Evergreen Point Floating Bridge

{{Main|Evergreen Point Floating Bridge (1963)}}

The original Evergreen Point Floating Bridge, also named for state governor Albert D. Rosellini, opened on August 28, 1963, carrying the four-lane State Route 520 (at the time designated temporarily as the Evergreen Point branch of Primary State Highway 1 until the 1964 state highway renumbering).{{cite web |last=Dougherty |first=Phil |date=June 26, 2015 |title=Evergreen Point Floating Bridge opens on August 28, 1963. |url=http://www.historylink.org/index.cfm?DisplayPage=output.cfm&file_id=690 |work=HistoryLink |access-date=April 17, 2016 |archive-url=https://web.archive.org/web/20160413201937/http://www.historylink.org/index.cfm?DisplayPage=output.cfm&file_id=690 |archive-date=April 13, 2016 |url-status=live }} The {{convert|7,578|ft|m|adj=mid|-long}} floating span consisted of 33 pontoons and cost $24.7 million to construct (equivalent to ${{Formatprice|{{Inflation|US|24700000|1963}}}} in {{CURRENTYEAR}});{{Inflation-fn|US}} the bridge carried four lanes of traffic, separated by a curb that was later replaced with a simple Jersey barrier; at the center was a drawspan that opened for large vessels traversing the lake. The original bridge would also close to traffic during sustained wind gusts of {{convert|50|mph}} or higher for more than 15 minutes.

Due to increased traffic generated by rapid growth of the Eastside area, bridge replacement was explored as early as 1969, when building a parallel span was explored and rejected.{{cite news |date=December 16, 1969 |title=Highway Department: Commission Bars Traffic Study |page=E6 |work=The Seattle Times}} The Eastside is also served by the Interstate 90 floating bridges completed in 1940 and 1989, carrying traffic across Mercer Island to and from Bellevue.{{cite web |last=Lange |first=Greg |date=January 14, 1999 |title=Lake Washington Floating Bridge is dedicated on July 2, 1940 |url=http://www.historylink.org/File/682 |work=HistoryLink |access-date=March 19, 2017 |archive-url=https://web.archive.org/web/20170320144236/http://www.historylink.org/File/682 |archive-date=March 20, 2017 |url-status=live }}

The original Evergreen Point Floating Bridge was designed before the implementation of modern earthquake engineering standards, with vulnerabilities in its hollow support structures that could have failed in a major earthquake.{{cite news |last=Flores |first=Sergio |date=January 2017 |title=The Longest Floating Bridge: SR 520 |url=http://penpubinc.com/magazine/online/2017/AI/JanFeb/?page=66 |work=American Infrastructure |pages=66–70 |access-date=March 17, 2017 |archive-url=https://web.archive.org/web/20170321013717/http://penpubinc.com/magazine/online/2017/AI/JanFeb/?page=66 |archive-date=March 21, 2017 |url-status=live }}{{cite web |title=SR 520 Floating Bridge Replacement |url=http://www.geoengineers.com/project/sr-520-floating-bridge-replacement |publisher=GeoEngineers |access-date=March 17, 2017 |archive-url=https://web.archive.org/web/20170419195658/http://www.geoengineers.com/project/sr-520-floating-bridge-replacement |archive-date=April 19, 2017 |url-status=live }} Additionally, near the end of its lifetime, vibrations induced by storm surges and strong winds were able to compromise the aging drawspan, anchor cables, and pontoons, leading to structural failure in a major storm. Even if the storms were below the maximum threshold for failure to occur, Washington State Department of Transportation (WSDOT) would still close the floating bridge to traffic. Although the original bridge carried two lanes of traffic in each direction, it did not include shoulders or pedestrian and bicycle infrastructure. The lack of a shoulder led to traffic congestion in the event of an accident, which would block one or two lanes in a given direction and block emergency services from accessing the bridge.

Planning of the replacement bridge started in 1997 with a cross-lake study conducted by the state Department of Transportation.{{cite report |title=SR 520 Sustainability Report |date=January 2014 |publisher=Washington State Department of Transportation |pages=4, 7 |url=http://www.wsdot.wa.gov/NR/rdonlyres/81410031-4556-40D4-BD52-F51A69452188/0/2014_0122_SR520_SustainabilityReport_Final.pdf |access-date=April 17, 2016 |archive-url=https://web.archive.org/web/20170123035556/http://www.wsdot.wa.gov/NR/rdonlyres/81410031-4556-40D4-BD52-F51A69452188/0/2014_0122_SR520_SustainabilityReport_Final.pdf |archive-date=January 23, 2017 |url-status=dead }} The study followed several others in the late 20th century to find solutions to traffic on the SR 520 floating bridge, with most proposals rejected after heavy opposition from communities on both ends of the bridge.{{cite news |date=March 25, 1997 |title=Evergreen Point bridge solutions? |page=6 |work=Ellensburg Daily Record |url=https://news.google.com/newspapers?nid=860&dat=19970325&id=0gEfAAAAIBAJ&sjid=9coEAAAAIBAJ&pg=2433,4043702&hl=en |agency=Associated Press |via=Google News Archive |access-date=April 17, 2016}}

The preferred alternative for the bridge's design, with four general-purpose lanes and two HOV lanes, was announced by WSDOT in April 2010.{{cite news |last=Lindblom |first=Mike |date=April 28, 2010 |title=Seattle input alters Highway 520 bridge design |url=https://www.seattletimes.com/seattle-news/seattle-input-alters-highway-520-bridge-design/ |work=The Seattle Times |accessdate=October 29, 2024}} Alternative options included the construction of a southbound onramp from the I-5 express lanes, the addition of light rail to the project, and an eight-lane bridge.{{cite news |last=Lindblom |first=Mike |date=March 11, 2010 |title=New 520 bridge won't solve I-5 merge mess |url=https://www.seattletimes.com/seattle-news/new-520-bridge-wont-solve-i-5-merge-mess/ |work=The Seattle Times |accessdate=October 29, 2024}}{{cite news |last=Gaudette |first=Karen |date=April 27, 2005 |title=Group urges focus on 8-lane bridge |url=https://www.seattletimes.com/seattle-news/group-urges-focus-on-8-lane-bridge/ |work=The Seattle Times |accessdate=October 29, 2024}} The final environmental impact statement for the project was issued in 2011, allowing for construction of the pontoons to begin the following year.{{cite report |date=June 2011 |title=SR 520 Bridge Replacement and HOV Program: Final Environmental Impact Statement and Section 4(f) and 6(f) Evaluations |chapter=Executive Summary |chapter-url=http://www.wsdot.wa.gov/NR/rdonlyres/BF5FB36E-1BBD-46FA-81F2-5E37E54D840A/0/FEIS_ExecSummary.pdf |publisher=Washington State Department of Transportation |access-date=April 17, 2016 |archive-url=https://web.archive.org/web/20170123035619/http://www.wsdot.wa.gov/NR/rdonlyres/BF5FB36E-1BBD-46FA-81F2-5E37E54D840A/0/FEIS_ExecSummary.pdf |archive-date=January 23, 2017 |url-status=dead}}

