Infrastructure

I-405, SR 20 closures this week

Monday, August 31, 2026

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Starting Thursday evening, Sept. 3, up to two lanes of southbound I-405 from milepost 12 to Coal Creek Parkway Southeast will close overnight until 5 a.m. Friday, Sept. 4, according to WSDOT.

State Route 20 will alternate traffic with flaggers daily from Swin Slough Bridge to Laconner Whitney Road/Bay View Road beginning Aug. 21 for Anacortes utilities work, with no end date specified in the public notice. Other closures include I-5 fish passage construction near Alger/Lake Samish Road through Sept. 10 and SR 4 work between 50th and 42nd Avenues weekdays until Sept. 11.

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

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Starting Thursday evening, Sept. 3, up to two lanes of southbound I-405 from milepost 12 to Coal Creek Parkway Southeast will close overnight“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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The closure of southbound I-405 will continue until 5 a.m. Friday, Sept. 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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State Route 20 will alternate traffic with flaggers daily 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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The traffic alternation on State Route 20 will begin on Aug. 21“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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The traffic alternation on State Route 20 is for Anacortes utilities work“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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No end date is specified in the public notice for the traffic alternation on State Route 20No usable supporting receipt — unverified.
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I-5 fish passage construction near Alger/Lake Samish Road will continue through Sept. 10No usable supporting receipt — unverified.
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SR 4 work between 50th and 42nd Avenues will occur weekdays until Sept. 11“004: Monday, Aug. 17 through Friday, Sept. 11: A single lane in both directions of SR 4 between 50th Avenue (milepost 56.4) and 42nd Avenue (milepost 57.2) will be closed weekdays from 7:30 a.m. to 5 p.m., for buried gas main line extension work.”