Eastbound I-90 to close Saturday for a Mercer Island restripe

Traffic Lab is a Seattle Times project that digs into the region’s transportation issues to explore the policies and politics that determine how we get around and how billions of dollars in public money are spent.

A lane-painting job on Mercer Island will close eastbound Interstate 90 across Lake Washington all day Saturday, and obstruct regional freeway access as far back as Interstate 5 in Sodo.

Traffic jams and delays are likely, state officials warn.

The work is scheduled from 11 p.m. Friday until 6 a.m. Sunday. It conflicts with a Sounders FC home match Saturday afternoon at Lumen Field, when Eastside drivers and buses must detour via Highway 520 or Interstate 405 to get home. The I-90 westbound lanes and walk-bike trail will remain open.

Workers will paint lane stripes to guide traffic around a broken expansion joint, where drivers go from land onto the I-90 East Channel Bridge, between Mercer Island and Bellevue. Since January, only three lanes have been allowed through the area, where the damaged piece was cordoned off.

The Washington State Department of Transportation has decided to block the ramps from I-5 in Seattle onto I-90 during this weekend’s operation.

A short eastbound passage will remain open to reach the I-90 Rainier Avenue exit, but to get there drivers must ascend from Sodo surface streets and Edgar Martinez Drive. No eastbound traffic will cross Lake Washington.

Such a strategy is designed to avert traffic clogs, and rear-end crash risk, if thousands of unaware drivers flooded the I-90 lanes as usual, thinking they can reach Bellevue. In September 2022, a communication breakdown between WSDOT and the public resulted in westbound drivers stuck in a kind of dead-end for hours on Mercer Island, during a construction closure.

Drivers leaving Mercer Island eastbound Saturday must take the East Mercer Way onramp to reach I-90.

Once the roadway reopens Sunday morning, there will be four 10-foot-wide eastbound lanes, compared with the standard 12 feet, along with a reduced speed limit of 45 mph. Also, a concrete barrier and collision-impact absorbers, between lanes, will keep tires from striking the damaged metal.

The traffic mess is another byproduct of Washington state’s failure to adequately fund highway maintenance in the ’00s and ’10s.

Two expansion joints (each with two halves) at East Channel Bridge were installed in 1989 and are past their normal life, but WSDOT tried to wring more years from them because of a shortage of preservation money, spokesperson James Poling said.

For years, state Transportation Secretary Roger Millar has warned about a “glide path to failure,” because state budgets cover just one-third of what he considers a $1.5 billion yearly need for major highway maintenance. Lawmakers added $100 million this month to the former $495 million allotment.

A joint replacement piece is being designed, and won’t be installed until next year, Poling said. Three other halves, scheduled to be replaced in 2027, will be moved two years sooner into 2025, he said. That job will cause new traffic disruptions.