Major projects

View current major projects, which are investments we make with local partners to address safety, congestion, mobility for all users and/or fish passage responsibilities.

Map showing Alaskan Way Viaduct program limits along Seattle waterfront, south end near stadiums and north end near Seattle Center

Alaskan Way Viaduct Replacement Program

The Alaskan Way Viaduct Replacement Program consists of 30 projects led by the Washington State Department of Transportation, King County, the City of Seattle and the Port of Seattle. The Federal Highway Administration is a partner in this effort.

Ferry system electrification

Washington State Ferries (WSF) will convert our ferry system, the largest in the country, to hybrid-electric power by 2040 following mandates from the Washington legislature and governor. Transitioning to a hybrid-electric fleet is necessary to reduce emissions, ensure resiliency, and reduce operations and maintenance costs.

As the biggest contributor of greenhouse gas emissions among Washington state agencies, WSF burns approximately nineteen million gallons of diesel fuel to support nearly twenty million passengers every year. This innovative electrification program will drastically reduce greenhouse gas emissions and save millions in fuel costs.

A map showing the I-405/SR 167 Corridor.

I-405/SR 167 Corridor Program

The I-405/SR 167 Corridor Program stems from the I-405 Master Plan and SR 167 Master Plan, foundational documents that guide project development, funding and delivery. The I-405 Master Plan alone includes over 150 projects designed to improve travel between Lynnwood and the Renton/Tukwila area. When combined with SR 167, this north-south corridor forms a 50+-mile transportation system providing travelers with a reliable trip in the express toll lanes, regular lanes and high-capacity transit (bus rapid transit).

Aerial photo of a congested I-5 through JBLM

I-5 - Mounts Road to Thorne Lane I/C - Corridor Improvements

In July 2015, the Washington State Legislature included $495 million to fund the I-5 Mounts Road to Thorne Lane Interchange - Corridor Improvements project, as part of the Connecting Washington transportation revenue package. The project is funded through a 10 year period, from 2015-2025.

I-5 - SR 16 Tacoma/Pierce County HOV Program

The Tacoma/Pierce County HOV Program is a series of projects, spanning over 20 years, that build high-occupancy-vehicle (HOV) lanes on I-5, SR 16 and SR 167 in Pierce County.

I-90 - Snoqualmie Pass East Project

The I-90 Snoqualmie Pass East Project improves 15 miles from Hyak to Easton. Phases 1 and 2 from Hyak to the Stampede Pass interchange are complete. Phase 3 is underway.

Steel truss bridge over a river with a cityscape background during a sunset or sunrise, and the IBR in the top right corner.

Interstate Bridge Replacement Program

The Interstate Bridge Replacement program is a bi-state effort with the Washington State Department of Transportation and the Oregon Department of Transportation to replace the aging Interstate Bridge along I-5 over the Columbia River between Portland and Vancouver. The program will build a new, seismically resilient multimodal bridge, reconfigure seven closely spaced interchanges in the five-mile corridor, extend light rail across the river, and add express bus on shoulder over the bridge. IBR program investments focus on safety and earthquake resilience, improve reliability, improve bike and pedestrian pathways, improve freight movement, and add public transit options for travelers in the corridor.

North Spokane Corridor

The North Spokane Corridor (NSC) is a 10.5-mile multi-modal corridor. When complete, the NSC will be a 60-mile per hour, north/south limited access facility that connects I-90 at the south (just west of the existing Thor/Freya interchange) and connects to US 2 (at Farwell Road) and US 395 (at Wandermere) on the north end. Various stages of construction remain to complete the project.

7 miles are now completed with only 3.5 left to go.

Puget Sound Gateway Program

The Puget Sound Gateway Program combines the SR 509 Completion Project in King County and the SR 167 Completion Project in Pierce County to complete critical missing links in Washington state's highway and freight network. These projects build important new connections to the state's ports, improve the movement of freight and reduce congestion on local roads and highways. Both projects have multimodal benefits and together create 13.8 miles of new bike/pedestrian paths and 4.5 miles of new sidewalks.

Cars wait for the ferry on the Fauntleroy Ferry Terminal dock

SR 160 - Fauntleroy Terminal - Trestle & Transfer Span Replacement

The SR 160 - Fauntleroy Terminal - Trestle & Transfer Span Replacement project will replace the aging Fauntleroy ferry terminal to maintain safe and reliable ferry service for people who travel between West Seattle, Vashon Island, the Kitsap Peninsula and beyond. The terminal is an essential transportation hub that serves more than 3 million riders per year, including people who board ferries by walking, biking, driving and riding transit. The terminal faces several challenges. Built in the 1950s, parts of the terminal are aging, seismically vulnerable and overdue for replacement.

Project news: WSF plans to begin construction of intersection improvements at Fauntleroy Way SW in fall 2025 and complete construction by early 2026. This fall, crews will complete early surveying work and traffic data collection near the intersection.

Panorama view of SR 520 across Union Bay. In the foreground is a work zone where crews are construction a new, parallel bridge. The highway is surrounded by a residential neighborhood.

SR 520 Bridge Replacement and HOV Program

The SR 520 Bridge Replacement and HOV Program enhances travel safety and mobility with modern, structurally stronger bridges, as well as substantial transit and roadway improvements along this urban corridor. Built in stages, the improvements extend from I-405 in Bellevue to I-5 in Seattle.