Since the early 1950s, WWII artillery has been a critical asset for the Colorado Department of Transportation (CDOT) in the seasonal fight against avalanches in the Colorado Rockies. However, now plans are being drawn up to phase out these large guns.
While the artillery in operation has changed over the years, currently, CDOT reports operating seven M101A1 Howitzers in their avalanche mitigation efforts.
"They're surplus World War II weapons that we lease from the Army," Brian Gorsage, the state avalanche coordinator for CDOT, said.
These artillery pieces are used in addition to other explosive methods such as helicopter bombing, hand-thrown charges, shelling from air cannons, and a number of remote operated systems.
When needed for mitigation purposes, these large guns, capable of firing rounds up to a distance of seven miles, are towed to their designated locations:
- Two in the Loveland Pass area
- Two in Wolf Creek Pass
- Three between Coal Bank, Molas, & Red Mountain Pass
Depending on the snowfall, Gorsage said they'll utilize the Howitzers to fire off anywhere between 250 and 500 rounds in an average year in order to bring down avalanches.
We have [standard operating procedures] through the army and we have another group [Avalanche Artillery Users of North America Committee] that outlines what we can and cannot do with this weapon. We train every year, multiple times a year and including our missions to keep our crews up to date and proficient at what they do.
However, the era of firing military-grade weaponry at avalanches is starting to come to a close with CDOT looking to newer technologies for their snow-fighting needs.
The army has just asked us to reduce our dependency on these weapons as they age, these, like I said, are World War II era weapons; they function phenomenally and are extremely accurate, but there are some new technologies that are available to us that give us more flexibility in what we do.
These newer technologies are generally referred to as Remote Avalanche Control Systems (RACS).
CDOT reports having installed about 50 RACS along avalanche paths as of April, 2024.
One of the more recent RACS installations saw five new devices positioned above Red Mountain Pass — an area Gorsage said might be one of the most troublesome of the mountain passes in December, 2023.
Two Gazex units were permanently installed at slide paths on Red Mountain Pass between Silverton and Ouray. The Gazex units will remain in place year-round. Three O’bellx units were also installed 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 purposefully triggered avalanche under controlled conditions — a closed highway with no traffic.
According to CDOT, the RACS (mentioned above) also include the following benefits:
- Gazex and O'bellx systems are safer to operate than those that use explosives
- The remote-controlled systems will enable more efficient avalanche control, making the areas safer for CDOT crews and travelers
- The systems can be operated at night, allowing CDOT maintenance crews to clear the road before morning
CDOT also employs systems such as Wyssen Towers and Avalanche Guard.
Tentative plans indicate that depending on funding sources, CDOT could phase out the Howitzers by the end of the decade. However, Gorsage reports that the Army has not given CDOT a strict timeline.
Currently, through the usage of "explosives and gas-based systems," CDOT reports that they cover more than half of the state's avalanche paths.
Every winter, CDOT and its sister agency, the Colorado Avalanche Information Center (CAIC), regularly monitor and control 278 of 522 known avalanche paths located above Colorado highways. This helps prevent avalanches from impacting drivers and passengers on the highways below. To help predict avalanche conditions and the necessity for avalanche control, CDOT and CAIC study forecasts and current weather conditions.
According to Gorsage, Colorado's avalanche season can run from October to June, but December through April makes up the "meat of the season."
"It's definitely getting into a season where things are melting," Michael Chapman, Winter Operations Manager for CDOT, said. "The snowpack is becoming more unstable as it melts and re-freezes and melts; this is the time of the year where some of the snow in the passes will release because of that."