Quantifying CRS Fit in the Vehicle Seat Environment: Dimensional Comparison Approach

Co-Principal Investigator: Amanda Agnew, PhD, The Ohio State University; Julie Bing, MS, The Ohio State University

Below is an executive summary of this project. Please note that this summary describes results and interpretation that may not be final. Final interpretation of results will be in the peer-reviewed literature.

Current estimates of the prevalence of misuse of child restraint systems (CRS) are as high as 94 percent, which can lead to an increased risk of injury or death for child occupants. Although the majority of CRS misuse is attributed to consumer installation errors, physical incompatibilities between CRS and vehicle models may also cause or exacerbate problems in the installation process. While all CRS on the U.S. market comply with the federal standard for dynamic testing requirements under FMVSS 213, it remains unclear which child restraint features are the best fit for certain vehicle environments.

This study aimed to collect quantitative and descriptive data on a large set of CRS and vehicles currently on the road, to identify factors that influence compatibility between CRS and vehicles, and to use this information to provide benchmark data for CRS/vehicle manufacturers and consumers. Detailed dimensional data were collected from 59 CRS, which included 31 rear-facing (RF) and 28 forward-facing (FF) seats. The researchers collected 37 data points (including outer dimensions, information about the belt path, recline angle, top tether, and type of LATCH hooks) from each CRS. In addition, they documented the dimensions and features of the second-row seats of 61 vehicles representing 27 different manufacturers, with 76 data points collected for each vehicle, as well as the space available in the seat, the contours of the seat pan and seat back, the locations of seat belt and LATCH anchors, and clearance space relative to the front row of seats and vehicle ceiling.

Several of the dimensions measured on each CRS are shown above.

Following data collection, key dimensions were compared in order to identify the following most frequent points of incompatibility:

  • Seat pan angle for RF CRS: 42 percent of RF CRS cannot naturally sit within the required angle range on vehicle seats.
  • Width of CRS compared to width of vehicle seat: 37 percent of CRS do not fit between the vehicle seat’s side bolsters and require the CRS base to sit on top of the side bolsters.
  • Height of seat back for FF CRS: 34 percent of FF CRS have interference with the vehicle’s head restraint in their seat position.
  • Clearance space behind front row seats for RF CRS: 27 percent of RF CRS cannot fit comfortably behind the front row vehicle seats.

There are many implications for the use of these data. The information will be made available for CRS and vehicle manufacturers to use as a benchmark for design decisions. For a more immediate impact, the results of this study can also be used in educational materials to guide caregivers in choosing a CRS for their vehicle. These data provide an important resource to help improve the CRS installation process, to lower the rate of CRS misuse, and, ultimately, to reduce the rate of child injury and death when motor vehicle crashes occur.

Project Team Member

John H. Bolte IV, PhD, The Ohio State University


Colleen Mismas, The Ohio State University; Kevin Soong, The Ohio State University

IAB Mentors

Ron Burton, Transportation Research Center Inc.; Audrey Eagle, Chrysler Group LLC; Keith Nagelski, Britax Child Safety, Inc.; Eric Dahle, Evenflo Company Inc.; Doug Longhitano, American Honda Motor Co., Inc.; Julie Kleinert, General Motors Holdings LLC