Specifications

Vehicle Actuation (VA)
On VA, if there are no approaching vehicles, the signals will revert to red in both directions. The
first vehicle to arrive will register a demand for the signals to change on that approach. See ‘Nudge
circuit’ on page 14.
Following vehicles will extend the time that the green light is shown. The duration of the green will
vary between the minimum green period (7 or 12 seconds) and the maximum green period (settable
on the controller). The signals will change either when the last vehicle has passed, or after the
maximum time the green signal has been set for.
How does it work?
Each signal is provided with a vehicle-detector unit. These units normally use microwave technology
and are often referred to as an ‘MVD’ (Microwave Vehicle Detector). Other technology can be used,
but the unit must be approved (see page 3).
The MVD can detect most moving motor vehicles, including larger motorcycles, up to 40 metres
away, but with smaller motorcycles and cycles the distance is 25 metres — provided they are
travelling towards the MVD at speeds greater than 10 mph and the detector is correctly aligned (see
next page). Some detectors may be able to work outside these limits.
An indicator is illuminated when a vehicle is detected and the ‘detect’ message is sent from the MVD
to the controller.
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