Funding was allocated to major phases of the project at different times. The $4.5 billion in funding comes largely from the state gas tax earmarked for highways in 2005, toll revenue, and federal highway funds and loans. In 2014, the budget for the project was increased by $250 million to cover cost overruns.{{cite news |last=Lindblom |first=Mike |date=April 17, 2016 |title=Problems push 520 project over budget |url=http://www.seattletimes.com/seattle-news/problems-push-520-project-over-budget/ |work=The Seattle Times |access-date=April 17, 2016 |archive-url=https://web.archive.org/web/20160416015647/http://www.seattletimes.com/seattle-news/problems-push-520-project-over-budget/ |archive-date=April 16, 2016 |url-status=live }} The western portions of the project in Seattle, which are budgeted at $2 billion, were the last to be funded as part of the 2015 and 2022 legislative transportation packages.{{cite news |last=Kroman |first=David |date=November 16, 2023 |title=520 bridge contract delayed in hopes Legislature can cover cost hike |url=https://www.seattletimes.com/seattle-news/transportation/wsdot-delays-520-bridge-contract-hopes-legislature-can-cover-huge-cost-increase/ |work=The Seattle Times |accessdate=October 29, 2024}}

File:New 520 bridge August 2015 02 cropped.jpg

The first stage of the SR 520 floating bridge replacement project was the construction of 77 concrete pontoons in 2011 and 2012 by Kiewit-General-Manson at two purpose-built facilities in Aberdeen and Tacoma.{{cite web |title=Ten Years of SR 520 Bridge Project |url=http://www.shannonwilson.com/news/sr520 |publisher=Shannon & Wilson |access-date=March 17, 2017 |archive-url=https://web.archive.org/web/20170318084320/http://www.shannonwilson.com/news/sr520 |archive-date=March 18, 2017 |url-status=dead }} The pontoons were floated to the bridge on Lake Washington via the Lake Washington Ship Canal.{{cite web |title=Pontoon Tracking and Bridge Assembly |date=March 25, 2016 |publisher=Washington State Department of Transportation |url=http://www.wsdot.wa.gov/Projects/SR520Bridge/BridgeAndLandings/520bridgeassembly.htm |access-date=April 17, 2016|archive-url=https://web.archive.org/web/20160416072339/http://www.wsdot.wa.gov/Projects/SR520Bridge/BridgeAndLandings/520bridgeassembly.htm|archive-date=April 16, 2016|url-status=dead }}{{cite news |work=Popular Mechanics |date=November 11, 2011 |title=How to Build the World's Longest Floating Bridge |first=Tim |last=Newcomb |url=http://www.popularmechanics.com/technology/infrastructure/g666/how-to-build-the-worlds-longest-floating-bridge/?slide=2 |access-date=April 17, 2016|archive-url=https://web.archive.org/web/20160224024616/http://www.popularmechanics.com/technology/infrastructure/g666/how-to-build-the-worlds-longest-floating-bridge/?slide=2|archive-date=February 24, 2016|url-status=live }} Pontoon assembly and fastening, to form the floating bridge's deck, began in 2014 and concluded in July 2015.{{cite web |date=March 2015 |title=Pontoon construction complete for new floating bridge |url=http://www.wsdot.wa.gov/NR/rdonlyres/BBBF7CE8-D8E4-44E0-AF04-45A26B5ADC9C/0/2015_0300_PontoonFactSheet.pdf |publisher=Washington State Department of Transportation |access-date=April 17, 2016 |archive-url=https://web.archive.org/web/20170123035619/http://www.wsdot.wa.gov/NR/rdonlyres/BBBF7CE8-D8E4-44E0-AF04-45A26B5ADC9C/0/2015_0300_PontoonFactSheet.pdf |archive-date=January 23, 2017 |url-status=dead }}{{cite press release |date=July 8, 2015 |title=Get in line: Largest pontoons for new SR 520 floating bridge all in final position on Lake Washington |url=http://www.wsdot.wa.gov/News/2015/07/08_SR520PontoonMove.htm |publisher=Washington State Department of Transportation |access-date=April 17, 2016 |archive-url=https://web.archive.org/web/20160304055619/http://www.wsdot.wa.gov/News/2015/07/08_SR520PontoonMove.htm |archive-date=March 4, 2016 |url-status=live }}

