DOT HS 809 671
`
`January 2004
`
`Misuse of
`Child Restraints
`
`This document is available to the public from the National Technical Information Service, Springfield, Virginia 22161
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`Page 1 of 64
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`Nuna Exhibit 1013
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`This publication is distributed by the U.S. Department of Transportation, National Highway
`Traffic Safety Administration, in the interest of information exchange. The opinions, findings
`and conclusions expressed in this publication are those of the author(s) and not necessarily those
`of the Department of Transportation or the National Highway Traffic Safety Administration.
`The United States Government assumes no liability for its content or use thereof. If trade or
`manufacturers’ names or products are mentioned, it is because they are considered essential to
`the object of the publication and should not be construed as an endorsement. The United States
`Government does not endorse products or manufacturers.
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`Page 2 of 64
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`1. Report No.
`
`DOT HS 809 671
`4. Title and Subtitle
`
`
`Misuse of Child Restraints
`
`2. Government Accession No.
`
`
`13. Type of Report and Period Covered
`Final Report
`October 2001-May 2003
`14. Sponsoring Agency Code
`
`7. Authors
` Lawrence E. Decina and Kathy H. Lococo
`
`9. Performing Organization Name and Address
`TransAnalytics, LLC
`1722 Sumneytown Pike
`Box 328
`Kulpsville, PA 19443
`12. Sponsoring Agency Name and Address
`
`Office of Research and Technology
`National Highway Traffic Safety Administration
`400 Seventh Street, S.W., Room 5119
`Washington, DC 20590
`15. Supplementary Notes
`
`COTR: Alan Block, NTI-131
`16. Abstract
` The purpose of this study was to obtain a measure of the current level of misuse of child restraint systems
`(CRSs) among the general public. The project focused specifically on forms of misuse that can be expected
`to raise the risk of injury. CRS use and critical misuse data were collected in the Fall of 2002 for 5,527
`children weighing less than the driver-estimated weight of 80 lb in 4,126 vehicles in 6 States: Arizona,
`Florida, Mississippi, Missouri, Pennsylvania, and Washington.
`
` Results showed that 62.3 percent of these children were restrained in a CRS; 25.9 percent were restrained
`in a safety belt (SB); and 11.8 percent were unrestrained. By weight class, CRS use was 97.1 percent for
`children less than 20 lb; 86.4 percent for children 20 to 39 lb; 41.7 percent for children 40 to 59 lb; and 10.9
`percent for children 60 to 79 lb.
`
` Overall critical CRS misuse was 72.6 percent. Most common critical misuses were loose harness straps
`securing the child to the CRS and loose vehicle SB attachment around the CRS. Other types of CRS
`misuses were also observed and recorded in the study. A positive relationship was found between drivers
`using safety belts and children being restrained—91.7 percent of the children who were transported by
`belted drivers were restrained in either a child restraint system or a safety belt, compared to 62.3 percent of
`the children transported by unbelted drivers. Recommendations are provided for periodic monitoring of
`CRS misuse, research needs, and enforcement and education.
`17. Key Words
`18. Distribution Statement
`car seat data collection
`This document is available to the public
`child passenger safety (CPS) field observations
`through the National Technical Information
`child restraint system (CRS) safety belt (SB) use
`Service, Springfield, VA 22161.
`critical CRS misuse unrestrained
`CRS use
`19. Security Classif. (of this report)
`21. No. of Pages
`
`20. Security Classif. (of this page)
`55
`Unclassified
`Unclassified
`Form DOT F 1700.7 (8-72)
` Reproduction of completed page authorized
`
`3. Recipient's Catalog No.
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`5. Report Date
` May 2003
`
`6. Performing Organization Code
`
`8. Performing Organization Report No.
`
`
`10. Work Unit No. (TRAIS)
`
`11. Contract or Grant No.
