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identified avalanche risks, the hazard is assessed by identifying threatened human geographic features such as roads, ski-hills, and buildings. Avalanche control programs address the avalanche hazard by formulating prevention and mitigation plans, which are then executed during the winter season. The prevention and mitigation plans combine extensive snow pack observation with three major groups of interventions: active, passive and social - sometimes more narrowly defined as "explosive", "structural", and "awareness" according to the most prevalent technique used in each. Avalanche control techniques either directly intervene in the evolution of the snow pack, or lessen the effect of an avalanche once it has occurred. For the event of human involvement, avalanche control organizations develop and train exhaustive response and recovery plans.
106:. These two mechanical interventions can only be safely done as the snow is deposited and before it develops any instabilities. In terrain that can only be sporadically accessed, or in a highly developed snow pack that is too deep for boot packing, ski stabilization techniques are used. The first technique of ski stabilizing is a method of entering a slope called ski cutting. In this method a skier attempts to trigger a small avalanche by breaking the tensile support of the upper snow pack through a quick traverse along the top of the slope, the skier can be belayed on a rope to further protect them from being caught in an avalanche. A snow pack can then be further settled out, or stabilized, by further down slope ski traffic through it. Finally knotted cord can be used to saw through the roots of
580:
terrain. Surveys of avalanche accidents have observed that most avalanches that involve people are caused by people, and of those victims many were unaware of the risk of avalanche occurrence. To address this observation, introductory awareness and education programs provide instruction in the avoidance of hazardous avalanche involvement through the recognition of avalanche terrain, the observation of snow pack instabilities, and the identification of human activities that cause avalanches. Avalanche control organizations also publicly disseminate forecasts, bulletins, warnings, and reports of avalanche activity to assist communities of avalanche terrain users.
98:
for entrainment in an avalanche; this can be accomplished either by triggering smaller less hazardous avalanches, or by directly influencing the structure of the layering of the snow pack. Active avalanche control can be broadly classified into either mechanical or explosive methods. Mechanical methods are typically used in either remote terrain, smaller terrain, or less hazardous terrain; while explosive methods are used in accessible large high hazard terrain, or terrain with industrial, commercial recreational, urbanized, and transportation usage.
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the snow cover on the terrain surface. Breaking-away of avalanches is thus prevented at the starting zone, while occurring snow movements are restricted to the extent that they remain harmless. The forces resulting from the snow pressure are absorbed by the snow nets and carried off over the swivel posts and anchor ropes into the anchor points.
606:
Recreational response to avalanches involves the rapid formation of an ad hoc search and rescue team. The ad hoc search and rescue teams rely on all the participants having prepared for a potential avalanche by carrying the correct search and rescue equipment, and undergoing the appropriate training.
597:
Professional responses to avalanches are targeted at avalanches involving the general unprepared public. When avalanches are forecast to occur, avalanche terrain to which the general unprepared public is exposed will be closed, and after the avalanches have occurred the area is cleared of debris, and
158:. In balancing the hazard to personnel with the effectiveness of the deployment method at accessing and triggering avalanche terrain, each method has its drawbacks and advantages. Among the newest methods, strategically placed remote controlled installations that generate an air blast by detonating a
97:
Active techniques reduce the risk of an avalanche occurring by promoting the stabilization and settlement of the snow pack through three forms of intervention: disrupting weak layers in the snow pack, increasing the uniformity of the snow pack, and lessening the amount of snow available in snow pack
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Avalanche barriers: The main part of the avalanche barriers is based on a high tensile strength steel wire mesh, extending across the slope and reaching to the surface of the snow. The supporting effect created by the retaining surface prevents possible creeping within the snow cover and sliding of
101:
In the smallest terrain features the simplest method of avalanche control that disrupts weak snow layers by directly walking through them, a technique referred to as boot packing. For larger features this method can extended by mechanized redistribution of snow using large tracked vehicles called
40:
pose to human life, activity, and property. Avalanche control begins with a risk assessment conducted by surveying for potential avalanche terrain by identifying geographic features such as vegetation patterns, drainages, and seasonal snow distribution that are indicative of avalanches. From the
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of human avalanche involvement by modifying the behavior of people, so that their use of avalanche terrain is adapted to prevent their involvement in avalanches. Avalanche control organizations accomplish this by targeting awareness and education programs at communities that frequent avalanche
59:
evolution under the prevailing meteorological conditions. In contrast to heavily used avalanche terrain where forecasting is the goal of snow observation, in remote terrain, or terrain that is infrequently visited, snow pack observation elucidates the immediate instabilities of the snow pack.
