I-90 Snqoaulamie Pass East - Engineering Innovation

Interstate 90 is a critical link connecting Puget Sound's large population and business centers with eastern Washington, the heart of the state's agricultural and viticulture industries. The uninterrupted movement of people, freight and business over Snoqualmie Pass is essential to the quality of life, and the economic vitality of Washington state.
Snoqualmie Pass is one of three major cross-mountain passes and is crucial as freight corridor and part of the resilient transportation network for the state. The purpose of the I-90 Snoqualmie Pass East project is to meet the projected traffic demands, improve public safety, and meet the identified project needs for a 15-mile stretch of I-90 from Hyak to Easton that runs through the Okanogan-Wenatchee National Forest. These needs include addressing road closures due to avalanches and slope instability, replacing structural deficient pavement, providing additional capacity for increasing traffic volumes, and addressing ecological connectivity.
The Washington State Department of Transportation took an innovative approach to project delivery. WSDOT was innovative in collaboration with the community and resource agencies in preparing the environmental documentation and addressing ecological connectivity - enhancing wildlife movement through corridor - as part of a context sensitive solution for that project.
As part of the National Environmental Policy Act, WSDOT created an Interdisciplinary Team as an advisory group to recommend a Preferred Alternative to incorporate concerns from agency stakeholders. What WSDOT did differently was to populate its team with members from other agencies. This ensured these agencies' needs were met as a Preferred Alternative was recommended to WSDOT decision makers.
To address ecological connectivity WSDOT worked with biologists to identify and construct wildlife connectivity structures that connected habitat as well as provide a safe passage for wildlife to move under or over the interstate, while providing a safety benefit for drivers by reducing collisions with wildlife.