Drivers will encounter highway and interstate road closures across the Seattle area this weekend.

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Northbound Highway 99 in Sodo will close this weekend, restricting access to the Alaskan Way Viaduct, while crews install interchange signs for the deep-bore tunnel that opens in early February. The viaduct closes Jan. 11 to be demolished next year.

This weekend’s schedule divides into two phases, as the teams work their way from north to south:

  • From 9 p.m. Friday until late Saturday night, the northbound direction closes from the West Seattle Bridge to the south end of the Battery Street tunnel. Sign work will also block the frontage road and northbound onramp that serves Royal Brougham Way South and South Atlantic Street.
  • From late Saturday until 5 a.m. Monday, drivers regain the entrance ramp from Royal Brougham Way South onto the northbound viaduct, but not from South Atlantic Street — to help with Seahawks game traffic Sunday. The ramp from the West Seattle Bridge onto northbound Highway 99 will remain closed until Monday morning. Mainline traffic from points south must exit by Spokane Street.

Another disruption happens south of Seattle in Renton. The southbound segment of Highway 167 from the I-405 interchange to South 180th Street — and three onramps that feed or cross Highway 167 there — will close from 8:30 p.m. Friday until 5 a.m. Monday. Detour signs will shift traffic, in some cases for 2 miles. The shutdowns allow installation of fish-migration culverts below the freeway, related to the big 167/405 high-occupancy lane overpass that opens next year.

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On the Eastside, westbound I-90 will be reduced to two lanes Saturday from 6 a.m. to 11:59 p.m., to replace 14 drainage lids and utility covers between Bellevue Way and the floating bridge.

And in downtown Seattle, southbound I-5 will close for concrete repaving twice overnight, and vehicles will be detoured through collector-distributor lanes (on the right side). The detours extend from 11 p.m. Saturday to 5 a.m. Sunday, and 11 p.m. Sunday until 4:30 p.m. Monday.

King County Metro Transit will add service on 20 routes this weekend and Monday, while revising several others in suburbs as well as Seattle. Some corridors will increase to daytime service every 10 minutes, while peak-time buses arrive every five minutes or sooner on the Aurora Avenue E Line, the area’s busiest at 18,000 daily passengers.

Night service will grow on the F Line from Burien to Renton. New operating hours are fueled by gains in sales-tax income, by a Seattle $60 car-tab fee and an Amazon donation that covers 22 daily bus runs. Changes are posted online and on red paper schedules.

Finally, the I-90 bus station over Rainier Avenue South will close Saturday, so Sound Transit can build its Judkins Park Station there for light rail trains in 2023. Express bus 550 and 554 and several Metro lines will detour.