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 Corner and its interactive construction map. You also can view Montlake Project construction photos and time-lapse action, taken 'round the clock at 10-minute intervals, by four mounted construction cameras. In addition, this question-and-answer document (pdf 544 kb) addresses an array of project-related issues.

Project news

  • The Montlake Project spring online open house is now live! See the latest project designs, take a survey about your priorities, and preview what crews will work on when construction safely resumes.
  • Register now for the next online monthly meeting, Wednesday, June 3, at noon. There will be a presentation followed by a Q&A. Missed this month's construction meeting? You can view a video recording and the presentation slides (pdf 2.16 mb).
  • In keeping with Gov. Inslee’s phased approach for reopening Washington’s economy, crews resumed some low-risk construction activities the week of Monday, May 18, including removing the former Montlake Market and 76 gas station buildings. As we restart construction, all crews must follow specific safety protocols (pdf 138) for preventing exposure to the coronavirus.
  • The Montlake Project Information Center is currently closed until further notice due to the COVID-19 outbreak.
  • Earlier this year, crews built two massive gantry cranes in Montlake to help remove and replace the old eastbound bridge. You can now watch a time-lapse video of the assembly process!
  • We opened a new biking and walking trail in Montlake to cross SR 520 during the highway's reconstruction. Read more about it in our March 12 email update. 
  • A company named Crown Castle has temporarily relocated its wireless-communications facility from the former Montlake Market property to the WSDOT Peninsula construction staging area, near Lake Washington Boulevard East and East Miller Street. The "monofir" facility now on the WSDOT Peninsula ensures continued emergency 911 service and uninterrupted cell phone service for the surrounding area. Please read our Q&A document (pdf 152 kb) for additional information.  

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

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 detours to keep traffic flowing in Montlake during construction, 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 will be removed. However, under a directive from the state Legislature, WSDOT is exploring opportunities for a smaller, temporary market or food service to operate in Montlake during the approximate four years of Montlake Project construction. Once Montlake Project construction is complete, WSDOT will sell the remaining, unimproved portion of the market property – a sale that will happen about six years sooner than we’d previously planned. You'll find more information by reading our answers to market-related questions (pdf 105 kb) we received during our 2019 online survey and from our November 2018 public meeting (pdf 250 kb).

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 1.2 mb) and the city's decision granting the variance. (pdf 4 mb) 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.

map of future SR 520 elements upon completion of the Montlake Project

Plan view of key Montlake Project elements. View a larger image (png 5.6 mb)

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.