Bad vibrations for truck drivers
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• Vibrations that would impair the efficiency of a driver after only a short time have been discovered by Motor Industry Research Association engineers during the evaluation of a proposed ISO standard on vehicle ride measurement. The work was being done for incorporation in a BSI draft for development entitled Guide for the Evaluation of Human Exposure to Whole-body Vibration.
This is revealed in MIRA's annual report, covering the period July 1 1971 to June 30 1972. It records that much use has been made of the Mark 2 ride meters, in some cases by members and in other cases by MIRA — the latter tests being concerned with the riding qualities of commercial vehicles and public service vehicles.
A substantial contract has been obtained by MIRA for investigating the ride qualities of military ambulances and the Association has been looking for sponsors for corresponding work on civil ambulances.
Noise and ride are prominent among research being undertaken by MIRA. For example, the standard test procedure for measuring combustion and mechanical noise of engines has reached its third draft, while DoE-sponsored work in the development of a quiet commercial vehicle has included measurement of external and internal vehicle noise; facilities for investigating exhaust and cooling-system noise have been built for this project, while the Association has developed a compact portable instrument to assess the effect of vehicle modifications on internal noise.
Commercial vehicle cab noise is one of the elements in a noise study designed to establish people's subjective response to different noise levels and frequencies inside vehicles. Early results suggest that increase or reduction in level at either end of the noise "spectrum" separately has little effect, but simultaneous increase or decrease of the high and low frequency levels has a much more pronounced effect on observers.
Seating, ride, ventilation and general comfort on long-distance motorway coaches have also been studied and a report has been published; among the recommendations are that the maximum noise level during second-gear acceleration should not exceed 77dBA for long-distance vehicles or 81dBA for other kinds of service.
The isolation of features of vehicle noise which disturb driver comfort is among the general research projects in MIRA's 1972-73 programme.
Lorry park chain
• Nineteen sites have been identified for acquisition and development as lorry parks in the national chain, Mr John Peyton told the Commons.