Every winter, frustrated drivers add hours to their trips when Interstate 90 over Snoqualmie Pass is closed for avalanche control.
But a newly approved plan that continues major construction on the pass should help: The proposal will transform a section of the freeway into two 1,200-foot-long bridges that will allow snow and debris to slide down the hillside and under the roadway, eliminating or drastically reducing those winter avalanche delays.
“It’s designed to take the worst of the worst of the worst of everything,” said Phil Larson, a project manager for Guy F. Atkinson Construction, the contractor that pitched the bridge proposal in lieu of the state’s plan to replace the 500-foot snowshed that shields the roadway.
Construction this summer will include delays for rock blasting during several nights, but should otherwise have little effect on drivers, officials say.
The bridge proposal is the latest step in the State Department of Transportation’s long-term improvement work on Snoqualmie Pass, which began in 2010. The 5-mile project will expand the freeway to three lanes in each direction, stabilize rock slopes and extend chain-up areas for trucks, to the tune of $551 million.
Construction under way encompasses the 2.5 miles of freeway between Hyak and the western side of the snowshed. Max J. Kuney Construction of Spokane is set to finish on schedule in 2013.
For the next 2.5-mile phase, transportation officials initially envisioned replacing the current tunnel-like 62-year-old metal snowshed, which covers about 500 feet of the two westbound lanes.
The replacement would have been 1,200 feet long and stretched over all six lanes of the revamped interstate, spanning the five avalanche chutes that cause the bulk of winter problems.
But when Atkinson won the bid, the company offered an alternate plan: Two raised bridges, high enough that avalanches could slide underneath.
The bridges eliminate federally required safety measures inside the snowshed, such as adequate ventilation, lighting and fire protection.
“Everyone saw immediately the benefits of not having a long-term operating and maintenance risk of a snowshed and its electrical and mechanical systems,” said Bob Adams, vice president of Atkinson. Cost savings are estimated to be $650,000 a year.
This week, the Transportation Department will give the company the official go-ahead to begin construction.
The construction site runs from the western side of the snowshed to just beyond Keechelus Dam. It’s not scheduled to be completed until 2017, so drivers can expect some level of disruption from April through October every year until completion.
But the company is committed to keeping two lanes of traffic open in each direction at peak travel times, said Brian White, assistant regional administrator for I-90 construction.
“We’ll try to minimize the effect to the public as much as we can,” he said.
On weeknights this summer, he said, drivers should check the WSDOT’s website before traveling across the pass, as crews will be rock blasting several nights a week. The blasting starts an hour before dusk, and the freeway generally is closed for about an hour each time.
Cost of the bridges is about the same as the proposed snowshed, officials say – about $71 million of the total $551 million project, paid out of a 91/2-cent state gas tax implemented in 2005, which also funds several other road projects.
The WSDOT is working on improvement plans for the next five miles, but that section of the project has no funding source yet.