Sound Pressure and Intensity Evaluations OF Low Noise Pavements Structures with Open-Graded Asphalt Mixtures.

摘要

Five different low noise pavements were constructed and evaluated at the NCAT test track. Both single and double layer structures constructed with fine and coarse open-graded mixtures were tested. Macrotexture measurements of the paved surfaces were done using the circular texture meter (CTM) and the ultra-light inertial profiler (ULIP). Sound measurements on the sections were taken using sound pressure and sound intensity microphones. Sound pressure and intensity was evaluated using the NCAT close proximity (CPX) acoustic trailer at speeds of 45 and 60 mph. Sound intensity was also measured using three different passenger vehicles. The weight of two of the passenger vehicles was increased by 200 lbs to investigate this influence on noise at the pavement-tire interface. Practical problems with the bracket used for sound intensity measurements restricted testing with the passenger vehicles to 45 mph. Three different tire types were evaluated including the new standard reference test tire. Sound intensity testing of the low noise sections was also done using one of NCAT’s triple trailer trucks. The sound absorption characteristics of the open-graded asphalt mixtures were evaluated using the impedance tube in the field. The sound measurement results indicated that each of the low noise sections evaluated had excellent noise attenuation characteristics. The double layer structures with fine open-graded surfacing were the best performing of those tested.