Then what do you think the long embankments and cuts into the sand are, as they are located right where maps and aerial imagery has shown the railroad to have been.

It would be nice if there was a crane railroad criteria, but such is life. As for the ruins bit, mapping it as a former military area makes it show up on the map, so I was trying to go with the best option that I could think of. If you can suggest a better option, please do.