Avalanche control on Lizard Head Pass by the
Every winter north of Rico, the Yellow Springs Wall, Yellow Springs Gully and Peterson avalanche paths fill with snow and threaten to bury Colorado Highway 145.
“When we experience heavy snows, these slide paths can be frequent offenders for snow hitting the highway,” said CDOT Avalanche Program Coordinator Brian Gorsage.
His crews handle and launch explosives from long-range guns to trigger avalanches on closed highways, then crews plow the snow. They use “Avalaunchers” to fire projectiles at the snowslide area, or a howitzer cannon that shoots ammunition into the Lizard Head Pass slide path areas when necessary.
But to improve efficiency and protect workers, blasting this winter will be detonated remotely from five, 30-foot-tall towers positioned near the slide paths.
Wyssen Avalanche Control, based in Switzerland, is installing the units on mountain slopes and ridgelines in August and September.
When triggered by remote control, a pressurized cannister of gas attached to a tether is lowered to a preset height above the slide path, then detonated.
“The concussive blast triggers the controlled avalanche. We do not want them to slide naturally because of the threat to the traveling public,” said CDOT spokeswoman Lisa Schwantes.
CDOT’s Avalanche Mitigation Program will operate the system. Gorsage said CDOT has been working with the San Juan National Forest for the past year to obtain permits for the installation.
Remote systems have proved more reliable and safer for avalanche mitigation personnel, CDOT said. They also provide faster and more efficient avalanche control operations, making travel in the area safer for motorists.
“Colorado 145 and Lizard Head Pass is the alternate route for travelers heading north when the U.S. 550 mountain corridor is closed for emergencies,” said Jamie Yount, manager of CDOT winter operations programs. “This new avalanche mitigation system will help us keep CO 145 open more readily, offering a higher, more dependable level of service for motorists, particularly when avalanche conditions and cycles are occurring in the San Juan Mountains during significant winter storm periods.”
To trigger an avalanche, a coded command is sent by remote to the deployment box on top of the tower. The deployment box contains 12 explosive charges.
When the explosive charge is dropped, two igniters are pulled, and the explosion is set off after a time delay. The charge remains hanging from a cord, which is completely dropped after blasting. To reload explosive charges, the complete deployment box is lifted from the tower by helicopter and taken to a station building.
Installation of the remote control units will take place on Colorado 145 over six to eight weeks beginning Aug. 4. Generally, motorists should expect minimal traffic impacts because most work will take place off the highway.
Regular work hours are Monday through Friday from 8 a.m. to 4 p.m. No weekend work is anticipated. Traffic in the work area will be limited to 40 mph.
CDOT operates more than 30 remote systems at several locations on high mountain highways and the Interstate Highway 70 corridor.
Every winter, CDOT and its sister agency, the Colorado Avalanche Information Center, monitor and control about 278 of 522 known avalanche paths above Colorado highways.
jmimiaga@the-journal.com