In 2012, WSDOT identified cracks and other problems with the first batch of completed pontoons, estimating that it would cost $400 million to repair cracks and other flaws that would bring down the bridge's predicted lifespan below the desired 75 years.{{cite news |last=Douglas |first=C.R. |date=August 27, 2013 |title=520 Bridge pontoon problems could reach nearly $400 million |publisher=Q13 FOX News |access-date=May 12, 2016 |url=http://q13fox.com/2013/08/27/520-bridge-pontoon-problems-could-reach-nearly-400-million/ |archive-url=https://web.archive.org/web/20160605114811/http://q13fox.com/2013/08/27/520-bridge-pontoon-problems-could-reach-nearly-400-million/ |archive-date=June 5, 2016 |url-status=live }} The problems were originally speculated to stem from shortcuts allegedly taken by the contractor{{Citation needed|reason=Neither of the two citations at the end of this sentence mentions (or even hints at) mideeds by the contractors|date=October 2021}} to complete pontoons to meet set deadlines; the proposed solutions to fix the pontoons included adding high-tension steel cables and post-tensioning of the concrete.{{cite news |last=Lindblom |first=Mike |date=February 26, 2013 |title=State admits costly mistakes on 520 bridge |url=http://www.seattletimes.com/seattle-news/state-admits-costly-mistakes-on-520-bridge/ |work=The Seattle Times |access-date=April 17, 2016 |archive-url=https://web.archive.org/web/20160416015210/http://www.seattletimes.com/seattle-news/state-admits-costly-mistakes-on-520-bridge/ |archive-date=April 16, 2016 |url-status=live }} A state investigative report by concrete expert John Reilly blamed the WSDOT Bridge and Structures Office (BSO) for the error. The BSO did most of the pontoon design in-house, instead of delegating those details and the financial risk to contracting teams. The goal was to allow bids to be submitted sooner. The states top bridge engineer, Jugesh Kapur was ultimately let go over the error and another Department of Transportation employee was demoted.{{cite web | url=https://www.seattletimes.com/seattle-news/state-fires-top-bridge-engineer-over-520-pontoon-flaws/ | title=State fires top bridge engineer over 520 pontoon flaws | date=April 12, 2013 }} A floating, {{convert|660|ST|t|adj=mid}} cofferdam was launched in November 2013 to assist in repairs of the pontoons, functioning as a portable drydock that wrapped around parts of the pontoons.{{cite press release |date=November 22, 2013 |title=Drydock in the water: SR 520 coffer cell arrives on Lake Washington |url=http://www.wsdot.wa.gov/News/2013/11/22_SR520CofferCell.htm |publisher=Washington State Department of Transportation |access-date=April 20, 2016 |archive-url=https://web.archive.org/web/20160509150643/http://www.wsdot.wa.gov/News/2013/11/22_SR520CofferCell.htm |archive-date=May 9, 2016 |url-status=live }} The repairs were made by the contractor at the direction of WSDOT from December 2013 to June 2014 and cost a total of approximately $208 million,{{cite news |last=Vedder |first=Tracy |date=February 28, 2014 |title=More woes plague SR-520 Bridge project |url=http://komonews.com/archive/more-woes-plague-sr-520-bridge-project |publisher=KOMO 4 News |access-date=April 20, 2016 |archive-url=https://web.archive.org/web/20160508070058/http://komonews.com/archive/more-woes-plague-sr-520-bridge-project |archive-date=May 8, 2016 |url-status=live }} using up the majority of the program's reserve funds.{{cite web |title=SR 520 – Pontoon Modifications |url=http://www.wsdot.wa.gov/Projects/SR520Bridge/Library/PontoonMods.htm |publisher=Washington State Department of Transportation |access-date=April 20, 2016 |archive-url=https://web.archive.org/web/20160421035559/http://www.wsdot.wa.gov/Projects/SR520Bridge/Library/PontoonMods.htm |archive-date=April 21, 2016 |url-status=live }}{{cite press release |date=January 8, 2014 |title=WSDOT executes new SR 520 pontoon change order |url=http://www.wsdot.wa.gov/News/2014/01/SR520PontoonChangeOrder01082014.htm |publisher=Washington State Department of Transportation |access-date=April 20, 2016 |archive-url=https://web.archive.org/web/20160509132825/http://www.wsdot.wa.gov/News/2014/01/SR520PontoonChangeOrder01082014.htm |archive-date=May 9, 2016 |url-status=live }} As a result of the pontoon issues, the estimated opening of the bridge was pushed back from December 2014 into 2016.

Construction of the bridge deck, beginning with the eastern approach in Medina, began in March 2012.{{cite news |last=Lindblom |first=Mike |date=March 28, 2012 |title=Modern design, retro touches: Here comes the new 520 bridge |url=http://www.seattletimes.com/seattle-news/modern-design-retro-touches-here-comes-the-new-520-bridge/ |work=The Seattle Times |access-date=April 17, 2016 |archive-url=https://web.archive.org/web/20160422091239/http://www.seattletimes.com/seattle-news/modern-design-retro-touches-here-comes-the-new-520-bridge/ |archive-date=April 22, 2016 |url-status=live }} In March 2015, two construction accidents on the bridge slowed construction for reevaluation of safety measures: a contractor was killed after a high fall on the east highrise; and a crane-lifted load of steel pipes swung out of control into a King County Metro bus and an overhead highway sign.{{cite news |last1=Lindblom |first1=Mike |last2=Cornwell |first2=Paige |date=March 18, 2015 |title=520 bridge incidents prompt extra safety training around state |url=http://www.seattletimes.com/seattle-news/transportation/road-project-crews-to-get-extra-safety-training/ |work=The Seattle Times |access-date=April 17, 2016 |archive-url=https://web.archive.org/web/20160416015505/http://www.seattletimes.com/seattle-news/transportation/road-project-crews-to-get-extra-safety-training/ |archive-date=April 16, 2016 |url-status=live }}

The bridge deck was lifted into place in August 2015,{{cite news |last=Lindblom |first=Mike |date=August 23, 2015 |title=Road-deck milestone for new 520 bridge |url=http://www.seattletimes.com/seattle-news/transportation/road-deck-milestone-for-new-520-bridge/ |work=The Seattle Times |access-date=April 17, 2016 |archive-url=https://web.archive.org/web/20160714182919/http://www.seattletimes.com/seattle-news/transportation/road-deck-milestone-for-new-520-bridge/ |archive-date=July 14, 2016 |url-status=live }} and the final concrete pour was finished in October 2015, completing the bridge deck.{{cite news |last=Morse-Miller |first=Haylee |date=October 27, 2015 |title=State's newest floating bridge now all decked out |url=http://wsdotblog.blogspot.com/2015/10/states-newest-floating-bridge-now-all.html |work=The WSDOT Blog |publisher=Washington State Department of Transportation |access-date=April 17, 2016 |archive-url=https://web.archive.org/web/20160304215143/http://wsdotblog.blogspot.com/2015/10/states-newest-floating-bridge-now-all.html |archive-date=March 4, 2016 |url-status=live }}

