Contribution of alternative road surfaces to noise abatement

Abstract

The increase of noise due to traffic particularly in urban areas has led road administrations to look for low noise surfaces in order to reduce noise impact and to improve environmental quality. This paper aims at assessing the effect of alternative road surfaces on noise abatement. It presents the main results obtained with two distinct experiments, originally intended for other purposes, which address a significant number of non conventional road surfaces. These experiments included nine road surfaces: three of them were gap graded, three contained rubberized asphalt, one had porous asphalt and two had dense asphalt. On these road sections the tyre-road noise generated by two-axle heavy trucks and three-axle heavy trucks and several light vehicles at three levels of speed were measured by means of pass-by tests. Surface texture tests were also performed. The results focused on: i) noise level variation versus speed; ii) estimated noise level for each speed level versus type of surface; iii) the variation of estimated noise level with regards to a reference surface. The best performances were achieved by gap graded mixtures with and without rubberized binder and small grain sizes. The fair behaviour shown by the porous asphalt indicates that the surface texture determined by the grain size seems to influence the noise level more than porosity. Further research on tyre-surface noise should include wide ranges of testing speeds for heavy vehicles, tests with the surface wet, tests that can provide texture spectrum and sound absorption tests.