Plans and process
Over the last decade, Seattle’s population and employment boomed, especially in the South Lake Union neighborhood. At the same time, the Eastside’s technology-driven cities continued to see rapid growth. These two factors underscore the importance of a safe, reliable transit/HOV link between Seattle and the Eastside via SR 520. This project addresses this issue by creating a direct bus and carpool connection from SR 520 to South Lake Union and downtown Seattle.
This project is a central part of the larger, ongoing SR 520 Bridge Replacement and HOV Program to reconstruct the SR 520 corridor from I-405 in Bellevue to I-5 in Seattle. We’ve already completed several phases of the program, including:
The Montlake Project, currently under construction, is completing the second of two parallel west approach bridges over Union Bay. This project includes building a new landscaped lid over the highway, and a bicycle and pedestrian bridge to the east of the lid.
When the corridor’s reconstruction is fully completed in the late 2020s:
- All of SR 520’s major bridges will be replaced with stronger structures.
- The bus/carpool lanes and a regional bicycle and pedestrian path will extend from Seattle east to Redmond
- Travelers will have safer on and off-ramps and improved connections to transit, local streets, and local and regional trail networks.
- Safer, more reliable bus and carpool travel between the Eastside, the South Lake Union area, and downtown Seattle through a new, reversible transit/HOV lane that connects SR 520 and the I-5/Mercer Street interchange.
- Earlier-than-planned Eastside/South Lake Union transit service via the reversible I-5 express lanes connection. The connection could open as early as late 2023 for transit instead of the originally expected opening in 2029.
- A more efficient phasing of SR 520 construction that minimizes contractor overlap in the Montlake area while keeping traffic moving during construction.
The SR 520/I-5 Express Lanes Connection Project’s design was developed through years of coordination between WSDOT, the city of Seattle, and partner transit agencies. Visit the Maps and Drawings tab for renderings of key project elements.
A commitment to equitable contracting
WSDOT is committed to providing equitable contracting opportunities to minority-owned, women-owned, veteran-owned and disadvantaged small businesses (MSVWBEs). Our goal is to provide 26 percent of our transportation projects’ contract value to these firms. See our equal opportunity in contracting webpage for more information and resources for working with WSDOT.
Construction on the SR 520/I-5 Express Lanes Connection Project is expected to last into spring 2024. The work includes building a new, elevated reversible HOV access ramp between SR 520 and the I-5 express lanes, constructing 23 retaining walls, and electrical and real-time traffic signage work. The prime contractor, Walsh Construction, has open contracting opportunities on the project for qualified MSVWBE firms for landscaping, hydroseeding, and Vactor truck operations. Subcontractors interested in working on this project should contact:
The reversible transit/HOV lane initially will open only to transit. Carpools will use the reversible lane following completion of a new Portage Bay Bridge and Roanoke lid.
Project ad date
Start of construction
Estimated project completion
This project is part of the $2 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 and 2022 Move Ahead Washington transportation legislation packages.
Rendering of the new direct connection ramp from SR 520 to the I-5 Express Lanes.
We hosted a virtual public meeting on Aug. 24, 2022. Check out the meeting presentation (PDF 4.19 MB) to catch up on the latest construction updates.
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.