Abstract
This report describes a cooperative programme sponsored by TRRL which has produced heavy diesel engined articulated vehicles having considerably lower external and internal noise levels than vehicles in current operation. The other organisations involved were Fodens limited, Rolls Royce motors limited, Leyland vehicles, MIRA, ISVR and NEL, and the work was aimed at reducing the noise levels from the engine, exhaust and cooling systems and tyre-road surface interaction. Results are given from a number of experimental vehicle builds and a demonstration vehicle built to production standards, which emitted no more than 80 db(a), is described. (Author/publisher)