Harm Causation and Ranking in Car Crashes

This paper addresses the crash protection of occupants of the car fleet in transition from the late 1970's to the early 1980's. Three files of the National Highway Traffic Safety Administration are used: the NASS 1979 to 1983, the PARS 1979 to 1983, and the NCSS 1977 to 1979. Fatalities, injured survivors by severity, and all accident involved car occupants are addressed. Risks of crash and injury outcomes are determined and analyzed as a function of risk influencing factors, especially factors that may vary significantly during the time period under consideration. Ejection risks and ejection patterns are addressed explicitly. Harm, an earlier introduced human casualty integrator, and harm distributions are extensively examined and updated with respect to earlier results. Harm and harm pattern changes, whether statistical fluctuations or systematic variations, are analyzed. The principal conclusions of this study are: The very significant reduction of car occupant casualties that took place in the early 1980's is concurrent with an equally significant reduction of accident involved car occupants. However, casualty risks per involved occupant remain remarkably constant during this period. There are indications that the car fleet crashworthiness improved significantly, on a crash-severity-specific basis, but the benefits of this improvement may have been denied by a shift of crash severities towards higher values. However, no major shifts are evident in harm distribution patterns. With minor exceptions, sources of injury and injured body regions retain the rankings assigned to them in an earlier study on the basis of harm and harm reduction potential.