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Avalanche Hazard Reduction Using the Avalanche Guard: a Cache and Mortar Technology

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Avalanche Hazard Reduction Using the Avalanche Guard: a Cache and Mortar Technology AVALANCHE HAZARD REDUCTION USING THE AVALANCHE GUARD: A CACHE AND MORTAR TECHNOLOGY Robert Rice Jr.* University of California, Merced Steve Putnam Ralph Patterson Winter Alpine Engineering Corp, SLC, UT Utah Dept of Transportation, SLC, Utah Rand Decker Jamie Yount Northern Arizona University, Flagstaff, AZ WY Dept of Transportation, Jackson, WY Oswald Garber David Sly Outdoor Engineers, Inc., Golden CO CIL/Orion Inc, Victoria, BC Galen Richards Ted Wells WY Dept of Transportation, Jackson, WY WY Dept of Transportation, Rock Springs, WY Mark Bee Doppelmayr/CTEC, Golden, CO ABSTRACT: The Wyoming Department of Transportation (WYDOT) in Jackson, Wyoming installed and successfully operated the Avalanche Guard, an automated, remotely operable, fixed cache and mortar delivery system for avalanche control. The Avalanche Guard is installed on Teton Pass, Wyoming, and was operational during the 2003/04-winter season. This operational trial of the Avalanche Guard was the first successful attempt in North America (excluding Alaska) to install, cache live explosives, and operate remotely, via PC and RF Telemetry, with permitting from the Bureau of Alcohol, Tobacco, and Firearms (BATF), and the USDA Forest Service (USFS). Two stationary Avalanche Guards were installed on two separate avalanche paths, each with the capability of caching and delivering 20, 3.0 Kg charges, as well as, providing starting zone coverage of 300 meters. The objective was to demonstrate and evaluate a system that can improve all weather explosive delivery efficiency and cost effectiveness for State DOT avalanche control programs on the winter and alpine roads of the western United States. Experiences from the permitting, installation, and results from winter 2003/04 are presented. Keywords: avalanche control, avalanche hazard reduction, artificial avalanche release, transportation 1. INTRODUCTION control measures (explosive initiation of the avalanches) while the road is temporarily closed. Increased travel demand on the Operations of this style are carried out on winter/alpine roads of the Western USA has roadways in Alaska, California, Colorado, Idaho, resulted in a dramatic increase in the hazard to Montana, Nevada, Utah, Washington, and motorist and maintenance section personnel from Wyoming, as well as in Canada and Europe. snow avalanches. These encounters are often However, growth in overall risk to motorists and disastrous. maintenance section personnel is out-pacing our Presently, the state of practice for ability to adapt this present method of operation to managing avalanche hazards on the winter and meet safety objectives. alpine roads of the western United States is Typically, the scale of the problem is avalanche hazard forecasting, coupled with active largest in States with mountains and people; __________________________ California and Washington. By virtue of pure spatial scale alone, Alaska also has a significant * Corresponding author address: Robert Rice and expensive avalanche problem on roadways. Jr., College of Engineering, UC Merced, P.O. Colorado and Utah’s problems are of similar Box 2039, Merced, CA 95344, (P) 209/724- scale. Idaho, Montana, Nevada, and Wyoming 4397, (fax) 209/724-4459 each maintain modest State programs in email: [email protected]. avalanche hazard management. 688 In western Wyoming, as a consequence Teton Pass and Hoback Canyon are challenged of the rapid urbanization of the greater Jackson, by the need to deliver avalanche initiating WY area, the hazard to motorists and Wyoming explosive charges into the snowpack of avalanche Department of Transportation (WYDOT) highway starting zones, often well above the highway. maintenance personnel from avalanche activity in These explosive delivery systems include military Teton Pass on US Route (USR) 22 has increased. weapons, compressed air launchers, helicopter In addition to being the primary regional trunk road bombing, fixed gas/air exploders, and charges into and out of Jackson, Wyoming from Idaho and delivered by over-the-snow ground crews. Each points west, USR 22 is the principal route for east- of these explosive delivery systems has distinct west commuter traffic and commercial traffic in advantages and disadvantages. The outlook for western Wyoming. Similarly, USR 189 which ammunition supplies for the military weapons is passes through Hoback Canyon, south of the not assured. Compressed air launchers have Jackson area is heavily used both by commuter limited range and limited low visibility operating and commercial traffic into and out of the Jackson limits. Their cost-per-shot is relatively high. area (Figure 1) to points north and east in the Big Helicopter delivery of explosives is not an all- Horn basin and points south, including access to I- weather activity. More often than not, it is not 80. possible to use helicopters at the precise time State DOT avalanche hazard management programs, including WYDOT’s on Figure 1. Jackson Hole area map showing the highway routes in and out of the Jackson, Wyoming. 