Driving through Wyoming on Highway 89/191, just south of Jackson, you might think you've landed in the twilight zone when you see a row of sails. Sailing in the Rockies? Actually, what you see are snow sails, designed to ease the effects of avalanches.

The Wyoming Department of Transportation Thursday completed the installation of 50 "snow sails" in the area, which is notorious for avalanches. WYDOT hopes the devices will save lives and help the environment.

The green 10-foot by 8-foot sails mounted on 14-foot-high aluminum booms are part of an effort to mitigate the effects of slides in the area that in the past have taken vehicles off the road. The project should make it safer and reduce delays for travelers using this major route into Jackson.

WYDOT District Engineer John Eddins said the agency periodically closes the highway for avalanche-control work.

"Sometimes, a rapid rate of snowfall causes a buildup so quickly that the weight of the snow on the slopes results in a slide before we can get the road closed and break up the unstable snowpack."

The snow sails have a long history in Europe, dating back to the late 1940s and early 1950s, but this is the first full-scale test of the devices in the United States.

In addition to the sails, a tree-planting program will be instituted next year. Ideally, the trees will help stabilize the area and contain the snow to the point that use of the sails could be discontinued.

The north-facing sails, fastened with 3-foot-long anchors, are placed about 15 feet apart from the top of the ridge about two-thirds of the way to the road level. They will deflect some of the snow blown into the area from the prevailing southerly winds.

By manipulating the wind, the department anticipates the snow will be deposited into a series of smaller bumps of snow that will be less prone to sliding.