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. [1] Some of these tunnels are part of megaprojects.
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] |
State Route 99 (SR 99), also known as the Pacific Highway, is a state highway in the Seattle metropolitan area, part of the U.S. state of Washington. It runs 49 miles (79 km) from Fife to Everett, passing through the cities of Federal Way, SeaTac, Seattle, Shoreline, and Lynnwood. The route primarily follows arterial streets, including Aurora Avenue, and has several freeway segments, including the tolled SR 99 Tunnel in Downtown Seattle. SR 99 was officially named the William P. Stewart Memorial Highway by the state legislature in 2016, after a campaign to replace an unofficial moniker honoring Confederate president Jefferson Davis.
The Alaskan Way Viaduct was an elevated freeway in Seattle, Washington, United States, that carried a section of State Route 99. The double-decked freeway ran north–south along the city's waterfront for 2.2 miles (3.5 km), east of Alaskan Way and Elliott Bay, and traveled between the West Seattle Freeway in SoDo and the Battery Street Tunnel in Belltown.
The Downtown Seattle Transit Tunnel (DSTT), also referred to as the Metro Bus Tunnel, is a 1.3-mile-long (2.1 km) pair of public transit tunnels in Seattle, Washington, United States. The double-track tunnel and its four stations serve Link light rail trains on the 1 Line as it travels through Downtown Seattle. It runs west under Pine Street from 9th Avenue to 3rd Avenue, and south under 3rd Avenue to South Jackson Street. 1 Line trains continue north from the tunnel to Northgate station and south through the Rainier Valley past Seattle–Tacoma International Airport to Angle Lake station as part of Sound Transit's light rail network.
State Route 519 (SR 519) is a state highway in Seattle, Washington, United States. It connects Interstate 90 (I-90) to the Port of Seattle and Colman Dock, which serves as the terminus of two ferry routes. The highway travels along city streets, including two named for Seattle Mariners personalities: Edgar Martinez Drive and Dave Niehaus Way, as well as Alaskan Way. SR 519 was established in 1991 on preexisting streets that were first built in the early 20th century. State projects moved the southern terminus of SR 519 in 2010 to its current location and temporarily rerouted it during demolition of the Alaskan Way Viaduct.
The Waterfront Streetcar, officially the George Benson Waterfront Streetcar Line, was a heritage streetcar line run by King County Metro in Seattle, Washington, United States. It traveled for 1.6-mile (2.6 km) along Alaskan Way on the city's waterfront facing Elliott Bay, under the Alaskan Way Viaduct. The Waterfront Streetcar used a fleet of five W2 trams from Melbourne, Australia.
Transportation in Seattle is largely focused on the automobile like many other cities in western North America; however, the city is just old enough for its layout to reflect the age when railways and trolleys predominated. These older modes of transportation were made for a relatively well-defined downtown area and strong neighborhoods at the end of several former streetcar lines, now mostly bus lines.
The 1 Line, formerly Central Link, is a light rail line in Seattle, Washington, United States, and part of Sound Transit's Link light rail system. It serves 19 stations in the cities of Seattle, SeaTac, and Tukwila, traveling nearly 25 miles (40 km) between Northgate and Angle Lake stations. The line connects the University District, Downtown Seattle, the Rainier Valley, and Seattle–Tacoma International Airport. The 1 Line carried over 26 million total passengers in 2023, with an average of nearly 80,000 daily passengers on weekdays. It runs for 20 hours per day on weekdays and Saturdays, with headways as low as six minutes during peak hours, and reduced 18-hour service on Sundays and holidays.
The Northgate Link tunnel is a light rail tunnel in Seattle, Washington, United States. The twin-bore Link light rail tunnel, built as part of the Northgate Link extension, carries a section of the 1 Line and connects the University District to Northgate.
Beacon Hill station is a light rail station located in Seattle, Washington. It is situated between the Mount Baker and SODO stations on the 1 Line, which runs from Seattle–Tacoma International Airport to Downtown Seattle and the University of Washington as part of the Link light rail system. The station is located 160 feet (49 m) under the southeast corner of Beacon Avenue South and South Lander Street in Seattle's Beacon Hill neighborhood.
