Temporary roadwork traffic lights

[175gt]

Does anyone know how far along the road the sensors on temporary traffic lights look?

Roadworks on an A-road on my way to work, luckily soon after I join the road, so I'm usually near the front of the queue. Anyway, watching cars going through got me thinking. Seems that more and more people now move across to the other lane to go through the roadworks well in advance of the traffic light, whereas I tend to stay on the left until much closer. I keep thinking that if everyone moves over really early, then it'll appear to the sensor that there's no traffic queuing and it'll change back to red.

Is this likely to make any difference or do the sensors look far enough down the road for it not to matter?

[Kevin VRs]

It depends entirely on who set it up, and how. I have seen them pointing into the hedge on occasions.

[littleredrooster]

AFAIK, the sensor is only used to detect the stationary traffic. Once triggered, the lights then controlled by a timer. If neither sensor detects traffic, both lights are set to red until a car arrives.

A cold car is often invisible to the sensor, as it detects heat.

[durbster]

littleredrooster said:

A cold car is often invisible to the sensor, as it detects heat.

Interesting. I wonder how much heat an electric car generates in comparison?

[175gt]

littleredrooster said:

AFAIK, the sensor is only used to detect the stationary traffic. Once triggered, the lights then controlled by a timer.

Yeah, this seems to make sense. Guess I can banish slight twinges of guilt from now on then and join everyone else moving out early!

[TheLurker]

I got told that they sense movement, and work up to 200-300m away. The lights aren't always set up to use the sensors though. The best way to make them change for you is to wave your arm out the window at them.