Dynamic Pavement Loads and Tests of Road-Friendliness for Heavy Vehicle Suspensions

Heavy goods vehicles apply higher than expected loads to road pavements because of dynamic bouncing. TRL has measured these loads for a variety of steel, rubber and air suspensions on the TRL research track and on public highways. Bouncing of goods vehicles causes dynamic pavement loads with standard deviations that are typically 10-30% of static loads, depending on the suspension type and road roughness. Tests show how much these dynamic loads can be reduced by suitable choice of suspension. An estimate is made of the amount that road wear could be reduced if all goods vehicles used the best of current suspensions. Some measurements have been made of the effect of different suspensions on the peak dynamic axle loads on bridges.

Work is in progress to develop simple instrumentation that can be fitted quickly to vehicles for measuring dynamic wheel loads, and test procedures to enable the road-friendliness of different types of suspension to be assessed. The European Communities have defined road-friendliness in terms of suspension frequency and damping. Experimental evidence linking dynamic loads on roads to the parametric characteristics of suspensions is described. Other potential procedures for rating suspensions are discussed.