State Route 99 tunnel

{{short description|Highway tunnel in Seattle, Washington}} {{Use American English|date=May 2025}} {{Use mdy dates|date=December 2019}} {{Infobox tunnel |name = SR 99 tunnel |image = WA-WSDOT-SR99-HD.jpg |image_size = |caption = A visualization of the tunnel |location = Seattle, Washington, U.S. |coordinates = {{coord|47|36|37|N|122|20|41|W|format=dms|display=inline|type:landmark_region:US-WA}} |mapframe-custom = {{maplink|frame=yes|plain=yes|frame-align=center|frame-width=250|frame-height=300|frame-lat=47.608|frame-long=-122.340|zoom=13|type=line|raw={{Wikipedia:Map data/Wikipedia KML/Alaskan Way Viaduct replacement tunnel}}}} |mapframe-caption = Route of the tunnel, highlighted in red |route = {{jct|state=WA|SR|99}} |status = Open |start = South Dearborn Street<br />{{coord|47.596534|-122.335699|format=dms|display=inline|name=South portal SR 99 tunnel|type:landmark_region:US-WA}} |end = Harrison Street<br />{{coord|47.620520|-122.344674|format=dms|display=inline|name=North portal SR 99 tunnel|type:landmark_region:US-WA}} |startwork = {{start date|2013|07|30}}<ref name=KN13 /> |opened = {{start date|2019|2|4}} |close = |owner = |operator = Washington State Department of Transportation |traffic = |character = |toll = $1.20 to $4.70 |vpd =  |construction = 2013–2017 |length = {{convert|9,270|ft|m mi}}<ref name="tunneling">{{Cite web |url=http://www.wsdot.wa.gov/Projects/Viaduct/About/Tunneling |title=Tunneling toward a new SR 99; The SR 99 tunnel route (map) |publisher=Washington State Department of Transportation |access-date=December 8, 2012 |archive-url=https://web.archive.org/web/20121210035623/http://www.wsdot.wa.gov/Projects/Viaduct/About/Tunneling |archive-date=December 10, 2012 |url-status=live }}</ref><ref>{{cite web |title=Follow Bertha |url=http://www.wsdot.wa.gov/Projects/Viaduct/About/FollowBertha |publisher=Washington State Department of Transportation |access-date=December 25, 2018}}</ref> |lanes = 4 |speed = {{convert|45|mph|kph|abbr=on}} |hielevation =  |lowelevation =  |height = {{convert|15|ft|9|in|m|1|abbr=on}} |width = {{convert|52|ft|m|abbr=on}} |grade =  }}

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 {{convert|2|mi|adj=on}}, 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.

Since the 2001 Nisqually earthquake, the replacement of the Alaskan Way Viaduct and Battery Street Tunnel had been the source of much political controversy demonstrating the Seattle process. Options for replacing the viaduct, which carried 110,000 vehicles per day, included replacing it with a cut-and-cover tunnel or a bored tunnel, replacing it with another elevated highway, or eliminating it while modifying other surface streets and public transportation. The current plan emerged in 2009 when government officials agreed to a deep-bore tunnel.

Construction began in July 2013 using "Bertha", at the time the world's largest-diameter tunnel boring machine. After several delays, tunnel boring was completed in April 2017, and the tunnel opened to traffic on February 4, 2019.

==Description== {{Multiple image | direction = vertical | total_width = 200 | image1 = SR 99 Tunnel south portal and Seattle skyline from Atlantic Street (19596995999).jpg | image2 = SR 99 Tunnel south portal from Atlantic Street overpass, Sept. 2018.jpg | caption2 = September 2018 | header = SR 99 Tunnel South portal progress | align = left | caption1 = July 2015 }} The SR 99 tunnel is a single tube that measures {{convert|9,270|ft|m}} long and {{convert|52|ft|m}} wide, carrying a double-decker highway that is {{convert|32|ft|m}} wide and has two lanes in each direction.<ref name="360Look">{{cite news |last=Porterfield |first=Elaine |date=May 2017 |title=Tunnel Vision: A 360 Look at Bertha Underground |url=https://www.seattlemag.com/news-and-features/tunnel-vision-360-look-bertha-underground |work=Seattle Magazine |access-date=December 25, 2018}}</ref><ref>{{cite news |date=May 2017 |title=Tunneling into the numbers |url=https://www.wsdot.wa.gov/Projects/Viaduct/Media/Default/-NewDocuments/Library/201705_AWVBytheNumbersFolio.pdf |publisher=Washington State Department of Transportation |access-date=December 30, 2018}}</ref><ref name="Times-Jan19QA">{{cite news |last1=Lindblom |first1=Mike |last2=Baruchman |first2=Michelle |date=January 31, 2019 |title=Highway 99 tunnel opens next week. Here are answers to your questions about the project |url=https://www.seattletimes.com/seattle-news/transportation/the-highway-99-tunnel-opens-next-week-here-are-answers-to-your-questions-about-the-project/ |work=The Seattle Times |access-date=January 31, 2019}}</ref> Each deck has two {{convert|11|ft|m|adj=mid}} lanes, an {{convert|8|ft|m|adj=mid}} west shoulder, and a {{convert|2|ft|m|adj=mid}} east shoulder.<ref name="Times-FAQ">{{cite news |last=Lindblom |first=Mike |date=November 19, 2018 |title=When does the viaduct close? How much is the tunnel toll? Your guide to Seattle's Highway 99 project |url=https://www.seattletimes.com/seattle-news/transportation/we-answer-your-questions-about-the-viaducts-closure-in-january-and-the-highway-99-tunnel-opening/ |work=The Seattle Times |access-date=December 25, 2018}}</ref> The decks are designed with banks of two degrees in turns and four-degree grades to facilitate designed speeds of {{convert|50|mph|kph}}.<ref name="Lindblom17">{{cite news |last=Lindblom |first=Mike |date=April 16, 2017 |title=Inside the Highway 99 tunnel: Bertha's done digging, but the roadway work rolls on |page=B1 |url=https://www.seattletimes.com/seattle-news/transportation/inside-highway-99-tunnel-bertha-roadwork-wsdot/ |work=The Seattle Times |access-date=December 25, 2018}}</ref><ref name="WSDOT-Inside">{{cite web |title=Seattle's new SR 99 tunnel |url=http://www.wsdot.wa.gov/Projects/Viaduct/using-the-new-sr-99-tunnel |publisher=Washington State Department of Transportation |access-date=December 25, 2018}}</ref> Below the highway decks are utility lines and mechanical spaces for the tunnel's ventilation, lighting, and fire suppression systems.<ref>{{cite news |date=April 4, 2017 |title=Life after Bertha: Focus shifts from mining to other tunnel work |url=http://www.wsdot.wa.gov/Projects/Viaduct/Status/Blog/life-after-Bertha |publisher=Washington State Department of Transportation |access-date=December 25, 2018}}</ref>

The tunnel has 15 emergency refuge areas located every {{convert|650|ft|m}} with escape routes that lead to the north and south portals. Variable message signs and emergency phones are also located throughout the entire tunnel.<ref name="WSDOT-Inside" /> The tunnel is monitored by over 300 security cameras that are fed into a WSDOT traffic control center in Shoreline that can dispatch incident response teams.<ref name="Lindblom17" /><ref name="KUOW-Jan">{{cite news |last=Martin |first=Casey |date=January 30, 2019 |title=Here's why it's safe to drive through the new tunnel |url=https://www.kuow.org/stories/transportation-officials-tout-highway-99-tunnel-safety |publisher=KUOW |access-date=January 31, 2019}}</ref> In the event of a fire, a set of fiber optic cables in the ceiling would sense heat and activate sprinklers.<ref>{{cite news |last=Minnick |first=Benjamin |date=March 28, 2018 |title=A trip inside our new 'smart' tunnel |url=https://www.djc.com/news/co/12109644.html |work=Seattle Daily Journal of Commerce |access-date=December 25, 2018}}</ref> A set of large fans located in the two portal operations buildings would then force smoke out through a set of {{convert|40|ft|m|adj=mid}} ventilation shafts.<ref name="Lindblom17" /><ref>{{cite news |last=Schlosser |first=Kurt |date=August 31, 2018 |title=Seattle tunnel's high-tech ventilation system designed to keep air fresh deep below ground |url=https://www.geekwire.com/2018/watch-seattle-tunnels-high-tech-ventilation-system-designed-keep-air-fresh-deep-ground/ |work=GeekWire |access-date=December 25, 2018}}</ref> The tunnel also has repeaters for cell phone and FM radio service; WSDOT can override the latter for emergency broadcasts.<ref name="Times-Jan19QA" /><ref name="KUOW-Jan" />

===Route=== [[File:Highway 99 tunnel south portal by stadiums crop.jpg|thumb|left|The completed south portal is seen behind Lumen Field in this aerial view.]]

