Description
The Arizona Department of Transportation recognized a need to provide the citizens of Maricopa County living next to its freeways with a less noisy quieter freeway. The Maricopa County freeway system is referred to as the MAG freeway system and it is composed of over 1200 lane miles (2000 lane kilometers) of multi-lane concrete pavement. Noise is defined as a loud sound of any sort that is disagreeable or unwanted and the people living next to the MAG freeway highways complained that the freeways were too noisy. 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 and the MAG freeway system in particular 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 a 25 mm open graded friction course asphalt-rubber hot mix surface course. This paper reviews the experience in Arizona and research in California as well, 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 1200 lane miles (2000 lane kilometers) of relatively new and new concrete with a 25 mm (1 in.) asphalt-rubber open graded friction hot mix surface course to substantially reduce noise. This program is referred to in Arizona as the Quiet Pavements Program and has been very successful.
