Evaluation of the Influence of Overturning Parameters on Run-Off-the-Road Vehicles in Vertical Curves

This research seeks to solve the problems of vertical curves with a foreslope using a more suitable model than the point mass model. In this regard, investigating the effect of lateral acceleration and yaw and roll moments on safe foreslope in vertical curves on rural highways and the concavity or convexity of vertical curves was defined as the main goal of this research. Finally, by presenting regression modeling, lateral acceleration was modeled as a dependent variable based on vehicle speed, vehicle departure angle, and slope of foreslope as independent variables. It was revealed that a zero longitudinal slope and tangent alignment do not significantly affect the lateral acceleration of passenger cars and cannot be considered a serious threat to their overturning. Also, the departure angle of 10-15 degrees for the truck vehicle causes the vehicle to yaw in place at all speeds. The results of presenting the lateral acceleration model showed that R coefficient for the lateral acceleration model is 0.886, which indicates the appropriate correlation of the model with the data. Also, the results of the model showed that the variables of vehicle speed, departure angle of the vehicle from the road and the slope of the foreslope have a significant impact on the model.