Embarcadero & T Third Light Rail
Next Generation Transit Signal Priority
To reduce red light delay to trains, Greg was assigned to improve the transit signal priority system along two busy light rail corridors. San Francisco uses an advanced traffic signal software platform, but the transportation department did not have a solid understanding of its features or how they worked. So Greg reverse-engineered the program to fully comprehend its functionality, rewrote its user manual, and trained his colleagues in the art of transit signal optimization. Greg also determined how transit and pedestrian signal timing features could complement rather than conflict with each other. This effort has helped the department improve the performance of transit signal priority citywide.
Greg developed a four-step hierarchy of transit priority, utilizing more aggressive features only when required, in order to maximize transit performance while minimizing unnecessary traffic disruption. The key innovation is the fourth step, a package of conditional traffic signal preempts that interrupt normal signal phasing in order to immediately display the train's green light. Greg convinced the traffic engineers that this complex solution would not impact safety or cause congestion. After a successful pilot location, the hierarchy is now being implemented at all 100 intersections along the two corridors.
