Next time you are going East on Kelly Drive to make a left turn onto El Camino Real, you will notice a white circle in the center lane. this has been painted on the tarmac to indicate where the underground loop is buried.
If you put the wheels of you bike on the loop so both wheels touch it the light will change very quickly.
If you notice any other places that need to be adjusted to recognize bikes in Carlsbad, please let me know here and I'll inform the traffic division.
Thanks,
Judy
Judy,
Can you find out how these things work? I've heard magnetism, weight, magic, and karma. :o
Would be interesting to really know form a city engineer how they operate.
Lou...
Lou - That is actually covered in TS 101 ;). Basically, a loop detector is a wire in a loop which has a current running at a constant frequency and when a wheel which has metal in it passes over it, the frequency changes slightly as the metal rims interact with the magnetic field circulating the wire (Maxwell's equations) and is sensed. That's why Pete Penseyres says "tires to the wires". Just roll your wheel on the left or right edge of the loop if you can see it and most lights will trip right away if it is sensitive enough for a bike wheel (if not, contact your local traffic person or Judy!). Works great unless you're full carbon, including rims. Click here for full loop detector details (http://www.marshproducts.com/pdf/Inductive%20Loop%20Write%20up.pdf). Sometimes, the location of the loop is not visible as everything is buried and bike friendly cities help out by putting a marker on the pavement to show where you should roll your wheel to trip that light.
Karl
That's cool.
I was signed up for TS101 last weekend until they cancelled it. Perhaps the next one.
Lou...
https://picasaweb.google.com/106882046756653008139/BikeFacilities?gsessionid=topNEZ_ShrSnhuQdN98-OA#5128456332236943586
Some are magnetic and some now are video. Attached and in the link are some of the types of magnetic loop detectors. Your wheels should be able to set them off if you place them in the sweet spot.