Federal safety officials say the technology known as positive train control would probably have prevented the Dec. 1 train derailment that killed four people in New York.
The National Transportation Safety Board says the system would have required the engineer to slow the train to an appropriate speed. If he failed to do so, the technology would have stopped the train, "likely preventing the derailment."
The board has said the train was traveling at 82 mph entering a curve with a speed limit of 30 mph.
The board had previously said it was possible that positive train control would have prevented the crash.
The engineer's lawyer has said he may have experienced a momentary loss of awareness at the controls.
Railroads face a congressional deadline to install the technology by December 2015.
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