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22 CHAPTER FIVE SPECIAL CONSIDERATIONS BLIZZARDS AND DISASTERS propane and oxygen and fired by remote control. GazEx was the only option for on-site systems; however, notable recent Each decade winter storms of catastrophic proportion occur advancements include the remote "Avalanche Blaster Cache" in North America. Fifty percent of the responding agencies and mortar technology being evaluated by the Wyoming DOT, (10 of 20) do not have a strategy to address winter storms along with the AvalHex recently introduced from France. beyond their capacities. Agencies that have disaster plans There are several current highway avalanche research proj- include Alberta Transportation, Connecticut DOT, City of ects supported by FHWA and TRB including Edmonton, Maryland DOT, Missouri DOT, Ministre des Transports du Qubec, New Brunswick DOT, Nebraska DOT, Optimization of the Avalauncher avalanche control Nevada DOT, and Saskatchewan DOT. Alberta, Nevada, and projectile, Saskatchewan all report improvements owing to experience, Evaluation of remote control equipment for avalanche events, and advancements in technology to such plans over clean-up, the surveyed 10 years. Infra-sonic monitoring of avalanche activity, and Wind drift disrupters. SNOW AVALANCHE Seven of the states and provinces operate routes subject to DESIGN AND CONSTRUCTION snow avalanche hazards. Idaho, Montana, and Oregon use temporary, passive methods including stability monitoring, Edmonton, Manitoba, Minnesota, Montana, New Brunswick, avalanche forecasting, warning, and closure. Alberta, Califor- Nebraska, and Oregon responded that they suggested changes nia, Nevada, and Washington all use active methods in the to highway design in attempts to reduce winter maintenance form of forecasting, explosive testing, and stabilization. This costs. Nevada documented maintenance considerations to be is not a complete list of provinces and states with highway included in the design of the I-580 freeway extension between avalanche problems. Several that did not respond to the survey Reno and Carson City. The design recommendations included: are also known to experience and manage avalanche hazards. Incorporation of divided alignments, Very little change has occurred in the manner and methods Non-use of undivided alignments with vertical separation, (forecasting, closure, use of explosives) of highway avalanche Wide shoulders and ditches, control in recent years; however, costs for control efforts have Sound wall use only with sufficient snow storage area been steadily rising. Faced with stockpile shortages and other (6 m minimum) and no shadowing of the roadway, problems related to the once commonly used recoilless rifles, Design of standard detail for installation of snow poles different surplus military weapons have been introduced such in proposed barriers, as the M-101 105mm howitzer and WSDOT's tank at Steven's Wide medians (15 m minimum) with minimal use of Pass. Explosive availability and increased regulation have also barriers, affected avalanche control program costs. Caltrans cited the Fills to be 0.74 to 1 m above existing grade (i.e., above improvement of avalanche control equipment, such as instal- the surrounding snow surface throughout a "design win- lation of GazEx systems. GazEx is a permanently mounted ter"), and system of an exploder tube that is filled with a mixture of Use of snow fence.