Billings public works officials await a more thorough evaluation of the geology of some of the precarious rocks above Zimmerman Trail before making the repairs necessary to reopen the closed portion of the roadway.

The decision and subsequent action will occur sooner rather than later, Vern Heisler, deputy public works director, said Friday.

The Montana Department of Transportation had scheduled a project that includes preventing future slides and widening a portion of Zimmerman Trail, work that also includes an overlay and new guardrails. But those projects won’t be completed until up to 18 months from now, Heisler said, and local officials and travelers certainly don’t want Zimmerman Trail closed any longer than need be.

The MDT project has been split into two phases because what’s discovered during the first phase — rock remediation — will guide the second phase, Heisler said.

A rock slide Tuesday afternoon forced closure of Zimmerman Trail between Rimrock Road and Highway 3. A crew from Terracon, a Billings geotechnical and environmental assessment firm, was on the scene Friday, hiking up the Rims and evaluating the slide.

Heisler said that a Terracon geological engineer is scheduled to perform a follow-up and in-depth evaluation of the chances for future rock slide danger next week.

“We hope to do a smaller project up front to take care of the rocks. That would allow us to open the road back up,” he said. “Waiting for the MDT projects is not what we want to do.”

A three-person crew from Terracon was on the scene Friday morning using Global Positioning System technology that will map the affected area within 1 inch of accuracy.

Heisler said that during next week’s engineering analysis, special attention will be paid to the rock next to the rocks that fell down the slope Tuesday.

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He said he and Public Works Director Dave Mumford will keep Mayor Tom Hanel and the City Council up to date on the engineer’s report, which will first be presented to the city’s engineering division.

“When we know something, we will definitely let the mayor and council know,” Heisler said. “It is a vital transportation link in the city.”

At least one homeowner who lives below the rock slide said she wasn’t too worried about the potential of damage to her home by a future rock slide. The main concerns for Karen Sampson, who lives on Edmond Street with her husband, Greg, just below the closed portion of Zimmerman Trail, are twofold: speeding traffic on Zimmerman Trail and the amount of water that rushes off the Rimrocks and gushes through her backyard each spring.

She said she also worries that the more rock that’s removed, the greater the “waterfall” that ends up in her yard each spring.

Those worries are coupled with the inconvenience caused by drivers using her driveway to turn around once they realize that Zimmerman Trail is in fact closed. A large sign and a locked gate placed by public works crews apparently are insufficient warning for some drivers.

“People don’t read signs,” she said, shaking her head.

As crews move rocks that they’d earlier piled up in a maintenance turnout off Zimmerman Trail, Sampson said she had an idea for a sign she’d like to erect in her yard.

“I should just leave a sign out,” she said, “that says, ‘Hey! I need that one to decorate my yard!’”

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City Government Reporter

City reporter for The Billings Gazette.