SR 520 - Montlake Project

Project overview

The construction now underway for the SR 520 Bridge Replacement and HOV Program is the Montlake Project. This project is the first stage of all remaining SR 520 improvements in Seattle – what we call the “Rest of the West.” For the most up-to-date information about current SR 520 construction activities and planned road closures, check our SR 520 construction map. You also can view construction photos taken 'round the clock at 10-minute intervals by four construction cameras. For questions about construction, please visit our Contact Us page

Project news

  • Crews will close SR 520 this weekend to remove the old Montlake Boulevard overpass. From 9 p.m. Friday, Oct. 22, to 5 a.m. Monday, Oct. 25, SR 520 and the SR 520 Trail across Lake Washington will be closed between I-5 in Seattle and the Eastside. Read more about it on our Construction Corner webpage and in our latest news release. Please note, the eastbound off-ramp to Montlake Boulevard is scheduled to close at 8 p.m. Friday night.
  • Our next monthly online meeting is Wednesday, Nov. 10, at 12:30 p.m. Join us to learn more about what's ahead for Montlake Project construction. Registration is now open online. Did you miss our October meeting? We've posted the meeting presentation (PDF 8.8MB) so you can see what we covered.

Needs and benefits

SR 520’s 1960s-era west approach bridge, supported by hollow columns, is at risk of failure in a severe earthquake. In addition, the highway’s old, four-lane segment in Seattle is typically at capacity during peak periods. Now that we’ve completed reconstruction of the highway’s Eastside segment and replaced the old floating bridge, we are moving forward to complete the remaining SR 520 safety and mobility improvements from Lake Washington to I-5.

The end result

  • A new, seismically stronger West Approach Bridge South, parallel to the completed West Approach Bridge North, to carry three lanes of eastbound traffic past Montlake Boulevard East to the new floating bridge
  • A community-connecting highway lid and transit hub at Montlake Boulevard East
  • A rebuilt SR 520 / Montlake Boulevard East interchange
  • A bicycle-pedestrian “land bridge” over SR 520, east of the Montlake lid, connecting the Arboretum and points northward, including the University District

Project benefits

  • A safer highway for motorists and transit riders by replacing the old, structurally vulnerable west approach bridge
  • Improved regional mobility from the addition of transit/HOV lanes across Lake Washington, direct-access ramps for buses and carpools to and from a regional transit hub on the Montlake lid, and added lane capacity at the Montlake Boulevard East interchange
  • More nonmotorized-travel options from a new north-south bicycle and pedestrian land bridge over SR 520, connecting Arboretum trails with local and regional bicycle/pedestrian routes in Montlake and the University District
  • New community open space and trail connections from construction of a landscaped Montlake lid
  • Fewer traffic backups thanks to wider highway shoulders that allow disabled vehicles to pull over without blocking traffic
  • A cleaner, healthier environment from the creation of treatment systems for SR 520 stormwater runoff
  • More open and natural park area in the Arboretum with the removal of old SR 520 on- and off-ramps and the never-completed R.H. Thomson Expressway "Ramps to Nowhere"

Montlake Market update

WSDOT acquired the Montlake Market and 76 gas station property in June 2019 to enable permanent improvements to the SR 520 corridor, provide space for rerouted traffic during Montlake Boulevard's reconstruction, and efficiently stage the work. A WSDOT analysis showed that keeping the market open during Montlake Project construction was impracticable, so the market and gas station closed at the end of 2019 and the buildings were removed. However, under a directive from the state Legislature, WSDOT solicited vendor proposals to operate a smaller, temporary market or food service during the approximate four years of Montlake Project construction. The selected vendor opened a Burb’s Burgers food truck in October 2020 on a portion of the former market property. Once Montlake Project construction is complete, WSDOT will sell the remaining, unimproved portion of the market property. You'll find more information by reading our answers to market-related questions (PDF 105KB) we received in a 2019 public survey and a November 2018 public meeting (PDF 250KB).

Project noise variance

Construction of the SR 520 Montlake Project has moved into high gear with contractor crews now working to build a Montlake lid over the highway, an improved Montlake Boulevard interchange, and other corridor enhancements. Some of the work needs to occur at night to avoid disruptions to weekday traffic, so we applied for and received a noise variance from the city of Seattle. Learn about the conditions for our nighttime work by reading our noise-variance application (PDF 1.2MB) and the city's decision granting the variance. (PDF 4MB) You'll find even more information about nighttime work and our efforts to limit construction noise on our SR 520 Construction Corner.

Project design

Our website’s planning-documents webpage contains extensive information about the Seattle Community Design Process and other project-design initiatives and reports. There will be more design work for future Rest of the West projects, with additional opportunities for public comment.

A rendering of a highway through a residential neighborhood with green space covering the highway labeled Montlake lid. There are other trail and park elements nearby labeled.

Plan view of key Montlake Project elements. View a larger image (PDF 476KB)

A rendering of a lid over a freeway with on and off ramps shown. There is a large green space in the middle. the lid is in the middle of a neighborhood

Conceptual illustration of a new Montlake lid over SR 520, looking west, with 24th Avenue East in the foreground and Montlake Boulevard in the distance.

Rendering of a pedestrian plaza with bus stops and lots of people standing, walking and sitting around.

Conceptual illustration of the transit hub on a new Montlake lid over SR 520.

A rendering of a viewpoint with three people reading an informational board and looking over a lake with an island in it.

Conceptual illustration of an overlook on a new pedestrian land bridge over SR 520 in the Montlake area, looking east across Marsh Island and Union Bay.


  • Fall 2018: Select contractor
  • Summer 2019: Begin construction
  • 2023-2024: Complete project construction


This project, with a $455 million contract cost, is part of the remaining $1.6 billion in SR 520 improvements from Lake Washington to I-5 – the “Rest of the West.” These improvements are funded by the 2015 Connecting Washington transportation legislation. For more information on SR 520 funding, visit the Budget and Performance page.

A commitment to fair contracting

WSDOT is committed to meeting the governor's voluntary goal of providing 26 percent of the contract value for Connecting Washington transportation projects – including the SR 520 Montlake Project – to minority-owned, women-owned, veteran-owned and disadvantaged small businesses. Learn more about the SR 520 Diversity and Inclusion Program.


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.