List of tunnels in Seattle explained

This is a list of tunnels built in the city of Seattle, in the U.S. state of Washington.

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. Some of these tunnels are part of megaprojects.

Tunnels

data-sort-type="number"Year(s) Constructed!Tunneldata-sort-type="number"Diameter!data-sort-type="number"Length!NotesReferences
1894Lake Union Sewer Tunnel5736feetHand excavated
1894South Bayview Street Tunnel4526feetHand excavated
1903–1905Great Northern Tunnel5141feetHand excavated
1907Oregon and Washington Railroad Tunnel900feetHand excavated; never completed (filled in 1922)
1910First Avenue Utilidor Tunnel300feetCompressed air, hand
19104th and Connecticut Ave. Sewer7060feetSupported trench
1910Ravenna Sewer Tunnel
Relined 66inches		2875feetHand; tried tunnel boring machine
Wallingford Tunnel1803feetOpen cut and tunnel
Pacific Street Tunnel11325feetOpen cut and tunnel
1910Lander Street Sewer4.5-5290feetSupported trench
1911Fort Lawton Tunnel9720feetHand dug
1911Montlake Siphon Tunnel2005feetHand dug
1912Dexter and 8th Avenue Tunnel9315feetHand dug
1912Washington Park Tunnels4052feetHand dug
1913Third Avenue West Siphon Tunnel500feetHand dug
1926Jackson Street Drainage Tunnel1500feetHand dug
35 psi compressed air
1930South Hanford Street Tunnel6055feetHand dug
1931Charleston Street Tunnel2830feet
1936Henderson Trunk Sewer Tunnel (I.D., concrete)
48inches (brick)		3000feetHand dug
Concrete and brick
1936Laurelhurst Trunk Sewer Tunnel1850feet
1938–1941Mount Baker Tunnel1330feet
1934–1942WPA slide control drainage projects4926feet
1952–1954Battery Street Tunnel3140feetOriginally named Battery Street Subway
1963Montlake Siphon Tunnel replacements586feet
1965–1966Elliott Bay Interceptor section 6 tunnel1750feetTunnelling shield
1964–1967Lake City Sewer Tunnel17570feetClose-face wheel excavator
1967–1968Second Avenue Sewer Tunnel19900feetTunnelling shield
1960s to presentUniversity of Washington utilidors50000feet total
1975Northwest Kidney Center pedestrian tunnel horseshoe120feetBobcat loader
1983–1986Mount Baker Tunnel expansion1330feetTunnelling shield
World's largest diameter soil tunnel
1984Seattle Public Utilities Beacon Hill Waterline/Cedar River Pipeline150feet
1985Columbia Center pedestrian tunnel14feet horseshoe280feet
1985Virginia Mason Hospital pedestrian tunnel120feetBobcat loader
1986Renton Sewer Tunnel ETS-4A2403feetDrill and shoot
1986Renton Sewer Tunnel ETS-4B620feetDrill and shoot
1986Renton Sewer Tunnel ETS-51820feetDrill and shoot
1986Renton Sewer Tunnel ETS-61056feetFirst use of Earth Pressure Balance Machine in Seattle
1987–1988Downtown Seattle Transit Tunnel13624feetTunnelling shield
First use of waterproofing PVC membrane in USA
1990Fort Lawton Tunnel/West Point Sewer8400feetPartial Earth Pressure Balance Machine
1993Royal Brougham Street Sewer Tunnel300feet
1993Lake Washington Canal Tunnel1518feetFirst slurry microtunnel in Seattle
1995Lander Street Sewer Tunnel130feet
1995First Avenue Utilidor Tunnel500feetMicrotunnel
1995–1997West Seattle Sewer Tunnel10500feetPartial Earth Pressure Balance Machine
Maximum 400feet below surface
1997Eastlake Storm Sewer Tunnel475feetSlurry microtunnel
2001Justice Center Tunnel200feet
2002Denny CSO Storage Tunnel6212feetFirst complete Earth Pressure Balance Machine tunnel in Seattle
2002Henderson CSO Storage Tunnel3105feetEarth Pressure Balance Machine, connecting microtunnels
2006Beacon Hill tunnelTunnel boring machine
2009–2012University Link TunnelTunnel boring machine
$1.9 billion megaproject		[1]
2007–2011Brightwater Sewage TunnelFour tunnel boring machines
Maximum depth 400feet
Part of $1.8 billion megaproject		[2] [3]
2013–2018Alaskan Way Viaduct replacement tunnel$4.25 billion megaproject
World's largest tunnel boring machine, 57.5feet in diameter
2014–2016Northgate Link tunnelTunnel boring machine
$2.1 billion megaproject		[4]
2019–King County Ship Canal Water Quality ProjectLargest tunnel boring machine named "Mudhoney" to construct combined sewer outflow storage tunnel under EPA consent decree. Two smaller machines for conveyance tunnels.[5]

See also

Notes and References

  1. Web site: University Link Extension. Sound Transit. 2012-12-15. https://web.archive.org/web/20121014023007/http://projects.soundtransit.org/Projects-Home/University-Link.xml. 2012-10-14. dead.
  2. News: Jack Broom. 2 tunneling machines on Brightwater sewer project are damaged — and 300 feet deep. The Seattle Times. September 8, 2009. 2012-12-15.
  3. News: Brightwater tunneling completed this week. Scott Gutierez. Seattle P-I. August 17, 2011. 2012-12-15.
  4. September 2, 2016 . Sound Transit contractor completes mining last tunnel segment for Northgate Link Extension . . September 10, 2016.
  5. Web site: Ship Canal Water Quality Project. Meet our tunnel boring machines. March 3, 2022.

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