Seattle-area slowdowns ahead from I-405, Highway 18, light rail closures
All lanes of southbound Interstate 405 entering downtown Renton, as well as eastbound Highway 18 beyond Issaquah-Hobart Road, will close this weekend for separate construction jobs, which will generate slowdowns through miles of the Eastside.
Transit riders must also detour around weekend maintenance, blocking Sound Transit's light rail between Rainier Beach and SeaTac/Airport stations.
The I-405 southbound roadwork, between Highway 169 and the Highway 167 interchange, will begin at 12:01 a.m. Saturday and end at 4 a.m. Monday.
The recommended detour route sends drivers off the freeway even farther upstream, at Southport Drive/Exit 5, to wind past downtown Renton, arriving at the big Highway 167 junction via Rainier Avenue South. Exit 4 southbound, a short distance from Highway 169, will be open but prone to serious congestion, as traffic converges from major connecting roads.
Crews will install drainage systems, replace concrete pavement panels and repave the roadway as part of the Washington State Department of Transportation's toll-lane project, on course to finish two years late in 2027. The $705 million job will result in two free lanes and two toll lanes each direction from Renton to Bellevue, connected to other suburban toll lanes.
WSDOT expects a dozen weekends of full-direction or multilane closures in the Bellevue-Renton corridor between now and late fall, said project spokesperson Craig Smiley.
Meanwhile, out in the foothills, eastbound Highway 18 was scheduled to close at 9 p.m. Thursday with at least one lane to reopen by 5 a.m. Monday, from Issaquah-Hobart Road to the Interstate 90 junction in Snoqualmie.
WSDOT urges freight truckers to take I-405 to Highway 900 then eastbound I-90 in Issaquah, or I-405 to eastbound I-90 in Bellevue, as they journey to Snoqualmie Pass - instead of driving along Highway 18, then Issaquah-Hobart Road, which can't withstand truck traffic. The detour has its own flaws, by imposing heavy vehicles on residential segments of Highway 900, that can get congested.
Other limited day and overnight lane reductions are ongoing along Highway 18, as contractors pave eastbound lanes while adding curbs, drains and 1½ miles of new guardrail.
Sound Transit's 1 Line in Tukwila will undergo scheduled rail and power system maintenance, all day Saturday and Sunday, blocking the corridor. Shuttle buses will operate between Rainier Beach, Tukwila International Boulevard, and SeaTac/Airport stations. The rest of the 1 Line will operate normally, with trains arriving every 10 minutes.
A less-disruptive job is planned on the light rail 2 Line in Bellevue between Spring District and Overlake stations, both days from early morning until noon, while new street-crossing pavement is installed. Shuttle buses will go between those stations. Trains west of Spring District will run 20 minutes apart to Seattle and Lynnwood, while those east of Overlake will run every 13 minutes to Redmond.
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This story was originally published April 23, 2026 at 4:59 PM.