SODO station is a light rail station located in Seattle, Washington. It is situated between the Beacon Hill and Stadium stations on the 1 Line, which runs from Seattle–Tacoma International Airport to Downtown Seattle and the University of Washington as part of the Link light rail system. The station consists of two at-grade side platforms at the intersection of the SODO Busway and South Lander Street in the SoDo neighborhood of Seattle.
The State Route 99 tunnel, also known as the Alaskan Way Viaduct replacement tunnel, is a bored highway tunnel in the city of Seattle, Washington, United States. The 2-mile (3.2 km), double-decker tunnel carries a section of State Route 99 (SR 99) under Downtown Seattle from SoDo in the south to South Lake Union in the north.
University of Washington station is a light rail station on the University of Washington campus in Seattle, Washington, United States. The station is served by the 1 Line of Sound Transit's Link light rail system, which connects Northgate, Downtown Seattle, and Seattle–Tacoma International Airport. University of Washington station is at the intersection of Montlake Boulevard Northeast and Northeast Pacific Street, adjacent to Husky Stadium and the University of Washington Medical Center.
Capitol Hill station is a light rail station in the Capitol Hill neighborhood of Seattle, Washington, United States. The station is served by Sound Transit's Link light rail system and is located near the intersection of Broadway and East John Street. It is situated between the Westlake and University of Washington stations on the 1 Line. The station consists of an island platform approximately 65 feet (20 m) under street level, connected to three surface entrances via two mezzanines. It contains pieces of public art, including Mike Ross's sculpture Jet Kiss and two murals by cartoonist Ellen Forney.
U District station is a light rail station on the 1 Line of Sound Transit's Link light rail system in Seattle, Washington, United States. It is located in the University District neighborhood, near the University of Washington campus. The underground station has two entrances along Brooklyn Avenue Northeast at 43rd and 45th streets.
Roosevelt station is a light rail station located in the Roosevelt neighborhood of Seattle, Washington, United States. It is served by the 1 Line of Sound Transit's Link light rail system, which continues north to Northgate station and south to Downtown Seattle and SeaTac. The underground station consists of a single island platform connected to the surface via a mezzanine and two entrances along 12th Avenue Northeast at Northeast 65th and 67th streets.
Brightwater is a regional sewage treatment plant in south Snohomish County, Washington, United States. It serves parts of the Seattle metropolitan area and was opened in 2011. The plant construction and associated tunneling were a five-year megaproject costing $1.8 billion.
The University Link tunnel is a 3.15-mile (5.07 km) light rail tunnel in Seattle, Washington. The twin-bore tunnel carries Link light rail service on the University Link Extension of Central Link, running from the Downtown Seattle Transit Tunnel to University of Washington station via Capitol Hill station. The 21 ft-wide (6.4 m) tunnels are lined with precast gasketed concrete segments connected with steel bolts and was excavated using three tunnel-boring machines in 2011 and 2012. Light rail service began on March 19, 2016.
Bertha was a 57.5-foot-diameter (17.5 m) tunnel boring machine built specifically for the Washington State Department of Transportation's (WSDOT) Alaskan Way Viaduct replacement tunnel project in Seattle, Washington, United States. It was made by Hitachi Zosen Sakai Works in Osaka, Japan, and the machine's assembly was completed in Seattle in June 2013. Tunnel boring began on July 30, 2013, with the machine originally scheduled to complete the tunnel in December 2015.
The SODO Busway, also referred to as the E-3 Busway, is a 1.5-mile-long (2.4 km) busway in the SoDo neighborhood of Seattle, Washington. It has four stops, including two that connect to Link light rail stations, and functions as an extension of the Downtown Seattle Transit Tunnel, which was formerly used by buses. The busway is served by ten bus routes—seven King County Metro routes from southern King County and three Sound Transit Express routes from Pierce County.