SCOOT and Incidents: Performance Evaluation in Simulated Environment

Abstract

SCOOT is a widely used adaptive signal control system. There have been many evaluations of SCOOT during normal traffic conditions. It is hypothesized that SCOOT's ability to adapt to varying traffic during incidents provides an added benefit over its normal congestion-relieving capability. Through an interface between CORSIM and an actual SCOOT system, this study evaluates, in a simulated environment, SCOOT's performance during incidents to quantify these additional benefits. The evaluation is made over a range of volumes and incident durations. A theoretical test network and two real-world networks are simulated. Network and intersection delay, travel time, and queue length are used as measures of effectiveness (MOEs) throughout the comparison to quantify total and marginal benefits. During a 45-min incident within the Salt Lake City downtown area network, SCOOT reduced network delay, travel time, intersection delay, and queue length by 28.3%, 22.8%, 30.7 %, and 24.2 %, respectively, relative to the optimized plan-based control. Similar results were observed on the other real-world network. Although adaptive control has benefits above plan-based signal control, the findings indicate that during incidents, SCOOT provides an additional increase in benefits. The findings indicate that average SCOOT MOEs improve by 7% for a 15-min incident, by 12% for a 30-min incident, and by 18% for a 45-min incident depending on congestion level. The additional benefits that SCOOT adaptive control provides during incidents are quantified through the system's inherent ability to respond to traffic conditions in real time.