I have worked for the railroads for 38 years. I am well aware of how they treat scrap thieves. The key to finding used rail is to find a industry that has closed and is no longer using the tracks to their warehouses. Most of the time, but not always, the industry owns the tracks that service their industry. This means the rail, ties, tie plates, spikes, joints all belong to them and not the railroad that services them. All it takes is talking to the business managers and secureing permission, or a purchase, and I have even been paid by the business to remove the track. Usually their is signage indicating the limits of railroad maintenance, sometimes on old sidings the signs might not be present, but is usually located beside or close to the derail that protects the mainline from rollouts. Any material removed from the business location will require a bill of sale or proof of ownership if the material is intended to be sold for scrap. Scrap yards generally wont accept railroad material and will report anyone trying to sell them such material.