Westbound I-90 will be funneled into one lane at Bellevue Way this weekend.

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Weekend traffic delays await drivers approaching westbound Interstate 90, which will tighten to just one lane at the Bellevue Way interchange, from 11 p.m. Friday until 5 a.m. Monday.

Traffic will be funneled into the I-90 express lanes, while Mercer Island traffic can exit at East Mercer Way. Delays there often spread to I-405.

Meanwhile in Seattle, the ramp from Northeast 50th Street onto southbound I-5 will close Sunday morning, from 5 a.m. to 10:30 a.m., while city crews remove debris.

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The city reports that in March it picked up 49 tons of rubbish, including biohazards, along the freeway, mainly from homeless camps. Another 108 tons of trash and surface soil were removed in early April beneath the Spokane Street Viaduct.

In other congestion forecasts, the Washington State Spring Fair in Puyallup will add traffic on Highways 161 and 167 all weekend, while the Cherry Blossom and Japanese Cultural Festival at Seattle Center will attract about 14,000 people.

The March for Science on Saturday begins on Capitol Hill with speeches in Cal Anderson Park at 10 a.m. The walk will start around noon and end in Seattle Center.

Saturday is Earth Day, creating a second impetus besides lousy traffic to burn less fossil fuel.

Only two of the planned partial closures remain for I-90 — eastbound from May 5-8, and westbound May 12-15.

During a total of 30 weekends, contractors on I-90 have been paving or striping new high-occupancy lanes, updating the fire-sprinkler and lighting systems, and installing huge fans within the Mount Baker Tunnel to remove smoke in emergencies. That multiyear, $283 million projectis a prerequisite for kicking buses and Mercer Island traffic out of the express lanes, allowing Sound Transit to replace those with light-rail tracks.

The express lanes close entirely June 3 and will be unavailable to the public until train passengers travel across Lake Washington in 2023.

The Washington State Department of Transportation urges people to check traffic conditions online before motoring.