a fully protective railroad freight car for carrying motor vehicles in a selected one of a bi - level or a tri - level configuration , with the lowest level including a depressed longitudinally central portion between body bolsters of the underbody , which may be a low - level flat car . a pair of vehicle - carrying decks are adjustable in height to provide for either one or two vehicle - carrying levels above the lowest level , while also providing at least a prescribed amount of vertical clearance above each vehicle - carrying deck . ramps may be provided on the lowest level at an end of the car to provide a wheel - supporting surface having a prescribed minimum height . a roof structure is light in weight , and the car has an overall height not exceeding a prescribed limit for operation on most rail lines . the ends of the car are equipped with three - panel folding doors .