The increase of the maximum axle load limit in South Africasparked renewed interest into methods of quantifying traffic loadassociated damage on pavements. Extensive research with the HeavyVehicle Simulator (HVS) over the past 20 years has led to improvedfundamental understanding of pavement performance and has permittedthe development of Equivalent Damage Factors (EDFs) for single-axleloads. A major limitation of this approach is that it does notdirectly facilitate the calculation of EDFs for multiple axlecontigurations, i.e. tandem or tridem axles.

This paper describes a method for extending the existing HVS-basedmethod to the determination of EDFs for multiple axle configurations.This, in principle, facilitates the development of guidelineson permissible axle loads and tyre inflation pressures for differentaxle configurations. The method assesses the effects of: wheelload, contact stress, single and dual wheels, and single, tandemand tridem axle configurations. The method, therefore, enablesdetermination of EDFs for the accurate estimation of equivalenttraffic loading for design purposes and performance analysis enhancinglife predictions and management decisions.

Initial determinations indicated the advantage to road friendlinessof grouping axles together into tandem or tridem configurations.Additionally, the use of dual-wheel instead of single-wheel axlescould result in the axle load being increased by up to 30 percentwithout any increase in pavement damage.