Exceeding railroad track speed limits by as little as five miles per hour could derail a train, according to an expert who used a simulator to show NBC News how to slow a locomotive ahead of a curve.
The demonstration came as investigators said the Amtrak train that crashed in north Philadelphia on Tuesday was accelerating when it derailed. It was hurtling at 106 mph — more than twice the 50 mph speed limit — at the time of the crash as it entered a curve, according to the National Transportation Safety Board.
At least eight people on Amtrak’s Northeast Regional Train 188 were killed and scores more of the 243 people on board were injured.
Engineer Brandon Bostian, 32, was expected to be interviewed by investigators in the coming days.
Training instructors used a simulator Thursday to show NBC News the importance of managing a train’s speed.
“The locomotive has got so much power that it will get away from you pretty easily so that’s why you’ve got to pay attention to what you’re doing,” said Chris Smutny of Modoc Railroad and Modoc Academy.
Slowing a train from 55 mph to 25 mph would take up to three-quarters of a mile, he added.
“You’ve got to slow down slowly otherwise you’re going to have a lot of in train forces and you can jack-knife the train,” he said.
"[On] a 25 mph curve… if we have to take that curve at, let’s say, 30 mph … even at 30 mph it will roll the train over.”
Modoc's president David Rangel believes the job is so demanding that there should always be more than just one engineer driving the train.
“We're just tired and that's what they're not saying," he said. "These guys are exhausted, they're overworked, and the job is just too much for one guy."
National Transportation Safety Board member Robert Sumwalt said Tuesday's crash wouldn't have happened if the curve had been along a stretch of track equipped with a working Positive Train Control system, which is supposed to be implemented on nearly all U.S. tracks that carry passengers or hazardous cargo by the end of the year.
While much of Amtrak's Northeast Corridor has been been upgraded and turned on, the stretch where Train 188 derailed isn't yet one of them.
Sumwalt and other NTSB officials have taken every opportunity since the derailment to call on lawmakers not to delay full implementation of the system — as has been requested by railroad lobbyists — at a time when rail funding is under attack in Congress.
