Browsing around for bike-related goodies today, we came across this brilliant example of proletariat problem-solving in the name of an improved urban cycling experience. They call it the Traffic Loop Sensor Activator, or sometimes U.S. Patent #7,432,827--we call it a nice alternative to sweating for minutes at a time in the midst of high-speed traffic, waiting for a green light that never comes.
The gadget, depicted above, directly triggers the inductive sensors embedded in the roadway at many intersections, by creating a strong but short-lived magnetic field that simulates the presence of a much larger conductor--like the steel body of a car. Note that it's not an always-on kind of deal; the cyclist must press a button to activate it when centered over the telltale two-rectangle groove of the induction sensor coil, but it's a heck of a lot better than hoping for a car to come along and rescue you, or risk running a red light with an excuse no dedicated motorist is going to believe.
Obviously clunky and big, we'd love to see a sleeker version integrated into a few of the growing multitude of "urban commuter" bikes being trotted out lately, if only out of pure self-interest. We've gotta wonder, though, what the prototype testing looked like for this one. Late night intersection inspections maybe?
>>Read more about it, and get directions for building your own (if you're nerdy enough)
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Yea it may be heavy but you could use the battery for lights or even attach a generator... that would be epic at a critical mass meet up.
mngrif is right. I had one on my motorcycle many years ago, so I also put one on my bicycle. Never again will I have to wait for a car to come up behind me to change the traffic light to green so I can go.
BTW, Chris has it spot-on. The vast majority of loop sensors can be triggered, even on a full-carbon-frame bike, by sitting right on top of one of the loop wires. You don't have to be magnetic (ferrous), just conductive, and even lightweight aluminum-rim wheels fit the bill.
Once again, an answer looking for a question. ;-)
Simply place the tire inline with the direction of the sensor wire (tangential to the sensor loop in the road). The wheel sets up a field that will trigger the sensor. Believe it or not, it actually works better for aluminum rims.
I hardly ever seem to have a problem with getting "forgotten" by the sensors -- maybe twice a year. I either run it or go down the crosswalk toward the crosswalk buttons.
Yes, there were many late night missions to certain obstinate intersections.
One thing I want to clear up....the device does not just make a strong, short-lived magnetic field; it scans around to find the frequency of the loop sensor, itself, and transmits back a mag field at or near that frequency. The frequency is key.
And, yes, you're seeing a clunky prototype. It can be made much smaller.