File:Evergreen Point Floating Bridge eastbound from HOV lane.jpg

The new bridge was dedicated on April 2, 2016, in a ceremony presided over by Governor of Washington Jay Inslee and attended by an estimated 40,000 to 50,000 people.{{cite news |last=Lindblom |first=Mike |date=November 1, 2018 |title=Goodbye viaduct, hello tunnel: WSDOT plans a celebration of the old and new Feb. 2-3 |url=https://www.seattletimes.com/seattle-news/transportation/goodbye-viaduct-hello-tunnel-wsdot-plans-a-celebration-of-the-old-and-new-feb-2-3/ |work=The Seattle Times |access-date=November 1, 2018}} The ceremony also included a community fun run and walk on the bridge, and a bicycle ride hosted by the Cascade Bicycle Club on the bridge and the Interstate 5 express lanes the following day.{{cite press release |last=Peer |first=Steve |date=January 12, 2016 |title=April grand opening celebration announced for SR 520's new floating bridge |url=http://www.wsdot.wa.gov/News/2016/01/12_520GrandOpeningCelebration.htm |publisher=Washington State Department of Transportation |access-date=April 17, 2016 |archive-url=https://web.archive.org/web/20160417084334/http://www.wsdot.wa.gov/News/2016/01/12_520GrandOpeningCelebration.htm |archive-date=April 17, 2016 |url-status=dead }} As part of the opening ceremonies, the bridge was certified as the world's longest floating bridge by Guinness World Records, at {{convert|7,708.49|ft|m}} long;{{cite web |title=Longest bridge, floating bridge |url=http://www.guinnessworldrecords.com/world-records/69091-longest-bridge-floating-bridge |publisher=Guinness World Records |access-date=April 17, 2016 |archive-url=https://web.archive.org/web/20160630220710/http://www.guinnessworldrecords.com/world-records/69091-longest-bridge-floating-bridge |archive-date=June 30, 2016 |url-status=live }} the bridge took the record from the previous Evergreen Point Floating Bridge, which was {{convert|130|ft|m}} shorter in length.{{cite news |last=Demay |first=Daniel |date=April 2, 2016 |title=Thousands cross new 520 Bridge – on foot |url=http://www.seattlepi.com/local/transportation/article/Photos-New-520-bridge-finally-opens-to-foot-7223377.php |work=Seattle Post-Intelligencer |access-date=May 11, 2016 |archive-url=https://web.archive.org/web/20160512175323/http://www.seattlepi.com/local/transportation/article/Photos-New-520-bridge-finally-opens-to-foot-7223377.php |archive-date=May 12, 2016 |url-status=live }}

Traffic on the new bridge was shifted over in two stages, beginning with westbound traffic on April 11 and ending with eastbound traffic on April 25.{{cite news |last=Lindblom |first=Mike |date=January 12, 2016 |title=New 520 bridge to open in April; walkers, bicyclists get to try it first |url=http://www.seattletimes.com/seattle-news/transportation/new-520-bridge-to-open-in-april-walkers-bikes-will-get-to-try-it-first/ |work=The Seattle Times |access-date=April 17, 2016 |archive-url=https://web.archive.org/web/20160407115057/http://www.seattletimes.com/seattle-news/transportation/new-520-bridge-to-open-in-april-walkers-bikes-will-get-to-try-it-first/ |archive-date=April 7, 2016 |url-status=live }}{{cite web |title=Traffic switch from old SR 520 floating bridge to new bridge |url=http://www.wsdot.wa.gov/NR/rdonlyres/F8E05309-7D6F-4A83-801F-A69BB5369D51/0/2016_FBL_TrafficSwitch_Overview.pdf |date=January 2016 |publisher=Washington State Department of Transportation |access-date=April 20, 2016 |archive-url=https://web.archive.org/web/20160417205923/http://www.wsdot.wa.gov/NR/rdonlyres/F8E05309-7D6F-4A83-801F-A69BB5369D51/0/2016_FBL_TrafficSwitch_Overview.pdf |archive-date=April 17, 2016 |url-status=dead }} Initially, the bridge narrowed from 6 lanes to 4 lanes at the end of the floating span, over {{convert|1.2|mi|km}} east of the Montlake Boulevard interchange, and was not fully traversable for bicyclists and pedestrians.{{cite web |title=Building the West Approach Bridge North |date=August 2015 |url=http://www.wsdot.wa.gov/NR/rdonlyres/87A80F45-1111-40AB-9E19-E5FD179AAD3B/0/SR520_WestApproachBridgeNorth_Folio.pdf |publisher=Washington State Department of Transportation |access-date=April 17, 2016 |archive-url=https://web.archive.org/web/20160509141028/http://www.wsdot.wa.gov/NR/rdonlyres/87A80F45-1111-40AB-9E19-E5FD179AAD3B/0/SR520_WestApproachBridgeNorth_Folio.pdf |archive-date=May 9, 2016 |url-status=dead }} Shortly after the opening of the bridge's westbound lanes, the Washington State Transportation Commission proposed increasing toll rates to introduce nighttime tolling by 2017.{{cite news |last=Burton |first=Lynsi |date=April 11, 2016 |title=State proposes 520 Bridge toll hikes |url=http://www.seattlepi.com/local/transportation/article/State-proposes-520-Bridge-toll-hikes-7241479.php |work=Seattle Post-Intelligencer |access-date=April 17, 2016 |archive-url=https://web.archive.org/web/20160416200521/http://www.seattlepi.com/local/transportation/article/State-proposes-520-Bridge-toll-hikes-7241479.php |archive-date=April 16, 2016 |url-status=live }} The toll rate increase and nighttime toll was approved by the commission and implemented on July 1, 2017.{{cite news |date=June 19, 2017 |title=SR 520 Bridge toll rates increase |url=http://www.rentonreporter.com/news/sr-520-bridge-toll-rates-increase/ |work=Redmond Reporter |access-date=April 11, 2018 |archive-url=https://web.archive.org/web/20180412082607/http://www.rentonreporter.com/news/sr-520-bridge-toll-rates-increase/ |archive-date=April 12, 2018 |url-status=live }}

