CAYCE, S.C. — As they begin to investigate the circumstances of the fatal wreck in South Carolina, officials have already settled on one thing: that the crash between a passenger train and a freight car could have been prevented with technology already installed in parts of the nation.
It’s been a decade since Congress approved a law mandating the GPS-based system called ‘‘positive train control,’’ which is designed to prevent two trains from traveling on the same track at the same time.
That’s what happened early Sunday in Cayce, S.C., when a locked switch sent a New York-to-Miami Amtrak passenger train onto a side track where an empty CSX Corp. freight train was parked.
Two Amtrak employees, a conductor and an engineer, were killed and more than 100 passengers were treated at hospitals for injuries. It was the third fatal Amtrak train crash in less than two months.
‘‘An operational PTC is designed to prevent this type of incident,’’ National Transportation Safety Board Chairman Robert Sumwalt said Sunday, of positive train control.
Industry experts and rail companies say the delays in installing the technology mainly come down to costs and the sheer size of the rail system.
After a collision between a commuter train and a freight train in Chatsworth, Calif., that killed 25 people, Congress in 2008 passed a law requiring railroads to adopt the technology on all tracks that carry passenger trains.
A requirement for freight trains used to haul liquids that emit toxic gas if spilled was prompted by a 2005 train wreck in Graniteville, S.C., in which nine people were killed and more than 250 were treated for toxic chlorine exposure.
Positive train control relies on GPS, wireless radio, and computers to monitor train positions and automatically slow or stop trains that are in danger of colliding, derailing due to excessive speed, or about to enter track where crews are working or that is otherwise off limits.
Railroads were given seven years to install the technology for the nation’s 20,000 locomotives and 60,000 miles of track.
But when it became clear that few if any railroads would meet the deadline, Congress extended it another three years to Dec. 31, 2018, with the option to grant railroads that show progress an additional two years to Dec. 31, 2020. Several freight railroads have told the government they won’t be able to meet the 2018 deadline.
Overall, freight railroads have implemented PTC on 56 percent of required route miles, according to the Association of American Railroads. The association said it’s not clear yet how many of the seven large freight railroads in the country will require extensions.
A handful of the nation’s 27 commuter railroads have already received extensions past the Dec. 31 deadline, and more extensions are expected, according to Randy Clarke of the American Public Transportation Association.
Clarke also said Monday that, although Congress first required railroads to adopt the safety technology 10 years ago, it took many years to develop the safety systems and to submit and win Federal Railroad Administration approval.
In some areas of the Northeast, where Amtrak owns both railways and locomotives, the company has been able to set up PTC. But in areas like South Carolina, the tracks are owned by freight companies like CSX, on whom they must rely to implement the technology.