Road Profile Statistics Relevant for Vehicle Fatigue

Klas Bogsjö

Abstract:: Road profiles are studied from a vehicle fatigue point of view. A wide range of roads have been measured: from smooth motorways to very rough gravel roads. It is observed that the road profiles consist of irregular sections, which makes the stationary Gaussian model unsuitable (Paper A). In Paper B, a method for automatic identification of such irregularities is presented. It is verified that the irregular sections cause the major part of the fatigue damage induced in vehicles. Based on this result, a new single track model is proposed, which includes randomly shaped and located irregularities. In Paper C, an evaluation method of single track models is proposed. This evaluation method is extended to models of parallel tracks in Paper D. A new `parallel tracks' model is proposed and evaluated accordingly. In Paper E, the coherence between the parallel road tracks is studied. A simple one-parametric model is proposed for the coherence. In Paper F a new theoretical method to compute the expected vehicle fatigue damage caused by road irregularities is presented.

Key words:: Road profiles, road roughness, vehicle fatigue, stochastic processes, model evaluation