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 .” To get the most up-to-date information on current SR 520 construction activities or planned travel restrictions, visit our Construction Corner.

Project news

  • Thank you to all who attended the June 6 design and preconstruction open house for the SR 520 Montlake Project. If you missed the meeting or you’d like to revisit the information, we invite you to check out the online open house, which will be open until Thursday, June 20. Thanks to all who participate!
  • We held a public meeting on May 23 to update the community on the SR 520 Montlake Project and how it will affect the Montlake Market and 76 gas station. We informed meeting attendees that WSDOT will take ownership of the property in June, and that WSDOT leadership determined the market cannot practicably be preserved during SR 520 construction -- and must be removed. We also discussed a new legislative directive (pdf 1.1 mb), pages 59-60, to WSDOT that seeks to establish a temporary market or food service in Montlake during Montlake Project construction. These market-related materials provide more information:

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

Relocation of wireless-communications structure

A company named Crown Castle currently operates a wireless-communications facility – 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. Please read our Q&A document (pdf 185 kb) for additional information.

More Montlake Project information

  • The city of Seattle granted WSDOT a noise variance 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. 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
  • Summer 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 in late summer / early fall 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.