The Washington State Department of Transportation is finishing construction on the first I-90 archway for animals east of Keechelus Lake. Eventually, the 15-mile stretch of freeway will feature 27 animal crossings, most of them underpasses.

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Just east of Keechelus Lake on Interstate 90, construction crews have been lifting and stacking 40,000-pound blocks of concrete and rebar side-by-side. By the end of the week, 39 will line each side, forming an archway over the roadway’s westbound lanes.

For environmental groups, the hunks of concrete are a welcome sight. Eventually, a forested bridge will span westbound/eastbound archways, giving bears, deer, elk and other creatures freedom to roam across the highway without playing a real-life (or death) game of “Frogger.” It will be the state’s first freeway overpass for wildlife. Proponents say the bridge and other crossings along 15 miles of I-90 will promote biodiversity, prevent motorists from splattering wildlife and help critters tolerate climate change.

“Highways are one of the greatest fractures to wildlife habitat, and the idea that we can reconnect with the same cement — it’s tremendous” said Jen Watkins of Conservation Northwest.

The wildlife crossing, which the Washington State Department of Transportation (WSDOT) has slated for completion in 2019, is part of a suite of updates to I-90 east of Snoqualmie Pass, including two new avalanche bridges, rock-slope stabilization and other updates. Highway traffic has been redirected and reduced to four lanes in some areas as WSDOT renovates the route.

Eventually, the 15-mile stretch will feature 27 animal crossings, most of them underpasses, engineers said. Four are finished. Motorists will pass by most without a second thought because they’re designed for animals to cross underneath or through enlarged culverts.

But this development stands out. The archway can be seen by motorists between mile markers 61 and 62.

Fences will funnel animals toward the 66-foot-wide overcrossing, which will be topped with soil, trees and other native plants. Rock piles will host pikas and salamanders. Ten-foot walls on either side of the bridge will keep out the glare of cars’ passing headlights.

“The idea is you’re just walking in the forest,” said Brian White, assistant regional administrator for construction and development at WSDOT.

Some species, particularly large predators and migratory mammals, prefer overpasses, said Charlie Raines, director of the I-90 Wildlife Bridges Coalition.

“Elk like open. They don’t like stuff above their head,” he said.

A report on crossings in Canada found grizzly bears, wolves, moose and deer nearly always chose overpasses to cross roadways. Cougars, meanwhile, are more comfortable crossing below.

The bridge will let those ranging predators travel and mingle on both sides of I-90, which should promote biodiversity, Watkins said. That’s particularly important for rare, endangered species like wolverines, she said.

Safe access to land south of I-90 could boost species like wolves looking to expand their range. Last spring, about 10 miles from the project, a wolf was found dead on the interstate.

As climate change pushes temperatures higher, some species will need the bridge to migrate, Raines said.

Renovations on I-90 will continue through 2027. Last year, the Legislature gave $426 million to fund the last three phases of the project, including two more overcrossings near Easton.