List of tunnels in Seattle

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 Year(s) ConstructedTunnelDiameterLengthNotesReferences1894Lake Union Sewer TunnelHand excavated1894South Bayview Street TunnelHand excavated1903–1905Great Northern TunnelHand excavated1907Oregon and Washington Railroad TunnelHand excavated; never completed (filled in 1922)1910First Avenue Utilidor TunnelCompressed air, hand19104th and Connecticut Ave. SewerSupported trench1910Ravenna Sewer TunnelRelined Hand; tried tunnel boring machineWallingford TunnelOpen cut and tunnelPacific Street TunnelOpen cut and tunnel1910Lander Street SewerSupported trench1911Fort Lawton TunnelHand dug1911Montlake Siphon TunnelHand dug1912Dexter and 8th Avenue TunnelHand dug1912Washington Park TunnelsHand dug1913Third Avenue West Siphon TunnelHand dug1926Jackson Street Drainage TunnelHand dug35 psi compressed air1930South Hanford Street TunnelHand dug1931Charleston Street Tunnel1936Henderson Trunk Sewer Tunnel (I.D., concrete) (brick)Hand dugConcrete and brick1936Laurelhurst Trunk Sewer Tunnel1938–1941Mount Baker Tunnel1934–1942WPA slide control drainage projects1952–1954Battery Street TunnelOriginally named Battery Street Subway1963Montlake Siphon Tunnel replacements1965–1966Elliott Bay Interceptor section 6 tunnelTunnelling shield1964–1967Lake City Sewer TunnelClose-face wheel excavator1967–1968Second Avenue Sewer TunnelTunnelling shield1960s to presentUniversity of Washington utilidors total1975Northwest Kidney Center pedestrian tunnel horseshoeBobcat loader1983–1986Mount Baker Tunnel expansionTunnelling shieldWorld's largest diameter soil tunnel1984Seattle Public Utilities Beacon Hill Waterline/Cedar River Pipeline1985Columbia Center pedestrian tunnel horseshoe1985Virginia Mason Hospital pedestrian tunnelBobcat loader1986Renton Sewer Tunnel ETS-4ADrill and shoot1986Renton Sewer Tunnel ETS-4BDrill and shoot1986Renton Sewer Tunnel ETS-5Drill and shoot1986Renton Sewer Tunnel ETS-6First use of Earth Pressure Balance Machine in Seattle1987–1988Downtown Seattle Transit TunnelTunnelling shieldFirst use of waterproofing PVC membrane in USA1990Fort Lawton Tunnel/West Point SewerPartial Earth Pressure Balance Machine1993Royal Brougham Street Sewer Tunnel1993Lake Washington Canal TunnelFirst slurry microtunnel in Seattle1995Lander Street Sewer Tunnel1995First Avenue Utilidor TunnelMicrotunnel1995–1997West Seattle Sewer TunnelPartial Earth Pressure Balance MachineMaximum below surface1997Eastlake Storm Sewer TunnelSlurry microtunnel2001Justice Center Tunnel2002Denny CSO Storage TunnelFirst complete Earth Pressure Balance Machine tunnel in Seattle2002Henderson CSO Storage TunnelEarth Pressure Balance Machine, connecting microtunnels2006Beacon Hill tunnelTunnel boring machine2009–2012University Link TunnelTunnel boring machine$1.9 billion megaproject2007–2011Brightwater Sewage TunnelFour tunnel boring machinesMaximum depth Part of $1.8 billion megaproject2013–2018Alaskan Way Viaduct replacement tunnel$4.25 billion megaprojectWorld's largest tunnel boring machine, in diameter2014–2016Northgate Link tunnelTunnel boring machine$2.1 billion megaproject2019–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.

See also List of tunnels in the United States

Further reading

References