How Traffic Lights Work

Gamer Julian Hawkins quite knowledgeably broke down every element of a typical traffic light in the United States, noting that these lights don’t know why they are changing, but nonetheless, know when they need to change.

You see them every day. You stop at them, you wait, you go, and that’s about as far as it goes. ….this isn’t really a light. What you’re looking at here is just a visible part of a much larger system. This is an output device. It doesn’t make decisions. It doesn’t know anything about traffic. It doesn’t even know what color it’s showing. It just turns on when it’s told to. 

Hawkins also explains how the lights are timed to work with traffic and how a network of sensors keeps pedestrians and drivers safe.

I break down how traffic signals really operate, including how phases and timing work, how pedestrian signals and countdown timers function, and what’s actually happening behind the scenes in a real intersection.

via Tom Scott