Interstate 90 in eastern Washington State is a critical transportation corridor connecting the large population and business centers of the Puget Sound with the agricultural industries and recreational activities of the area.
 

I-90 travelers have been experiencing increased congestion, delays due to avalanche closures, rough pavement conditions, rockslide activity and potential wildlife collisions on the highway. 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. Washington State Department of Transportation (WSDOT) is expanding a 15-mile stretch of I-90 from Hyak to Easton to meet both the current and future needs of this transportation corridor.

A Rich History

Long before the early explorers came to the Northwest, Native Americans on both sides of the mountains carved foot trails across the Central Cascades, including Snoqualmie Pass, to hunt deer, elk and other game animals, fish for salmon, and gather berries. They also traveled to this area to gather wild plants for food, medicinal purposes, and basket weaving. Pacific Northwest tribes like the Snoqualmie Indian Tribe and Yakama Nation, used foot and horse trails across the Central Cascade Mountains for trading, as it had the lowest pass elevation in the territory. 

In 1865, construction started on a wagon road on the west side of the pass to lure settlers to Seattle. By 1905, the road had to be rebuilt several times to remain passable. The first automobile drove over the Snoqualmie Pass that same year. A two-lane road was built in 1915.

In the 1950's and 1960's, state highways were renumbered to meet the American Interstate Highway System, creating Interstate 90 from U.S. Route 10. In the 1970's, major highway projects near the pass were completed that replaced concrete pavement, straightened roadway curves, and made other safety improvements. The efforts in the 1970's kept traffic moving across Snoqualmie Pass for the next 30 years. 

On an average day, 28,000 vehicles travel over Snoqualmie Pass and it doubles on weekends and holidays. Traffic volumes are expected to increase 2.1 percent every year, reaching an average of over 41,000 vehicles per day by 2030. 

Long-Term Solution

WSDOT is working with the United States Forest Service (USFS), the United States Bureau of Reclamation (USBR), Federal Highway Administration (FHWA), United States Fish and Wildlife Service (USFWS), Washington Department of Fish and Wildlife (WDFW), Department of Ecology, Environmental Protection Agency, cities, counties, and community groups to develop a long-term vision for the I-90 corridor between Hyak and Easton. This effort culminated in a draft Environmental Impact Statement (EIS) that outlines improvements needed to meet projected traffic demands, improve public safety, and meet identified project needs along the 15 miles of I-90. The Final EIS was published in 2008.

Travelers will experience a safer, more efficient six-lane freeway, minimized closures as a result of avalanches and rock slides, and a smoother ride due to new pavement designed to last 50 years when all improvements are completed. Wildlife habitat on either side of I-90 will be reconnected with the installation of new bridges and culverts, protecting both wildlife and the traveling public. 

Separated into Two Phases

Phase 1 of the I-90 project covers the first 5 miles of the 15-mile corridor from Hyak to Keechelus Dam. The 2005 gas tax provided $551 million to widen I-90, build and replace bridges including two new avalanche bridges, stabilize rock slopes, and expand chain-up and chain-off areas. Construction started in 2009. The first 3 miles was completed in 2013 and the remaining 2 miles are scheduled to be complete in 2018.
 
 Phase 2 of the project covers the next 2 miles of the corridor from Keechelus Dam to the Stampede Pass interchange. Project savings from Phase 1 provided $108 million to widen I-90, build and replace bridges, stabilize rock slopes and build the first wildlife overcrossing in the project corridor. Construction started in 2015 and is scheduled to be complete in 2019.

WSDOT will increase capacity and improve safety on I-90 by: 

·       Adding a new lane in each direction

·       Replacing deteriorating concrete pavement

·       Reducing road closures due to avalanches

·       Adding and replacing bridges and culverts

·       Straightening sharp curves

·       Stabilizing rock slopes

Project benefits include:

·       Increased Safety:Corrective measures will reduce the risk of avalanche and associated road closures within the project area as well as reduce the risk of rock and debris slides from unstable slopes onto the roadway.

·       Congestion Relief: WSDOT will increase capacity by 50 percent in each direction to accommodate projected traffic volumes for the next 20 years. Crews will extend chain-up-and-off areas assisting freight vehicles.

·       Environmental Projection: WSDOT will reduce the risk of collisions between wildlife and vehicles by building wildlife crossings.

Future Construction

In 2015, the Legislature secured $426 million with the Connecting Washington funding package to complete the remaining 8 miles of the corridor from the Stampede Pass interchange to Easton. The remaining 8 miles of the project are divided into three phases and widens I-90 from four to six lanes, straightens curves, adds and replaces bridges and culverts, addresses wildlife connectivity and expands chain-up areas.

 Photos courtesy of Washington State Department of Transportation