The tunnel begins south of Downtown Seattle in the SoDo neighborhood, adjacent to the Port of Seattle's container ship terminal and the city's two outdoor sports stadiums, Lumen Field and T-Mobile Park. SR 99 enters the tunnel after passing Royal Brougham Way and an interchange with Alaskan Way at South Dearborn Street located adjacent to the south maintenance area and ventilation shaft.<ref name="Map">{{cite web |date=January 2017 |title=Traveling on the new SR 99 corridor |url=https://www.wsdot.wa.gov/Projects/Viaduct/Media/Default/-NewDocuments/Library/2017_0106_FutureAccess.pdf |publisher=Washington State Department of Transportation |access-date=December 25, 2018}}</ref> An additional set of ramps connect to South Royal Brougham Way and Colorado Avenue South, which terminates a block south at South Atlantic Street. The tunnel carries two lanes of southbound traffic on its upper deck and two lanes of northbound traffic on its lower deck,<ref name="Times-FAQ"/> and functions as a complete bypass of Downtown Seattle with no intermediate exits; it has a posted speed limit of {{convert|45|mph|kph}}.<ref name="Times-FAQ"/>

The tunnel travels northwesterly under Pioneer Square and Downtown Seattle, generally following 1st Avenue.<ref name="Map"/> It reaches its deepest point at Virginia Street, approximately {{convert|211|ft|m}} below street level, and begins its turn north through parts of Belltown and the Denny Triangle.<ref>{{cite web |date=July 2016 |title=Tunneling toward a new SR 99 corridor |url=http://www.wsdot.wa.gov/Projects/Viaduct/Media/Default/-NewDocuments/Library/2016_AWV_Tunneling_folio.pdf |publisher=Washington State Department of Transportation |access-date=December 25, 2018}}</ref> The tunnel emerges at a portal located west of Aurora Avenue and north of Harrison Street, adjacent to a tunnel operations building. SR 99 continues onto Aurora Avenue and crosses over Mercer Street, while an onramp allows access to the tunnel from 6th Avenue and an offramp carries tunnel traffic to Republican Street in South Lake Union.<ref name="Times-FAQ"/><ref name="Map"/>

===Tolls===

The SR 99 tunnel is tolled with a variable rate that changes based on time of the day, number of vehicle axles, and payment method. Tolls are collected electronically, with a lower rate for Good to Go pass users and a higher rate for scanned plates that are sent a bill in the mail.<ref>{{cite news |last=Lindblom |first=Mike |date=April 18, 2018 |title=Highway 99 tunnel tolls could range from $1 to $2.25, depending on time of day |url=https://www.seattletimes.com/seattle-news/transportation/highway-99-tunnel-tolls-could-range-from-1-to-2-25-depending-on-time-of-day/ |work=The Seattle Times |access-date=December 25, 2018}}</ref> Tolling began on 9 November 2019, with the rate for two-axle vehicles set at $1.20 to $2.70 for Good to Go users and $3.20 to $4.70 for pay-by-mail users.<ref>{{cite web |title=SR 99 Tunnel Toll Rates |url=https://wsdot.wa.gov/travel/roads-bridges/toll-roads-bridges-tunnels/sr-99-tunnel-tolling |publisher=Washington State Department of Transportation |access-date=July 21, 2023}}</ref><ref>{{cite news |date=October 16, 2018 |title=SR 99 tunnel toll rates will range from $1 to $2.25 in Seattle |url=https://www.king5.com/article/news/local/tunnel-effect/sr-99-tunnel-toll-rates-will-range-from-1-to-225-in-seattle/281-604872457 |publisher=KING 5 News |access-date=December 25, 2018}}</ref> The start of tolling was delayed by several months due to vendor issues and the viaduct demolition running behind schedule.<ref>{{cite news |last=Lindblom |first=Mike |date=June 12, 2019 |title=Highway 99 tunnel users won't have to pay tolls until sometime this fall |url=https://www.seattletimes.com/seattle-news/transportation/highway-99-tunnel-users-wont-have-to-pay-tolls-until-sometime-this-fall/ |work=The Seattle Times |access-date=June 12, 2019}}</ref> Toll collection is expected to yield $22 million in annual revenue, which will cover 6 percent of the construction costs of the tunnel megaproject and its debts; the toll-collection vendor will be paid $16 million for system setup and $29 million over a five-year period.<ref>{{cite news |last=Lindblom |first=Mike |date=November 12, 2019 |title=How is your Highway 99 toll money spent? A big chunk goes to collecting the tolls |url=https://www.seattletimes.com/seattle-news/transportation/how-is-your-highway-99-toll-money-spent-a-big-chunk-goes-to-collecting-the-tolls/ |work=The Seattle Times |access-date=November 20, 2019}}</ref> Beginning in 2022, the toll rates will increase by three percent annually with approval from the state transportation commission.<ref>{{cite web |date=October 2018 |title=SR 99 Tunnel Toll Rate Setting |url=http://wstc.wa.gov/HighwayTolling/SR99Rates/SR99/SR99TollRatesSetting.htm |publisher=Washington State Transportation Commission |access-date=February 9, 2019}}</ref>

==Planning history==

===Viaduct and earthquake risks=== {{main|Alaskan Way Viaduct}} thumb|The double-deck viaduct was a prominent feature of the waterfront [[File:The Alaskan Way Viaduct.jpg|thumb|The Alaskan Way Viaduct, as seen from Pike Place Market in August 2008]]

The Alaskan Way Viaduct was a double-decked elevated freeway that ran along Elliott Bay on the Downtown Seattle waterfront and, until January 11, 2019, when it was permanently closed, carried a section of State Route 99 (SR 99). It first opened to traffic on April 4, 1953, to provide a vehicular bypass of downtown for U.S. Route 99, the predecessor of SR 99; it connected with the Battery Street Tunnel, which opened the following year, and several downtown ramps that were completed years later.<ref name="PI-History">{{cite news |last=Lange |first=Larry |date=March 9, 2007 |title=Would a new viaduct be 'bigger and uglier'? |page=B1 |newspaper=Seattle Post-Intelligencer |url=https://www.seattlepi.com/local/transportation/article/Would-a-new-viaduct-be-bigger-and-uglier-1230640.php |access-date=December 26, 2018}}</ref> The viaduct and tunnel cost $18 million to construct (equivalent to ${{Format price|{{Inflation|US-GDP|18000000|1954}}}} in {{Inflation-year|US-GDP}} dollars){{inflation-fn|US-GDP}} and severed the waterfront from the rest of downtown.<ref>{{cite web |title=State of Washington, Department of Transportation (WSDOT), Alaskan Way Viaduct, Seattle, WA (1950-1959) |url=http://pcad.lib.washington.edu/building/5482/ |work=Pacific Coast Architecture Database |access-date=December 25, 2018}}</ref><ref>{{cite news |last=Diltz |first=Colin |date=November 22, 2018 |title=Seattle has changed: See the Alaskan Way Viaduct under construction in the 1950s |page=A1 |url=https://www.seattletimes.com/seattle-news/transportation/seattle-has-changed-see-the-alaskan-way-viaduct-take-shape-in-the-1950s/ |newspaper=The Seattle Times |access-date=December 25, 2018}}</ref>

The viaduct remained the primary north–south highway in Downtown Seattle until the construction of Interstate 5 (I-5) in the late 1960s. Weekday traffic volumes on the viaduct averaged around 110,000 vehicles per day in the mid-2000s, approximately half of equivalent sections on I-5.<ref>{{cite web |last=Ott |first=Jennifer |date=December 19, 2011 |title=Alaskan Way Viaduct, Part 4: Replacing the Viaduct |url=http://historylink.org/File/9983 |website=HistoryLink |access-date=December 26, 2018}}</ref><ref>{{cite web |url=http://www.wsdot.wa.gov/Projects/Viaduct/Contents/Item/Display/144 |title=Is most of the traffic using the viaduct today going to downtown or through downtown? |publisher=WSDOT |access-date=December 8, 2012 |archive-url=https://web.archive.org/web/20130427122459/http://www.wsdot.wa.gov/Projects/Viaduct/Contents/Item/Display/144 |archive-date=April 27, 2013 |url-status=live }}</ref> Calls to replace the viaduct and build a waterfront promenade surfaced as early as the late 1960s and early 1970s, increasing after the halted demolition of the Pike Place Market.<ref name="PI-History"/> The viaduct runs above the surface street, Alaskan Way, from S. Nevada Street in the south to the entrance of Belltown's Battery Street Tunnel in the north, following previously existing railroad lines.

The 1989 Loma Prieta earthquake destroyed the similarly designed Cypress Street Viaduct in Oakland, California, with the loss of 42 lives.<ref>{{cite web|url=http://home.pacbell.net/hywaymn/Cypress_Viaduct_Freeway.html |title=Cypress Viaduct Freeway |url-status=dead |archive-url=https://web.archive.org/web/20090707140502/http://home.pacbell.net/hywaymn/Cypress_Viaduct_Freeway.html |archive-date=July 7, 2009 }}</ref> The 2001 Nisqually earthquake damaged the viaduct and its supporting Alaskan Way Seawall and required the Washington State Department of Transportation (WSDOT) to invest US$14.5 million in emergency repairs. Experts gave a 1-in-20 chance that the viaduct could be shut down by an earthquake within the following decade.<ref>{{cite web |url=https://archive.seattletimes.com/archive/20020407/pviaduct07/dutiful-servant-brutal-barrier-the-viaduct-at-a-crossroads |title=Dutiful Servant, Brutal Barrier: The Viaduct at a Crossroads |work=Pacific Northwest |publisher=The Seattle Times |date=April 7, 2002 |first=Ross |last=Anderson |access-date=December 8, 2012 |archive-url=https://web.archive.org/web/20160304000615/http://community.seattletimes.nwsource.com/archive/?date=20020407&slug=pviaduct07 |archive-date=March 4, 2016 |url-status=live }}</ref> After the Nisqually earthquake, the viaduct was closed twice a year for WSDOT to conduct inspections of the structure.<ref>{{cite web |url=http://www.wsdot.wa.gov/Projects/Viaduct/About/ViaductInspections |title=Viaduct Inspections |publisher=Washington State Department of Transportation |year=2018 |archive-url=https://web.archive.org/web/20180906092354/http://www.wsdot.wa.gov/Projects/Viaduct/About/ViaductInspections |archive-date=September 6, 2018 |access-date=October 11, 2018}}</ref> Those inspections discovered continuing settlement damage. In 2005, a group of researchers and faculty from the University of Washington urged political officials to close the viaduct within a two-year timeframe.<ref>{{cite news |url=http://seattletimes.com/html/opinion/2002837776_viaduct02.html |title=Shut down the viaduct |date=March 2, 2006 |first1=Scott |last1=Miles |first2=David R. |last2=Montgomery |first3=Bill |last3=Beyers |newspaper=The Seattle Times |access-date=December 8, 2012 |archive-url=https://web.archive.org/web/20121008111126/http://seattletimes.com/html/opinion/2002837776_viaduct02.html |archive-date=October 8, 2012 |url-status=live }}</ref>

