WASHINGTON, DC - JULY 11: Anthony Foxx speaks after being ceremonially sworn in as Transportation Secretary, at the U.S. Department of Transportation, July 11, 2013 in Washington, DC. Foxx, the former mayor of Charlotte, North Carolina, was officially sworn in on July 2 and is the 17th Secretary of Transportation in U.S. history. National Journal

The Transportation Department on Tuesday issued a requirement for proper testing and classification of crude sourced from North Dakota's Bakken formation before rail shipment in an effort to boost safety in the wake of a series of recent derailments.

"Today we are raising the bar for shipping crude oil on behalf of the families and communities along rail lines nationwide — if you intend to move crude oil by rail, then you must test and classify the material appropriately," Transportation Secretary Anthony Foxx said in a statement.

Spot tests conducted by the department's Pipeline and Hazardous Materials Safety Administration have shown that mislabeling and improper classification of crude-by-rail shipments may be widespread. The Obama administration says this is a concern because Bakken crude may be more explosive than conventional oil, a quality that necessitates strict oversight to ensure safe transport.

Crude-by-rail safety has come under the microscope following a number of accidents in the past year involving trains hauling Bakken crude. At the end of December a train carrying crude derailed near Casselton, N.D., sparking a massive fireball.

Amid fiery explosions and derailments, DOT has been the subject of criticism from lawmakers and the private sector for failing to expedite a rulemaking that would improve the safety of DOT-111 tank cars, a type of car frequently used to move crude.

In response, the department has moved forward with emergency orders, including the one issued Tuesday, to tighten safety standards in the absence of a final rulemaking. The order also states that shippers cannot use the lowest-strength tank car that would normally meet shipping requirements.

"When you do ship it, you must follow the requirements for the two strongest safety packing groups. From emergency orders to voluntary agreements, we are using every tool at our disposal to ensure the safe transportation of crude," Foxx said.

The emergency order arrives just prior to an oversight hearing set to be held on Wednesday by the House Transportation and Infrastructure Committeee Railroads, Pipelines and Hazardous Materials Subcommittee that will examine passanger and freight rail safety. 

PHMSA administrator Cynthia Quaterman is one of the witnesses set to testify at the hearing. 

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