Skip to main content

Final touches for Seattle’s SR520 floating bridge

Construction crews in the US state of Washington are finishing bicycle trails and pedestrian paths leading up to the award-winning SR 520 floating bridge. The Evergreen Point Floating Bridge - officially now the Governor Albert D. Rosellini Bridge - carries Washington State Route 520 across Lake Washington in Seattle. The 2.35km-long floating span is the longest floating bridge in the world and at 35m the world's widest. It opened in April last year as a replacement for the original 50-year-old four-lane
November 21, 2017 Read time: 2 mins
Construction crews in the US state of Washington are finishing bicycle trails and pedestrian paths leading up to the award-winning SR 520 floating bridge.

The Evergreen Point Floating Bridge - officially now the Governor Albert D. Rosellini Bridge - carries Washington State Route 520 across Lake Washington in Seattle. The 2.35km-long floating span is the longest floating bridge in the world and at 35m the world's widest.

It opened in April last year as a replacement for the original 50-year-old four-lane Evergreen Point Floating Bridge which was 40m shorter. The new US$751 million bridge has six lanes of traffic as well as a 4.26m-wide separate pedestrian and cycling path. Recent work includes trail railing and lighting, drainage systems and trail connections on land to enhance the safety and modality of the structure and connect it to a system of paths and trails in the surrounding area.

World Highways, in a key project report in 2014, reviewed construction of the toll bridge that floats on 77 concrete pontoons, compared to 33 for the original bridge. The longest pontoons are 109m and are 22.86m wide and 8.53m high. Among them are 21 of the heaviest, widest and deepest longitudinal pontoons ever built, each weighing nearly 10,000tonnes.

There are 54 supplemental pontoons allowing the structure to withstand winds of up to nearly 160kph and nearly 2m-high waves – estimated to occur in the Puget Sound area every 100 years.

The American Council of Engineering Companies (ACEC) recently bestowed the 2017 Grand Conceptor Award upon the bridge for being “the nation’s best overall engineering achievement”. The ACEC considered 162 projects from all over the world for the award. General engineering consultant on SR 520 project was HDR while Kiewit/General/Manson was the bridge’s design-builder. Lead design consultant was KPFF.

Related Content

  • England’s new Sunderland Bridge renamed Northern Spire
    December 12, 2017
    The new Sunderland Bridge - on track to open in the spring - was officially named Northern Spire during a recent event on the bridge. The official naming followed a week-long public vote in which 10,000 people chose their favourite name from an official list of three names. Northern Spire received almost half of the votes, according to bridge officials. The other names were Lumen Point (34% of votes) and The Prism which received 17%. The two-span cable-stayed bridge across the River Wear in northeast
  • Consorcio Panama Cuarto Puente wins fourth Panama bridge contract
    August 1, 2018
    Panama has decided to award a contract for the design and construction of a fourth bridge over the Panama Canal to Consorcio Panama Cuarto Puente. China Communications Construction Company and its subsidiary China Harbour Engineering Company are heading up the consortium for the US$1.42 billion project. Other consortia that put in bids included Dragados Sucursal Panamá and Astaldi-Daelim. News agencies report that the government initially chose the Chinese consortium in June but the final award was
  • Italian JV wins Denmark’s Storstrom Bridge construction deal
    October 27, 2017
    An Italian joint venture has won the construction contract for Denmark’s replacement 4km-long road and rail Storstrom Bridge. The Danish Road Directorate – Vejdirektoratet - awarded the work to contractors Itinera, Condotte and Grandi Lavori Fincosit along with bridge design consultant Seteco Ingegneria as a subcontractor. Estimated cost is around €280 million for the 26m-wide single-support cable-stay structure. The European Union will subsidise the work to around €15 million.
  • Parsons’ Ohio River Bridges East End Crossing Project opens
    January 3, 2017
    In the US, the Ohio River Bridges East End Crossing—now named Lewis and Clark Bridge—opened to traffic in mid-December.