I-405 lane reductions in Bellevue Sept. 15-18 for emergency repair work

By Victoria Miller

Drivers on Interstate 405 should prepare for four full days of emergency repair work that will include a 23-hour full closure of the highway and lane reductions in the Bellevue area near 112th Avenue Southeast/Lake Washington Boulevard Southeast (Exit 9) from Thursday, Sept. 15 to Sunday, Sept. 18. During that time, crews will excavate and replace an existing culvert with an interim drainage structure. At least one lane or ramp will be open at all times during the four-day closure.

Why is this work happening?

In spring 2022, we discovered a failed culvert under mainline I-405 in the vicinity of 112th Avenue Southeast near the Newport Hills Park and Ride in Bellevue. The failed culvert resulted in an approximately 15-foot-deep sinkhole in the Newport Hills Park and Ride and has the potential to cause similar sinkholes under mainline I-405. This emergency repair of the culvert should prevent that from happening.

A failed culvert led to a large sinkhole forming in a Bellevue Park and Ride, leading to emergency repairs in mid-September.

How will the construction be phased?

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.

• Phase One
  From 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 and Exit 9. Drivers wishing to exit southbound I-405 will detour to the Northeast 44th Street (Exit 7) off-ramp.
• Phase Two
  From 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.
• Phase Three
  From 11 p.m. Saturday, Sept. 17 to 9 p.m. Sunday, Sept. 18, the Exit 9 on-ramp to northbound I-405 will be closed. All other lanes and ramps will be open.

The repair work will be divided into three phases and drivers should expect at least one lane or ramp to be open on I-405 at all times during the four-day project.

During the second phase of work when all lanes of I-405 are closed, we will have flaggers directing traffic from the off-ramp over the city street and back onto the highway via the on-ramp at the same exit.

The southbound I-405 offramp to Exit 9 will be closed during the first 18 hours of the closure. Drivers will use the southbound offramp at Northeast 44th Street (Exit 7) as the detour.

How you can help

We realize how big of a challenge/inconvenience this is for drivers. There will also be other events occurring over the course of these four days, including concerts in Seattle and Woodinville, and the Washington State Fair at the Puyallup Fairgrounds.

During the second phase of work, from 11 p.m. Friday, Sept. 16 to 10 p.m. Saturday, Sept. 17, all lanes of I-405 will be closed. Drivers will use the Exit 9 ramps as the detour with flaggers directing traffic.

With all this happening at once, we ask that drivers please do their best to be patient, give each other space, stay alert for road workers, and if you can delay your trips until very early or very late, do so. It will be a huge team effort to safely help this emergency repair project get done, and we want you on our team.

To stay up to date with the latest traffic and closure information, "know before you go" by using our real-time travel map. If you have questions about this emergency work and closure, you can contact our project office at i405sr167program@wsdot.wa.gov.