You're sitting in the car, watching the red light. It feels like forever. You start wondering: is someone watching? Is the light FX1? How does it know when to turn green?

Here's the secret: buried in the road under your car, there's a loop of wire. It's called an induction loop, and it's basically a metal detector — except instead of hunting for treasure, it's hunting for cars.

When your car rolls over that loop, something invisible happens. The car's big metal body changes the magnetic field around the wire, the same way a spoon affects a magnet. The loop feels the change and sends a signal: "Car here!"

That signal zips through a cable to a metal box by the roadside — the traffic controller. Think of it as the light's brain. It's keeping track of every loop at the intersection, like a chess player watching the whole board.

The controller has a plan, a recipe for when each light turns green. But it's not rigid. When it gets the "car here!" signal from your direction, it thinks: "Okay, someone's waiting. I'll give them a green soon."

Meanwhile, the cross street might have ten cars waiting. The controller has to be fair — it gives each direction enough green time based on who's there. If nobody's waiting on the cross street, your light turns green faster. If there's a crowd, you wait a bit longer.

Some lights don't use loops at all. Instead, a camera mounted above the intersection watches for cars like a hawk, or a radar sensor bounces invisible waves off vehicles. Same idea, different trick: the controller just wants to know where you are.

So the light isn't ignoring you. It felt you arrive, added you to its list, and it's working through its plan. The wait feels long because you're just sitting there — but to the controller, it's all happening in perfect, fair order.