Federal Register, Volume 64 Issue 129 (Wednesday, July 7, 1999)

[Federal Register Volume 64, Number 129 (Wednesday, July 7, 1999)]
[Proposed Rules]
[Pages 36657-36664]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-17235]

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DEPARTMENT OF TRANSPORTATION

National Highway Traffic Safety Administration

49 CFR Part 571

[Docket No. 99-5891]
RIN 2127-AH14

Federal Motor Vehicle Safety Standards; Child Restraint Systems

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

ACTION: Request for comments.

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SUMMARY: The agency is issuing this document to obtain information that
will help NHTSA determine whether Safety Standard No. 213, ``Child
Restraint Systems,'' should be amended in response to a petition for
rulemaking from Kathleen Weber of Ann Arbor, Michigan. The petition
concerns the availability of child booster seats for older children
(ages about 4 and older) that can be used in older cars whose rear
seats are equipped with only lap belts instead of both lap and shoulder
belts. To make it easier for child restraint manufacturers to produce
child restraints for these children, the petition asks that Standard
213 be amended such that compliance tests of booster seats may be
conducted with a top tether attached.
In the past, many drivers did not attach tethers when they used
tether-equipped child restraints in vehicles that lack user-ready
tether anchorages. Given that the vehicles in question lack user-ready
tether anchorages, the agency seeks comments on the extent to which
vehicle drivers would attach the booster seat's top tether. The agency
also seeks comments on the extent to which currently available vests,
harnesses, and other restraint systems (e.g., shoulder belt retrofits)
address the problem raised by the petitioner. Comments are requested on
the feasibility of redesigning boosters such that the restraints can
meet Standard 213's requirements when attached to the vehicle with only
a lap belt, and without the use of a tether.

DATES: You should submit your comments early enough to ensure that
Docket Management receives them not later than September 7, 1999.

ADDRESSES: You should mention the docket number of this document in
your comments and submit your comments in writing to: Docket
Management, Room PL-401, 400 Seventh Street, SW, Washington, DC, 20590.
You may call Docket Management at 202-366-9324. You may visit the
Docket from 10 a.m. to 5 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 National Highway
Traffic Safety Administration, 400 Seventh St., SW., Washington, DC.,
20590.

SUPPLEMENTARY INFORMATION:

Table of Contents

I. Background
a. The booster seats in question became unavailable after
upgrade to Standard 213
b. Petitioner seeks to make boosters available by allowing them
to be tethered in compliance test
c. The safety concern is that tethers often were not used in
vehicles lacking a user-ready tether anchorage, even by parents who
were aware of the importance of attaching the tether
d. The recent regulation requiring user-ready tether anchorages
to improve tether use will not apply to vehicles manufactured before
September 1999
II. Issues
III. Comments
Appendix A--Calspan Study
APPENDIX B-NHTSA TEST PROGRAM

I. Background

On December 4, 1997, Ms. Kathleen Weber of the University of
Michigan Child Passenger Protection Research Program, submitted a
petition for rulemaking to amend Federal Motor Vehicle Safety Standard
No. 213, ``Child Restraint Systems'' (49 CFR 571.213). The petition,
which NHTSA granted on January 30, 1998, concerns the manufacture of
booster seats that can be used by families using pre-1989 model year
vehicles. These vehicles have only lap belts in rear seating positions.
a. The Booster Seats in Question Became Unavailable After Upgrade
to Standard 213
Booster seats are designed for children who have outgrown a
convertible or toddler child restraint system. They are generally
designed for children who are about 4 to 8 years old. There are two
main types of booster seats currently produced. One type is called a
``shield booster'' due to use of a shield-like barrier to restrain the
upper torso of a child in a crash. Shield boosters attach to the
vehicle by the vehicle's lap belt (Type I belt) or lap belt portion of
a lap and shoulder belt (Type II belt). The other type of booster is
called a ``belt-positioning seat,'' which is a booster designed to use
both portions of a vehicle's Type II belt to restrain the child. A
belt-positioning seat is not directly attached to the vehicle seat, but
is held in place by the child's mass and the vehicle's Type II belt,
which is strapped over the child's lap and torso, just as the Type II
belt is used to restrain an adult occupant. A belt-positioning seat
must not be used with a vehicle's lap belt alone, since the seat lacks
structure or an internal belt to restrain the child's upper torso.
Shield booster seats, which are capable of being used with only a
vehicle's lap belt, were available in the past, but became unavailable
for children weighing over 18 kilograms (kg) (approximately 40 pounds,
lb) subsequent to an upgrade that NHTSA made to the standard pursuant
to the Intermodal Surface Transportation Efficiency Act (``ISTEA'') of
1991 (Pub. L. 102-240). That Act directed NHTSA to initiate rulemaking
on a number of safety matters, including child booster seat safety
(section 250). The legislative

[[Page 36658]]

