Prediction of road traffic noise using two-dimensional numerical analysis

Abstract

For acoustically complicated road structures such as semi-underground roads and special areas in which a viaduct road and a flat road with noise barriers exist together, prediction of road traffic noise is complicated because of multiple reflections and diffractions that occur inside the road structures. For such road structures, an energy-based engineering model cannot be applied and noise propagation should be addressed through introduction of wave theory. When the road structures have almost identical cross-sectional shape along the road, two-dimensional (2-D) wave-based numerical analyses are applicable. In the prediction model of road traffic noise, the ASJ-RTN Model 2003, published by the Acoustical Society of Japan (ASJ), the application of 2D wave-based numerical analysis was introduced as a prediction method for such complicated road structures. Comparisons between calculations by BEM and FDM and field measurements and experiments for three actual road structures were conducted. Consequently, calculation results agreed well with measured ones. Therefore, the validity of the calculation methods was confirmed. This research was discussed in the Research Committee of Road Traffic Noise in ASJ. Measurement data were provided by Nippon Expressway Company and the Nagoya Expressway Public Corporation.