===Options and political debate=== thumb|The Alaskan Way Viaduct seen from Elliott Bay in May 2007

thumb|The view beneath the viaduct in August 2008; opponents of a new viaduct argued that the enlarged replacement would put more of the waterfront in shadow.<ref>{{cite news |url=http://www.thestranger.com/seattle/Content?oid=161447 |title=No and Hell No |newspaper=The Stranger |first=Erica C. |last=Barnett |date=February 22, 2007 |access-date=November 25, 2008 |archive-url=https://web.archive.org/web/20080919092332/http://www.thestranger.com/seattle/Content?oid=161447 |archive-date=September 19, 2008 |url-status=live }}</ref>

[[File:Milepost 31 storefront.JPG|thumb|Milepost 31, the SR 99–Alaskan Way Viaduct Replacement project information center in Pioneer Square]]

[[File:Front of model of tunnel boring machine at Milepost 31.JPG|thumb|Front of a model of the tunnel boring machine at Milepost 31, the tunnel project information center]]

Several replacement proposals were developed. Many Seattle leaders, including then-Mayor Greg Nickels and state and city transportation officials, favored building a tunnel. Plans for a six-lane, "cut-and-cover" double-decker tunnel were developed.<ref name="seattle channel">{{cite web|url=http://www.seattlechannel.org/issues/viaduct.asp |title=Alaskan Way Viaduct In-depth |publisher=Seattle Channel |access-date=December 8, 2012 |url-status=dead |archive-url=https://web.archive.org/web/20121228222304/http://www.seattlechannel.org/issues/viaduct.asp |archive-date=December 28, 2012 }} (See the "Background" tab in particular.)</ref> The tunnel was envisioned to solve not only the viaduct's traffic limitations and safety problems, but also to allow better uses for the waterfront real estate, including parks, housing, and retail developments. While future development of the Alaskan Way real estate corridor may provide tax revenue for the city, many state lawmakers objected to the cost of the proposed six-lane tunnel.{{citation needed|date=December 2012}} One criticism compared the plan to Boston's Big Dig project, which was said to illustrate the schedule and budget challenges of a large cut-and-cover tunnel. Proponents responded that the Seattle proposal was significantly smaller in scale than the Big Dig.<ref name="little dig" />

Another proposal aimed to replace the current viaduct with another elevated structure with updated seismic standards. This new viaduct would be larger, {{convert|12|ft|adj=on}} wide lanes with new shoulders on both sides, compared to the structure it would replace, which had no shoulders and lanes as narrow as {{convert|10|ft}} in places. The on and off ramps at the northern and southern portion of the viaduct would remain the same with an additional full intersection at South Atlantic Street and South Royal Brougham Way. The First Avenue off ramp would be removed. The plan included a complete replacement of the sea wall. It was estimated to cost $2.8 billion and take 10–12 years to construct.<ref>{{cite web |url=http://www.wsdot.wa.gov/Projects/Viaduct/Alternatives.htm |title=WSDOT Viaduct Alternatives Information |archive-url=https://web.archive.org/web/20061026053920/http://www.wsdot.wa.gov/Projects/Viaduct/Alternatives.htm |archive-date=October 26, 2006 |publisher=WSDOT}}</ref> Many prominent leaders and organizations opposed the elevated structure and believed this was a unique opportunity to remove the viaduct and connect downtown Seattle to the waterfront. Former Governors Dan Evans and Gary Locke, former U.S. Senator Slade Gorton,<ref>{{cite news |last=Gilmore |first=Susan |date=December 12, 2006 |title=Opposition to viaduct addressed to Gregoire |publisher=Seattle Times |url=https://www.seattletimes.com/seattle-news/opposition-to-viaduct-addressed-to-gregoire/ |archive-url=https://web.archive.org/web/20181012051134/https://www.seattletimes.com/seattle-news/opposition-to-viaduct-addressed-to-gregoire/| archive-date=October 12, 2018| access-date=October 11, 2018}}</ref> and the American Institute of Architects<ref>{{cite news |last=Bennett |first=Sam |title=Tunnel to replace Alaskan Way Viaduct in Seattle |publisher=Daily Journal of Commerce |place=Portland, OR |date=January 14, 2009 |via=Newspaper Source Plus}}</ref> recommended against rebuilding the viaduct.

WSDOT evaluated five proposals in 2003–2004 and decided that the six-lane cut-and-cover tunnel was the preferred alternative. Rebuilding the viaduct was retained as a backup plan.<ref name="Final EIS App B">{{cite book |url=http://data.wsdot.wa.gov/publications/viaduct/AWVFEIS-AppendixB.pdf |title=Alaskan Way Viaduct Replacement Project: Final Environmental Impact Statement |chapter=Appendix B: Alternatives Description and Construction Methods |date=July 2011 |publisher=WSDOT |access-date=December 11, 2012 |archive-url=https://web.archive.org/web/20140710094449/http://data.wsdot.wa.gov/publications/viaduct/AWVFEIS-AppendixB.pdf |archive-date=July 10, 2014 |url-status=live }}</ref>

However, due to the costs and scope of the project, other options were still being discussed in the local media. A proposal to remove the viaduct and replace it with surface street and transit improvements was backed by former King County Executive Ron Sims,<ref>{{cite news |url=http://search.komonews.com/blankpage?page=details&pid=5941281&id=88354175 |title=Gregoire nixes surface option for viaduct |date=February 19, 2007 |publisher=KOMONews.com |agency=AP |access-date=December 7, 2012 |archive-url=https://web.archive.org/web/20160304063245/http://search.komonews.com/blankpage?page=details&pid=5941281&id=88354175 |archive-date=March 4, 2016 |url-status=live }}</ref> the People's Waterfront Coalition,<ref name="CNU" /> and the Congress for the New Urbanism.<ref name="CNU">{{cite web |url=http://www.cnu.org/highways/seattle |title=Seattle's Alaskan Way Viaduct |publisher=Congress for the New Urbanism |access-date=December 8, 2012 |archive-url=https://web.archive.org/web/20130107064716/http://www.cnu.org/highways/seattle |archive-date=January 7, 2013 |url-status=dead }}</ref> Proponents of this plan offered examples of successes in removing highways in other cities. They envisioned the waterfront becoming a pedestrian-friendly neighborhood with a mix of commercial, retail, and public park spaces. Traffic needs would be addressed through modifications to existing streets, I-5, and public transit; they argued that these modifications would be desirable in any event. Proponents further argued that this plan had the potential to improve the tourist economy, create jobs, and encourage a denser and more residential downtown through the offering of a generous waterfront park.<ref>{{cite web |url=http://www.thestranger.com/seattle/stop-the-insanity/Content?oid=7200124 |title=Stop the Insanity |newspaper=The Stranger |first=Dominic |last=Holden |date=March 16, 2011 |access-date=August 1, 2013 |archive-url=https://web.archive.org/web/20130728110404/http://www.thestranger.com/seattle/stop-the-insanity/Content?oid=7200124 |archive-date=July 28, 2013 |url-status=live }}</ref> The total cost of removal of the viaduct, repairing the seawall, and improvements to I-5 and existing streets was unofficially estimated to be $1.6 billion.{{Citation needed|date=September 2009}} In 2006, Seattle City Council member Peter Steinbrueck noted, "While the mayor's first choice is the tunnel, he supports the City Council's resolution that designates a surface and transit alternative as a backup."<ref>{{cite news |url=https://archive.seattletimes.com/archive/20061010/steinbrueck10/climates-right-for-fresh-viaduct-plan |title=Climate's Right For Fresh Viaduct Plan |first=Peter |last=Steinbrueck |date=October 10, 2006 |newspaper=The Seattle Times |access-date=December 8, 2012 |archive-url=https://web.archive.org/web/20120826005417/http://community.seattletimes.nwsource.com/archive/?date=20061010&slug=steinbrueck10 |archive-date=August 26, 2012 |url-status=live }}</ref>

