Timber braced tunnel
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GN - Horseshoe Tunnel (King County, Washington)
Built 1893 bypassed 1929 collapsed on unknown dateLost TunnelCollapsed
Mosier Twin Tunnels (Wasco County, Oregon)
Built 1920, Closed due to rock fall problems 1953, Reopened to public in 2000Tunnel under Mosier Tunnel on Historical Columbia River Highway TrailOpen to pedestrians
Oneonta Tunnel (Multnomah County, Oregon)
Built 1914, Bypassed and Sealed 1948 , Re-Opened to pedestrians 2009; timber lining destroyed by wildfire Sept. 2017Tunnel under Oneonta Basalt Out-Cropping on Historical Columbia River HighwayRe-Opened to pedestrians in 2009; damaged by fire Sept. 2017