This map shows the projects that will replace SR 99 through Seattle.
Building a new State Route 99 through Seattle
Major elements of the program include:
- A two-mile-long tunnel beneath downtown Seattle.
- A mile-long stretch of new highway that connects to the south entrance of the tunnel, near Seattle’s stadiums.
- A new overpass at the south end of downtown that allows traffic to bypass train blockages near Seattle’s busiest port terminal.
- Demolition of the viaduct’s downtown waterfront section.
- A new Alaskan Way surface street along the waterfront that connects SR 99 to downtown.
Our schedule page includes a list of all 30 projects that are led or funded by the state as part of this effort.
The SR 99 tunnel changes the way traffic uses SR 99 in Seattle. Drivers approaching the tunnel from either direction will face a choice depending on their destination: use the tunnel to bypass downtown or exit to city streets and head into downtown. At the tunnel’s north end, downtown access will be similar to today, with on- and off-ramps near Seattle Center. From the south, new on- and off-ramps will connect SR 99 to downtown via the new waterfront street. The SR 99 tunnel opened on Feb. 4, 2019.
We work closely with residents and businesses near the viaduct to help them through construction. Milepost 31, our award-winning project information center, helped attract visitors and business to Pioneer Square for six years during project construction. WSDOT’s parking mitigation program focuses on strategies that offset construction-related on-street parking impacts in Pioneer Square and the waterfront neighborhoods.
The Alaskan Way Viaduct Replacement Program is a partnership between the following public agencies:
The Federal Highway Administration (FHWA) is responsible for ensuring that the viaduct replacement projects meet federal regulations.
The Washington State Department of Transportation (WSDOT) owns SR 99 and the viaduct. The agency is responsible for highway inspections and major maintenance, and for ensuring that state regulations are followed.
King County is responsible for implementing transit changes and improvements associated with the program.
The Port of Seattle relies heavily on the SR 99 corridor and has committed $300 million in funding to the program.
The City of Seattle is responsible for viaduct traffic operations and minor maintenance. In addition, the city owns and maintains Alaskan Way, the area underneath the viaduct and many of the utilities located in the project area.