You’re sitting at a red light. It’s 2:00 AM. There isn’t a single other car in sight for miles, but that stubborn red bulb is staring you down like it’s personal. You’ve probably heard the rumors. Somewhere in the darker corners of the internet or from that one "fix-it" uncle, the name mirt traffic light changer comes up.
It sounds like magic. A little box you plug into your cigarette lighter that forces the light to turn green on command. People call it the "Mobile Infrared Transmitter." But before you go scouring eBay with $500 in your hand, you need to know that the reality of this tech is a mess of outdated hardware, massive legal risks, and a lot of modern "smart" cities that will just ignore your signal anyway.
Honestly, the "mirt" is one of those gadgets that lives in the gray area between genius engineering and "how to get a felony in three seconds."
How the mirt traffic light changer actually functions
The concept isn't actually a secret. It’s based on a technology called Emergency Vehicle Preemption (EVP). Basically, when a fire truck or an ambulance is screaming toward an intersection, they can’t afford to wait. They need the light to change now.
Most of these systems, like the famous Opticom systems made by GTT, use pulses of infrared (IR) light. The mirt traffic light changer is essentially a simplified, portable version of the emitters you’d see bolted onto the roof of a police cruiser or a paramedic unit.
Here is the breakdown of the "magic" happening inside the box:
- The LED Array: It’s not just one light. It’s a high-intensity cluster of infrared LEDs. You can't see the light with your naked eye, but to a traffic sensor, it’s like a strobe light at a rave.
- The Timing Circuit: This is the "brain." It makes the LEDs flash at a specific frequency. Usually, this is around 10 Hz for low priority (like city buses) or 14 Hz for high priority (emergency services).
- The Receiver: Up on the traffic signal pole, there’s a little "eye." When it detects that 14 Hz strobe, it tells the traffic controller, "Hey, a fire truck is coming. Drop everything and give them a green."
It’s simple. It’s effective. And it’s exactly why the government hates that you can buy them.
The 2005 law that changed everything
For a while in the early 2000s, you could actually find these things for sale relatively easily. A company called FAC of America started marketing the MIRT as a tool for "authorized users" like funeral directors or volunteer firefighters. Naturally, people who just hated traffic started buying them too.
Then the federal government stepped in.
In 2005, the Safe, Accountable, Flexible, Efficient Transportation Equity Act was signed into law. It added a specific section to the U.S. Code (18 U.S.C. § 39) that made it a federal crime for a "non-qualifying user" to even possess one of these in a way that affects interstate commerce.
If you get caught using a mirt traffic light changer to beat your morning commute, you aren't just looking at a traffic ticket. You’re looking at up to six months in federal prison. If you're the one selling them? That's up to a year.
State laws are often even meaner. In places like Michigan, if you use a MIRT and cause an accident that hurts someone, you could be looking at 10 to 15 years in prison. It’s one of those "high risk, very little reward" situations.
Why a mirt probably won't work in 2026 anyway
Even if you’re a rebel who doesn't care about federal law, there’s a technical problem: the world has moved on.
The original MIRT worked because old traffic sensors were "dumb." They just looked for a light flashing at 14 Hz. If they saw it, they triggered. Modern systems are much more sophisticated.
Encrypted signals
Newer Opticom and priority systems don't just look for a strobe. They look for a specific, encrypted digital code. It’s like a digital handshake. If the vehicle doesn't send the right "password" along with the infrared pulse, the light stays red. Your basic $300 MIRT from a sketchy website doesn't have the encryption keys for your local PD.
GPS and Radio preemption
Many cities have ditched infrared entirely. Instead of light, they use GPS-based systems. The emergency vehicle sends its coordinates and speed via radio or cellular data to a central server. The server then coordinates the "Green Wave" blocks ahead of the vehicle. An infrared MIRT is useless against a system that’s looking for a GPS data packet.
The "Amanet" Confusion
You might see products like the "Amanet Red Light Changer" or "Green Light Triggers" marketed to motorcyclists. Be careful—these are not MIRTs. Those are usually just powerful magnets meant to trip the "inductive loops" (those wire squares in the pavement) that detect a car's metal mass. Those are legal. A MIRT is an active transmitter. Huge difference.
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Real-world risks: It’s not just the cops
Let’s say you have a MIRT and you use it. You think you're being sneaky. But traffic controllers keep logs.
If a light is constantly being preempted at 8:15 AM every Tuesday and Thursday, and there’s no record of an emergency dispatch at that time, the city's traffic engineers are going to notice. They’ll alert local police, who will simply sit at that intersection and wait for the "ghost" emergency vehicle to show up.
Furthermore, you're messing with a complex ecosystem. When you force a light to turn green, you’re often forcing another light to turn red immediately. This can lead to "T-bone" collisions if drivers in the other lane aren't prepared for a sudden yellow-to-red transition.
Moving forward: What you can actually do
If you're frustrated with a light that never seems to see you—especially if you're on a motorcycle or bicycle—don't go looking for a MIRT. It’s a fast track to a jail cell and a device that probably won't work.
Instead, look into Dead Red laws. Many states (like Virginia, Illinois, and Missouri) have "Safe on Red" laws. These allow motorcyclists or cyclists to proceed through a red light after waiting a specific amount of time (usually 120 seconds) if the sensor fails to detect them.
You can also report "lazy" sensors to your city's Department of Transportation. Most cities actually want their traffic flow to be efficient, and they’ll send a technician to adjust the sensitivity of the ground loops or the video detection cameras. It’s much less exciting than having a "magic green light box," but it’s a lot cheaper than a federal defense attorney.
Keep your eyes on the road and leave the infrared strobes to the people with sirens.
Your next steps for better traffic flow
- Check your local "Dead Red" laws: Search for your state's name plus "motorcycle red light law" to see if you can legally move past a stuck sensor.
- Locate the sensors: Look for the cut marks in the pavement (circles or rectangles). Aim to stop your tires directly over the line where the wire is buried for maximum detection.
- Contact 311: If a specific light in your neighborhood is consistently ignoring vehicles, call your city's non-emergency line to request a sensor recalibration.