Effects of Different Vehicle Parameters on Car to Car Frontal Crash Fatality Risk Estimated through a Parameterized Model 2006-01-1134

For the purposes of analyzing and understanding the general effects of a set of different vehicle attributes on overall crash outcome a fleet model is used. It represents the impact response, in a one-dimensional sense, of two vehicle frontal crashes, across the frontal crash velocity spectrum. The parameters studied are vehicle mass, stiffness, intrusion, pulse shape and seatbelt usage. The vehicle impact response parameters are obtained from the NCAP tests. The fatality risk characterization, as a function of the seatbelt use and vehicle velocity, is obtained from the NASS database. The fatality risk is further mapped into average acceleration to allow for evaluation of the different vehicle impact response parameters. The results indicate that the effects of all the parameters are interconnected and none of them is independent. For example, the effect of vehicle mass on fatality risk depends on seatbelt use, vehicle stiffness, available crush, intrusion and pulse shape. As a result of this interaction, the net safety outcome from changes to one of these parameters to reduce fatality risk will depend on the state of the others. For example, vehicle parameter changes, such as increasing stiffness to prevent intrusion, may be beneficial to the belted occupants and counter-indicated for the unbelted; conversely, changes to benefit the unbelted may be counter-indicated for the belted. In general, the effect of changes made to different vehicle attributes intended to improve overall fleet fatality risk will depend on the state of the fleet at the time of the introduction of the changes. Consequently, short-term transitional effects will exist until the changes are complete throughout the fleet, thus rendering a new equilibrium.