Performance Measures for Railroad-Preempted Intersections

The Manual on Uniform Traffic Control Devices provides guidance on when traffic signals should be interconnected with railroad crossings. Various other manuals and reports deal with how the traffic signal preemption logic should be configured. Maintenance practices typically require technicians to perform routine checks to ensure that preemption circuitry is functioning, and agencies often log the preemption events as part of a system-monitoring procedure. However, no procedure or software allows a controller to tabulate performance measures on how effective the preemption logic is at clearing conflicting phases before a train's arrival. This study introduces the concept of using an event-based data collection system to monitor the railroad preemption input, vehicle detectors, and phase indications to develop performance measures for evaluating the effectiveness of clearing movements that cross the tracks before train arrival. These techniques are applied to statistically compare the impact of steerable traffic signal indications at a location where the tracks are within 60 ft of the traffic signal stop bar. Based on a comparison of 700 preemptions before the signal heads were installed with 2,102 preemptions after signal heads were installed, no statistically significant difference was observed.