<p>Aerodynamic and dynamic interference from trains is a key issue of concern for the safety of road vehicles travelling on single-level rail-cum road bridges. Based on the wind-road vehicle-train-bridge (WRTB) coupled vibration system developed herein, this study examines the dynamic characteristics when road vehicles meet trains in this situation. The influence of load combination, vehicle type and vehicle location is analyzed. A method to obtain the aerodynamic load of road vehicles encountering the train at an arbitrary wind speed is proposed. The results show that due to the windproof facilities and the large line distance between the railway and highway, the aerodynamic and dynamic influence of trains on road vehicles is slight, and the vibration of road vehicles depends on the road roughness. Among the road vehicles discussed, the bus is the easiest to rollover, and the truck-trailer is the easiest to sideslip. Compared with the aerodynamic impact of trains, the crosswind has a more significant influence on road vehicles. The first peak/valley value of aerodynamic loads determines the maximum dynamic response, and the quick method is optimized based on this conclusion. Test cases show that the optimized method can produce conservative results and can be used for relevant research or engineering applications.</p>