Diverging diamond interchange, two new lanes for I-90/SR 18 exchange in Snoqualmie
Sep 10, 2024, 6:19 AM
An overhead photo of the new ramps that will shift to for the SR 18/Snoqualmie Parkway to westbound I-90. (Photo courtesy of Aecon)
(Photo courtesy of Aecon)
Drivers are getting their first taste of the new diverging diamond interchange at Interstate 90 (I-90) and State Route 18 (SR 18) this week as new ramps open up.
Commuters from Snoqualmie are driving on the new ramp to westbound I-90 this morning. It opened overnight. The new off-ramp from eastbound 90 to Highway 18 will open Friday morning.
These are the first portions of the new diverging diamond to open to drivers, and today’s changes will be noticeable.
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“The turn off onto the new ramp will be a couple 100 feet up the highway, closer to Snoqualmie,” Washington Department of Transportation’s (WSDOT) Communications Consultant David Rasbach said.
Be sure to follow the signs and take your time as you use the ramp the first few times. This is a busy week for construction on the project, with nightly lane closures.
“People traveling in the area should expect various nighttime ramp and lane closures near the I-90/SR-18 interchange and plan for detours and or delays,” Rasbach said.
In addition to opening the new ramps, contractors are installing new signs.
“We’re also lifting three over-head sign bridges, which are structures that hold signs that will direct people through the new diverging diamond once the interchange opens,” Rasbach added.
The diverging diamond is expected to open in early 2025, but that’s not the only work going on along the corridor. The two-and-a-half-mile widening of Highway 18 continues to make progress. Workers just poured the deck on the new Raging River Bridge.
“We’re waiting for that to cure, and then we’re going to continue building that out,” Rasbach said. “A little bit further south at Deep Creek, we’re building the columns that will support the new bridge there. We hope to lift the girders onto that bridge and start forming that out later this fall.”
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The widening project should be finished in the middle of next year. The entire project, including all the off-freeway work, should wrap up in late 2025.
WSDOT will then begin the widening of Highway 18 south to the Issaquah-Hobart Road.
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