Smarter Traffic Signal Timing Using Connected Vehicle Data Can Cut Intersection Delays by 53 Seconds Per Vehicle and Reduce Missed Green Lights by 30 Percent.
Screening Methodology Applied to Signalized Intersections in Indiana Identified Locations for Potential Timing Improvements.
Indiana, United States
Business Processes to Prioritize Traffic Signal Retiming and Assess the Impact of Retiming Activities
Summary Information
State DOTs manage thousands of traffic signals, and evaluating the performance of each one individually to identify system-wide improvement opportunities can be a challenging and resource-intensive task. This study described how a scalable screening methodology based on Connected vehicle (CV) trajectory data could systematically evaluate performance at the movement level to prioritize retiming and maintenance activities. To demonstrate the proposed methodology, 11 timing changes were implemented at nine signalized intersections across Indiana over various time-of-day (TOD) periods in 2024. A detailed before-and-after analysis was conducted for each modified intersection that presented overall positive changes.
METHODOLOGY
The methodology proposed in this study identifies specific intersection movements where signal timing changes could reduce split failures (SF). A split failure occurs when a vehicle, based on its connected vehicle (CV) trajectory data, stops two or more times before crossing an intersection — typically indicating it missed a green light and had to wait through multiple cycles.
The first step is to identify the movement with the highest rate of split failures. This is designated as the critical movement, and it becomes the primary target for receiving additional green time (i.e., split). Next, the analysis evaluates potential donor movements — phases with sufficient available green time that can be reallocated to the critical movement without negatively impacting their own performance.
Data collected two weeks prior and two weeks after the timing changes were used to evaluate impacts. The analysis focused on three key performance measures for each movement: the percentage of split failures, the percentage of arrivals on green (AOG), and the weighted average control delay.
FINDINGS
The use case evaluated at the intersection of US-421 and W 116th Street showed that SF reductions were accomplished for the two critical signal phases with no negative impact to donor phases. Specifically, the proposed method led to a 30 and nine percent reductions in SF, a 15 and eight percent increase in AOG, and a 53 and 19 sec/veh reduction in delay for the two benefited target (critical) phases, respectively.
