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

Updated: April 2016

Construction of the new SR 520 floating bridge is nearly complete and crews are working to switch eastbound traffic onto the new bridge. After all traffic has moved to the new bridge, crews will begin decommissioning the old bridge.

Current work

Past work


Noise from new bridge

We have heard from a number of Medina residents and the city of Medina regarding noise that can be heard from the new floating bridge since it was opened to westbound traffic on Monday, April 11. Based on these comments, our team contacted our noise experts to investigate this issue.

Preliminary results of our investigation and an explaination of how noise is measured can be found in our April 29 SR 520 Medina Noise Concerns Update (pdf 1.9 mb). Please note, noise level measurements were initially taken while traffic was travelling eastbound on the old bridge and westbound on the new bridge. We are currently taking additional noise measurements now that all traffic is on the new floating bridge. Please stay tuned for more updates.

If you have questions or comments concerning this noise question, please contact us at and include on your email.

Lane and Ramp Closures

Westbound traffic switched to the new SR 520 floating bridge over the weekend of April 8-11. Eastbound traffic will switch to the new bridge after the full weekend closure during the weekend of April 22-25.

Pedestrians and bicyclists will be able to access the new extension of the SR 520 trail onto the floating bridge after the final traffic switch planned for the weekend of April 22-25. An exact date will be determined soon.

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

Traffic will shift over two separate weekends 
Click the image above for a larger, printable graphic (pdf 5 mb) showing how traffic will flow during the switch from the old floating bridge to the new floating bridge. 

Lake Washington

Beginning as early as Monday, April 25, and continuing through the end of 2016 Kiewit/General/Manson, a Joint Venture (KGM) will complete decommissioning work to remove the old SR 520 floating bridge from Lake Washington. The pontoons have been sold and will be removed from Lake Washington through the Hiram M. Chittenden Locks in Ballard. The majority of the remaining components will be dismantled onsite and hauled to concrete recycling facilities, where most of the materials will be processed for reuse as dry aggregate for other paving projects.

SR 520 decommission timeline
Click the image above for a
larger, printable graphic (pdf 1 mb) showing a timeline of bridge decommissioning activities.

During decommissioning of the old bridge, neighbors can expect to see barges, cranes, excavation equipment, loaders, trucks and protective screening for neighbors near the shoreline. The noisiest work activities will take place during the first three months of decommissioning activities near the east and west approaches. Work activities include removal of the bridge deck, approaches, and components from the tops of the pontoons. Nearby residents can expect to hear a loud, consistent noise similar to an industrial fan and the cutting and dismantling of materials.

In the first few weeks of April we heard from several project neighbors about bright lights coming from the new bridge. WSDOT engineers are working to verify the source (or sources) to identify the best solution. As part of a short-term solution, WSDOT has turned off some lighting until a long-term solution is identified.


Decommissioning activities on the east approach of the existing bridge will begin as early as Monday, April 25, and continue through the end of 2016. After the east approach has been removed, KGM will begin shoreline restoration activities and installing the new viewpoint trail and noise walls south of the new bridge. For more information, visit the Lake Washington section of this webpage.

Click here for a notification sent on April XX to Medina neighbors regarding decommissioning activities.


Decommissioning activities on the west approach of the existing bridge will begin as early as May and continue through the end of 2016. For more information, visit the Lake Washington section of this webpage.


Casting of the concrete deck sections began in March 2014 and was completed in August 2015. A total of 776 sections were built. These sections form the roadway for the new floating bridge. For more information about the work done in Kenmore, visit our project page .


Construction of the 44 supplemental stability pontoons built in Tacoma was completed in December 2014. At this time, no other SR 520 construction activities are planned in Tacoma. Check out photos of construction in Tacoma on our Flickr page


On March 10, 2015, crews floated the sixth and final cycle of pontoons from the casting facility in Aberdeen. The last three pontoons arrived on Lake Washington on April 9, 2015.

You can find more information on the Pontoon Construction Project section of the program website and watch videos of the float-out process on our YouTube page.