Road traffic noise prediction model "ASJ RTN-Model 2013" proposed by the Acoustical Society of Japan - Part 2: Study on sound emission of road vehicles

The Acoustical Society of Japan (ASJ) has published a new revised version of road traffic noise prediction method “ASJ RTN-Model 2013”, in which the calculation formulas for the A-weighted sound power level of each type of road vehicle are specified. The sound power level is given simply as a function of the running speed in consideration of practicality and convenience. The several calculation formulas in this model had been developed using the measured data in 1991–1998. Since 2009, the Research Committee in ASJ has been accumulating new data about noise emission of road vehicles. In this study, the A-weighted sound power levels measured during the 1990’s were compared with those in recent years. In addition, during the last decade, hybrid and electric vehicles are becoming popular and the number of production is rapidly increasing. The noise reduction effect of these low-emission vehicles was examined. As a result, it has been found that there are not any remarkable differences between the sound power levels measured in the 1990's and those in recent years, and the noise reduction effect of low-emission vehicles could be applied to the noise prediction in the vicinity of signalized intersections or expressway tollgates.