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Snow pack observation studies the layering and distribution of the snow to estimate the instabilities of the snow pack and thus the risk of an avalanche occurring in a particular terrain feature. In areas of heavy human use the snow pack is monitored throughout the winter season to assess its
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Avalanche control organizations plan for, and respond to, avalanches. Typical responses span from clearing transportation corridors of avalanche debris, to repairing industrial and recreational facilities, to search, rescue, and recovery. To improve the outcome of human avalanche involvement
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above the snow pack in an avalanche starting zone, offer fast and effective response to avalanche control decisions while minimizing the risk to avalanche control personnel; a feature especially important for avalanche control in transportation corridors. For example, the
Avalanche Towers
163:(Sprengmast) Austria, and Norway use solar powered launchers to deploy charges from a magazine containing 12 radio controlled charges. The magazines can be transported, loaded, and removed from the towers by helicopter, without the need for a flight assistant, or on site personnel.
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Explosive control has proved to be effective in areas with easy access to avalanche starting areas and where minor avalanches can be tolerated. It is mostly unacceptable, however, in areas with human residence and where there is even a small probability of a larger avalanche.
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cables or straps held by steel poles, optionally supplied with compression anchors downhill. They are installed in the upper parts of potential avalanche paths to prevent snow from starting to slide into an avalanche, or to retard the slide.
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Both types of avalanche dams are usually placed in the run-out zone of the avalanche and in the flatter parts of the avalanche path. In other parts of the avalanche they are ineffective because they may be easily overrun or overfilled.
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repaired. When unexpected avalanches occur that involve the general unprepared public, avalanche control organizations respond with large professionally organized search teams involving probe lines, and trained search and rescue dogs.
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Explosive techniques involve the artificial triggering of smaller less destructive avalanches, by detonating charges either above or on the snow surface. The explosives may be deployed by manually hand tossing and lowering, by
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Prevention and mitigation begins with observing the snow pack to forecast the risk of avalanche occurrence. The forecast risk then determines the necessary interventions to reduce the hazard posed by an avalanche.
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Permanent techniques slow, stop, divert, or prevent snow from moving; either completely or to enough of an extent that the destructive forces are significantly lessened. Permanent techniques involve constructing
409:, milepost 57.7); it was removed in 2014 in preparation for the construction of bridges to replace it. The 500-foot (150 m) concrete structure covered two lanes on a curve and was constructed in 1950 for
110:, causing the cornice to drop onto the snow pack of the slope below. This has the combined effect of reducing the objective hazard posed by the cornice, and providing a large impact force on the snow pack.
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Snow deflection structures used to deflect and confine the moving snow within the avalanche track. They should not deflect the avalanche sharply, because in the latter case they may be easily overrun by
313:. These structures can be fully enclosed, like an artificial tunnel, or consist of lattice-like elements. They are typically of robust construction considering the environments they must survive in.
453:, but they act differently. Snow fences are built vertically and accumulate snow on their downwind side, while snow bridges are slanted or horizontal and hold snow on their top side.
413:, then one lane in each direction; it marked the first time precast construction was used for a highway structure in a mountainous area and was the last remaining snow shed on an
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Snow protection is particularly important when routes cross avalanche "chutes", which are natural ravines or other formations that direct or concentrate avalanches.
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is a type of rigid snow-supporting structure for avalanche control or to maintain passage in areas where snow removal becomes almost impossible. They can be made of
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Snow retardation structures (e.g. snow breakers), mostly used in small-slope parts of the avalanche track, to enhance the natural retardation
848:
Jaedicke, Christian; Naaim-Bouvet, Florence; Granig, Matthias (2004) "Wind-tunnel study of snow-drift around avalanche defense structures",
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are used to temporarily protect bivouacking climbers and skiers by providing them with breathing space in the event of burial by avalanches.
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avalanche control organizations offer training and education to both professionals and recreational amateurs in avalanche preparedness.
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had a complete rail yard under a roof on Donner Pass. They are also found on especially hazardous stretches of roadway as well. The
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Snow avalanche nets have the following advantages compared to rigid supporting structures (snow fences, snow racks, snow sheds):
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Architectural streamlining and wedge shaping buildings, such as those found in the historic high mountain villages of the Alps.
249:— forests serve all the functions of artificial avalanche defenses: retention, redistribution, retardation and catchment.
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Snow retention structures (snow racks, avalanche snow bridges, snow nets), used in the upper path of probable avalanche paths
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Snow bridges are fastened to the slope on the upslope side by tension anchors and on the downslope by compression anchors.
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475:) are a type of avalanche control structure used for protection of inhabited areas, roads, power lines, etc., from
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A single intervention may fulfill the needs of multiple classes of purpose, for example, avalanche dams,
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Direct protection of important objects and structures, e.g., by snow sheds (avalanche sheds) or
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mountain railways, where tracks are covered with miles of shedding. Although unused today, the
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Snow sheds or avalanche galleries are a common sight on railroads in mountain areas, such as
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Avalanche nets have some drawbacks, as they are more difficult to anchor in loose ground.
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has several snow sheds covering both directions of travel to cope with the heavy snow.
