SKID-RESISTANT ROAD SURFACINGS AND TYRE NOISE.

Coarse texture is incorporated into the surface of roads primarily to disperse water rapidly and it is essential if skidding-resistance is to be maintained at high speeds. Unfortunately, deep texture brings with it the penalty of tyre noise and so compromise values have to be sought. In order to quantify the problem, measurements have been made on a range of textured roads both of high- and low-speed braking force coefficient and of peak vehicle noise level adjacent to the road. Results showed, predictably, that noise increases with increasing texture but, less predictably, that different relationships exist for bituminous and grooved concrete surfacings. Earlier work had shown that the effectiveness of a given level of texture in maintaining high-speed skid-resistance also differs for the two forms of surfacing and by combining these two effects it can now be shown that a unique linear relationship exists between the tyre noise emanating from a surfacing and the effectiveness of its texture for high-speed skid-resistance. This finding enables a policy on texture requirements to be formulated which is equitable to both bituminous and concrete interests and which attempts to strike a balance between road safety and noise.(a) /TRRL/