Glaciological Investigations for the Construction of a Chair Lift on a Glacier

Assemblage of the steel foundation for a mast on the Oberer Theodulgletscher (click to enlarge)

A mast of the chair lift and it's fondation fixed into the glacier (click to enlarge)

On the Oberer Theodulgletscher at Zermatt (Valais, Switzerland) a ski lift had been in operation for many years. Such an installation requires masts, which are mounted on the glacier surface. Recently, Zermatt Mountain Transport Company (Zermatt Bergbahnen Ltd.) replaced the ski lift with a chair lift in order to improve its transportation capacity. The Furggsattel glacier chair lift is the first one built on a Swiss glacier and is Europe's longest glacier chair lift, with 12 of the 18 masts standing on the glacier ice. The supports of the glacier chair lift were designed to be mobile in order to compensate for the movement of the glacier surface. The construction of the supports allows for a displacement of 75 cm on the steel foundations. However, the entire mast construction needs to be readjusted by an excavator once or twice a year. The chair lift was completed in November 2003 and is now in operation.

The glaciological consequences of the high load (90 tons) exerted by each mast on the glacier had to be analyzed. As a result of detailed investigations of the loading of the glacier surface with respect to the mast's foundation, it was concluded that masts could only be installed at locations without crevasses. In addition, as a result of the viscous ice deformation and ice melting due to pressure underneath the foundation, a maximum annual sink rate of 2 m/year was set by the construction company.

Finally, the authorities asked for a detailed monitoring program of the mast's movement and glacier changes.