Children’s
Car
Seat
Restraints:
When
Top-Tether
Straps
Are
Ignored,
Are
These
Restraints
Safe?
Quentin H. McDonald, BA, MA
From The Bobby-Mac Company, lnc, Scarsdale, New York
The followingpaper written by the president ofone of the manufacturers of infant car seats will appear to some readers as self-serving advertisement. However, the reviewers and I both believe that the data are accu-rate and that the information is important for the pedia-trician and have, therefore, elected topublish this paper. Obviously, other manufacturers will be given equal op-portunity, if they have data to present.
R.J.H.
ABSTRACT. Children’s car seat restraints are impact
sled-tested to evaluate their safety qualities. To
deter-mine whether these restraints can protect the child, it is necessary to test in two different ways those restraints
that require a top-tether strap: (1) installed in accordance with the manufacturer’s directions; and (2) installed in
the manner they are actually used. In this study the five children’s car seat restraints top-rated by a leading con-sumer organization were impact sled-tested with a
top-tether strap in use. They were then tested without the top-tether strap-the way such restraints are often being
used as indicated by an Insurance Institute for Highway Safety survey. In addition, two leading restraints not requiring a top-tether strap, but secured by the auto lap
belt, were tested. This study shows that the five
top-tethered restraints, when installed with top-tether and lap belt, and the two restraints not requiring a top-tether give good protection in a frontal crash. It also shows that, with one possible exception, the five restraints that
re-quire a top-tether strap do not provide adequate protec-tion if the top-tether strap is not used. Pediatrics 64:848-855, 1979; accident prevention, automobile safety, child restraints, counseling.
Child safety is of major concern to all of us. Although it is encouraging that the incidence of deaths of children from seven preventable diseases
Received for publication, July 28, 1978; accepted March 7, 1979.
Reprint requests to (Q.H.M.) The Bobby-Mac Company, Inc, 95 Morris Lane, Scarsdale, NY 10583.
PEDIATRICS (ISSN 0031 4005). Copyright © 1979 by the
American Academy of Pediatrics.
(diptheria, pertussis, tetanus, polio, measles, ru-bella, mumps) has dramatically decreased to a mm-imal level within the past two decades, it is disturb-ing that the slaughter of young children on the
highways continues almost unabated.1 This is in
spite of the fact that we know injury and death of
children in automobiles can be substantially
re-duced by the correct use of properly designed child
restraints2’3 and by the use of auto lap belts.4
A contributing factor to the lack of progress in preventing death and injury to the child in the automobile has been the confusion that has existed, and continues to exist, as to just what is the best
way to restrain the child while riding in the
auto-mobile.
The US Department of Transportation took the first important step to protect the child passenger in April 1971, when it instituted Federal Motor Vehicle Safety Standard No. 213. This established a set of requirements that child restraints must meet, and it resulted in prohibiting the sale of the
most ineffective restraints.5 However, Standard 213
relies exclusively on static load testing of child restraints, a method that involves applying a load force of 1,000-lb pull on a wooden torso block
posi-tioned and/or harnessed in the restraint in
accord-ance with the restraint manufacturer’s directions. If the torso block moves more than 12 in, the restraint fails the test. Static load testing merely determines whether a restraint will hold together under a 1,000-lb pull. It in no way takes into account the dynamic forces at work in a real-life crash, nor does it give any indication of what happens to the occupant of
the restraint.
employing an impact sled on which an automobile seat is mounted. The sled is catapulted forward on a set of tracks; at the desired speed it impacts a barrier. Frontal crash tests are generally run at 30 mph and lateral tests at 20 mph. This method of testing requires an anthropometric test dummy to be harnessed in the child restraint according to the manufacturer’s directions.
