SR 9 - SR 204 Intersection Improvements - Design options

The design options below are representative of a collaborative effort between the project team, the Lake Stevens community and a Stakeholder Advisory Group (SAG) to find a new design option for the SR 9/SR 204 intersection that meets the needs of a growing region. The collaborative process began in August 2016 with identifying goals that could be achieved with a new intersection design. Design concepts were developed and evaluated together with the SAG and through traffic analysis to make sure they could potentially meet the goals set by the project team and SAG. After evaluating many different intersection design concepts, SAG members recommended the grade-separated alternative, Concept E2b-v4, as the preferred alternative in August 2017. However, during the design phase, the project team conducted surveying that included looking at underground subsurface conditions and groundwater levels. The groundwater level turned out to be just nine feet below the surface. This meant that the cost, materials, and overall feasibility of the preferred alternative needed further review.

Current Preferred Alternative

 Re-evaluating the design in fall 2018 allowed for further innovation and cost savings through practical design – all while staying true to the project’s purpose, need and traffic performance. The team reviewed a widening and roundabout at-grade design. The roundabout design provided more overall benefits than the widening option and performed as well as the original (E2B-V4), which called for a grade separation, without the added time and expense brought on with the groundwater issues.

Continuing with the project’s strong tradition of public input and engagement, the SAG members asked for further review of the roundabout design, which WSDOT did in early 2019 in the form of a business forum in January and a public open house in March. The SAG met in April to discuss feedback from the public and was supportive of the roundabout design overall, but wanted to see the design further refined. The group met on June 19, 2019 and reached a consensus to move forward with the roundabout design as the new preferred alternative.

Roundabout Design

This design concept includes roundabouts at four locations: SR 9/SR 204 intersection, SR 9/ North Davies Road (new intersection), Vernon Road/ North Davies Road (relocated roundabout), and 91st Avenue Northeast/ Vernon Road. This design diffuses traffic from the SR 9/SR 204 intersection by providing more routing options. This design also allows for direct entrance and exit from Frontier Village onto SR 9 and SR 204.

This design concept includes roundabouts at four locations: SR 9/SR 204 intersection, SR 9/ North Davies Road (new intersection), Vernon Road/ North Davies Road (relocated roundabout), and 91st Avenue Northeast/ Vernon Road.

Previously Evaluated Design Options

The below list of concepts was developed as refinements during the second quarter of 2017. These refinements were key to reaching consensus on the original preferred alternative design option E2B-v4.

Tight Diamond Interchange with Market Place Improvements (Concept E2b-v4)
This design concept, referred to as E2B-v4, was the original SAG-recommended preferred alternative. It was developed as a refinement of the previously developed design concept E2B. Four variations were developed as refinements of E2B. Variation E2B-v4 explored opening the Vernon Road cul-de-sac proposed in Concept E and keeps the current Vernon Road configuration. 
Graphic: Concept E2B-v4

Tight Diamond Interchange (Concept E2A)
This design concept is identical to Concept E, however refined for a two-lane SR 9 each way. A traffic analysis of the original Concept E showed no need or significant benefit for an added lane along SR 9.
Graphic: Concept E2A

Tight Diamond Interchange with Market Place Improvements (Concept E2B)
This design concept consists of a tight diamond interchange with a two-lane SR 9 (Concept E2A) and adding a through lane at the Market Place and SR 9 intersection in each direction.
Graphic: Concept E2B

Tight Diamond Interchange with Davies Half Interchange/Overpass (Concept E2C)
This design concept consists of tight diamond interchange with a two-lane SR 9 and includes an above grade Vernon/Davies half interchange over SR 9.
Graphic: Concept E2C

Tight Diamond Interchange with Market Place Improvements and Davies Half Interchange/Overpass (Concept E2D)
This design concept consists of a tight diamond interchange with a two-lane SR 9 and includes both the SR 9/Market Place intersection improvements (through-lane at Market Place and SR 9) and the above grade Vernon/Davies half interchange over SR 9.
Graphic: Concept E2D

Initial Design Option Refinements

The below list of concepts was refined from early ideas developed during the fourth quarter of 2016.

Local connectivity improvements (Concept B)
This option made several improvements near the SR 9/SR 204 intersection, including a roundabout interchange at SR 9/SR 204 with SR 9 traveling under the roundabout to allow SR 9 traffic to flow straight through. 
Graphic: Concept B

This design improved access to Frontier Village via 7th Street Northeast by adding a cul-de-sac at Vernon Road, closing off 92nd Avenue Northeast, and creating an opportunity to turn right off northbound SR 9 to 4th Street Northeast and turn right from 4th Street onto north SR 9.  
Graphic: Concept C

Recessed ramp (Concept G2B)
This concept created a direct connection from eastbound SR 204 to northbound SR 9 by constructing a ramp under SR 9 that begins on SR 204 west of 91st Avenue Northeast and continued along SR 204, re-emerging onto northbound SR 9. 
Graphic: Concept G2B

Tight diamond interchange (Concept E)
This design concept lowered SR 9 below the interchange and added a lane to SR 9 in both directions from south of Market Place to the interchange and north to Lundeen Parkway. The SR 9/SR 204 intersection stayed at grade with four lanes of SR 9 (two lanes each way) under the intersection. Created on- and off-ramps in both directions of SR 9 and updated the Vernon Road off-ramp.
Graphic: Concept E

Roundabout interchange (Concept H)
This design concept is similar to the tight diamond interchange (Concept E), but it didn't add new lanes to SR 9. The SR 9/SR 204 intersection would be changed to an at-grade roundabout interchange with SR 9 traveling below the roundabout. This concept allows SR 9 traffic to flow through the interchange. On- and off-ramps were added in both directions of SR 9.
Graphic: Concept H