SR 520 - I-5 to Lake Washington - Rest of the West

Project news

  • We're holding a public meeting on Wednesday, Jan. 30, to share more information and gather community feedback on potential scenarios and tradeoffs associated with our efforts to preserve the Montlake Market building after WSDOT acquires the market property. During this meeting, we'll also discuss ideas we're evaluating for preserving the market building and review our Montlake Project contractor's current construction plan. The meeting is scheduled for 5:30 to 7:30 p.m. at St. Demetrios Greek Orthodox Church, 2100 Boyer Ave. E., in Seattle.
  • If you missed our November 2018 meeting on the Montlake Market, you can read our answers to questions (pdf 250kb) that community members posed on this topic. You also can watch a video replay of the entire proceeding on YouTube or view the meeting’s presentation slides on Flickr.
  • We selected Graham Contracting Ltd. last October as the design-build contractor for the upcoming Montlake Project. Read more about the announcement in our recent news release.
  • In September 2018, we announced an updated construction schedule for the remaining SR 520 reconstruction projects. More information on the construction timeline can be found below.
  • The first phase of this construction, known as the Montlake Project, is scheduled to begin in early 2019.
  • In 2020 we'll begin construction on a new transit/HOV link between SR 520 and the I-5 Express Lanes. Learn more about this connection in our latest video.


Now that we’ve completed reconstruction of SR 520’s Eastside corridor, built a new floating bridge on Lake Washington and completed the first of two parallel bridges across Union Bay, we are focused on completing the remaining SR 520 improvements from Lake Washington to I-5. These phased improvements, which we call the "Rest of the West," include:

  • the second of two, parallel west approach bridges.
  • landscaped highway lids in Seattle's Montlake and Roanoke neighborhoods.
  • a new bicycle and pedestrian land bridge over SR 520.
  • a new bus/carpool connection between SR 520 and Seattle’s South Lake Union area.
  • a new Portage Bay Bridge.
  • a second bascule bridge over the Montlake Cut.

Why is WSDOT pursuing this project?
SR 520’s 1960s-era bridges are structurally vulnerable and at risk of failure in a severe storm or earthquake. In addition, the highway’s old, four-lane segment is typically at capacity during peak periods. The projects we'll construct, in phases, for the Rest of the West will complete all planned safety and mobility improvements on SR 520 from Lake Washington to I-5.

The end result

  • A new, seismically stronger West Approach Bridge South to carry three lanes of eastbound traffic past Montlake Boulevard to the new floating bridge
  • Community-connecting highway lids in Seattle’s Montlake and Roanoke neighborhoods
  • A new, seismically stronger Portage Bay Bridge
  • A landscaped, 30-foot-wide bicycle and pedestrian crossing over I-5
  • A second bascule bridge across the Montlake Cut
  • A bicycle-pedestrian “land bridge” over SR 520 connecting the Arboretum and points northward, including the University District
  • Mitigation and trail-improvement projects in Seattle parks, natural areas and neighborhoods

Project benefits

  • A safer highway for motorists and transit riders by replacing structurally vulnerable bridges
  • Improved regional mobility by adding dedicated transit/HOV lanes across the entire SR 520 corridor, in both directions, and direct-access ramps to and from a regional transit hub on the Montlake lid
  • Greater transportation options by completing a regional, cross-lake bicycle/pedestrian path along the entire corridor, with connections to local trails on both sides of Lake Washington
  • Safer, more efficient north-south travel through Montlake from a second bascule bridge across the Montlake Cut
  • Quicker, safer travel between the Eastside and Seattle’s South Lake Union neighborhood from a new SR 520 transit/HOV connection via the I-5 express lanes  
  • A healthier environment by creating treatment systems for highway runoff, along with other mitigation project

What is the timeline for the Rest of the West projects?

We are constructing the remaining SR 520 improvements in phases between the new floating bridge and I-5. The phased projects are:

Montlake Project

  • Elements: West Approach Bridge South, Montlake lid and interchange, bicycle/pedestrian land bridge over the highway
  • Timeline: construction planned to begin in early 2019; estimated duration: 4-5 years

SR 520 / I-5 Express Lanes Connection Project

  • Elements: new, reversible transit/HOV connection between SR 520 and Seattle’s South Lake Union neighborhood, running on the I-5 express lanes
  • Timeline: construction estimated to begin in 2020; estimated duration: 3 years

Montlake Cut Bascule Bridge Project

  • Elements: second bascule bridge over the Montlake Cut
  • Timeline: WSDOT will conduct additional coordination with community stakeholders and agency partners regarding the scope of this project

Portage Bay Bridge and Roanoke Lid Project

  • Elements: Portage Bay Bridge, Roanoke lid, I-5 bicycle and pedestrian crossing
  • Timeline: construction estimated to begin in 2023; estimated duration: 6 years

More project information

  • We receive a lot of questions about what's ahead for SR 520 reconstruction in Seattle. Read our FAQs (pdf 123 kb) to learn the latest.
  • The city of Seattle granted us a noise variance last April for the upcoming Montlake Project. More information on the variance (document #3030792) is available on the city of Seattle's website. You also can read our Q&A (pdf 539 kb) on the variance.

Project design

  • Our website’s planning-documents webpage contains extensive information about the Seattle Community Design Process and other project-design initiatives and reports for the Rest of the West projects.

Financial Information

  • The state Legislature's 2015 Connecting Washington transportation legislation authorized $1.64 billion in funding to complete SR 520 improvements from Lake Washington to I-5. For more information on SR 520 funding, visit the Budget and Performance page.


Here are some resources you can use to stay informed about this project:

If your organization is interested in receiving a project briefing or presentation, please contact us.

Thumbnail map of the Montlake area. State Route 520 is highlighted in orange

A thumbnail view of the rest of the west project map for the state route 520 program, showing the western end of 520 outlined for various projects.
Rest of the West timeline
View larger image (pdf 737 kb)