On-Board Sound Intensity (OBSI) Evaluation of Quiet Pavements Utilized in New Jersey

Quiet pavements have received much attention throughout the transportation related noise community, as a method of reducing highway related noise. This has spurred an interest to determine the noise related properties of current surface materials and surface modification techniques for asphalt and concrete pavement surfaces. Two methods, the close-proximity-method (CPX) and the on-board-sound-intensity method (OBSI), have gained success as practical methods of measuring sound properties of the tire/pavement interface, which is the largest contributing factor to highway noise from passenger vehicles moving over 30 mph (48.3 kph). In New Jersey, concern over noise mitigation techniques and the exorbitant cost of implementing sound barriers has been steadily on the rise. The New Jersey Department of Transportation (NJDOT) became interested in noise mitigation via research completed by the Center for Advanced Infrastructure and Transportation (CAIT) and the National Center for Asphalt Technology (NCAT) utilizing the CPX method in 2005. The resultant research effort provided the NJDOT with valuable information allowing them to more appropriately select asphalt overlays that were not just durable and rut resistant, but also quieter. In 2010, a research effort was initiated with the OBSI method (AASHTO TP76, Method of Tire/Pavement Noise Using the On-Board Sound Intensity Method) to measure new and old in-service pavements found in New Jersey. Data presented in this paper represent the OBSI noise measurements of typical pavement surfaces found in New Jersey. Attempts are also made to compare and evaluate the differences in noise and mixture properties of polymer modified and asphalt rubber Open Graded Friction Course mixes.