Progress being made on widening State Route 18
Aug 24, 2023, 5:02 AM | Updated: 8:00 am

An old photo of crews are widening the north side of SR 18 to make room for the new flyover ramps back in 2011. (Photo from Flickr @WSDOT )
(Photo from Flickr @WSDOT )
Since ramping up work earlier this year, the widening project of State Route 18 and the construction of the new diverging diamond interchange at Interstate 90 are making some good progress.
Earlier this week, the contractor finished building half of the new just west of I-90. Traffic was shifted onto it so workers could start building the other half.
More Chokepoints: Ambitious fish passage work to impact I-90 for next few years
The Washington State Department of Transportation (WSDOT) Spokesperson Adrienne Hatmaker said this is the first of three bridges that need to be built for the widening.
“We do have the other two bridges that we’re beginning clearing and doing some grubbing in the Raging River area,” Hatmaker said. “Heading out to the Deep Creek area, we’re doing some more clearing on the east side of that bridge. People are going to see more trees being cleared, and that’s in preparation for next summer’s in-water work.”
And while the workers are racing the incoming fall weather, project manager James Harper said the weather will not stop construction.
“There’s enough work to keep us busy over the over the winter,” Harper said. “The plan is to finish this by early 2025.”
The next do-to item is to start building a new fish passage that will go under the new interchange, and that leads us to this weekend’s closure.
“The ramp closure we have coming up is SR 18 or Snoqualmie Parkway to eastbound I-90,” Hatmaker said. “We are installing a culvert under the ramp, and this is all connected to the drainage system with the interchange.”
Starting at 9 p.m. Friday, the eastbound on-ramp from SR 18 to I-90 will be closed until early Monday morning. It’s not a huge closure, but that spot gets very busy, especially on weekends.
Harper said the project will build a series of fish habitats to improve access throughout the area.
“It’ll be a new fish passable culvert that will go underneath the eastbound on-ramp,” he said. “This will eventually connect up with the rest of a new fish passable channel that will allow for fish passage through the interchange.”
“While keeping the public informed about the upcoming closures and the progress being made, I do want to highlight what we have seen on this corridor this week.” Harper continued. “There have been two very serious crashes on 18 through the construction zone this week. Both have closed the highway during the morning commute. It’s a good reminder that there are a lot of distractions on that route and that the speed limit has been reduced.”
Hatmaker said drivers need to pay close attention to keep everyone safe.
“Lowering the speed limit is as much as we can do,” she said. “It’s really up to drivers to obey those laws and consider their fellow commuters as they’re passing through there.”
The from I-90 to the Tiger Mountain Summit is scheduled to finish in 2025. Then, the work will begin to widen SR 18 the rest of the way to the Issaquah-Hobart Road.
Check out more of Chris’ Chokepoints.