Use of Both Travel Time and Travel Time Reliability Measures to Quantify Benefits of Signal Timing Maintenance and Optimization

Maintaining and optimizing signal timing contribute directly to an improved end-user driving experience. With recent developments in crowdsourced vehicle probe data, travel time improvements associated with signal retimings can be quantitatively assessed without costly infrastructure. This study considers a three-stage evaluation of signalized corridor performance—(a) using existing controller settings, (b) after synchronization of controller clocks and time-of-day plans, and (c) after offset optimization—for the weekday morning peak, midday, and evening peak periods. The percentage of vehicles arriving on green and the vehicle travel time distributions were evaluated for each of the tasks in each period. The travel time data were then used to quantify user benefits with the mean–variance method to determine the dollar savings for the tasks performed. Signal time-of-day plan maintenance and clock synchronization accounted for some of the travel time benefits, but the savings were less reliable than with progression optimization, which improved both travel times and reliability.