Placement of Sound-Absorbing Materials To Control Traffic Noise Reflections at a Highway Underpass

The effectiveness of the installation of sound-absorbing material on the vertical retaining walls of a highway underpass was evaluated. A multifaceted experimental approach, involving both the actual traffic noise source and an artificial source, was used. The experimental results indicated that only a minor reduction in noise levels had been achieved from the sound-absorbing material. A theoretical analysis of sound propagation near highway underpasses was made and implemented in a computer simulation model. The application of the model to the highway underpass supported the experimental results. In addition, the modeling results indicated that reflections from the bridge understructure were more significant than reflections from the vertical walls.