ROAD SURFACE DESCRIPTION IN RELATION TO VEHICLE RESPONSE

Single-profile description of a road surface as a random process is a well established basis for vehicle response analysis and presents no great difficulty. More realistic response analysis calls for the description of the profiles of near-side and off-side tracks or, as a means to this end, description of the actual road surface, as such. Adoption of the hypothesis isotropy, together with a single road profile description, permits a whole surface to be described simply. A particular profile description can then be made the basis of an isotropic model from which the required track cross-spectra can be derived for any track width. Coherency functions obtained from this model are compared with those obtained from road measurements and it is concluded that the model is valid where (as is often the case) an approximation is acceptable. (a) (TRRL)