I-90 - SR 18 Interchange Improvements - Snoqualmie Parkway/SR 18 Auxiliary Ramp - Complete August 2020

Project news

  • The new temporary SR 18/Snoqualmie Parkway auxiliary on-ramp to westbound I-90 is open to traffic. The final paving and striping occured in August 2020.


WSDOT contractor crews from Road Construction Northwest, Inc. used the old westbound I-90 weigh station property to create a second on-ramp lane for highway users. The traffic signal on SR 18 was also retimed, and ramp meters were added to evenly distribute vehicles merging onto westbound I-90.

These modifications are expected to provide some short-term congestion relief and help improve traffic flow on Snoqualmie Parkway, and nearby local intersections (such as SE 96th, 99th and Jocobia streets), before the new I-90/SR 18 interchange project is complete in 2023. 

Completed improvements 

Travelers will see the following changes: 

  • A right turn only lane on southbound Snoqualmie Parkway for drivers going to westbound I-90, with no traffic signal as they enter the ramp.
  • One westbound I-90 on-ramp lane for drivers coming from southbound Snoqualmie Parkway, and another on-ramp lane for drivers coming from eastbound SR 18.
  • A retimed traffic signal on SR 18, providing a longer green light for travelers turning on to westbound I-90.
  • Ramp meters for both westbound I-90 on-ramp lanes.

The new Snoqualmie Parkway/SR 18 auxiliary on-ramp to westbound I-90.
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Why meter the on-ramp?
The ramp meters will operate during peak commute times - activating automatically based on westbound I-90 traffic flow. Metering the two-lane on-ramp will reduce congestion on westbound I-90 by providing consistent gaps between vehicles, rather than allowing multiple vehicles to flood the highway at once.

Follow-up work 

An additional modification to the on-ramp will also occur before the new I-90/SR 18 interchange opens in 2023. 

Travelers should check the King County construction page or sign up for weekly email updates for current closure information. For more project photos, check the WSDOT Flickr page.


  • September 2019: Project was awarded to Road Construction Northwest, Inc. 
  • October 2019: Construction began.
  • Dec. 5, 2019: The new temporary auxiliary on-ramp opened to traffic.
  • Mid-December 2019 - Spring 2020: Project in winter suspension. 
  • Spring 2020: Final paving and striping is scheduled to occur. 
  • Summer 2020: Construction complete


This $1.03 million project was jointly funded by WSDOT and the city of Snoqualmie.