SEATTLE—The collapse of an interstate highway bridge in northern Washington state should be a wake-up call that prompts an expansive safety review, according to National Transportation Safety Board officials.
Investigators are trying to determine why a bridge over Interstate 5—about 60 miles (100 kilometres) north of Seattle and leading to the fourth-busiest Canada-US border crossing—collapsed after a truck clipped a steel truss.
Officials are also deciding what can be done to prevent similar accidents.
NTSB Chairwoman Debbie Hersman examined the scene in the Skagit River where two vehicles plunged into the water. Three people involved escaped with non-life threatening injuries.
An investigation by The Associated Press suggests similar accidents could happen elsewhere. Thousands of bridges around the U.S. are kept standing by engineering design, rather than sheer size or redundant protections. Such spans may be one freak accident or mistake away from collapse.
Bridge regulators call them “fracture critical” bridges, because if a single, vital component is compromised, they can crumple.
Hersman’s team will spend about a week inspecting the I-5 bridge, talking to the truck driver whose vehicle is alleged to have hit it and examining maintenance documents and accident reports.
Other large vehicles struck the Skagit River bridge before the collapse Thursday, she noted. Investigators are using a high tech 3-D video camera to review the scene and attempt to pinpoint where the bridge failure began. Officials say they are working to find out whether the collapse was a fluke or a sign of bigger problems.
State and federal officials will work together on the investigation, she said.
They’ll be watching for safety issues that could affect other bridges.
Washington state officials said it will take time to find both short- and long-term fixes for the I-5 bridge.
While the NTSB finishes its inspection, state workers will begin cleaning up the river. Next, a temporary solution will be put in place to return traffic to Washington state’s most important north-south roadway.
The section of I-5 between Mount Vernon and Burlington will be closed for many weeks and possibly months, said Washington Transportation Department spokesman Bart Treece.
About 71,000 vehicles use that stretch of highway every day.
Officials were looking for a temporary, pre-fabricated bridge to replace the 160-foot (48-meter) section that failed, Washington Gov. Jay Inslee said Friday. That option could be in place in weeks. Otherwise, it could be months before a replacement can be built, the governor said.
Inslee said it will cost $15 million to repair the bridge.