In response to concerns about the cost of the originally proposed tunnel construction, the city council created a scaled-down, four-lane hybrid tunnel option. This would have combined the smaller tunnel with surface transit improvements to address traffic needs. The tunnel's {{convert|14|ft|m|adj=on}} shoulders would be used as an extra travel lane each way during periods of high demand. Transit service would be increased during peak commuter periods. Cars entering and exiting from Elliott and Western Avenues would each have a dedicated lane. Third Avenue would become a permanent transit corridor. The cost estimate for the four-lane tunnel was $3.4 billion.<ref>{{cite news |last1=Garber |first1=Andrew |last2=Young |first2=Bob |last3=Gilmore |first3=Susan |title=Nickels' backing for 4-lane "tunnel lite" gets cool reception |url=https://www.seattletimes.com/seattle-news/nickels-backing-for-4-lane-tunnel-lite-gets-cool-reception/ |access-date=February 7, 2019 |work=The Seattle Times |date=January 17, 2007}}</ref> On February 13, 2007, Governor Christine Gregoire rejected the tunnel hybrid option, saying that a WSDOT review showed the tunnel proposal "does not meet state and federal safety standards." Of particular concern was that the use of shoulders as traffic lanes during peak traffic times would leave no additional lanes for emergency access.<ref>{{cite news|url=http://seattletimes.com/html/localnews/2003571128_viaductreport14m0.html |archive-url=https://archive.today/20130202222454/http://seattletimes.com/html/localnews/2003571128_viaductreport14m0.html |url-status=dead |archive-date=February 2, 2013 |title=State says no tunnel; mayor still wants vote |date=February 14, 2007 |first1=Andrew |last1=Garber |first2=Susan |last2=Gilmore |first3=Mike |last3=Lindblom |newspaper=The Seattle Times }}</ref> However, several of the viaduct "stakeholders committee" brought on board to advise the city indicated that the tunnel option should remain on the table.<ref>{{cite news|url=http://seattletimes.com/html/localnews/2008619010_webviaduct12m.html |title=City, county, state agree on tunnel to replace viaduct |newspaper=The Seattle Times |date=January 12, 2009 |first1=Andrew |last1=Garber |first2=Mike |last2=Lindblom |first3=Emily |last3=Heffter |url-status=dead |archive-url=https://web.archive.org/web/20121013133922/http://seattletimes.com/html/localnews/2008619010_webviaduct12m.html |archive-date=October 13, 2012 }}</ref>

State and city officials deadlocked in late 2006 over whether to build an elevated structure (the state's preference) or a hybrid tunnel (the city's preference). Governor Gregoire stated "no action" was not an option for the viaduct.<ref>{{cite news |url=http://www.seattlepi.com/local/transportation/article/Tunnel-option-off-table-for-viaduct-replacement-1225701.php |title=Tunnel option off table for viaduct replacement |date=January 17, 2007 |newspaper=Seattle Post-Intelligencer |first1=Chris |last1=McGann |first2=Melissa |last2=Santos |first3=Larry |last3=Lange |access-date=December 8, 2012 |archive-url=https://web.archive.org/web/20121015084440/http://www.seattlepi.com/local/transportation/article/Tunnel-option-off-table-for-viaduct-replacement-1225701.php |archive-date=October 15, 2012 |url-status=live }}</ref> The state government called for an advisory ballot on March 13, 2007, for Seattle residents, which was supported by the city council. The advisory ballot allowed Seattleites to vote on whether they supported a surface-tunnel hybrid and whether they supported an elevated structure.<ref name="Mar13">{{cite news|url=http://seattletimes.nwsource.com/html/politics/2003533235_viaductvote20m.html |newspaper=The Seattle Times |title=Viaduct vote set; state may ignore it |date=March 7, 2007 |first=Bob |last=Young |url-status=dead |archive-url=https://web.archive.org/web/20080706041118/http://seattletimes.nwsource.com/html/politics/2003533235_viaductvote20m.html |archive-date=July 6, 2008 }}</ref> Voters rejected both options, with the surface-tunnel hybrid getting only 30% support and the elevated structure only 43%.<ref>{{cite web |url=http://your.kingcounty.gov/elections/200703/res.htm |title=King County Election Results (Mar. 13 special election) |publisher=King County |date=March 27, 2007 |access-date=December 8, 2012 |archive-url=https://web.archive.org/web/20120823013319/http://your.kingcounty.gov/elections/200703/res.htm |archive-date=August 23, 2012 |url-status=live }}</ref>

Mayor Mike McGinn, elected in 2009 and opposed to highway expansion, joined other tunnel opposition groups to refer city council-approved agreements about the tunnel to the voters as a citizen's referendum.<ref name="NYT-Aug11">{{cite news |last=Yardley |first=William |date=August 19, 2011 |title=Seattle, After Decade of Debate, Approves Tunnel |page=A13 |url=https://www.nytimes.com/2011/08/19/us/19seattle.html |work=The New York Times |access-date=December 23, 2018}}</ref> The referendum was initially blocked by a lawsuit from the city, but was pared down to one aspect of the city's approval for the project and placed on the August 2011 ballot.<ref>{{cite news |last1=Thompson |first1=Lynn |last2=Lindblom |first2=Mike |date=May 21, 2011 |title=Judge: Anti-tunnel measure going on August ballot |page=A1 |url=http://old.seattletimes.com/html/localnews/2015105379_tunnelpreview21m.html |work=The Seattle Times |access-date=February 4, 2019}}</ref><ref>{{cite web|url=https://aqua.kingcounty.gov/elections2/contests/measureinfo.aspx?cid=38653&eid=1248|title=Referendum 1 (August 2011)|publisher=King County Elections|access-date=February 4, 2019}}</ref> Under the ruling, the referendum would only challenge one section of the original 140-page City Council ordinance that approved agreements over street use, utilities, design and liability for the tunnel following completion of the project's ongoing environmental review process. The referendum vote approved the City Council's actions by 58 percent on August 16, 2011.<ref>{{cite news |date=August 17, 2011 |title=Voters backing Seattle tunnel; fight may finally be over |page=A1 |url=http://old.seattletimes.com/html/localnews/2015928327_elextunnel17m.html |work=The Seattle Times |access-date=February 4, 2019}}</ref> The Federal Highway Administration completed its analysis of the project's final EIS and issued its record of decision with WSDOT later that month, allowing pre-construction activities to begin.<ref>{{cite news |last=Gutierrez |first=Scott |date=August 23, 2011 |title=SR 99 deep bore tunnel gets federal approval |url=https://www.seattlepi.com/local/transportation/article/SR-99-deep-bore-tunnels-gets-federal-approval-2137635.php |work=Seattle Post-Intelligencer |access-date=December 23, 2018}}</ref>

===Bored tunnel selection=== thumb|Two columns from the demolished portion of Alaskan Way Viaduct

In January 2008, as debate on its replacement continued, Governor Gregoire announced that the State of Washington would take down the viaduct in 2012.<ref>{{cite news |url=http://www.seattlepi.com/local/transportation/article/Gregoire-Watch-me-tear-down-the-viaduct-1260638.php |title=Gregoire: 'Watch me' tear down the viaduct |date=January 3, 2008 |newspaper=Seattle Post-Intelligencer |first=Chris |last=McGann |access-date=December 8, 2012 |archive-url=https://web.archive.org/web/20121015084457/http://www.seattlepi.com/local/transportation/article/Gregoire-Watch-me-tear-down-the-viaduct-1260638.php |archive-date=October 15, 2012 |url-status=live }}</ref> On January 12, 2009, the state of Washington, King County, the city of Seattle, and the Port of Seattle revealed that they had agreed to replace the viaduct with a bored tunnel.<ref name="TunnelAnnounce">{{cite news|first=Andrew |last=Garber |title=Tunnel in place of viaduct: A deal, but how to pay? |url=http://seattletimes.nwsource.com/html/localnews/2008621043_viaduct13m.html |work=The Seattle Times |date=January 13, 2009 |url-status=dead |archive-url=https://web.archive.org/web/20090115000109/http://seattletimes.nwsource.com/html/localnews/2008621043_viaduct13m.html |archive-date=January 15, 2009 }}</ref> On March 4, 2009, the state senate passed a bill endorsing the tunnel option.<ref>{{cite news |url=http://blog.seattletimes.nwsource.com/politicsnorthwest/2009/03/04/senate_passes_bill_to_replace.html |title=Senate passes bill to replace viaduct with tunnel |date=March 4, 2009 |first=Andrew |last=Garber |newspaper=The Seattle Times |access-date=March 5, 2009 |archive-url=https://web.archive.org/web/20101112071836/http://blog.seattletimes.nwsource.com/politicsnorthwest/2009/03/04/senate_passes_bill_to_replace.html |archive-date=November 12, 2010 |url-status=dead }}</ref> On May 12, 2009, Governor Gregoire signed [http://apps.leg.wa.gov/billinfo/summary.aspx?year=2009&bill=5768 Senate Bill 5768], authorizing $2.8 billion in state funds for a possible deep-bore tunnel.

