SR 9 - 108th St NE - Intersection Improvements

Project News

  • Construction will resume late summer 2019.
  • This project will require two full weekend closures of the intersection of 108th Street Northeast and State Route 9.
  • Construction updates are located on the Snohomish County construction page.
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Contractor crews with Granite Construction will install a single lane roundabout on State Route 9 at 108th Street Northeast in Marysville to reduce wait times and collisions at the intersection. This project has been combined with a nearby paving project on SR 92 that will fill existing potholes and cracks from 147th Avenue Northeast to Quarry Road.

Why is WSDOT installing a roundabout on SR 9 at 108th Street Northeast?
About 16,000 drivers use this intersection every day. Up to 1,500 of them are trying to turn from the stop signs at 108th onto SR 9. Trying to turn from a dead stop onto a highway increases the risk of collisions, including rear-end crashes, the most common type at this intersection.

  • From 2012 to November 2017, 51 drivers were hurt in 28 collisions at SR 9 and 108th Street Northeast.
  • Ten collisions were rear-end crashes.
  • At least six of those collisions happened at the stop signs on 108th.

A roundabout greatly reduces the need to stop to make left turns, allowing traffic to move freely. The change is needed quickly. The Puget Sound Regional Council forecasts the number of average daily travelers on this stretch of SR 9 will increase to 17,000 in two years, and nearly 19,000 in 2030. Community Transit’s 2030 long-range plan (pdf 4 mb) also identified this corridor as a route needing more commuter bus service for the growing population.

Detours and closures
One weekend-long closure of 108th Street Northeast between 87th Avenue Northeast and SR 9 is required to reduce the height of a hill currently blocking drivers' view of the eastbound entrance into the roundabout. Posted signs will route drivers along a 4-mile detour. Work on the roundabout itself will require an additional weekend closure of the intersection at SR 9 and 87th Avenue Northeast. During that closure, posted signs will route drivers along an 8.3-mile detour. In addition to those full closures, there will be 40 nighttime single-lane closures during which flaggers will aid drivers.

View project detours

The End Result

Building a roundabout at SR 9 will alleviate wait times, and may also reduce the risk of collision.

  • The Insurance Institute for Highway Safety (IIHS) and Federal Highway Administration (FHWA) studies on roundabouts show they typically reduce injury crashes by 37 percent.
  • The IIHS and FHA also found a 90 percent reduction in fatalities at intersections with roundabouts compared to intersections with no improvements.

Get more information on the benefits by visiting our roundabout page.

Needs & benefits

  • Safety: A roundabout will reduce the risk of rear-end collisions.
  • Congestion: The improvement will help the flow of traffic and reduce the length of current backups.
  • Environmental: Shrinking delay times reduces idling, which may help air quality.


Summer 2019: Construction scheduled to start.
Fall 2019: Construction scheduled to be completed.


Financial Data for PIN 100924C
Funding Source Amount ($ in thousands)
2003 Gas Tax (Nickel Funding) $0
2005 Gas Tax (TPA) $0
Pre-Existing Funds (PEF) $3,481
CWA $0
Total $3,481


Frances Fedoriska
WSDOT Communications
Phone: 206-440-4690

In 2018, contract crews will install a single-lane roundabout at SR 9 and 108th Street Northeast.

SR 9 at 108th Street Northeast
The west side of the intersection on 108th Street Northeast at SR 9 is about 4 feet too high. This is the hill drivers currently drive over to get to the intersection. During a weekend closure, this hill will be reduced to give drivers a better view of the roundabout they will be entering.