AASHTO Journal - Colorado DOT Installs New Avalanche Mitigation System

The Colorado Department of Transportation recently installed and safely tested new avalanche mitigation equipment above U.S. Highway 550 on Red Mountain Pass, between Silverton and Ouray.

[Above photo by the Colorado DOT]

Two “Gazex” units were permanently installed at slide paths on Red Mountain Pass between Silverton and Ouray, along with three “O’bellx” units at another location on Red Mountain Pass. The O’bellx base features are fixed and permanent, while the portable units holding the gasses require resetting on site each winter with a helicopter.

The systems – remotely controlled with mobile devices like a cell phone or tablet – operate by using compressed air and gasses to create a concussive blast to trigger slides at the top of high-risk avalanche zones.

The force of the explosion is directed down toward the snow, producing a purposely triggered avalanche under controlled conditions — a closed highway with no traffic, stressed the agency

“Our specially trained avalanche crews have tested the five new units and we are ready for winter,” said Brian Gorsage, Colorado DOT’s state avalanche program coordinator, in a statement.

“These snow slide paths on Red Mountain are known as frequent offenders. Our crews shoot these down many times throughout the winter season,” he said. “Now with these units permanently installed and pre-loaded on the mountain and ridgelines, operations can take place in the early morning hours before daytime commuter traffic increases, lessening closure impacts for motorists.”

Julie Constan, the agency’s southwest regional transportation director, also emphasized the enhanced benefits of the new mitigation systems. “We look forward to these systems helping our maintenance crews keep Red Mountain Pass passable for local residents and visitors,” she noted. “This advanced technology also means safer operations for our personnel, more efficient missions and reduced durations of roadway closures.”

The installation of the new avalanche mitigation system – which took place this summer and fall by agency contractor Geovert – resulted from a unique collaboration between Colorado DOT’s engineering and maintenance divisions, noted Jeff Reichel, Colorado DOT engineer/project manager

“CDOT engineers typically work on projects like road paving, bridge building and culvert replacement,” Reichel said. “This project took place in a high alpine environment requiring all the construction equipment and supplies to be delivered and installed by helicopter and rope access technicians. It was quite a challenge for our construction team.”

Every winter, Colorado DOT and the Colorado Avalanche Information Center or CAIC monitor 522 avalanche paths located above many Colorado highways and I-70. They use explosives or gas-based systems to reduce the hazard in 278 of these paths.

“[We] work together to monitor and plan mitigation missions that ultimately prevent hazardous natural avalanches from impacting public travel,” explained CAIC Director Ethan Greene. “CAIC is staffed with forecasters across the state. These forecasters assess the avalanche conditions and assist CDOT crews with determining when avalanche control operations are required to keep mountain roads safe for residents and other travelers.”

When there is a high risk of avalanche danger, CDOT will close highways at the locations of the avalanche paths in order to conduct avalanche control operations. While the road is closed to public travel, avalanches are triggered. Maintenance crews with heavy equipment then clear the highway of any snow and debris that reached the road. The highway can then be re-opened for safer public travel.

Colorado DOT operates more than 40 remotely-controlled systems at several locations across the state, including on U.S. 50 Monarch Pass, U.S. 160 Wolf Creek Pass, CO 145 Lizard Head Pass, the I-70 mountain corridor, U.S. 40 Berthoud Pass and U.S. 6 Loveland Pass. The five on Red Mountain Pass are the first fixed systems to be installed on U.S. 550, the agency said.