How To Turn Red Lights Green

A handheld gadget and a few bucks worth of LEDs will convince traffic lights you're an ambulance. Just don't come crying to us when you're arrested for it.

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We’ve all been there. You’re sitting at a red light, waiting. Waiting. Waiting. It starts to feel like you’ll never get your chance to go, like you’ll live and die in this intersection without ever moving an inch. You begin mentally writing your will, waiting for starvation to set in, when an ambulance creeps up in your rear-view mirror.

Suddenly, the light is green. The ambulance, by its very arrival, stunned your immutable traffic light into allowing safe passage for your lane of travel. “How did it do that,” you wonder, “and how can I do the same?” As it turns out, the answer is refreshingly simple — and deeply illegal.

Flipper Zero Controlling Traffic Lights

The kind folks over at The Drive turned us on to the exploits of Peter Fairlie, a hacker and tinkerer on YouTube. Fairlie’s done a number of projects involving the Flipper Zero, a sort of Swiss Army knife for electronic experimentation — RFID, infrared, radio transmission; you name it, the Flipper can do it.


But the Flipper, on its own, can’t control a traffic light. Rather than radio waves, emergency vehicles use light to communicate with traffic lights — infrared lights, with enough luminance to cut through even the sunniest of days while remaining unseen by the human eye. The Flipper’s infrared LED is powerful enough to control nearby devices, but Fairlie realized that a traffic light would require much more.

So, Fairlie wired in the infrared LED array from a security camera. He knew what flash frequencies the traffic lights near him would look for — 10, 12, and 14 Hz — so he set the Flipper to generate that frequency and sent it out over GPIO pins. With the more powerful infrared array cycling at the proper rate, Fairlie had built a DIY emergency vehicle transmitter — he could snap his fingers and turn red lights green.


While this is an interesting project, it is of course extremely illegal. 18 USC §39, covers the offense, which carries a fine or a prison sentence of up to six months — or both. Building these devices for others is even worse, with the sentence rising to a year for any individual caught selling a “traffic signal preemption transmitter.”

So, yes, you can change the lights on your daily commute. It’s not even that hard, with a bit of technical knowhow and a soldering iron. Just, don’t actually go out and try it — we can’t get your clicks if you’re in jail.