Queensland Department of Main Roads studies have highlighted the importance of two fundamental safety parameters in the relationship between road geometry and vehicle accident rates. These parameters are the 'potential relative speed between vehicles' and the 'decrease in speed between successive geometric elements'. Both are important predictors of accident rates at roundabouts and on steep downgrades. By decreasing the relative speed between vehicles, the rate and severity of multiple vehicle accidents are lowered. A reduction in the decrease in speed between successive geometric elements will produce a similar result for single vehicle accidents. In this paper, these concepts are briefly discussed before considering the likely safety implications on other road design features. Recommendations and examples are then given to minimise the relative speed between vehicles for a number of common situations. Finally, recommendations and examples are given to minimise the decrease in speed between successive elements for a number of common situations. (a) For the covering entry of this conference, please see ITRD abstract no. E202275.
Samenvatting