Do sound walls and noise barriers reduce road noise?
Not always. When a noise barrier wall is constructed, there is a significant noise drop immediately behind the wall. The problem is that those buildings that are on hillsides, at intersections or driveways or anywhere there is an opening in the wall, will not benefit from noise reduction. In some cases where noise walls are built parallel to one another, noise reflections or echoes of the sound waves off the opposite wall can actually increase noise levels at a location near the highway.