Disparate factions, ranging from some environmentalists to some industrialists, criticized the tunnel decision.<ref name="TunnelAnnounce" /><ref name="TunnelOfficial">{{cite news|first=Mike |last=Lindblom |author2=Sara Jean Green |title=Gregoire announces tunnel plans; car-tab taxes might help pay for it |url=http://seattletimes.nwsource.com/html/localnews/2008622393_webviaduct13m.html |newspaper=The Seattle Times |date=January 13, 2009 |url-status=dead |archive-url=https://web.archive.org/web/20090115232433/http://seattletimes.nwsource.com/html/localnews/2008622393_webviaduct13m.html |archive-date=January 15, 2009 }}</ref> A business owner argued that the restrictions on hazardous cargo through the tunnel would restrict movement of freight through downtown,<ref name="TunnelOfficial" /> though hazardous cargo had already been prohibited from the Battery Street Tunnel and the viaduct at peak hours.<ref>{{cite web|url=http://www.wsdot.wa.gov/Projects/Viaduct/Contents/Item/Display/156|title=Alaskan Way Viaduct: Will there be restrictions on freight using the tunnel?|work=wa.gov|access-date=August 3, 2015|archive-url=https://web.archive.org/web/20150912180250/http://www.wsdot.wa.gov/Projects/Viaduct/Contents/Item/Display/156|archive-date=September 12, 2015|url-status=live}}</ref> Similarly, another argued that surface traffic would increase, which would cause further problems to downtown freight transport.<ref name="TunnelAnnounce" /> A chairman of a local Sierra Club chapter argued that the large investment in automobile transport did not take into account global warming concerns.<ref name="TunnelAnnounce" />

==Design and funding== [[File:Jumbo Fairpartner, Seattle, April 2013.jpg|thumb|Freighter ''Fairpartner'' carrying the disassembled tunnel boring machine into the Port of Seattle]]

The approved design is a four-lane, {{convert|2|mi|km|adj=on}} long bored tunnel.<ref name="TunnelAnnounce" /> The tunnel has a south portal in SoDo, near Lumen Field, and a north portal in South Lake Union, east of Seattle Center.<ref name="TunnelOfficial" /> The route goes beneath Pioneer Square, the central business district of Downtown, and Belltown.

The project is estimated to cost US$3.29 billion, with $2.8 billion coming from the state and federal governments to cover the tunnel boring and a new interchange in SoDo.<ref name="budget">{{cite web |url=http://www.wsdot.wa.gov/Projects/Viaduct/Budget |title=Alaskan Way Viaduct: Budget |publisher=WSDOT |access-date=February 5, 2019}}</ref> The replacement project also includes the following projects and funding sources: * The city of Seattle will fund surface street improvements, utility relocation, and repairs to the Alaskan Way Seawall, which was also damaged in the 2001 Nisqually earthquake.<ref name="TunnelOfficial" /> * Since the proposed tunnel will contain two lanes in each direction as opposed to the viaduct's three, and no Western Avenue exit to serve the Belltown, Interbay, Magnolia, and Ballard areas, King County will fund transit improvements to offset the loss.<ref name="TunnelOfficial" /> * The Port of Seattle approved a $267.7 million contribution.<ref name="budget" /> * $200 million will be collected from tolls<ref name="budget" /> at rates set by the Washington State Transportation Commission<ref>{{cite web |url=http://www.wsdot.wa.gov/Projects/Viaduct/Contents/Item/Display/493 |title=Will tolling cause diversion? |access-date=December 26, 2013 |publisher=WSDOT |archive-url=https://web.archive.org/web/20140712103641/http://www.wsdot.wa.gov/Projects/Viaduct/Contents/Item/Display/493 |archive-date=July 12, 2014 |url-status=live }}</ref> with input from the Advisory Committee on Tolling and Traffic Management.<ref>{{cite web |url=http://www.wsdot.wa.gov/projects/viaduct/Library/Meetings/ACTTM |title=Advisory Committee on Tolling and Traffic Management (2011–present) |access-date=December 26, 2013 |publisher=WSDOT |archive-url=https://web.archive.org/web/20140214230559/http://www.wsdot.wa.gov/projects/viaduct/Library/Meetings/ACTTM |archive-date=February 14, 2014 |url-status=live }}</ref>

WSDOT began part of the larger project in 2008, while the replacement debate was still on-going, by repairing some of the viaduct columns.<ref name="schedule">{{cite web |author=Seattle Tunnel Partners |date=December 1, 2015 |title=Seattle Tunnel Partners monthly schedule: November 2015 |url=http://www.wsdot.wa.gov/Projects/Viaduct/Media/Default/-NewDocuments/Schedule/STP_Schedule_November_2015.pdf |publisher=Washington State Department of Transportation |access-date=December 27, 2015 |archive-url=https://web.archive.org/web/20151228040445/http://www.wsdot.wa.gov/Projects/Viaduct/Media/Default/-NewDocuments/Schedule/STP_Schedule_November_2015.pdf |archive-date=December 28, 2015 |url-status=live }}</ref>

The $80 million tunnel boring machine (TBM) Bertha was created for this project by Hitachi Zosen Corporation near Osaka, Japan. The {{convert|326|ft|abbr=on}}, {{convert|6700|short ton|adj=on}} TBM was disassembled into 40 pieces and shipped to Seattle, where it was reassembled in the launch pit near the south end of the future tunnel.<ref name="tour Sep 2012">{{cite video |people=Robinson, Patrick |date=September 7, 2012 |title=Seattle Deep Bore Tunnel Tour Sept. 6, 2012 |url=https://www.youtube.com/watch?v=s0NF_9EkKFE |publisher=West Seattle Herald |access-date=December 1, 2016 |archive-url=https://web.archive.org/web/20160425055801/https://www.youtube.com/watch?v=s0NF_9EkKFE |archive-date=April 25, 2016 |url-status=live }}</ref> From there, the record-breaking {{convert|57.5|ft|adj=on}} diameter borer would move in {{convert|6.5|ft|abbr=on}} increments toward the north end.<ref name="PM Aug 2012">{{cite web |url=http://www.popularmechanics.com/technology/engineering/extreme-machines/digging-the-worlds-widest-tunnel-under-downtown-seattle-12203389 |title=Digging an Enormous Tunnel Under Downtown Seattle |work=Popular Mechanics |date=August 30, 2012 |first=Tim |last=Newcomb |access-date=December 9, 2012 |archive-url=https://web.archive.org/web/20121105061605/http://www.popularmechanics.com/technology/engineering/extreme-machines/digging-the-worlds-widest-tunnel-under-downtown-seattle-12203389 |archive-date=November 5, 2012 |url-status=live }}</ref><ref name="NYT Dec 2012">{{cite news |url=https://www.nytimes.com/2012/12/05/us/projects-to-transform-seattle-all-along-the-waterfront.html |title=Engineering Projects Will Transform Seattle, All Along the Waterfront |newspaper=The New York Times |date=December 4, 2012 |first=Kirk |last=Johnson |access-date=February 26, 2017 |archive-url=https://web.archive.org/web/20161109183149/http://www.nytimes.com/2012/12/05/us/projects-to-transform-seattle-all-along-the-waterfront.html |archive-date=November 9, 2016 |url-status=live }}</ref>

WSDOT nicknamed the TBM "Bertha" after Seattle's first female mayor, Bertha Knight Landes. This name was chosen from names submitted by kindergarten through 12th grade students for a naming competition.<ref name="TBM name">{{cite web|url=http://www.wsdot.wa.gov/News/2012/12/10_sr99_tunnel-machine-name.htm |title=SR 99 tunneling machine tweets her name: Bertha |publisher=WSDOT |access-date=December 10, 2012 |url-status=dead |archive-url=https://web.archive.org/web/20141110124014/http://www.wsdot.wa.gov/News/2012/12/10_sr99_tunnel-machine-name.htm |archive-date=November 10, 2014 }}</ref>

==Construction== thumb|Cutting head of the tunnel boring machine prior to tunneling, 2013 thumb|Back of tunnel boring machine and partially completed tunnel with concrete walls in place in 2017

The primary construction contractor was Seattle Tunnel Partners (STP). The initial phase of demolition and removal of the viaduct began on October 21, 2011, to prepare the southern portal. Only a southern portion of the viaduct was removed at that time; the viaduct along the central waterfront remained open for traffic until the tunnel was complete.<ref>{{cite news |last=Gutierrez |first=Scott |title=Alaskan Way Viaduct closure, demolition begin |url=http://www.seattlepi.com/local/transportation/article/Countdown-to-the-Alaskan-Way-Viaduct-closure-2228936.php#page-1 |newspaper=Seattle Post-Intelligencer |date=October 22, 2011 |access-date=July 16, 2012 |archive-url=https://web.archive.org/web/20111117133912/http://www.seattlepi.com/local/transportation/article/Countdown-to-the-Alaskan-Way-Viaduct-closure-2228936.php#page-1 |archive-date=November 17, 2011 |url-status=live }}</ref><ref>{{cite web |url=http://www.wsdot.wa.gov/Projects/Viaduct/Contents/Item/Display/486 |title=When will the viaduct be demolished? |access-date=December 10, 2014 |publisher=WSDOT |archive-url=https://web.archive.org/web/20150417155611/http://www.wsdot.wa.gov/Projects/Viaduct/Contents/Item/Display/486 |archive-date=April 17, 2015 |url-status=live }}</ref>

