Improvement on traffic noise of arterial road through low walls with the opening

Abstract

Lowering of noise reduction quantity that originates for the low wall installed in the roadway edge for the existence of the opening and degree of the effectiveness as a countermeasure with it were examined, and following results were obtained. 1) The lowering of the noise reduction quantity is proportional to path difference and open width of the wall. In the meantime, it is inversely proportional to the length of the wall. And, it becomes small, as it goes to the center of the wall. Still, the lowering of the noise reduction quantity of the opening is seldom equal to the edge of the wall. 2) Whether it was effective as an adaptation countermeasure to the environmental standard in arterial road was examined. The height of observation point is 1.2m from the ground level in the sidewalk edge. As the result, it is possible that the wall of the 1.3m heights gives 3.3dB noise reduction quantity in edge of the wall and opening of the wall. Then, 5.3dB noise reduction quantity is given from the wall in 3m places. The wall of the length over 20m gives the above?mentioned noise reduction quantity, even if the open width is 6m. The proportion suited to the noise environment standard in all time increases formerly 28%, latter 37%.