Child restraints meeting the present Standard
213 but failing dynamic sled tests at 30 mph
con-tinue to be available on the market and are invari-ably the most reasonably priced restraints. These
units are still being purchased by unsuspecting
par-ents who confidently note that the restraint meets
or exceeds Standard 213, although the restraint is not necessarily crashworthy.7 During the years since the issuance of the original Standard 213 a number of safety-oriented institutions, organiza-tions, groups of physicians, and consumers tried to fill the dynamic-test-standard void with their own recommended lists of safe, dynamically tested child
restraints and helpful suggestions for child passen-ger safety. Some were factually based and know!-edgeably presented and were of significant help to the consumer; others only added to the confusion.8
One of the principal sources of consumer infor-mation on safe child restraints has been Consumers Union (CU). Since 1972 CU has published four car
seat evaluations. The most recent was issued in
June 1977. In this latest, 14 child restraints were rated according to the crash protection they provide
as judged by CU based on dynamic sled testing. The five restraints given the best marks all require a top-tether strap.9 A top-tether strap is an addi-tional strap attached to the top of the child re-straint; it is anchored: (1) to a specially installed bolt in the parcel shelf or cargo-area floor panel when the restraint is used in the rear seat of an automobile; or (2) over the back of the auto front
seat and onto a rear seat lap belt when the restraint
is used in the front seat. This latest CU evaluation, rather than simplifying the situation, actually cre-ated further confusion about child restraints. The CU report did not entirely disregard a study issued in 1975 by the Insurance Institute for Highway Safety but, unfortunately, it did not give this study proper emphasis.
The Insurance Institute study involved 5,050 cars containing at least one passenger under 10 years of age. Of 8,893 passengers under 10 years of age, 93% were not restrained, 16% of the child restraints observed were not used, and 73% of those in use were not used correctly. Of those restraints
requir-ing a top-tether strap, 47% of the tether straps were
not anchored.2 In the light of this report, immediate
concern was voiced because CU rated tether strap
restraints higher than restraints not requiring a
tether strap. Since one of the critical functions of a
child restraint is to limit head excursion to prevent contact with the automobile interior,’0 the concern
is whether top-tethered restraints can fulfill their
function when they are used without the top-tether strap.
The purpose of this study is to determine whether the protection provided by the five CU top-rated child restraints is reduced when the tether strap is not used, and if protection is reduced, to what extent.
METHOD OF TESTING
Selection of Occupant
A Sierra engineering anthropometric dummy,
37.5 in high, 32 lb in weight was used for all tests. The dummy approximated the size and weight of a 3-year-old child.
Test Environment
Tests were performed on an impact sled capable of simulating a crash, operating on rebound princi-ple. The restraints were mounted on a 1974 bench-type automotive adult seat.
Instrumentation and Data Handling Procedures
Seat belts and tether straps were preloaded to
17.5 ± 3.5 lb. Data were recorded simultaneously on
a Honeywell 7600 FM tape system and on a Hon-eywell 1612 light-beam oscillograph. High speed (1,000 ft/sec) 16-mm motion picture cameras posi-tioned to the side and overhead, plus a one-se-quence Polaroid camera were used to photograph each test.”
Test Matrix
Only frontal impacts were conducted on six of the restraints listed in the June 1977, Consumer Reports study, plus one restraint listed in previous Consumer Reports evaluations. All restraints tested were purchased in retail stores in Ann Arbor, MI, except for the Teddy Tot restraints, which could not be located and were obtained from the manu-facturer. All tests were 30 mph (21 g) impacts. Thirteen tests were performed, six with top-tether
straps secured, seven without top-tether straps
se-cured. No Bobby-Mac Company representative was present before, during, or after testing. All tests were conducted by Tandelta Associates, Inc, Ann Arbor, MI, at the facilities of the Highway Safety Research Institute of the University of Michigan in
July/August 1977.”
CRITERION FOR SAFE HEAD EXCURSION
A survey was conducted by the Bobby-Mac
TABLE. Sled Test Report Summary
Restraint Fig No. Maximum Absolute Evaluation per Test Report Head Excursion (in)
With Without Tether Tether 11.5 15.2 14.9 3 12.1 4 12.4 13.8
Teddy Tot Astroseat V 5
including compact and subcompact models. The distance between the forward-most point of the seat-back cushion of the front seat and the closest portion of the dashboard on the passenger’s side of the car was measured with the front seat in its full-forward position. The average of this measurement in these 43 autos was 21.4 in, the median 21.5 in. These data suggest that head excursion be limited to 21.5 in to be safe.’2
RESULTS OF TESTING
The five Consumers Union top-rated restraints (Strolee, Century, General Motors, Swyngomatic,
Strolee Wee Care Car Seat
2
Century Motor-Toter None
Safety Car Seat
None
General Motors Child None
Love Seat
Swyngomatic American None
Safety Child Safety Seat
None
6
Bobby-Mac 2-in-i Car None Seat
Bobby-Mac Deluxe Car 7
Seat
Teddy Tot), as well as the two Bobby-Mac
re-straints, were dynamically tested in 30-mph frontal
impacts with a 3-year-old size Sierra dummy. The
resulting head excursions (in inches), with and
with-out the top-tether straps secured (Bobby-Macs only
without tether), are listed in the Table together with Tandelta Associates evaluations of the per-formance of each restraint.”
