Magnets to Change Traffic Lights

Have you ever been standing at a traffic light and noticed a series of dinner plate-sized circles or squares on the street in front of the light? They're called "inductive loop detectors," and they sense the presence of a large amount of metal. They're used on some traffic lights so that when a car pulls up to the light, the sensor can tell it's there, and the light changes.

What if you're on your bike? Bikes don't have enough metal in them for many older inductive loop detectors to, er, detect them, so unless a car pulls up, cyclists are stuck waiting. "Techiquexpert" Tom Howell and I decided to try something out. Apparently, if you attach a magnet to the bottom of your bike, you can increase the ability of the detector to sense your presence. We decided to check it out in the video below. The results? Um, let's just say we're not becoming investigative reporters any time soon.

BTW, as you'll hear on the show, traffic experts in some cities have responded to this challenge by increasing the sensitivity of the sensors, so they now register the presence of bikes and scooters.


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