Pretty sure the below pavement sensors around here use old fashioned metal detector technology, which is a coil and a tuned circuit that detects via a capacitance shift when metal is proximate. A magnet will help in that it's just a little more metal, but I don't think the detection system is using magnetism or requires ferrous metal.
By situating my machine over the left or ride side of the approx 4x4 patch in the pavement, I can put it's metal closer to the coil, which is a big horizontal loop and then have a better chance of being detected. This seems to work, but I haven't done any kind of scientific test. Mostly, if I'm the first to arrive at one of the intersections where I know one of these sensors lives, I pull far to the right and encourage the next car to move to the front. There's never a much of a shortage of "next cars" here in Chicago.
Chicago also has a fairly recent law on the books that allows bicycles and motorcycles to proceed through a red light after 120 seconds of waiting, if the light shows no sign of changing, and the way is clear. It's like the red light becomes a stop sign, legally speaking. The law specifically references the fact that motorcycles may be unable to activate the sensors.
I guess there's at least one benefit to living in the big city.