Huge Boulder Slows Traffic Rock `Size Of A Small House’ Rolls Onto Montana Road

A boulder as big as a small house tumbled off a mountainside onto U.S. 93 early Friday, apparently loosened by rain and vacillating temperatures.

Highway Department workers had to use four blasts of a plastic-type explosive just to reduce it to pieces small enough to move off the road, said Stephen Herzog, maintenance chief for the Kalispell division.

“It was the size of a small house,” he said. “This was not your typical boulder.”

Witnesses estimated the rock was about 15 feet long, 15 feet wide and 12 feet high. It slowed, but did not block, traffic.

Herzog said workers used relatively light loads of explosive because a fiberoptics line and power lines passed above the boulder.

About two-thirds of the rock was trucked away Friday, and the remainder will have to be reduced with further blasting, Herzog said.

“It was a great big portion of the hillside,” he said. “I estimated it was up there 400 or 500 feet and just came rolling down.”

It landed in the southbound lane of U.S. 93 about 4-1/2 miles south of Lakeside and 15 miles south of Kalispell. The Lake County sheriff’s office received a call about 5 a.m.

Neither the rock, the blasting nor the moving equipment caused any damage to the roadway, Herzog said.

Workers saw no other dangerously loose rock at the site, and he knew of no other dangerous spots in the area, he said.

“This is the time of year when there’s always the opportunity for fallen rock to be in the road,” Herzog said. “Motorists just have to be aware.”