The old bridge was planned to be decommissioned by floating away pontoons to an industrial site in Kenmore for disposal and recycling;{{cite web |title=SR 520 – Floating Bridge and Landings Project: Kenmore Industrial Park |url=http://www.wsdot.wa.gov/Projects/SR520Bridge/BridgeAndLandings/KenmoreIndPrk.htm |publisher=Washington State Department of Transportation |access-date=April 20, 2016 |archive-url=https://web.archive.org/web/20160421040644/http://www.wsdot.wa.gov/Projects/SR520Bridge/BridgeAndLandings/KenmoreIndPrk.htm |archive-date=April 21, 2016 |url-status=dead }} in March 2016, the city rejected the plan, citing the possible release of toxins in the pontoon's concrete.{{cite news |last=Graf |first=Heather |date=March 31, 2016 |title=Kenmore says no to 520 bridge deconstruction |url=http://www.king5.com/news/local/kenmore-refuses-to-allow-520-bridge-deconstruction/111384620 |publisher=KING 5 News |access-date=April 17, 2016 |archive-url=https://web.archive.org/web/20160414202334/http://www.king5.com/news/local/kenmore-refuses-to-allow-520-bridge-deconstruction/111384620 |archive-date=April 14, 2016 |url-status=live }} The pontoons were sold to a recycling company based in Gig Harbor which plans to reuse the individual pontoons for floating decks and other projects.{{cite news |last=Langler |first=John |date=March 31, 2016 |title=Company buys 520 bridge pontoons, plans to recycle worldwide |url=http://www.king5.com/news/local/company-buys-all-sr-520-pontoons-plans-to-recycle-worldwide/113050517 |publisher=KING 5 News |access-date=April 17, 2016 |archive-url=https://web.archive.org/web/20160413070719/http://www.king5.com/news/local/company-buys-all-sr-520-pontoons-plans-to-recycle-worldwide/113050517 |archive-date=April 13, 2016 |url-status=live }} An unaffiliated contest was held in 2012 seeking ideas for the 33 pontoons of the old bridge, with solutions ranging from a "floating High Line" to partial submersion for walking paths.{{cite news |last=Gutierrez |first=Scott |date=September 23, 2012 |title=What to do with the old 520 Bridge pontoons? |url=http://www.seattlepi.com/local/transportation/article/520-3887734.php |work=Seattle Post-Intelligencer |access-date=April 17, 2016 |archive-url=https://web.archive.org/web/20160513033220/http://www.seattlepi.com/local/transportation/article/520-3887734.php |archive-date=May 13, 2016 |url-status=live }} The first pontoon of the old bridge to be disassembled was towed through the Lake Washington Ship Canal in July 2016.{{cite press release |date=July 20, 2016 |title=So long: first pontoon from the old SR 520 bridge floating out of Lake Washington |url=http://www.wsdot.wa.gov/news/2016/07/20/so-long-first-pontoon-old-sr-520-bridge-floating-out-lake-washington |publisher=Washington State Department of Transportation |access-date=July 31, 2016 |archive-url=https://web.archive.org/web/20160724133023/http://www.wsdot.wa.gov/news/2016/07/20/so-long-first-pontoon-old-sr-520-bridge-floating-out-lake-washington |archive-date=July 24, 2016 |url-status=live }} As of December 2020, several pontoons of the old bridge are anchored in the Pitt River in Pitt Meadows, British Columbia.{{cite news |last=Melnychuk |first=Phil |date=October 31, 2016 |title=Bridge from afar moored in Pitt Meadows |url=https://www.mapleridgenews.com/news/bridge-from-afar-moored-in-pitt-meadows/ |work=Maple Ridge-Pitt Meadows News |access-date=December 28, 2020}}

Construction of the {{convert|1.2|mi|km|adj=mid}} western approach to the floating bridge, a conventional viaduct that crosses Union Bay, was split into three projects. A temporary bridge to connect the new floating bridge to the existing western approach was completed in September 2014.{{cite web |title=SR 520 Bridge Program: West Connection Bridge |url=http://www.wsdot.wa.gov/Projects/SR520Bridge/BridgeAndLandings/520_wcb.htm |publisher=Washington State Department of Transportation |url-status=dead |archive-url=https://web.archive.org/web/20150101181326/http://www.wsdot.wa.gov/Projects/SR520Bridge/BridgeAndLandings/520_wcb.htm |archive-date=January 1, 2015 |accessdate=October 29, 2024}} The north side of the new western approach, which would ultimately carry westbound traffic and the multi-use trail, began construction in October 2014.{{cite press release |date=October 15, 2024 |title=SR 520 construction breaks ground with Seattle ramp demolition |url=http://www.wsdot.wa.gov/News/2014/10/15_SR520WabnGroundbreaking.htm |publisher=Washington State Department of Transportation |url-status=dead |archive-url=https://web.archive.org/web/20150119030019/http://www.wsdot.wa.gov/News/2014/10/15_SR520WabnGroundbreaking.htm |archive-date=January 19, 2015 |accessdate=October 29, 2024}} The project included removal of unused ramps over SR 520 that were built in the 1960s for the cancelled R.H. Thomson Expressway project;{{cite news |last=Metcalfe |first=John |date=July 18, 2014 |title=A Doomed Seattle Freeway Ramp Gets a Loving Goodbye |url=https://www.bloomberg.com/news/articles/2014-07-18/a-doomed-seattle-freeway-ramp-gets-a-loving-goodbye |work=CityLab |accessdate=October 29, 2024}} the ramps were demolished the following month, with the exception of a single set of four columns preserved for a future park, to make way for a work platform.{{cite news |date=November 13, 2014 |title=520 closing again for demolition on ramps |url=https://www.djc.com/news/co/12071859.html |work=Seattle Daily Journal of Commerce |accessdate=October 29, 2024}}{{cite news |last=Lindblom |first=Mike |date=June 3, 2024 |title=Seattle's famous 'ramps to nowhere' on the way to becoming a park |url=https://www.seattletimes.com/seattle-news/transportation/seattles-famous-ramps-to-nowhere-on-the-way-to-becoming-a-park/ |work=The Seattle Times |accessdate=October 29, 2024}} The new approach bridge opened for westbound traffic in August 2017, with later revisions to extend the HOV lane towards the Montlake interchange.{{cite news |last=DeMay |first=Daniel |date=August 25, 2017 |title=SR 520 bridge closed this weekend |url=http://www.seattlepi.com/local/transportation/article/SR-520-bridge-closed-this-weekend-11958385.php |work=Seattle Post-Intelligencer |access-date=December 1, 2017 |archive-url=https://web.archive.org/web/20171201233341/http://www.seattlepi.com/local/transportation/article/SR-520-bridge-closed-this-weekend-11958385.php |archive-date=December 1, 2017 |url-status=live }}{{cite news |last=Selvey |first=Ashley |date=August 23, 2017 |title=SR 520 Westbound: Straight ahead |url=https://wsdotblog.blogspot.com/2017/08/sr-520-westbound-straight-ahead.html |work=WDSOT Blog |url-status=dead |archive-url=https://web.archive.org/web/20190114025434/https://wsdotblog.blogspot.com/2017/08/sr-520-westbound-straight-ahead.html |archive-date=January 14, 2019 |accessdate=October 29, 2024}} The bridge's multi-use bike and pedestrian path partially opened in July 2016, with access to the completed sections for an "out-and-back" experience;{{cite news |last=Chen |first=Natascha |date=July 22, 2016 |title=Bike/pedestrian path opening on SR 520 Bridge |url=http://www.kiro7.com/news/local/bikepedestrian-path-opening-on-sr-520-bridge/409451835 |publisher=KIRO 7 News |access-date=July 31, 2016 |archive-url=https://web.archive.org/web/20160724223449/http://www.kiro7.com/news/local/bikepedestrian-path-opening-on-sr-520-bridge/409451835 |archive-date=July 24, 2016 |url-status=live }} the trail was fully opened on December 20, 2017.{{cite news |date=December 20, 2017 |title=WSDOT opens new bike/pedestrian trail on SR 520 bridge |url=http://www.king5.com/article/news/local/wsdot-opens-new-bikepedestrian-trail-on-sr-520-bridge/281-501188946 |publisher=KING 5 News |access-date=April 11, 2018 |archive-url=https://web.archive.org/web/20171221004548/http://www.king5.com/article/news/local/wsdot-opens-new-bikepedestrian-trail-on-sr-520-bridge/281-501188946 |archive-date=December 21, 2017 |url-status=live }}