history for the directive indicated that its impetus was a study
¹ that found that shield booster seats then manufactured
could not adequately restrain test dummies representative of the
children for whom manufacturers typically recommended for the seats. In
the study, the boosters could not adequately restrain a 22 kg (48 lb)
test dummy (representing a 6-year-old) when dynamically tested under
Standard 213. The boosters were ineffective at limiting head excursions
to within the requirements of Standard 213, and two of the boosters
failed structurally. The boosters also failed to prevent the ejection
of a 9 kg (20 lb) test dummy (representing a 9-month-old child) in the
dynamic test. These phenomena were observed notwithstanding the
recommendation of some booster seat manufacturers that their seats were
suitable for children weighing from 9 up to 32 kg (20 up to 70
lb).²
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\1\ Calspan Corporation (DOT HS 807 297, May 1988). A detailed
discussion of this study can be found in Appendix A to today's
document.
\2\ Because at that time only a 3-year-old dummy was used in
Standard 213's compliance test, the boosters could meet the standard
when tested with that dummy and were thus certified as complying
with the standard.
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In response to this study and to the ISTEA directive, NHTSA amended
Standard 213 to permit the manufacture of belt-positioning seats, which
were considered to be a new, superior type of booster seat (59 FR
37167, July 21, 1994). Belt-positioning boosters were believed to be
better able than shield boosters at accommodating a wider range of
child sizes. These boosters have since replaced shield boosters in the
marketplace, as many commenters to the rulemaking, including the
petitioner for this document, Kathleen Weber, had hoped they would.
NHTSA also incorporated the 6-year-old and 9-month-old dummies into the
standard's compliance test protocols, to ensure a more thorough
evaluation of the ability of a child restraint to adequately restrain
children recommended for the restraint, as compared to testing done
with only the 3-year-old dummy. Beginning in September 1996, any child
restraint recommended for children weighing over 18 kg (40 lb) must be
able to comply with the standard when tested with the 6-year-old child
dummy (60 FR 35126, July 6, 1995; 60 FR 63651, December 12, 1995).
Comments from manufacturers and others on the proposal to use the
6-year-old dummy in compliance tests did not indicate that shield
boosters manufactured at the time of the rulemaking could not comply.
To the extent there were any shield boosters that could not pass the
standard's requirements with the 6-year-old dummy, NHTSA anticipated
that manufacturers might (1) design their seats to achieve compliance
(such as by raising the height of the shield relative to the child's
torso), (2) relabel shield boosters as being suitable for children
weighing less than 18 kg (and thus avoid testing with the 6-year-old
dummy), or (3) replace production of shield boosters with belt-
positioning boosters. While the latter two responses to the final rule
have occurred, manufacturers have not redesigned shield boosters to
pass Standard 213 with the 6-year-old dummy. Thus, the shield boosters
manufactured today are not recommended for use by children over 18 kg
(40 lb).

b. Petitioner Seeks To Make Boosters Available by Allowing Them To Be
Tethered in Compliance Test

Petitioner does not want to see the renewed sale of shield booster
seats, because she does not believe the restraints provide adequate
upper torso restraint. Instead, the petitioner suggests that Standard
213 be amended to allow--

``hybrid'' toddler/booster restraints (forward facing with
internal harness/high-back belt-positioning booster) to be used by a
(20 kg) 45 lb child in the toddler mode with its internal harness
and installed with a lap belt and top tether strap.

The petitioner is referring to child restraints that can be used
with a Type I (lap) belt and with a Type II (lap/shoulder) belt. An
example of such a seat is Century's Breverra booster car seat, which is
recommended for children 14 to 27 kg (30 to 60 lb). The Breverra has a
removable 5-point harness system. When used with children weighing up
to 18 kg (40 lb), the Breverra is used with the 5-point harness, and
the restraint is secured to the vehicle seat by either a Type I or Type
II belt. (In vehicles equipped with Type II belt systems, a locking
clip may be required for proper installation of the restraint.) This
configuration (using the restraint system with children weighing up to
18 kg (40 lb), and restraining them with the internal 5-point harness)
is what the petitioner refers to as the ``toddler mode.'' The Breverra
is also designed for use as a belt-positioning seat with children 14 to
27 kg (30 to 60 lb). Parents are instructed to remove the 5-point
harness from the booster seat, and to use the car's Type II belt to
restrain the child. Because seats such as the Breverra are designed for
use both as a ``toddler seat'' and as a ``belt-positioning booster
seat,'' petitioner refers to them as ``hybrid'' restraints.
Petitioner seeks to permit hybrid restraints to be certified as
meeting the standard when recommended for children up to 20 kg (45 lb)
in the toddler mode (using the 5-point harness, attached to the vehicle
by lap belt). Currently, restraints recommended for children up to 20
kg are tested with the 6-year-old dummy. Hybrid restraints cannot meet
the head excursion limit, untethered, when tested with the 6-year-old
dummy in the toddler mode (using the 5-point harness). Presumably, they
can meet it tethered.
A number of parties have written to NHTSA in support of the
petition, including Safe Ride News and SafetyBeltSafe (both reiterated
the views of the petitioner). The American Academy of Pediatrics (AAP)
said that a high-back booster would help in physically restraining
young toddlers who can easily escape from Type II belts. The National
Transportation Safety Board (NTSB) expressed concern that the lack of
child restraints for older children complicates efforts to encourage
states to enact legislation to require children to ride in the back
seat. However, NTSB did not support measures that required use of a
tether or retrofitting a vehicle with a rear seat shoulder belt (these
approaches, and others, are discussed further below). NTSB hoped that
NHTSA will ``work with the child restraint manufacturers to expedite
efforts to provide child restraint systems for children who have
outgrown their convertible restraint systems to be used with lap-only
belts.''

c. The Safety Concern Is That Tethers Often Were Not Used in Vehicles
Lacking a User-Ready Tether Anchorage, Even by Parents Who Were Aware
of the Importance of Attaching the Tether

Tether use in vehicles not originally equipped with tether
anchorages has been very low in this country. Because of the low use
rate for tethers, NHTSA amended Standard 213 in 1986 to require
tethered child restraints to pass the 48 kph (30 mph) test without
attaching a tether (51 FR 5335). NHTSA amended the standard because
surveys that had been conducted for the agency consistently showed that
tethered restraints were used in those vehicles without the tether
strap attached more than 80 percent of the time. Seventy-eight (78)
percent of persons not using the tether strap knew that its use was
necessary for their child's protection, but still did not attach the
tether. Given the low level of tether strap use in vehicles lacking a
user-ready tether anchorage and the high level of awareness that the
strap must be used,

[[Page 36659]]

the agency did not believe that a tether strap could continue to be
permitted as a device necessary for the adequate protection of
children.
Child restraint harnesses and vests were not affected by the
rulemaking. This is because the potential for misuse of harnesses and
vests seemed to be significantly less than for tethered child seats.
With child harnesses and vests, it would be obvious to parents that if
the tether were not attached, the child would be completely
unrestrained in a crash. NHTSA also noted that its data on the non-use
and misuse of tethers did not study the extent to which the tethers are
improperly used on harnesses and vests. To date, harnesses and vests
are tested with the tether strap secured.

