NTSB Press Release
National Transportation Safety Board
Office of Public Affairs
NTSB Issues an Investigative Update on the Interstate 5 Bridge Collapse in Washington
The National Transportation Safety Board today released an update on its investigation into the May 23 bridge collapse in Mount Vernon, Washington. A 160-foot span of the four-lane Interstate 5 bridge collapsed into the Skagit River.
Witnesses reported that just prior to the collapse, a truck tractor in combination with an oversized semitrailer, traveling southbound on I-5, struck the overhead truss superstructure.
NTSB investigators have been on scene since the night the bridge collapsed and are continuing to coordinate activities with the Washington Department of Transportation.
- NTSB investigators are scheduled to interview the driver of the pilot car tomorrow.
- Both vehicles and the camper trailer that plunged into river when the bridge collapsed have been removed from the water and the vehicles are being inspected by an NTSB survival factors expert. Investigators hope to gain impact forces data from the air bag modules on each of the vehicles.
- Several bridge structural span frames on the west side of the structure, including span U-4, of significant interest to the NTSB, were removed from the water yesterday. Today, span U-4 on the east side will be removed. Once removed, all of the spans will be inspected, in the field, by an NTSB metallurgist who will determine if sections need to be shipped to our laboratory in Washington, D.C. for further inspection.
- Measurements of the accident truck and trailer and load are still being verified. In addition, a mechanical inspection of the accident truck found one flaw that would have put the truck out of service, but did not contribute to the accident.
- Investigators have received several surveillance videos of the accident sequence and are reviewing them.
- Investigators are continuing to interview additional witnesses of the accident.
- Work on scene will continue for several more days.
This is an informational release only. No interviews are being conducted.
Further investigative updates will be issued as events warrant. To be alerted to any updates or developments, please follow the NTSB on Twitter at twitter.com/ntsb.
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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.