The length of Historic Columbia River Highway tunnels in feet. (Library of Congress, Prints & Photographs Division, HAER ORE, 26-TROUT.V1- (sheet 16 of 27))
Oneonta Tunnel was built in 1914. (Library of Congress, Prints & Photographs Division, HAER ORE, 26-TROUT.V1- (sheet 16 of 27))
With the Historic Columbia River Highway hemmed in by tall basalt cliffs to the south and the railroad to the north, tunnels often provided the only practical alternative to longer and more costly alignments of the road. Because of this imperative, three tunnels were built along the highway between 1914 and 1921. While hailed as engineering masterpieces when constructed, the tunnels soon had trouble handling larger vehicles. The narrow tunnel widths, along with the real threat of rockfall, made the highway something of a hazardous adventure for travelers.
Oneonta Tunnel, constructed in 1914, was the first and shortest tunnel on the original highway. At the west approach, an 80-foot long slab bridge carried the road to the tunnel portal. Highway engineers saw an opportunity to realign the road to bypass the tunnel in 1948, after the railroad moved its right-of-way to water level. A new 48-foot deck girder bridge was built parallel to the old bridge and the tunnel was backfilled. The restored Oneonta Tunnel was opened to non-motorized traffic in 2009.
Mitchell Point Tunnel, completed in 1915, and Mosier Twin Tunnels, dating to 1921, saw similar fates. The iconic Mitchell Point Tunnel provided spectacular views of the Gorge through its five famous windows until the highway was relocated in the 1950s. Ultimately, the tunnel was completely destroyed in 1966. Planning for a new Mitchell Point Tunnel is currently underway. The Mosier Twin Tunnels, featuring two adits (side passages leading to windows) and a cliff walk, was backfilled by 1958. Restoration of the Mosier Twin Tunnels was completed in 2000.
Portals of the Mosier Twin Tunnels, built in 1921. Drawings on this page were based on original design documents, historical photographs and field measurements.
(Library of Congress, Prints & Photographs Division, HAER ORE, 26-TROUT.V1- (sheet 16 of 27))
Tooth Rock Tunnel
The construction of Bonneville Dam led to the realignment of the Historic Columbia River Highway with Tooth Rock Tunnel in 1937. Measuring 827 feet in length, it became the longest tunnel on the highway, and could safely handle larger vehicles with its 26-foot roadway. Other more modern engineering features, such as the lighting system and 4-foot wide sidewalks, served to set Tooth Rock Tunnel apart from the original tunnels on the highway. In order to allow the safe passage of even larger vehicles through the tunnel, its roadbed was lowered and its sidewalks were removed. The tunnel currently is used on the eastbound lanes of Interstate 84.
A drawing describing the west portal of the Tooth Rock Tunnel in 1937. (Library of Congress, Prints & Photographs Division, HAER ORE, 26-TROUT.V1- (sheet 16 of 27))
A drawing showing the 1915 Mitchell Point Tunnel.
(Library of Congress, Prints & Photographs Division, HAER ORE, 26-TROUT.V1- (sheet 16 of 27))
Historic and Current Tunnel Images
Cars travel west through the Mosier Twin Tunnels. (Oregon State Archives, Oregon State Highway Department Photographs)
A car passes another car as they leave the west end of the Oneonta Tunnel in 1916. (Oregon State Archives, Oregon State Highway Department Photographs)
Credit
Most of the information on this page was adapted from the Historic American Engineering Record, National Park Service, Pete Brooks, 1995. (Library of Congress, Prints & Photographs Division, HAER ORE, 26-TROUT.V1- (sheet
16 of 27))