d. The Recent Regulation Requiring User-Ready Tether Anchorages to
Improve Tether Use Will Not Apply to Vehicles Manufactured Before
September 1999

To promote higher tether use, NHTSA has recently issued a final
rule that requires vehicle manufacturers to install factory-installed,
user-ready tether anchorages (with hardware) in new vehicles, beginning
September 1, 1999. ³ We believe, as do Canada and Australia,
that tether use improves when factory installed tether anchorages are
provided on vehicles as standard equipment. However, the requirement
for user-ready tether anchorages applies to vehicles manufactured on or
after September 1, 1999, and will not apply to the vehicles that are
the subject of the petition (older vehicles with only lap belts in rear
seating positions).
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\3\ The rule also amended Standard 213 to add a 720 millimeter
(mm) (28 inch) head excursion limit for forward-facing child
restraints, which manufacturers may meet by attaching a tether. The
existing 813 mm (32 inch) head excursion requirement will also have
to be met, with the tether unattached, to maximize head protection
even when the tether is not attached by a consumer.
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II. Issues

The agency seeks comments that will help it to assess whether NHTSA
should amend Standard 213 to permit booster seats, and possibly other
child restraint systems, to be tethered in determining compliance with
the head excursion requirements, and possibly with other requirements
as well.
NHTSA notes that the circumstances that gave rise to the petition
are diminishing. Vehicles manufactured in 1989 and after are required
to have Type II (lap and shoulder) belts installed in rear outboard
seating positions, enabling the use of belt-positioning booster seats,
with the Type II belts, for children weighing more than 18 kg. Pre-1989
vehicles are at the root of the issue, because they typically have no
Type II (lap and shoulder) belts in the rear seats. However, these
vehicles are steadily declining in number and eventually will be
replaced by vehicles with rear seat Type II belts.
This document sets forth below a number of requests for comments
and data. For easy reference, the requests are numbered consecutively.
In providing a comment on a particular matter or in responding to a
particular question, commenters should provide any relevant factual
information to support their conclusions, including but not limited to
cost and statistical data, and the source of such information.

Question 1. How Likely Are Tethers To Be Used in Vehicles That Lack
User-Ready Tether Anchorages?

Tether use in vehicles not originally equipped with tether
anchorages has been very low in this country. Are there data that show
that tether use in vehicles not originally equipped with a tether
anchorage will be greater than it has been in the past?
The petitioner's approach would delete the head excursion
requirement when the seat is tested untethered with the 6-year-old
dummy, i.e., in the manner that data show the seat is likely to be used
in a vehicle that did not have an originally-installed tether
anchorage. NHTSA conducted testing at our Vehicle Research and Test
Center (VRTC) in March 1998, to evaluate the performance of various
types of child restraints in limiting the amount of head excursion of
the 6-year-old dummy. The test program is discussed in Appendix B, and
a test report has been placed in the general reference docket for
Standard 213, NHTSA-99-5426. Our testing showed that untethered seats
were unable to meet the head excursion requirement. The seats generally
allowed between 795 and 851 mm (31.29 and 33.52 inches) of head
excursion. Nonuse of the tether will affect the possible advantages of
petitioner's suggested change.

Question 2: Is a Child Better Off in an Untethered Booster or Seated
Directly on the Vehicle Seat and Restrained by a Lap Belt? Are There
Alternative Approaches?

NHTSA's March 1998 testing program showed head excursions of the 6-
year-old dummy of up to 851 mm (33.52 inches) for untethered
restraints. Data are unavailable for head excursions for dummies
restrained only by a lap belt.
A preliminary study conducted by NHTSA, based on data from the
Fatality Analysis Reporting System (FARS) from 1988 through the first 6
months of 1997, compared the experience of unrestrained rear seat
occupants to some children using a lap belt only and to other children
using both lap and shoulder belts. The study found that for children
ages 5-14, use of a lap belt only while seated in a back outboard seat
of a car is 38 percent effective in reducing fatalities and use of a
back seat lap/shoulder belt is 52 percent effective in reducing
fatalities. The study shows that these children appear to derive the
greatest incremental benefit from using back seat lap/shoulder belts
rather than just a lap belt when compared to the other age and sex
groups evaluated in the study. In comparison, NHTSA estimates that
child restraints are potentially 71 percent effective in reducing the
likelihood of death.⁴
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\4\ Kahane, Charles J. (1986), An Evaluation of the
Effectiveness and Benefits of Safety Seats, U.S. Department of
Transportation, National Highway Traffic Safety Administration, DOT
HS 806 889, p. 305. The agency believes that this figure remains
valid.
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The same study also showed that, based on FARS and Multiple Cause
of Death (MCOD) data from 1988-1994, children ages 5-14 do not have an
increased risk of abdominal injuries compared to occupants in other age
groups. Lap belted and lap/shoulder belted children have abdominal
injury rates slightly higher than unrestrained children in frontal
crashes (12 and 15 per 100, respectively as compared to 9 per 100 for
unrestrained). These rates are at or below the injury rate of lap
belted and lap/shoulder belted occupants of all ages in frontal
crashes. However, the same data indicate that the head injury rate for
children ages 5-14 in the back seat in frontal crashes restrained by a
lap belt only is double that (50 versus 25 per 100) of those children
restrained with a lap and shoulder belt (and thus provided with upper
torso protection similar to what could be expected through the use of
child restraint systems).
Head excursions beyond that limited by Standard 213 reduce the
level of performance now required by 213. However, some believe that
using a lap belt without an upper torso restraint could result in
``seat belt syndrome,'' which refers to bruising across the abdomen,
internal injuries and lower spine fractures which, allegedly, are
caused mainly by a lap belt that is used incorrectly or that moves off
the child's pelvis during a crash. Are children restrained only by a
lap belt experiencing seat belt syndrome? Should we reduce the
protection required in the standard against head

[[Page 36660]]

impacts to broaden the protection against seat belt syndrome?
If there were no head excursion limit when a booster seat is tested
untethered with the 6-year-old dummy, this would seem to require no
more of booster seats than what is expected when the dummy is seated
directly on the vehicle seat and restrained by just a lap belt. An
alternative approach could be to increase Standard 213's head excursion
limit from 813 mm (32 inches) to 838 mm (34 inches) when testing a
booster seat untethered with the 6-year-old dummy. Under that approach,
there would be a limit to head excursion, even in the untethered
condition. Comments are requested on this approach.

