Schwartz from Jefferson County writes, “What is driving you crazy? Why don't the traffic signals trigger off of my motorcycle?”
This is a question I get now and then. You’ve probably seen those cuts in the road where you stop at the light. When I ask people how it works, most drivers think it is by weight, sensing the weight of the car when it stops at the light.
It is actually triggered by a device called an inductor loop. It’s basically a wire placed in the asphalt leaving that telltale rectangular cut in the road that operates by sensing a change in frequency to the electromagnetic field over the coil of wire. In other words, when a car pulls up, it senses the vehicle and the light changes.
Most motorcycles, scooters, bicycles and small cars don't have enough conductive material to trigger these loops and change the traffic light.
Most riders approach intersections in the wheel tracks because they don’t want to sit in the goop that drips down from cars waiting at the light. Unfortunately, most inductor loops are not made narrow enough to detect motorcycles sitting in this position.
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One trick some use to fool the system is to attach a very powerful magnet on the bottom of the motorcycle that will trigger the sensor and change the light. There are mixed feelings about that technique.
Twelve states have a law called “safe on red” that allow motorcyclists to run through the red light as long as they stopped first. Some states require riders to come to a full stop, while others make them wait for a full rotation of light changes and some require riders to wait up to two minutes.
One system that works much better most of the time are overhead cameras.
They look like video cameras but they use electromagnetic waves, or acoustic sensors to detect the presence of vehicles at the intersection waiting for the light. They sometimes work better for motorcycles than inductive loops. They are often easier and more cost effective to install than cutting the road and embedding the inductive loops.
I’ve heard that installers like these because it is safer for them. They are also a smarter way to change the lights and can help with real-time traffic management.
Denver7 traffic reporter Jayson Luber says he has been covering Denver-metro traffic since Ben-Hur was driving a chariot. (We believe the actual number is about 20 years.) He's obsessed with letting viewers know what's happening on their drive and the best way to avoid the problems that spring up. Follow him on Facebook and Twitter.