WSDOT has announced the specific shutdown times for what it calls “Realign 99,” the viaduct-to-tunnel transition. Note the actual shutdown is now starting later in the evening than previously announced:
10 p.m. Friday, Jan. 4: Stadium ramps close
Northbound SR 99 on-ramp at South Royal Brougham Way closes (near stadiums; connection to I-90 and I-5).
Southbound SR 99 off-ramp at South Atlantic Street closes (near stadiums; connection to I-90 and I-5).
10 p.m. Friday, Jan. 11: Full SR 99 closure through downtown Seattle begins
SR 99 closes both directions from South Spokane Street to the south end of the Battery Street Tunnel.
Battery Street Tunnel remains open with one lane in each direction. Ramps to and from Western Avenue remain open.
West Seattle Bridge and off-ramps to First Avenue and Fourth Avenue remain open and do not close as part of Realign99.
10 p.m. Friday, Feb. 1: Battery Street Tunnel closes
Battery Street Tunnel closes. All southbound SR 99 traffic must exit at Valley Street. Northbound SR 99 traffic can join highway at Valley Street.
Early February (exact date TBD): New tunnel opens
SR 99 reopens about three weeks after Jan. 11, with highway using new SR 99 tunnel. Alaskan Way Viaduct and Battery Street Tunnel remain closed. One SR 99 off-ramp remains closed (see below).
Approx. 2 weeks later: Final ramp opens
New SR 99 northbound off-ramp to downtown and Alaskan Way (just south of tunnel) opens, about two weeks after SR 99 tunnel opens.
Earlier this week, King County announced the Water Taxi’s extra-service schedule for the shutdown, which will continue running until the spring/summer schedule starts in late March, while also announcing a new shuttle service for part of WS.