Systemwide Identification of Signal Retiming Opportunities with Connected Vehicle Data to Reduce Split Failures

Abstract

Road networks are significantly affected by traffic signal operations, which contribute from 5% to 10% of all traffic delay in the U.S.A. It is important for agencies to be able to systematically monitor traffic signal performance and have procedures to identify locations as proactively as possible where the redistribution of green time has the greatest potential of reducing congestion. Currently, Automated Traffic Signal Performance Measures (ATSPMs) require extensive communication networks and detectors on all phases at each intersection to effectively monitor the traffic signal performance for every traffic movement. This study utilizes commercially available connected vehicle (CV) trajectory data to identify overcapacity movements where there is availability of unused green time and no downstream blockage by an adjacent signal. Over 100 intersections, 400,000 trajectories, and 6,800,000 Global Positioning System points are evaluated using this method to prioritize signal retiming opportunities in a proposed Relative Performance Diagram (RPD) by assessing split failures and downstream blockage of all traffic movements. Out of the intersections identified as having opportunities for operational improvements, three were selected for retiming. A post-retiming review of the traffic signal performance measures showed up to 30% reductions in split failures, 53 s/veh reductions in control delay, and 21% increase in arrivals on green at the benefited movements. The techniques easily scale to any intersection where CV data is available without the need for vehicle detection or communication technology.

Comparison of Estimated Cycle Split Failures from High-Resolution Controller Event and Connected Vehicle Trajectory Data

“…Accordingly, there has been significant research on calculating signal performance measures and improving intersection efficiency using CV trajectory data [20] [21] [22] [23] [24]. A 2023 study has already used CV trajectory data to identify locations with signal retiming opportunity to reduce SF [5]. The current study employs a similar approach to predict when a split failure has occurred from CV trajectory data.…”

“…A split failure event is when a traffic signal phase fails to serve its entire demand within one cycle, and the performance measure SF refers to the percentage of cycles in a time period which exhibit split failure. The SF value at a signal can be a useful metric to guide appropriate maintenance decisions [5] [6].…”