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Avalanche expertise for cableways: Detecting hazards in good time

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The largest ski area expansion project in Switzerland is currently being realized between Andermatt and Sedrun, where 16 installations should modernize and connect the two small resorts. Mark Schaer, a civil engineer at SLF, joined the Project seven years ago. He used the avalanche-dynamics modelling software RAMMS to assess whether the planned installations and ski-slopes are at risk. He says: “In the section Gütsch-Oberalp­pass, three cableways and around fifteen kilometers of ski-slopes are planned. Initially, the cableway operators did not think that avalanches posed a serious threat in the area. Our evaluations have, however, shown that the avalanche problem here is complex.”

In this section area, Mark identified 120 avalanche-starting zones. The “Russengraben” was one of the tricky places because the top station of a cableway will be built close to it.  Mark calculated how strong the forces of avalanches would be after they have crossed the Russengraben (red arrow in the photo) and reach the station. “We had to take into consideration how snow-slides and snow-drifts can fill up the Russengraben and thus change the topography there.”

At six of the eight sites originally intended for cableway stations, the avalanche risk turned out to be so great that avalanche protection structures would not have been possible at reasonable cost. New locations therefore had to be found. Two installations had to be shortened by several hundred meters. As Mark says: “When planning a new ski area, it is important to involve an avalanche expert at an early stage in order to avoid delays and unnecessary costs. Certainly in the case of Andermatt-Sedrun, the cooperation has been worth it.” (Sara Niedermann, Diagonal 2/17)