Crews for the Washington State Dept. of Transportation have checked off key projects along Interstate 90 before closing up shop for the winter.

As crews wrapped up the season of work on I-90 east of Snoqualmie Pass, they clean up a job site that includes a new two-mile stretch of wider roadway about nine miles east of the Snoqualmie Pass summit, a new avalanche bridge that opened to traffic in late summer and the early stages of the westbound wildlife overcrossing.

This work continues as part of the major project to widen I-90 from four to six lanes between Hyak and Easton just east of the summit on an interstate that connects Seattle to Spokane on its way to Boston as the longest interstate in the country.

Since April, crews have worked to replace about four miles of deteriorating roadway sections near Easton, not counting another 15-mile section farther east in Ellensburg and a new paint job at the Vantage Bridge over the Columbia River. New traffic cameras and electronic message boards near Ellensburg were also installed this season.

But just because work wrapped for winter doesn’t mean crews won’t be back next spring in full force, continuing the $551 million effort to construct two avalanche bridges as part of the project, while stabilizing rock slopes. Work started in 2009 and the final two-mile section should wrap up in 2018, even as phase two continues into 2019. The second phase, which started last year, includes additional stabilization of rock slopes, bridge replacement and the first wildlife overcrossing in the project corridor.

The project aims to widen the roadway over the busiest mountain pass in the state, but also straighten curves, upgrade bridges, expand chain-up areas and address wildlife connectivity.

Follow Tim Newcomb on Twitter at @tdnewcomb