Question:  I’m designing a traffic signal at an intersection with a heavy right turn out of a minor street, plus a very low volume pedestrian crossing that is in conflict with the right turn move.  I’m thinking of having a right turn arrow that will display a red when there are pedestrians, and will show a green when there are no pedestrians.  The controller is a 170 with McCain software.  Here’s a sketch of what I’m wanting to do, how do I make it work? 

 

Answer:  McCain software has a feature called Pedestrian Omit.  If you hook the wiring for the Phase 7 right turn to an overlap output instead of a phase output, you can program that overlap with a Phase 4 pedestrian omit.  That way it will display green with Phase 4 when there are no Phase 4P calls, but will stay red where there are.