It is stealing. That land belongs to some entity. If it is abandoned, the land may have been sold at a real estate auction and the person who bought that land where the rail line once stood may not care what is on it, but it is still their property. Think of it this way. Picture yourself "rescuing" a few railroad related items from an abandoned rail line. Just then a police officer drives by. You just got BUSTED! Wouldn't you feel pretty ridiculous explaining to the person bailing you out and to your family and friends why you were arrested? I do not think "It would have looked great on the wall of the train room" will fly. It is stealing, flat out. Those items legitimately belong to someone.