Road crews battle avalanches with fire and iron
By Lauren di Scipio Kinsner
There are days when the coffee in my cup ripples from the munitions blasts rocketing projectiles at the snowy peaks. On other days, I can hear the distinct, deep, muffled sound of tons of powder and ice finally giving way on its own, sliding down the chutes and landing with that heavy T H U D. It’s a sound that is somehow soothing when I am safe and warm a mile away, and another reminder of how amazing it is to live in Alaska.
That is not an earthquake or thunder. That is an avalanche.
And it’s not a sound that you want to hear while driving along Turnagain Arm. When we chose to live in Bird, we were warned about the tailgaters, ice, rock fall and avalanches. But the beauty here is seductive.
The Seward Highway Scenic Bi-way is one of the most challenging stretches of highway to navigate and manage in the United States. Maintaining safe passage for the public is a daunting task. With 127-miles of weather, earth and climate-thrashed asphalt along ever-changing waterways, mountain passes, forests and valleys, the people who work this road know each day can be an adventure.
The first 50-miles runs along the base of the stunning Chugach Mountains and the shore of Turnagain Arm. Along with beluga whales, moose, Dall sheep, waterfalls, bore tides and eagles, it’s not uncommon to see rocks the size of a basketball on the road. The remainder of the drive winds through the mountains, eventually landing you in Seward. In the winter snow often builds up on the slopes with sleet, ice and wind, creating a perfect recipe for an avalanche.
In 1952, during the first year of highway operations, an incident with two avalanches resulted in a car being destroyed and swept into Turnagain Arm and the death of one pedestrian by the second avalanche. Earlier records of avalanches describe an accident two-miles north of Girdwood in 1920 when six railroad workers were killed by a secondary avalanche that occurred while crews were removing debris from a previous snow slide.
Avalanches are epic events. Factors that increase the risk of avalanche danger include accumulation of new snow, rain, wind and extreme temperature swings…typical south central Alaskan winter weather. On steep peaks, the snow generally sheds before dangerous build up can occur. The slopes between 30 to 45 degrees are the most dangerous. Loose snow avalanches start at a specific point on the slope then, as they travel downward they widen and pick up size and speed “snow” engulfs and sets as hard as concrete. Slab avalanches are massive plates of bonded snow and ice that fracture off and race downhill. Those who have survived being caught in an avalanche report exceedingly grim experiences.
In 2000, when multiple avalanches seized the region, a railway employee with 21-years on the job was killed while clearing avalanche debris when a secondary slide at Bird Flats exploded down the “Five Finger’s Chute” and pushed him and his 35,000-pound D6 Caterpiller bulldozer 400-feet into Turnagain Arm. The bulldozer was demolished. Others narrowly escaped after rescue. Upon analysis of the path and debris, it was estimated that the avalanche crossed the highway at approximately 110-miles per hour. Girdwood residents and travelers trapped by the slides banded together for days of isolation and limited provisions.
Elsewhere, more recently in 2014 a series of slides (natural and triggered), on Richardson Highway covered the road and railway, and choked the Lowe River creating dangerous flood conditions that threatened the already-stranded residents and delayed crews from removing the snow. Valdez was cutoff for days.
During the season, the Alaska Department of Transportation monitors the known avalanche paths. When the conditions are ripe, they bring in the big guns, including a World War II vintage Howitzer cannon, to trigger slides. The trailer-mounted Howitzer uses a relatively small propellant charge to fire a 40-pound projectile at a steep angle of trajectory up to a distance of six miles. The crew is skilled at zeroing in on their target to mitigate the potential danger.
After artillery is used to cause a controlled avalanche, ADOT crews clear the road of massive amounts of snow, ice and debris, historically a very dangerous undertaking.
In 2014, ADOT acquired a “Daisy Bell,” a device mounted in a helicopter that uses a high-velocity cone of oxygen and hydrogen gas to loosen snow packs.
Avalanches aside, traffic accidents are by far the number-one cause of death on Seward Highway. It is important to have insurance as a driver to be covered in case anything like an accident was to happen on the road. Plus it is illegal not to. If using a vehicle like a truck or lorry is the main focus of your job, you should make sure you have the right wagon insurance to cover both you and your vehicle. Alaska is a wild, amazing place. The spectacular scenery on Turnagain Arm can be distracting. Don’t make the journey any more extreme by tailgating or speeding.
Public notification of avalanche work includes LED signs at Potter’s Marsh and Moose Pass on the Seward Highwa, and on the ADOT website. Call 511 or visit www.511.alaska.gov for current road and weather information, updates on avalanche control work, and to sign up for 511 e-mail/text alerts.