It’s rockslide season, and Colorado’s hazard team is using new technology

Scott Miller
Vail Daily
Steel nets do the best do protect roadways like Highway 24 on Battle Mountain Pass on Saturday, April 14, in Minturn. Spring brings about an uptick of earth movement.
Chris Dillmann/Vail Daily


Rockslides and mudslides can have several causes. Here are two of the most common.

• Snow can thaw during the day, sending water into cracks in rocks. That water then freezes and expands at night, making cracks larger.

• Melting snow can saturate ground, leading to landslides.

EAGLE COUNTY — The same time of year that brings blossoming daffodils and singing birds also brings something more dangerous: rock slides. Now, technology is helping crews better identify slide zones.

The Colorado Department of Transportation has started work on a rockslide mitigation project in Glenwood Canyon. That work will include cleaning out rockfall catch fences and upgrading some of the older fences.

The work will cause some delays on Interstate 70 through the canyon. Still, it’s better than the delays caused by rockslides.

In 2016, a substantial part of a slope in the canyon slid onto the roadway, causing some major delays — and a roughly 200-mile detour around the canyon — and several weeks of repair work and evaluation by CDOT’s geohazard team.

But Glenwood Canyon is just one spot in a large network of roads. There are slide zones across the Rocky Mountains and in other places.


Back when CDOT measured just rockfall zones, here were more than 700 such areas.

These days, the geohazard crew takes a broader approach. Ty Ortiz leads the department’s geohazard team. Ortiz said now his team looks at geology ranging from obvious rockfall and landslide areas to places where flash floods can create debris flows, where water can create sinkholes or where water can undercut road embankments.

That’s a lot more territory to watch, and water is the common denominator among most of those hazards. Whether its flash flooding or the more slow-motion damage caused by melting snow, watching water and where it flows is a crucial part of the geohazard team’s work.

A lot of that work, particularly in rockslide zones, requires old-fashioned climbing to evaluate boulder fields and other hazards. But technology may be making the geohazard team’s work a bit less dangerous and more precise.

The team has started using drones to map hazardous areas — Ortiz called it “aerial data collection.” That mapping can provide the team with information about whether a slide zone is moving or starting to move.

Ortiz said the technology is still in its early days, adding that there’s still no current substitute for hands-on evaluation.

But James Hagadorn, of the Denver Museum of Science and Nature, said aerial mapping can potentially give crews a chance to catch hazards before they start.

Ortiz said aerial mapping can also give his team a good idea of where to send a geologist.


The technology gives Ortiz and his team a chance to “be proactive to geologic hazard by being reactive to geologic data,” he said.

Using data, crews can decide how they need to learn more about a hazardous area, whether that’s installing new instruments at a site, closing a road because something bad is about to happen or putting crews on a site before a major slide hits.

In the case of big rocks, that can mean blasting big pieces into smaller ones.

“A block the size of a house will do a lot of damage,” Ortiz said.

A few years ago, a rock the size of a truck fell down from the north wall of Glenwood Canyon, punching a hole in the westbound road deck on the western exit of the Hanging Lake tunnels. Being able to blast a rock that size into smaller bits could have prevented at least some of that damage.

While Colorado isn’t the only mountainous state, CDOT’s geohazard team is one of only a few in the country.

And, Hagadorn said, Colorado’s team is one of the best. Similar teams come from around the country and the world to study what’s being done.

Still, rocks are going to fall.

Red Cliff resident Scott Burgess commutes to work in the valley. That means he has to dodge his share of rocks. Burgess said the rockfall fences above the hairpin curves just to the south of Minturn seem to have worked as intended.

Mostly, though, he said the key is “don’t stop, and pay attention.” And, he added, “If Mother Nature decides to drop a (bus-sized rock) on you, there’s not much you can do about it.”

That may start to change in the near future.

Vail Daily Business Editor Scott Miller can be reached at 970-748-2930 and