Extended overnight lane reductions and ramp closures planned on I-405 in Bellevue Sept. 15-18

Significant delays expected during emergency repairs; please plan ahead, consider altering travel plans

BELLEVUE – Travelers on the Eastside should prepare for extended overnight lane reductions and ramp closures on Interstate 405 starting the night of Thursday, Sept. 15, as crews make emergency repairs. The work also will include a 23-hour full closure of I-405, with ramps used as detours.

Crews working for the Washington State Department of Transportation will excavate and replace a damaged culvert under I-405 near the 112th Avenue Southeast/Lake Washington Boulevard Southeast (Exit 9) interchange. In spring 2022, WSDOT discovered the failed culvert under mainline I-405 near the Newport Hills Park and Ride in Bellevue. The collapsed culvert resulted in an approximately 15-foot-deep sinkhole in the park and ride and has the potential to cause similar sinkholes under mainline I-405.

The repair work will begin 11 p.m., Thursday, Sept. 15, with all lanes and ramps reopening to traffic by 9 p.m., Sunday, Sept. 18. These closures will cause significant delays throughout the weekend. WSDOT is encouraging travelers to plan ahead, allow extra time for travel and reschedule discretionary travel if possible.

Lane reduction and ramp closure details

Over the four days of work, crews plan to excavate and replace the existing culvert underneath I-405 in three phases beginning at the southbound I-405 off-ramp to Exit 9 and moving east toward the northbound I-405 on-ramp. The phased work schedule is:

  • 11 p.m. Thursday, Sept. 15, to 5 p.m. Friday, Sept. 16: the southbound I-405 off-ramp to Exit 9 will be closed. Southbound I-405 will be reduced to two lanes between Coal Creek Parkway Southeast and Exit 9. Drivers wishing to exit southbound I-405 will detour to the Northeast 44th Street (Exit 7) off-ramp.
  • 11 p.m. Friday, Sept. 16 to 10 p.m. Saturday, Sept. 17: all lanes of I-405 at Exit 9 will be closed. Drivers will use the Exit 9 ramps as the detour with flaggers directing traffic.
  • 11 p.m. Saturday, Sept. 17 to 9 p.m. on Sunday, Sept. 18: the Exit 9 on-ramp to northbound I-405 will be closed. All other lanes and ramps will be open.

Detour routes available for full interstate closure

Signed detour routes will be in place for the 23-hour full interstate closure. From 11 p.m. Friday, Sept. 16, to 10 p.m. Saturday, Sept. 17, travelers will use the Exit 9 ramps as the detour with flaggers directing traffic. Travelers should expect heavier-than-normal traffic along those routes during the closures.

To help avoid congestion and keep traffic flowing travelers can:

  • Allow extra time for travel.
  • Take alternate routes.
  • Consider taking public transportation or carpooling.
  • If possible, reschedule discretionary trips.
  • Travel early in the morning or late in the evening when traffic volumes tend to be lower.

For additional information about these closures, read our recent blog post.

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