The measurement of relative vehicle occupant injury risk and injury severity is useful for assessing the safety performance of particular vehicle models and for monitoring design improvements in vehicles over time. Internationally, five key measures of vehicle crashworthiness have been developed that attempt to measure the risk of injury or serious injury to a vehicle driver involved in a two-car collision. This paper aims to extend existing theoretical comparisons of the safety measures by examining the relative effectiveness of each measure using simulated crash data with known properties.
A theoretical framework is developed that describes the process of injury data generation in terms of injury risk and injury severity. Application of the safety rating methods to simulated crash data derived from this framework enables quantification of the ability of each rating method to accurately estimate known vehicle safety performance. This is not possible through a theoretical statistical comparison alone. Multiple simulation runs have been conducted to investigate the effects of different relationships between injury risk and impact severity on the effectiveness of the safety rating measures. Results of the analysis highlight the efficiencies, deficiencies and biases of each of the rating methods under various input scenarios.