Formerly carried the Historic Columbia River Highway, Multnomah Country, Oregon, through a rock outcropping immediately east of the mouth of Oneonta Gorge, beginning east of milepost 34.3.
Date of Construction
Samuel Lancaster, Consulting Engineer for Multnomah County and Assistant State Highway Engineer, Oregon State Highway Department
S. P. White and Co., Vancouver, Washington, contractor
Oregon Department of Transportation
None; closed in 1948. NOTE: Tunnel reopened to pedestrian traffic March 21, 2009. Automobile traffic (historic vehicles only) is permitted during special events.
One of four tunnels on the Historic Columbia River Highway.
The Historic Columbia River Highway’s alignment from Crown Point, milepost 23.9, to Horsetail Falls Bridge, milepost 34.6, takes the highway along one of the largest concentrations of high waterfalls in North America. Near its eastern end lies Oneonta Creek and Gorge. The name ”Oneonta,” according to Oregon Geographic Names originates in Oneonta, New York, and means “place of peace”. The Oregon Steam Navigation Company ran a sidewheeler named Oneonta on the Columbia, above and below its cascades, in the 1860s and 187Os. Oneonta Creek and Gorge probably were named sometime after the boat’s construction.
In 1914, the Multnomah County Road Department and Samuel Lancaster sought to align the route so that it brought travelers to the mouth of Oneonta Gorge, a canyon so narrow that its basalt walls almost touch as they rise two hundred feet above the creek. Subsequently, the county built Oneonta Gorge Creek Bridge. Carrying the alignment past a nearby 200′ bluff, a continuation of the Oneonta Gorge, proved more difficult. In the 1880s the Oregon-Washington Railroad and Navigation Company (OWRN) had laid out its route along the Columbia River’s south shore. Much or it was along the old Troutdale to The Dalles road begun in the 1870s. The OWRN’s right-of-way crossed Oneonta Gorge Creek then passed through a narrow opening between the river and the bluff before continuing east. With the close proximity of the river and the cliff, there was no additional space to permit carrying the HCRH around the outcropping.
Determined to include Oneonta Gorge and nearby Horsetail Falls as two of the natural beauty spots on the HCRH’s route, Lancaster resolved this dilemma by having a tunnel bored through the outcropping.
Plans stipulated creating an alignment that included a bridge over Oneonta Gorge Creek parallel and to the south of the railway span, and continuing east through the rock wall via a 125′ tunnel. The Multnomah County Road Department called for bids in late 1913, and by the end of the year it had received contract proposals from 12 firms. Of these, S. P. White and company of Vancouver, Washington, had the low bid of $30.00 per linear foot of excavation on the tunnel, with a 75 ¢ per cubic yard charge for enlargement. White’s construction engineer, G. M. Pitts, had widespread construction experience on the West coast and in the Intermountain regions of the United Staten. He had operated machinery in 1899-1900 on a tunnel for the Great Northern Railway, was concrete foreman in 1901-02 for the Montana Central Railway’s Wicks Tunnel, in 1903-04 for the Great Northern’s Tunnel under Seattle, and in 1909-10 for the Milwaukee Railroad. He had most recently worked with the Pacific Bridge Company, which received contracts to construct many of the bridges built along the Multnomah County portion of the HCRH.
Design and Desription
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.
Cutting Oneonta Tunnel was a tedious process that involved the skill of an experienced explosives expert. The arrangement of blast holes, and the sequence of explosions, most likely using 40 percent dynamite and black powder, were the key to precise boring. At Mitchell Point, construction engineer John Arthur Elliott wrote that to ensure that crews did not collapse the outside wall,
The lower outside lift hole was dropped one round back, leaving each time about 3′ of the heading next to the thin wall, thus increasing the effective thickness of the outer wall. This lift hole was always one round behind until all danger of breaking out had been passed…The firing order was controlled by varying the length of the fuses. shorter fuses were used in the center, and cut holes and longer fuses in the lift holes. In this Way, the center section was broken before the heavier charges in the lift holes exploded, which made the work of the lift holes easier. By holding the outside lift hole back one round, the necessity of breaking to a wall on both sides was eliminated, and the explosives broke out along diagonal lines converging towards the powder charges, which also made the heading easier to break.
At Mitchell Point, the contractor limited hole depth in the heading to 4′. Crews used 11/2 sticks of 40 percent dynamite to spring each hole, followed by a per hole charge of 16 to 20 sticks of the dynamite. Each explosive round moved the bore along about 4-1/2′
After detonating the charges, crews loaded the heading material into ore cars on tracks and dumped the material out the portals. Crews trimmed the roof with picks and hammers after each shot, and then pilled or stripped off the bench. They used two sticks of 40 percent dynamite to spring each hole and followed this with loads of 18 to 22 sticks. Crews loaded, or mucked out, the bench material in the came manner as the heading, dumping it out the portals.
