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Project overview
Snohomish County keeps growing and traffic grows with it. State Route 9 was once a rural, two-lane highway. Today, it serves as a key north-south alternative to I-5 for commuters and freight moving through Snohomish County. Peak travel times now bring regular congestion.
WSDOT developed a phased improvement plan that starts where congestion hits hardest. The goal is simple: cut backups and improve access to the city of Snohomish.
The plan includes:
- Building a new bridge west of the existing Snohomish River bridge to carry southbound SR 9 traffic.
- Building a new overflow bridge south of the SR 9 Snohomish River bridges.
- Rebuilding the southbound SR 9 on-ramp from Second Street.
- Adding an exit-only lane on northbound SR 9 to Second Street.
- Widening SR 9 between Marsh Road and Second Street near Snohomish.
- Making ADA improvements at the SR 9 and Marsh Road intersection.
- Restoring and repainting the existing SR 9 Snohomish River Bridge.
What to expect
In January 2026 crews began driving piles that will underpin the foundations for the new southbound bridges for SR 9. Pile driving will cause considerable, unavoidable noise near the work zone.
Construction on the widening of SR 9 is expected to begin in Spring 2026. This project may require the following closures at various points during construction:
- Nightly full or one-directional closures of ramps and mainline SR 9.
- Short (up to 2-weeks) and/or long term (up to 6-months) closures of Lowell-Snohomish River Road.
- Partial closures of Marsh Road and Airport Way.
Snohomish County’s population grew by more than 400,000 residents from 1980 to 2018 - and traffic increased proportionately on state highways across the region.
SR 9 was once a rural road with free-flow traffic. Today, the two-lane highway intended for locals has become a north-south alternative to I-5 through Snohomish County for commuters and freight traffic, leading to congestion during peak travel times.