How do traffic lights work?

Question

Some people say it's the high beams that rush it. But i think it is the circle's in the line that function it yes? Do high beams works? I think you have to approach the circles slowly to makes the lights turn quick.

Answer 1

There are really only three basic kinds... the "light sensitive" lights are urban myth.

1) Metal sensors in pavement - will respond if a vehicle is in place. Also sometimes made for bicycles.  The sensors can be placed near the intersection where the first sometimes through the third vehicle will stop.  An additional sensor is often added at high volume traffic lights... so if there is a long line of cars the light knows to stay green longer.  Place a sensor at the start of the left turn lane, for example - maybe 12 cars back on average and "ok, there's a vehicle here, I better stay on longer."

2) "Looping" - On a timer.  It is what it is and will not change.

3)  "Activated" -  Push the button (pedestrian or cyclist) and the countdown begins!

Oops, well there is a 4th... a combination of some type or hybrid of the above!

Answer 2

Some do just work on a timer alone, but many also are connected to sensors in the road that detect whether there is a car there or not.  You can actually see the sensors near intersections.  They look like thin wires or lines in a large rectangular shape just beneath the road.

Some traffic lights may detect headlights too but I don't believe that is as common.

Answer 3

I think they just change automatically by themselves.  That is how it is in my town at least.