Pennsylvania Gov. Tom Wolf has hired a railroad expert to look into the threat of moving Bakken crude oil from North Dakota to the East Coast.



Such shipments pass through Pennsylvania, Ohio and other states.



Wolf has directed University of Delaware professor Allan Zarembski to look into the issue in the next three months.



Pennsylvania has seen four train derailments and spills since January 2014.



Click  here  to read more from NPR's StateImpact Pennsylvania.



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