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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.

In September 1984 the European Economic Community agreed a Directive which will require vehicle manufacturers to reduce the drive-by noise of trucks by 3 to 5 decibels by October 1990. The British Government has set up a programme of research and support for development to assist the manufacturers of heavy goods vehicles and their engines to develop products that will comply with the new noise limits and be available for production by 1990. This is called the QHV 90 Programme. QHV 90 includes the development of quiet versions of six goods vehicles of up to 38 tonne weight, and 8 types of diesel engine for commercial vehicles. Reducing the noise from vehicles is to be achieved by quietening the engines, enclosing the engines and improving the effectiveness of the exhaust silencers. Experience with the previous TRRL Quiet Heavy Vehicle between 1971 and 1981 has shown that this is possible at relatively minor cost.