Interactions of Rear-Facing Child Restraints in Frontal Crash Tests

The aims of this study were to investigate the kinematics of child anthropomorphic test devices in a large sample of rear-facing child restraint system installations and the effects of anti-rebound features and load legs on the kinematics of rear-facing child anthropomorphic test devices. The test matrix included a general sample of 70 rear-facing child restraint system installations to observe trends in frontal crash tests; 14 full-scale crash tests with paired comparisons to investigate the effect of anti-rebound features; and five paired comparisons of rear-facing child restraint systems installed with and without a load leg. The paired t-test was used to determine the statistical significance of differences in kinematic responses. In the general sample, 84% of anthropomorphic test devices in infant seats with the base in outboard seats interacted with the first-row seat. In 52% of tests, the anthropomorphic test device head directly contacted the front seatback. Head accelerations 80 g were caused by interactions between: the child restraint system and front seatback; the anthropomorphic test device head and the interior surface of the child restraint system; or the anthropomorphic test device head and front seatback. In the anti-rebound sample, head contact on rebound occurred in three infant seat installations, and all were associated with head resultant accelerations ≤33 g. The mean paired difference in head 3 ms clip was negligible (p 0.05). In the load leg sample, the load leg limited forward excursion and forward rotation of the rear-facing child restraint system, thereby contributing to the containment of the anthropomorphic test device within the boundary of the child restraint system shell. In this study, anti-rebound features did not improve the kinematics of pediatric anthropomorphic test devices. The feasibility of including the use of the load leg in the Canadian regulatory test protocol should be explored.