Avalanche Avoidance
Due to the complexity of the subject, winter travelling in the backcountry (off-piste) is never 100% safe. Good avalanche safety is a continuous
process, including route selection and examination of the snowpack, weather conditions, and human factors. Several well-known good habits can also
minimize the risk. If local authorities issue avalanche risk reports, they should be considered and all warnings heeded. Never follow in the tracks
of others without your own evaluations; snow conditions are almost certain to have changed since they were made. Observe the terrain and note obvious
avalanche paths where vegetation is missing or damaged, where there are few surface anchors, and below cornices or ice formations. Avoid traveling
below others who might trigger an avalanche.
There are several ways to prevent avalanches and lessen their power and destruction. They are employed in areas where avalanches pose a significant
threat to people, such as ski resorts and mountain towns, roads and railways. Explosives are used extensively to prevent avalanches, especially at
ski resorts where other methods are often impractical. Explosive charges are used to trigger small avalanches before enough snow can build up to cause
a large avalanche. Snow fences and light walls can be used to direct the placement of snow. Snow builds up around the fence, especially the side that
faces the prevailing winds. Downwind of the fence, snow buildup is lessened. This is caused by the loss of snow at the fence that would have been
deposited and the pickup of the snow that is already there by the wind, which was depleted of snow at the fence. When there is a sufficient density
of trees, they can greatly reduce the strength of avalanches. They hold snow in place and when there is an avalanche, the impact of the snow against
the trees slows it down. Trees can either be planted or they can be conserved, such as in the building of a ski resort, to reduce the strength of
avalanches..
Avalanche Control
Artificial barriers can be very effective in reducing avalanche damage. There are several types. One kind of barrier (snow net) uses a net strung
between poles that are anchored by guy wires in addition to their foundations. These barriers are similar to those used for rockslides. Another
type of barrier is a rigid fence like structure (snow fence) and may be constructed of steel, wood or pre-stressed concrete. They usually have gaps
between the beams and are built perpendicular to the slope, with reinforcing beams on the downhill side. Rigid barriers are often considered
unsightly, especially when many rows must be built. They are also expensive and vulnerable to damage from falling rocks in the warmer months.
Finally, there are barriers that stop or deflect avalanches with their weight and strength. These barriers are made out of concrete, rocks or
earth. They are usually placed right above the structure, road or railway that they are trying to protect, although they can also be used to
channel avalanches into other barriers. Occasionally, earth mounds are placed in the avalanche's path to slow it down.