State Route 9 Corridor Program

News

• Between 2005 and 2013, we expect to invest $325 million to improve SR 9 through Snohomish County.

• For more information, take a look at the SR 9 corridor project folio (pdf 2.3 mb) and the SR 9 Safety Study (pdf 1mb).

• Sign up for weekly e-mail updates on our construction projects in Snohomish County.

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State Route 9 extends from SR 522 north of Bothell to the Canadian border at Sumas, spanning a distance of 98 miles. The highway parallels Interstate 5 to the east as it skirts through Snohomish, Skagit, and Whatcom counties.

Growing population, increasing congestion
Due to regional economic development and the demand for affordable housing, the population of Snohomish County increased by nearly 80 percent between 1980 and 2000. 

This population growth has caused an influx of traffic on SR 9 throughout Snohomish County. The once rural road is now a critical corridor for both commercial vehicles and commuters. Current traffic volumes have exceeded the capacity of the two-lane roadway, making the once free-flowing, rural SR 9 a congested highway during peak travel times.

Increased congestion is not the only concern for SR 9: heavy traffic has also resulted in an increase in the number of rear-end, sideswipe, and head-on collisions throughout the corridor. From 1993 to 2000, there were an average of 325 collisions per year on the SR 9 corridor through Snohomish County. By 2007, that average had increased to almost 450 collisions per year, totaling nearly 4,000 collisions between 2000 and 2007.

The end result: Improving safety and reducing congestion
Between 2005 and 2013 WSDOT will invest $325 million to transform SR 9 from a rural road into a wider, safer highway. To improve safety and reduce congestion on SR 9, we will widen the highway to four lanes in some areas, add turn lanes at key intersections to reduce the risk of head-on and sideswipe collisions, install divided medians at select locations to prevent crossover collisions, and upgrade pavement markings, guardrail, drainage, culverts and lighting where needed.

We began construction on SR 9 in summer 2005 and will wrap up by 2013. These improvements will help relieve congestion, improve traffic flow, and enhance safety throughout the SR 9 corridor.

Current SR 9 improvement projects underway include: