What is positive train control, and could it have prevented the Amtrak crash?

02:05 - Source: CNN
Could technology have stopped train derailment?

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Safety advocates have pushed for PTC for decades, but efforts have stalled over its cost

PTC installed but not operational yet on segment of tracks where train derailed

CNN  — 

The Amtrak passenger train didn’t have a safety technology called the positive train control activated at the time it derailed in Washington state, said Richard Anderson, the rail service’s president and co-CEO.

Positive train control, or PTC, can automatically slow down and stop a train if it senses the locomotive is going too fast or could get into an accident. The Federal Railroad Administration has called the system the “single-most important rail safety development in more than a century.”

The crash, which killed two Amtrak employees, raises familiar questions about what PTC is and why it’s still not implemented across the country.

For decades now, railroad safety experts have pushed for it, and Congress passed a law mandating it in 2008. But here’s why that hasn’t happened yet.

How does PTC work?

It’s a system that combines GPS, wireless radio and computers to monitor trains and stop them from colliding, derailing or speeding.

“We consider it an angel on our shoulders out there on the track, and it’s our backup and our safety net,” said John Hyatt, a former railroad engineer.

PTC was designed to prevent the human errors behind about 40% of train accidents by ensuring that it’s being operated in accordance with signals, speed limits or other rules, rail safety experts say. It’s an integrated system using tracks and train.

For example, if a train engineer doesn’t see a curve coming or a spot where the train is supposed to slow down, signals are sent to the train and “it will begin applying the brakes on the train to get it down to that speed which is required, or stopping the train,” Hyatt told CNN.

The NTSB has recommended the use of PTC for decades.

Why wasn’t PTC activated?

PTC was installed on the segment of tracks where the Amtrak Cascades 501 derailed, but it wasn’t operational yet, said Geoff Patrick, spokesman for Sound Transit, which owns the tracks where the derailment occurred.

The technology needs to be installed in trains as well the tracks, because a computer system knits both the car and tracks together, Patrick said. The target date for having the PTC up and running for the segment of the track in the December crash had been the second quarter of 2018.

Amtrak has equipped 71% of its locomotives and 67% of its tracks with PTC, according to Federal Railroad Administration data from the third quarter of 2017.

Why isn’t PTC mandated throughout US?

Railroad companies have until the end of 2018 and possibly two more years afterward to implement PTC.

Advocacy for PTC has gone on for decades, but efforts have stalled over the costs.

In response to a 2008 head-on collision that killed 25 people near Los Angeles, Congress passed a law ordering the nation’s railroads to adopt PTC by December 2015.

The railroad industry has opposed PTC because of its high cost and technological issues.

As 2015 came to a close, several railroad companies threatened to shut down services unless Congress gave them more time, maintaining the deadline wasn’t realistic given the complex technology.

So Congress extended the deadline, giving companies until December 31, 2018, with extensions up to 2020 if certain requirements are met. The delay left some safety advocates fuming.

“The reason why they’ve been given so many extensions has been money,” said Mary Schiavo, a CNN analyst and a former Department of Transportation inspector general. “It is expensive to put it on tracks all over the country.”

The Association of American Railroads estimated that freight railroads had spent $8 billion and passenger railroads $3.5 billion to meet the PTC mandate, as of March 2017.

Could PTC have prevented this derailment?

That remains to be seen as the investigation gets underway.

NTSB board member T. Bella Dinh-Zarr has noted that PTC doesn’t guarantee 100% safety.

PTC can’t prevent accidents if there’s trespassing onto the tracks or if a car moves through a railroad crossing, according to the Association of American Railroads.

What other crashes may have been averted?

The NTSB has said PTC technology could have prevented numerous railroad accidents that involved human error.

The agency points to the 2013 Metro-North commuter train derailment in the Bronx, New York, in which four people were killed and dozens injured. The engineer fell asleep and failed to slow the train from more than 82 mph to the maximum authorized speed of 30 mph as it entered a curve, the NTSB said.

In 2015, an Amtrak train in Philadelphia derailed after it hit a curve at 106 mph in a 80-mph zone. The wreck killed eight people and injured more than 200 others. Sumwalt said then that the derailment would not have happened if PTC had been in place.

CNN’s Javier de Diego, Natasha Chen, Catherine E. Shoichet and Ray Sanchez contributed to this report.