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I-90 Snowshed Removal

The snowshed took only two days to remove. Take a look at the timelapse video .

A look back

Snowshed construction in 1950

The snowshed during construction in 1950

After 64 years of protecting the westbound lanes from avalanches on I-90 east of Snoqualmie Pass, the snowshed is coming down. Two large bridges will replace the snowshed and construction starts this summer.

In the early 1900's, a 419-foot long wooden snowshed was used for many years along Keechelus Lake to protect the highway from avalanches. The Milwaukee Railroad also built two wooden snowsheds on what is now the John Pioneer Trail and part of the Iron Horse State Park. In 1950, the wooden snowshed was removed and replaced with a new snowshed made from concrete. It only took about nine months to build due to a building technique known as precast construction, which is still used today.

The purpose

Snowshed construction in 1950

The snowshed during construction in 1950

Since the late 1800's, snowsheds have been used as an efficient and low-cost way to protect the world’s highways and railways from avalanches and other falling debris. The snowshed on Snoqualmie Pass is located below several avalanche chutes. For the past 64 years the snowshed has provided a good solution for keeping Snoqualmie Pass open to drivers during the winter months. However, the snowshed no longer meets the needs for a modern transportation facility.

The future

This summer the snowshed will be removed and replaced with avalanche bridges as part of the $551 million project to widen I-90 from Hyak to the Keechelus Dam. The elevated structures will allow snow to slide under the bridge between the bridge piers, which will reduce closures in the winter for avalanche control work.

Did you know

  • The snowshed is 500 feet long and 34 feet wide 
  • It cost $342,000 to build in 1950
  • In 1995, the snowshed was listed on the National Register of Historic Places
  • The snowshed has a concrete roof supported by a 30-foot-tall, 15-inch-thick retaining wall that hugs the hillside
  • The snowshed's roof consists of 200 precast concrete T-beams