What is the use of a sensor on the top of a traffic signal? whether it takes image of the car?

Question

What is the use of a sensor on the top of a traffic signal? whether it takes image of the car?

Answer 1

It's a sensor that is actuated by a strobe light on top of emergency vehicles to stop traffic at an intersection.

Answer 2

well if its a camera then its to catch people running a red light if its a sensor there are different meanings. it could be for detecting cars at the light so it can change from red to green and change with the flow of traffic or it could be to pick up the flashing lights and opticon system of emergency vehicles, that way it turns green and they can proceed through!

Answer 3

those are for police and fire trucks to be able to change the signal so they don't have to stop

Answer 4

so emergency vehicles can change the light

on youtube.com theres some video that show that you can do it, i really dont think it will work but i want to try it some day