In Topping v. CSX Transp., Inc., 1 F.3d 260 (4th Cir. 1993), the employee was injured when he fell over a piece of loose metal in a locomotive . The piece of metal was not where it should have been and was of unknown origin. Nevertheless, the Fourth Circuit Court of Appeals, after noting that the defenses of contributory negligence and assumption of risk are not available to a defendant in a BIA case, stated that the facts of that case presented "... a classic jury question whether the presence of the loose metal object rendered the locomotive cab 'unsafe to operate.'" Id. at 261.