Boring of the tunnel with the {{convert|57.5|ft|adj=on}} diameter "Bertha," at the time the world's largest-diameter tunnel-boring machine, began on July 30, 2013,<ref>{{cite press release|title=Bertha starts digging: tunneling underway in Seattle|date=July 30, 2013|publisher=Washington State Department of Transportation|url=http://www.wsdot.wa.gov/News/2013/07/30_SR99BerthaStartsDigging.htm|last=Yerkan|first=KaDeena|access-date=December 5, 2015|url-status=live|archive-url=https://web.archive.org/web/20151208144140/http://www.wsdot.wa.gov/News/2013/07/30_SR99BerthaStartsDigging.htm|archive-date=December 8, 2015}}</ref><ref>{{cite news|url=http://www.seattletimes.com/seattle-news/bertharsquos-excavation-mission-beginning-under-downtown/|title=Bertha's excavation mission beginning under downtown|last=Lindblom|first=Mike|date=July 30, 2013|newspaper=The Seattle Times|access-date=December 5, 2015|archive-url=https://web.archive.org/web/20151215184355/http://www.seattletimes.com/seattle-news/bertharsquos-excavation-mission-beginning-under-downtown/|archive-date=December 15, 2015|url-status=live}}</ref> and at the time was expected to be completed in 14 months.<ref name="KN13">{{cite news|url=http://www.komonews.com/news/local/Bertha-takes-first-bite-of-new-Seattle-tunnel-217761601.html|title=Bertha takes first bite of new Seattle tunnel|last=Esser|first=Doug|date=July 31, 2013|access-date=July 31, 2013|archive-url=https://web.archive.org/web/20130803103138/http://www.komonews.com/news/local/Bertha-takes-first-bite-of-new-Seattle-tunnel-217761601.html|archive-date=August 3, 2013|url-status=live|publisher=KOMO}}</ref> After three weeks of drilling, the project was estimated to be two weeks behind schedule; problems with fiberglass near the front of the drill and a labor dispute with a local longshoreman's union were blamed.<ref>{{cite news|url=http://seattletimes.com/html/localnews/2021696892_99tunnelxml.html |title=Huge tunneling machine off to painfully slow start |date=August 27, 2013 |newspaper=The Seattle Times |first=Mike |last=Lindblom |url-status=dead |archive-url=https://web.archive.org/web/20131228200658/http://seattletimes.com/html/localnews/2021696892_99tunnelxml.html |archive-date=December 28, 2013 }}</ref> Work was halted on December 6, 2013 after the machine overheated and shut down <ref>{{cite news|url=https://www.seattletimes.com/seattle-news/transportation/insurance-lawyers-new-findings-increase-arguments-in-case-of-bertha-machine-breakdown/|title=Insurance lawyers' new findings increase arguments in case of Bertha machine breakdown|last=Lindblom|first=Mike|date=August 19, 2017|newspaper=The Seattle Times|access-date=August 19, 2017|archive-url=https://web.archive.org/web/20170819190049/http://www.seattletimes.com/seattle-news/transportation/insurance-lawyers-new-findings-increase-arguments-in-case-of-bertha-machine-breakdown/|archive-date=August 19, 2017|url-status=live}}</ref> approximately {{convert|1,083|ft|m}} into the planned {{convert|9,270|ft|m|adj=mid|-long}} route. Investigations later revealed the seal system that protects the machine's main bearing had been damaged. Three days prior to stopping, the machine mined through a hollow, 8-inch steel well-casing and pipe used to measure groundwater in 2002 around Alaskan Way, which was drilled as part of the planning phases of the project.<ref>{{cite news|url=http://blogs.seattletimes.com/today/2014/01/whats-blocking-bertha-a-huge-steel-pipe/|title=What's blocking Bertha: a long steel pipe|last=Lindblom|first=Mike|date=January 3, 2014|newspaper=The Seattle Times|access-date=January 4, 2014|archive-url=https://web.archive.org/web/20140104212538/http://blogs.seattletimes.com/today/2014/01/whats-blocking-bertha-a-huge-steel-pipe/|archive-date=January 4, 2014|url-status=live}}</ref> The unexpected discovery of the pipe was blamed by the contractor for the work stoppage in litigation, but STP later admitted to its knowledge of the pipe's location prior to the start of tunnel boring.<ref name="Times-Dec19"/><ref>{{cite news|url=https://www.seattletimes.com/seattle-news/bad-news-bertha-is-damaged/|title=Bad news: Bertha is damaged|last=Lindblom|first=Mike|date=February 7, 2014|newspaper=The Seattle Times|access-date=February 7, 2014|archive-url=https://web.archive.org/web/20150324161828/http://www.seattletimes.com/seattle-news/bad-news-bertha-is-damaged/|archive-date=March 24, 2015|url-status=live}}</ref> This delay lasted for more than two years as the workers had to dig a {{convert|120|ft|adj=on}} vertical shaft down to Bertha's cutting head to repair it. Settling was discovered in Pioneer Square that may be related to this additional excavation.<ref name="NYT 2014-12">{{cite news|url=https://www.nytimes.com/2014/12/10/us/in-seattle-a-sinking-feeling-about-a-troubled-tunnel.html|title=In Seattle, a Sinking Feeling About a Troubled Tunnel|last=Johnson|first=Kirk|date=December 9, 2014|newspaper=The New York Times|access-date=February 26, 2017|archive-url=https://web.archive.org/web/20160314090948/http://www.nytimes.com/2014/12/10/us/in-seattle-a-sinking-feeling-about-a-troubled-tunnel.html|archive-date=March 14, 2016|url-status=live}}</ref>

Tunnel boring had resumed on December 22, 2015.<ref>{{cite press release|title=Bertha tunnels into next phase of testing|date=December 22, 2015|publisher=Washington State Department of Transportation|url=http://www.wsdot.wa.gov/News/2015/12/22_berthatunneling.htm|last=Newborn|first=Laura|access-date=December 27, 2015|url-status=live|archive-url=https://web.archive.org/web/20151227032856/http://www.wsdot.wa.gov/News/2015/12/22_berthatunneling.htm|archive-date=December 27, 2015}}</ref><ref name="Times-2015Resume">{{cite news|url=http://www.seattletimes.com/seattle-news/transportation/bertha-restarts-after-two-years-of-delays/|title=Bertha back on the move after 2 years of delays|last=Lindblom|first=Mike|date=December 22, 2015|newspaper=The Seattle Times|access-date=December 27, 2015|archive-url=https://web.archive.org/web/20160105182306/http://www.seattletimes.com/seattle-news/transportation/bertha-restarts-after-two-years-of-delays/|archive-date=January 5, 2016|url-status=live}}</ref> The tunnel boring was halted 23 days later on January 14, 2016, after a {{convert|30|ft|m|adj=mid|-wide}} sinkhole developed on the ground in front of the machine, causing Governor Jay Inslee to halt drilling until the contractors can perform a root cause analysis to show that the machine can be run safely.<ref>{{cite news |last=Lindblom |first=Mike |date=January 14, 2016 |title=Inslee orders tunnel dig halted as soil sinks above Bertha |url=http://www.seattletimes.com/seattle-news/transportation/inslee-orders-bertha-tunneling-stopped-after-sinkhole-forms/ |newspaper=The Seattle Times |access-date=January 15, 2016 |archive-url=https://web.archive.org/web/20160206214846/http://www.seattletimes.com/seattle-news/transportation/inslee-orders-bertha-tunneling-stopped-after-sinkhole-forms/ |archive-date=February 6, 2016 |url-status=live }}</ref> Even though contractors filled the hole with {{convert|250|cuyd}} of material, the ground above the tunnel-boring machine continued to sink, according to the Washington State Department of Transportation. The tunneling restriction was lifted on February 23, 2016, and tunneling resumed that day.<ref name="wsddd">{{cite web|url=http://www.wsdot.wa.gov/Projects/Viaduct/library/advisories-and-updates/mining-operations-resume-on-tuesday|title=Feb. 23 project update: Seattle Tunnel Partners resumes mining|date=February 23, 2016|archive-url=https://web.archive.org/web/20160223220618/http://www.wsdot.wa.gov/Projects/Viaduct/library/advisories-and-updates/mining-operations-resume-on-tuesday|archive-date=February 23, 2016|url-status=live|access-date=February 23, 2016}}</ref> Bertha passed under the Alaskan Way Viaduct in early May, closing the roadway for 11 days as the machine had {{convert|15|ft|m}} of vertical clearance under the structure's pilings.<ref>{{cite news |last=Demay |first=Daniel |date=May 11, 2016 |title=Viaduct closure ends, Bertha to make pit stop |url=http://www.seattlepi.com/local/transportation/article/Viaduct-closure-ends-Bertha-to-make-pit-stop-7423291.php |newspaper=Seattle Post-Intelligencer |access-date=July 20, 2016 |archive-url=https://web.archive.org/web/20160714080739/http://www.seattlepi.com/local/transportation/article/Viaduct-closure-ends-Bertha-to-make-pit-stop-7423291.php |archive-date=July 14, 2016 |url-status=live }}</ref> On April 4, 2017, the tunnel boring machine broke through to the recovery pit on the north end of the tunnel, completing the excavation process.<ref name="seatimes-bertha-040417">{{cite news |last=Lindblom |first=Mike |date=April 4, 2017 |title=Bertha's breakthrough just 'halftime' for tunnel project |url=http://www.seattletimes.com/seattle-news/transportation/sense-of-history-builds-as-tunnel-machine-bertha-inches-toward-daylight/ |newspaper=The Seattle Times |access-date=April 4, 2017 |archive-url=https://web.archive.org/web/20170404171927/http://www.seattletimes.com/seattle-news/transportation/sense-of-history-builds-as-tunnel-machine-bertha-inches-toward-daylight/ |archive-date=April 4, 2017 |url-status=live }}</ref> The boring machine was dismantled and removed from the site over the next four months.<ref>{{cite web|title=Alaskan Way Viaduct - Goodbye Bertha: Final piece of the tunneling machine removed from tunnel|url=http://www.wsdot.wa.gov/Projects/Viaduct/library/advisories-and-updates/goodbye-Bertha-removed|website=wsdot.wa.gov|publisher=WSDOT|access-date=December 15, 2017|archive-url=https://web.archive.org/web/20171215111212/http://www.wsdot.wa.gov/Projects/Viaduct/library/advisories-and-updates/goodbye-Bertha-removed|archive-date=December 15, 2017|url-status=live}}</ref>

