Mashayekh, Y. and Hendrickson, C. (2013)
Green Streets, Highways, and Development 2013. Reston: ASCE, 2013. pp. 202-211.
Some insight into the benefits of regularly and frequently maintaining traffic signal timing within and across jurisdictional boundaries is provided. The rapidly growing Cranberry Township located at the crossroad of two interstate highways (Pennsylvania Turnpike [I-76] and I-79) in the state of Pennsylvania, 20 miles north of Pittsburgh is used as a case study. Environmental and economic costs due to the absence of monitoring and updating traffic signal timing are estimated. While traffic signal timing optimization and coordination is a cost effective strategy to reduce travel time and its consequential air emissions along corridors, implementing such timing plans is only effective at and around the time of implementation, while travel demand remains constant. As times passes, with the fluctuation of vehicular demands, especially in rapidly developing areas, timing plans need to be monitored and modified. In Cranberry Township such developments and travel demand fluctuations result in significant increase in costs of travel (time and fuel) and external environmental costs. Estimates show that timing plans that were at their optimal level at the time of implementation, if left unmodified, result in an 18% increase in the cost of fuel, a 13% increase in the cost of travel time, and an 11% increase in the external environmental costs in less than two years.