Abstract
Situations arise in which noise barriers are overlapped to accommodate highway entrance or exit ramps, service roads, local access roadways, underground utilities, or community desires regarding placement within the right-of-way. This arrangement of two parallel vertical barriers with an opening in between gives rise to the overlap noise barrier problem. The need to protect residential or institutional properties near the barrier opening led to the development of an analytical procedure to investigate the reflection-diffraction effects of overlapping barrier designs.