Noise control at congested urban intersections: Sensitivity analysis of traffic management alternatives

Urban areas of Beirut suffer severe traffic congestion because of a deficie nt transportation system resulting in economic losses and adverse environme ntal impacts. Grade-separations are proposed at several intersections to al leviate or minimize this problem. Noise levels, which are highly dependent on the geometric configuration of an intersection, are a major environmenta l concern, This paper presents an impact assessment of traffic noise at urb an intersections including an analysis of traffic management strategies. No ise measurements were taken at several intersections to describe existing n oise exposure levels and to calibrate a noise attenuation model. Simulation s were performed for several traffic management scenarios including with an d without grade separations, changes in vehicle mix, type of pavement, and level-of-service. Two typical intersections with 65 and 95 percent traffic through a grade separation are analyzed. An assessment of impact significan ce associated with traffic noise emissions was then conducted by comparing predicted noise exposure levels with baseline noise levels and relevant noi se exposure standards, with the objective of optimizing intersection manage ment in terms of minimal noise impacts. Simulation results showed that besi des traffic flow improvement, a grade separation reduces noise impacts beca use of its ability to deviate sound waves from sensitive receptors, However , the traffic management alternatives considered in this study do not appea r to produce a difference that would be discernable to neighborhood residen ts and, hence, would not be effective, by themselves, in controlling urban noise. (C) 2000 Institute of Noise Control Engineering.