Analysis of the factors affecting the severity of two-vehicle crashes

AbstractThis study performs a comprehensive analysis of the effect of different environmental, demographic and vehicle variables on the severity of two-vehicle crashes. The limitations associated with previous studies have been addressed by using a large crash database, properly defining the independent variables, using an appropriate statistical model, and by considering the effect of factors normally unaccounted for such as crash type, DUI involvement, impact speed and height incompatibilities between the two vehicles. The use of a multinomial logit model provides the flexibility to evaluate variables that have opposing effects at different injury levels (such as airbag availability). An innovative linear crash cost model is also used to estimate the effect of the independent variables in terms of dollars. This simplification is particularly useful when discussing potential policy treatments for improving road safety with transportation officials, politicians and other decision makers. The findings from the two models are consistent and suggest that the type of crash has a great impact on severity. Age is the most significant demographic variable, with children being least likely to be injured, and older occupants being most likely to be injured. Occupant behavior also seems to be critical, as the use of seatbelts, and alcohol involvement, greatly decrease or increase, respectively, the severity of the crash. Heavier vehicles increase the safety of its occupants but decrease the safety of occupants of the other vehicle. Vehicle types are not found to be as significant as weight, with the notable exception of pickups, which are at the same time more crashworthy and more aggressive than passenger cars.