Quick Answer
Terrain types significantly influence evacuation speed, with difficult terrain causing evacuees to move at approximately 1-2 kilometers per hour.
Terrain Classification
Terrain classification is crucial in determining evacuation speed. The US Army defines four terrain categories: flat (0-10% slope), gentle (10-30% slope), steep (30-60% slope), and vertical (above 60% slope). Evacuees moving through flat terrain can maintain speeds of up to 4-5 kilometers per hour, while gentle slopes may reduce speed by 25%. Steep slopes can decrease speed by 50%, and vertical terrain often requires specialized equipment or assistance.
Evacuation Techniques
Evacuees should adjust their techniques according to terrain type. For example, in flat terrain, evacuees can use a 1-2 person stretcher or carry patients themselves. On gentle slopes, evacuees may use a 2-4 person stretcher or employ a “log carry” technique. Steep slopes often require a 4-6 person stretcher or a rope-based “Tyrolean traverse” technique. In vertical terrain, a rope-based rescue system may be necessary.
Estimated Evacuation Times
Estimated evacuation times vary depending on terrain and technique. For a single patient in flat terrain, evacuation can take around 30-60 minutes. In gentle terrain, evacuation times increase to 60-120 minutes. Steep terrain can increase evacuation times to 2-4 hours, while vertical terrain can require 4-6 hours or more, depending on the complexity of the rescue operation.
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