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How Signal Timing Works

PRIORITYwave requests the next phase — the traffic controller in the cabinet still decides when it's safe to grant it. 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​

The controller never cuts a safety interval short — 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.

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.