Skip Top Navigation

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


Stay Connected

Updated: Feb. 3, 2017

The new SR 520 floating bridge is open to traffic in both directions and decommissioning activities to remove the old bridge from Lake Washington are underway.

Current work

Past work


Upcoming nighttime work

Through spring 2017, crews will work at night to complete several activities including: grading of the final construction area; paving; and screening wall construction along the south side of the Evergreen Point Road lid.

Work details:

  • Continuing through spring 2017, crews will work Monday through Saturday, 7 p.m. to 7 a.m.
  • Crews will use excavators, graders and paving machines to complete final construction-area paving.
  • The graphic below highlights the remaining work in Medina, including estimated timeframes for each activity.

Residents can expect to see and hear the following:

  • Large construction equipment such as excavators, lights and noise from machinery and other equipment.
  • Crews will minimize construction noise by using ambient back-up alarms and limiting machine idling when possible.

  Work planned for Medina through early 2017
Click the image above for a graphic (pdf 103 kb) showing the remaining work in Medina, including estimated timeframes for each activity.

Lane and ramp closures

Decommissioning activities to remove the old floating bridge from Lake Washington are underway and will continue through February 2017. During this time, drivers and transit riders can expect intermittent lane closures. Visit the SR 520 Orange Page for closure information.

Decommissioning information and materials

Decommissioning activities by Kiewit/General/Manson, A Joint Venture (KGM) to remove the old SR 520 floating bridge from Lake Washington are nearly complete. All decommissioning activities are scheduled to be complete by March, with minor marine operations continuing through spring 2017. 

Some old bridge materials were dismantled on barges on Lake Washington, while others were removed from Lake Washington before processing. The majority of the materials were dismantled onsite and hauled to concrete recycling facilities, where most of the materials were processed for reuse as dry aggregate for other paving projects.

The 31 old bridge pontoons were removed from Lake Washington through the Hiram M. Chittenden Locks in Ballard. They have been sold to TrueNorth Operations Group . In the past, TrueNorth has converted used pontoons into docks, artificial reefs, and wharfs. The final pontoon left Lake Washington on Jan. 14, 2017. 

During these decommissioning activities, neighbors can expect to see: barges, cranes, excavation equipment, loaders, trucks and protective screening above work barges. Nearby residents can also expect to hear a loud, consistent noise similar to an industrial fan, and the cutting and dismantling of materials. KGM will utilize best management practices throughout the decommissioning process.

Due to the dynamic nature of construction, this schedule is subject to change. If you have questions about this work, please contact the KGM construction hotline at 425-576-7098 .

See the Lake Washington , Medina , and Seattle sections below for more information about specific work occurring in these areas.

Decommissioning plans for the old SR 520 floating bridge
Click the image above for a decommissioning folio (pdf 392kb) showing a timeline of bridge decommissioning activities.

Lake Washington

All Lake Washington decommissioning work activities will occur within the project limits of construction (within approximately 1,000 feet of the new bridge). Activities include:

  • Removing the old bridge roadway deck (complete).
  • Removing the east and west transition spans (complete) and pier columns (through February 2017).
  • De-tensioning and separating old pontoons (complete).
  • Removing old anchor cables (complete).
  • Moving decommissioned pontoons from the east side staging area to the west side staging area near Seattle prior to final removal from Lake Washington via the Hiram M. Chittenden Locks in Ballard (complete).
  • Removal of west side and east side staging areas (complete).
  • Utilizing approved truck haul routes through Medina, Clyde Hill, and Bellevue (pdf 326 kb).


In addition to decommissioning activities, crews are working to:

  • Conduct air monitoring in Medina to gauge what level of particulate matter may drift from bridge-removal activities on Lake Washington. This fact sheet provides more information on the monitoring effort (pdf 152 kb).
  • Complete noise walls south of the new bridge.
  • Construct a new viewpoint trail south of the new bridge.
  • Complete landscape installation and shoreline restoration activities.
  • Air quality testing was conducted in Medina by the Washington State Department of Ecology from Aug. 25 through Sept. 27, 2016, while decommissioning of the old floating bridge was in progress. The Department of Ecology’s report (pdf 509 kb) states that particulate matter levels were well within the limits of the National Ambient Air Quality Standard.


Current Seattle decommissioning work activities include:

  • Removal of the final, underwater pier footing near the west navigation channel.

You can learn more about our bridge-removal work through these resources:

On July 14, 2016 , the Governor's office facilitated a bridge decommissioning meeting with WSDOT, Department of Ecology, elected officials and interested stakeholders:

On June 9, 2016, WSDOT and KGM presented to the Lake Washington Mayors monthly meeting:


Light from new bridge

After the new SR 520 floating bridge opened in early April 2016, we heard from several project neighbors regarding lights that can be seen on the north side of the new bridge. Based on initial comments, we turned all nonessential lighting off until we could conduct tests on the new lighting along the Regional Shared-Use Path (RSUP). The lighting was reactivated in July 2016 and is active from dusk to dawn.

Measurements of the lighting from the path were conducted in May and July 2016. While the lighting was found to be within the limits listed in permits and environmental documentation, WSDOT is committed to working with the community to evaluate potential modifications to the RSUP lights. The links below provide information on the progress of these evaluations.

The 50-watt bulbs have been failing at a high rate and much faster than expected. The bulb failure is likely due to an incompatibility between the lower wattage bulbs and the fixture wiring that is designed for 100-watt bulbs. We are working to address this issue in order to maintain the safety of those on the path and protect the fixtures from condensation. If there are no bulbs in the fixtures, then condensation may build up, causing rust and damaging the fixture.

We are currently testing louvered shields on lights along the shared-use path. We are in the process of testing prototype shields on both 100-watt and 50-watt bulbs, both of which are currently installed along the path.

Lighting updates

Meetings and materials
On Tuesday, Nov. 29, WSDOT and representatives from the 46th Legislative District hosted a community meeting to discuss WSDOT’s evaluation of the lights on the SR 520 Regional Shared-Use Path (RSUP). See the materials presented at the briefing:

On Thursday, Nov. 17 , WSDOT staff met with elected officials to review the latest results from evaluations of the lights along the Regional Shared-Use Path (RSUP). See the materials presented at the briefing . (pdf 2.2 mb)

If you have questions or comments concerning lighting on the new bridge, please contact us at .  

Noise from new bridge

Shortly after the new SR 520 floating bridge opened to westbound traffic in April, WSDOT began receiving concerns from Medina residents regarding sounds coming from the new bridge. At that time we began conducting an investigation that includes collecting sound measurements on both the old and new floating bridges.

We have also heard from some Seattle residents on this topic. As you know, the west end of the new bridge is still in an interim configuration as WSDOT and our contractors work to complete the west approach bridges between Montlake Boulevard and the new floating bridge.

Meetings and materials

We are keeping track of those who notify us about sounds from the new bridge and will include everyone in future updates. If you have questions or comments concerning this noise question, please contact us at and include on your email.

Bicycle and Pedestrian Path

The new regional shared-use path (RSUP) opened as an out-and-back path from Medina on Friday, July 22. The trail is a continuation of the trail constructed by the Eastside Transit and HOV project, which extends from 108th Ave NE in Bellevue, runs along the north side of SR 520 to the lid at Evergreen Point Road. The path now extends 1.3 miles onto the new floating bridge. When WABN is open to traffic in summer 2017, the path will connect to regional trails in Seattle.


Through December 2016, KGM will continue to use the Kenmore site for hauling of materials. This work will only happen during daytime hours.

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 completed 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.