This document summarizes the acoustic properties and pavement performance of three asphalt quieter pavement projects. Each of the projects included open graded friction course pavement built with sections of crumb rubber and polymer modified asphalt binders. Performance was compared to control sections of HMA (Hot Mix Asphalt) Class 1/2 inch.
The open graded friction course sections were audibly quieter than the control section between one and fourteen months after construction. The rutting/wear on the open graded friction course sections was higher than the control section. On two of the projects the rutting/wear exceeded the depth of the overlay and reached a level that would require early replacement of the pavement.
The increases in noise and rutting/wear occurred primarily during the time periods when studded tires are legal in the state and studded tires are believed to be the primary cause of these increases.
Based on the results of the research, WSDOT has concluded that open graded friction course pavements are not a viable option as a noise mitigation strategy for the State of Washington.