`DTNH22-01-H-05180
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`22. Price
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`Page 3 of 64
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`PREFACE
`
`
`
`The objective of this project was to obtain a measure of the current level of misuse of
`child restraint systems (CRSs) among the general public. The project focused specifically on
`forms of misuse that can be expected to raise the risk of injury. Over 4,100 vehicles and over
`5,500 children weighing less than the driver-estimated weight of 80 lb, from 6 States (Arizona,
`Florida, Mississippi, Missouri, Pennsylvania, and Washington), were observed in the study. Data
`were collected in the Fall of 2002.
`
`The authors wish to thank many individuals and organizations for their time and effort.
`The authors would first like to express their appreciation to the State site coordinators (SSCs)
`who were responsible for field operations in their respective States. They are Nancy Avery
`(Tucson SAFE KIDS), Kay Brodbeck and Cynthia Huff (Mississippi Safety Services), Kathy
`Kruger (Washington Safety Restraint Coalition), Cathy Metzger (SAFE KIDS St. Louis), Juli
`McGreevy (Pennsylvania consultant), Robert Mott (South Central Pennsylvania Highway Safety
`Program), and Lorrie Walker (Florida Traffic Safety Resource Center, Florida Atlantic
`University).
`
`Thanks are in order to the expert panelists who attended the workshop to identify the
`criteria for measuring critical CRS misuse early in the project. They are Paul Butler (Ford
`Automobile Safety Office), David Campbell (David Campbell and Associates), Karen DiCapua
`(National Safe Kids Campaign), Dr. Susan Ferguson (Insurance Institute for Highway Safety),
`William Hall (Highway Safety Research Center, University of North Carolina), Lorrie Walker
`(Florida Traffic Safety Resource Center, Florida Atlantic University), Kathleen Weber
`(University of Michigan Medical School, retired), and Dr. Narayan Yoganandan (Medical
`College of Wisconsin).
`
`Thanks are also in order to Dr. Flaura K. Winston, Shannon D. Morris, and Rebecca A.
`Cornejo of Children’s Hospital of Philadelphia for their contributions at the workshop. In
`addition, thanks are in order to Chesapeake Research Review, Inc. (Columbia, Md.) for
`conducting the institutional review board procedures and approval.
`
`Final thanks to the dozens of certified child passenger safety technicians and instructors,
`as well as greeters responsible for collecting quality CRS misuse data in the six States. Also
`thanks to our data entry staff. They were Amy Richmond, Ann Scheeler, and Elizabeth Standish.
`
`
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`ii
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`TABLE OF CONTENTS
`
`INTRODUCTION ...............................................................................................................5
`
`
`EXECUTIVE SUMMARY .............................................................................................................1
`
`1.0
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`2.0
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`3.0
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`1.1
`
`BACKGROUND .....................................................................................................5
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`1.2
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`PROJECT OBJECTIVES AND SCOPE OF WORK............................................12
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`RESEARCH METHODOLOGY.......................................................................................15
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`2.1 WORKSHOP TO IDENTIFY CRS MISUSE MEASURES (BASED ON
`INJURY SEVERITY)............................................................................................15
`
`2.2
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`2.3
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`2.4
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`2.5
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`2.6
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`2.7
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`2.8
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`2.9
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`CRITERIA FOR SITE SELECTION ....................................................................16
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`STATE AND GEOGRAPHIC REGION SITE SELECTION ..............................17
`
`TRAIN-THE-TRAINER WORKSHOP ................................................................18
`
`DATA COLLECTION INSTRUMENTS .............................................................19
`
`INSTITUTIONAL REVIEW BOARD..................................................................20
`
`FIELD PERSONNEL ............................................................................................20
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`TRAINING ............................................................................................................20
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`DATA COLLECTION ..........................................................................................21
`
`2.10 SITE CHARACTERISTICS..................................................................................22
`
`2.11 DATA ANALYSIS................................................................................................23
`
`RESULTS AND ANALYSIS............................................................................................25
`
`3.1
`
`3.2
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`3.3
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`3.4
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`3.5
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`SAMPLE SIZE CHARACTERISTICS.................................................................25
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`VEHICLE SEATING POSITION OF CHILDREN..............................................26
`
`CHILD RESTRAINT SYSTEM (CRS) USE........................................................26
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`CHILD RESTRAINT SYSTEM (CRS) MISUSE.................................................31
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`HARNESS RETAINER CLIP MISUSE ...............................................................35
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`iii
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`4.0
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`TABLE OF CONTENTS (Continued)
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`3.6
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`3.7
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`3.8
