have time zero at 0.0 g acceleration,
because of the time lag between initial movement of the sled and
significant acceleration. The agency decided that the start of the sled
test will be determined by a specific acceleration level for the sled
which corresponds to a time at which the most rapid acceleration
begins, at about 0.5 g's (63 FR at 71393). Similarly, TRC would like
NHTSA to revise its pulse envelope specifications for child restraint
testing to allow a small deviance at time zero ``so that * * * sleds
[similar to TRC's] may defendably participate in certification and
compliance testing.''
2. The Crash Pulse Is Not Overly Severe
Following passage of the TREAD Act, NHTSA had PAX analyze the crash
pulses of over 150 vehicles tested under FMVSS No. 208 and under the
agency's frontal New Car Assessment Program (NCAP). Based on the
analysis of model year (MY) 1995 to MY 2000 vehicles, PAX found that
the current pulse in Standard No. 213 was more severe \8\ than that of
most passenger vehicles in today's fleet, but was similar to the pulses
of truck and truck-like multipurpose passenger vehicles (i.e., large
sport utility vehicles, SUVs) in Standard No. 208 tests, except that
the truck pulse was much longer in duration than the Standard No. 213
pulse. A report by PAX on the research project is available in the
docket.
---------------------------------------------------------------------------
\8\ A more severe crash pulse is defined as one having a higher
acceleration onset rate, higher peak acceleration, and/or a shorter
time duration.
---------------------------------------------------------------------------
To summarize the report, PAX obtained ``average'' crash pulses from
the FMVSS No. 208 vehicle crash tests and NCAP tests. To obtain average
NCAP and FMVSS No. 208 pulses, 59 vehicles were separated into 4
classes: Cars, SUV's, trucks, and vans. The pulses were then filtered,
and the peak velocity, peak G, and duration of the crash pulse were
recorded.
The Society of Automotive Engineers (SAE) Recommended Practice for
electronic processing of vehicle crash test acceleration data, as given
in SAE J211, is Channel Frequency Class 60. Filtered at SAE J211 Class
60 (100 Hz cutoff frequency), the average car pulse had a peak
acceleration of 24 g's at 70 msec and pulse duration of approximately
115 msec. When this pulse was overlaid with the Standard No. 213 pulse,
the 213 pulse enclosed no portion of the average car curve. The average
car had an initial slope similar to FMVSS No. 213, but then the vehicle
began to crush before stiffening up again. For vans, the average van
pulse had a peak acceleration of 22 g's at 42 msec and pulse duration
of 140 msec. Both the van pulse and the 213 pulse had almost identical
rise times, but then after 10 msec, the van pulse began to behave like
the car pulse. However, small portions of the van pulse were enclosed
by the 213 pulse corridor.
With SUV's, the average SUV pulse had a peak acceleration of 26 g's
at 27 msec and a pulse duration of 113 msec. When the SUV pulse was
overlaid with the 213 corridor, the time of peak G for the SUV pulse
was very similar to the 213 pulse, which peaks at 20 msec, and the rise
time between the two pulses was also very similar. Portions of the SUV
pulse fell within the 213 corridor a number of times.
For pick-up trucks, the average truck pulse had a peak acceleration
of 26 g's at 24 msec and a pulse duration of 114 msec. When the truck
pulse was overlaid with the 213 corridor, there were many similarities.
Not only did the two curves peak at almost the same time but the rise
time was very similar. Also, for the first 65 msec, the truck pulse
fell within the corridors of 213 many times. Although the duration of
the pulse was different, the truck pulse and the 213 pulse appeared to
be very similar.
A summary of the PAX findings are set forth in Table 4.
Table 4.--Summary of PAX Pulse Data Filtered at SAE Class 60 (100 Hz)
----------------------------------------------------------------------------------------------------------------
Time (msec)
Pulse type Peak G ------------------------ V
Duration Peak G (kph)
----------------------------------------------------------------------------------------------------------------
Average Passenger Car........................................... 24 115 31 55
Average SUV..................................................... 26 113 35 52
Average Truck................................................... 29 114 39 52
Average Van..................................................... 22 140 26 54
FMVSS No. 213................................................... 21 81 20 48
----------------------------------------------------------------------------------------------------------------
[[Page 21814]]
Based on this information, we have decided not to reduce the
severity of Standard No. 213's crash pulse. PAX found that the current
crash pulse is very similar to the pulse of light trucks, SUVs and
small school buses in acceleration onset rate and peak magnitude.
Figures 2, 3 and 4 plot acceleration curves of SUVs, trucks, and a
small school bus. These plots show that the existing Standard No. 213
pulse corridor closely represents pulses of these vehicles. As shown in
the figures, the first 70 msec represents several modern day vehicles
used to transport children. Increasingly, light trucks, SUVs and small
school buses are being used to transport children in child restraints.
Based on these findings, we conclude that the stringency of the FMVSS
No. 213 crash pulse is justified to better ensure that each child
restraint will not have structural degradation in a crash, and will
limit forces to the head, neck, and torso to tolerable levels, no
matter the vehicle the child is in.
The agency is seeking comment on whether a more severe crash pulse
should be established for testing child restraint systems. Comments are
sought on the trapezoidal-shaped corridor proposed, and on the
parameters that determine the level of severity of a pulse for child
restraint systems. Does the trapezoidal-shaped corridor provide a
sufficient representation of the current vehicle fleet, or are there
other pulse shapes that would be more representative and/or more
severe?
The agency is also seeking comment as to whether the total change
of velocity of the current Standard No. 213 pulse (delta v = 30 mph)
should be increased to 33 mph to be equivalent to a 30 mph crash into a
rigid barrier. Typically, a delta v of 33 mph is seen in a 30 mph rigid
wall test required for adult protection in Standard No. 208.
3. Adjusting the Corridors of the Pulse
We are proposing minor revisions to the crash pulse. We would
extend it to approximately 90 msec, and would widen the test corridor
so that several testing facilities can satisfactorily reproduce the
FMVSS No. 213 crash pulse (see figure 5). The expanded corridor would
not sacrifice the stringency of the current pulse. The proposal would
ensure the rapid rise as is currently in the standard but also
accommodate small deviations at time zero as requested by the TRC
petition. The change in the boundary of the corridor would provide
laboratories the flexibility to generate a pulse that would be closer
to a V = 30 mph.
