How could that happen? All railroad structures are built to height and width standards?
A lot of railroad infrastructure is old and as a result, not all of it is built to modern standards. Saw this firsthand many years ago when a doublestack intermodal train was sent down a track with inadequate clearance. The engineer was smart enough to slow down before it became a real issue...
Autoracks are also overheight - look at a locomotive hauling them and you will see the car is taller than the locomotive...