Refining GreenSTEP: Impacts of Vehicle Technologies and ITS/Operational Improvements on Travel Speed and Fuel Consumption Curves

Kelly Clifton, Portland State University



This report describes analysis undertaken to establish a method for incorporating traffic operations and ITS strategies into the GreenSTEP model. We first discuss operations impacts on fuel economy and delay from the literature. Then, an investigation of delay adjustments in GreenSTEP shows that different methods of representing delay changes lead to similar (and small) impacts on fuel economy. From this result we establish average speed adjustment by congestion level as the preferred method for incorporating delay effects from operations improvements. An investigation of aggregate traffic operations impacts produces estimates of base speeds without operations improvements, maximum speeds with full operational improvements, and existing deployments by city size for each congestion level. These estimates are made for ramp metering, incident management, traffic signal coordination, and access management strategies. Additionally, a comparison of constant-speed and drive schedule-based fuel-speed curves generates estimates of potential fuel benefits from eco-driving and speed-smoothing traffic management strategies. Results show that the cumulative impact of delay-based operations strategies on fuel economy is small, though speed-smoothing effects can be large. The operations impacts estimates are used to provide guidance for estimates of operations efficacy in delay reductions and speed smoothing for the GreenSTEP model. The proposed implementation strategy includes an efficacy estimates tool for the net effects of operations strategies, and identifies locations in the model where those effects can be included. Traffic operations impacts on travel demand are separately applied as travel demand management inputs to the existing GreenSTEP model.

Project Details

Project Type:
Project Status:
End Date:
September 30,2012
UTC Grant Cycle:
non-UTC project