The vibrations induced by train passages and propagated through the soil may affect neighbouring buildings. In order to predict vibrations near railway lines, dynamic axle-loads based on the vehicle-track-soil interaction were calculated from the dynamic stiffness of the vehicle and the track-soil system. Time consuming simulations have been used to establish an approximate model to describe such vehicle-track-soil interactions that yields transfer functions between the various geometric or stiffness irregularities and the axle loads of the train. Besides geometric irregularities of the vehicle wheels and the track also geometric irregularities of the trackbed were considered. The random stiffness variation due to variations in the ballast and the subsoil and the regular stiffness variation due to the rail support on sleepers have also been transferred to effective track irregularities.
All relevant transfer functions for the prediction of axle-load spectra are presented graphically and as general formula covering different vehicle and track parameters. The prediction method was applied to a ballast track and a slab track and compared with corresponding axle-box measurements. Additionally, ground vibration measurements at numerous sites were exploited for the axle-load spectra and the validation of the prediction method. Experimental data and theory-based calculations revealed sound estimates for dynamic axle-load spectra and their relation to train speed, track stiffness and vehicle-track resonance.