Analysing the Influence of Encroachment Angle and Median Parameters on Safety of Rural Highways Using Vehicle Dynamics Performance

Cross median crashes are among the most dangerous types of highway crashes, especially for trucks, which should be more considered by highway engineers. Skidding and roll-over are the important factors which affect trucks' cross median crashes. In this research, the median safety is evaluated through TruckSim dynamic simulation and violations of running off from the median; also, statistical analyses are carried out. The results of this research show that encroachment angle is the most effective parameter for skidding and roll-over. The side friction factor increases as the speed increases, which means that more side friction demand is produced for trucks at high speeds. From the viewpoint of rolling, the most critical situation is found at 25 degrees of encroachment and 0.8 m shoulder width. It can be seen that the unpaved shoulder is more critical than paved shoulder and two-way slope cross-sections are more important than the one-way slope. The result of this paper could be used for designing safer roadways.