One of these.
I was exiting the parking garage in the building I work at behind a car and the magnetic sensors didn't pick me up on my Tuono. The barrier started raising and the gate arm began to lower.... Luckilly it was a solid ramp that raised up (not a bar, like shown above) and I was traveling in the opposite direction than the arrow in the picture... I had to fuckin gas it & jumped the damn thing.
Definitely got my attention!