Eastbound SR 18 will close for construction, joining I-405 and I-5 lane disruptions; expect widespread congestion and detours throughout Seattle this weekend.
RENTON, Wash. — A major closure on State Route 18 is setting the stage for a difficult weekend, with multiple construction projects happening at once.
The eastbound lanes of SR 18 will fully close as early as 9 p.m. Thursday, April 23, between Deep Creek and the I-90 interchange. The closure is part of ongoing improvements to the I-90/SR 18 interchange.
Crews have already reduced eastbound SR 18 to a single lane earlier this week while removing thousands of feet of guardrail and concrete barriers in preparation for the work.
At least one lane of SR 18 is expected to reopen by 5 a.m. Monday, April 27, but additional lane closures will continue through April 30 as crews reinstall guardrails, curbing and stormwater systems.
Freight drivers are being warned to avoid Issaquah-area surface streets, including Issaquah-Hobart Road, which are not designed for heavy truck traffic. Instead, officials recommend using a detour using SR 169 to northbound Interstate 405, then eastbound SR 900 to I-90.
That closure will overlap with another major disruption the following day.
Southbound I-405 in Renton will shut down between SR 169 and SR 167 beginning as early as 11:59 p.m. Friday, April 24, and remain closed through 4 a.m. Monday, April 27. Crews will use the time to install drainage, replace concrete panels and repave sections of the roadway as part of a widening and express toll lane project. A signed detour will be in place.
All of this comes as work continues on I-5 through Seattle, where two northbound lanes remain closed across the Ship Canal Bridge for major repairs.
The overlapping closures are expected to create widespread congestion across the region, not just near the construction zones.
The Washington State Department of Transportation says drivers should plan for delays along SR 18 detour routes, heavier traffic in both directions on I-405, and increased congestion throughout Seattle as I-5 capacity remains limited. Transportation officials say backups could spill onto local roads and into areas that don’t typically see freeway traffic.
WSDOT is urging travelers to plan ahead, allow extra time and consider alternatives like transit, park-and-ride options or adjusting travel schedules.
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