Question 3: Should the Test That Evaluates Child Restraint Performance
Without Attaching the Tether Be Deleted for All Restraints, Not Just
Hybrid Toddler/Booster Restraints? Should the Test Be Deleted When
Testing With Dummies Other Than the 6-Year-Old?

If a tether were permitted to be attached when testing with the 6-
year-old dummy, should tethers be attached with testing with the 3-
year-old as well, such as when testing convertible child restraints
(which are usually recommended for children from birth to 18 kg (40
lb))? The agency believes that deleting the test for these other
restraints and in tests with other dummies is inadvisable at this time,
in the absence of data indicating whether tethers would be properly
used. However, what reasons would justify distinguishing between tether
use rates among hybrid boosters and other types of child seats or
otherwise justify why a tether could be attached for some restraints
and not for others?

Question 4: Why Are Shield Boosters No Longer Manufactured for Children
Weighing over 18 kg (40 lb)?

In the March 1998 test program at VRTC, the agency tested four
currently available types of shield booster seats with the 6-year-old
dummy. Two units of one of these shield boosters were tested, and in
each instance, they appeared to meet all performance criteria of
Standard 213, including the head injury criterion (HIC), chest
acceleration limits, and the head and knee excursion limits. Yet, the
booster was recommended for use by children only up to 18 kg (40 lb).
NHTSA later tested 3 other available shield-type booster seats using
the 6-year-old dummy and found that each exceeded the 813 mm (32 inch)
head excursion limit of Standard 213.
NHTSA requests information, particularly from child restraint
manufacturers, concerning the reasons why shield boosters are no longer
marketed for children weighing more than 18 kg (40 lb), especially with
respect to those boosters that appear to meet all performance criteria
of Standard 213. Were some manufacturers unable to certify that the
seats would meet Standard 213's requirements when tested with the 6-
year-old dummy? If they did so conclude, was it solely the head
excursion requirement, or other requirements as well? Were there test
failures, and if so, what were the margins of failure? Can shield
boosters be redesigned to achieve compliance with the standard? Why
have manufacturers not redesigned these boosters to achieve compliance?

Question 5: What Is the Feasibility of Redesigning Hybrid/Toddler
Booster Restraints Such That the Restraint Can Be Certified for Use
With Older Children, Without the Use of a Tether?

NTSB hoped that NHTSA will ``work with the child restraint
manufacturers to expedite efforts to provide child restraint systems
for children who have outgrown their convertible restraint systems to
be used with lap-only belts.'' NHTSA requests comments on the
feasibility of designing a hybrid booster seat such that the booster
can meet the current requirements of Standard 213 in the ``toddler
mode'' when tested with the 6-year-old dummy, and when attached to the
standard seat assembly with just a lap belt and without a tether.

Question 6: Is the Suggested Amendment Warranted When There Are
Products Now Available for Older Children That May Perform Better Than
a Tethered Seat at Limiting Head Excursion?

E-Z-On Products, Inc., manufactures vest and harness restraint
systems for use with a lap belt and tether. Vests and harnesses are
``child restraint systems'' under Standard 213 and are certified as
meeting all requirements of the standard.
The vest and harness systems employ a top tether to meet Standard
213's requirements. As explained above, Standard 213 permits a tether
on a vest or harness system (both are referred to as ``harnesses'' in
the standard) to be attached in the 48 km/h (30 mph) test, but does not
allow a tether to be attached on a conventional child restraint system
(such as a convertible child restraint or a high-back booster, such as
the Breverra). The reason for the different treatment is because it is
more obvious that a tether needs to be attached with vests and
harnesses than it is with conventional child seats. If a tether were
not used for a vest or harness, it would be clear to the parent that
the child's upper torso would have no restraint.
The E-Z-On Vest is designed to slip over the child, with a back
zipper closure. The vest is custom-made, using the child's waist
measurement. E-Z-On's Universal Harness is in the shape of an upside
down ``Y.'' There are two straps at the bottom of the upside down ``Y''
with loops at each end, that the lap belt is threaded through. The
upper part of the upside down ``Y'' has a tether hook which attaches to
the vehicle's tether anchor. E-Z-On has informed NHTSA that its vest
and harness systems are readily available through its distributors. A
vest or harness can be shipped to the consumer within 2 weeks. The
price of the vest is approximately $73 to $95, a cost comparable to
that of convertible seats. The harness costs approximately $45.
NHTSA's March 1998 test program at VRTC evaluated the performance
of various types of child restraints, including vests and harnesses,
hybrid boosters and convertible restraints, in limiting the amount of
head excursion of the 6-year-old dummy (see Appendix B). In brief, the
tethered vest and harness performed much better than the tethered
hybrid booster or tethered convertible restraint at limiting head
excursion. Test data for the tethered restraints were as follows:

Table 1.--Summary of Sled Test Results for Tethered Restraints
----------------------------------------------------------------------------------------------------------------
Head Knee
Restraint configuration HIC 3 ms chest excursion excursion Test No.
clip (G) (mm) (mm)
----------------------------------------------------------------------------------------------------------------
FMVSS No. 213 limit................... 1000 60 813 914
Century Breverra Contour/5-pt. Harness 332 38.9 760.22 904.49 UMP03
Lap Belt w/Top Tether.
Century Breverra Contour/5-pt. Harness 307 40.5 718.82 880.62 UMP05
Lap Belt w/Top Tether.
E-Z ON 86-Y Harness Lap Belt w/Top 463 52.5 495.30 540.26 UMP07
Tether.

