Abstract: A method of making a support arm includes heating a mold to a glass transition temperature of a thermoplastic material; injecting the thermoplastic material comprising a filler into the mold and allowing the thermoplastic material to conform to the mold; cooling the mold to an ejection temperature to form the support arm; and ejecting the support arm from the mold; wherein a cross-section of the support arm taken along a line from an inner edge to an outer edge of the support arm comprises a first “U” shaped portion and a second “U” shaped portion.

Abstract: A sliding door is provided for a rail car of the type having a floor, a side wall along one side of the floor and standing upwardly from the floor and an opening in the side wall. The sliding door is mounted on top and bottom rails at the opening extending parallel to a plane of the opening with the door movable from a closed position at the opening to an open position spaced along the rails from the opening. The sliding door is formed of modular panel sections which are replaceable independently of one another when damaged. The sliding door includes a flexible portion being movable between a relaxed position and a flexed position in which the flexible portion is deflected in a direction transversely to the plane of the opening in relation to the relaxed position in order to minimize damage to the, door when impacted.