Some remarks on the prediction of road traffic induced ground-borne vibrations

In urban areas road traffic induced vibrations are rising some problems since they are often considered to be responsible for minor damages and for nuisance in building close to major road sections. The approach of the problem appears extremely complex since different expertises are involved. On a methodological point of view the study of the problem can be tackled by separately analysing the three main phases in which the phenomenon can be split: the generation phase due to the dynamic interaction between the heavy vehicle and the road profile, the propagation phase through the pavements and the underlying soils, the reception phase in the buildings nearby. In this paper, following an extensive research that has been carried out on this subject, vibration generation and propagation models derived from literature are reviewed and major advantages and drawbacks of the different modelling approaches are highlighted. Furthermore, a new 3-D model for the prediction of traffic induced ground borne vibration is proposed. The model is based on a hybrid numerical-FEM procedure and allows the evaluation of the vibration level in the time and frequency domain at an arbitrary distance from the road axis caused by a moving heavy vehicle. Input parameters are kinematical, mechanical and inertial properties of the vehicle, road profile and layout, mechanical properties of the pavement and soil materials. The model has been experimentally validated through a comparison with field data reported in literature. In addition, an application of the model to the traffic calming design is presented. Results from numerical simulations showed that a optimized sinusoidal road hump profile may induce lower vibration level if compared with that provided by a conventional trapezoidal shaped one currently adopted in Italy.