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Crews keep wary eyes on unstable slopes

Maintenance crews from districts 2 and 3 worked nearly side-by-side this week to keep traffic flowing on U.S. 95, despite rock and mudslides.

Relentless rain on steep slopes above the highway sent mud and rocks onto the highway at milepost 177, about 14 miles south of Riggins. ITD closed the highway at about 8:30 a.m. Sunday and urged motorists to choose a western route into Oregon to avoid the area. Both lanes of the highway in District 3 reopened to traffic at about 4 p.m.

Eleven miles away, an unstable slope shed “car-sized” boulders onto U.S. 95 near the Sheep Creek Safety Rest Area. Travel was limited to a single lane early in the week but was fully restored late Tuesday afternoon.

Cooler temperatures and frozen slopes usually tend to hold material in place during the winter; rock and mudslides are more common when ground thaws in the spring. But a relatively mild fall with steady rain makes the slopes vulnerable to slides.

District 2 maintenance engineer Doral Hoff told a reporter the slope failure was “just old rocks. They just had finally found a slip plane to break free of.”

Motorists are urged to use caution when traveling near steep slopes and to watch for debris that might find its way onto the highway. ITD crews remove the material as quickly as possible to maintain traffic flow.

Weekend forecasts call for cooler temperatures in higher elevations of central Idaho with the likelihood of snow showers. Lower elevations could experience a mixture of rain and snow flurries.