The Southeastern Pennsylvania Transportation Authority tests its Positive Train Control system at the agency's rail yard near Malvern, Pa. The system will cost SEPTA about $328 million. The regional passenger railroad is one of the few in the country that are on track to meet an end-of-the-year deadline for installing PTC. Jeff Brady/NPR hide caption

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Emergency personnel search through the wreckage of an Amtrak train that derailed Tuesday night in Philadelphia, killing at least five people who were on board. Joseph Kaczmarek/AP hide caption

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A fireball goes up at the site of an oil train derailment in Casselton, N.D., in this Dec. 30 photo. The fiery crash left an ominous cloud over the town and led some residents to evacuate. Bruce Crummy/AP hide caption

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A fire burns west of Casselton, N.D., Monday, after oil tanker cars exploded following a train derailment. No one has been reported hurt in the derailment or fire. But officials are recommending residents of the town to stay away from the potentially toxic smoke. Ken Pawluk/AP hide caption

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