Abstract: Vehicles running on bridges under crosswind are susceptible to safety issues. The wind field characteristics above traffic lanes within a certain height are available by means of the section model wind tunnel tests. Based on the equivalent method of the aerodynamic forces and moments for road vehicles, both the equivalent wind velocity and scale factor are adopted to investigate the effects of the flow around bridge deck on the aerodynamic forces of road vehicles. The dimensionless rolling and sideslip safety factors are introduced to evaluate the vehicle safety on the basis of the coupling vibration of wind-vehicle-bridge system. It investigates the effects of wind velocity and vehicle speed on the safety of different types of vehicles. Results indicate that the level of safety of vehicles decreases with the increase of wind velocity and vehicle speed; the safety of articulated lorry and coaches are reduced considering the equivalent aerodynamic effects of wind field above bridge decks. The maximum relative error of the RSF and SSF for articulated lorry reaches up to 28.0% and 184.3%, respectively.