Wouldn't be going to Hawthorne. About the only thing they're doing up there is disarming and recycling munitions. DOD flats are used for vehicle transport, frequently by large units. the flats are probably coming, or going to/from the National Training Center at Fort Irwin, CA. Up to division size movements are unloaded at Nebo (Yermo), on the Grounds of the Marine Corps Supply Depot. There have been many Canadian Army Infantry and Armor units cycling through recently, and the 1st Infantry Division was there a few weeks ago from Fort Cambell, Ky, for training preparatory for deployment to Afghanistan. Human assets fly and bus to Fort Irwin, while vehicle assets are brought in by rail, mostly on DOD flats. If not training, then perhaps from the Port of Oakland. Some vehicles are still loaded at the Inner Harbor for Pacific Theatre Destinations, although I'm sure some East Bay railfan would have reported a large number of DOD flats being handled by the Oakland Terminal.

Bill Root