US investigators into the New Jersey train crash in Hoboken at the end of September that killed one person and injured more than 100 others say the train was travelling at twice the legal speed when the accident took place.

The NJ Transit train slammed into the end of the platform in the historic Beaux Arts terminus, through the barrier and skidded across the station concourse, bringing down parts of the roof.

Engineer Thomas Gallagher, a 29-year railway veteran,10 as a driver, escaped with minor injuries and is helping with the inquiry. Excessive speed was determined as the cause of a 2011 accident at the same station, injuring more than 30 people.

He maintains his last memory is checking the speed and finding it correct before regaining consciousness after the crash.