BURLINGTON, Wash. - Nearly a year after an oversized load aboard a truck struck a curved beam that held up the I-5 bridge over the Skagit River on May 23, there are no plans or money to modify scores of other bridges with a similar design used widely on steel truss bridges on both four lane interstates and two lane crossings in the 1950s.
The collapsed span of the Skagit River bridge, which was built in 1955, was replaced with a concrete structure. The remaining steel trusses had their upper beams squared off to a height of 18-feet. But scores of other bridges from the two lane bridge on SR 9 just upstream or bridges, like the I-5 bridge over the Nooksack River at Ferndale, are very similar if not identical to what the I-5 bridge over the Skagit used to look like.
They are among the bridges known as being "fracture critical," meaning even with the design change, the bridges lack what engineers call redundant load paths, meaning the loss of a single key structural member doesn't cause the entire structure to fail.
An investigation by the Washington State Patrol into the Canadian trucking company and its driver accused of hitting the bridge and triggering the collapse is still open and no tickets have yet been issued.
The National Transportation Safety Board considers the collapse to be a major investigation. The federal agency is expected to issue its final report along with the probable cause of the accident along with recommendations to prevent future accidents mid-summer, likely July, according to a spokesman.