I don't know either. Amtrak's Cardinal runs through the New River Gorge in WV, but the CPHRHS in Huntington still runs their New River Gorge Fall Foliage trains every year, with Amtrak equipment. There doesn't seem to be any problem with that relationship. It was this last weekend, in conjunction with Bridge Day, when pedestrians and BASE jumpers are allowed on the NRG highway bridge.
One year quite a while back one of the jumpers landed on top of the Fall Foliage train, and they had to stop to get him and his parachute off...