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SR 520 - Floating Bridge and Landings Project: What's Happening Now?

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Aerial view of the SR 520 floating bridge construction site See more photos from Lake Washington, Tacoma, and Kenmore on our Flickr site.

Updated: June 10, 2014

Construction activities for the new SR 520 floating bridge and landings are underway.

We are currently assembling the new floating bridge on Lake Washington and continue to build bridge components at locations in Aberdeen, Tacoma and Kenmore. 

Current work

Lane and Ramp Closures

Visit the SR 520 Orange Page for specific dates and times.

Lake Washington

West Connection Bridge construction is underway on Lake Washington near Madison Park. During the weekend of June 6 through 9, crews removed a section of barrier west of the existing floating bridge and installed a new, temporary barrier. Crews will work on the two-foot section of roadway deck behind the barrier to chip concrete from the rebar in preparation for connecting the new bridge to the old highway. Check out the progress graphic for more information on current construction activities. This bridge is planned for completion by fall 2014.

In May, crews began joining the larger pontoons. Pontoons V and W were joined in mid-May. In early June, pontoons U and V will be joined. Soon, drivers will notice the new floating bridge beginning to take shape!

Construction of the segmental bridge, or balanced cantilever, near Lake Washington's Medina shoreline is nearly complete for the south (eastbound) section of roadway. In late June, crews will install a nearly 200- foot-long, steel transition span, connecting the fixed portion of the bridge to the floating bridge.

Pontoons are currently being stored in the lake's west side staging area. Crews have also begun adding rock ballast to some of the pontoons to prepare them for joining.

Construction activities and project barges completely block the east navigation channel. These obstructions alter use of the east navigational channel and SR 520 drawspan. Read more information for boaters and SR 520 drivers.


See the latest activity on our Medina construction camera. Curious what you're looking at? Check out this guide.

Segmental bridge construction is nearly complete for the new eastbound lanes. In late June, crews plan to connect this fixed section of bridge to the floating bridge with a nearly 200-foot-long steel transition span.

The new bridge maintenance facility is also beginning to take shape under the new east approach. Crews are constructing walls and have begun to prepare for utility installation. 

Joining of longitudinal pontoons for the new floating bridge began in May 2014 when pontoons V and W were joined. In early June, pontoons U and V will be joined and pontoons T and U will be joined in mid- to late June.


See the latest activity on our Kenmore construction camera. Curious what you're looking at? Check out this guide.

The casting facility where the new roadway deck sections are being constructed is complete. Casting of the concrete deck sections began in March 2014.

Crews will continue to construct the roadway deck sections throughout 2014. A total of 766 sections are needed to complete the roadway for the new floating bridge.

In early June crews will deliver and assemble girders for a nearly 200-foot-long transition span. The girders will be assembled on a barge at the wharf and then floated down to the Medina construction site for installation.

For more information about the work planned in Kenmore, view our project page.


See the latest activity on our Tacoma construction camera. Curious what you're looking at? Check out this guide.

Crews recently completed construction of the fifth of six cycles of supplemental stability pontoons being constructed in Tacoma. These eight pontoons are currently being floated out of the casting basin in Tacoma and will be temporarily moored at the Port of Tacoma until they are needed for bridge assembly.

In early June, crews will begin constructing the final cycle of supplemental stability pontoons in Tacoma. KGM plans to complete construction of this cycle this fall. 

Check out photos on our Tacoma Flickr page.


Crews have begun constructing the fifth cycle of six pontoons at the casting facility in Aberdeen. This cycle of pontoons is planned for completion in the fall. 

You can find more information on the Pontoon Construction Project on the project website.

Watch our YouTube video to learn more about the float-out process.