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Infrastructure

I-405, I-5, SR 20 closures announced for Tri-Cities

Saturday, August 29, 2026

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Multiple Washington State Department of Transportation (WSDOT) projects will impact Tri-Cities area highways beginning late August and continuing through mid-September.

I-405 will see multiple overnight closures, including a full northbound closure from Northeast 70th Place to Northeast 85th Street from 11 p.m. Friday, Aug. 28 to 5 a.m. Monday, Aug. 31. Southbound I-405 will close up to four lanes from milepost 14. 25 to 12. 5 on Aug. 28-29 and up to two lanes from milepost 12 to Coal Creek Parkway Southeast on Sept. 3-4.

I-5 will be reduced to a single lane nightly from 8 p.m. to 5 a.m. near Alger/Lake Samish Road (exit 240) from Aug. 31 through Sept. 4. State Route 20 will alternate traffic with flaggers daily except weekends from Swin Slough Bridge to Laconner Whitney Road/Bay View Road. State Route 599 will close the right lane and off-ramp to Tukwila International Boulevard on Aug. 28-29, and State Route 547 will alternate traffic weekdays from 9 a.m. to 3 p.m. through Sept. 4 for PSE utilities work.

📄 Source: WSDOT — Highway Construction & Closures — https://wsdot.wa.gov/travel/road-construction

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Multiple Washington State Department of Transportation (WSDOT) projects will impact Tri-Cities area highwaysNo usable supporting receipt — unverified.
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The impact of WSDOT projects on Tri-Cities area highways will begin late AugustNo usable supporting receipt — unverified.
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The impact of WSDOT projects on Tri-Cities area highways will continue through mid-SeptemberNo usable supporting receipt — unverified.
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I-405 will see multiple overnight closures“405: Up to two lanes of southbound I-405 from milepost 12 to Coal Creek Parkway Southeast (milepost 10) will be closed overnight, 9 p.m. Thursday, Sept. 3 – 5 a.m. Friday, Sept. 4. 405: Up to four lanes of southbound I-405 from milepost 14.25 to milepost 12.5 will be closed overnight, 10 p.m. Friday, Aug. 28 – 8 a.m. Saturday, Aug. 29. 405: Up to three lanes of northbound I-405 will close from the Northeast 85th Street on-ramp to Northeast 100th Street from 11 p.m. Friday Aug. 28 to 5 a.m. Monday, Aug. 31. A signed detour will be in place. 405: All lanes of northbound I-405 will close from Northeast 70th Place to Northeast 85th Street from 11 p.m. Friday Aug. 28 to 5 a.m. Monday, Aug. 31. A signed detour will be in place.”
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I-405 will have a full northbound closure from Northeast 70th Place to Northeast 85th Street“405: All lanes of northbound I-405 will close from Northeast 70th Place to Northeast 85th Street from 11 p.m. Friday Aug. 28 to 5 a.m. Monday, Aug. 31. A signed detour will be in place.”
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The full northbound closure on I-405 will be from 11 p.m. Friday, Aug. 28 to 5 a.m. Monday, Aug. 31“405: All lanes of northbound I-405 will close from Northeast 70th Place to Northeast 85th Street from 11 p.m. Friday Aug. 28 to 5 a.m. Monday, Aug. 31. A signed detour will be in place.”
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Southbound I-405 will close up to four lanes from milepost 14.25 to 12.5 on Aug. 28-29“405: Up to four lanes of southbound I-405 from milepost 14.25 to milepost 12.5 will be closed overnight, 10 p.m. Friday, Aug. 28 – 8 a.m. Saturday, Aug. 29.”
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Southbound I-405 will close up to two lanes from milepost 12 to Coal Creek Parkway Southeast on Sept. 3-4“405: Up to two lanes of southbound I-405 from milepost 12 to Coal Creek Parkway Southeast (milepost 10) will be closed overnight, 9 p.m. Thursday, Sept. 3 – 5 a.m. Friday, Sept. 4.”
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I-5 will be reduced to a single lane nightly from 8 p.m. to 5 a.m. near Alger/Lake Samish Road (exit 240)“005: The northbound and southbound I-5 will be reduced to a single lane from 8 p.m. to 5 a.m. nightly Monday, Aug. 31, through Friday morning, Sept. 4, near Alger/Lake Samish Road (exit 240) for fish passage construction.”
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The single lane reduction on I-5 will be from Aug. 31 through Sept. 4“005: The northbound and southbound I-5 will be reduced to a single lane from 8 p.m. to 5 a.m. nightly Monday, Aug. 31, through Friday morning, Sept. 4, near Alger/Lake Samish Road (exit 240) for fish passage construction.”
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State Route 20 will alternate traffic with flaggers daily except weekends from Swin Slough Bridge to Laconner Whitney Road/Bay View Road“020: Daily (except Saturday, Sunday) beginning Aug. 21 until further notice: State Route 20 traffic will alternate with flaggers from the Swin Slough Bridge (milepost 50) to Laconner Whitney Road/Bay View Road (milepost 53) for city Anacortes utilities work.”
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State Route 599 will close the right lane and off-ramp to Tukwila International Boulevard on Aug. 28-29“599: From 9 p.m. Friday, Aug. 28 to 5 a.m. Saturday, Aug. 29, the right lane of northbound State Route 599 and the off-ramp to Tukwila International Boulevard (milepost 1) will close for maintenance.”
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State Route 547 will alternate traffic weekdays from 9 a.m. to 3 p.m. through Sept. 4 for PSE utilities work“547: Weekdays from 9 a.m. to 3 p.m. beginning Monday, Aug. 24 until noon Friday, Sept. 4, State Route 547 traffic will alternate with flaggers from State Route 542 (milepost 0) to Frost Road (milepost 6) will close for PSE utilities work.”