Flathead Tunnel

The Flathead Tunnel is a 7-mile-long (11 km) railroad tunnel in the Rocky Mountains of northwest Montana near Trego, approximately 28 miles (45 km) west of Whitefish. Located on the BNSF Railway's Kootenai River Subdivision, it is the second-longest railroad tunnel in the United States after the Cascade Tunnel.[1][2] It is ultimately named after the Bitterroot Salish, also known as the Flathead.

Flathead Tunnel
Eastbound Empire Builder enters Flathead Tunnel
Overview
LineKootenai River Subdivision (Northern Transcon)
LocationLincoln County, Montana, USA
Coordinates48°33′03″N 114°57′22″W
SystemBNSF
Operation
Work begunMay 12, 1966[1]: 2 
Constructedblasted with cut and cover portals
OpenedNovember 7, 1970
OwnerBNSF Railway
Traffic40 trains daily (as of 2022)
Technical
Length36,955 ft (7.0 mi; 11.3 km)[1]: 2 
No. of tracksSingle
Track gauge4 ft 8+1⁄2 in (1,435 mm) standard gauge
Highest elevation3,720 ft (1,130 m)
Lowest elevation3,620 ft (1,100 m)

The tunnel was constructed for the Great Northern Railway by the Walsh Construction Company and S.J. Groves and Sons (collectively known as Walsh–Groves) at a cost of nearly $44 million (equivalent to $285 million in 2021).[3] It is part of a 60-mile (97 km) rerouting of the Great Northern Hi-Line that became a necessity due to construction of Libby Dam and subsequent creation of Lake Koocanusa.[1][4]

Work began on May 12, 1966.[3] Drilling was completed on June 21, 1968 when President Lyndon B. Johnson ceremoniously triggered a final explosion from a circuit connected via telephone to the White House.[5][6]

Finishing work continued for the following two years, and the tunnel, along with the entire rerouted rail line it is a part of, opened on November 1, 1970. An opening ceremony was held on November 7, 1970 and included the passage of the first official train through the tunnel, a 21-car passenger special carrying 1,200 area residents who were offered the opportunity to travel a circular route from Libby and back on both the new and old rail lines.[7][8]

Official records indicate that two people were killed in two separate incidents during construction, both occurring after drilling was complete.[3][6]

As of 2022 the tunnel is used by about 40 freight trains each day as well as Amtrak's Empire Builder.[9] Maximum speed through the tunnel is 50 miles per hour (80 km/h).[10] The north portal contains a ventilation system to clear the tunnel of diesel locomotive exhaust and provide cooling air to eastbound locomotives, as there is an uphill grade heading eastbound.[11][9]

References
  1. The Flathead Tunnel: A Geologic, Operations, and Ground Support Study, Burlington Northern Railroad, Salish Mountains, Montana (PDF). University of North Texas Library (Report). Spokane Mining Research Center. U.S. Bureau of Mines. 1974. Retrieved 2 August 2021.
  2. Franz, Justin (13 February 2018). "BNSF to Improve Flathead Tunnel as Part of Annual Capital Program". Flathead Beacon. Retrieved 12 October 2018.
  3. Weber, Jeremy (January 16, 2022). "Trego railroad tunnel major construction feat". Kalispell, Montana: Daily Inter Lake. Archived from the original on May 19, 2022. Retrieved February 20, 2023.
  4. Floyd, Doug (August 25, 1975). "Dam gets Ford's praise, but it's not energy key". Spokane Daily Chronicle. (Washington). pp. 1, 3.
  5. "President Presses Button". Havre Daily News. Havre, Montana. June 24, 1968. p. 11.
  6. Weber, Jeremy (May 22, 2022). "Stories from Trego tunnel deviate from historical record". Kalispell, Montana: Daily Inter Lake. Archived from the original on May 22, 2022. Retrieved February 20, 2023.
  7. "Railroad News Photos". Trains. Kalmbach Publications. February 1971. p. 12.
  8. "Fine Train Program". Daily Inter Lake. Kalispell, Montana. November 13, 1970. p. 4.
  9. Weber, Jeremy (January 16, 2022). "'Tunnel rats' and an engineering marvel". Kalispell, Montana: Daily Inter Lake. Archived from the original on May 19, 2022. Retrieved February 20, 2023.
  10. Kelly, Bruce. "FLATHEAD TUNNEL AT 50". Trains. No. February 2021. Kalmbach. pp. 30–33.
  11. "Tunnel Test Functions Well". Daily Inter Lake. Kalispell, Montana. October 1, 1970. p. 1.


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