Watch again: NTSB briefing on the deadly train derailment near Seattle

A worker walks along a damaged train car atop a flat bed trailer taken from the scene of Monday's fatal Amtrak train crash onto Interstate 5 Dec. 19, 2017, in DuPont, Wash. The Amtrak train that plunged off an overpass south of Seattle was hurtling 50 mph over the speed limit when it jumped the track, federal investigators said.   Elaine Thompson, AP

Cars from an Amtrak train lay spilled onto Interstate 5 below alongside smashed vehicles as some train cars remain on the tracks.  Elaine Thompson, AP

Cars from an Amtrak train lay spilled onto Interstate 5 below as some train cars remain on the tracks above Monday, Dec. 18, 2017, in DuPont, Wash.  Elaine Thompson, AP

National Transportation Safety Board Member Bella Dinh-Zarr, left, arrives for a news conference at the National Transportation Safety Board headquarters in Washington, Monday.  Andrew Harnik, AP

A handout photo made available by the Pierce County Sheriffs Department shows the trucks of Amtrak train 501 which derailed onto Interstate 5 near Tacoma, Washington.  Pierce County Sheriff

National Transportation Safety Board Member Bella Dinh-Zarr speaks at a news conference at the National Transportation Safety Board headquarters, Sunday.  Andrew Harnik, AP

Work crews survey the scene of an Amtrak train derailment in DuPont, Washington. At least three people were killed when a passenger train car plunged from the bridge. The derailment also closed southbound I-5.  Stephen Brashear, Getty Images

This image from video provided by KOMO-TV, shows the site of an Amtrak train that derailed south of Seattle on Monday, Dec. 18, 2017.   KOMO-TV, AP

A handout photo made available by the Pierce County Sheriffs Department showing Amtrak train 501.  Pierce County Sheriff, EPA-EFE

A handout photo made available by the Pierce County Sheriffs Department showing Amtrak train 501.  Pierce County Sheriff, EPA-EFE

A handout photo made available by the Pierce County Sheriffs Department showing Amtrak train 501 which derailed onto Interstate 5.  Pierce County Sheriff , EPA-EFE

A handout photo made available by the Pierce County Sheriffs Department showing Amtrak train 501 which derailed onto Interstate 5.  Pierce County Sheriff, EPA-EFE

A car covered in mud and debris and with a smashed windshield and other damage sits parked on the shoulder just beyond where an Amtrak train lay spilled onto Interstate 5 below as some train cars remain on the tracks above Monday, Dec. 18, 2017, in DuPont, Wash. The Amtrak train making the first-ever run along a faster new route hurtled off the overpass Monday near Tacoma and spilled some of its cars onto the highway below, killing some people, authorities said. Seventy-eight passengers and five crew members were aboard when the train moving at more than 80 mph derailed about 40 miles south of Seattle before 8 a.m., Amtrak said. (  Elaine Thompson, AP

This photo provided by Danae Orlob shows an Amtrak train that derailed south of Seattle on Monday, Dec. 18, 2017  Danae Orlob, AP

A handout photo from the Washington State Patrol shows Amtrak train 501, which derailed onto Interstate 5.  Washington State Patrol District 1

A train appears to have derailed near Olympia, Washington with part of the train on I-5 on Dec. 18, 2017.  WSDOT Tacoma Traffic