[[Page 36661]]

E-Z ON 103Z Vest Lap Belt w/Top Tether 702 59.3 558.29 635.76 UMP08
E-Z ON 86-Y Harness Lap Belt w/Top 461 52.9 473.71 539.75 UMP09
Tether.
Britax Roundabout Lap Belt w/Top 270 42.3 622.55 798.83 UMP11
Tether.
Britax Roundabout Lap Belt w/Top 303 43.4 574.04 736.09 UMP13
Tether.
Britax Elite Lap Belt w/Top Tether.... 554 51.2 640.08 782.32 UMP15
Britax Elite Lap Belt w/Top Tether.... 614 58.9 580.39 719.84 UMP17
----------------------------------------------------------------------------------------------------------------

Based on this test program, NHTSA believes that vests and harnesses
could address petitioner's concerns and those of the other parties. The
E-Z-On Vest, with a back zipper closure, could address AAP's desire for
a product that can restrain young toddlers who have reached 18 kg (40
lb), but who are too immature behaviorally to use Type II belts. There
may be perceived drawbacks to vests and harnesses. A vest may not be as
convenient as a hybrid booster. The vest wraps around the child's torso
and has to be unclipped from the tether mounting strap to be placed on
a child. Also, vests and harnesses do not ``look like'' traditional
child restraint systems so they might not be as readily accepted by
some consumers as a tethered hybrid seat might be. Yet, owners of older
vehicles who are seeking any product to fix a perceived problem
concerning their youngsters may be more motivated to accept a harness
than consumers generally.
NTSB did not support measures that required use of a tether, given
the high non-use rates of tethers in this country. Yet, the likelihood
that parents will attach the tether on a harness could be higher than
that for conventional child seats, given that it would be more obvious
to a parent that the tether has to be attached on a vest or harnesses
than on a restraint such as a hybrid booster, which would be designed
to be used both with and without a tether, depending on the size of the
child occupant.
While the hybrid booster might be preferred by some consumers over
a vest or harness because of the expectations of consumers as to what a
child restraint system ought to look like, an untethered hybrid booster
does not restrict head excursion as well as a tethered vest or harness.

Question 7: Would Adoption of the Suggested Amendment Inappropriately
Encourage Some Parents To Position Restraints in the Center Rear
Seating Position?

Petitioner only addressed the need of consumers with pre-1989 cars,
but adoption of the suggested amendment could also affect the
preference of parents who wish to install a booster seat in the center
rear position. The center rear position typically has only a Type I
(lap) belt, not a Type II (lap and shoulder) belt system. Some of these
parents may welcome having booster seats that can be used in the center
rear seat with only a Type I belt. However, optimal performance of the
restraint is dependent on attachment of the tether. An untethered seat
in the center rear seat is not likely to perform as effectively as an
untethered belt-positioning booster used at the outboard seating
position with a Type II belt system. Would the suggested amendment
encourage consumers to move belt-positioning seats from outboard
seating positions to the center rear seat? How likely will consumers
attach a tether ⁵ when using the seat with children weighing
more than 18 kg (40 lb)?
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\5\ Our March 1999 final rule excludes belt-positioning seats
from the head excursion limit that requires a tether on the child
restraint. Thus, a belt-positioning seat that is not also a hybrid
toddler seat might not even have a tether.
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Question 8: What Is the Feasibility of Retrofitting a Rear Seat
Shoulder Belt in Pre-1989 Vehicles?

Retrofitting vehicles with a rear seat shoulder belt is another
option. While this approach is more expensive than installing a tether
anchorage (assuming there are structural elements for the tether
anchorage already in the vehicle), a shoulder belt can benefit children
who have completely outgrown a child restraint, and can also benefit
adults, seated in the rear. Many vehicle manufacturers offer shoulder
belt kits for rear seating positions, although availability and cost of
these kits vary widely. Because of the long term benefits associated
with this option as described above, we have suggested this approach to
many consumers who have contacted the agency in search of alternatives.
The majority of these consumers were unaware that vehicle manufacturers
offered such retrofit kits, and were generally very receptive to having
the retrofit kits installed in their vehicles. A minority expressed
reservations given the disproportionate cost of the retrofit kit parts
and installation when compared to the limited value of their older
vehicle.

III. Comments

How Do I Prepare and Submit Comments?

Your comments must be written and in English. To ensure that your
comments are correctly filed in the Docket, please include the docket
number of this document in your comments.
Your comments must not be more than 15 pages long. (49 CFR 553.21).
We established this limit to encourage you to write your primary
comments in a concise fashion. However, you may attach necessary
additional documents to your comments. There is no limit on the length
of the attachments.
Please submit two copies of your comments, including the
attachments, to Docket Management at the address given above under
ADDRESSES.

How Can I Be Sure That My Comments Were Received?

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

How Do I Submit Confidential Business Information?

If you wish to submit any information under a claim of
confidentiality, you should submit three copies of your complete
submission, including the information you claim to be confidential

[[Page 36662]]

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

Will the Agency Consider Late Comments?

We will consider all comments that Docket Management receives
before the close of business on the comment closing date indicated
above under DATES. To the extent possible, we will also consider
comments that Docket Management receives after that date.

How Can I Read the Comments Submitted by Other People?

