No votes cast

UP - Natron Cutoff Tunnel 23


West Portal Of Tunnel 23, Contextual View To The West-Northwest, 380mm Lens. Tunnel 22 Pierces The Toe Of Lookout Point. Note That The Tracks Have Been Realigned Toward The Willamette River To Bypass Tunnel 23

Photo taken for the Historic American Engineering Record

View photos at Library of Congress

BH Photo #301050



The Southern Pacific Railroad Cascade Route, built as the Natron Cutoff between Black Butte, California and Natron, Oregon was one of a series of major rebuildings and realignments of the original Central Pacific Railroad. Begun in 1905 under railroad magnate E.H. Harriman to replace the original Central Pacific route over the Siskiyou Mountains into Oregon, the Natron Cutoff had to overcome both natural and political obstacles. Stalled by government anti-trust lawsuits against Harriman, by World War I and the ensuing federal takeover of the nation's railroads, the Natron Cutoff finally overcame the rugged Cascade Mountains of Oregon to reach completion in 1927, at an ultimate cost of nearly $40 million. For the purpose of the current project, the Natron Cutoff was found likely to be eligible for the National Register of Historic Places at the state level of significance under Criterion A for its significance in engineering, transportation history, and the economic history of central Oregon, and in the development of the West, and under criterion B for its association with E.H. Harriamn. The Natron Cutoff's period of significance is 1905 to 1945, from the beginning of construction in 1905, through the years of its role in the economic development of the central Oregon, to the conclusion of the railroad's achievements in World War II. Built in 1910, Tunnel 23 is a contributive element of this property.

Tunnel 23 is a 654-foot, single track railroad tunnel with concrete portal faces and wingwalls. The semi-circular arched opening is framed in dressed stone masonry voussoirs, the portal has a concrete parapet atop a stone masonry belt course topped by dressed stone masonry coping. A coping of dressed stone masonry blocks tops the stepped wingwalls. As-built, the tunnel was concrete-lined for the first fifty feet in from each portal, with the remainder unlined; because of continual creel of the slope which the tunnel pierced, the railroad subsequently lined the bore with timber bents in 1931, 1951, and 1953, and has since covered the timbering with shotcrete. The tunnel is on a tangent (no curve) alignment, and carried the tracks of the Union Pacific Railroad's (formerly Southern Pacific) Cascade Route line until its recent abandonment.

-- Historic American Engineering Record


Abandoned tunnel
Lane County, Oregon
Built 1923; closed late1980's
- Utah Construction Co. of Ogden, Utah
- Southern Pacific Railroad (SP)
- Union Pacific Railroad (UP)
Total length: 654.0 ft.
Approximate latitude, longitude
+43.76258, -122.52564   (decimal degrees)
43°45'45" N, 122°31'32" W   (degrees°minutes'seconds")
Approximate UTM coordinates
10/538182/4845613 (zone/easting/northing)
Quadrangle map:
Westfir West
Inventory number
BH 63573 (Bridgehunter.com ID)

Update Log 

  • October 12, 2014: Added by Dave King


  • Dave King - DKinghawkfan [at] hotmail [dot] com
  • HAER OR-95 - Southern Pacific Railroad Natron Cutoff, Tunnel 23, Milepost 584.5, Westfir, Lane County, OR