Mountains to Sound Greenway, IATC, and Partners Send Joint Letter on SR 18 Widening

A joint letter in support of the SR 18 widening project was sent to Mark Allison, Project Engineer with WSDOT. Our organizations encourage WSDOT to include wildlife habitat connectivity and recreation connections as goals of this important infrastructure project.

 September 19, 2019

Mark Allison, Project Engineer

Washington State Department of Transportation

15700 Dayton Ave. North

Seattle, WA 98133

Re: A Future Vision for State Route 18 between Snoqualmie and Maple Valley: WSDOT I-90/SR 18 Interchange Improvements projects

Dear Mark and members of the project team:

Thanks to the Washington State Department of Transportation (WSDOT) for seeking input to inform the I-90/SR 18 Interchange reconstruction projects. On behalf of our organizations signing on below, please accept our thanks for these important infrastructure improvements.

Collectively, we have invested significant resources and more than two decades of advocacy to preserve the forested character of this rural interchange, just south of the city of Snoqualmie. Instead of mini malls and gas stations, we have a forested gateway to the Cascades. Now, it is time to ensure active transportation access and wildlife connectivity in this special place.

Designing dedicated shared use paths and crossings as part of the planned diverging diamond interchange will help pedestrians and bicyclists move safely through the interchange. Once this is built, a shared use path will connect with planned regional trails to Maple Valley along SR 18, to Snoqualmie Ridge along the Parkway, to Preston along a future extension of the Mountains to Sound Greenway Trail, and as a potential future route for the nation-wide Great American Rail-Trail, in addition to preserving the scenic character of the I-90/SR-18 interchange.

We will continue to support preservation of scenic character, wildlife habitat, and improved regional trail connections as planning for the interchange moves into its next phase.

Safe connections for wildlife

The Tiger Mountain and Raging River state forests are held in trust to benefit K-12 schools, counties, and junior taxing districts. Further, these vital working forests provide significant wildlife habitat and world class recreation. Improvements to SR 18 should connect these state forest trust lands and protect wildlife habitat in the Raging River basin.

We encourage WSDOT to make connectivity of wildlife habitat a key goal of SR 18 widening design. This phase of SR 18 widening – and future plans for widening all the way south to Maple Valley – should include safe passage for wildlife at river crossings and in key wildlife corridors. The Interstate 90 Snoqualmie Pass East project provides excellent examples of under- and over-crossings for wildlife that aid animal migrations and reduce the risk of collisions.

Safe connections for people

The SR 18 corridor also presents outstanding opportunities for expanding the regional trail network with connections from Snoqualmie south to Maple Valley and west to Preston, and with access to the wildland trails in the East Tiger and Raging River trail systems.

The new infrastructure being planned at the SR 18 interchange does include crossings for bicyclists and pedestrians. We would like to ensure that the design also includes connections for active transportation heading south. As we plan for SR 18 widening, now is the time to ensure that transportation infrastructure also allows for multi-use access beyond the interchange for bicyclists, pedestrians, recreation-seekers and commuters. Any new highway bridges, culverts, and other highway crossing infrastructure needed along SR 18, including over the Raging River and Deep Creek, should be built wide enough to accommodate a regional trail to improve safety, mobility, and access.

Ensuring seamless active transportation options will ensure that everyone has access to these places.

Bridges over Deep Creek and the Raging River: a once-in-a-generation opportunity

Widening the west end of both the planned highway bridge spanning the Raging River and the highway structure planned for Deep Creek will ensure future active transportation regional trail connections envisioned in King County’s Regional Trail Plan, while serving the dual purpose of connecting between wildland trail systems on each side of the highway. Designing and engineering SR 18 highway infrastructure for active transportation must happen during this phase of the project, so that a pedestrian and bike path can be constructed during the same timeframe as the SR 18 highway widening project. This important community benefit was identified as a high priority during WSDOT’s project outreach and will serve to reduce traffic in the project area by reducing vehicle trips for commuters and residents in the Snoqualmie Valley connecting to recreation trail system assets.

We encourage you to seek additional state funding to complete these projects as needed.

We very much appreciate the Washington State Department of Transportation tackling these complicated and important infrastructure projects that are of vital importance to our region and the state of Washington.


Amy Brockhaus, Deputy Director, Mountains to Sound Greenway Trust

Brock Milliern, Division Manager – Conservation, Recreation and Transactions

Washington State Department of Natural Resources

Katy Terry, Acting Parks Director, King County Parks

Claire Martini, Policy Manager, Cascade Bicycle Club

Alex Alston, State Policy Director, Washington Bikes

Lindsay Frickle, Executive Director, Issaquah Alps Trails Club

Andrea Imler, Advocacy Director, Washington Trails Association

Yvonne Kraus, Executive Director, Evergreen Mountain Bike Alliance

cc: Senator Mark Mullet

Representative Bill Ramos

Representative Lisa Callan

Washington State Secretary of Transportation Roger Millar

Mike Cotten, Regional Administrator, Washington State Department of Transportation

Barb Chamberlain, Director, Active Transportation Division

Justin Nawrocki, Active Transportation Coordinator, Washington State Department of Transportation

Mayor Matt Larson, City of Snoqualmie

IATC Staff