Analysis of Wind as a Contributing Factor in Bus Accidents in Rolling Terrain

Large vehicles including double-decker buses are vulnerable to traffic accidents, especially in rolling terrain. However, causes of these accidents are often obscured by the combined impact of the vehicle, driving behavior, and environmental conditions like wind and terrain. This study tried to evaluate bus safety in rolling terrain and wind gradient. A simulation model of the double-decker bus was established and computational fluid dynamics experiment was conducted to obtain the aerodynamic forces. The vehicle dynamics principle was applied to assess the bus stability, and the limit minimum radii were calculated at different wind velocities and driving speeds. Results show that it is unsafe for double-decker buses to travel at design speeds in rolling sections under gale winds. The study is expected to prompt transport enterprises to set strict speed limits for different road sections. The outcome also provides a design guidance for scenic roads in hilly areas.