Building New State Route 99 through Seattle
The Alaskan Way Viaduct, an elevated section of State Route 99 in Seattle, was built in the 1950s, and decades of daily wear and tear have taken their toll on the structure. Because of the viaduct’s age and vulnerability to earthquakes, replacing it is critical to public safety.
The Alaskan Way Viaduct Replacement Program includes 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.
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.