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

Abstract

Heavy goods vehicles apply higher than expected loads to road pavements because of vehicle bouncing brought on by road roughness. The Transport Research Laboratory (TRL) has measured these loads for a variety of steel, rubber and air suspensions, on the TRL research track and on public highways. The 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. Peak dynamic wheel load measurements on bridges have revealed that road–friendly suspensions are, generally, also bridge friendly. 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 work also includes an examination of the appropriateness of definitions currently used for road–friendliness, such as the EC definition, based exclusively on the suspension's sprung mass resonant 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.