I-90 - Eastgate to SR 900 - Corridor Improvements

Project news

  • Work continues in both directions of I-90. Plan ahead and use caution.
  • Sign up to receive email updates about this project and other east King County topics.
  • Check out the Flickr album with project photos


Through fall 2021, WSDOT contractor crews will add capacity on both directions of I-90 between the Eastgate and West Lake Sammamish Parkway interchanges, by restriping the existing roadway and creating auxiliary lanes. Crews will also build sound walls in strategic locations within the project area to minimize traffic noise.

What's an auxiliary lane?
An auxiliary lane is a supplemental or extra lane that’s added between closely spaced interchanges. They are frequently used to give drivers more time to safely enter or exit the highway, depending on if they need to merge over, speed up or slow down. These new lanes will be located on the outside of the existing lanes in both directions of I-90, adding capacity and accessibility to all travelers 24 hours a day, seven days a week.

Auxiliary lane diagram for the I-90 Eastgate to SR 900 Corridor Improvements project.

Work details

Travelers should plan ahead for the following throughout this two-year project:

  • Overnight lane and ramp closures between the hours of 8 p.m. and 5 a.m.
  • Single lane closures during daytime hours.
  • Around-the-clock shoulder closures.
  • Narrowed and shifted lanes on both directions of I-90.

Temporary I-90 traffic changes
Before the new auxiliary lanes can be added, contractor crews have to reinforce catch basins, drainage pipes and utility covers along the shoulders so they can withstand the weight of everyday traffic. To safely perform this work, crews have temporarily restriped both directions of I-90, shifting traffic so this work can be completed.

Temporary NW Sammamish Road traffic changes
NW Sammamish Road is reduced to one lane.

  • Westbound lane will be open for one-way local access only.  
  • Eastbound lane will be closed.
    • Traffic will be routed from West Lake Sammamish Parkway to Lakemont Blvd, Newport Way and State Route 900, before reentering westbound NW Sammamish Rd.


  • 2016 - 2019: Design phase.
  • March 2019: Project was advertised for competitive bidding.
  • May 2019: Project was awarded to Atkinson Construction, LLC.
  • August 2019: Construction began.
  • Fall 2021: Construction is scheduled to be complete.


Financial Data for PIN 109052P
Funding Source Amount ($ in thousands)
2003 Gas Tax (Nickel Funding) $0
2005 Gas Tax (TPA) $0
Pre-Existing Funds (PEF) $0
CWA $73,035
Total $73,035


Tom Pearce
WSDOT communications


Map for the I-90 Eastgate to SR 900 Corridor Improvements project.