Ever since Hurricane Katrina swept across the Deep South in 2005, shredding the region’s railways, it’s been impossible to take a train heading east from New Orleans to the rest of the Gulf Coast. For years, Amtrak has been trying to restore service in the form of a twice-a-day line between New Orleans and Mobile, Alabama. But it’s met fierce resistance from two rail giants — CSX and Norfolk Southern — which own most of the tracks that the agency wants to use.