Dirt produced by tunnel construction was sent to fill a CalPortland quarry in nearby Port Ludlow.<ref>{{cite web|url=http://www.wsdot.wa.gov/Projects/Viaduct/Contents/Item/Display/499|title=Where will the dirt from tunneling go?|publisher=WSDOT|archive-url=https://web.archive.org/web/20131219030645/http://www.wsdot.wa.gov/Projects/Viaduct/Contents/Item/Display/499|archive-date=December 19, 2013|url-status=live|access-date=December 26, 2013}}</ref> In July 2016, WSDOT estimated that the tunnel would be completed and open to traffic in early 2019. An estimated $223 million in cost overruns were reported as a result of the two-year stoppage.<ref name="Lindblom-Jul2016">{{cite news|url=http://www.seattletimes.com/seattle-news/berthas-woes-grind-on-more-delay-higher-cost-for-highway-99-tunnel/|title=Bertha's woes grind on: more delay, higher cost for Highway 99 tunnel|last=Lindblom|first=Mike|date=July 21, 2016|newspaper=The Seattle Times|access-date=July 21, 2016|archive-url=https://web.archive.org/web/20160722130447/http://www.seattletimes.com/seattle-news/berthas-woes-grind-on-more-delay-higher-cost-for-highway-99-tunnel/|archive-date=July 22, 2016|url-status=live}}</ref> The delay in construction caused by Bertha's stall cost the state government $60 million in extra costs that were granted by a budget increase from the legislature.<ref name="Times-Dec19"/> The damage to the tunnel boring machine itself was estimated at $642 million, which became the center of a legal dispute between WSDOT and STP.<ref name=court-january /><ref>{{cite web |last1=Mikkelsen |first1=Drew |title=Missing evidence questioned in trial over Seattle tunnel boring machine breakdown |url=https://www.king5.com/article/news/local/missing-evidence-questioned-in-trial-over-seattle-tunnel-boring-machine-breakdown/281-fb29e22d-0b40-4aed-84cb-20e15bfe6355 |publisher=KING 5 News |access-date=February 23, 2019 |date=January 9, 2019}}</ref> Fragments of the steel well casing struck in December 2013 and cited as a possible cause of Bertha's breakdown were stored as evidence at the construction site and subsequently went missing in 2014.<ref name="court-january">{{cite web |last1=Johnson |first1=Graham |title=Dispute over missing evidence in Bertha breakdown goes to court |url=https://www.kiro7.com/news/local/pipe-pieces-at-center-of-bertha-breakdown-lawsuit-are-missing/889084700 |publisher=KIRO 7 News |access-date=February 23, 2019 |date=January 9, 2019}}</ref><ref name=court-december18 /> Detailed journal entries kept by the tunnel contractor's deputy project manager between December 2013 and February 2014 also went missing.<ref name="court-december18">{{cite web |last1=Johnson |first1=Graham |title=Pipe pieces at center of Bertha breakdown lawsuit are missing |url=https://www.kiro7.com/news/local/pipe-pieces-at-center-of-bertha-breakdown-lawsuit-are-missing/889084700 |publisher=KIRO 7 News |access-date=February 23, 2019 |date=December 14, 2018}}</ref> In December 2019, a jury in Thurston County awarded $57.2 million in damages to WSDOT and found that the state government was not liable to cover STP's claimed repair costs of $300 million.<ref name="Times-Dec19">{{cite news |last=Lindblom |first=Mike |date=December 13, 2019 |title=Contractor ordered to pay Washington state $57M over tunnel-boring machine Bertha's big stall |url=https://www.seattletimes.com/seattle-news/transportation/contractor-ordered-to-pay-state-over-tunnel-boring-machine-berthas-big-stall/ |work=The Seattle Times |archive-url=https://web.archive.org/web/20221022194949/https://www.seattletimes.com/seattle-news/transportation/wsdot-notches-another-legal-win-over-highway-99-tunnel-cost-overruns-after-bertha-hit-pipe/ |archive-date=October 22, 2022 |access-date=December 13, 2019}}</ref>

==Opening and operations== thumb|right|The southbound lanes of the tunnel, seen during the opening celebration thumb|right|The north portal on opening day

Seattle Tunnel Partners announced that work was substantially complete on the tunnel in October 2018.<ref>{{cite news |date=November 1, 2018 |title=Seattle tunnel opening celebration set for February 2-3 |url=https://www.king5.com/article/news/local/seattle-tunnel/seattle-tunnel-opening-celebration-set-for-february-2-3/281-610130924 |publisher=KING 5 News |access-date=November 1, 2018}}</ref> The viaduct closed permanently on January 11, 2019.<ref>{{cite news|url=https://www.seattletimes.com/seattle-news/transportation/permanent-closure-of-alaskan-way-viaduct-delayed-until-january/|title=Permanent closure of Alaskan Way Viaduct delayed until January|last=Lindblom|first=Mike|date=September 17, 2018|work=The Seattle Times|access-date=September 18, 2018|archive-url=https://web.archive.org/web/20180917204001/https://www.seattletimes.com/seattle-news/transportation/permanent-closure-of-alaskan-way-viaduct-delayed-until-january/|archive-date=September 17, 2018|url-status=live}}</ref> Following the closure of the viaduct, sections of SR 99 were closed to traffic for three weeks to allow for the excavation of buried tunnel ramps at the north and south portals, as well as other preparations. The closure was widely expected to cause increased traffic congestion, and local government agencies responded by implementing expanded transit service and making other transportation changes to accommodate the displaced drivers. Despite the predicted traffic congestion, commute times for the Seattle area were not significantly above average, with many commuters opting for public transit, remote work, or bicycling to work.<ref>{{cite news |last=Gutman |first=David |date=January 24, 2019 |title='The cars just disappeared': What happened to the 90,000 cars a day the viaduct carried before it closed? |url=https://www.seattletimes.com/seattle-news/transportation/the-cars-just-disappeared-what-happened-to-the-90000-cars-a-day-the-viaduct-carried-before-it-closed/ |work=The Seattle Times |access-date=February 2, 2019}}</ref> thumb|Community celebration on the decommissioned Alaskan Way Viaduct during the opening On February 2, 2019, the downtown tunnel and sections of the viaduct and Battery Street Tunnel were opened to pedestrians as part of a community celebration and festival that was attended by 100,000 people. The celebrations included an 8K run, temporary art exhibits, food trucks, street performances, interactive exhibits, and an official ribbon-cutting ceremony.<ref>{{cite news |last=Gutman |first=David |date=February 2, 2019 |title='A huge achievement': Pedestrians swarm Seattle as viaduct comes down, tunnel set to open |url=https://www.seattletimes.com/seattle-news/transportation/tunnel-opening-goodbye-viaduct-festivities-feature-story/ |work=The Seattle Times |access-date=February 2, 2019}}</ref><ref>{{cite news |last1=Guevara |first1=Natalie |last2=Martin |first2=Genna |date=February 2, 2019 |title=Making history: Thousands gather to celebrate opening of new SR-99 tunnel |url=https://www.seattlepi.com/viaducttotunnel/article/Making-history-tunnel-opening-celebration-viaduct-13584666.php |work=Seattle Post-Intelligencer |access-date=February 2, 2019}}</ref> The following day, a bicycle race was held on the viaduct and in the new tunnel, with 12,000 participants.<ref>{{cite news |last=Sundell |first=Allison |date=February 2, 2019 |title=Thousands celebrate Seattle tunnel opening with weekend festivities |url=https://www.king5.com/article/news/local/tunnel-effect/thousands-celebrate-seattle-tunnel-opening-with-weekend-festivities/281-1427513f-46a8-40dd-8717-40ad18dbde8b |publisher=KING 5 News |access-date=February 4, 2019}}</ref> The state government also spent $4.4 million on billboards and advertisements on television and buses to market the new tunnel.<ref>{{cite news |last=Lindblom |first=Mike |date=January 24, 2019 |title=Washington state spending $4.4 million to market the Highway 99 tunnel |url=https://www.seattletimes.com/seattle-news/transportation/state-spending-4-4-million-to-market-the-highway-99-tunnel/ |work=The Seattle Times |access-date=March 3, 2019}}</ref>