BILLING CODE 4910-59-P
[[Page 21815]]
[GRAPHIC] [TIFF OMITTED] TP01MY02.001
[[Page 21816]]
[GRAPHIC] [TIFF OMITTED] TP01MY02.002
[[Page 21817]]
[GRAPHIC] [TIFF OMITTED] TP01MY02.003
[[Page 21818]]
[GRAPHIC] [TIFF OMITTED] TP01MY02.004
BILLING CODE 4910-59-C
NHTSA proposes that the sled pulse for Standard No. 213 (see figure
5, above) should have the coordinates given in the following table 5:
Table 5.--Proposed Sled Pulse Coordinates
------------------------------------------------------------------------
Point Time Acceleration
------------------------------------------------------------------------
Upper Bound
------------------------------------------------------------------------
A................................................ 0 3
B................................................ 10 25
C................................................ 52 25
D................................................ 90 0
------------------------------------------------------------------------
Lower Bound
------------------------------------------------------------------------
E................................................ 4 0
F................................................ 13 19
G................................................ 46 19
H................................................ 75 0
------------------------------------------------------------------------
NHTSA will be further evaluating the proposed changes. Sled tests
using the proposed crash pulse will be conducted later this year, and
the information we obtain will be placed in the docket. Results of this
testing will be compared to compliance test data of existing child
restraints to evaluate the effect of the changes. Comparison of these
tests will aid in the agency's decision as to whether the proposed
changes should be adopted in a final rule.
c. Improved Child Test Dummies
This document proposes two initiatives toward enhancing the use of
test dummies in the evaluation of child restraints under Standard No.
213. NHTSA proposes to replace some of the existing dummies with
improved dummies representing children of approximately the same age as
the replaced dummies. NHTSA also proposes testing child restraints for
older children by using a weighted 6-year-old dummy (i.e., a dummy to
which weights have been added). The total weight of the dummy would be
62 lb. The weighted dummy would be used to test child restraints that
are recommended for children weighing 50 to 65 lb. (This NPRM also
proposes expanding the applicability of Standard No. 213 to restraint
systems recommended for use by children weighing up to 65 lb. See
section IV(e) of this preamble.)
Child restraint systems must be certified as meeting Standard No.
213's requirements when dynamically tested with test dummies that
represent children of different ages. The current dummies used in
Standard No. 213 compliance testing are the uninstrumented newborn
infant, the uninstrumented 9-month-old infant, and the Hybrid II 3- and
6-year-old dummies. NHTSA selects which test dummy to use based on the
mass of the children for whom the manufacturer recommends for the child
restraint. Table 6 sets forth which dummies are used to test child
restraints based on the mass recommendations established for the
restraint by the manufacturer. If a child restraint were recommended
for a range of children whose mass overlaps, in whole or in part, two
or more of the mass ranges in the table, the restraint is tested with
the dummies specified for each of those ranges. Thus, for example, if a
child restraint were recommended for children having masses greater
than 13 kg and up to 20kg, it would be tested with the 9-month-old
dummy, the 3-year-old dummy and the 6-year-old dummy.
Table 6.--Use of Current Dummies
------------------------------------------------------------------------
Dummy(ies) currently used in
Recommended mass range (kilograms) compliance testing
------------------------------------------------------------------------
Not greater than 5 kg (0 to 11 lb). Newborn.
Greater than 5 but not greater than Newborn, 9-month-old.
10 kg (11 to 22 lb).
Greater than 10 but not greater 9-month-old, Hybrid II 3- year-old.
than 18 kg (22 to 40 lb).
Greater than 18 (40 to 50 lb)...... Hybrid II 6- year-old.
------------------------------------------------------------------------
[[Page 21819]]
1. CRABI, Hybrid III Dummies
i. Replacing Current Dummies
The first initiative is a proposal to replace three of the test
dummies now used in Standard No. 213 compliance tests with new test
dummies. The design and performance criteria for the new dummies were
incorporated into NHTSA's regulation for anthropomorphic test devices,
49 CFR part 572, by rulemaking actions concluded last year. The new
dummies are the Child Restraint Air Bag Interaction (CRABI) 12-month-
old infant dummy (Part 572, Subpart R), the Hybrid III 3-year-old child
dummy (Subpart P), and the Hybrid III 6-year-old child dummy (Subpart
N). The dummies are used in compliance tests that the agency adopted
last year for testing advanced air bag systems under Standard No. 208,
``Occupant Crash Protection.'' We would retain the newborn infant dummy
in Standard No. 213's compliance tests, but would replace the 9-month-
old dummy (Part 572, Subpart J) with the CRABI.\9\ We would replace the
Hybrid II 3- and 6-year-old dummies with their Hybrid III (HIII)
counterparts. Thus, just as in the protocol today under Standard No.
213, there would be four child test dummies used for compliance
testing.
---------------------------------------------------------------------------
\9\ Britax Child Safety Inc. submitted a petition for rulemaking
on September 22, 2000, to allow manufacturers to specify use of the
CRABI in compliance testing in place of the 9-month-old dummy. To
the extent the petition is consistent with this NPRM, it is granted.
---------------------------------------------------------------------------
The new dummies were incorporated into Part 572 because they
comprise a new generation of test dummies that are more representative
of human children than their Hybrid II counterparts, and allow for the
assessment of the potential for more types of injuries in motor vehicle
crashes. The biofidelity, reliability and repeatability of the test
dummies were discussed in the final rules incorporating the dummies
into Part 572. See, final rules for the CRABI (65 FR 17188; March 31,
2000); Hybrid III 3-year-old (65 FR 15254; March 22, 2000); Hybrid III
6-year-old dummy (65 FR 2065; January 13, 2000). The CRABI dummy is
instrumented with head, neck and chest accelerometers, while the 9-
month-old dummy is not. The Hybrid III child dummies have a broader
selection of instruments to assess the injury potential to child
occupants, including a multi-segmented neck, multi-rib thorax and
abdominal load monitors, while the Hybrid II dummies have limited
biofidelity in the neck area and are not instrumented to measure neck
injury. Because of their superior instrumentation, the CRABI dummy and
the Hybrid III child dummies can provide a fuller evaluation of the
performance of child restraint systems in protecting young children.
Simply substituting the dummies for the existing ones might not, in
itself, affect child restraint performance. There does not seem to be a
significant difference between the Hybrid II and Hybrid III dummies in
their ability to measure head and chest accelerations or in dummy
kinematics relevant to head and knee excursions. A series of frontal,
Standard No. 213 sled tests were conducted to evaluate the equivalency
between the Hybrid II child dummies currently used in the standard with
the CRABI dummy and the Hybrid III 3- and 6-year-old dummies. Results
from previously performed compliance tests (Hybrid II dummies) were
identified, and the Hybrid III and CRABI dummies were seated in various
CRS and vehicle belt configurations in order to establish a full
complement of tests with both the Hybrid II and Hybrid III dummies.
Where needed, additional sled tests were performed with the Hybrid II
dummies. HIC, chest acceleration, and head and knee excursion values
were compared between the Hybrid II and Hybrid III dummies for each age
group. Test results indicate similar performance between the Hybrid II
and Hybrid III child dummy families. See, ``A Comparative Evaluation of
the Hybrid II and Hybrid III Child Dummy Families,'' a copy of which
has been placed in the docket. Nonetheless, replacing the Hybrid II 3-
and 6-year-old dummies with their Hybrid III counterparts would enhance
safety by the latter's greater instrumentation capabilities and
improved biofidelity, and by the adoption of injury criteria that the
Hybrid II dummies cannot measure. This NPRM proposes new injury
criteria of that sort, which are discussed in section V (f), infra.
ii. Retaining the Criteria Used To Determine Which Dummy Is Used in
Compliance Tests
NHTSA proposes to retain the criteria that are used to determine
which dummy is used in Standard No. 213's compliance test. Table 7 sets
forth the dummies that would be used to test child restraints, based on
the mass of the children for whom the restraint is recommended.
