The Federal Railroad Administration announced it has instructed Amtrak to ensure that Automatic Train Control is in use on both northbound and southbound tracks; to assess risk at all curves and make any needed speed control adjustments; and increase the number of signs showing maximum authorized speed.
"These are just initial steps, but we believe they will immediately improve safety for passengers on the Northeast Corridor," Acting Federal Railroad Administrator Sarah Feinberg said.
"While we do not yet know everything that happened, we do know -- without question -- that protecting rail passengers is our top priority," Foxx said. "The actions we have instructed Amtrak to take are aimed at improving safety on this corridor immediately, but we won't hesitate to require the railroad to do more to improve safety as the accident's causes become clearer."
A conductor on the train that derailed outside of Philadelphia on Tuesday told investigators that she remembers hearing the train's engineer "say something about his train being struck by something" to a different train's engineer.
The Amtrak engineer, identified earlier this week as Brandon Bastion, met with NTSB investigators Friday and he was "extremely cooperative," NTSB board member Robert Sumwalt said.
Bastion told investigators that the last thing he remembered happening before the crash was ringing the train bell as he passed through the North Philadelphia train stop. He did not mention anything about his alleged radio conversation with a local Philadelphia train engineer.
It was determined that the train accelerated more than 35 mph in the final 65 seconds before the crash, the NTSB announced Thursday. The train's forward facing camera recorded the speed but investigators were not able to determine why it was accelerating at that point or if the engineer was actively raising the speed.