689 when explosive initiation of avalanches is most igniter as the charge is propelled out of the probable and desirable. Fix gas exploders can be magazine. The explosive charge reaches its operated in all-weather situations. However, their target and awaits the detonation of the blasting explosive “foot-print” is limited to an area cap and hence the explosive charge. The immediately adjacent to the exploder and hence charge delivered to the starting zone is a every potential explosive shot point needs its own Composition B explosion, or Brissance, which exploder. Manual delivery of explosives charges describes the combination of a High velocity is precluded by both the distances above the m highway that are involved and the fact that during (8,600 ) high gas volume and vacuum effect times when avalanche explosive control is s needed, it is not sound advice to be traveling over- created from the explosion. the-snow in the same terrain. In addition, other novel delivery devices are in operation or being Advantages: investigated (Gubler and Wyssen, 2002). The objective of this investigation was to • Minimal personnel, set up and clean up demonstrate, evaluate, and operationally on day of mission. integrate the Avalanche Guard, an avalanche • Loading can occur on fair weather days, control delivery system that can improve all- rather than during extreme conditions or weather explosive delivery, efficiency, and cost in a hurry up situation. effectiveness for the Wyoming Department of • No air, electrical, or communications to Transportation (WYDOT) avalanche control remote units. program on Teton Pass in WY. In addition, the • Charge is relatively bio-degradable. objective was to investigate if the Avalanche • Low cost per shot. Guard was a reliable, robust, and operational • Mission can be fired remote from site, viable alternative (or additional) method for insuring safety of personnel. delivering avalanche control explosives to • Multiple targets from one site, in relation avalanche starting zones in all-weather conditions to direction and range. for State DOT avalanche control programs on the • Unit is extremely weatherproof and winter alpine roads of the western U.S. During the rugged and meets BATF standards. 2003-2004 winter season, the Avalanche Guard • Electronics and communications are was deployed operationally and evaluated in based on industry standards. WYDOT District 3 on Teton Pass. • Consistency of shot placement. The specific tasks associated with this • Unit can be relocated. investigation included: i) site planning for both • Operation in adverse weather or Teton Pass and Hoback Canyon, ii) Avalanche darkness is possible. Guard installation, training test firing, and • Small foundations => minimal footprint. operational loading, and integration, and iii) • No shrapnel. evaluation of system performance and • operational integration, as well as lessons Adjustable if necessary after experience learned. with installations. • Only one mechanical moving part (door). 2. HOW THE AVALANCHE GUARD WORKS Disadvantages: Prior to the operational avalanche season the magazine(s) are loaded with ten 3 kg • Prior planning required for location. charges with a black powder propellant capable • Foundation is immobile once placed. of launching a charge 230 meters (Figure 2). • Range is limited to 230 meters. The explosive charge is launched from the • Use of explosives does require some magazine via RF communication from a PC expertise and training. operated by authorized personnel. Instructions • Access to site required for reloading (or are received at the remote site and the specified by long line on a helicopter). explosive charge is launched. Upon launch a fuse is ignited by a mechanical ignition of the 690 Remote Fire Detonator Black Powder End Caps Mildet Detonators Fuse Holders 10 cm Dead Air 3 kg Composition B Recco chip Filler Launching Cup Pullwire Lighters attached to Frame Mildet Fuse Fuse Tie Down with a Hook and Lanyard For charges larger than 3 kg, reduce Detonation Confirmation the filler space accordingly Figure 2. Schematic of the Avalanche Guard Charge Twins avalanche path (Figure 4) consists 3. INSTALLATION OF THE AVALANCHE of two avalanche paths, Upper and Lower Twin. GUARD Upper Twin is characterized by a return interval of 4 per year, an open bowl with a channelized track, 3.1 Site Selection varying in elevation from 2,866 meters to 2,927 meters with a southern aspect, and a slope angle Glory Bowl and Twins avalanche path of 33-35 degrees. Estimated yearly snowfall is located on USR 22, Teton Pass, were selected for 1,000 centimeters. Traditionally, avalanche installation of the Avalanche Guard. Glory Bowl mitigation efforts deploy artillery, 1 Gaz Ex (Figure 3) is characterized by a return interval of 3 exploder, and heli-bombing. Lower Twin is + avalanches per year, an open bowl with a characterized by a return interval of 4 per year, an channelized track, varying in elevation from 2,800 open bowl with a channelized track, varying in meters to 3,020 meters with an aspect of elevation from 2,896 meters to 2,900 meters with southeast to southwest, and a slope angle of 30- an aspect of southeast to southwest, and a slope 32 degrees.
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