(Hyak, WA) It’s one of the biggest changes to come to Interstate 90 east of Snoqualmie Pass since it was expanded to a four-lane highway more than 40 years ago and it will save millions of dollars: The snowshed is coming down and bridges are going up.
When two, three-lane bridges – instead of a new snowshed – replace the 62-year-old snowshed now protecting only the westbound lanes, the result will be savings of about $650,000 a year, or nearly $49 million over 75 years, in maintenance and operation costs. Avoided costs include replacing, updating and operating fire- and life-safety systems for the snowshed, as well as electricity and ventilation costs.
“I-90 is a key economic corridor in our state, moving people to their destinations and millions of tons of freight a year, much of it headed to our ports,” said Paula Hammond, secretary of the Washington State Department of Transportation. “This bridge solution in this avalanche-prone area helps keep the highway more operational in the wintertime, and also saves a significant amount of money.”
Cost of building the bridges is about the same as the cost of a new snowshed. Construction cost of the final two miles of the project is approximately $180 million.
During early design of the I-90 project, WSDOT looked at four alternatives, including a bridge that would be built partially into Keechelus Lake. However, a team of engineering experts recommended WSDOT not build bridges because of engineering and environmental challenges from whiteout conditions during a large avalanche – making a new, wider, longer snowshed the choice at the time.
However, after months of collaboration, WSDOT and the contractor came up with a bridge design that addresses whiteout conditions by building the structures high enough to accommodate avalanche chutes and digging into the chutes and channeling them to go under the new bridges.
Total cost of the five-mile improvement project from Hyak to the Keechelus Lake vicinity, paid for by the 2005 gas tax, is $551 million. Guy F. Atkinson Construction was selected to build the final two miles of the project, which is widening the highway from four to six lanes, and replacing the snowshed. Max J. Kuney Inc. is constructing the first three miles of the project. The entire five-mile project is scheduled for completion in 2017.