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SR 520 - I-5 to Medina: Bridge Replacement and HOV Project

View a simulated rendering of the I-5 to Medina project:
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Waves batter the existing SR 520 bridge during a winter storm.


April 2015


The I-5 to Medina: Bridge Replacement and HOV Project will replace the interchanges and roadway between I-5 in Seattle and the eastern end of the floating bridge.

Why is WSDOT pursuing this project?

Approximately 70,000 vehicles cross Lake Washington every day on the SR 520 floating bridge. It’s a key regional route for commuters and freight.

After floating for more than 50 years, the four-lane bridge is often clogged by traffic and is showing its age.

The floating bridge pontoons are vulnerable to windstorms, and bridge support columns are vulnerable to earthquakes.

The End Result

The I-5 to Medina Bridge Replacement and HOV Project includes a new floating bridge and highway with six lanes, including two general-purpose lanes and one new transit/HOV lane in each direction.

The project also takes key steps to get ready for future light rail, help manage traffic in the Arboretum and transform the future corridor from Montlake to I-5 into a city parkway with landscaped lids and medians.

Project Benefits

The new SR 520 corridor through Seattle will:

  • Provide transit connections and priority.
  • Create a pedestrian-friendly urban interchange at Montlake Boulevard.
  • Restore park area and connections next to the Washington Park Arboretum.
  • Reduce noise levels from the Portage Bay Bridge.
  • Be ready for light rail if the region chooses to fund it in the future.

What is the project timeline?

  • Spring 2011: Published final environmental impact statement
  • Summer 2011: Received Record of Decision
  • Summer 2011: Selected contractor team for new SR 520 floating bridge
  • 2012: Began construction of floating bridge
  • 2014: Began construction of the West Approach Bridge North
  • 2016: Open new floating bridge to traffic
  • 2017: Open new West Approach Bridge North

The schedule for constructing segments of the corridor from I-5 to Lake Washington is pending additional funding.

Financial Information

We are moving forward with construction on a new SR 520 floating bridge, which is fully funded by a variety of state and federal sources, including SR 520 tolling, which began in December 2011.

We are continuing to work with the Legislature to fund elements of the project from I-5 to the floating bridge.

Visit the SR 520 Costs, Funding and Tolling page for additional information.

How can I get more information?

Phone: 206-770-3500

Infoline: 1-888-520-NEWS (6397)

24-hour construction hotline: 206-708-4657

Twitter: @WSDOT_520

Mail: I-5 to Medina: Bridge Replacement and HOV Project
SR 520 Bridge Replacement and HOV Program
999 3rd Avenue, Suite 2200
Seattle, WA 98104

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