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`3.9
`
`OTHER CHILD RESTRAINT SYSTEM (CRS) MISUSE TYPES AND
`LATCH USE..........................................................................................................35
`
`SAFETY BELT (SB) ONLY USE BY CHILDREN ............................................36
`
`UNRESTRAINED CHILDREN............................................................................36
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`DRIVER CHARACTERISTICS ...........................................................................36
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`3.10 AIR BAG SYSTEM CHARACTERISTICS.........................................................37
`
`SUMMARY AND RECOMMENDATIONS....................................................................39
`
`4.1
`
`SUMMARY...........................................................................................................39
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`4.2
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`RECOMMENDATIONS.......................................................................................41
`
`REFERENCES ..................................................................................................................45
`
`“CRS Correct Use Definitions” Guidesheet (for Observers) ................................49
`
`Greeter Form..........................................................................................................51
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`Observation Form ..................................................................................................53
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`Socio-Economic Characteristics of State Sites (County-Level) ............................55
`
`
`5.0
`
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`APPENDICES
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`A
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`B
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`C
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`D
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`Table 1
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`Table 2
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`Table 3
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`Table 4
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`LIST OF TABLES
`
`Child restraint laws of States in the study (as of September 2002) .......................18
`
`Safety belt laws of States in the study (as of September 2002).............................18
`
`Number of sampled vehicles and children (State and total) ..................................25
`
`Number of sampled children, by weight (State and total). ...................................25
`
`iv
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`LIST OF TABLES (Continued)
`
`Number of sampled children, by age (State and total)...........................................26
`
`Number of sampled children by type of restraint used (State and total) ...............26
`
`Type of restraint used by weight............................................................................27
`
`Comparison of current and past NHTSA CRS misuse observation studies.
`(Children less than 60 lb only data) .......................................................................27
`
`Type of restraint used by age.................................................................................28
`
`Type of child restraint used by weight...................................................................30
`
`Type of child restraint used by age .......................................................................30
`
`
`
`Percentage of CRSs exhibiting critical misuses, by CRS type ..............................31
`
`Critical misuses of infant seats ..............................................................................33
`
`Critical misuses of rear-facing convertible seats. ..................................................33
`
`Critical misuses of forward-facing convertible seats.............................................33
`
`Critical misuses of forward-facing only seats........................................................34
`
`Critical misuses of belt-positioning booster seats..................................................34
`
`Critical misuses of shield boosters.........................................................................34
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`Critical misuses of forward-facing integrated seats...............................................34
`
`Harness retainer clip misuse by CRS type.............................................................35
`
`
`Table 5
`
`Table 6
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`Table 7
`
`Table 8
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`Table 9
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`Table 10
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`Table 11
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`Table 12
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`Table 13
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`Table 14
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`Table 15
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`Table 16
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`Table 17
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`Table 18
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`Table 19
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`Table 20
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`v
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`Page 8 0f 64
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`vi
`vi
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`Page 8 of 64
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`EXECUTIVE SUMMARY
`
`
`This study was conducted for the National Highway Traffic Safety Administration
`
`(NHTSA). The purpose of this study was to obtain a measure of the current level of misuse of
`child restraint systems (CRSs) among the general public. The project focused specifically on
`forms of misuse that can be expected to raise the risk of injury.
`
`
`RESEARCH METHODOLOGY AND DATA COLLECTION
`
`Key research task activities included: (1) conducting a workshop with National experts
`
`on CRS misuse, injury prevention, and crash data to develop appropriate critical misuse
`measures; (2) selecting State sites and State site coordinators (SSCs) in six States; (3) holding a
`train-the-trainer workshop with SSCs and their field site managers (FSMs) to finalize CRS
`misuse definitions and data collection instruments, and to discuss recruitment and training
`techniques; (4) conducting field observations; (5) conducting data entry and analysis; and (6)
`preparing the final report.
