NTSB Press Release

National Transportation Safety Board
Office of Public Affairs

NTSB Issues Second Investigative Update on I-5 Bridge Collapse in Washington

May 31

The National Transportation Safety Board today released a second update in its continuing investigation into the May 23 bridge collapse in Mount Vernon, Washington.

The accident truck and trailer, the exemplar truck and trailer, and the pick-up truck that was on the bridge when it collapsed have all been released. Investigators will be downloading the airbag module from the Subaru (the other vehicle on the bridge during the collapse) to determine if it might contain any information relevant to the investigation.

Both the driver of the pickup truck and the driver of the Subaru have been interviewed. Interviews with other witnesses to the accident are ongoing.

Regarding the collapsed section of the bridge, all of the steel structure above the water line has been removed. NTSB investigators are documenting the entire collapsed bridge structure as the Washington Department of Transportation officials work to remove the remaining bridge elements from the river. Investigators will continue documentation efforts as WDOT removes the collapsed bridge deck (road surface) and substructure from the water, which is expected to continue into next week.

An NTSB investigator traveled to the headquarters of Mullen Trucking in Alberta, Canada, to gather information on the motor carrier’s operations, safety history, training process, maintenance procedures and records, and other documents related to the investigation.

In a media briefing near the accident site on May 25, the NTSB said that Washington State does not require vertical clearance signage to be posted unless the clearance is fourteen feet four inches or less. Further research indicated that the actual minimum vertical clearance over the travel lanes requiring signage is fifteen feet three inches or less. In either reference, the Skagit River Bridge measures greater than fifteen feet three inches over the travel lanes and therefore does not require signage.

This is an informational release only. No interviews will be conducted.

Further investigative updates will be issued as warranted.

Office of Public Affairs
490 L'Enfant Plaza, SW
Washington, DC 20594
(202) 314-6100
Peter Knudson



The National Transportation Safety Board (NTSB) is an independent federal agency charged with determining the probable cause
of transportation accidents, promoting transportation safety, and assisting victims of transportation accidents and their families.