Roads Designated as Ultimate Capacity

The county currently has three arterial units at ultimate capacity:

35th Avenue Southeast from SR 524 to Seattle Hill Road (Arterial Units #204, #207/336, and #337/420)

On July 13, 2022, the county council unanimously adopted Motion 22-259 designating 35th Avenue Southeast from SR 524 to Seattle Hill Road (Arterial Units #204, #207/336, and #337/420) as ultimate capacity. The county has invested nearly $33M in state and federal grants, developer mitigation fees, and local tax dollars to widen these arterial units to three lanes and construct them to full urban standards including curbs, sidewalks, and bicycle lanes and the county council determined that excessive expenditure of public funds would be required to provide additional capacity on these arterial units through any further widening and such excessive expenditure is not warranted.  To maintain mobility and preserve the capacity in this corridor, Snohomish County Public Works will implement travel demand management (TDM) measures, explore innovative non-transit options with Community Transit and support adding the 35th Avenue SE corridor into its service area, continue to implement county access standards as remaining development occurs, collaborate with WSDOT and other cities to coordinate signal timing, and pursue possible additional system improvements on parallel routes such as 43rd Avenue SE and 51st Avenue SE per the county’s comprehensive plan.

164th Street Southwest/Southeast (Arterial Units #218 and #219)

On December 17, 2007 the county council unanimously adopted Amended Motion 07-123 designating 164th Street Southwest/Southeast (Arterial Units #218 and #219) as ultimate capacity. To maintain mobility and preserve capacity in this corridor, Snohomish County Public Works will implement a congestion management strategy including TSM, TDM, and access management. This site will be updated as that strategy is further developed and implemented.

Snohomish-Woodinville Road (King Co. Line to SR 522 EB Ramps)

Snohomish County Council Motion No. 97- 202 designated Snohomish-Woodinville Road as being at ultimate capacity effective June 23, 1997. The motion laid out in detail why this action was taken and what it means for developers and the county. In the motion the council directed DPW to improve Snohomish-Woodinville road’s operating efficiency (e.g., shoulders and/or center turn lane). In March 2000 a pre design study to evaluate design alternatives was completed. The study confirmed that the lack of width between the railroad tracks and SR 522 at the county line precludes the possibility of constructing additional general-purpose lanes. The final improvements on Sno-Wood Road were completed in 2005. The improvements include two travel lanes, a center turn lane, bicycle lanes in both directions, a planter strip, curb, and sidewalk on the west side, storm water detention ponds, and a traffic signal at the intersection with 240th Street Southeast. As the road approaches the SR 522 off-ramp, it widens to five lanes. This configuration matches the WSDOT proposed improvement on SR 522. The improvements were coordinated with the City of Woodinville at the south end of the project and the development of a large Costco store at the intersection with 240th Street Southeast. Costco constructed some of the improvements as offsets to their traffic mitigation fees.