The economic motivation for rail-ship is interesting. As the spread between WTI and Brent increases, and Bakken and WCS oil are subject to increasing headwinds with storage filling, the rationale for rail shipment to access international pricing increases. West Cdn Select is trading around $39/bbl, so putting it on a train to the east coast for the Brent market is well worth the effort to earn more profit.
I'm of the opinion that Bakken oil should not be rail shipped. They are not processing most of it for volatiles and the crude is explosive. This is not the case with Texas Permian shale oil, and certainly not oil sands. If the Cdn gov't had any spine, they would stop it at the border.