Table 7.--Proposed Use of New Dummies
------------------------------------------------------------------------
Dummy(ies) currently
Recommended mass range used in compliance Dummies proposed for
(kilograms) testing use
------------------------------------------------------------------------
Not greater than 5 kg (0 to Newborn............. Newborn.
11 lb).
Greater than 5 but not Newborn, 9-month-old Newborn, CRABI.
greater than 10 kg (11 to
22 lb).
Greater than 10 but not 9-month-old, 3-year- CRABI, HIII 3-year-
greater than 18 kg (22 to old. old.
40 lb).
Greater than 18 kg but not 6-year-old.......... HIII 6-year-old.
greater than 22.7 kg (40 to
50 lb).
Greater than 22.7 kg (Over .................... Weighted HIII 6-year-
50 lb). old.
------------------------------------------------------------------------
Comments are requested on the merits of replacing the existing
dummies with the three new ones. The agency has tentatively decided
that it would no longer use the 9-month-old dummy (which weighs 20 lb)
to test child restraints because the newborn and the CRABI (22 lb)
appear sufficient to evaluate the performance of a child restraint
recommended for infants. Comments are requested on whether the 9-month-
old dummy would still be needed to test child restraints, and if so,
which restraints should be tested with that dummy. The 9-month-old
dummy better represents a 9-month-old child than the CRABI, since the
CRABI is slightly more massive as a device representing a 12-month-old.
Thus, retaining the 9-month-old in compliance testing might increase
the scrutiny of the standard of infant restraints, which argues for
continued use of the dummy in compliance tests (although there would be
costs associated with such use). Also, some rear-facing infant car
seats/carriers that are designed with a
[[Page 21820]]
handle for toting the infant outside of the vehicle are recommended for
use with infants weighing only up to 20 lb. Even though the CRABI (at
22 lb) is heavier than the children recommended for those restraints,
we tentatively conclude that the CRABI can and should be used in
compliance tests of these restraints because it is instrumented and the
9-month-old (20 lb) dummy is not. Do all infant car seat/carriers have
back supports that are high enough to support the CRABI?
Relatedly, the agency's policy has been, to the extent possible, to
test each child restraint with dummies that are at the ends of the
weight range of children for whom the restraint is recommended. The
smaller of the two dummies with which we test child restraints is used
for assessing the potential for ejection, while the larger dummy is
used for assessing structural integrity. Be that as it may, we would
test a child restraint that is recommended for use by children weighing
20 to 40 lb forward-facing with the CRABI (22 lb) dummy, and not with
the 9-month-old (20 lb) dummy, even though the 9-month-old dummy is
closer in weight/mass to the lower end of the recommended weight range
for the restraint. The difference in stature between the 9-month-old
and the 12-month-old CRABI is nominal--the 9-month-old is 27.9 inches
tall, while the 12-month-old CRABI is 29.4 inches tall (the sitting
heights are 17.7 inches and 18.3 inches, respectively). As such, both
dummies will likely provide nearly identical measures of the
possibility for ejection. Comments are requested on this issue.
Comments are requested on whether there is a need to specify in
Part 572 a test dummy representing an 18-month-old child. Transport
Canada has evaluated an 18-month-old CRABI child dummy that weighs 25
lb. However, because NHTSA has not evaluated the dummy, we have not
assessed whether it should be used in compliance testing. There also
does not appear to be a significant need for the dummy. The dummy would
be used in tests of convertible\10\ restraints that are recommended for
use in the rear-facing configuration by children weighing over 22 lb.
As noted above, restraints that are recommended for use by children
over 22 lb (and less than 40 lb) are subject to testing with the Hybrid
II 3-year-old (33 lb) dummy. Virtually all convertible restraints
currently on the market are certified rear-facing for up to at least 30
lb, and often to 35 or 40 lb. The 3-year-old dummy therefore is more
representative of children at the upper end of the recommended weight
ranges for these restraints than the 18-month-old dummy.
---------------------------------------------------------------------------
\10\ A convertible child restraint can be used rear-facing with
infants and young toddlers, and forward-facing with older toddlers.
They typically are recommended for use by children from birth until
the child reaches 40 lb.
---------------------------------------------------------------------------
The height recommendations would not change. The 850 mm height
criterion was originally based on the 95th percentile 1-year-old and
not the 9-month-old, so the substitution of the CRABI 12-month-old for
the 9-month does not require a change.
Table 8.--Dummy Selection Based on Height Recommendations
------------------------------------------------------------------------
Dummy(ies) currently
Recommended height range used in compliance Dummies proposed for
(kilograms) testing use
------------------------------------------------------------------------
Not greater than 650 mm..... Newborn............. Newborn.
Greater than 650 mm but not Newborn, 9-month-old Newborn, CRABI.
greater than 850 mm.
Greater than 850 mm but not 9-month-old, HII 3- CRABI, HIII 3-year-
greater than 1100 mm. year-old. old.
Greater than 1100 mm........ HII 6-year-old...... HIII 6-year-old.
------------------------------------------------------------------------
iii. Conditioning the Dummies
This document proposes detailed descriptions of the clothing,
conditioning and positioning procedures for the dummies to ensure that
the test conditions are carefully controlled.
Clothing for the 12-month-old CRABI and the Hybrid III 3- and 6-
year-old dummies is currently specified in the corresponding sections
of Part 572 that identify the design and performance criteria for each
dummy. (Clothing is described in Sec. 572.154(c)(2) of Part 572 for the
CRABI 12-month-old; in Sec. 572.144(c)(1) for the Hybrid III 3-year-
old; and in Sec. 572.124(c)(2) for the Hybrid III 6-year-old.) It is
proposed that the clothing specified in Part 572 for each dummy be used
in the Standard No. 213 compliance test, except with respect to the
identification of appropriate footwear. S9.1(c) of Standard No. 213
prescribes size 7M sneakers for the 3-year-old dummy and size 12\1/2\ M
sneakers for the 6-year-old dummy with rubber toe caps, uppers of
Dacron and cotton or nylon and a total mass of 0.453 kg. No such
specifications are in Part 572. As such, we propose that S9.1(c)
Standard No. 213 maintain the specification of footwear for the Hybrid
III 3- and 6-year-old dummies. The clothing and footwear for the
weighted 6-year-old dummy (see section V.d.2, infra) would be the same
as that specified in Part 572 for the Hybrid III 6-year-old dummy.
The conditioning specifications specified in S9.3 of Standard No.
213 would be revised to reflect the same pre-test conditioning
procedures that are currently specified in Standard No. 208 for the
CRABI 12-month-old and the Hybrid III 3- and 6-year-old dummies.
