Eastbound I-90 drivers will see delays and detours this weekend, as cars are funneled into the express lanes for a construction project.

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Drivers going east on I-90 this weekend will be funneled into the express lanes, to allow construction in the regular eastbound roadway.

Backups from this detour likely will spill into the northbound lanes of I-5 at Sodo, as well as the collector-distributor lanes of southbound I-5 in downtown Seattle.

The lane closures will last from 11 p.m. Friday until 5 a.m. Monday. This is the first of some 30 work closures, says the Washington State Department of Transportation. The state is building bus and carpool lanes next to the regular lanes, a $188 million program, so the express lanes can be given over to Sound Transit light rail construction in 2017. Train service to Bellevue and Overlake is estimated to begin in 2023.

This weekend’s work will happen within the Mount Baker Tunnel and the Mercer Island lids. Crews from IMCO General Construction will be cutting concrete, installing barrier, and building foundations for ventilation fans, said spokeswoman Annie Johnson. In future weeks, contractors will be updating the fire suppression systems and the lighting. There are 30 planned weekend closures in the west- and eastbound directions.

The big challenge will be narrowing the I-90 traffic at north Beacon Hill in Seattle, so vehicles can enter through the single entrance lane into the I-90 express lanes. “We are expecting to see some backups,” Johnson said.  Lane closures will begin at about  I-5, probably spreading the congestion southward.

Mercer Island drivers will be able to enter the general lanes at Island Crest Way, headed toward Bellevue.  Drivers entering from Rainier Avenue South will find the usual ramps closed, so they must follow detour signs via South Dearborn Street.