`
`A workshop was held within five months of the project start date with leading medical,
`
`bioengineering, and injury prevention experts in the field. The workshop included discussions
`on types of child injury severity in crashes; identification of the types of CRS misuse and their
`relationship to serious injury; and identification of the most important CRS misuse measures to
`include in data collection. Areas identified for critical CRS misuse measures in the workshop
`were: age and weight appropriateness of CRS; direction of CRS; placement of CRS in relation to
`air bags; installation of CRS to the vehicle seat; secureness/tightness of harness straps and crotch
`strap of the CRS; secureness/tightness of the vehicle safety belt (SB) to the CRS; locking clip use
`for vehicle SBs; fit of SBs across the children in belt-positioning booster seats; and damaged
`CRSs.
`
`Six States (Arizona, Florida, Mississippi, Missouri, Pennsylvania, and Washington) were
`
`selected as data collection sites. States were selected based on their representing diverse
`geographic regions across the country; and encompassing diversity in socio-demographic and
`economic characteristics across field sites. The field sites included urban, suburban, and rural
`areas. It was critical for each State to have a qualified and experienced State Site Coordinator
`(SSC) who was familiar with managing field observations and could easily gain permission to
`conduct observations at sites in their area. State regional areas included Tucson (AZ); Boca
`Raton, Fort Myers, Fort Pierce, and Miami (FL); Jackson (MS); St. Louis (MO); Carlisle, and
`Harrisburg (PA); and Seattle and Tacoma (WA). Field observation sites were primarily parking
`areas at community shopping centers, child merchandise department stores, fast food restaurants,
`health and medical facilities, and community events.
`
`A train-the-trainer workshop was held with SSCs and FSMs approximately one month
`
`before data collection to finalize CRS misuse definitions and data collection instruments. The
`workshop also covered recruitment of greeters and field observation staff; training techniques;
`data collection procedures; and project administration details.
`
`
`
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`1
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`Most sites conducted recruitment and training of staff in September 2002. It was
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`required that all field observers be AAA certified CPS technicians. Data were collected from
`late September 2002 to early January 2003. Most of the States completed their data collection
`efforts by mid-November 2002. Project staff checked quality of data on a daily basis for the first
`two weeks and then weekly. Data entry and analysis were then conducted. A summary of the
`results was presented to NHTSA before the completion of the draft final report.
`
`RESULTS
`
`A total of 4,126 vehicles and 5,527 children weighing less than the driver-estimated
`
`weight of 80 lb were included in the study. There were 511 children weighing less than 20 lb;
`2,483 children weighing 20 to 39 lb; and 2,533 children weighing 40 to 79 lb. By age category
`there were 676 children less than 1 year of age; 2,021 children from the ages of 1 through 3;
`2,571 children from ages 4 through 8; and 259 children ages 9 and older.
`
`
`For the total sample of children weighing less than 80 lb, 62.3 percent were restrained in
`CRSs, 25.9 percent were restrained in SBs, and 11.8 percent were unrestrained. CRS use by
`weight classification was as follows: 97.1 percent for children weighing less than 20 lb; 86.4
`percent for children weighing 20 to 39 lb; 41.7 percent for children weighing 40 to 59 lb; and
`10.9 percent for children weighing 60 to 79 lb. Safety belt (SB) use increased markedly for
`children 40 lb and over. SB use was 43.1 percent for children weighing 40 to 59 lb; and 64.9
`percent for children weighing 60 to 79 lb. By age category, CRS use was 97.3 percent for
`children younger than 1 year, 90 percent for children ages 1 through 3, 37.2 percent for children
`ages 4 through 8, and 3.1 percent for children ages 9 and older. SB use increased markedly for
`children 4 through 8 years of age to 45.5 percent.
`
`One or more critical misuses were found in 72.6 percent of all CRSs observed.
