Two car frontal collisions: the role of car mass, collision speed distribution and frontal stiffness in occupant fatality and injury

There is controversy regarding the role of car mass in injury and fatality risk in individual car-to-car collisions and for overall car populations. In addition the effect of frontal stiffness on both the case and the partner cars is disputed, and the role of the distribution of collision closing speed has not been adequately examined. In this paper empirical car crash characteristics derived from onboard crash recorders are combined with risk functions based on mean vehicle acceleration. The model predictions closely match the available real life data for frontal collisions for the US (fatalities), Japan and Germany (AIS3+). The model is used to predict the roles of case car mass, collision closing speed distributions and frontal stiffness in relative vehicle safety. Results show that increasing the 50th percentile car mass from 1200kg to 1600kg reduces the AIS3+ injury to drivers by 4%, while decreasing the 50th percentile car mass from 1200kg to 800kg increases overall risk by 15%. By comparison, reducing the 99.99thpercentile collision speed from 200km/h to 150km/h reduces injury risk by14%, but reducing the 50th percentile collision speed from 60 km/h to 50km/h reduces injury risk by 31%. Finally a car population with the structural characteristics of the 'soft' 50th percentile reduces injury risk by 23%.For the covering abstract see E134311.