The Development of Seat Belts and an Evaluation of the Efficacy of Some Current Designs

Front seat, rear seat, lap only and combination lap/shoulder belt restraints are analyzed for their effectiveness in injury mitigation. The question arises, have seat belt designs satisfactorily progressed over the years and can the performance of some current design features be improved? This paper reviews the history of seat belt development and the performance of some current design features. Specific interest is paid to 1) type 1 lap belt performance as seen in most rear seats and, 2) the current shoulder harness tension eliminator, window shade/comfort feature, in U.S. domestic automobiles, This paper reviews some case examples where seat belt design and performance in these areas can be significantly improved. Installation requirements of rear seat shoulder belts have recently been addressed by NHTSA. The tension-eliminator or window shade/comfort feature introduces slack into the system. The effect of slack on the performance of a lap/ shoulder belt system is examined