Have you ever wished you could make the traffic signal turn green with just the push of a button? For some drivers this isn’t just a dream. When necessary, the standard operation of traffic signals can be altered through an optical communications system called traffic signal preemption.

Being delayed by red lights is merely an inconvenience for most of us, but it can be a matter of life or death for a person who is waiting for an emergency responder to arrive. In order to clear the way for emergency vehicles, signal preemption transmitters can change a red light to green or extend an existing green light. These transmitters are standard equipment on many emergency response vehicles.

Here’s how it works:

1. An emergency response vehicle approaches within approximately 1800 feet of a preemption-equipped traffic signal.

2. The preemption detector “sees” the emergency vehicle’s transmitter and initiates the signal preemption process.

3. Standard traffic signal operation resumes once the emergency vehicle has passed through the intersection.

If you want one for your own car, you are out of luck. To prevent unauthorized use, operation of these devices is strictly monitored.