from the east
Photo taken by Michael Goff on June 14, 2009
BH Photo #141517
- Tunnel under Oneonta Basalt Out-Cropping on Historical Columbia River Highway
- Multnomah County, Oregon
- Re-Opened to pedestrians in 2009; damaged by fire Sept. 2017
- Built 1914, Bypassed and Sealed 1948 , Re-Opened to pedestrians 2009; timber lining destroyed by wildfire Sept. 2017
- - S.P. White & Co. (Contractor)
- Samuel Lancaster (Lead Engineer)
- The Oneonta Tunnel consisted of a 125' straight bore through a 200' tall outcropping of Columbia River basalt. It measured 20' wide with a vertical clearance of just over 19' (a radius of 9'-10" measured at 9'-2-1/2" from the floor). No written records document Oneonta tunnels construction chronology, but extensive information is available on how contractors bored Mitchell Point Tunnel and the Mosier Twin Tunnels also on the Historic Columbia River Highway.
At Oneonta, S. P. White Company most likely began work early in 1914. The material was Columbia River basalt: with frequent cleavage places, and commonly known as ''dice'' rock, because it broke up unto small fragments when it was blasted. The heading, or top portion of the bore was taken out first, followed by the bench. Blasting crews used extreme care when working near the outside wall. Because of natural conditions: they could only retain an 18' wall. Rock formations contained many large fissures. According to historian Oral Bullard, "The problem at the Oneonta Tunnel Was that in order to prevent thousands of tons of rocks from cascading down into the railroad tracks when the blasting began it was necessary to go to considerable extra work to strengthen the cliff before digging into it." Lancaster devised a plan whereby White's crews injected concrete into crevasses in an attempt to stabilize the material.
(Excerpted from Historic American Engineering Record, Oneonta Tunnel, HAER 0R-OR-36-L.)
Span length: 125.0 ft.
Total length: 125.0 ft.
Deck width: 20.0 ft.
Vertical clearance above deck: 19.0 ft.
- Approximate latitude, longitude
- +45.58944, -122.07528 (decimal degrees)
45°35'22" N, 122°04'31" W (degrees°minutes'seconds")
- Approximate UTM coordinates
- 10/572131/5048849 (zone/easting/northing)
- Quadrangle map:
- Multnomah Falls
- Inventory numbers
- HAER 0R-OR-36-L
BH 38486 (Bridgehunter.com ID)
- September 7, 2017: Updated by Alexander D. Mitchell IV: Tunnel's timber lining destroyed by wildfire Sept. 6, 2017:
- September 8, 2010: New Street View added by Michael Goff
- June 15, 2009: Updated by Michael Goff
- April 20, 2009: Updated by Michael Goff
- January 6, 2009: Added by Michael Goff