TRAFFIC CALMING AND ASSOCIATED GROUND VIBRATIONS

Abstract

Experimental studies by the Transport Research Laboratory (TRL) show that road humps and speed cushions can increase the noise and ground-borne vibration from vehicles passing over them. This paper investigates in more detail the ground vibrations generated by vehicles travelling on roads with humps of different shapes and sizes. A vehicle is modelled as a mechanical system, interacting with the ground surface and having four degrees of freedom, associated with its main low-frequency resonances. Analytical expressions for the generated ground vibration spectra are obtained by solving the dynamic equations and the elastic equation describing ground motion, with appropriate boundary conditions on the ground surface. It is shown that the amplitudes and spectra of the generated ground vibrations depend on the shapes and sizes of the humps, on vehicle speeds and loads, and on ground elastic properties. The level of vibration is roughly proportional to the ratio of hump height to hump length, decreases the smoother the hump, and tends to be maximum at a specific vehicle velocity. The results are compared with those of recent TRL experiments, and a good agreement between theoretical and empirical results is found, so that the theoretical model can be applied successfully in practice. For the covering abstract, see IRRD E100715.