Originally Posted by
genec
There is also a new type of sensor... I watched the whole evolution take place on one of my neighborhood streets. This is a camera sensor and it apparently looks for some object that appears in the field of view and has a certain contrast before it changes.
On this particular street, I could never get the loop to trigger... and later the engineers told me that the loop was bad and could not be adjusted, so they replaced it with a video sensor.
Now I find that if I approach right in the center of the lane, the light triggers just moments after I get to the stop line. If I arrive in the dark and don't have lights... no trigger. If I wear dark clothing, no trigger. But with that in mind, I know how to trigger the thing and now dress and light accordingly.
The video sensor is the trickiest one to trip. I can trip them at night because I can either shine my helmet light on them or the notice my lights. During the daylight, the cameras are specifically calibrated to ignore narrow targets like pedestrians. Often cyclists fall into this category. I've found that if I stand at the light waving my arms like an idiot I can trip the light about 50% of the time.
Of course, if the light doesn't trip, I treat it as a malfunctioning light and proceed...with caution.