Rear Seat Occupant Protection in Frontal Crashes

Though a significant body of literature exists on the safety performance and effectiveness of various types of front seat occupant restraint systems, there is a paucity of data on the performance of rear seat occupant restraint systems. A research program was initiated to better understand rear seat restraint performance. Research included examining real world data using National Automotive Sampling System/Crashworthiness Data System (NASS/CDS) and Fatality Analysis Reporting System (FARS) as well as conducting full frontal vehicle crashes into rigid barriers with dummies restrained in rear seats. Child dummies (Hybrid III 6 year-old) and adult dummies (Hybrid III 5th percentile female and 50th percentile male) were used for this purpose. The dummies were placed in rear outboard seats with lap/shoulder belts as well as in the center seating position where the lap/shoulder belts were integrated to the seat. A double-paired comparison study using FARS data files suggested that while occupants younger than 50 years of age benefit from sitting in rear seats in frontal crashes, restrained adult occupants older than 50 years are significantly better off in the front seats than the rear seats. The most injured body region for restrained children in rear seats is the head while that for restrained adults is the thorax. The major injury source for restrained occupants, not in child safety seats, is the seat belts while that for unrestrained occupants is the front seat back. The injury measures of restrained adult dummies in rear seats in frontal crash tests were generally higher than those of dummies of the same size in the driver and front passenger seat. The seat backs of integrated rear seats experienced excessive forward rotation in frontal crash tests, thereby causing the dummy’s head to hit the console or front seatback, resulting in high head and neck injury measures. The field and vehicle crash test data indicate that rear seat restraints could be further optimized to mitigate injury in frontal crashes for older rear seat occupants.