You may read the comments received by Docket Management at the
address given above under ADDRESSES. The hours of the Docket are
indicated above in the same location.
You may also see the comments on the Internet. To read the comments
on the Internet, take the following steps:
(2) Go to the Docket Management System (DMS) Web page of the
Department of Transportation (http://dms.dot.gov/).
(3) On that page, click on ``search.''
(4) On the next page (http://dms.dot.gov/search/), type in the
four-digit docket number shown at the beginning of this document.
Example: If the docket number were ``NHTSA-1999-1234,'' you would type
``1234.'' After typing the docket number, click on ``search.''
(5) On the next page, which contains docket summary information for
the docket you selected, click on the desired comments.
You may download the comments. However, since the comments are
imaged documents, instead of word processing documents, the downloaded
comments are not word searchable.
Please note that even after the comment closing date, we will
continue to file relevant information in the Docket as it becomes
available. Further, some people may submit late comments. Accordingly,
we recommend that you periodically check the Docket for new material.

Appendix A--Calspan Study

Both of the rules that amended Standard 213 to permit the
manufacture of belt-positioning booster seats and to adopt new test
dummies into the standard for compliance tests responded to sections
2500-2509 of the Intermodal Surface Transportation Efficiency Act of
1991 (Pub. L. 102-240), which directed NHTSA to initiate rulemaking on
a number of safety matters, including child booster seat safety
(Sec. 2503). The legislative history for the directive indicated that
the directive evolved in large part from the findings of a study
entitled, ``Evaluation of the Performance of Child Restraint Systems,''
performed for NHTSA by the Calspan Corporation (DOT HS 807 297, May
1988). Congress believed that the study showed that some booster seats
``may not restrain adequately a child in a crash . . . .'' Senate
Committee on Commerce, Science, and Transportation, S. Rep. No. 83,
102d Cong., 1st Sess. 6, 18 (1991). Concerns about shield boosters had
arisen from the recommendations by child restraint manufacturers about
which children could appropriately use a particular booster. Particular
designs or models of boosters were typically recommended for a broad
range of children, often for children weighing from 9 to 32 kg (20 to
70 lb). At the time of the study, such a child restraint was tested for
compliance with Standard 213 with just the 3-year-old (15 kg) (33
pound) dummy. So tested, these restraints met Standard 213. However,
there were questions whether the boosters could provide adequate
protection for children at the extremes of the weight ranges that had
been recommended by the manufacturer as being suitable for the
restraint, i.e., those ranging from nine-month-old infants (average
weight 9 kg) to 6-year-old (22 kg) and older children.
In the Calspan program, the nine-month-old infant and the 6-
year-old child dummies were used in addition to the 3-year-old
dummy. The Calspan research program tested all 11 models of booster
seats that were on the market during the summer of 1987. In tests
with the 6-year-old dummy, Standard 213's 813 mm (32 inch) head
excursion limit was exceeded by 10 out of 11 booster seat models,
with measurements in the range from 813 to 899 mm (32.0 to 35.4
inches). One model ejected the dummy.
Following the Calspan study, NHTSA conducted additional research
on boosters. Nine booster seats were tested with the three dummies
used in the Calspan study. The seats met the performance measures of
Standard 213 when tested with the 3-year-old dummy. However, 7 of 9
allowed excessive head excursions with the 6-year-old dummy, and two
of the seats also had structural failures with the dummy.
``Evaluation of Booster Seat Suitability for Children of Different
Ages and Comparison of Standard and Modified SA103C and SA106C Child
Dummies,'' VRTC-89-0074, February 1990.

Appendix B--NHTSA Test Program

NHTSA developed and conducted a test program at VRTC from March
16-20, 1998, to evaluate the performance of various types of child
restraints in restricting the amount of head excursion of the 6-
year-old dummy. In developing this test program, NHTSA asked child
restraint manufacturers and the NTSB for suggestions as to which
approaches and products should be evaluated. One objective of this
test program was to obtain baseline information on the dynamic
performance of a ``typical'' shield-type booster seat, tested with
the 6-year-old dummy while secured to the vehicle seat by a lap belt
only. It is the presumed inability of this type of seat to meet the
813 mm (32 inch) head excursion requirement of Standard 213 that has
apparently resulted in child restraint manufacturers limiting these
restraints to use for children weighing no more than 18 kg (40 lb).
Pre-test discussions with restraint manufacturers confirmed that
Standard 213's head injury criterion (HIC), chest acceleration, and
knee excursion parameters did not pose concerns when testing this
type of restraint with the 6-year-old dummy. Rather, because of the
increase in height and weight of the 6-year-old dummy as compared to
the 3-year-old dummy--1168 versus 965 mm standing height (46 versus
38 inches), and 22 versus 15 kg in weight (48 versus 33 lb)--the
shield portion of the restraint apparently does not provide adequate
upper torso restraint to limit the head excursion within acceptable
limits when subjected to Standard 213's dynamic test. NHTSA chose
the Cosco Grand Explorer as a representative shield-type booster for
this baseline test.
The test program also evaluated a representative high-back belt-
positioning booster seat, utilizing its internal 5-point harness,
secured to the vehicle seat by a lap belt and a top tether. This
represents the specific configuration recommended in the Weber
petition. NHTSA chose the Century Breverra, which comes with an
optional top tether, as a representative seat for the test program.
NHTSA also tested a few convertible seats. Pre-test
conversations with restraint manufacturers indicated that there may
be some convertible restraints that are equipped with tethers that
may also perform adequately when attached to the vehicle seat with a
lap belt only, when restraining the 6-year-old dummy. Not all
convertibles are equipped with a top tether strap, and not all
convertible seats will be able to accommodate the 6-year-old dummy.
Britax Child Safety, Inc. indicated that they currently manufacture
two convertible restraints, the ``Roundabout'' which comes with a
standard top tether, and the ``Elite'' which comes with an optional
top tether attachment, which they felt would perform satisfactorily
in a crash test with the 6-year-old dummy with the restraint secured
to the vehicle seat by a lap belt and top tether. Accordingly, NHTSA
included each of these

