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Old 04-10-2009, 10:00 PM
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The one beside the red light (in the left hand image) is an Opticom traffic signal pre-emption receiver. Emergency vehicles will have strobe lights, sometimes visible light, sometimes infrared, that will be received by these devices, triggering the lights in that direction to go green and everything else to cycle quickly to red. The light will be held green for as long as the strobe is visible - which sometimes causes problems if the truck parks in sight of the intersection and the crew forgets to shut off the Opticom sender. (The sender is supposed to automatically shut down when the park brake is engaged, but not all agencies wire it up this way.)

The box on the other picture could be anything from WiFi to MOTOMESH networking. (MESH network services kind of operate like WiFi does, except that every node in the system can carry traffic for another node, making it more like the Internet as a whole - so if you're out of range of the box on that light pole, but in range of a cop car that is in range of the light pole, you still have coverage.)

On top of the light housing itself is the photocell which detects when the sky is dark enough for the lights to turn on.
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