Item: SNOW CONVEYOR BELT – SUMMARY AND UPDATES ON THE MOST LIFE-SAVING AVALANCHE RESCUE EXCAVATION STRATEGY
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Title: SNOW CONVEYOR BELT – SUMMARY AND UPDATES ON THE MOST LIFE-SAVING AVALANCHE RESCUE EXCAVATION STRATEGY
Proceedings: International Snow Science Workshop Proceedings 2023, Bend, Oregon
Authors:
- Manuel Genswein [ MountainSafety.info ]
- MountainSafety.info Workgroup for Avalanche Rescue [ MountainSafety.info ]
Date: 2023-10-08
Abstract: The snow conveyor belt excavation strategy was developed in 2006 and has since been updated and fine-tuned in incremental steps. Its development started as an international collaboration, but the team creativity, multiplied intelligence and user group as well as snowpack climate representation provided by the MountainSafety.info Workgroup for Avalanche Rescue covering 27 nations finally landed on a strategy resulting in the fastest possible airway access times, and therefore highest possible survival chances for any imaginable situation in companion and organized avalanche rescue. The unmatched level of versatility of the strategy is founded in the practical robustness of rules of thumb, which allow the rescuers to determine the required lengths of the snow conveyor belt based on burial depth and inclination of the burial site. One rescuer is required to cover each meter of length in the snow conveyor belt. In case the number of rescuers is insufficient, it remains necessary to respect the required length of the snow conveyor belt, thus the rescuers will start one meter below the probe for each missing rescuer in the equation. Without shortage of resources, always start digging at the probe. Starting below the probe systematically leads to a significant increase of airway access time and shall be avoided – unless an insufficient number of rescuers leave no other option. The excavation performance reference database of the snow conveyor belt strategy includes 391 results from 5 countries and allows MountainSafety.info to analyze and optimize the strategy based on user group, activity and gender. The quantitative analysis of the influence of the starting point of the excavation effort has been contributed by the Italian MSi workgroup members under the umbrella of the Italian Alpine Club. The most recent updates of the strategy include: (1) the detailed definition of the procedure «Snow Conveyor Belt With Limited Resources»; (2) the extension of the segment length covered by one rescuer to 1m; (3) securing appropriate distances between rescuers as part of each rotation; (4) the reference width of the segment is carved into the snow by each rescuer in the form of a semi-circle, leading to an optimal balance between the size of the workspace required for efficient shoveling and the resulting excavation volume. Reproducible, quantitative field test results in excavation strategies require strict protocols ensuring an adequate user-group specific training level, fatigue bias prevention by minimum rest duration between trials and the number of trials per day per rescuer as well as debris hardness correction factors, leading to standardized debris properties. In hard debris, rescuers remove a median depth of 13.20cm/min; in soft debris, a median depth of 25.32cm/min is removed. These values are achieved when applying the conveyor belt with the appropriate number of rescuers. With limited resources, the excavation performance decreases, but still allows a single rescuer to excavate a buried subject in the mean burial depth in ski touring of 1.5m within the critical first 18min of burial duration based on the "Snow Conveyor Belt With Limited Resources" protocol.
Object ID: ISSW2023_P3.08.pdf
Language of Article: English
Presenter(s): Manuel Genswein
Keywords: avalanche rescue, excavation, conveyor belt, survival chance optimization
Page Number(s): 1314 - 1318
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