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The design of avalanche protection dams. Recent practical and theoretical developments
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are used for deflection, retardation, and catchment. Other passive methods include:
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506:) are flexible snow supporting structures for avalanche control, constructed of
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Nets are less damaged by rocks because their flexible structure dissipates the
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http://edoc.hu-berlin.de/kunsttexte/2010-3/falser-michael-1/PDF/falser.pdf
714:"New bridges get green light to replace snowshed east of Snoqualmie Pass"
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To mitigate the hazard of avalanches, social interventions reduce the
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rigid structures are more prone to damage in unstable terrains (with
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747:. Washington State Department of Transportation. April 16, 2016.
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827:"Protective barrier, in particular for mountainous places"
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Snow redistribution structures (wind baffles, snow fences)
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688:"Avalanche and torrent control in the Spanish Pyrenees"
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Forest and structures to protect against avalanches.
479:. The two major types are deflection and catchment
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devices (used to increase snow retention on roofs).
188:and modifying terrain for purposes classified as:
712:McFadden, Meagan; Smith, Jason (March 13, 2013).
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255:, as well as recessed, dug out, and snow walled
374:had a snow shed midway along the east shore of
279:Trains passing in an avalanche gallery on the
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22:An avalanche snow bridge near a ski-resort in
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772:"The I-90 Snowshed Retires After 64 Years!"
839:"Snow-supporting structures in permafrost"
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692:National Forests Organization of Spain
651:"Mitigation and Land Use - Avalanches"
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624:, control of a similar disaster type
525:better blending into the environment
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741:"I-90 Snowshed Removal Time Lapse"
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770:Derrey, Summer (March 18, 2014).
670:Photographs of avalanche defences
449:, looks superficially similar to
694:. Patrimonio Forestal del Estado
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82:(3,600 m or 11,800 ft)
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751:from the original on 2021-12-12
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861:In: kunsttexte 3/2010, unter:
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720:. Department of Transportation
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500:snow avalanche protection nets
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676:corporate document repository
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551:) and in conditions of heavy
36:activities reduce the hazard
879:United States Forest Service
660:, Colorado Geological Survey
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656:September 17, 2006, at the
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54:Observation and forecasting
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71:Avalanche blasting in the
875:National Avalanche Center
593:Professional preparedness
473:avalanche protection dams
215:Snow catchment structures
142:from a helicopter, or by
125:for avalanche control at
45:Prevention and mitigation
787:(dead link 8 March 2019)
730:(dead link 8 March 2019)
522:considerably lower costs
337:Central Pacific Railroad
171:Permanent interventions
899:Nonbuilding structures
825:of falling rocks, see
776:WSDOTBlog.BlogSpot.com
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584:Response and recovery
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853:, vol. 38, p.325-330
851:Things of Glaciology
829:, patent description
797:"Steel snow bridges"
622:Landslide mitigation
617:Cellular confinement
602:Amateur preparedness
567:Social interventions
341:Trans-Canada Highway
307:prestressed concrete
131:Inyo National Forest
63:Active interventions
718:State of Washington
528:easier installation
469:anti-avalanche dams
397:47.355°N 121.3658°W
393: /
121:team using a 105mm
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222:(in mining areas).
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160:fuel-air explosive
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443:avalanche barrier
402:47.355; -121.3658
331:, or many of the
299:avalanche gallery
245:, up the natural
34:avalanche defense
30:Avalanche control
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894:Avalanche safety
857:Michael Falser:
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123:recoilless rifle
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904:Dams by type
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779:. Retrieved
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722:. Retrieved
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533:earthquakes
451:snow fences
439:snow bridge
431:Switzerland
421:Snow bridge
400: /
388:121°21′57″W
325:Donner Pass
321:Marias Pass
309:frames, or
888:Categories
698:2016-12-01
629:References
577:prevalence
549:soil creep
547:-mediated
545:permafrost
537:landslides
477:avalanches
415:Interstate
385:47°21′18″N
364:Washington
345:Revelstoke
287:See also:
253:snow caves
200:Snow guard
186:structures
76:ski resort
38:avalanches
24:Vorarlberg
573:incidence
504:snow nets
417:highway.
368:northwest
295:snow shed
289:Rock shed
271:Snow shed
257:quinzhees
247:tree line
781:June 21,
755:June 21,
749:Archived
724:June 21,
654:Archived
611:See also
557:mudflows
553:rainfall
541:rockfall
358:East of
343:between
236:terraces
148:howitzer
144:shelling
108:cornices
877:of the
745:YouTube
366:in the
327:in the
228:ditches
156:air gun
146:with a
140:bombing
129:in the
349:Golden
311:timber
234:, and
80:Tignes
73:French
512:nylon
508:steel
445:, or
333:Swiss
303:steel
209:snow.
154:, or
117:U.S.
91:Gazex
783:2017
757:2017
726:2017
575:and
555:and
481:dams
347:and
323:and
259:and
674:FAO
510:or
362:in
351:in
297:or
78:of
32:or
890::
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