The contribution of various levels of speeding to fatal and serious road trauma

Abstract

The purpose of this study was to examine the contribution of the different levels of speeding to road trauma by using the speed data derived from the Event Data Recorders (EDRs) of crashed vehicles and recently developed risk curves that relate absolute risk of serious and fatal injury to impact speed. The analysis used 283 ‘bullet’ vehicles from the CASR-EDR database, of which 74 were speeding. Weightings were applied to minimise sampling bias. A model was applied to the EDR data to determine the reduction in impact speed had the speeding vehicles been travelling at the speed limit. The effect of the reduced impacts speed on lowering the probability of fatal and serious injuries (FSIs) was calculated using injury risk curves. Finally, the contribution of speeding to serious and fatal road trauma was estimated by comparing the sum of the probabilities of an FSI with the original travel speeds to the sum of the probabilities of FSI when speeding was eliminated. Speeding contributes to 18% of fatal and serious road trauma. That is, if speeding were eliminated completely, FSIs would be expected to be reduced by 18%. The results suggest that low level speeding is not benign and should remain the focus of various road safety interventions, along with all levels of speeding.