It happens all the time. You roll up to a signalized intersection but you are without motorized escort to trigger the light sensor. What to do? Some would say treat the light as a stop sign because it failed to be triggered by your bike--But is this true? Did your bike fail to trigger or where you out of position to trigger it?
From my experience in GSO, the lights that aren't on timers (most if not all downtown lights are on timers) are triggered using quadrupole loop magnetic induction sensors. If one of these is functioning correctly it will pick up a bicycle (with the possible exception of bikes with carbon frame, wheels and spokes--they still have steel in the chain) from its steel or aluminum content most notably in the wheel rims.
The trick is to stop your bike on the center pole of the two loops where the detection is strongest. This works great when the loop was installed after the latest asphalt layer was put down but what about when the loops have been covered by later construction like at the confluence of Parkway, Eugene and Bessemer on Bike Route 9? I have had ample opportunity to experiment with that intersection because it is on my commute. I have found in this case you want to stop roughly four feet to the right of the painted lines that separate off the left turn lanes. This would be approximately the center of the lane if the right edge wasn't flared to accommodate right turns.
I have one question for those in the know around here. Who do I need to contact for a sensor that is clearly non-functional? The east bound loop on Bluford at the intersection with Dudley has never worked for me in six months. The west bound loop works so I know the signal is loop controlled.
On Yer Bike!