SR 20, Red Cabin Creek Bridge in East Skagit County

Crews have completed the Red Cabin Creek project between Lyman and Hamilton. The new bridge replaces a culvert, and allows water and debris to flow naturally under the highway.

Each winter heavy rain storms would cause Red Cabin Creek to rise and it would bring sediment and debris downstream which would plug the culvert beneath SR 20.

Water flowing across the highway was not only a safety hazard for motorists, but the plugged culvert was a chronic problem for WSDOT Maintenance crews and spawning salmon.

 

In the Spring of 2011, construction of a new bridge over Red Cabin Creek began. A temporary detour allowed construction of the new bridge on the existing alignment. Sheet piling was installed so that a concrete seal could be placed and then the new bridge piers constructed in the dry. The concrete seals were approximately 9’ thick and 15’ to 20’ below the bottom of the creek channel.

The new bridge was designed using ten 68’ long voided slab girders with a 5” cast in place concrete bridge deck. Using the voided slab girders reduced the depth of the new bridge, which helped reduce the length of SR 20 that needed to be raised to the provide more clearance between SR 20 and the creek.

The new bridge was completed in the fall of 2011 eliminating closures of SR 20 due to flooding and enhancing fish habitat.

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