Reducing Carbon Emissions and Congestion by Coordinating Traffic Signals

Poorly timed traffic signals lead to start-and-stop activity and low travel speeds, which greatly impacts carbon emissions. This article summarizes current traffic signal operations in the United States and discusses the potential to coordinate traffic signals to reduce congestion and carbon emissions. Investment in signal timing is lacking because agencies must prioritize limited budgets with competing construction, maintenance and operations needs. However, this lack of investment has led to an overall poor performance for traffic signal operations in the United States. The first step in traffic signal coordination is to develop a master plan that considers the needs for signal timing, agency resources, communication systems and priority corridors. Then new coordinated signals timings on corridors should be developed, implemented and fine-tuned on a regional basis. An ongoing program should be developed to make sure the coordinated signal timings are maintained and updated at least every 5 years, and an ongoing maintenance program should be developed to quickly repair vehicle detection devices and maintain efficient traffic signal operations. The cost to implement new signal timing is approximately $3,500 per intersection, but could reduce fuel consumption up to 10% and reduce harmful emissions up to 22%.