Driver speed compliance in Western Australia: a multivariate analysis

The importance of identifying factors affecting speeding is related to Police and insurance evidence of speeding as a contributor to road crashes, particularly those involving fatalities and serious injuries. Most of the literature on the causes of speeding regards speeding as a feature of risky driver behaviour or careless driving habits. Some of the literature also refers to the importance of vehicle and road environment features. Studies in Australia and overseas have looked at these factors and their relationship to spot speeds or average speed using bivariate analysis. Few studies have looked at the relative contribution of factors to driver speed compliance. In this study, an ordinary least squares regression procedure estimates that 62% of the variation in vehicle speeds can be explained by variables related to the road environment and vehicles. Moreover, it seems that drivers use posted speed limits as targets rather than delimiters and choose vehicle speeds based on factors other than the desire to be non-compliant. Policymakers intent on improving road safety should redress instances of mismatch between road design and posted speed limits and the possibilities of differential rules for rural/urban, day/night and weekday/weekend driving.