Measuring Benefits of Adaptive Traffic Signal Control: Case Study of Mill Plain Boulevard, Vancouver, Washington

The City of Vancouver, Washington implemented an adaptive control system for traffic signal operations at 12 intersections along Mill Plain Blvd. Performance measurement of this system was the main objective of this research. Link, intersection, and travel-time data were compiled and statistically analyzed. Data observed from travel-time runs (collected via a “floating car”) and data collected from system detectors were used to compare performance of the system in the control case (time of day signal control) and the treatment case (adaptive signal control). This research showed that adaptive traffic signal control generally has a positive impact on the system; however, differences could be observed based on the direction of traffic and volume thresholds. Based on the operational studies, average speed improved up to 25%, the travel time decreased up to 20% and number of stops decreased up to 44% under adaptive control in the eastbound direction. Westbound traffic, however, was impacted…negatively!