Namely, each dummy would be maintained at a temperature between 69 and
72 degrees F (between 20.6 and 22.2 degrees C) for at least 4 hours
prior to a test. This would ensure that each dummy is conditioned in a
manner that is consistent with the provisions specified in Part 572 for
each dummy and its specific subassemblies. The dummy positioning
requirements in S10 of Standard No. 213 would remain essentially
unchanged. We note that S10.2.1(a) of Standard No. 213, which specifies
rotating the legs of the 9-month-old dummy prior to placement of the
dummy in a child restraint, is not needed for the CRABI 12-month-old
dummy because of the spinal structure of the CRABI dummy.\11\
---------------------------------------------------------------------------
\11\ The proposed regulatory text of this NPRM retains the
specifications in Standard No. 213 for conditioning and positioning
the 9-month-old dummy and the Hybrid II dummies because the dummies
would continue to be used in compliance tests until the mandatory
compliance date of a final rule (which is proposed to be November 1,
2004).
---------------------------------------------------------------------------
2. Using a Weighted 6-Year-Old Dummy
The second initiative relates to enhancing the dynamic evaluation
of child restraints that are designed for older children. This NPRM
proposes to use a weighted Hybrid III 6-year-old dummy to test child
restraints that are
[[Page 21821]]
recommended for use by children with masses up to 29.5 kg (65 lb).
A child reaching 40 lb (18 kg) has outgrown a convertible or
toddler restraint, but still must be restrained by special means to
safely ride in a vehicle. Parents tend to move these young children
into the vehicle belt system, only to find that the lap and shoulder
belts do not properly fit their children. The children are not yet
large enough to sit with their backs against the vehicle seat back
cushion with their knees bent over the seat edge. To compensate for a
shoulder belt crossing their face or neck, some children tend to place
the shoulder belt behind their backs, which results in no restraint of
the child's upper torso. Children also find it more comfortable to bend
their knees at the vehicle seat cushion's edge than to ride with the
edge of the cushion pressing against their calves. Because their legs
are not long enough to enable them to bend their knees at the cushion's
edge while riding in a vehicle, children generally slouch down in the
vehicle seat and scoot forward on the seat. Slouching raises the lap
belt over their soft-tissue areas, which exposes abdominal organs to
crash forces that can be imposed by the lap belt.
Klinich et al. estimates that children who are less than 148
centimeters in standing height do not adequately fit the seat belt and
seating system in vehicles (``Study of Older Child Restraint/Booster
Seat Fit and NASS Injury Analysis,'' DOT HS 808 248, November 1994.)
Current NHTSA guidelines recommend booster seat use for children up to
age 8, unless the child is 4' 9".
A booster seat improves the fit of a vehicle's belts on children.
Booster seats are ``child restraint systems'' regulated in the same
manner as other child restraint systems by Standard No. 213. The
boosters come in a variety of styles, the majority having high-backs,
with shoulder strap adjuster features on the sides. Belt-positioning
seats (also referred to as ``belt-positioning boosters'') must be used
with a lap and shoulder belt system. Boosters provide a raised seating
platform for the child, which provides a taller sitting height. Raising
the child helps position both the vehicle's lap and shoulder belts
correctly. The seating platform also allows the child's knees to bend
comfortably while the child is riding in the vehicle, which greatly
reduces the tendency to slouch. Booster seats are dynamically tested by
the agency using the 6-year-old test dummy, which weighs approximately
48 pounds and is about 48" tall.
In September 1996, the NTSB issued Safety Recommendation H-96-25,
which asked NHTSA to revise Standard No. 213 to establish performance
standards for booster seats that can restrain children up to 80 pounds.
The Safety Board expressed concern about the performance of boosters
when restraining a child that weighs more than the 6-year-old dummy
that is currently used in Standard No. 213 compliance testing. This
concern was also expressed by the Blue Ribbon Panel II in March 1999
(``Blue Ribbon Panel II: Protecting Our Older Child Passengers'') in
its report on ways to increase the use of age- and size-appropriate
occupant restraints by children ages 4 through 15. Most booster seats
currently on the market are certified for use by children weighing up
to 80 lb. To better evaluate the performance of these boosters with
children at the higher end of the weight range recommended for the
restraint, the agency is pursuing two separate but parallel efforts to
address the protection needs of older children. The first is a long-
term program to develop a 76-lb, 10-year-old dummy. The second is a
short-term initiative to use a weighted 6-year-old dummy to test
booster seats beyond the 50-lb weight limit specified in FMVSS No. 213.
The weighted dummy weighs 62 lb.
i. Development of the 10-Year-Old Dummy Is a Long-Term Measure
A 10-year-old dummy is being developed, but it is not far enough
along in its development to be part of this NPRM.\12\ The following
summarizes the work on the dummy thus far.
---------------------------------------------------------------------------
\12\ The legislative history to TREAD indicates that Congress
was interested in the potential for using the 10-year-old dummy
specified in ECE 44. That dummy is manufactured by the Netherlands
Organisation for Applied Scientific Research (TNO), which
manufactures the other test dummies referenced in ECE 44. These
dummies are TNO's ``P'' series of child dummies, which includes a
newborn, a 9-month, 18-month, and 3-, 6-, and 10-year-old. All P
series dummies are of similar construction. The agency evaluated the
3-year-old child dummy and found it to have insurmountable seating
stability problems when placed in a child restraint, and un-human-
like impact kinematics because of its cervical and thoracic spine
construction. We also found problems with the instrumentation. As a
result, because of design similarities of all P series dummies, our
engineering judgment was the 10-year-old TNO dummy would not be
suitable for use in crash testing. Subsequently, TNO began
developing the Q series dummies, which appear likely to be more
biofidelic, stable and reliable than their predecessor. The dummies
are still in development and are not available for use now.
---------------------------------------------------------------------------
In early 2000, NHTSA asked the Society of Automotive Engineers
(SAE) Dummy Family Task Group (DFTG) to develop a test dummy
representative of a 10-year-old child. The development and adoption of
a dummy this size is seen as a long-term solution to ensuring the
proper restraint of the approximately 10 percent of the population
between the sizes of 6-year-olds and 5th percentile adult females, and
could potentially be used in evaluating the performance of booster
seats and vehicle belt systems. The group met initially in May 2000 to
define the concept. The weight and height of the proposed dummy were
provided from the Center for Disease Control Data Bank, and was
targeted to be approximately 4'6" and 72 lb. The basic construction was
envisioned to be similar to that of the small female dummy. The dummy
was to be able to be positioned in erect seated, slouched seated,
standing, and kneeling postures to fully evaluate possible restraint
configurations.
The task group held its first review meeting in June 2000, and
reviewed impact responses scaled from the small female and 6-year-old
dummies. At that time, provisional performance requirements were
defined, and the anthropometry and mass goals were finalized. The dummy
instrumentation was specified to measure injury parameters for the
following body regions: head, neck, shoulder, thorax, pelvis, femur,
and tibia.
The first 10-year-old prototype was assembled in February 2001. It
weighed about 76 lb. The task group reviewed this prototype, and
directed design corrections. Subsequently, the first drawings were
completed in April 2001. GM and NHTSA separately performed preliminary
dummy performance verifications in Spring 2001 and Summer 2001,
respectively. The agency is now conducting an extensive evaluation of
the dummy, which will include a series of sled testing of the dummy. If
no problems are encountered, NHTSA may issue an NPRM proposing the
incorporation of the 10-year-old dummy into Part 572 by early 2003.
