Hello fellow cyclists: Thanks to the City for improving the
sensitivity of the traffic light sensors. I encountered this site
which might interest you...

http://www.humantransport.org/bicycledriving/library/signals/green.htm

Key points:
- Roseville uses induction type sensors, which are triggered by the
presence of an electrically conductive material (it doesn't need to be
magnetic, so aluminimum should work fine... not so sure about carbon).
- Usually a bike wheel has enough conductive material content to
trigger a sensor.
- The sweet spot on a single loop sensor is to line up your bike
right over a side wire trace parallel to the road. The sweet spot on
a double loop sensor is to line up your bike along the center wire
trace parallel to the road.