Individuals working on the Amtrak train that derailed in Washington state last month cautioned their superiors that they were not appropriately trained to operate the new route, according to a CNN investigation published Sunday.
The report cited worries among employees tasked with operating the train, with several sources telling the news outlet that training was "totally inadequate.”
Sources also told CNN that some of the training was conducted at night and involved six or more workers jammed into three-seat cars.
The speeding train derailed on its inaugural run while traveling across a highway overpass in December, killing three people.
The crash spurred an investigation by the National Transportation Safety Board (NTSB), which said last week in an update on the probe that the engineer missed an advance speed sign prior to the crash. The report also found that the engineer misidentified a signal at the 19.8-mile mark for a separate signal.
“He said that as soon as he saw the 30 mph sign at the start of the curve, he applied brakes,” the NTSB said of the engineer. “Seconds later, the train derailed as it entered the curve.”
But the engineer also told the NTSB, which interviewed both the engineer and the conductor, that he would not have operated the train had he not felt prepared.
“The engineer also said that he would not have gotten behind the throttle if he had any reservations about his readiness to operate the train,” the safety board said.
Amtrak directed CNN to the NTSB when questioned about allegations of insufficient training.
"Our highest priority is ensuring the safety of our passengers, our crew and the communities we serve,” Amtrak told the news network in its own statement.
“We are actively taking measures to strengthen the safety of our operations, from adopting a safety management system approach used by commercial aviation to advancing Positive Train Control across the network. We will continue to work with the NTSB to learn from this accident and improve."
The NTSB said in its update last week that it expects the probe into the crash to last between 12 and 24 months.
The safety agency also found in a preliminary report issued earlier this month that a key train safety feature known as Positive Train Control (PTC), which automatically decreases the speed of a train traveling over the limit, would have slowed down the train.
The crash pushed House Democrats to introduce legislation that would give railroads until the end of the year to enact PTC. That bill would also prevent the Department of Transportation from giving extensions to railroads attempting to delay meeting the PTC implementation deadline.