Winter Highway Operations (2005)

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