Federal investigators are trying to figure out why a rail switch was in the wrong position, sending an Amtrak train into a freight train and killing a conductor and an engineer in South Carolina.
But they already know what could have prevented the wreck that injured more than 100 passengers: a GPS-based system called "positive train control," which knows the location of all trains and the positions of all switches in an area, and can prevent the kind of human error that puts two trains on the same track.
"It could have avoided this accident. That's what it's designed to do," said National Transportation Safety Board Chairman Robert Sumwalt.
Regulators have demanded the implementation of positive train control for decades, and the technology is now in place in the Northeast, but railroads that operate tracks used by Amtrak elsewhere in the U.S. have won repeated extensions from the government. The deadline for installing such equipment is now the end of 2018.
CSX Corp. — the freight railroad operator that runs the stretch of track in the South Carolina crash — issued a statement expressing condolences but said nothing about the cause.
"Business as usual must end," Democratic Sen. Richard Blumenthal of Connecticut said after the crash.
Sumwalt said the passenger train hurtled down a side track near Cayce around 2:45 a.m. Sunday after a stop 10 miles north in Columbia because a switch had been locked in place, diverting it from the main line. A crew on the freight train had moved the switch to drive that train from one side track — where it unloaded 34 train cars of automobiles — to the side track where it was parked. The switch was padlocked as it was supposed to be, Sumwalt said.
The system that operates the train signals in the area was down, so CSX dispatchers were operating them manually. Sumwalt said it was too early to know if the signal was red to warn the Amtrak crew that the switch was not set to continue along the main train line.
Just hours after Sunday's crash, which sent 116 of the 147 people on board the New York-to-Miami train to the hospital, Amtrak President Robert Anderson said there must be no more delays from the federal government in installing the safety system by the end of 2018.
He deferred to investigators about whether the system would have stopped this crash. "Theoretically, an operative PTC system would include switches in addition to signals, so it would cover both speed and switches," Anderson said.