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How Signal Timing Works

PRIORITYwave requests the next phase — the traffic controller in the cabinet still runs the sequence, and at most intersections it decides when it's safe to move on. Understanding that relationship is the single most useful thing to know before running an intersection, because it explains almost every "I pressed the button and nothing happened" moment.

Learn the Intersection First​

Every intersection is programmed differently. Before actively controlling a new one, stand back and watch a few full cycles:

  • Which movements go first, and which directions move together.
  • How pedestrian walk, flashing hand, and countdown timing runs.
  • Whether there are protected turns or movements that run on their own.
  • Roughly how long each movement lasts.
important

Two intersections that look identical can be programmed completely differently. Assume nothing at a new location.

Why a Press Doesn't Always Move the Signal Immediately​

Most controllers keep their safety timing in manual control: pedestrian clearances, yellows, and red clearances run their full programmed length, no matter who's asking. So when you send an advance:

  • If a pedestrian countdown is running, the controller finishes it first. The vehicle signal may sit on green while a flashing hand completes, even though your command was accepted.
  • At many intersections, a press during a green or walk phase starts the pedestrian clearance, and it takes a second accepted advance afterward to move the signal through yellow and red to the next movement.
  • Protected turns and other special intervals run their programmed course before the next phase gets its green.

None of this is a fault — it's the controller doing exactly what it's designed to do. Watch the signal after every command, and if nothing moves, let the active interval finish before sending another.

Not every cabinet enforces that timing in manual control, though. On those, an advance that arrives too soon can cut the yellow or red clearance short — so PRIORITYwave holds off new advances for its Advance Cooldown after each one. Set it at or above the longest yellow plus red clearance at the intersections you work.

Emergency Vehicle & Train Preemption​

If the intersection has emergency vehicle preemption, a responding vehicle can take priority over manual control. The controller serves the preemption event automatically, then returns to manual operation when it ends. If you are operating on an intersection that has a railroad crossing, trains may also activate preemption events. Once the train passes, the intersection should return to manual control.