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Old 10-31-03, 10:45 AM   #1
DanFromDetroit
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Traffic sensors for signals

When I am tooling around town, I occasionally run across a traffic sensor that trips a signal red for a cross street, so that I can cross the intersection. These are usually just before the crosswalk and are embedded in the concrete. I used to just ride around in circles waiting for a car to show up and trip the signal because my bike was invisible to the sensor. Well I found that if I stop and lean the bike on it's side so the frame is parallel to the ground instead of perpendicular, then the sensor "wakes up" the light, I pick up the bike and continue on my way. I was so happy with this discovery that I rode around and tripped a few just for fun (I am easily amused, I guess).

My frame is made of steel. I was wondering if anyone can confirm this works with an aluminum frame as well.

Dan
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Old 10-31-03, 11:02 AM   #2
JasBike
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I would imagine the camera just looks for a certain % of the ground in its view to be covered, and assumes that's a car.
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Old 10-31-03, 11:12 AM   #3
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Quote:
Originally Posted by JasBike
I would imagine the camera just looks for a certain % of the ground in its view to be covered, and assumes that's a car.
I was under the impression that the traffic sensors embedded in the pavement were run under an electro-magnetic circuit. When a car stops over one of the sensors, the metal of the car trips the circuit and changes the light. If this is true, it seems that laying the bike down over the sensor would have created more surface area to trip the magnetic sensor. Just a thought...
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Old 10-31-03, 11:31 AM   #4
DanFromDetroit
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Quote:
Originally Posted by thetray
... more surface area to trip the magnetic sensor ...
I think you are right. I was wondering if an aluminum frame would trip the sensor as well. I sort of doubt it, but I was wondering if anyone has tried it.

Dan
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Old 10-31-03, 11:35 AM   #5
Prosody
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My aluminum frame trips sensors just fine. If you can see the cuts in the pavement where the wires are imbedded, ride and stop along one to trip the sensor. If there are three cuts, ride and stop over the center one.
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Old 10-31-03, 11:42 AM   #6
Gojohnnygo.
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Quote:
Originally Posted by Prosody
My aluminum frame trips sensors just fine. If you can see the cuts in the pavement where the wires are imbedded, ride and stop along one to trip the sensor. If there are three cuts, ride and stop over the center one.
If that fails unclip and place your shoe cleat down on the sensor.
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Old 10-31-03, 12:04 PM   #7
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The induction loop works when an electrical conductor moves over, so an aluminum bike should work better than a steel bike since aluminum is a better electrical conductor than steel.
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Old 10-31-03, 12:30 PM   #8
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I have a carbon bike that never trips any sensors. Like gojohnny said though if I un-clip and put my shoe right on the line I can "fool" the sensor.
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