Fyrhjulsmodeller för bestämning av vägojämnhet: dokumentation av verksamhet på VTI 2002-–2011

Peter Andrén

In Sweden, longitudinal roughness has been more or less synonymous with the International Roughness Index (IRI). IRI is calculated from a longitudinal profile, and describes the accumulated movement between the wheel and chassis on a quarter-car model. The result is given as this movement divided with the traveled length. In Sweden, the unit millimeters per mere is normally used. The IRI-model is only affected by movements in the vertical direction, and the speed is fixed to 80 km/h. This report presents the work to make a full-car model, with the aim to produce a more realistic view of the movements of a vehicle traveling on a normal road. The benefits with a more realistic vehicle model is that indices with a higher correlation to drivers’ and passengers’ experiences can be made. It should be mentioned that a relatively high correlation between IRI and drivers’ estimates road condition has been shown. A FullCar model should, however, give more detailed information about the effect of the road surface on the vehicle. A truck model could, for example, be used to find sections with a dangerous cross fall. A realistic vehicle model could also be used in studies concerning the deterioration of roads, as the road is partly worn by wheel abrasions and partly deformed by contact forces. A simple model could simulate hundreds of thousands of vehicle passages in only a few minutes.



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