When it issues such an NPRM, NHTSA will also undertake rulemaking on
Standard No. 213 to propose using the dummy in compliance tests. At
this time, we invite views on the development and potential use of the
10-year-old dummy in Standard No. 213's compliance tests.
ii. A Weighted 6-Year-Old Dummy Is a Feasible Short-Term Alternative
As a short-term, interim measure, NHTSA is proposing the use of a
weighted Hybrid III 6-year-old dummy (hereinafter ``HIII-6CW'') for use
in testing child restraints that are recommended for use by children
weighing from 50 to 65 lb.
The agency developed the dummy by adding weights to the current
Hybrid III 6-year-old child dummy to increase the
[[Page 21822]]
total weight from approximately 52 pounds \13\ to over 60 pounds.\14\
NHTSA added approximately 10 pounds to the dummy so that it could be
used to represent slightly heavier children. The initial design concept
utilized carbon steel weights that were rigidly attached to the dummy
in two locations: (1) a weight located on the superior side of the
pelvis between the pelvis and the lumbar adaptor; and (2) weights
located on the lateral sides of the thoracic spine box. The steel
pelvis weight added 3.8 pounds to the dummy while the spine weights
added a total of 5 pounds (each weight was 2.5 pounds on right and left
sides). The resulting dummy weight was approximately 60 pounds. The
modifications also increased the dummy's seating height by one inch.
This change in stature appeared to be acceptable; a heavier occupant
could also be slightly taller.
---------------------------------------------------------------------------
\13\ The Hybrid III 6-year-old dummy weighs about 51.5 lb,
whereas the Hybrid II dummy weighs approximately 48 lb. A 50th
percentile 6-year-old weighs 51 lb.
\14\ The agency originally began this project by evaluating
whether weight could be added to the HIII 6-year-old dummy by way of
a weighted vest. We purchased a weighted vest from First Technology
Safety Systems, a dummy manufacturer, to evaluate its design. The
weights were contained in pouches located over the abdomen in the
front and over the lower back of the dummy's posterior. On
inspection of the vest on the dummy, we decided that this design
would be unacceptable for use in compliance testing. Because the
weights were not rigidly attached to the dummy, the weights could
rattle or even slap in a dynamic event and possibly create noisy
data signals in the dummy's instrumentation responses. Further, the
vest was somewhat bulky, and the agency was concerned that it could
affect the positioning of the dummy within the restraint system. The
agency therefore concluded that the weighted vest concept was not a
feasible alternative.
---------------------------------------------------------------------------
Following preliminary testing with the carbon steel weights and
upon experiencing some belt retention problems, we determined that
better weight and center of gravity distributions could be achieved
through the use of a dense Tungsten alloy material. The geometry of the
spine and pelvis weights was redesigned to achieve a weight of 5.1
pounds for the pelvis weight and 5.2 pounds total for the spine
weights. The increased density offered by the Tungsten alloy allowed
each of the weights to be reduced in size, thus reducing the
possibility of interference between the ribs and the spine weights.
Further, the dummy's seated height was only increased by approximately
0.7 inches over the unweighted HIII-6C dummy.
Preliminary evaluation tests have been conducted on dummies
equipped with both the steel and Tungsten alloy versions of the
weights. These tests included thoracic calibration impacts, torso
flexion tests, and dynamic sled tests. The weights withstood dynamic
impacts and testing without causing excessive noise or vibrations in
the data channels. (Adding the weights does not require any permanent
modifications to the dummy. When the weights are removed, the dummy
reverts to its original condition and meets the existing Part 572
specifications for the Hybrid III unweighted 6-year-old dummy.)
Component tests conducted with the steel version indicate that the
added weights did not appear to introduce structural or instrumentation
problems. The thoracic responses met the calibration requirements of
the unweighted HIII-6C dummy; however, the peak probe force measured
during the compression interval was near the upper end of the corridor.
Thus, the thoracic impact response corridor may need to be adjusted for
the weighted dummy. Electronic responses and visual observations
confirmed that there was no contact between the ribs and the spine
weights during the oblique impacts. The torso flexion tests also met
all of the requirements of the unweighted HIII-6C dummy.
Sled tests have been conducted with both the steel and Tungsten
versions. For all sled tests, the current Standard No. 213 pulse and
buck were used. Both versions of the dummy have been tested with
different booster seats and with 3-point (lap and shoulder) belt
systems. The results of the dummy, particularly with the high mass
Tungsten weights, appear to be reasonable as compared to the standard
HIII-6C dummy. That is, there have been no structural or electronic
deficiencies observed as a result of the sled testing. Additionally, a
series of four Standard No. 213 sled tests using various child
restraints were performed to compare the response of the unweighted
Hybrid III 6-year-old dummy to the HIII-6CW. Tests of the revised
weighted 6-year-old H-III dummy produced normal dummy kinematics
(motion in midsagittal plane) in booster seats and regular belt
systems.
A technical report discussing the agency's work in developing the
dummy, titled ``Evaluation of the Weighted Hybrid III Six-Year-Old
Dummy,'' has been placed in the docket. A proposal to incorporate the
specifications and performance criteria for the HIII-6CW in Part 572
will be published in early 2002 in the Federal Register.
d. Expanding the Applicability of the Standard to 65 Lb
NHTSA proposes to amend Standard No. 213 to increase the upper
limits of its applicability so that it would apply to child restraint
systems for children who weigh 65 lb or less. Currently, the standard
defines ``child restraint system'' as ``any device except Type I [lap]
or Type II [lap/shoulder] seat belts, designed for use in a motor
vehicle or aircraft to restrain, seat, or position children who weigh
50 pounds or less'' (S4). We would amend the definition to increase the
weight limit to 65 lb.
The effect of the amendment would be to apply Standard No. 213 to
devices that are recommended for children weighing 50 to 65 lb. There
has been considerable interest over the years in raising the limit to
require that child restraint systems that are recommended for older
children (i.e., booster seats) perform adequately in a crash. The aim
of raising the limit was to bring booster seats that are recommended
for children over 50 lb within Standard No. 213 and subject them to
that standard's dynamic test, just as other restraints are tested under
the standard. The intent to evaluate booster seat performance more
thoroughly by dynamically testing them could not be realized, however,
without a test dummy representing an older child. It would make little
sense to raise the standard's limit above 50 lb if a test device were
not available to test the performance of the restraint. Further,
booster seats were not being marketed so as to be beyond the standard's
purview; their recommended usage included children weighing less than
50 lb so they were, at least, subject to the 30 mph dynamic test with
the 6-year-old (48 lb) dummy. For these reasons, NHTSA decided against
increasing the 50 lb limit in the definition of ``child restraint
system.'' (See 58 FR 46928, 46932 for a discussion of the agency's
decision not to undertake rulemaking on this issue.)
