Optimizing the rear seat environment for older children, adults, and infants

Our recent rear seat safety research found that more-forward and higher lap belt anchorage locations and much shorter and stiffer seat cushions can improve the protection of older children from 6 to 12 years old who are using the vehicle belt without a booster. The objective of this study was to investigate whether the optimal rear seat restraint systems for adults and infants are consistent with those for older children.

We conducted sensitivity analyses and design optimizations for adults and for infants in a rear-facing child restraint system (CRS) using a set of MADYMO models, an automated simulation framework, and occupant belt-fit and posture prediction models from our previous studies. A series of 12 sled tests was also used to validate the computational models.

The optimal belt anchorage locations and the seat cushion length for older children, adults, and rear-facing CRS-seated infants conflict with each other. In particular, more-forward lap belt anchorage locations that prevent submarining for older children would reduce the protection to both adults and CRS-seated infants, although the protection is still acceptable based on regulated injury criteria. A shorter seat cushion could provide optimal protection to older children and adults but would significantly increase the CRS rotation.

The findings of this study suggested that adaptive/adjustable restraint systems are necessary to simultaneously improve the rear seat occupant protection for all age groups. Supplemental materials are available for this article. Go to the publisher's online edition of Traffic Injury Prevention to view the supplemental file.