(Adds more details from report, background)
WASHINGTON, Jan 4 (Reuters) - The damage from a deadly Amtrak train crash in Washington state in December topped $40.4 million, the U.S. National Transportation Safety Board said in a preliminary report on Thursday.
The safety board also said the crash that killed three and injured 70 could have been prevented if a safety technology system known as positive train control had been operational.
The board previously said Amtrak 501 was traveling at 78 miles per hour (126 km per hour) when it derailed, far above the 30 mph speed limit. The NTSB also said it has not been able to interview either operating crewmember due to their injuries from the accident.
The NTSB reported last month that six seconds before the derailment off a bridge and onto a highway, the engineer remarked that the train was speeding. The engineer then applied the brakes but apparently not the emergency brake, NTSB said.
U.S. Transportation Secretary Elaine Chao, in letters released on Tuesday, urged the nation's railroads and transit agencies to "take all possible measures" to meet congressional deadlines to install positive train control to prevent crashes.
Chao said she wanted railroads to "greatly accelerate" efforts to meet congressional deadlines.
Positive train control (PTC) is designed to prevent derailments caused by excessive speed. The NTSB has said several deadly U.S. train crashes in recent years could have been prevented if the system was in place and has for years urged its universal adoption.
In 2008, Congress mandated the implementation of PTC nationwide by the end of 2015, then extended that deadline until the end of 2018 when its installation became more complex than anticipated. The government can extend the deadline to 2020 to complete some aspects of the system.
Amtrak said last month it was "imperative that the rail industry urgently work together to get PTC activated on the national network as soon as possible - and certainly by the December 2018 federal deadline, if not before."
Washington state officials have said PTC was installed and being tested but was not yet been operational on the line where the derailment occurred. (Reporting by David Shepardson; Editing by Meredith Mazzilli)