Today, we are proposing to incorporate a weighted 6-year-old dummy
(62 lb total weight) into Part 572. We tentatively conclude that the
dummy can provide useful information on the performance of booster
seats that are recommended for children above 50 lb. Accordingly, we
propose to increase the 50 lb weight limit in the definition of child
restraint system to 65 lb. In the event that the weighted 6-year-old
dummy is not determined to be sufficient for testing child restraints
for children weighing above 50 lb, what would be the advantages and
disadvantages of raising the limit nonetheless? Regardless of whether
the
[[Page 21823]]
weighted 6-year-old dummy were adopted, comments are also requested on
the advantages and disadvantages of increasing the weight limit to
eighty pounds (80 lb) in the absence of an 80-lb test device. Our
tentative conclusion is that the weighted 6-year-old dummy is not
sufficient to assess the dynamic performance of a booster seat in
restraining an 80-lb child. Consumers Union (CU) has suggested in its
comment to the agency's draft child passenger protection plan (Docket
NHTSA-7938, page 11) that manufacturers should not be permitted to
recommend a child restraint for children of weights above the weight of
the largest test dummy used to evaluate the restraint in compliance
testing. NHTSA previously declined the suggestion, believing that
limiting the recommendations in the manner suggested could result in
safety losses. (For example, a manufacturer would not be able to
recommend a toddler restraint for children above the weight of the 3-
year-old dummy, 33 lb, which would result in 3-year-olds being
graduated out of child restraints at too early an age.) (61 FR 30824;
June 18, 1996.) Comments are requested on CU's suggestion with respect
to booster seats. If the weighted dummy were adopted, should
manufacturers be allowed to recommend boosters for children only up to
62 lb?
e. New or Revised Injury Criteria
This section describes proposed amendments to the measures that we
use to assess the performance of child restraints under Standard No.
213. We propose injury criteria that are the same as the scaled injury
criteria for children specified in Standard No. 208, Occupant Crash
Protection. We also propose some requirements similar to the static
testing requirements of Standard No. 213. The requirements that child
restraints must maintain system integrity and limit excursion of the
torso, head and knees in the simulated frontal impact would not be
changed.
The agency requests comments on each of the proposed injury
criteria. Comments are solicited on what risk levels are acceptable,
what factors should be considered in selecting performance limits and
whether the same limits as in Standard No. 208 should be established
for the child restraint standard. The two standards address different
sources of potential harm to children. The injury criteria for children
in Standard No. 208 are intended to minimize the risk from a deploying
air bag (ensuring that the air bag deploys in a manner much less likely
to cause serious or fatal injury to out-of-position occupants). The
injury criteria in Standard No. 213 are intended to limit the severity
of forces imposed on a child during a crash. Child restraints meeting
these criteria have worked effectively to maintain high levels of
performance in crashes. Because the injury criteria of the standards
are intended to minimize risks from different injury sources, it might
be reasonable to have non-identical criteria.
1. Scaled Injury Criteria
The injury criteria that a child restraint must meet when
restraining a dummy would change in several ways. Lower head and chest
injury criteria are proposed, but the duration within which
accelerations are measured would be limited. A new criterion for chest
deflection is also proposed, as well as new criteria for neck injury.
Currently, Standard No. 213 specifies a head injury criterion (HIC) of
1000 and maximum acceleration level for the chest (60g). These were
based on the criteria that were specified for the adult male test dummy
in Standard No. 208 in the early 1980's, when injury criteria were
incorporated into Standard No. 213 (44 FR 72131; December 13, 1979). At
that time, there were no injury criteria that were separately scaled
from an adult dummy to reflect anatomical differences and differing
injury tolerance of children. In the agency's May 2000 final rule on
advanced air bag technology, NHTSA amended Standard No. 208 by, among
other things, adjusting the criteria and performance limits to account
for motor vehicle injury risks faced by different size occupants. (65
FR 30680; May 12, 2000.) See also a paper titled ``Development of
Improved Injury Criteria for the Assessment of Child Restraint
Systems,'' that has been placed in the docket.
i. Head Injury
This NPRM proposes to replace the HIC 1000 limit in Standard No.
213 with the scaled HIC values adopted by the May 2000 air bag final
rule: 700 for 6-year-old dummy, 570 for the 3-year-old dummy; and 390
for the CRABI 12-month-old. In Standard No. 208, these values are
calculated over a 15 millisecond (msec) duration. We propose to
calculate HIC over a 15 msec duration (HIC15) for Standard
No. 213. Comments are requested on this issue, however, because while
HIC15 is appropriate for Standard No. 208, there currently
is no limit on the time duration used to calculate HIC in Standard No.
213. Generally speaking, limiting the time duration lowers the
calculated HIC values.
A. Should HIC Duration Be Limited to 15 Milliseconds?
We have previously declined to limit the time duration for
calculating HIC in Standard No. 213 compliance tests because of the
possible lessening of the stringency of the standard. Prior to the May
2000 rule on advanced air bags, Standard No. 208 limited HIC to 1000
but limited the calculation to a maximum time interval of 36 msec
(100036). In 1995, we were asked to amend Standard No. 213
to calculate HIC using a 36 msec time duration, as was done at the time
for Standard No. 208. The agency decided against limiting HIC because
we determined that HIC values were generally lower when the time
interval was limited to 36 msec (HIC36), compared to
HICunlimited (an unlimited time duration may be used to
calculate HIC). Given that a HIC36 limit could have reduced
the stringency of the standard, there was not enough information
justifying any limit on the time interval. Thus, NHTSA decided against
limiting HIC to 36 msec in Standard No. 213. 69 FR 35127, July 6, 1995.
Now, however, we are considering limiting the time interval for
measuring HIC in the child restraint standard. Standard No. 208 had
provided for calculating HIC for the entire crash duration as the child
restraint standard does now, but NHTSA limited the maximum time
duration of the HIC calculation to 36 msec for Standard No. 208 because
low acceleration crashes over a long time duration could exceed HIC
1000unlimited even though they were not likely to result in
brain injuries. The agency determined that limiting the duration over
which HIC is calculated to a maximum of 36 msec, while limiting HIC to
1000, assured that the acceleration level of the head will not exceed
60 g's for any period greater than 36 msec. The 60 g acceleration limit
was set as a reasonable head injury threshold by the originators of the
``Wayne State Tolerance Curve,'' which was used in the development of
the HIC calculation. 51 FR 37028; October 17, 1986.
The time interval was further reduced to 15 msec by the May 2000
final rule amending Standard No. 208. The May 2000 rule on advanced air
bags replaced 100036 with HIC 70015, based on
recommendations from motor vehicle manufacturers that the duration for
the HIC computations should be limited to 15 msec with a limit of 700
for the 50th percentile adult male dummy. NHTSA determined
that the stringency of HIC 70015 was equivalent to HIC
100036 for
[[Page 21824]]
long duration pulses, because while HIC15 produces a lower
numerical value for long duration events, its 700 lower failure
threshold compensated for the reduction.\15\ The final rule employed a
15 msec time interval whenever calculating the HIC function in Standard
No. 208, and limited the maximum response of the adult male dummy to
700 and the response of the smaller dummies to suitably scaled maximums
(700 for the 6-year-old, 570 for the 3-year-old, and 390 for the
CRABI).
