25 rail cars that came off the track were carrying fracking sand.
TSB investigation determines the derailment caused by excessive truck hunting on the empty centre beam bulkhead flat car.
No reports of injuries or fire, but homes in the area have been evacuated.
Transport investigator is urging Transport Canada to quickly introduce enhanced standards to reduce the risk of spills.
Up to 17 of the 100 tankers loaded with Bakken crude from North Dakota caught fire or exploded.
New rules require that at least two crew work a train transporting dangerous material such as crude oil.