Parametric sensitivity analysis of noise impact of multihighways in urban areas

Traffic noise along highways varies with the projected growth in future traffic use, particularly near developing urban areas, and the conditions of the tire–road surfacing interface. When traffic demand increases and those interface conditions deteriorate, highway noise impacts become significant and mitigation strategies required. This paper presents a leading application of the US Federal Highway Administration (FHWA)—a newly released Traffic Noise Model (TNM)— which is now being phased in by the FHWA to replace the old STAMINA/OPTIMA package. An uncommon application of TNM to evaluate the noise impact of multihighways running parallel and above each other is examined in the context of a developing city with limited building regulations and inadequate setback distances between the edge of roadways and building lines. For this purpose, traffic flow characteristics, including volume, vehicular classification, and travel speeds, were defined along existing and proposed highways. Sensitive noise receptors were identified and noise measurements were taken during peak traffic periods. Field measurements were used to calibrate the FHWA-TNM. Model simulations were then conducted to predict future noise exposure levels, evaluate the effect of noise barriers, and assess the model sensitivity to parameter variation.