The tunnel opened to northbound vehicular traffic at 11 p.m. on February 3 and southbound traffic at 12:15 a.m. on February 4.<ref>{{cite news |last=Sundell |first=Allison |date=February 4, 2019 |title=Seattle tunnel open to traffic both directions |url=https://www.king5.com/article/news/local/tunnel-effect/seattle-tunnel-open-to-traffic-both-directions/281-988a0911-2caa-403a-aa8f-dc9a98ab1820 |publisher=KING 5 News |access-date=February 4, 2019}}</ref> Other ramps and roads associated with the tunnel project, including an extension of Alaskan Way to Terminal 46 and the Harrison Street crossing were opened;<ref>{{cite news |date=February 4, 2019 |title=SR 99 tunnel now open to traffic |url=http://www.wsdot.wa.gov/Projects/Viaduct/library/advisories-and-updates/sr-99-tunnel-now-open-to-traffic |publisher=Washington State Department of Transportation |access-date=February 4, 2019}}</ref> the lone exception was the northbound offramp from SR 99 to Dearborn Street, which opened on February 19.<ref>{{cite news |last=Lindblom |first=Mike |date=February 18, 2019 |title=Highway 99's northbound offramp in Sodo opens Tuesday morning |url=https://www.seattletimes.com/seattle-news/transportation/highway-99s-northbound-offramp-in-sodo-opens-tuesday-morning/ |work=The Seattle Times |access-date=February 18, 2019}}</ref> The first full day of tunnel operations saw lower traffic volumes, with only 22,145 vehicle trips, due to an ongoing snowstorm, as well as confusion at the left-side exits.<ref>{{cite news |last=Lindblom |first=Mike |date=February 4, 2019 |title=Low traffic means an easy launch of the Highway 99 tunnel under Seattle |url=https://www.seattletimes.com/seattle-news/transportation/icy-aurora-leads-to-a-dry-highway-99-tunnel-on-opening-day/ |work=The Seattle Times |access-date=February 4, 2019}}</ref><ref>{{cite news |date=February 6, 2019 |title=Over 22,000 trips taken through Seattle's SR 99 tunnel on opening day |url=https://www.king5.com/article/news/local/tunnel-effect/over-22000-trips-taken-through-seattles-sr-99-tunnel-on-opening-day/281-552bb614-839c-439a-9b58-02d25f15b7fb |publisher=KING 5 News |access-date=February 6, 2019}}</ref> Within days, reports of smoke and haze within the tunnel prompted WSDOT to investigate possible faults in the exhaust ventilation system.<ref>{{cite news |last=Johnson |first=Graham |date=February 6, 2019 |title=WSDOT looking at systems in new SR 99 tunnel after smoke, haze |url=https://www.kiro7.com/news/local/wsdot-looking-at-systems-in-new-sr-99-tunnel-after-smoke-haze/915851039 |work=KIRO 7 News |access-date=February 6, 2019}}</ref> Within months of opening, tunnel usage had increased to over 70,000 trips per weekday and a weekly volume just under 500,000 trips by late March 2019.<ref>{{cite web |last1=Newborn |first1=Laura |title=How's traffic in Seattle's SR 99 tunnel? |url=https://wsdotblog.blogspot.com/2019/04/hows-traffic-in-seattles-sr-99-tunnel.html |website=WSDOT Blog |publisher=Washington State Department of Transportation |access-date=April 7, 2019 |date=April 5, 2019}}</ref><ref>{{cite news |last=Lindblom |first=Mike |date=May 14, 2019 |title=Traffic in new Highway 99 tunnel nearly matches last year's viaduct use |url=https://www.seattletimes.com/seattle-news/transportation/traffic-in-new-highway-99-tunnel-nearly-matches-last-years-viaduct-use/ |work=The Seattle Times |access-date=May 15, 2019}}</ref> Tolls were waived for the first few months of operations and began to be collected on November 9, 2019.<ref>{{cite news |date=January 30, 2019 |title=State Route 99 tunnel toll-free for first few months |url=https://www.king5.com/article/news/local/state-route-99-tunnel-toll-free-for-first-few-months/281-a16f6735-77c8-48da-b5b6-2d181d68f0d5 |publisher=KING 5 News |access-date=February 2, 2019}}</ref> WSDOT measured traffic before and after the start of tolling and reported a 26 percent decline in average weekday volumes in the tunnel, with no noticeable spike on nearby I-5.<ref>{{cite news |date=December 9, 2019 |title=What's happened to traffic since SR 99 tunnel tolling started |url=https://wsdotblog.blogspot.com/2019/12/traffic-since-sr-99-tolling-started.html |work=WSDOT Blog |publisher=Washington State Department of Transportation |access-date=December 18, 2019}}</ref> Higher volumes have been observed on Alaskan Way and other surface streets, especially during peak periods.<ref>{{cite news |last=Kostanich |first=Kara |date=November 20, 2019 |title=Where SR99 tunnel drivers are diverting to avoid the new toll |url=https://komonews.com/news/local/where-sr99-tunnel-drivers-are-diverting-to-avoid-the-new-toll |publisher=KOMO News |access-date=December 18, 2019}}</ref>

In 2019, WSDOT began filling in the Battery Street Tunnel, because the 1952 cut-and-cover tunnel did not meet modern safety standards, was expensive to maintain, and was made redundant by the Alaskan Way tunnel.<ref>{{cite web|url=http://www.wsdot.wa.gov/Projects/Viaduct/Contents/Item/Display/485|title=What will happen to the Battery Street Tunnel?|publisher=WSDOT|archive-url=https://web.archive.org/web/20131219025222/http://www.wsdot.wa.gov/Projects/Viaduct/Contents/Item/Display/485|archive-date=December 19, 2013|url-status=live|access-date=December 26, 2013}}</ref><ref>{{cite web| url=https://www.wsdot.wa.gov/Projects/Viaduct/battery | title=Filling and sealing the Battery Street Tunnel | publisher=WSDOT |url-status=dead |archive-url=https://web.archive.org/web/20191222122352/https://www.wsdot.wa.gov/Projects/Viaduct/battery |archive-date=December 22, 2019 |accessdate=August 25, 2025}}</ref>

The tunnel underwent several night closures in August 2025 to replace the worn lane surfaces with a new, textured concrete pavement through shot-blasting.<ref>{{cite news |last=Mellits |first=Mara |date=August 18, 2025 |title=Highway 99 tunnel closed as road repair begins |url=https://www.seattletimes.com/seattle-news/transportation/highway-99-tunnel-closed-tonight-as-road-repair-begins/ |work=The Seattle Times |accessdate=August 25, 2025}}</ref><ref>{{cite news |last=Dallas |first=Julia |date=August 20, 2025 |title=Northbound SR 99 tunnel closing Wednesday night |url=https://mynorthwest.com/chokepoints/northbound-sr-99-tunnel/4122636 |work=MyNorthwest |accessdate=August 25, 2025}}</ref>

==See also== * Big Dig, a cut‑and‑cover elevated‑to‑tunnel conversion of the formerly elevated Central Artery in Boston

==References== {{reflist |refs= <ref name="little dig">{{cite news |first=Greg |last=Howland, Jr |url=http://www.seattleweekly.com/2006-04-19/news/seattle-s-little-dig/ |title=Seattle's Little Dig |newspaper=Seattle Weekly |date=April 19, 2006 |access-date=December 8, 2012 |archive-url=https://web.archive.org/web/20150912162346/http://www.seattleweekly.com/2006-04-19/news/seattle-s-little-dig/ |archive-date=September 12, 2015 |url-status=dead }}</ref> }}

==Further reading== * {{cite news|first=Susan |last=Gilmore |url=http://seattletimes.nwsource.com/html/localnews/2003249507_webviaduct08.html |title=Two views of the viaduct |newspaper=The Seattle Times |date=September 8, 2006 |url-status=dead |archive-url=https://web.archive.org/web/20081204190949/http://seattletimes.nwsource.com/html/localnews/2003249507_webviaduct08.html |archive-date=December 4, 2008 }} * {{cite news|first=Susan |last=Gilmore |url=http://seattletimes.nwsource.com/html/localnews/2003185081_viaduct09m.html |title=State offers 3 decidedly different designs for viaduct |newspaper=The Seattle Times |date=August 9, 2006 |url-status=dead |archive-url=https://web.archive.org/web/20081204190340/http://seattletimes.nwsource.com/html/localnews/2003185081_viaduct09m.html |archive-date=December 4, 2008 }} * {{cite news|first=Susan |last=Gilmore |url=http://seattletimes.nwsource.com/html/localnews/2003169038_viaduct02m.html |title=Idea of fixing viaduct seen as having merit but problems as well |newspaper=The Seattle Times |date=August 2, 2006 |url-status=dead |archive-url=https://web.archive.org/web/20090814202721/http://seattletimes.nwsource.com/html/localnews/2003169038_viaduct02m.html |archive-date=August 14, 2009 }} * {{cite news|first=Susan |last=Gilmore |url=http://seattletimes.nwsource.com/html/localnews/2003149875_viaduct25m.html |title=What will happen if viaduct closes? Study takes a look |newspaper=The Seattle Times |date=July 25, 2006 |url-status=dead |archive-url=https://web.archive.org/web/20090814202716/http://seattletimes.nwsource.com/html/localnews/2003149875_viaduct25m.html |archive-date=August 14, 2009 }} * {{cite news |first=Larry |last=Lange |url=http://www.seattlepi.com/transportation/268857_viaduct03.html |title=A Longer shelf life for the viaduct |newspaper=Seattle Post-Intelligencer |date=May 3, 2006}}

==External links== {{Attached KML|display=title,inline}}

* {{Official website}} Alaskan Way Viaduct Replacement Program, from the Washington State Department of Transportation * {{YouTube|id=hvDhlSpfjC0|time=321|title=Engineering Careers in Tunnelling and Underground Space}}, ITA-AITES, June 6, 2012. This provides a view into the Earth-pressure-balanced TBM and Seattle-specific tunnel engineering issues. * {{cite web |title=Highways to Boulevards |website=Congress for the New Urbanism |date=2015-06-15 |url=https://www.cnu.org/highways-boulevards/campaign-cities/seattle |archive-url=https://web.archive.org/web/20190424012321/https://www.cnu.org/highways-boulevards/campaign-cities/seattle |archive-date=2019-04-24 |url-status=dead |access-date=2025-01-06}}

Category:2019 establishments in Washington (state) Category:Road tunnels in Washington (state) Category:Roads in Washington (state) Category:Tunnels completed in 2019 Category:Tunnels in Seattle Category:Viaducts in the United States