---------------------------------------------------------------------------
\15\ In addition, the agency also believed that, for pulse
durations shorter than approximately 25 mses, the HIC
70015 requirement is more stringent than HIC
100036.
---------------------------------------------------------------------------
Since the TREAD Act directs us to consider adopting the scaled
injury criteria adopted by the May 2000 final rule on advanced air
bags, we are proposing that the HIC limits of 70015,
57015 and 39015 be incorporated into Standard No.
213 for tests with the 6-year-old, the 3-year-old and the CRABI,
respectively. NHTSA believes that it should take a cautious approach in
modifying the head injury tolerance level set by the HIC requirement.
Comments are requested on the appropriateness of both the scaled HIC
limits and on a 15 msec (or other) time interval for calculating HIC.
In cases of head contacts with softer surfaces, such as an airbag
system, the time duration of the contact is longer than in head
contacts with hard surfaces. Since HIC was initially developed for high
acceleration, short duration impact events, it is appropriate to limit
the HIC calculation in such airbag impacts, since the acceleration
levels are low but time duration is long and not similar to the
original intent of the HIC criterion. Data from sled testing of child
restraints conducted at the agency's Vehicle Research & Test Center
(VRTC) and from evaluating child restraints as part of the agency's New
Car Assessment Program (NCAP) show that there was not a major
difference between HICunlimited and HIC36,
indicating that the HIC responses are from contact events shorter than
36 msec. Further, accident data show that 79 percent of all brain
injuries for children 0-8 years old are due to contact, which would
imply the prevalence of short duration head acceleration events. This
finding appears to indicate a reasonable basis for making Standard No.
213's calculation of HIC consistent with Standard No. 208. Comments are
requested on whether the time interval should be limited to 15 msec, to
36 msec, or not at all. Limiting the time interval to 15 msec would
produce lower HIC values than the current method of calculating HIC in
Standard No. 213, but the reduction in HIC100036 to the
lower failure thresholds of 70015, 57015 and
39015 should achieve equivalent performance.
The agency does not know at this time the degree to which HIC
70015 and the scaled thresholds for the smaller dummies
would reduce the current HIC failure rate of Standard No. 213 because
data from past tests are unavailable in a format that allows us to
recalculate the relevant values. However, based upon agency test
results, we expect a high passage rate for HIC15. A series
of five rear-facing and five forward-facing tests were conducted at
VRTC with the CRABI dummy. In those tests, all five passed the
HIC15390 requirement in the rear-facing tests. Three of five
passed for the forward-facing tests. Forward facing tests with the
Hybrid III 3-year-old dummy have indicated 100 percent passage of the
HIC15570 requirement in Standard No. 213 conditions. A
series of nine sled tests conducted under the NCAP program at an
elevated sled test velocity of 35 mph also experienced a 100 percent
passage of the requirement; a series of 20 in-vehicle crash tests with
Hybrid III 3-year-old dummies conducted in NCAP produced over a 60
percent passage of the HIC15 requirement for these higher
speed impact test conditions. For the 6-year-old Hybrid III dummy, the
HIC15700 requirement was met 91 percent of the time in a
series of 11 tests. Based upon these results, the agency has
tentatively concluded that incorporation of the scaled HIC15
criteria for these Hybrid III child dummies would be reasonable.
Comments on test result experience of vehicle and/or child restraint
manufacturers with the Hybrid III child dummies and the scaled
HIC15 responses are sought.
B. Test Data
The agency conducted two series of tests to evaluate if the child
injury tolerance limits specified in FMVSS No. 208 are appropriate and
practicable for use in testing child restraints using Hybrid III child
dummies. The first series of sled tests was performed by VRTC to
determine the performance of typical forward-facing child restraint
systems secured by either a lap belt only, a lap and shoulder belt, or
the LATCH system (the child restraint's attachments were attached to
the child restraint by webbing material). The Hybrid III 3-year-old
test dummy was used in this testing. The child restraint systems were
installed and tested in either the rear seat of a contemporary sedan or
the seating assembly specified in FMVSS No. 213. In addition, three
sled acceleration pulses were studied: a typical Standard No. 208
frontal barrier crash (30 mph), an NCAP frontal crash (35 mph), and a
Standard No. 213 pulse. The results of the VRTC sled testing are
tabulated in Table 9 and discussed in a paper titled, ``Dynamic
Evaluation of Child Restraints Using Various Frontal Crash Pulses,''
which is available from the docket.
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[[Page 21826]]
The second series of tests were performed in 20 NCAP vehicle crash
tests to determine the performance of forward-facing child restraint
systems restrained in the rear seat by a lap and shoulder belt with top
tether and by a LATCH system (lower anchorages and top tether). The
Hybrid III 3-year-old test dummy was also used in this testing. The
results of these NCAP crash tests are tabulated and set forth in Table
10, infra.
Data from the VRTC sled tests and the NCAP full scale vehicle tests
suggest that the new Standard No. 208 head injury criteria,
HIC15 with its lower performance limit (570 for 3-year-old)
is equivalent to the current HICunlimited with a performance
limit of 1000. This conclusion is reached based upon the observation
that both the Hybrid II HICunlimited, and the Hybrid III
HIC15, responses in Standard No. 213 appear to comply with
their respective criteria limits with roughly a 50 percent margin.
ii. Thoracic Injury
A. Chest Acceleration
This document proposes new limits on chest acceleration and chest
deflection. Currently, Standard No. 213 limits chest acceleration to 60
g's. The May 2000 final rule on advanced air bags scaled this value to
55 g's for the 3-year-old dummy and 50 g's for the CRABI. The chest
acceleration limit remained at 60 g's for the 6-year-old dummy. We
propose incorporating the same limits into Standard No. 213. For the
12-month-old CRABI dummy, the agency has observed chest accelerations
of around 40 g's in rearward-facing child restraints. For forward-
facing restraints using the 12-month-old CRABI dummy, nearly 75 percent
of agency test results exceeded the 50 g limit, with accelerations
generally less than 55 g's. Chest acceleration responses for both the
3- and 6-year-old dummies were well below their respective criteria in
agency tests.
B. Chest Deflection
Currently, there is no chest deflection limit in Standard No. 213
because the current Hybrid II test dummies cannot measure chest
deflection. Incorporating the Hybrid III 6- and 3-year-old dummies into
Standard No. 213, as proposed in this NPRM, would enable us to measure
deformation-deflection of the thorax sternum. Because the dummies would
be capable of measuring this injury parameter, we propose that Standard
No. 213 include limits on chest deflection.
The May 2000 final rule on advanced air bags reduced the deflection
limit for the 50th percentile male dummy from 76 mm to 63 mm (from 3
inches (in) to 2.5 in). These limits were then scaled to obtain
equivalent performance limits for the 6- and 3-year-old dummies. The
CRABI does not measure chest deflection, so no limit was specified for
that dummy. Compression deflection of the sternum relative to the spine
was limited in Standard No. 208 to 40 mm (1.6 in) for the 6-year-old
dummy and 34 mm (1.3 in) for the 3-year-old dummy.
