Quote:
Originally Posted by some_other_dave
There are lights in my area (SF Bay Area) that are influenced by magnetic loop detectors placed well back of the intersection.
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Same here. Most of the lights on my commute have one loop back away from the intersection and several loops up at the intersection. Generally, they're set up so that the light goes from green to red when a vehicle hasn't passed the advanced loop within a certain amount of time (assuming there's a vehicle at the perpendicular intersection). Typically, the time is about the time it takes someone going slightly lower than "normal" speed to get through the intersection. Some, however, are more or less sensative, i.e., they'll go red with a smaller or larger gap in traffic.
They're one particualr light on my commute that's super sensative--it goes red at the smallest gap in the traffic. I can't tell you how many times I've cursed it out for catching me, but I've learned to do fairly well now by never trusting it (assuming it's going to turn red on me).