Infrastructure

I-405, SR 9 closures for construction

Saturday, August 22, 2026

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I-405 and SR 9 will see multiple lane closures this week for construction projects, according to Washington State Department of Transportation (WSDOT) updates. The left express toll lane on northbound I-405 between Northeast 132nd Street and SR 522 will close nightly from 8 p.m. Wednesday through Saturday, with additional closures on southbound I-405 lanes from Friday evening through Saturday morning. SR 9 near Kalloch Road will be reduced to a single lane until Sept. 14 for fish passage construction, with alternating traffic at milepost 49 until Sept. 3.

WSDOT notes that construction on I-405 from Aug. 24-26 will include rolling slowdowns and lane closures for PSE utility work and pavement repair. SR 9 between Park and Doran roads will have flaggers alternating traffic daily through Aug. 27 for paving, weather permitting. Delays are expected throughout these projects, with specific dates and times provided in the WSDOT updates.

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

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I-405 and SR 9 will see multiple lane closures this week for construction projects“405: The left express toll lane of northbound I-405 between Northeast 132nd Street (milepost 21.43) and SR 522 (milepost 23.5) will be closed nightly from 8 p.m. Wednesday, August 19 to 5 a.m. Friday, August 21 and overnight from 8:30 p.m. Friday, August 21 and 9 a.m. Saturday, August 22.”
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The left express toll lane on northbound I-405 between Northeast 132nd Street and SR 522 will close nightly“405: The left express toll lane of northbound I-405 between Northeast 132nd Street (milepost 21.43) and SR 522 (milepost 23.5) will be closed nightly from 8 p.m. Wednesday, August 19 to 5 a.m. Friday, August 21 and overnight from 8:30 p.m. Friday, August 21 and 9 a.m. Saturday, August 22.”
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The closure on northbound I-405 will be from 8 p.m. Wednesday through SaturdayNo usable supporting receipt — unverified.
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Additional closures on southbound I-405 lanes will be from Friday evening through Saturday morning“405: Friday, August 21 to the morning of Saturday, August 22: Up to two lanes of southbound I-405 between milepost 18.11 and milepost 16.45 will be closed from 11:30 p.m. - 5 a.m.”
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SR 9 near Kalloch Road will be reduced to a single lane until Sept. 14“009: SR 9 is reduced to a single lane near Kalloch Road (MP 59) with a signal alternating northbound and southbound traffic through a bypass road for 42 days, until Sept. 14 for fish passage construction.”
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The reduction to a single lane on SR 9 is for fish passage construction“009: SR 9 is reduced to a single lane near Kalloch Road (MP 59) with a signal alternating northbound and southbound traffic through a bypass road for 42 days, until Sept. 14 for fish passage construction. Expect delays in the area.”
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Alternating traffic will be at milepost 49 on SR 9 until Sept. 3“009: Northbound and southbound traffic will alternate from 10 a.m. to 4 p.m. daily Mondays through Thursday through Thursday, Sept. 3, just south of Mount Vernon Big Lake Road (milepost 49) for fish passage construction. Expect delays in the area.”
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Construction on I-405 from Aug. 24-26 will include rolling slowdowns and lane closures“405: Nightly from 11:59 p.m. to 4 a.m. the next day beginning Monday, Aug. 24 to 4 a.m. Wednesday, Aug. 26, expect intermittent rolling slowdowns on both directions of Interstate 405 from Northeast 145th Street (milepost 21) to Coal Creek Parkway/Newport Way (milepost 10) for PSE utilities work.”
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The construction on I-405 from Aug. 24-26 is for PSE utility work and pavement repair“405: Nightly from 11:59 p.m. to 4 a.m. the next day beginning Monday, Aug. 24 to 4 a.m. Wednesday, Aug. 26, expect intermittent rolling slowdowns on both directions of Interstate 405 from Northeast 145th Street (milepost 21) to Coal Creek Parkway/Newport Way (milepost 10) for PSE utilities work.”
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SR 9 between Park and Doran roads will have flaggers alternating traffic daily through Aug. 27“009: Flaggers and pilot vehicles will alternate northbound and southbound SR 9 traffic from 6 a.m. to 6 p.m. daily Monday through Thursday, Aug. 24-27, between Park and Doran roads (mileposts 68-69) for grinding and paving. Expect delays. This work needs dry weather and may be rescheduled.”
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The paving on SR 9 between Park and Doran roads is weather permittingNo usable supporting receipt — unverified.
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Delays are expected throughout these projectsNo usable supporting receipt — unverified.
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Specific dates and times for delays are provided in the WSDOT updates“405: The left express toll lane of northbound I-405 between Northeast 132nd Street (milepost 21.43) and SR 522 (milepost 23.5) will be closed nightly from 8 p.m. Wednesday, August 19 to 5 a.m. Friday, August 21 and overnight from 8:30 p.m. Friday, August 21 and 9 a.m. Saturday, August 22.”