This is a list of tunnels built in the city of Seattle, Washington, USA.

The Puget Sound region, where Seattle lies, has a history of glaciation that has left many hills and ridges that civil engineers have needed to traverse for transportation and utilities.[1] Some of these tunnels are part of megaprojects.

Tunnels

Year(s) Constructed Tunnel Diameter Length Notes References
1894 Lake Union Sewer Tunnel 72 in (1.8 m) 5,736 ft (1,748 m) Hand excavated [1]
1894 South Bayview Street Tunnel 4 ft (1.2 m) x 6 ft (1.8 m) 4,526 ft (1,380 m) Hand excavated [1]
1903–1905 Great Northern Tunnel 38 ft (12 m) 5,141 ft (1,567 m) Hand excavated [1]
1907 Oregon and Washington Railroad Tunnel 38 ft (12 m) 900 ft (270 m) Hand excavated; never completed (filled in 1922) [1]
1910 First Avenue Utilidor Tunnel 8 ft (2.4 m) 300 ft (91 m) Compressed air, hand [1]
1910 4th and Connecticut Ave. Sewer 3–6 ft (0.91–1.83 m) 7,060 ft (2,150 m) Supported trench [1]
1910 Ravenna Sewer Tunnel 80 in (2.0 m)
Relined 66 in (1.7 m) 		2,875 ft (876 m) Hand; tried tunnel boring machine [1]
Early 1900s Wallingford Tunnel 9 ft (2.7 m) 1,803 ft (550 m) Open cut and tunnel [1]
Early 1900s Pacific Street Tunnel 9 ft (2.7 m) 11,325 ft (3,452 m) Open cut and tunnel [1]
1910 Lander Street Sewer 4.5–9 ft (1.4–2.7 m) 5,290 ft (1,610 m) Supported trench [1]
1911 Fort Lawton Tunnel 10 ft (3.0 m) 9,720 ft (2,960 m) Hand dug [1]
1911 Montlake Siphon Tunnel 4 ft (1.2 m) 2,005 ft (611 m) Hand dug [1]
1912 Dexter and 8th Avenue Tunnel 5 ft (1.5 m) 9,315 ft (2,839 m) Hand dug [1]
1912 Washington Park Tunnels 5 ft (1.5 m) 4,052 ft (1,235 m) Hand dug [1]
1913 Third Avenue West Siphon Tunnel 21 ft (6.4 m) 500 ft (150 m) Hand dug [1]
1926 Jackson Street Drainage Tunnel 4 ft × 6 ft (1.2 m × 1.8 m) 1,500 feet (460 m) Hand dug
35 psi compressed air 		[1]
1930 South Hanford Street Tunnel 9 ft (2.7 m) 6,055 ft (1,846 m) Hand dug [1]
1931 Charleston Street Tunnel 3.5 ft (1.1 m) 2,830 ft (860 m) [1]
1936 Henderson Trunk Sewer Tunnel 60 in (1.5 m) (I.D., concrete)
48 in (1.2 m) (brick) 		3,000 ft (910 m) Hand dug
Concrete and brick 		[1]
1936 Laurelhurst Trunk Sewer Tunnel 9 ft (2.7 m) 1,850 ft (560 m) [1]
1938–1941 Mount Baker Tunnel 28 ft × 23 ft (8.5 m × 7.0 m) 1,330 ft (410 m) [1]
1934–1942 WPA slide control drainage projects 4 ft × 6 ft (1.2 m × 1.8 m) 4,926 ft (1,501 m) [1]
1952–1954 Battery Street Tunnel 3,140 ft (960 m) Originally named Battery Street Subway [2][3]
1963 Montlake Siphon Tunnel replacements 42 in × 108 in (1.1 m × 2.7 m) 586 ft (179 m) [1]
1965–1966 Elliott Bay Interceptor section 6 tunnel 8 ft × 12.5 ft (2.4 m × 3.8 m) 1,750 feet (530 m) Tunnelling shield [1]
1964–1967 Lake City Sewer Tunnel 8 ft × 11 ft (2.4 m × 3.4 m) 17,570 feet (5,360 m) Close-face wheel excavator [1]
1967–1968 Second Avenue Sewer Tunnel 8.5 ft × 12.5 ft (2.6 m × 3.8 m) 19,900 feet (6,100 m) Tunnelling shield [1]
1960s to present University of Washington utilidors Various, 5–10 ft (1.5–3.0 m) 50,000 feet (15,000 m) total [1][4]
1975 Northwest Kidney Center pedestrian tunnel 10 ft (3.0 m) horseshoe 120 ft (37 m) Bobcat loader [1]
1983–1986 Mount Baker Tunnel expansion 65 ft (20 m) 1,330 ft (410 m) Tunnelling shield
World's largest diameter soil tunnel 		[1]
1984 Seattle Public Utilities Beacon Hill Waterline/Cedar River Pipeline 12 ft (3.7 m) 150 ft (46 m) [1]
1985 Columbia Center pedestrian tunnel 14 ft (4.3 m) horseshoe 280 ft (85 m) [1]
1985 Virginia Mason Hospital pedestrian tunnel 10 ft (3.0 m) horseshoe 120 ft (37 m) Bobcat loader [1]
1986 Renton Sewer Tunnel ETS-4A 12 ft (3.7 m) O.D. 2,403 ft (732 m) Drill and shoot [1]
1986 Renton Sewer Tunnel ETS-4B 12 ft (3.7 m) O.D. 620 ft (190 m) Drill and shoot [1]
1986 Renton Sewer Tunnel ETS-5 12 ft (3.7 m) O.D. 1,820 ft (550 m) Drill and shoot [1]
1986 Renton Sewer Tunnel ETS-6 12 ft (3.7 m) O.D. 1,056 ft (322 m) First use of Earth Pressure Balance Machine in Seattle [1]
1987–1988 Downtown Seattle Transit Tunnel Twin 21.25 ft (6.48 m) 13,624 ft (4,153 m) Tunnelling shield
First use of waterproofing PVC membrane in USA 		[1]
1990 Fort Lawton Tunnel/West Point Sewer 15.5 ft (4.7 m) O.D. 8,400 feet (2,600 m) Partial Earth Pressure Balance Machine [1][5]
1993 Royal Brougham Street Sewer Tunnel 10 ft (3.0 m) O.D. 300 ft (91 m) [1]
1993 Lake Washington Canal Tunnel 3.3 ft (1.0 m) 1,518 ft (463 m) First slurry microtunnel in Seattle [1]
1995 Lander Street Sewer Tunnel 10 ft (3.0 m) O.D. 130 ft (40 m) [1]
1995 First Avenue Utilidor Tunnel 10 ft (3.0 m) 500 ft (150 m) Microtunnel [1]
1995–1997 West Seattle Sewer Tunnel 13 ft (4.0 m) 10,500 feet (3,200 m) Partial Earth Pressure Balance Machine
Maximum 400 feet (120 m) below surface 		[1][5]
1997 Eastlake Storm Sewer Tunnel 3.5 ft (1.1 m) 475 ft (145 m) Slurry microtunnel [1]
2001 Justice Center Tunnel 15 ft (4.6 m) horseshoe 200 ft (61 m) [1]
2002 Denny CSO Storage Tunnel 16.8 ft (5.1 m) O.D. 6,212 ft (1,893 m) First complete Earth Pressure Balance Machine tunnel in Seattle [1][5][6]
2002 Henderson CSO Storage Tunnel 16.8 ft (5.1 m) O.D. 3,105 ft (946 m) Earth Pressure Balance Machine, connecting microtunnels [1][5]
2006 Beacon Hill tunnel Twin 20 ft (6.1 m) 1 mi (1.6 km) Tunnel boring machine [7]
2009–2012 University Link Tunnel Twin 20 ft (6.1 m) 3 mi (4.8 km) Tunnel boring machine
$1.9 billion megaproject 		[8][9]
2007–2011 Brightwater Sewage Tunnel 17.5 ft (5.3 m) 13 mi (21 km) Four tunnel boring machines
Maximum depth 400 feet (120 m)
Part of $1.8 billion megaproject 		[5][10][11][12]
2013–2018 Alaskan Way Viaduct replacement tunnel 57 feet (17 m) 2 mi (3.2 km) $4.25 billion megaproject
World's largest tunnel boring machine, 57.5 feet (17.5 m) in diameter 		[13]
2014–2016 Northgate Link tunnel Twin 20 ft (6.1 m) 3.4 mi (5.5 km) Tunnel boring machine
$2.1 billion megaproject 		[14]
2019– King County Ship Canal Water Quality Project 21.67 ft (6.61 m) and 8 ft (2.4 m) 2.7 mi (4.3 km) Largest tunnel boring machine named "Mudhoney" to construct combined sewer outflow storage tunnel under EPA consent decree. Two smaller machines for conveyance tunnels. [15][16]

