A rear seat car passenger who is not restrained by a seat belt or other restraint system can be thrown forward in an accident and kill or injure the restrained driver or passenger ahead of them. A recent analysis of Japanese accident data has estimated that the risk of death to front seat occupants is increased five-fold by the presence of an unrestrained rear seat passenger, and that the increase is even greater in frontal impacts. This report reviews the analysis and concludes that its results are not reliable, principally because of a serious deficiency in the number of fatalities among the data studied. It analyses British casualty data and data from the TRL Seat Belt Survey and concludes that the risk is increased by about three-quarters : it appears that between 8 and 15 front seat occupants die each year in this country as a result of an unrestrained passenger seated behind them. (Author/Publisher)
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