`
`Percentages of CRSs with critical misuses by seat type were as follows: infant (83.9 percent);
`rear-facing convertible (83.5 percent); forward-facing convertible (81.9 percent); forward-facing
`only (79.3 percent); belt-positioning booster (39.5 percent); and shield booster (60.5 percent).
`
`The most common critical misuses were loose harness straps securing the child to the
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`CRS and loose SB securing the CRS to the vehicle. Harness retainer clip misuse was also
`prevalent, but not deemed as a critical misuse in this study.
`
`Other CRS misuse problem areas were also observed. They included visible damage to
`
`the CRS (e.g., cracked seat shell, torn harness strap, broken harness parts); percent of CRS base
`(bottom of seat) contacting the vehicle seat; and presence of aftermarket devices.
`
`Forty-two observations of LATCH (Lower Anchors and Tethers for CHildren) were
`
`noted. Field observers found three seats with improperly used lower anchors, and three seats
`with improperly used tethers. Six seats were observed with both a safety belt and the lower
`anchors in use.
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`Children being transported by drivers who are restrained in SBs are more likely to be
`
`restrained than children who are being transported by unrestrained drivers. Of the observed
`
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`drivers, 77.4 percent were restrained. When drivers were wearing a SB, 91.7 percent of children
`were restrained in either a CRS (44.2 percent) or SB (47.5 percent). When drivers were not
`restrained, only 62.3 percent of children were restrained in either a CRS (43.2 percent) or SB
`(19.1 percent).
`
`Air bag systems were also observed. Driver frontal air bags were noted in 83.1 percent of
`
`the vehicles; passenger frontal air bags were found in 71.8 percent of the vehicles. Side air bags
`protecting passengers in the front seat were observed in 4.6 percent of the vehicles, and side air
`bags protecting passengers in both the front and rear seats were observed in 1.3 percent of the
`vehicles. Only a small percentage of the vehicles (less than 5 percent) had on/off air bag
`switches. For 88 vehicles checked for status of this on/off switch, 51 vehicles had the switch
`“on” and 37 had the switch “off.” Sixteen children were in the front passenger seat with an
`activated (“on”) air bag switch; 2 of these children were in a rear-facing CRS, 4 were in a
`forward-facing seat, 3 were in a SB, and 7 were unrestrained.
`
`RECOMMENDATIONS
`
`
`Periodic monitoring of CRS misuse among the general public is recommended because of
`continuous upgrades and design changes to vehicle occupant protection systems and CRS models
`(e.g., LATCH systems, side air bags); frequent changes (strengthening) of occupant protection
`laws in States; and a perpetual supply of new parents responsible for protecting child passengers
`in vehicles. CRS misuse observations with the general public should be made by qualified and
`experienced personnel who are trained to gather CRS misuse data. Train-the-trainer workshops
`for supervisors, field managers and senior field observers prepare staff for field observations. At
`least two full days should be spent training field observers.
`
`Continued enforcement of CPS laws is recommended, and there is general public
`
`acceptance for the enforcement of these laws. Programs need to be developed to make law
`enforcement agencies aware of the importance of correct CRS use, as well as keeping children in
`CRSs for as long as possible. Enforcement strategies need to be developed to identify booster
`seat law violations. Law enforcement should also continue to take an active role in community-
`based CRS education programs.
`
`Education programs should continue to promote proper use of CRSs, enforcement of
`
`laws, availability of CRS inspection stations, loaner programs, and local and National CRS
`hotline information assistance. Programs should also provide information about LATCH
`systems and correct usage of the LATCH system.
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`4
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`1.0 INTRODUCTION
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`This chapter presents background information on the purpose of this study;
`characteristics of child restraint systems (CRSs); observational studies of CRS use and misuse;
`injuries associated with types of CRS misuse; and field observation techniques.
`
`BACKGROUND
`
`1.1
`
`The number of young child passengers in vehicles who are either improperly placed in
`
`child restraint systems (CRSs) or moved into adult vehicle safety belts (SBs) prematurely is at an
`alarmingly high rate (Spurlock, Kidd, Mays, McCool, Buckner, Clatos, Rochussen, and Leach,
`1998; Taft, Mickalide, and Taft, 1999; Kohn, Chausmer, and Flood 2000; and Morris, Arbogast,
`Durbin, and Winston 2000). In the mid-1990s, a National CRS misuse study involving random
`observation checks of the public found 79.5 percent CRS misuse (Decina and Knoebel, 1997).