The original approach bridge continued to carry eastbound traffic until it was closed in November 2019 to prepare for construction of the south half of the new approach bridge. All four lanes of traffic between Montlake Boulevard and the floating bridge was directed onto the westbound approach bridge, which was narrowed and restriped for the multi-year construction period.{{cite press release |date=November 6, 2019 |title=Eastbound SR 520 in Seattle closed Nov. 9-10 weekend to reduce highway to two lanes |url=https://www.wsdot.wa.gov/news/2019/11/06/eastbound-sr-520-seattle-closed-nov-9-10-weekend-reduce-highway-two-lanes |publisher=Washington State Department of Transportation |url-status=dead |archive-url=https://web.archive.org/web/20200811132740/https://www.wsdot.wa.gov/news/2019/11/06/eastbound-sr-520-seattle-closed-nov-9-10-weekend-reduce-highway-two-lanes |archive-date=August 11, 2020 |accessdate=October 29, 2024}}{{cite news |last=Robertson |first=Kipp |date=October 21, 2019 |title=3-year lane closure on SR 520 likely to cause additional delays |url=https://www.king5.com/article/traffic/520-lane-closure-three-years/281-e5256cce-b1bd-4010-9eae-ef770762e7c2 |publisher=KING 5 News |accessdate=October 29, 2024}} A temporary onramp from Lake Washington Boulevard was opened a month later to replace the last of the unused Thomson Expressway ramps.{{cite news |date=December 17, 2019 |title=New temporary eastbound SR 520 on-ramp open for traffic |url=https://www.king5.com/article/traffic/traffic-news/sr-520-eastbound-on-ramp-changes-december/281-b8c285b0-272a-4234-a0d6-cbd18fcf32eb |publisher=KING 5 News |accessdate=October 29, 2024}} Two mobile gantry cranes were used to disassemble and lift pieces of the old approach bridge beginning in 2020 after a construction delay due to the COVID-19 pandemic.{{cite news |last=Minnick |first=Benjamin |date=April 1, 2024 |title=Gantry cranes roll in next to SR 520 floating bridge |url=https://www.djc.com/news/co/12130965.html |work=Seattle Daily Journal of Commerce |accessdate=October 29, 2024}} The eastbound lanes on the approach bridge were opened to limited traffic in July 2023 and expanded to carry three lanes in its permanent configuration the following month.{{cite news |last=Peer |first=Steve |date=July 24, 2023 |title=New day, new way in Seattle's Montlake neighborhood |url=https://wsdotblog.blogspot.com/2023/07/new-day-new-way-montlake.html |work=WSDOT Blog |publisher=Washington State Department of Transportation |accessdate=October 29, 2024}}{{cite news |last=Phaysith |first=Nicole |date=September 14, 2023 |title=SR 520's Montlake Project: Summer steps forward, fall closures ahead |url=https://wsdotblog.blogspot.com/2023/09/sr-520-montlake-project.html |work=WSDOT Blog |publisher=Washington State Department of Transportation |accessdate=October 29, 2024}} The remainder of the SR 520 megaproject, which includes replacement of the Portage Bay bridge and Montlake Boulevard interchange, is scheduled to be completed in 2031.{{cite news |date=April 4, 2024 |title=Skanska inks $1.4B contract for new Portage Bay Bridge |url=https://www.djc.com/news/co/12163106.html |work=Seattle Daily Journal of Commerce |url-access=subscription |accessdate=May 4, 2024}}

The new Evergreen Point Floating Bridge was designed to be more stable in stronger winds and raised the bridge deck much higher above the surface of the lake than the old bridge. Unlike the original floating bridge, where the road surface is directly on pontoons connected end-to-end, the new bridge featured pontoons laid north–south, perpendicular to the direction of vehicular traffic, and a road surface on a platform raised {{convert|20|ft|m}} above the water.{{cite web |title=SR 520 – Floating Bridge Facts |url=http://www.wsdot.wa.gov/Projects/SR520Bridge/About/BridgeFacts.htm |publisher=Washington State Department of Transportation |access-date=April 17, 2016 |archive-url=https://web.archive.org/web/20160423222030/http://www.wsdot.wa.gov/Projects/SR520Bridge/About/BridgeFacts.htm |archive-date=April 23, 2016 |url-status=live }} This design includes shoulders and a protected pedestrian and bicycle path across the viaduct.

The floating bridge is laid atop 77 concrete pontoons that float above the water and are secured by 58 anchors to the lake bottom.{{cite web |title=SR 520 – Floating Bridge and Landings Project: Construction Overview |url=http://www.wsdot.wa.gov/Projects/SR520Bridge/BridgeAndLandings/StepByStep.htm |publisher=Washington State Department of Transportation |access-date=April 20, 2016 |archive-url=https://web.archive.org/web/20160421041247/http://www.wsdot.wa.gov/Projects/SR520Bridge/BridgeAndLandings/StepByStep.htm |archive-date=April 21, 2016 |url-status=dead }}

Of the pontoons, 21 are longitudinal pontoons that support the deck and structure and are {{convert|360|x|75|x|28|ft}} and weigh {{convert|11,000|ST|t}}; 54 smaller supplemental pontoons, weighing {{convert|2,500|ST|t}}, are used to stabilize the weight of the bridge; and two "cross" pontoons, weighing {{convert|10,100|ST|t}}, are sited at each end of the floating span at transitional spans, which connect the deck to fixed bridges and approaches using hinges to move up to {{convert|24|in|cm}} for fluctuations in lake water levels moving the pontoons. All the pontoons are designed with watertight compartments that are monitored remotely with sensors to detect leaks that could lead to catastrophic failure.{{cite news |last=Peer |first=Steve |date=April 14, 2016 |title=How much do you know about the new 520 bridge? |url=http://www.djc.com/news/co/12088246.html |work=Seattle Daily Journal of Commerce |access-date=April 20, 2016 |archive-url=https://web.archive.org/web/20160421042658/http://www.djc.com/news/co/12088246.html |archive-date=April 21, 2016 |url-status=live }}

