The requirement applies to Amtrak and 25 commuter railroads, which together carry 564 million passengers annually, and the track they share with freight trains. It also applies to freight-only trains and tracks used to transport a category of hazardous materials poisonous to breathe, in response to a 2005 collision of two Norfolk Southern trains in Graniteville, S.C. A chlorine gas tank car was derailed and punctured, releasing a toxic cloud. Nine people were killed and hundreds injured. A textile plant that employed most of the town's residents was severely damaged and closed.
But pressure from industry has eroded the law's reach. Initial estimates were that positive train control would cover about 70,000 miles of track — less than half the nation's total. Now, that figure has shrunk to 50,000 miles. Regulators have given railroads permission to install less expensive PTC systems that won't prevent certain rear-end and low-speed collisions.
Freight railroads have campaigned to exclude tracks used only a few times a year to transport poisonous-to-breathe cargo. They also want to reroute trains containing such cargo to track shared with passenger trains, further reducing the amount of freight-only track that has to be equipped with PTC, said Grady Cothen, a former railroad administration official.
A weakness of the 2008 law is that it doesn't cover other types of dangerous cargo, including crude oil and ethanol, Cothen said. Last month, an unattended train transporting 72 cars of crude oil came loose, hurtling down a 7-mile incline before derailing and igniting in the lakeside Quebec town of Lac-Megantic near the Maine border. The fiery explosion killed 47 people, and destroyed much of the town.
PTC wouldn't have prevented that accident, but the disaster underscores the risks of such shipments. U.S. railroads moved 178,000 crude oil carloads in the first half of this year — twice the number during the same period last year and 33 times more than during that period in 2009.