Lessons learned as a former commuter.  Most traffic signals use an induction loop to trigger for vehicles.  You can frequently see where they've installed them in the pavement. If it is a 3ft diameter circle, you want to be on a chord about ten inches from a tangent point parallel to travel.  Some cities will put a bicycle mark at this point.  If it is a rectangle, usually riding on one side leg will trigger it.  If they have the signal cranked down so it does not detect a bicycle it will probably have trouble detecting a motorcycle.  Sometimes they put the loops a two or three car lengths away from the crosswalk so if you know where they are you can slow down as you ride over them to trigger the light.  I was told by an EE friend that even aluminum pedals should be able to trigger an induction loop set correctly.