tankeroilcar BILLINGS, Mont. (AP) – Following a string of explosive accidents, federal officials say crude oil being shipped by rail from the Northern Plains across the U.S. and Canada may be more flammable than traditional forms of oil. The U.S. Department of Transportation issued a safety alert today. It warns the public, emergency responders and shippers about the high explosive potential of crude being shipped from the Bakken oil shale patch in Montana and North Dakota. The warning comes in the aftermath of the massive explosion caused by Monday’s oil train derailment near Casselton, N.D.