In this July 6, 2013 file photo, emergency workers examine the aftermath of a train derailment and fire in Lac-Megantic, Quebec. Forty-seven people were killed. U.S. federal regulators are further tightening testing requirements for companies that transport oil by rail after a spate of explosions caused by crude train derailments in the U.S. and Canada. The action on Thursday, March 6, 2014 from the U.S. Department of Transportation builds on a Feb. 25 order that targeted oil shipments for more stringent testing. THE CANADIAN PRESS/Ryan Remiorz