EcoVelo’s Tip on How to Trigger a Stoplight on a Bike

Traffic Signals on Leavitt

You know how it goes, you’re riding along, having a lovely ride and you come to a traffic signal with a red light – a long red light.  Generally, you obey lights, but this one stays red forever because it’s set to change when there are cars present. You’re no car.. so what do you do?  You trigger the light with your bike as described by the folks at

“On-demand signals use what they call “induction loop vehicle detectors” to sense when a vehicle is waiting at a light. These detectors are essentially metal detectors embedded into the pavement. They work by sensing changes in an electromagnetic field and have nothing to do with the weight of the vehicle. You can often see evidence of loop detectors as lines cut into the road surface just behind the crosswalk.  Wire sensors are embedded in these cut lines, and it’s possible to trigger a light by placing your bicycle wheels precisely on top of one of the wires to disrupt the magnetic field...” You can read the rest of the article here.

I wonder if Chicago streets embed the sensors in the pavement or if they’re located elsewhere due to the weather conditions here that cause the roadbed to expand and contract so much?  I do know that I’m going to look for them tomorrow morning on my commute to work – there’s a very irritating light on my way in that I’d like to try this out on.

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