Flying out this week? Plan on late night delays to Sea-Tac Airport
Mar 18, 2025, 2:30 PM
People sit in the central terminal looking out towards Alaska Airline planes at Seattle-Tacoma International Airport. (Photo: Kent Nishimura via Getty Images)
(Photo: Kent Nishimura via Getty Images)
Those using the Seattle-Tacoma (Sea-Tac) International Airport this week should pack in some extra travel time.
The Washington State Department of Transportation (WSDOT) will have lane and ramp closures across three major highways near the airport this week, potentially adding more time to the commute. State Route 99 (SR 99), State Route 509 (SR 509) and Interstate-5 (I-5) will all have lane and/or ramp closures beginning as early as 8 p.m. nightly.
Contractors on I-5 will use the lane closures for pavement work. The ramp closures are needed for striping the roadway and installing concrete safety barriers.
I-5 lane closures
- Tuesday, March 18, through the morning of Wednesday, March 19 — from 11:59 p.m. to 4 a.m. — up to four lanes of northbound I-5 will close overnight between SR 516 (Exit 149) and South 200th Street/Military Road South (Exit 151).
- Wednesday, March 19, through the morning of Thursday, March 20 — from 8 p.m. to 4:30 a.m. — up to two lanes of northbound I-5 will close overnight between SR 516 (Exit 149) and South 200th Street/Military Road South (Exit 151).
- Wednesday, March 19, through the morning of Thursday, March 20 — from 11:30 p.m. to 6 a.m. – up to two lanes of southbound I-5 will close overnight between South 200th Street/Military Road South (Exit 151) and SR 516 (Exit 149).
I-5 ramp closures
- Monday, March 17, through the morning of Friday, March 21 — from 9:30 p.m. to 3:30 a.m. — the northbound I-5 off-ramp to SR 516 will close nightly. A signed detour will be in place.
- Monday, March 17, through the morning of Friday, March 21 — from 11 p.m. to 3:30 a.m. — the northbound I-5 on-ramp from SR 516 will close nightly. A signed detour will be in place.
SR 509 lane closure
- Monday, March 17, through the morning of Thursday, March 20 — from 8 p.m. to 5 a.m. – one lane in both directions of SR 509 will close nightly between Des Moines Memorial Drive South and South 160th Street.
SR 509 ramp closure
- Monday, March 17, through the morning of Thursday, March 20 — from 8 p.m. to 5 a.m. — the southbound SR 509 off-ramp to South 160th Street will close nightly. A signed detour will be in place.
Contract work on SR 99 will use lane closures to continue working on new Americans with Disabilities Act (ADA) sidewalks. Later this spring, crews will repave this section.
SR 99 lane closure
- Monday, March 17, through the morning of Friday, March 21 — from 8 p.m. to 5 a.m. — both directions of SR 99 will close a lane between South 200th Street and SR 516, in Des Moines. This work is part of the sidewalk improvement project.
Additionally, the Port of Seattle has work scheduled this week on the arrivals and departures decks, with intermittent closures between 8 p.m. and 8:30 a.m. through Friday.
Nate Connors is a traffic reporter for KIRO Newsradio. Follow him on X. Submit news tips here.
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