A photograph dated April 25, 1914 showing dozens of onlookers at Oneonta tunnels west portal also marks the progress of crews lining the tunnel with lumber sets and lagging. Samuel Lancaster wrote Multnomah County Roadmaster John B. Yeon in March 1914, urging construction of a lining for the tunnel because of frost action on the porous and seamed rock at Oneonta and ever present moisture. He worried about the safety of motorists who might receive serious Injuries from falling rock inside the tunnel. In the 1910s and 1920s, most motorists would be vulnerable even inside their automobiles because most vehicles used soft collapsible tops.
The S. P. White Company completed the Oneonta Tunnel during 1914 at a cost of $6,684.88. This included $4,140.00 for cutting the tunnel, $523.05 for excavating the portals, and $1,723.29 for 61,546 board feet of timbering. The tunnel, however, was not immediately opened to traffic. The Construction Company of Portland did not complete an 80′ reinforced-concrete deck girder bridge over Oneonta Gorge Creek near the tunnels west portal until later in the year.
Repair and Maintenance
The Oneonta Tunnel served on the Historic Columbia River Highway from 1914 until 1948 when a highway realignment bypassed it. Maintenance records for the tunnel do not survive, but drawings from 1931 suggest that it was relined that year, most likely because the original timber sets and lagging had rotted from moisture penetration. A comparison of lining plans for Oneonta Tunnel and plans for the 1920-21 lining of the Mosier Twin Tunnels shows striking similarities. The new lining was probably a replication of the original construction. It consisted of 12″ x 12″ timber sets spaced 4′-0″ on centers for the heading portion and 6″ x 16″ sets on 4′-0″ centers for the vertical walls riding on 12″ x 12″ sills. The lagging consisted of 4″ x 6″ Douglas Fir boards laid horizontally. Up the vertical walls rode four 2″ x 12″ timber guard rails, spaced 18″ on centers, and running the tunnels length. Four 10″ x 12″ sets placed vertically at 1″ spacing and four pairs of at least 12″ x 12″ stacked timbers placed horizontally above them formed the tunnel portals (an additional, or third timber was stacked above the outside-most set of headers). Finally, timber inclined endposts finished the wooden portion of the portals. A dry masonry wall dating from the tunnel’s original construction, framed the wood. The 1931 plans called for extending the bottom two plank guard rails outside the portals at a 450 angle, running about 4′ to connect with 12″ x 12″ posts as a continuation of standardized post and plank guard fences. These were never constructed.
Oneonta tunnels lining reduced its clear dimensions. Its roadway width became 16′-9″. Horizontal clearance at the curb line was about 10′ and 16′ at the centerline. By the mid-1930s, with greatly increased traffic volume, and larger vehicles, Oneonta tunnels vertical and horizontal clearances were too small to safely accommodate two-way traffic. In July 1936, the Oregon State Highway Department installed traffic activated one- way stop-and-go signals at the tunnel portals, temporarily solving the traffic safety problems. The department also installed similar signals at Mitchell Point Tunnel in 1938 and at the Mosier Twin Tunnels in the 1940s.
Rock fall due to frost was a continual problem at Oneonta Tunnel. Chunks of basalt filled the cavity between the tunnel bore and the lining and dropped on the roadway at the portals. The greatest concern was the perennial covering of the OWRN (later Union Pacific Railroad) main line with rock tumbling off the cliff. Not only did it often close the track to traffic, it cumulatively weakened the outer tunnel wall, threatening eventual collapse and possibly burying the main line for an extended period. The Union Pacific also worried about a disastrous rock fall and track closure if one of its large articulated steam locomotives happened to derail near Oneonta Tunnel and slam into the cliff.
In 1948 the railroad saw an opportunity to end its Worries about the tunnel by moving its trackage north of the cliff on fill dredged from the Columbia. This created room for the highway department to re-route the HCRH around the cliff on the old railroad right-of-way. The state then mothballed the tunnel with fill to prevent continuous raveling and possible collapse. The highway department constructed a new bridge, on the old railroad span’s original piers as part of the realignment, and retained the old bridge and adjacent abandoned roadway as a parking area for travelers to Oneonta Gorge. In the subsequent four decades, vegetation has completely overtaken the Oneonta Tunnel portals, leaving many a person to ask why the old Oneonta Gorge Creek span is a bridge to nowhere.
Excerpted from Historic American Engineering Record, Oneonta Tunnel, HAER 0R-OR-36-L.
Historian: Robert W. Hadlow, Phd., September 1995.
Transmitted by: Lisa M. Pfueller, September, 1996.