We propose the same limits for Standard No. 213, except for the
weighted 6-year-old dummy (see next section, below). Comments are
requested as to whether these limits are appropriate for testing child
restraint systems, particularly with respect to webbing systems and
impact shields that some child restraints use to restrain forward
movement of the child's torso.
C. Weighted 6-Year-Old Dummy
Based upon scaling considerations of increased mass of the thoracic
spine, greater chest compression limits appear to be justified for the
HIII-6CW since this dummy would represent either an 8-year-old, or an
80th- to 90th-percentile 6-year-old in weight and stature.
In evaluating chest acceleration, a pure mathematical evaluation
would indicate that accelerations should be somewhat lower for the
heavier dummy. However, considering that both the 5th- percentile
female and Hybrid III 6-year-old dummy have a 60g limit for injury
assessment purposes, the agency is reluctant to propose a reduction to
a lower g level for a dummy that is sized between the female and the
existing 6-year-old.
Accordingly, the agency proposes to incorporate a 42 mm deflection
limit for the weighted 6-year-old and a chest acceleration limit of 60
g.
D. Test Data
Data from the VRTC and NCAP tests indicate a high passing rate for
chest acceleration and deflection tests. In the VRTC frontal sled
tests, 94 percent of the tests of the LATCH seats (15 out of 16)
resulted in passing values for chest acceleration (average 43 g's), and
100 percent (17 out of 17) passed chest deflection (average 0.61 in).
For the non-LATCH seats, 76 percent (13 out of 17) passed chest
acceleration (average 47 g's) and 100 percent (16 out of 16) passed
chest deflection (average 0.73 in). These data suggest that the
Standard No. 208 chest acceleration and chest deflection limits are
practicable for child restraint systems.
iii. Neck Injury
Currently, there is no neck injury criterion in Standard No. 213,
because the current Hybrid II test dummies are not designed with neck
force measurement capability. However, the CRABI 12-month-old and the
Hybrid III 3- and 6-year-old dummies have been designed to measure neck
bending moments and forces in the fore and aft direction, and axial
compression and tension loads. Because the dummies are capable of
measuring neck injury parameters, we are proposing that the standard
include a new neck criterion.
The May 2000 final rule on advanced air bags specified limits for a
neck injury criterion, Nij, for the adult and child dummies used in
Standard No. 208 compliance testing. Nij is a new injury formula that
accounts for the combination of flexion, extension, tension and
compression. Nij accounts for the superposition of loads and moments,
and the additive effects on injury risk. Standard No. 208 includes an
additional, more stringent tension/compression limit to independently
control these potentially injurious loading modes in the air bag
environment to out-of-position children.
This NPRM proposes to incorporate an Nij criterion in Standard No.
213 that is the same as that specified in Standard No. 208, except that
the limit on peak tension and compression would not be adopted and the
``in-position'' critical values\16\ would be used for calculation of
the Nij. This decision is consistent with the agency's recognition of
in-position critical values in the Standard No. 208 final rule, and
with the observation that neck injury for children properly restrained
in child restraints is not as prevalent as for those positioned in
close proximity to an air bag at the time of deployment. A precise
determination of neck injuries to children in child restraints has been
difficult to quantify. When the NASS and FARS data are sorted to
examine neck injury for children restrained in a child restraint and
involved in a crash severity comparable to the Standard No. 213 sled
pulse, few neck injuries are observed. However, biomechanics
researchers have indicated to the agency that, although not frequent,
such injuries do occur under severe crash
[[Page 21827]]
conditions. In the agency's tests of child restraints, discussed below,
the Nij values calculated when applying the in-position critical values
ranged around Nij = 1. NHTSA has tentatively determined that Standard
No. 213 will incorporate the neck criterion of Nij = 1.0, where the
critical values are the in-position values shown in Table 10, and the
axial force is not limited. Comments are requested on this issue. NHTSA
also requests comments on the need for any type of neck injury
criterion at all in Standard No. 213, and the difficulty child
restraint manufacturers may have in meeting this new injury measurement
requirement.
---------------------------------------------------------------------------
\16\ The FMVSS No. 208 final rule proposed both ``out-of-
position'' and ``in-position'' critical values for Nij. The out-of-
position values are applicable to the air bag loading environment
where the loading to the neck is due to the occupant being out of a
normal seating position in close proximity to the air bag. In-
position critical values are applicable for conditions such as child
restraints, where the occupant is properly positioned and neck
forces and moments result from inertial loadings.
Table 10.--Nij In-Position Critical Values
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Nij intercepts
Dummy size -----------------------------------------------------------------------------------------------------------------------------------------------------------
Tension Compress Flexion Extension
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
CRABI............................... 1460 N (328 lbf)..................... 1460 N(328 lbf)...................... 43 Nm (32 lbf-ft).................... 17 Nm (13 lbf-ft)
3 YO................................ 2340 N (526 lbf)..................... 2120 N (477 lbf)..................... 68 Nm (50 lbf-ft).................... 30 Nm (22 lbf-ft)
6 YO................................ 3096 N (696 lbf)..................... 2800 N (629 lbf)..................... 93 Nm (69 lbf-ft).................... 42 Nm (31 lbf-ft)
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
iv. Tabulated Data
Table 9, supra, and the following table 11, set forth the data from
the NCAP tests. They show that meeting the Nij is practicable,
especially for LATCH seats, but that the neck measurements have little
compliance margin for Nij = 1.0. A detailed discussion of the findings
can be found in the technical paper, ``Dynamic Evaluation of Child
Restraints Using Various Frontal Crash Pulses,'' previously referenced
in this preamble.
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2. Static Testing Criteria
Certain changes to the requirements for which compliance is
measured in a static test seem appropriate by an incorporation of the
new test dummies.
Comments are requested on whether changes are needed to S5.2.3,
which specifies a padding requirement for child restraints used by
children weighing less than 22 lb. Should the requirement be deleted?
NHTSA specified the requirement (whose thickness and static compression
specifications are compliance-tested statically) because there was no
instrumented infant test dummy available at the time (1979) the
requirement was adopted. The agency's goal was to establish dynamic
test requirements for infant restraints, so that the total energy
absorption capability of the padding and underlying structure could be
measured. (44 FR 72131, 72135). Since today's NPRM proposes use of the
instrumented CRABI 12-month-old dummy for use in testing restraints
recommended for children under 22 lb, we propose deleting S5.2.3.
The standard refers to use of one or more Hybrid II dummies in some
of the static tests. These references would be
[[Page 21829]]
changed to the Hybrid III dummies or the CRABI. See, e.g., S5.2.1.2, on
use of the dummies to determine whether a seat back is required. See
also S5.4.3.5(b) and S6.2.3 (post-impact buckle force release). NHTSA
proposes to amend S6.2.3 so that the tension would be 90 N when a child
restraint is tested with the CRABI, and 350 N when a child restraint is
tested with the weighted 6-year-old dummy. Comments are requested as to
what other requirements should be changed.
VI. Proposed Effective Dates
TREAD requires us to complete this rulemaking by November 1, 2002.
Based on that date, the following section discusses tentative
conclusions about the dates on which compliance with the requirements
would become mandatory.
a. We believe that manufacturers could begin certifying thei