Highway construction, utility work and a regular inspection of the Alaskan Way Viaduct will close portions of SR 99 through Seattle this weekend. Lane closures along both directions of SR 99 begin at 7 p.m. Friday, March 27. By 10 p.m., SR 99 will be closed between the south end of the Battery Street Tunnel and Valley Street until 5 a.m. Monday, March 30.
SR 99 closure details
7 p.m. Friday, March 27, until 5 a.m. Monday, March 30
- Seattle Public Utilities crews will close two northbound lanes and one southbound lane of SR 99 between Ward Street and Highland Drive from 7 p.m. Friday to 5 a.m. Monday.
- WSDOT and SDOT contractor crews will close SR 99 between the Battery Street Tunnel and Valley Street from 10 p.m. Friday to 5 a.m. Monday.
6 a.m. to 6 p.m. Saturday, March 28, and Sunday, March 29
- WSDOT bridge inspection crews will conduct a scheduled inspection of the Alaskan Way Viaduct between South Spokane Street and the Battery Street Tunnel.
Westbound I-90 closure
The SR 99 closures are part of a busy weekend of highway construction in the region. Drivers heading across Lake Washington from the Eastside will see westbound Interstate 90 detoured to the express lanes as crews upgrade tunnel operations systems inside the westbound Mount Baker and Mercer Island tunnels.
11 p.m. Friday, March 27, until 5 a.m. Monday, March 30
- Contractor crews will shift all westbound I-90 traffic between Bellevue Way and Rainier Avenue South to the express lanes from 11 p.m. Friday to 5 a.m. Monday.
- Drivers wishing to access Mercer Island will need to exit westbound I-90 at East Mercer Way. There are no westbound exits to Mercer Island from the express lanes.
- Those wishing to travel from Mercer Island to Seattle should enter the express lanes at 77th Avenue Southeast or Island Crest Way.
- Westbound I-90 drivers will be unable to exit to Rainier Avenue South and should follow the signed detour via Fourth Avenue South and South Dearborn Street.
- Drivers needing to transport flammable materials westbound across Lake Washington must use alternate routes such as Interstate 405 or state routes 520 or 522.