EAGLE COUNTY — Here’s a rite of spring older than rising gas prices: the annual freeze-thaw cycle that drops rocks — sometimes big ones — on area roads, highways and other, less-public areas.
The local rockfall season started with a bang this past week, when a big part of Lionshead Rock above Minturn tumbled into the valley. No one was hurt, but the (mostly unused) railroad track through town sustained heavy damage, as did a high-pressure natural gas line. In nearby Mesa County, Colorado Department of Transportation crews took several days to clear a large slide on Colorado Highway 65 just south of Interstate 70.
While Lionshead Rock was the most obvious boulder to fall so far this year, rocks have been hitting local highways for a while now.
Jim Achatz is the department of transportation’s maintenance supervisor for this part of Eagle County, including I-70 and U.S. Highway 24 over Battle Mountain. He said crews have already pulled tons of rocks off the roadway on Battle Mountain. It’s a never-ending job this time of year.
“We send someone up three times a day, at least,” Achatz said. “This time of year, you’ll have rocks coming down just about every hour.
Most of the time the rocks can be pushed to the side of the road with a plow truck or picked up and put in the truck bed. But, Achatz said, his crews have already had to send a loader up Battle Mountain several times to pick up bigger, heavier rocks, some of which have been roughly 5 by 5 feet.
DANGER FOR MOTORISTS
Rocks on the road can always damage a car — even a collision with a rock the size of a soccer ball could result in some expensive repairs. What really worries Achatz, though, is the prospect of a motorist hitting a rock, then somehow driving off the road.
Other parts of Eagle County aren’t as potentially dangerous in terms of the potential to fly off a cliff, but there are plenty of other spots where a wayward rock can wreak havoc with a car’s undercarriage. Achatz’ crews spend plenty of time in the westbound lanes of I-70 in Dowd Canyon, between the West Vail and Minturn interchanges. Concrete barriers catch most of the rocks, but some do hit the highway.
Achatz said there are also parts of U.S. Highway 6 that need a good bit of watching this time of year.
The Eagle County Road and Bridge Department takes care of most of the roads in the area, including the Colorado River Road that links Dotsero with State Highway 131 north of State Bridge. Department director Gordon Adams said his crews will send a truck up the river road at least once a day when the weather is right.
WEATHER TRIGGERS SLIDES
But what is good rockfall weather?
Ty Ortiz, the geotechnical program manager for the Colorado Department of Transportation, said what prompts rocks to fall is a combination of warm days and sub-freezing nights. Often, that means water, in the form of melting snow, works into crevices in rock faces, then freezes and expands, loosening the rocks.
Other times, the simple expansion and contraction from the heating and cooling can work rocks loose.
While the rockfall season is just starting, we’re still a few weeks away from landslide season, which starts as snow starts melting in earnest. The difference between a rockslide and a landslide is, roughly, that a rockfall will drop footballs, while a landslide will drop the whole field.
In fact, landslides can make a much bigger mess, Ortiz said. Some of those places won’t melt until June.
On rare occasions, rocks will fall from mountains and hit a vehicle, with tragic results. Most of the time, though, motorists just need to be on the lookout for rocks on the roads.
Keeping a sharp eye on the road usually means slowing down, Achatz said, so motorists have time to either stop of swerve if they come around a blind corner and see a rock the size of a briefcase, a kid or, sometimes, a car sitting in the road.
“We try to do everything we can,” he said. “That damage (from rocks) is an added expense a lot of motorists don’t need.”