The federal government said only three companies have voluntarily turned over data on the from North Dakota, despite requests for this information dating back to January. The U.S. Department of Transportation said Friday that Exxon Mobil Corp. , Continental Resources Inc. and Savage Services Corp. had shared testing data, but none of the many other producers or shippers active in the area had done so. The government is seeking data on the crude after a series of railroad accidents in which oil exploded, including one in that left more than 40 people dead. Historically, crude hasn’t erupted into fireballs, raising questions about the composition of the oil from the Bakken. In January, Transportation Secretary Anthony Foxx said the oil industry had agreed to share testing data about the , but since then the government and industry have disagreed over what was promised. The amount of oil moving by rail […]