A computational study of the aerodynamic forces acting on a tractor-trailer vehicle on a bridge in cross-wind

This paper examines the effect of truck speed on the aerodynamic forces acting on a standard sized, North American transport truck travelling across a bridge under conditions of cross-wind. The objective is to establish a relationship between wind speed, truck speed and propensity for truck rollover that may be used to devise strategies for accident avoidance. Conditions of a moving truck travelling in both windward and leeward lanes were considered with a cross-wind speed of 120 km/h and truck speeds of 0–120 km/h. Using the calculated pressure distributions on the surface of the truck; the aerodynamic lift, drag and moment coefficients were determined for relative wind directions. The results show that the aerodynamic moment tending to overturn a truck in the windward lane of the bridge rises from approximately 120 kN m at low speeds (0–40 km/h) to 217 kN m at a truck speed of 120 km/h. For a truck in the leeward lane, the corresponding moments are substantially less, at 82 and 154 kN m, respectively. The 1.1 m barrier wall along the side of the bridge is a contributing factor to the aerodynamic difference between windward and leeward lanes.