Generation of ground vibrations by road vehicles crossing traffic calming humps and cushions

Road humps and speed cushions is a simple method of reducing the severity and number of road accidents as a result of decrease in speeds at which drivers choose to travel However, the experimental investigations carried out by the Transport Research Laboratory (TRL) have demonstrated that such a gain is achieved partly in expense of the increased traffic noise and ground-borne vibration (Watts 1997). It has been shown during these investigations that speed control cushions and road humps can produce perceptible levels of ground vibration which depend on vehicle type and hump and cushion design. Theoretical investigations of ground vibrations generated by road traffic have been carried out by several authors. A number of works has been done for vehicles travelling on statistically rough surfaces of rather good quality (Taniguchi et al. 1979, Le Houedec et al 1982, Hunt 1991, Hanazato et al. 1991) and for accelerating and braking vehicles (Krylov 1995a-c, 1996a,b). However, vibrations caused by vehicles travelling over single obstacles were analysed only very briefly (Krylov 1995a,c) and no calculations directly relevant to traffic calming road humps and speed cushions were carried out. In the present paper, ground vibrations generated by vehicles travelling on roads with installed humps of different shapes and sizes are investigated in more detail on the basis of the earlier developed general approach (Krylov 1995a,c). The results are compared with the recent experiments carried out by the TRL.