Positive train control, or PTC, can automatically slow and halt a train if it detects that the locomotive is travelling too fast or is in danger of collapsing. The technology has been dubbed the “single-most important rail safety development in more than a century” by the Federal Railroad Administration.

Several people were hurt after an Amtrak train derailed in Missouri, according to the passenger rail operator.

Also read: Amtrak Missouri crash: 5 deadliest derailments

According to the company, the train collided with a dump truck at a public crossing in the city of Mendon at around 1:42 pm CT.

“There are approximately 243 passengers onboard with early reports of injuries,” company officials revealed. “Local authorities are currently assisting customers and we have deployed Amtrak resources to assist.”

How does PTC operate?

It’s a system that uses GPS, wireless radio, and computers to keep trains from colliding, derailing, or speeding.

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

According to rail safety experts, PTC was supposed to prevent the human errors that cause approximately 40% of train accidents by ensuring that it is run in line with signals, speed limits, and other rules. It’s a track and train system that works together.

Also read: Amtrak train derails a day after fatal crash: All you need to know

If a train engineer doesn’t detect a curve or a location 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 had told CNN.

For decades, the NTSB has advocated for the implementation of PTC. 

Could PTC have stopped this train derailment?

T. Bella Dinh-Zarr, an NTSB board member, has stated that PTC does not ensure complete safety.

“We should remember that PTC can’t prevent every accident,” she stated. “It does prevent certain types of derailments, overspeed accidents as well as incursions into work zones, for example.”

Also read: How Amtrak train derailed in Mendon, Missouri, eyewitness accounts and more

As per the Association of American Railroads, PTC cannot prevent accidents if there is trespassing on the tracks or a car drives through a railroad crossing.

What other accidents may have been avoided?

According to the NTSB, PTC technology could have averted countless railroad incidents caused by human error.

The agency cites the 2013 Metro-North passenger train derailment in the Bronx, New York, which killed four people and injured hundreds more. According to the NTSB, the operator fell asleep and was unsuccessful to slow the train from more than 82 mph to the maximum permissible speed of 30 mph as it reached a curve.

Also read: Amtrak crash: History of train accidents from vehicle collisions

In 2015, an Amtrak train derailed in Philadelphia after hitting a bend at 106 mph in an 80-mph zone. The crash killed eight people and injured almost 200 more. Sumwalt stated at the time that if PTC had been in place, the derailment would not have occurred.