Field Evaluation of Acoustical Performance of Parallel Highway Noise Barriersalong Route 99 in Sacramento, California

摘要

The effects of multiple reflections between two parallel highway noise barrierson the acoustical performance of each of the barriers have been a subject of considerable controversy. Mathematical and scale modeling predict possible large reductions (degradations) in the effectiveness of noise barriers with smooth, hard surfaces (such as masonry or concrete) due to parallel configurations. However, noise measurements under conditions of actual highway traffic, typical barrier heights and separations have yet to confirm the large degradations. The report presents the methods and results of a parallel noise barrier research project performed by the California Department of Transportation (Caltrans). Field measurements of noise, traffic, and meteorology were made in three stages: before barrier construction, after construction of the near barrier, and after construction of the barrier on the opposite side of a highway. The selected site was typical of many parallel barrier configurations in California.