How do stoplights work?

Question

I don’t understand how they work, what they’re hooked up to and how they know when to turn from green, to yellow, to red. Are they timed? Is there a sensor, perhaps a small man hiding in the pole controlling it?

In: 7

Answer 1

Depends on the light. Some are on timers, some have pressure plates in the road to sense when a car stops on it, I’ve heard some use metal detectors but I’m not positive on that