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A group within the International Organization for Standardization has worked out a standard for a road surface intended to be used during vehicle noise measurements according to the ISO 362 and 7188 procedures. The surface should be equally suited for use in similar measuring procedures where full-throttle operation of vehicles is needed and where the influence of the surface on noise emission and propagation must be kept at a minimum. Several test tracks have been laid according to the proposed specifications. A Round Robin Test has been conducted in which five cars and one truck were run on a number of test tracks in Europe and Japan. The results show that the surface meets the basic requirements of giving low tire/road noise while still having negligible sound absorption characteristics. Also, the site-to-site variability is low. In this paper, the convener of the working group presents the work and a preliminary proposal.

During the latest decades tirelroad noise has been recognized as one of the most significant parts of road traffic noise. It has therefore become necessary to employ suitable noise reduction measures on tires as well as road surfaces which do not impose safety problems. Since many of these measures rely on appropriate measuring methods, several activities in order to standardize such methods for tirelroad noise have started. The paper begins with a systematic analysis of the rather complicated tirelroad noise problem and suggests ways to solve it. Then a review is presented of the major measuring methods considered for standardization with regard to classification of tires: The coast-by method The trailer method The laboratory drum method The trailer coast-by method The advantages and disadvantages as well as which applications are the most suitable for each one are discussed. Particular attention is paid to the extremely important question of test track surface selection.