Speed-Space Analysis and Dynamic All-Red Extension for Red-Light Running Protection at Signalized Intersections on Rural High-Speed Arterials

This study used a speed-space analysis to analyze the distribution of red-light runners at intersection approaches during the all-red interval to assess their risk levels. Additionally, various speed-space diagrams were utilized to assess the performance of the Dynamic All-Red Extension (DARE) system and establish system parameters for field implementation. Two signalized intersections in rural Alabama with speeds of over 55 mph were selected for system implementation and data collection. Analysis results revealed that a significant number of red-light runners at these intersections were not protected by typical all-red intervals calculated based only on the Institute of Transportation Engineers (ITE) red-clearance equation. These red-light runners were detected up to 340 ft upstream of the stop line when the signal turned red. Their time to red-light violations extended up to 3.6 s from the onset of the red indication. The results of the speed-space analysis, combined with the distribution of red-light runners' times to red-light violation, indicated that enhanced protection for these vehicles could be achieved by incorporating kth-percentile values of red-light runners' times to red-light violation alongside the red clearance intervals based on the ITE equation. This concept involves safeguarding a certain portion of red-light runners through the red-clearance interval, while the remainder would be protected by DARE. Speed-space analysis also proved to be helpful in determining key parameters for DARE implementation. Overall, the DARE system demonstrated commendable performance in protecting high-risk red-light runners with minimal disruption to traffic operations.