Oneonta Tunnel

Photos 

Oneonta Tunnel

from the east

Photo taken by Michael Goff on June 14, 2009

Enlarge

Map 

Street Views 

Facts 

Overview

Tunnel under Oneonta Basalt Out-Cropping on Historical Columbia River Highway

Location

Multnomah County, Oregon

Status

Re-Opened to pedestrians in 2009

History

1914 Built, 1948 Bypassed and Sealed, 2009 Re-Opened

Builders

- S.P. White & Co. (Contractor)
- Samuel Lancaster (Lead Engineer)

Design

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.)

Dimensions

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)

USGS topographic map

Multnomah Falls

Inventory number

BH 38486 (Bridgehunter.com ID)

Categories 

Update Log 

• 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

Sources 

• Mike Goff - michael [dot] goff [at] hotmail [dot] com
• Oneonta Tunnel - - Historic Columbia River Highway
• Friends of the Historic Columbia River Highway
• Oneonta Re-Opening - "The Oregonian" Video about the re-opening of Oneonta Tunne

Comments