According to the Washington Department of Transportation, a first-of-its-kind culvert has helped the WSDOT to reopen State Route 203 just south of Duvall late Sunday, Aug. 30, much more quickly than traditional methods would have allowed.
The project replaced a culvert that, at times, was too slow and alternately to high, that carries Loutsis Creek under the highway to improve passage for native and migratory fish. The new culvert will allow Coho salmon, steelhead, and cutthroat trout to use an additional 3.5 miles of spawning and rearing habitat.
Contractors working for WSDOT installed the culvert – built with fiberglass arches filled with concrete – and finished rebuilding the highway over Loutsis Creek in five weeks. This is the first use of the system on the West Coast and for the agency, which helped shorten the time it usually takes to replace a culvert more than 40 feet under a highway. The original project was slated to take much longer.
“This approach requires less heavy equipment and can be done much more quickly than work that uses heavy concrete girders,” said WSDOT Project Engineer Shawn Wendt. “We have hundreds of culverts to replace in the next 10 years. This was a pilot project for WSDOT. We will evaluate it and determine if we may be able to use it for other projects.”
Using traditional construction methods, it could take two to three months to dig up and replace a culvert 30 to 50 feet underneath a roadway. Working with the lighter fiberglass dramatically reduces that time. The hollow 50-foot long, 1-foot diameter fiberglass tube, built by AIT Bridges in Maine, only weighs about 500 pounds. That means a few people can move an arch, and it takes only light equipment to place it, instead of the massive cranes a traditional concrete girder would require.
The crews from Goodfellow Brothers excavated more than 2,000 dump truck loads from the site, and the 12 arches were placed in less than a day, then filled with concrete. Plates placed across the arches completed the structure. After waiting a few days for the concrete to harden, crews filled in the dirt over and around the bridge, then repaved the road.
AIT Bridges and the University of Maine cooperated in the development of composite arches about 10 years ago. This type of structure has been used mostly on the East Coast since then.
With the early completion of this project, SR 203 is now a detour route for a King County project on West Snoqualmie Valley Road. Because that was the detour route for WSDOT’s SR 203 project, King County timed its month-long project until work on the highway at Loutsis Creek was finished.
People traveling on SR 203 near Duvall should plan for additional traffic during the West Snoqualmie Valley Road closure.