linear skirt

A propulsion device attached to the underside of all police cars that allows the cars to drive on linear railway tracks. It is part of a bimodal system, letting police officers use the tracks to bypass accidents or traffic jams in an emergency. However, this is only permitted in the event of an absolute emergency, due to the wear this causes to the tracks. Other vehicles such as ambulances and linear railway maintenance cars are also equipped with a linear skirt.