The bridge's 58 anchors all feature {{convert|3|in|cm|adj=mid|-thick}}, {{convert|1,000|ft|m|adj=mid|-long}} steel cables and are divided into three types: 45 {{convert|587|ST|t|adj=mid}} fluke anchors used in softer soils deep in the lakebed; eight {{convert|107|ST|t|adj=mid}} gravity anchors used in solid soils nearer to the shore; and five {{convert|10|ft|m|adj=mid|-diameter}}, {{convert|79 to 92|ft|m|adj=mid|-long}} drilled shaft anchors used in conjunction with the gravity anchors to prevent navigation hazards.{{cite news |last=Marshall |first=Aarian |date=April 19, 2016 |title=What It Takes to Keep a 7,700-Foot Floating Bridge From Doom |url=https://www.wired.com/2016/04/takes-keep-7700-foot-floating-bridge-doom/ |work=Wired.com |access-date=April 20, 2016 |archive-url=https://web.archive.org/web/20160420112418/http://www.wired.com/2016/04/takes-keep-7700-foot-floating-bridge-doom/ |archive-date=April 20, 2016 |url-status=live }}

To ensure storm resistance in the event of water seeping into the pontoons, each pontoon is outfitted with a leak detection system with a float switch that sits about {{convert|3|in|cm}} off the floor. If the pontoon is breached, an alarm will sound inside the maintenance building. From there, a pump can be lowered into the chamber and controlled from the deck above.

The bridge deck is made of 776 precast concrete sections that are elevated {{convert|20|ft|m}} above the concrete pontoons that forms the lower deck which essentially creates "a bridge on top of a bridge". Unlike the older bridge, maintenance vehicles can now access the pontoons from beneath the upper roadway deck without interrupting traffic. According to a project engineer on the site, the deck had to be structurally isolated from the main support structure using a damping system to ensure seismic resistance up to a magnitude 9 earthquake to comply with local building codes. The original deck design called for three support columns but was later revised to two due to aesthetic issues. Moreover, the lighting mounted on top of the deck had to be positioned to minimize light pollution as well as its effect on aquatic habitat.

{{wide image|Seattle - SR520 from south pano 01.jpg|1200px|Panoramic view of the bridge looking north from Madison Park, Seattle. The western approach is split between the original low-level roadway for eastbound traffic and a high-level viaduct for westbound traffic, bicyclists, and pedestrians. The land straight ahead past the bridge is Laurelhurst.}}

The bridge has two general purpose lanes and one high-occupancy vehicle lane (HOV lane) per direction. It includes shoulders and a {{convert|14|ft|m|adj=mid|-wide}} pedestrian/bicycle path on the north side, unlike the 1963 bridge. Congestion on the old bridge was blamed on lack of shoulders, where disabled vehicles would cause severe backups.{{cite news |title=Working toward consensus on a new 520 floating bridge |first=Mark A. |last=Emmert |date=June 19, 2007 |work=The Seattle Times |url=http://www.seattletimes.com/opinion/working-toward-consensus-on-a-new-520-floating-bridge/ |access-date=April 17, 2016|archive-url=https://web.archive.org/web/20170123035613/http://www.seattletimes.com/opinion/working-toward-consensus-on-a-new-520-floating-bridge/|archive-date=January 23, 2017|url-status=live }}

{{anchor|Sentinels}}Ornamental elements include four sentinel towers rising {{convert|43|ft|m}} above the bridge deck at the approaches, and belvederes on the north side.{{cite news |title=Construction to begin on new 520 bridge |last=Gutierrez |first=Scott |date=March 29, 2012 |work=Seattle Post-Intelligencer |url=http://www.seattlepi.com/local/transportation/article/Construction-to-start-on-the-new-520-floating-3441908.php |access-date=April 17, 2016|archive-url=https://web.archive.org/web/20160508074129/http://www.seattlepi.com/local/transportation/article/Construction-to-start-on-the-new-520-floating-3441908.php|archive-date=May 8, 2016|url-status=live }}

The bridge features advanced monitoring devices and new maintenance facilities. Beneath the bridge is a three-story high brick building used to control and monitor various life support and utility systems on the bridge.{{cite news |last=Schlosser |first=Kurt |date=March 30, 2016 |title=Inside the world's longest floating bridge: How engineers made Seattle's new Lake Washington span bigger, better and safer |url=http://www.geekwire.com/2016/behind-scenes-520-floating-bridge/ |work=GeekWire |access-date=March 17, 2017 |archive-url=https://web.archive.org/web/20170318000303/http://www.geekwire.com/2016/behind-scenes-520-floating-bridge/ |archive-date=March 18, 2017 |url-status=live }} A backup generator sits on the ground level to power all systems in case of power loss. Behind the back wall of the building lies a massive retaining wall built in response to steep hills.

In 2023, the floating bridge carried an annual average of 57,913 vehicles per weekday. Prior to the COVID-19 pandemic, the bridge carried a weekday average of 74,912 vehicles in 2018.{{cite web |title=Traffic Count (TCDS) |url=https://wsdot.public.ms2soft.com/tcds/tsearch.asp?loc=Wsdot&mod=TCDS |publisher=Washington State Department of Transportation |accessdate=October 29, 2024}}

Public transportation and high-occupancy vehicle (HOV) use were incorporated in the bridge design. The bridge includes HOV lanes with priority for transit and the program as a whole built several transit-only facilities. A 2008 WSDOT report included five core bus rapid transit routes proposed by Sound Transit connecting the Eastside (Kirkland, Redmond, and Bellevue) to Downtown Seattle and the University District, with a base frequency of 15 minutes, increasing up to 7 minutes at peak times.{{cite report |author1=Washington State Department of Transportation |author2=Sound Transit |author3=King County Metro |date=December 31, 2008 |title=State Route 520 High Capacity Transit Plan |pages=25–30 |url=http://www.wsdot.wa.gov/NR/rdonlyres/D329E6C5-BF91-4EAC-8B95-9D58A2B498F6/0/Final_HCTP.pdf |publisher=Washington State Department of Transportation |access-date=April 17, 2016 |archive-url=https://web.archive.org/web/20160304140749/http://www.wsdot.wa.gov/NR/rdonlyres/D329E6C5-BF91-4EAC-8B95-9D58A2B498F6/0/Final_HCTP.pdf |archive-date=March 4, 2016 |url-status=dead }} The bus rapid transit program was not implemented and replaced by increased frequency on King County Metro and Sound Transit Express routes that serve the corridor.{{cite news |last=Lindblom |first=Mike |date=September 26, 2018 |title=I-5 will add a fifth express lane to serve future Eastside-South Lake Union bus routes |url=https://www.seattletimes.com/seattle-news/transportation/i-5-will-add-a-5th-express-lane-to-serve-future-eastside-south-lake-union-bus-routes/ |work=The Seattle Times |accessdate=October 29, 2024}} Existing freeway bus stations (also known as "flyer stops") on the Eastside at Evergreen Point and Yarrow Point were rebuilt and moved from the freeway's shoulder to the median, accompanied by landscaped lids with parking and lawns, in 2014 for increased compatibility with the bridge's planned HOV lanes.{{cite news |last=Lindblom |first=Mike |date=June 15, 2014 |title=Evergreen Point transit station opens Monday |url=http://blogs.seattletimes.com/today/2014/06/evergreen-point-transit-station-opens-monday/ |work=The Seattle Times |access-date=April 17, 2016 |archive-url=https://web.archive.org/web/20170902133624/http://blogs.seattletimes.com/today/2014/06/evergreen-point-transit-station-opens-monday/ |archive-date=September 2, 2017 |url-status=dead}}

