Dive summary:

• The Washington state Department of Transportation and its contractor, Guy F. Atkinson Construction, have devised a bridge plan to carry Interstate 90 over avalanche snows in the Snoqualmie Pass east of Seattle rather than trying to pass the snow over the highway.
• Since the 1950s, a concrete structure known as the snow shed has covered westbound I-90 in an area where a steep mountainside comes down to meet Keechelus Lake, and the shed needed replacing as part of an I-90 reconstruction project.
• Atkinson was concerned, however, that building a bigger shed over the whole highway would mean working over moving traffic, and the solution now approved by the state and the Federal Highway Administration will be bridges designed to channel even the heaviest avalanche under the road on its way to the lake without harming bridge piers.

From the article:

This design will reduce the number of closures of I-90 due to avalanche control work as well as reduce maintenance and operations costs. ...