`Current CRS fitting station studies, which involve more of a pre-selected sample of volunteer
`and safety conscious parents/guardians, report over 90 percent misuse (NHTSA, 2001).
`
`Current research also focuses on the injury patterns associated with types of CRS misuse,
`
`especially the premature graduation of children to either booster seats or SBs. In general, these
`studies (Kelleher-Walsh, Walsh, and Duffy, 1995; National Transportation Safety Board, 1996;
`Winston, Durbin, Kallan, and Moll, 2000; and Morris, Arbogast, Durbin, and Winston, 2000)
`have shown that head and facial injuries are predominant regardless of impact point or seat
`position. There is also a high risk of abdominal injury associated with improper booster seat use
`or premature graduation to a SB. For children restrained in CRSs, there is a high frequency of
`shoulder injuries related to harness misuse. In addition, spinal cord injuries result from infants
`being placed in the forward direction in a CRS. As expected, there is also a significantly
`increased likelihood (3 times) of serious injury among unrestrained children who are involved in
`a crash.
`
`Federal, State, and local governments, as well as health care providers and community
`
`safety outreach programs (e.g., SafeKids Coalitions) have made a tireless effort to educate the
`public on proper CRS use. National and State campaigns, as well as local programs
`incorporating child safety seat inspection stations, are in progress. However, CRSs and vehicle
`restraint systems can be complicated. Dozens of CRS makes/models exist. A different CRS
`may be needed for each early life stage. Many CRSs cannot fit securely in certain vehicle seats;
`nor can certain vehicle safety belts tighten enough to properly secure CRSs to the vehicle seat.
`In addition, CRS technology continues to evolve (e.g., LATCH system). To complicate this
`issue even more, there is always a continuous stream of new parents/guardians who need to be
`educated on each type of CRS (i.e., infant, convertible, and booster); and there are some
`economic constraints.
`
`To address these concerns, it is important for NHTSA to periodically monitor the status
`
`of CRS misuse in the Nation. This study sought to focus specifically on CRS misuse measures
`that have the most practical consequence in terms of the risk of injury to a child when involved
`in a motor vehicle crash.
`
`
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`5
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`Characteristics of Child Restraint Systems (CRSs)
`
`Child restraint system designs vary according to the size of the child they are designed to
`restrain, the direction the child should face, the type of internal restraining system, and the
`method of installation. CRSs are designed for coupling the CRS securely to the vehicle seat
`using the vehicle safety belt (SB) or LATCH (lower anchors and tethers for children) system if
`available; and properly securing the child in the CRS with a separate harness and/or other
`restraining surface. Securing these two links between the vehicle and the child is critical in
`reducing injuries or death to a child in the event of a vehicle crash (Weber, 2000).
`
`There are five basic types of CRSs in current use; infant seats, convertible seats (converts
`from rear-facing to forward-facing), forward-facing only seats, booster seats, and integrated
`(built-in) seats. Other less common CRSs are also in use, including the Laptop car seat for
`children of booster-seat weight; car beds for newborns and other very small infants; harness vests
`for toddlers and older children; and restraint systems for children with special needs.
`Characteristics of these CRSs are described below.
