Highway noise

The study considered four basic highway noise reduction constructions: (1) roadside barriers, (2) elevated structures, (3) depressed highway sections, and (4) roadside structures. To minimize the number of variables to be evaluated, strict criteria were imposed on the selection of the test sites. For the roadside barrier, elevated highway, and depressed highway configurations, the result of the evaluation indicate that the design guide procedures tend to underpredict the noise reductions at locations involving small path length differences, and overpredict the noise reductions at locations distant from the roadway when the intervening terrain is free of ground cover.