The results of these tests are shown graphically in Figs 1 to 7. These figures are frames taken from
the high speed 16-mm films of the test crashes; each
illustration shows the position of that particular
restraint, and the dummy seated in it, at the very
height of the crash. Figs 1 through 4 show the
1. Head excursion excellent 2. Fair torso load distribution 25.7 1. Head excursion unacceptable
2. Very large shell deformation
1. Head excursion excellent 2. Overfiexion of the neck 3. Fair torso load distribution 24.9 1. Head excursion unacceptable
2. Shell deformation
3. Very poor torso load distribution
1. Head excursion excellent 2. Overfiexion of the neck 3. Poor torso load distribution
4. Tether strap pulled out of seat; did not have great effect on overall performance
1. Head excursion excellent
2. Overfiexion of the neck
-3. Fair torso load distribution
4. Seat back cracked at tether strap slot but did not
affect performance
27.0 1. Head excursion unacceptable 2. Shell deformation
3. Very poor torso load distribution 1. Head excursion excellent
2. Stomach shield high on torso during impact 3. Load distribution very poor
20.3 1. Head excursion good
2. Lap belt rode up high: loaded dummy’s chest 3. Very poor torso load distribution
4. Overfiexion of the neck
1. Head excursion excellent
2. Tether/harness brace on back of seat pulled out 3. Fair overall performance; fair load distribution 33.7 1. Head excursion uncontrolled and far above
ac-ceptable limits
2. Seat failed by total structural collapse 20.1 1. Head excursion good
2. Good torso load distribution
Figs 1 and 2. Strolee Wee Care Car Seat.
performance of two of the top-rated restraints when
used with the top-tether strap and when used
with-out the tether. Figs 5 and 6 are graphic crash evidence of what can happen to one of the
older-style tubular metal restraint types that have been,
and still are, widely available; this was also one of the Consumers Union top-rated restraints. Fig 7
shows the height of the test crash of a restraint that does not require a top-tether strap.
in-Figs 3 and 4. General Motors Child Love Seat.
creased appreciably when the tether straps were DISCUSSION not secured on those restraints that require them.
In fact, the head excursion allowed by four re- The evolution of dynamically tested child
re-straints increased sufficiently to propel the test straints is in its infancy. We are learning that there
Figs 5 and 6. Teddy Tot Astroseat V.
safety performance of a child restraint. Obviously
the best method, but the most difficult to achieve,
is to study and evaluate real-life accidents involving
children in child restraints. Until a greater fund of real-life accident data can be accumulated, how-ever, judgments must be drawn from dynamic
im-pact tests conducted in the artificial but controlled atmosphere of the laboratory. However, conclusions based on laboratory testing must be tempered by knowledge of how the restraint is actually being
used in real life, since the method of installing the
Fig 7. Bobby-Mac Deluxe Car Seat.
Williams2 of the Insurance Institute for Highway
Safety stated that “if child motor vehicle restraint
devices are not used correctly, they may not serve the purpose of restraining the child, and whatever crash protection they otherwise provide may be reduced or eliminated.” Shelness and Charles8 maintain that with respect to those restraints re-quiring top-tether straps, “ongoing scrutiny of re-straining devices in use shows that the majority are not anchored at the top.” Stalnaker’#{176} also maintains that “without these straps (top-tether and side
strap for side protection), the protection afforded
by those seats is greatly reduced.” This present
study substantiates conclusively what these experts
have maintained: if a safe child restraint requiring a top-tether strap is not properly installed in a car, the protection designed into the restraint is appre-ciably reduced.
