From sinkhole to smooth ride: SR 411 near Castle Rock reopens

New culvert restores safe travel and improves water flow under the roadway

CASTLE ROCK - Travelers can once again drive the full length of State Route 411, also known as West Side Highway, near Castle Rock in Cowlitz County.

On Friday, Oct. 24, Washington State Department of Transportation contractor, Tapani, Inc., finished emergency work to replace a failing culvert and reopen SR 411 to traffic.

Work began Monday, Sept. 8, when crews closed the highway to replace the aging culvert near Waters Road at milepost 9.55. Maintenance crews discovered the problem last spring while clearing drains after heavy rain. The culvert had reached the end of its life, causing flooding and a 15-foot sinkhole that made the road unsafe for travel.

"Replacing this culvert was critical for both driver and environmental safety," said WSDOT Project Engineer Jennette Queen. "With the new culvert in place, the road is fully restored, and water can flow safely through the new structure for years to come."

All lanes of SR 411 between mileposts 6.1 and 11.3 are now open to all vehicles, and weight restrictions have been lifted, allowing freight trucks and heavier vehicles to use the highway again.

Culverts are key to keeping both roads and streams healthy. The new 14-foot culvert carries water and fish safely under the road, helping prevent flooding and sinkholes and protecting the pavement above.

WSDOT appreciates the community's patience during the closure while repairs were underway.