18. The expert from the Netherlands introduced GRB-60-04 and Add.1 in which he pointed out that, under urban driving conditions, the rolling noise dominates the overall noise production and is influenced by the properties of the road surface (like surface texture, acoustical absorption and air‐pumping). Thus, improving the surface properties would result in a lower rolling noise level. According to the expert, quiet road surfaces are a valuable measure to reduce traffic noise, either on their own or in combination with other noise reducing strategies, and generally demonstrate a positive cost/benefit ratio.

19. The Chair stressed the importance of the tyre-road interaction for sound emissions and noted that, for the time being, GRB has no mandate for regulating road surfaces. GRB agreed to resume this discussion at its next session and looked forward to new studies and presentations on the issue.