This Dude Explains How Traffic Lights Really Work Because It’s His Job

At first glance, traffic lights are stunningly simple: green means go, red means stop, and yellow means it’s about to turn red. But like cars, phones, and just about everything else on this planet, they have become more complicated in recent years due to advancements in technology. Your know-it-all uncle will tell you he knows exactly how they work, but unless he’s seen these videos from a guy who works on them every day, I kind of doubt it.

The Trafficlightdoctor is a guy named Steven who works as a traffic signal technician in Mississippi. He also has big followings on Facebook, Instagram, and TikTok. Some of his videos explore the technical side of a traffic light, like how each unit is wired, while others aim to dispel myths. It might seem niche but it gives rare insight into an everyday part of life that most people never think twice about.

For example, the camera that you sometimes see perched above a row of traffic signals isn’t there to catch you if you run a red light. In a short video, the doc explains that it’s pretty much a motion sensor. The camera detects the number of cars in a given intersection and their position in a lane. He opens a controller box and shows what the camera sees: lines of squares that are white when they’re empty and blue when occupied. If no one’s waiting, there’s no use slowing down traffic coming the other way so the light stays red. If cars are waiting, the camera tells the controller to trigger a green light. That doesn’t mean red light cameras don’t exist, but they’re not as common as some might assume.

Have you ever wondered why your light never seems to turn green? It’s not a clever plot to make you late; it might be related to your position in the intersection. In a separate video, Trafficlightdoctor Steven shows a white pickup that’s almost entirely parked in the intersection rather than behind the line. Here’s when the aforementioned camera enters the plot: its job is to detect cars, and the truck is parked too far forward for the camera to tell it’s there. It picked up the car behind, so it knows there’s someone waiting, but otherwise, the driver might be waiting a long time.

If you’re especially nerdy, you’ll be even more interested in the layout of the roadside traffic signal cabinets. There’s some seriously impressive wire and cable organization inside—the type of stuff you see on this unfortunately named yet deeply satisfying subreddit. That uncle of yours would be in way over his head if he cracked one of these open… unless this guy is your uncle, I guess.

All told, the videos illustrate how advanced traffic management has become. What’s a roundabout?

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