Colorado transportation officials plan to nearly double the number of remotely controlled avalanche blasters installed on mountain ridges above highways, a project estimated to cost taxpayers tens of millions of dollars to prevent potentially catastrophic snow slides.
They’ve settled on a strategy of firing these blasters at night to trigger slides as part of efforts to keep roads across the western half of the state safe and open for trucks, tourists and residents of growing communities.
Bolted and cemented into delicate tundra at elevations up to 12,600 feet, some of these mechanisms ignite propane, oxygen and hydrogen gas in concussive blasts, while others dangle explosives from 30-foot metal towers over slide paths.
The Colorado Department of Transportation has been firing 54 blasters about 200 times a year to pre-empt natural avalanches. An updated state inventory shows highways, including Interstate 70, running through more than 500 avalanche paths.
The remotely detonated night blasts add to another 400 blasts conducted during the daytime by CDOT crews firing 70-year-old Army howitzer artillery cannons into snow-laden mountainsides, dropping bombs from helicopters and deploying teams of skiers who carry explosives in backpacks.
CDOT’s expansion to install 50 more Remote Avalanche Control Systems, pending approvals from the U.S. Forest Service, would start this summer along I-70 above the east portals of the Eisenhower-Johnson Memorial Tunnel, where 6.1 million vehicles roll each winter, and then shift to southwestern Colorado along Wolf Creek Pass east of Pagosa Springs and Coal Bank, Molas, and Red Mountain passes north of Durango.
“You see an orange flash and hear a giant boom,” said CDOT avalanche control coordinator Brian Gorsage, whose teams park near blast sites and use smartphones or laptops to detonate explosions.
But the avalanches triggered at night, when traffic is lowest, still often hit roads. This happened on Dec. 30 along Berthoud Pass. Gorsage directs pre-positioned snowplows (CDOT runs a fleet of 876) to clear snow chunks, trees and rock debris as quickly as possible — ideally before sunrise to minimize delays.
CDOT studies estimate a $1.6 million hit to the Colorado economy for every hour that I-70 must be closed for avalanche control, which happened four times in 2024.
Controlling avalanches after snowstorms “is part of life along our high-altitude mountain passes, roads that go up to 11,000 feet. This is the best way forward,” Gorsage said. “Getting everyone going to where they need to go is a super high priority. We are manipulating Mother Nature to protect our transportation system.”
Since the early 1900s, avalanches have killed 16 drivers along Colorado highways, according to Colorado Avalanche Information Center records.
CDOT began an avalanche safety program after state snowplow driver Eddie Imel was killed in March 1992 by an avalanche on U.S. 550 (Red Mountain Pass). No drivers have been killed in avalanches along highways since then.
But avalanches regularly hit vehicles:
- Last year on Jan. 24, an avalanche on the west side of Berthoud Pass (U.S. 40) hit 10 vehicles and forced 72 hours of closures
- On March 7, 2019, an avalanche that ran 1,000 feet through timber near the Copper Mountain ski area caught four vehicles along Colorado 91, burying a pickup and toppling a Subaru into 12-foot-deep debris
- That month, on I-70 between Frisco and Copper Mountain, an avalanche ripping down a chute on the east side of the highway crossed a creek, sending airborne blasts of snow that blinded drivers and partially buried two cars and forced the closure of I-70
Drivers in each case were able to escape or were extricated without injury.
Beyond roads, avalanches increasingly hit people, mostly backcountry skiers, snowmobilers and snowshoe hikers. The number hit by avalanches has increased to 148 in 2024, up from 53 a decade ago and 45 in 2007, Colorado Avalanche Information Center records show.
Avalanches occur naturally in the Rocky Mountains and play key roles in forest ecology. The Colorado Avalanche Information Center documents about 5,000 a year and estimates nature produces 25,000 to 50,000.
It is getting harder to predict when and where they will hit, CDOT’s chief meteorologist Mike Chapman said.
“We’ve seen an increase in avalanches. We can infer there’s likely some climate change influence there,” Chapman said. A pattern over the past two years, where snow falls early in November followed by several dry weeks, sets up conditions that favor avalanches.
“It’s an abnormal dry start to the winter that weakens the snowpack,” he said. “You put snow on top of it and it slides.”
U.S. Army officials have been urging modernization of avalanche control in Colorado, Utah, Wyoming, California and other western states. Ski areas already deploy computer-controlled blasters, developed in Europe, where civilian use of military weapons is prohibited. CDOT officials have set a goal of becoming “howitzer-free” on I-70 and phasing out the state’s seven howitzers by 2030.
“Especially in southwest Colorado and east of the Eisenhower Tunnel, we’re still using military artillery. These are weapons systems built for war that we are using for civilian public safety. It’s been a very effective program over 50 years, but it’s not the best we can do, in this day and age, using weapons of war for this purpose,” said Ethan Greene, director of the Colorado Avalanche Information Center. “Some systems we’re using are from the Korean War. We’re going to run out of pieces and parts. And the modern artillery systems are too much for what we need — just not a very good fit for what we are doing.”
Colorado began installing remote-control blasters in 2015 above Berthoud Pass, a critical link between Denver and northwestern Colorado, trying to replace unexpected big natural slides with frequent small ones.
Forest Service officials approved the installation of 54 blasters after weighing visual impacts, harm to wildlife and plants, erosion, pollution and damage from construction and summer maintenance of gas hoses and fittings.
CDOT officials are lining up dollars — “tens of millions in capital investments, followed by 5% to 10% of that each year for maintenance,” Gorsage said. Agency officials declined to provide a more specific price tag for the project.
Federal officials still must sign off on installing the 50 additional blasters.
Colorado mountain towns and the ski industry have strongly supported the shift to remote-control blasting at night.
Grand Lake Mayor Steve Kudron, a Colorado resident since 1976, lauded this approach as “miles ahead of what we experienced in the past” when CDOT crews often closed Berthoud Pass.
The 5 a.m. blasts on Dec. 30 to trigger an avalanche that hit the highway required hours of snowplow clearing, but traffic was flowing by 7:25 a.m., Kudron said, and he ferried his in-laws to Denver International Airport in the usual 2.5 hours.
Grand Lake residents are mostly part-timers, second-home owners who rely heavily on easy road access to reach places where they can ride snowmobiles and ski cross-country, Kudron said.
Blasters bolted into the high mountain tundra “don’t quite blend in,” he said. “But we continue to advocate for safer conditions that will let us have fewer and fewer incidents when we cannot get over the pass.”
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