Safety rules will probably be tightened on crude oil shipments from North Dakota following a string of railway explosions, threatening to damp an energy boom that has boosted the region’s economy. U.S. regulators issued a safety alert after a train carrying oil crashed and caught fire earlier this week in North Dakota, where surging production has helped lead a renaissance in domestic energy and driven the state’s unemployment rate to the nation’s lowest. The type of oil pumped from the shale formations of North Dakota may be more flammable and therefore more dangerous to ship by rail than crude from other areas, the Transportation Department said in the alert. Regulators are considering imposing tougher rules on railcar construction, among other things, potentially raising the costs of moving the crude to market. Pipelines could be affected as well. “Regulators have to take heed that anything they do is going to […]