You arrive at a railroad crossing when a train is approaching. Where must you stop?

Under Tennessee law, when a train is approaching a railroad crossing, you must stop between 15 and 50 feet from the nearest rail. Never try to beat the train through the crossing. A train can't yield the right-of-way to you. [Stopping for Railroad Crossings, Stops Required by Law, B-4. Rules of the Road, Tennessee Comprehensive Driver License Manual]