Traffic Congestion and its Impacts on Greenhouse Gas Emissions: Can ITS Help?

Transportation plays a significant role in greenhouse gas emissions, accounting for approximately a third of the United States’ CO2 inventory. In order to reduce CO2 emissions in the future, transportation policy makers are looking to make vehicles more efficient and increasing the use of carbon-neutral alternative fuels. In addition, CO2 emissions can be lowered by improving traffic operations, specifically through the reduction of traffic congestion. This research examines traffic congestion and its impact on CO2 emissions using detailed energy and emission models and linking them to real-world driving patterns and traffic conditions. It has been found that CO2 emissions can be reduced through three different strategies: 1) reducing severe congestion, allowing traffic to flow at higher speeds; 2) reducing excessively high freeflow speeds to more moderate conditions; and 3) eliminating the acceleration/deceleration events associated with stop-and-go traffic that exists during congested conditions. Details on several CE-CERT research projects that directly address these strategies will be provided.