QUIET PAVEMENTS RAISE THE ROOF IN EUROPE

This article presents observations from an agency-industry scanning tour of five European nations, looking at practices for pavement noise mitigation. The objective of the tour was to examine policies, strategies, and innovative methods of dealing with road noise, how to measure it, the pavement's contribution to it, and what can be done to mitigate the noise. The approach to handling road noise differs between Europe and the U.S. In Europe, the focus is on taking an integrated approach through the use of low-noise pavements, while the U.S. solution has been to use noise barriers. Surface texture and porosity are two of the biggest factors in producing low noise asphalt pavements. With surface texture, the size of the particles on the pavement surface affects the interaction with tires in terms of tread vibration, with larger sized surface texture typically producing greater noise. In addition, a surface that is relatively flat with voids in it (a negative texture) has better acoustical performance than a surface that has protrusions above the surface (a positive texture). Porosity in the surface is the second key factor in achieving further noise reduction. The article also discusses some issues related to porosity, such as clogging, winter maintenance, and skid resistance.