Seafair and I-5, I-90 closures could snarl weekend traffic

Highway closures and Seafair events are expected to clog Seattle-area streets and highways in a big way this weekend.

The annual Seafair Torchlight Parade and Run will be Saturday evening, drawing more than 300,000 people to downtown Seattle. Routes for both will require street closures.

The Seafair Torchlight Run — both a 5K run and walk and an 8K run — is expected to draw 4,800 participants beginning at 6:30 p.m. The route starts at Ninth Avenue North and Republican Street.

For the race, the Alaskan Way Viaduct's northbound lanes will be closed from just south of the West Seattle Bridge to Roy Street from 5:30 to about 7 p.m.

Meanwhile, an estimated 300,000 or more people are expected to line the route for the Seafair Torchlight Parade, scheduled for 7:30-11 p.m. The parade on Fourth Avenue starts near Seattle Center and ends in the north lot of Qwest Field.

There will be parking restrictions along the route.

I-5 and I-90 closures

Also this weekend, the state Department of Transportation will close part of Interstate 5 in Seattle and Interstate 90 between Seattle and Mercer Island so maintenance crews can test the fire-suppression system along I-5 beneath the Washington State Convention Center and inspect sign bridges over I-90.

• Interstate 5: All lanes of southbound I-5 were to reopen at 4 a.m. Saturday after Friday's late-night closure downtown. The I-5 express lanes are to remain open for southbound traffic until noon Saturday.

• Interstate 90: Crews will close eastbound I-90 on Saturday and westbound I-90 on Sunday — between Rainier Avenue and East Mercer Way — to inspect more than a dozen sign bridges.

The eastbound I-90 mainline will be closed from midnight Friday to 10 a.m. Saturday, between Rainier Avenue and East Mercer Way, as well as the Rainier Avenue and Island Crest Way onramps to eastbound I-90. All drivers will be diverted onto the express lanes.

Crews will close the westbound I-90 mainline from midnight Saturday to 10 a.m. Sunday between East Mercer Way and Rainier Avenue. Drivers will be diverted onto the express lanes.

The Island Crest Way and 77th Avenue Southeast ramps to the express lanes will remain open; all other westbound ramps on Mercer Island will be closed.

The full closures are needed so crews can maneuver large pieces of equipment across the roadway.