Why do I observe incorrect traffic-actuated phase operations in conjunction with passage or pulse detectors?
The operational mode of the detector depends on what functionality it supports with regard to actuated control operations. Presence mode should be used when the detector is being used solely to call the phase (e.g., a detector located at or near the stop bar). Passage (pulse) mode detectors are typically used to support green extension and the volume/density operations of the actuated controller (e.g., variable initial and gap reduction functions). When used for these purposes, the passage mode detector is typically located upstream of the stop bar and is primarily used to note the passage of a vehicle (green extension and gap reduction) or to count vehicles (variable initial timing). If a passage mode detector is also being used to call the phase, then the yellow lock function for that phase should be set. With yellow lock set, if any vehicle activates the detector during the yellow or red intervals of the phase, the controller will “remember” that the detector was activated and will