See also

Further reading

References

  1. ^ a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab ac ad ae af ag ah ai aj ak al am an ao ap aq ar as at au av Robert A. Robinson; Edward Cox; Martin Dirks, Tunneling in Seattle: A History of Innovation, North American Tunnelling Conference, Seattle, Wash., 2002, retrieved 2012-12-16
  2. ^ Bridges and roadway structures, Seattle Department of Transportation, retrieved 2012-12-17
  3. ^ Phil Dougherty (April 1, 2007), "Final phase of Seattle's Alaskan Way Viaduct opens to traffic on September 3, 1959", HistoryLink, Seattle: History Ink
  4. ^ Jenny Hansson (September 27, 1995), "The freedom to have a tunnel map", UW Daily, retrieved 2012-12-16
  5. ^ a b c d e 2010 Brightwater Project Progress and Tunneling Status (PDF), King County Waste Treament Division
  6. ^ Featured Project: Denny Way CSO Control Project, American Underground Construction Association, retrieved 2012-12-16
  7. ^ Mike Lindblom (April 21, 2006), Beacon Hill tunneling a breeze, The Seattle Times
  8. ^ Scott Gutierrez (May 15, 2012), Light rail tunnels now link downtown to Capitol Hill, UW, Seattle Post-Intelligencer
  9. ^ "University Link Extension". Sound Transit. Archived from the original on 2012-10-14. Retrieved 2012-12-15.
  10. ^ Jack Broom (September 8, 2009). "2 tunneling machines on Brightwater sewer project are damaged — and 300 feet deep". The Seattle Times. Retrieved 2012-12-15.
  11. ^ Scott Gutierez (August 17, 2011). "Brightwater tunneling completed this week". Seattle P-I. Retrieved 2012-12-15.
  12. ^ Jeff Switzer (September 25, 2007), "Machine moves 100 trucks of dirt a day", Everett Herald
  13. ^ Alaskan Way Viaduct replacement program: Tunneling, Washington State Department of Transportation, retrieved 2012-12-17
  14. ^ "Sound Transit contractor completes mining last tunnel segment for Northgate Link Extension" (Press release). Sound Transit. September 2, 2016. Retrieved September 10, 2016.
  15. ^ Tim Newcomb (April 19, 2021), "Seattle's Latest Tunnel Boring Machine Will Dig 2.7 Miles", Engineering News-Record
  16. ^ "Meet our tunnel boring machines". Ship Canal Water Quality Project. Retrieved March 3, 2022.
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