New research in noise reduction and safety

Abstract

Paper presented at the 30th Annual Southern African Transport Conference 11-14 July 2011 "Africa on the Move", CSIR International Convention Centre, Pretoria, South Africa.

Noise is defined as a loud sound of any sort that is disagreeable or unwanted. Throughout the ages of civilized history, noise has been an annoying irritant to mankind. In recent years the noise level of freeways in urban and suburban areas in the United States has increased perceptibly as freeway traffic has increased and more people are living closer to freeways. To reduce such a noisy irritant generated by traffic on concrete or asphalt pavements Arizona has employed either a 12.5 or 25 mm asphalt-rubber open graded friction course hot mix surfacing. This paper reviews the experience and research in Arizona and California with using asphalt-rubber open graded friction course pavements to reduce the noise by 3-12 decibels. These findings have led to Arizona developing a large scale program of covering over 2000 lane kilometers of concrete pavement with a 25 mm asphalt-rubber open graded friction hot mix surface course to substantially reduce noise. This program started in 2002 and is referred to in Arizona as the Quiet Pavements Program and has been very successful. In addition Texas has noted an improvement in safety due to the use of open graded permeable surface courses.