Amtrak Cascades Train 501 was going more than twice the posted speed limit when it derailed at a sharp turn near DuPont, Washington, on December 18, 2107.

Federal investigators have interviewed the engineer who was at the controls of Amtrak Cascades Train 501 that derailed last month south of Tacoma. The interview summary points more strongly to human error as the cause of the deadly wreck.

The locomotive engineer told investigators from the National Transportation Safety Board that he knew a sharp curve was coming up, but as filtered through the NTSB, he said he “didn’t recall” seeing the advance speed limit sign.

The first of such warning signs is posted two miles before the curve in question.

When the engineer recognized looming danger, he testified he applied the brakes. But by then it was too late, just seconds before the speeding train launched off an overpass and crashed onto adjacent Interstate 5.

The derailment killed three passengers and injured more than 60 of those onboard along with an eight motorists whose vehicles crashed into derailed train carriages.

Numerous injured passengers and a driver on the freeway have since sued Amtrak. They allege inadequate crew training and negligence in not activating automatic speed control technology on the line.