This report assesses the performance of the TRRL foden quiet heavy vehicle (qhv) during a 2 year period of service with a haulage contractor. An analysis of vehicle operation confirmed that the vehicle was worked normally and gave fuel consumption which was consistent with similar unmodified vehicles. Normal maintenance and servicing was carried out and costed. These costs were increased as a result of the noise quietening features on the vehicle by 1.5 per cent. This increase represents about 0.2 per cent increase in the total operating cost of the vehicle. Apart from the exhaust silencer, the vehicle's noise quietening components have remained in good condition over the trial period. A deterioration in the silencer performance caused the standard test noise levels to increase by between 3.5 and 5 db(a) during the trials. This was caused by a reduction in the hole size in the perforated bridge sections of the silencer by the accumulation of exhaust particles. Steam cleaning the inside of the main gas flow pipe was sufficient to return the silencer to its original noise reduction performance. (Author/publisher)
Abstract