SR 520 - Montlake Project

Project overview

The next phase of construction for the SR 520 Bridge Replacement and HOV Program is the Montlake Project. This project is the first stage of construction for all remaining SR 520 improvements in Seattle – what we call the “Rest of the West.”

Project news

  • Our Montlake Project contractor is holding a preconstruction open house on Thursday, June 6, to provide the public the latest project designs, construction schedule, and contractor plans for limiting construction effects within the community. The meeting is scheduled for 5:30 to 7:30 p.m. at St. Demetrios Greek Orthodox Church, 2100 Boyer Ave. E., Seattle.
  • You can read the complete results of our recent public survey regarding the SR 520 Montlake Project, its possible effects on the Montlake Market, and the practicability of WSDOT preserving the market during upcoming SR 520 construction. The survey report (pdf 3.7mb) summarizes the 1,700-plus responses to our online questionnaire and the more than 880 written comments WSDOT received from community members. 
  • We’ve received a lot of questions from the community over the last few months about our upcoming SR 520 construction work in Seattle. With so many of the recent questions focused on the upcoming Montlake Project or, more specifically, on how our work may affect the Montlake Market, we’ve posted our answers to the most frequently asked questions. Below you’ll find:
  • We recently conducted test drilling in Montlake where the Montlake Market and 76 gas station are located, and found contaminated materials in the soil and groundwater. We plan to acquire this property this year to enable construction of improvements to SR 520 as part of the upcoming Montlake Project. You can read the full soil-testing report (pdf 14mb) on the SR 520 website. We’re working closely with technical experts to learn more about the contamination and determine the next steps. The state Department of Ecology's website has more information about the status of the site, including an Initial Investigation Field Report (pdf 1.74 mb). We’ll keep the public informed as we know more.

Needs & 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

Montlake Project improvements in the Montlake area

map showing SR 520 improvements in Montlake area

View a larger image (pdf 690 kb)

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 Boulevard Market property-acquisition update

WSDOT has been working since 2016 to acquire the property where the Montlake Market and 76 gas station are located. The property is needed to construct various permanent project improvements for the SR 520 reconstruction program. On April 30, 2018, the state Court of Appeals affirmed a Sept. 6, 2017, King County Superior Court ruling that the property is needed for public use and that WSDOT may proceed to acquire the property from the owners. In August the Court of Appeals' ruling was appealed to the Washington Supreme Court. On Oct. 2, 2018, the Supreme Court declined to hear the case, upholding the lower courts' decisions. Meanwhile, we are working with the property's tenants to relocate their businesses, including four wireless-service providers currently operating on the property.

WSDOT is also continuing to address a provision in the state Legislature’s 2018 supplemental transportation budget (Engrossed Substitute Senate Bill 6106) regarding the Montlake Market. The proviso states: 

“The legislature recognizes the department [WSDOT] must acquire the entirety of parcel number 1-23190 for construction of the project. The department shall work with its design-build contractor to ensure to the maximum extent practicable that the building housing any grocery store or market currently located on parcel number 1-23190 will be preserved. The legislature recognizes the city of Seattle has requirements in the project area that the department must address and that those requirements may affect the use of parcel number 1-23190 and may affect the ability of the department to preserve any grocery store or market currently located on the property. The department shall meet and confer regularly with residents in the vicinity of the parcel regarding the status of the project and its effects on any grocery store or market currently located on the property. The legislature strongly encourages the city to utilize maximum flexibility in how the department meets the city’s requirements and to be an equal partner in efforts to preserve any grocery store or market on parcel number 1-23190.” 

In response, we've been reviewing engineering and regulatory requirements for the Montlake Project that have a direct effect on the Montlake Market building. At this time, we have not found a way to build the project and preserve the market building. However, as part of the project's Practical Design process, WSDOT is working with our Montlake Project contractor and the city of Seattle, in consultation with legislators and engagement with the community, to evaluate potential options that may allow preservation of the Montlake Market building. 

Relocation of wireless-communications structure

A company named Crown Castle currently operates a wireless-communications structure – called a “monopole” – on the Montlake Market property. The pole serves two wireless carriers. There are also two facilities on the roof of the market that serve two additional wireless carriers. In order to maintain emergency 911 service and uninterrupted cell phone service for the Montlake area, Crown Castle is working with WSDOT to remove its wireless equipment from the Montlake Market property and erect a new, temporary wireless structure on the nearby WSDOT Peninsula. The new pole will be able to accommodate all four wireless-service providers (AT&T, Sprint, T-Mobile and Verizon) that currently use the Montlake Market property. 

Regardless of whether the Montlake Market building can be preserved, the existing wireless communication facilities located on the property need to be removed due to safety concerns, access restrictions and maintenance needs during SR 520 construction activities. 

Crown Castle is proposing that the new, temporary structure’s design resemble a tree to better blend into the surrounding area. The new pole is expected to be at the WSDOT Peninsula location through the completion of SR 520 construction, at which point, we'll work with Crown Castle to relocate its pole to a permanent location. If you have additional questions, please read our Q&A document (pdf 185 kb).

More Montlake 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.

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.

Montlake Project design rendering

Artistic rendering of a Montlake lid transit hub

Artistic rendering of the transit hub on a planned SR 520 highway lid in Montlake.


  • Fall 2018: Select contractor
  • Spring 2019: Host public preconstruction open house 
  • Spring 2019: Begin construction
  • 2023-2024: Complete project construction

Temporary traffic shift

To enable the removal of the old west approach bridge over Union Bay and the construction of a new west approach bridge for eastbound traffic, we will shift all SR 520 traffic onto the West Approach Bridge North during Montlake Project construction in 2019.

graphic of SR 520 traffic shift during Montlake Project construction

View larger image (pdf 407 kb)


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.