[[Page 36663]]

convertible restraints in the subject test program.
Currently, the only commercially available products that are
marketed specifically for children weighing over 18 kg (40 lb) and
secured with a lap belt only are the Y-harness and vest systems
produced by E-Z On Products. Both of these systems require the use
of a top tether. The Y-harness system consists of two shoulder
straps which extend from the top tether anchorage, with looped ends
to allow the vehicle lap belt to be routed through and fastened over
the pelvic area. Similarly, the tether strap is attached to the vest
system by attaching the two snap hooks on end of the tether strap to
rings located on the shoulders of the vest, and the vehicle lap belt
is threaded through the web loops on the bottom of each side of the
vest. Both the Y-harness and the vest systems were included in the
test program for evaluation.
The dynamic sled tests were conducted at NHTSA's Vehicle
Research and Test Center, (VRTC), and were based on the test
conditions and procedures prescribed in S6 of Standard No. 213.
However, it must be emphasized that this test program was intended
for research only and did not precisely replicate compliance
testing. The VRTC tests evaluated the ability of the restraints at
limiting head excursion, HIC, chest acceleration, and knee
excursion. The test conditions were fixed throughout the sled test
series, with the only variable being the particular restraint being
tested and its attachment method (i.e. tethered or untethered). With
the exception of the baseline test utilizing the Cosco Grand
Explorer shield booster seat, each restraint was tested in each
attachment configuration on two separate sled runs to enhance the
repeatability of the test results. Two Cosco Grand Explorer
restraints were tested, but on the same sled run versus separate
sled runs as with the other restraints.
All tests were conducted using the 6-year-old dummy, and each of
the restraints--whether tethered or untethered--was attached to the
vehicle test seat using a lap belt only. Standard 213's limits are
as follows: HIC--1000; chest acceleration--60g; head excursion--813
mm (32 inches); and knee excursion--914 mm (36 inches). The full
test results are provided in Table 2. It is important to note that
in each of the tests conducted, values for both the HIC and chest
acceleration parameters were typically significantly below the
established limits prescribed in Standard 213 and that none exceeded
the maximum allowable limits.

Table 2.--Summary of Sled Test Results for All Restraints
----------------------------------------------------------------------------------------------------------------
Head Knee
Restraint configuration HIC 3 ms chest excursion excursion Test No.
clip (G) (mm) (mm)
----------------------------------------------------------------------------------------------------------------
FMVSS No. 213 limit................ 1000 60 813 914
Cosco Grand Explorer Lap Belt w/Sm. 424 32.9 697.74 614.17 UMP01
Shield.
Cosco Grand Explorer Lap Belt w/Sm. 417 32.2 748.79 660.15 UMP02
Shield.
Century Breverra Contour/5-pt. 332 38.9 760.02 904.49 UMP03
Harness Lap Belt w/ Top Tether.
Century Breverra Contour/5-pt. 273 30.8 851.41 925.83 UMP04
Harness Lap Belt; No Top Tether.
Century Breverra Contour/5-pt. 307 40.5 718.82 880.62 UMP05
Harness Lap Belt w/ Top Tether.
Century Breverra Contour/5-pt. 243 50.2 NA NA UMP06
Harness Lap Belt; No Top Tether *.
E-Z ON 86-Y Harness Lap Belt w/Top 463 52.5 495.30 540.26 UMP07
Tether.
E-Z ON 103Z Vest Lap Belt w/Top 702 59.3 558.29 635.76 UMP08
Tether.
E-Z ON 86-Y Harness Lap Belt w/Top 461 52.9 473.71 539.75 UMP09
Tether.
E-Z ON 103Z Vest Lap Belt w/Adj. 315 35.9 713.23 597.92 UMP10
CAM-Wrap.
Britax Roundabout Lap Belt w/Top 270 42.3 622.55 798.83 UMP11
Tether.
Britax Roundabout Lap Belt; No Top 477 39.3 810.26 895.60 UMP12
Tether.
Britax Roundabout Lap Belt w/Top 303 43.4 574.0 736.09 UMP13
Tether.
Britax Roundabout Lap Belt; No Top 425 36.1 794.77 864.36 UMP14
Tether.
Britax Elite Lap Belt w/Top Tether. 554 51.2 640.08 782.32 UMP15
Britax Elite Lap Belt; No Top 377 39.2 820.17 867.66 UMP16
Tether.
Britax Elite Lap Belt w/Top Tether. 614 58.9 580.39 719.84 UMP17
Britax Elite Lap Belt; No Top 377 43.1 821.69 878.08 UMP18
Tether.
Century Breverra Contour/5-pt. 299 31.2 843.79 917.96 UMP19 (Repeat of
Harness Lap Belt; No Top Tether UMP06)
(Repeat of UMP06).
----------------------------------------------------------------------------------------------------------------
* HIC based on head contact w/CRS as dummy slipped out of failed 5-pt. harness.

While NHTSA anticipated that shield-type boosters could not meet
the 32-inch head excursion limit of the standard when tested with
the 6-year-old dummy, test results showed that when tested in this
configuration, the Cosco Grand Explorer shield booster seats used
for the baseline testing satisfactorily limited head excursion to
under 762 mm (30 inches) in both instances. In addition, knee
excursion was measured to be 254 to 279 mm (10-11 inches) below the
914 mm (36 inch) limit. These test results are in direct contrast
with the Calspan and VRTC studies (see Appendix A, supra) conducted
in support of NHTSA's ISTEA rulemakings on booster seats.
Following conduct of the baseline test with the shield-type
booster seat, the agency tested the hybrid boosters and the
convertible seats both with and without the top tether strap. In the
tethered configuration, head excursion was measured to be below 762
mm (30 inches), and knee excursion was measured to be below the 914
mm (36 inch) limit (although only marginally so in one instance
(904.49 mm) (35.61 inches)). However, in each of the test runs
conducted using the untethered configuration, head and knee
excursions beyond the respective 813 and 914 mm (32 and 36 inch)
limits were measured, with marginal reductions in both the HIC and
chest acceleration parameters. It should be noted that a total of
three test runs was conducted using the untethered configuration, as
the test dummy slipped out of the child restraint during the second
test run due to a failure of the 5-point harness, voiding the
measurement of head and knee excursion. Interestingly, a comparison
between the untethered shield-type booster used in the baseline
testing and the tethered hybrid booster (forward facing with
internal harness/high-back belt-positioning booster) indicates that
the untethered shield booster performs marginally better (on
average) with respect to limiting head excursion and significantly
better with respect to limiting knee excursion than the hybrid
booster.
Two convertible restraints were evaluated in the same manner,
first with a top tether strap attached and then without. In the
tethered configuration, the Britax Roundabout limited head excursion
to 622.3 and 574.04 mm (24.5 and 22.6 inches) in the two tests
performed, well below the 813 mm (32 inch) limit prescribed in the
standard and also well below the results observed in the baseline
test with the shield-type booster. Knee excursion measurements were
also well below the established limit. However, whereas the
untethered hybrid toddler/booster restraint configuration resulted
in unacceptable head and knee excursions, the untethered Roundabout
configuration limited both head and knee excursion within acceptable
limits (although only marginally

