Pressure sensitive I reckon.
Is there a cross pattern of tar banding on the floor? If so, jump up & down on the pegs on approach to the solid white line, as under these lines there's a pressure sensor.
Cars are heavy enough to kick the sensor in, bikes often aren't
There's a set of lights like this near me.
There's another trick that usually works. Creep slowly across the tar banding, less than 10mph. By the time you get to the lights, they've changed, and quicker than you waiting 10mins.
EDIT: There is another way, but its slightly naughty & takes a little faffing to get right. Flash your headlights at just the right frequency.
EDIT2: I figured they were pressure sensative matts (since that'd be a reasonably cheap way to do things), but induction loops would work equally.