Potential fatality reductions through eliminating occupant ejection from cars

The percent of occupant fatalities preventable by eliminating ejection is calculated using Fatal Accident Reporting System (FARS) data for 1975 through 1986. The calculation requires estimates of two quantities. First, the fraction of all fatally injured occupants who were ejected; this is obtained directly from the FARS data. Second, the probability that an ejected occupant was killed compared to the probability that the occupant would have been killed in a similar crash in the absence of ejection; this quantity is estimated using the double pair comparison method, and its dependence on occupant age and sex and on car mass and model year is examined. High precision estimates of the reduction in fatalities that would result from eliminating ejection as functions of these same variables are thereby obtained. These estimates depend on assuming that whatever method is used to prevent ejection would cause the formerly ejected occupant to acquire the same fatality risk as a nonejected occupant in a similar crash; the study does not address how to prevent ejection. It is concluded that ejection elimination would decrease fatalities to unrestrained car occupants by 18 +/- 1%. The fatality reductions are independent of car seating position (19%, 19%, 17%, 16%, 19%, and 18% for drivers, middle front, right front, left rear, middle rear, and right rear passengers, respectively); they decrease with driver age, from 25% at age 18 years to 7% at 70 years; they decrease with increasing mass, but remained relatively independent of car model year since the early 1970s, being somewhat higher for earlier model years.