Grade separations for traffic congestion relief: Air quality and noise implications

Traffic congestion at major intersections is typically an accumulation of the effects of several factors, including short-sighted urban planning and ineffective enforcement of traffic regulations. This paper evaluates air quality and noise implications at a typical intersection where a grade separation is proposed to relief traffic congestion. For this purpose, traffic counts, air quality characterization, and noise level measurements were conducted to define existing conditions. Mathematical simulations were performed to evaluate the future evolution of the site with and without a grade separation. Potential impacts are evaluated by comparing simulated exposure levels of air quality and noise indicators with relevant environmental standards. Mitigation measures in the context of constructing grade separations in urban areas are also outlined.