(PIX11) -- The Amtrak train that derailed in Philadelphia Tuesday night was traveling at more than 106 mph, more than twice as fast as the speed limit for the curve it was trying to negotiate, before the engineer hit the brakes, the National Transportation Safety Board said.
The accident was also preventable had a certain technology been in place, said NTSB member Robert Sumwalt in a news conference. The accident killed seven people and injured at least 200 others.
The NTSB revealed Friday afternoon that 11 minutes into the trip, at 9:21 p.m., as the train made a left turn, the whole train derailed. The train had just been placed into "engineer-induced braking," When the brake was applied, the train was going 106 mph, and 3 seconds later, that speed had only decreased slightly, to 102 miles per, according to preliminary data. The engineer should have entered the curve at no more than 50 mph.
There was no technology that could have automatically slowed the train. The NTSB said that had a system called Advanced Civil Speed Enforcement been in place -- as it is in other areas of the Northeast Corridor -- Tuesday night would have ended differently.
"We feel that had such a system been installed in this section of track, this accident would not have occurred," he told reporters.
The train, bound for New York's Penn Station, had one locomotive and seven passenger cars, with 243 people onboard, including five crew members. The engineer has not yet been interviewed.
"We do not know what happened here," Mayor Michael Nutter said. "We do not know why it happened."
Amtrak's Northeast Corridor, which runs between Washington, D.C., and Boston, is North America's busiest railroad, with 11.6 million riders in fiscal year 2014. Every day, trains reaching speeds between 125 mph and 150 mph carry government officials, college students, people getting away for the weekend and corporate commuters along 363 miles of track.
Nutter said the train's recorder was recovered Wednesday and sent to an Amtrak facility in Delaware, where its data is being downloaded. Information about that data could be made available later Wednesday, according to Sumwalt.
In general terms, however, when it comes to speed, Amtrak's Northeast corrider trains, "when (they) get into the flat, straight-out areas of Maryland, can go over 100 miles an hour," according to transportation expert Matthew Wald. "But in Philadelphia, the track is older, there are more curves, generally it is going slower."
The speed limit in the area of the crash is around 50 mph, according to the official with knowledge of the investigation. But passenger Janna D'Ambrisi said she thought the train was going "a little too fast around a curve."
Investigators will also consider the condition of the track. There are roughly 880,000 miles of rail track in the United States, according to Mary Schiavo, a former inspector general for the U.S. Department of Transportation and a CNN analyst, and a lot of it is in less-than-ideal shape. In Philadelphia, however, along the bustling northeast corridor, the situation is perhaps more dire.
"It's an extremely heavily used stretch of track," Wald said of the area. "They have trouble keeping it in a state of good repair."
Nutter told reporters the train's engineer was injured in the crash, but has been able to speak to officials. It's too early to determine if the engineer played any role here, but some recent rail accidents have been blamed on human error.
New York commuter train engineer William Rockefeller Jr. admitted falling asleep before derailing in a 2013 Bronx crash that left four dead and 67 injured, and investigators found that a 2009 trolley crash in Boston that injured more than 60 occurred because the operator was texting his girlfriend.
CNN contributed to this report.