To predict the level of ground vibration in the vicinity of a busy roadway, dynamic vehicle models are required from which tyre forces can be calculated for a given road-surface profile. A method has been devised by which a single model of a multi-axle vehicle can be used to represent all vehicles on the road. The model accounts for variation in vehicle mass, speed and wheelbase; it relies on the assumption that all vehicles have similar characteristic frequencies and damping ratios. The effect of wheelbase filtering, where a given combination of axle spacing and vehicle speed "tunes in" to road roughness of certain wavelengths, is found to be unimportant for calculations of traffic-induced ground vibration because vehicle speeds and wheelbase lengths are sufficiently varied among vehicles on a busy road. In this paper methods of vehicle modelling appropriate for the inclusion of some statistical variation between vehicles are described, while in an accompanying paper [1] its application to the calculation of ground-vibration power spectra is discussed. © 1991.
