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SR 520 floating bridge construction to begin on Lake Washington

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Date:  Monday, March 26, 2012

Contact: Jeff Switzer, WSDOT SR 520 Communications, 206-770-3547 (Seattle) or 206-819-7230 (cell)
WSDOT’s Flickr site has renderings of the future SR 520 floating bridge.

SEATTLE – Replacement of the world’s longest floating bridge will begin visibly on Lake Washington this week as construction crews move barges and heavy equipment into position north of the aging State Route 520 bridge.

Today, the Washington State Department of Transportation and contractor Kiewit/General/Manson, A Joint Venture (KGM), unveiled the latest construction plans and architectural designs for the new floating bridge. Details also will be available for the public at two open houses this week in Medina and Seattle.

"Starting floating bridge construction on Lake Washington is a huge milestone 15 years in the making," state Transportation Secretary Paula Hammond said. "Crews will build a stronger, more reliable floating bridge – and designs show the integrated architectural features will be distinctive and memorable for generations to come."

The new six-lane bridge will include a dedicated lane in each direction for buses and carpools, and a 14-foot-wide path for walkers and cyclists. Five public viewpoints will be built along the path, and four column-like sentinels will mark where the new bridge transitions between land and water.

This week, drivers will see construction barges assemble to form a work zone on the water. Later this summer, the first batch of 77 huge floating concrete bridge pontoons will be towed into the lake and assembled north of the existing 1963 bridge. The target date for opening the new bridge to traffic is the end of 2014.

"We have an aggressive schedule, and contractor crews have more than two years of challenging work ahead of them at multiple work sites around the region," said Julie Meredith, WSDOT SR 520 Program director. Crews for Kiewit-General are building 33 pontoons in Aberdeen as part of a $378 million project. Under a separate $586.6 million contract, KGM is building 44 additional pontoons in Tacoma, 58 massive concrete anchors and hundreds of concrete road decks in Kenmore, and ultimately the floating bridge.

Including highway construction on the Eastside, an estimated 900 people have worked on SR 520 corridor improvements to date, with more expected as floating bridge construction ramps up on Lake Washington.

On March 23, WSDOT received the 18th and final major permit needed to allow construction of the new floating bridge on Lake Washington, capping 15 years of analysis and design. Legislation signed by Gov. Gregoire March 23 allows construction to begin while an appeal of five of those permits is heard by the state Shorelines Hearings Board.

Open house details

WSDOT is hosting open houses in Medina and Seattle. In addition to construction and floating bridge design news, WSDOT staff will share updated information on designs in the Seattle area and our efforts to minimize effects during construction.

  • Medina: 4:30 to 7:30 p.m. Tuesday, March 27, at Three Points Elementary School, 7800 NE 28th St., Medina.
  • Seattle: 4:30 to 7:30 p.m. Wednesday, March 28, at the Museum of History & Industry, 2700 24th Ave. E., Seattle.

WSDOT has $2.43 billion of $4.65 billion budgeted to build improvements in the 12.8-mile SR 520 corridor between Seattle and Redmond.

Details about the new SR 520 can be found at

Americans with Disabilities Act: The meeting sites are accessible to persons with disabilities. Accommodations for people with disabilities can be arranged with advance notice by calling 206-770-3500.

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