The bridge was engineered to accommodate a Link light rail extension with two options (both requiring 30 additional pontoons): one option would be {{convert|116|ft|m}} wide with two lanes each direction, plus light rail to replace the HOV lanes; the other {{convert|150|ft|m|adj=mid|-wide}} option would retain the HOV lanes, two general purpose lanes in each direction, and add light rail.{{cite web |title=SR 520 – Light Rail in the Corridor |url=http://www.wsdot.wa.gov/Projects/SR520Bridge/About/LightRail.htm |publisher=Washington State Department of Transportation |access-date=April 17, 2016 |archive-url=https://web.archive.org/web/20160419023754/http://www.wsdot.wa.gov/Projects/SR520Bridge/About/LightRail.htm |archive-date=April 19, 2016 |url-status=live }} A proposal to include a light rail line with the construction of the bridge was dropped in 2008 after Sound Transit chose to prioritize the East Link Extension on the I-90 floating bridge. A first line on the SR 520 corridor would also cause capacity issues on the section south of the Lake Washington Ship Canal.{{cite news |last1=Carlton Harrell |first1=Debera |last2=Lange |first2=Larry |date=March 17, 2008 |title=Light rail cut from the plan for 520 Bridge |url=https://www.seattlepi.com/local/transportation/article/light-rail-cut-from-the-plan-for-520-bridge-1267504.php |work=Seattle Post-Intelligencer |accessdate=October 29, 2024}}

Electronic tolling with the "Good to Go" system began on the old bridge in 2011; tolling on the new bridge was in place from its opening in 2016. The tolls are projected to generate $1.2 billion by 2056 to pay off bonds for the project as well as bridge operations and maintenance, debt service, future repairs, insurance, and deferred sales tax. The toll varies by time of day as well as day of week and applies in each direction. Rates are reviewed annually to cover all operational costs and debt service. Since August 2024, the rate for standard two axle passenger vehicles ranges from a minimum of $1.35 from 11 p.m. to 5 a.m. to a maximum of $4.90 during peak commuting hours on weekdays; an additional $2 is charged for mail users.{{cite news |last=Lindblom |first=Mike |date=July 10, 2024 |title=520 bridge tolls about to increase |url=https://www.seattletimes.com/seattle-news/transportation/520-bridge-tolls-about-to-increase/ |work=The Seattle Times |accessdate=October 29, 2024}}{{cite web |title=SR 520 Bridge tolling |url=https://wsdot.wa.gov/travel/roads-bridges/toll-roads-bridges-tunnels/sr-520-bridge-tolling |publisher=Washington State Department of Transportation |accessdate=October 29, 2024}} Major holidays are assessed at the weekend rate, which ranges from $1.35 overnight to $2.95 from 8 a.m. to 9 p.m. Vehicles with more than two axels are charged an additional rate.

In 2023, a total of 20.48 million toll transactions were recorded, of which the average rate paid was $3.37; approximately 85 percent of toll transactions were paid through the Good to Go system. A peak of 26.5 million transactions were reported in 2019 with an average revenue of $3.48.{{cite report |author=Stantec |author-link=Stantec |date=June 26, 2024 |title=SR 520 Bridge Traffic and Revenue Study 2024 Report |page=iv |url=https://wsdot.wa.gov/sites/default/files/2024-10/Toll-SR520Bridge-TrafficRevenue-Study2024_1.pdf |publisher=Washington State Department of Transportation |accessdate=October 29, 2024}}

In April 2017, the bridge project was awarded the 2017 Grand Conceptor Award from the American Council of Engineering Companies (ACEC).{{cite press release |date=April 26, 2017 |title=New SR 520 floating bridge named America's top engineering feat |url=http://www.wsdot.wa.gov/news/2017/04/26/new-sr-520-floating-bridge-named-america%E2%80%99s-top-engineering-feat |publisher=Washington State Department of Transportation |access-date=April 28, 2017 |archive-url=https://web.archive.org/web/20170503014644/http://www.wsdot.wa.gov/news/2017/04/26/new-sr-520-floating-bridge-named-america%E2%80%99s-top-engineering-feat |archive-date=May 3, 2017 |url-status=live }}

• Homer M. Hadley Memorial Bridge and Lacey V. Murrow Memorial Bridge, another pair of floating bridges over Lake Washington which connect Seattle to the Eastside via Interstate 90

{{reflist}}

• [http://www.wsdot.wa.gov/Projects/SR520Bridge/ SR 520 Bridge Replacement and HOV Program] {{Webarchive|url=https://web.archive.org/web/20150721151336/http://www.wsdot.wa.gov/Projects/SR520Bridge |date=July 21, 2015 }}
• [http://www.wsdot.wa.gov/Projects/SR520Bridge/Library/Technical.htm SR 520 Project Library] {{Webarchive|url=https://web.archive.org/web/20190526061346/http://www.wsdot.wa.gov/Projects/SR520Bridge/Library/Technical.htm |date=May 26, 2019 }}
• [http://www.wsdot.wa.gov/NR/rdonlyres/E1CE70E3-68E9-4C3B-90BA-00A12AF5955F/0/2017_0400_FBL_Booklet.pdf Project Booklet]

{{Bridges of Seattle}}

Category:2016 establishments in Washington (state)

Category:Bridges completed in 2016

Category:Bridges in Seattle

Category:Road bridges in Washington (state)

Category:Seattle metropolitan area

Category:Toll bridges in Washington (state)

Category:Bridges in King County, Washington

Category:Concrete bridges in Washington (state)

Category:Pontoon bridges in the United States