Local Information

Construction to start soon on SR 520/I-5 Express Lanes Connection Project in Seattle

Friday, August 20, 2021 - 11:30

Steve Peer, communications, 425-301-2023

New reversible transit lane between highways scheduled to open in 2023

SEATTLE – Crews will break ground as early as next week on a project that will extend State Route 520’s new transit/high occupancy vehicle system to Interstate 5 in Seattle. The new transit/HOV system will provide a dedicated, reversible connection between SR 520 and the I-5/Mercer Street interchange via the I-5 express lanes.

In the coming weeks, crews will add fencing to define the project limits, implement erosion control measures, and confirm utility locations and soil conditions for the upcoming work. The bulk of construction will occur at night or off the roadway and there will be frequent evening and weekend ramp and lane closures, and reductions on SR 520 and I-5.

Once complete, the new reversible lane will work in concert with the I-5 express lanes. When the I-5 express lanes are operating in the northbound direction, the new ramp will connect to eastbound SR 520. The new ramp will connect westbound SR 520 vehicles to the I-5 express lanes when they are operating in the southbound direction.

Initially, only buses will use the connection. The reversible lane will open to carpools when construction of the SR 520 - Portage Bay Bridge and Roanoke Lid Project is complete.

The project also includes:

  • Revising I-5 express lanes to retain the four existing lanes while adding a reversible transit/HOV lane between the I-5/SR 520 interchange and Mercer Street.
  • Modifying an existing ramp for reversible operations between the I-5 express lanes and Mercer Street.

The $68 million SR 520 - I-5 Express Lanes Connection Project, awarded to Walsh Construction earlier this year, is scheduled for completion in late 2023.

This is the second of four SR 520 projects that make up the Rest of the West improvements. The projects were funded in the 2015 Connecting Washington funding package.

More information

A recent WSDOT blog outlines more about the project, future improvements and what to expect during construction.

Get Our Mobile App

  • Our Android and iPhone apps include statewide traffic cameras, travel alerts, mountain pass reports, ferry schedules and alerts, northbound Canadian border wait times and more.