According to the National Transportation Safety Board, the Amtrak train that derailed in Philadelphia, killing at least seven people, was travelling at twice the speed limit.
The driver applied the emergency brakes when the train hit 106mph on a 50mph track, said the NTSB.
His efforts had only brought the speed down to 102mph when the deadly crash happened.
The speed was recorded in the so-called black box recovered from the wreckage.
He said: “We feel that had such a system been installed in this section of track, this accident would not have occurred.”
Amtrak Train 188 was going from Washington to New York when it derailed on May 12, leaving more 200 people injured.
The death toll rose from six to seven on May 13, as another body was found by the search and rescue team.
Only three victims have been publicly identified so far. Jim Gaines, a 48-year-old father of two and software architect for the Associated Press, was travelling home to New Jersey following a work conference in Washington DC. Justin Zemser, a-20 year-old Navy Midshipman, was on leave from the Naval Academy in Maryland, and was visiting family in New York. Wells Fargo senior vice-president Abid Gilani, the company confirmed.
One of the busiest stretches of passenger rail in the country, between Philadelphia and New York, is closed as officials continue to try to establish exactly what happened.
President Barack Obama said he was “shocked and deeply saddened to hear of the derailment”.
As emergency crews continued to dig through the wreckage, lawmakers in Washington debated the future of Amtrak’s budget, with one spending committee voting to slash their funding by almost a fifth.
Congress has only 18 more days before federal funding for transportation infrastructure expires, but the funding is likely to be temporarily extended.
Amtrak is a national publicly funded rail service, serving tens of millions of people every year.