`
`The infant seat is primarily designed for children birth to 20 lb. Some infant seats have
`upper weight limits that range from 17 to 22 lb. Infant seats are recommended until the child is
`at least 1 year old and at least 20 lb. Infant seats are typically one-piece, protective molded
`shells. They are designed for a rear-facing installation only. The seat comes equipped with snap-
`in pads and slots for the vehicle safety belts (lap or lap portion of lap/shoulder belt). The infant
`is secured in the CRS with a harness, and, in some cases, a harness retainer (chest) clip to hold
`the shoulder harness together for correct pre-crash positioning. Infant seats include two to three
`sets of slots in the back of the seat to allow for harness adjustment to accommodate an increase
`in the infant’s size. Harness slots should be at or below shoulder level. These seats have either a
`three-point harness that consists of two straps over the shoulder connecting in a “V” shape at the
`buckle or to a small hip pad that attaches to the buckle, or a five-point harness that also has straps
`coming around the hip. The angle of these seats should never be more than 45 degrees from the
`vertical position. The seats can be anchored in place with a vehicle safety belt or LATCH
`attachments. Rear-facing child restraints are not required to have top tethers (Weber, 2000;
`NHTSA, 2001; Stewart and Kern, 2003).
`
`The convertible seat is designed for children from birth to 40 lb. The seat incorporates
`features to allow use for infants as well as toddlers. In the rear-facing position, it is used until
`the child is at least 1 year old and at least 20 lb. Some convertible seats are approved for rear-
`facing use up to 30 or 35 lb. For infants, the top of the child’s head should be well contained
`within the seat’s shell (no less than one inch from the top of the shell). The purpose of the
`harness system in rear-facing seats is to keep the infant’s body, neck, and head contained within
`the shell. For infants, the harness slots should be at or below shoulder level (Weber, 2000; and
`NHTSA, 2001).
`
`In the forward-facing position, the convertible seat carries the child until 40 lb and
`approximately 3 to 4 years of age. Convertible seats have either a five-point harness, three-point
`harness with T-shield combination, or a three-point harness with tray shield combination. The
`five-point harness system has straps that secure at both shoulders, across the upper thighs, and
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`between the legs. It can be adjusted to fit a variety of toddlers snugly and correctly. Harness/T-
`shield combinations secure two shoulder harness straps to a “T”- shaped shield or to a broader
`padded tray positioned in front of the torso and hips. The harness/tray shield combination has a
`crotch strap for the tray shield. It may be separate or be integrated with the shield. Convertible
`seat harness systems can be adjusted as the child grows. There are harness slots that
`accommodate changing the harness straps from the lowest slot position for an infant to the upper
`slots for toddlers. Most of the harness systems require a harness retainer (chest) clip, placed at
`the armpit level of the child. The clip is used as a pre-crash positioner holding the harness straps
`together for correct positioning in the event of a crash (Weber, 2000; and NHTSA, 2001).
`
`Convertible seats also have a reclining mechanism, allowing an infant to sleep at an
`acceptable reclining angle (not more than 45 degrees) while facing the rear, and a toddler to sit
`more upright while facing forward. This seat is anchored in place with a vehicle safety belt or
`LATCH attachments (Weber, 2000 and NHTSA, 2001).
`
`The forward-facing only seats are used for children weighing between 20 and 40 lb; and
`usually at least 1 to 4 years of age. Some models can be used for children up to 60 and 70 lb;
`especially those used as interchangeable booster seats. This would accommodate children
`through approximately 7 years of age. The harness systems are either five-point harnesses or
`overhead shield restraints. For these seats, the height of the shoulder strap is usually above the
`child’s shoulders to effectively limit head excursion, and the height of the seat back should be
`above the child’s ear to protect against rearward bending. Some models require a harness
`retainer (chest) clip, placed at the armpit level of the child to hold the straps in place. The seat is
`anchored in place with a vehicle’s safety belt or LATCH attachments. Models after 1999 are
`equipped with top tether straps to be anchored rearward from the seat. A combination child
`seat/booster used with an internal harness is also manufactured. It is used with an internal
`harness for child securement with children up to 70 lb. Some of these models can have the
`internal harnesses removed and thus the seat can be transformed into a belt-positioning booster
`(BPB) for children weighing over 40 lb. Combination forward-facing child restraints and BPBs
`must have LATCH attachment systems (Weber, 2000; NHTSA, 2001; Stewart and Kern, 2003).
`
`Children in a minimum recommended weight range of 30 to 40 lb and a maximum
`weight range of 60 to 100 lb should be in a booster seat. This includes most 4 to 8 year olds.
`Booster seats provide the transition from child seats with internal harne