[[Page 36664]]

with respect to head excursion in the first test at 810.26 mm (31.90
inches)). Additionally, while the untethered hybrid toddler/booster
restraint tests resulted in reduced HIC and chest acceleration
measurements, the untethered Roundabout tests resulted in reduced
chest acceleration measurements but increased HIC values.
The second convertible restraint, the Britax Elite, demonstrated
similar results. In the tethered configuration, head excursion was
limited to 640.08 and 580.39 mm (25.2 and 22.85 inches) in the two
tests performed, again well below the 813 mm limit prescribed in the
standard and also well below the results observed in the baseline
test with the shield-type booster. Knee excursion measurements were
also well below the established limit. However, each of the tests
conducted in the untethered configuration resulted in head excursion
measurements that marginally (820.02 and 821.69 mm) (32.29 and 32.35
inches) exceed the 813 mm limit, while knee excursion measurements
remained within acceptable limits.
The two different E-Z On products, the Y-harness and the vest,
are the only products currently marketed for children over 18 kg (40
lb) that do not require the use of a shoulder harness to attach to
the vehicle. Both of these systems require the use of a tether. Test
results show that the Y-harness system dramatically limited head
excursion to 495.3 and 473.71 mm (19.5 and 18.65 inches) on the two
tests, or approximately 33 percent below the 813 mm limit prescribed
in the standard, and significantly below the other tethered systems.
Knee excursion was also limited to values well below established
limits.
E-Z On markets two different styles of the vest system. The
first is an adjustable vest, which can be adjusted for fit as the
child grows via three different zipper locations on the back of the
vest. This was not used in this test program, as the vest, when
configured in its smallest size, was still too large to properly fit
the 6-year-old test dummy. E-Z On also manufactures sized vests,
provided to the consumer based on anatomical measurements of the
child as provided to E-Z On. NHTSA utilized a fitted vest in this
testing program, although it should be noted that the vest provided
by the manufacturer for this testing was very tight on the 6-year-
old dummy, and the next larger size would likely have provided a
better fit. The E-Z On vest system was tested utilizing a top tether
strap. The head and knee excursion values were both well below
established limits. The chest acceleration was 59.3 g, marginally
below the limit of 60 g. This high value for chest acceleration may
be partially attributable to the very snug fit of the vest on the
test dummy.
Given the excessive head excursion measured in 17 of the 20
tests performed in the Calspan and VRTC studies, combined with the
assumption that child restraint manufacturers are not currently
marketing shield-type booster seats for children over 18 kg due to
an inability to meet the head excursion requirement when testing
with the 6-year-old dummy, NHTSA chose to include only one
representative shield-type booster seat (the Cosco Grand Explorer)
to serve as a baseline test for the current test program. However,
given the favorable results with respect to both head and knee
excursion parameters seen with this seat as noted above, NHTSA
conducted a second set of testing to evaluate three other currently
available shield-type booster seats (the Gerry Double Guard, Evenflo
Sidekick, and Fisher Price T-Shield). As before, each seat was
tested twice, on separate test runs, to enhance the repeatability of
the test results. In each instance, the measured head excursion
significantly exceeded the 813 mm (32 inch) limit of Standard 213,
ranging from 876.3 to 1016 mm (34.5 to 40.0 inches). Full test
results are provided in Table 3. These results more closely parallel
those recorded in the earlier tests conducted by Calspan and VRTC.
Physical examination of each of the four shield-type booster seats
tested in this test program revealed no obvious, discernable
variations in construction, i.e., height of the shield, etc., that
would explain the difference in performance of the Cosco Grand
Explorer versus the others with respect to head excursion.

Table 3.--Additional Shield Booster Tests
----------------------------------------------------------------------------------------------------------------
Head Knee
Restraint configuration HIC 3 ms chest excursion excursion Test No.
clip (G) (mm) (mm)
----------------------------------------------------------------------------------------------------------------
FMVSS No. 213 limit.................. 1000 60 813 914 ..................
Gerry Double Guard Lap Belt w/sm. 748 35.8 979.9 825.5 UMP21
Shield.
Evenflo Sidekick Lap Belt w/sm. 721 37.8 873.8 762.0 UMP22
Shield.
Fisher Price T-Shield Lap Belt w/sm. 349 26.1 927.1 767.1 UMP23
Shield.
Evenflo Sidekick Lap Belt w/sm. 820 35.9 876.3 749.3 UMP24
Shield.
Gerry Double Guard Lap Belt w/sm. 780 34.6 1016 838.2 UMP25
Shield.
Fisher Price T-Shield Lap Belt w/sm. 525 31.5 955.0 784.9 UMP26
Shield.
----------------------------------------------------------------------------------------------------------------

Issued on June 29, 1999.
L. Robert Shelton,
Associate Administrator for Safety Performance Standards.
[FR Doc. 99-17235 Filed 7-6-99; 8:45 am]
BILLING CODE 4910-59-P