This paper describes influence of cargo lorry traveling at high speed under a lightweight footbridge on the structure vibrations. The unsteady CFD simulations were performed to obtain aerodynamic load functions on the footbridge. These loads were introduced to nonlinear structural dynamics transient calculation to obtain footbridge response. The influence of aerodynamic forces was evaluated in terms of pedestrian comfort and safety. Parametric study of the influence of vehicle speed, structure clearance, cabin deflectors and distance between lorries grouped in convoy is also presented.