IMPLICATIONS
It becomes obvious that the counseling of young
parents on the life-saving potential of child restraint
usage in the family auto must go beyond the mere
recommendation that a restraint be used. Since
improper use can markedly reduce a restraint’s
effectiveness, emphasis must be placed on correct
usage. Notwithstanding the variety of results shown in studies of safety education programs conducted
by pediatricians and hospitals,’32#{176} a major share of
the responsibility for restraint counseling must
con-tinue to rest with the pediatrician. After all, the pediatrician has early and repeated contact with the young parent and, most importantly, serves as the respected source of preventive medical advice for this parent. The participation of the pediatrician
is, therefore, critical to the furtherance of
automo-bile safety for the child. The more knowledge the
pediatrician has about child restraints, the more
effective this participation will be. Background
knowledge about restraints must be broad enough
to allow the pediatrician to match the type of
restraint to the motivation and responsiveness of
the parent in making restraint usage
recommenda-tions.
REFERENCES
1. United States Deaths from Specific Preventable Diseases and Automobile Accidents (Birth-24 Years). Irvington, NJ, Committee for a Safe Ride for Every Child, Physicians for
Automotive Safety, 1977
2. Williams AF: Observed Restraint Use of Children in Auto-mobiles. Washington, DC, Insurance Institute for Highway Safety, May 1975
3. Williams AF, Zador P: Injuries to Children in Automobiles in Relation to Seating Location and Restrzint Use.
Wash-ington, DC, Insurance Institute for Highway Safety, May 1976
Associ-ation for Accident and Traffic Medicine Resolutions. Jour-nal of Traffic Medicine/IAATM Newsletter. Stockholm,
January 1977
5. Federal Motor Vehicle Safety Standard 213, Child seating systems. Federal Register 35:14778, 1970
6. Federal Motor Vehicle Safety Standard 213-80, Child re-straint systems. Federal Register 43:21470, 1978
7. Cooney CE, Kummerow 5: Childsafe: when children travel by car, in Children Today. US Department of Health, Ed-ucation and Welfare Publication No. (OHD) 77-30014, July-August 1977, pp 11-15
8. Shelness A, Charles 5: Children as passengers in automo-biles: The neglected minority on the nation’s highways.
Pediatrics 56:271, 1975
9. Consumer Reports: Car Safety Restraints for Children.
Mount Vernon, NY, Consumers Union, June 1977, pp
314-317
10. Stalnaker RL: Tests of Current and Experimental Child Restraint Systems. New York, Society of Automotive Engi-neers (No. 740045), 1974, pp 1-26
1 1 A Report of Impact Tests Conducted for The Bobby-Mac Co, mc, Ann Arbor, MI, Tandelta Associates, Inc, August 7, 1977
12. Survey of 1977 Auto Seat Distances: Front Seat to Dash-board, Back Seat to Front Seat. Scarsdale, NY, The Bobby-Mac Co, Inc, 1977
13. Simons PS: Failure of pediatricians to provide automobile restraint information to parents. Pediatrics 60:646, 1977 14. Christophersen ER: Children’s behavior during automobile
rides: Do car seats make a difference? Pediatrics 60:69, 1977
15. Miller JR, Pless IB: Child automobile restraints: Evaluation of health education. Pediatrics 59:907, 1977
16. Reisinger KS, Williams AF: Evaluation of Three Educa-tional Programs Designed to Increase the Crash Protection of Infants in Cars. Washington, DC, Insurance Institute for Highway Safety, October 1977
17. Kanthor HA: Car safety for infants: Effectiveness of prenatal counseling. Pediatrics 58:320, 1976
18. Lieberman HM, Emmet WL, Coulson AH: Pediatric auto-motive restraints, pediatricians, and the academy. Pediatrics
58:316, 1976
19. Reichelderfer TE: A first priority-Childhood automotive safety. Pediatrics 58:307, 1976
20. Allen DB, Bergman AB: Social learning approaches to health education: Utilization of infant auto restraint devices. Pedi-atrics 58:323, 1976
TOO YOUNG TO PLAY??
Now recommendations from a six-year experimental sports study by the New
York State Public High School Athletic Association may lead schools
through-out the state and around the country to provide their students with the same
opportunities to excel outside their age group.
The study, involving 12,930 boys and girls from 722 public and private schools in New York State, dispels widely accepted educational theories about student
readiness for sports and places physical maturity, fitness, skill and prior sports
experience above age and grade level as criteria for eligibility in varsity sports. The injury rate of students who participated in the study was significantly lower than the state average for all students who compete in interscholastic
sports.
Submitted by Student
From Amdur, N: Scholastic study disproves age-old approach for gifted athletes. New York Times