Leica helps build longest rail tunnel

Leica helps build longest rail tunnel

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Heerbrugg, Switzerland: A new world record was created when the miners working on the Gotthard Base Tunnel in Switzerland shook hands after the breakthrough between the Sedrun and Faido access points. With this, the 57 km Gotthard Base Tunnel has become the longest rail tunnel in the world, according to Leica Geosystems. The surveying instruments used in the tunnel were supplied by the company.

With the help of high-performance total stations, digital levels and optical plummets from Leica Geosystems, the position of the “hole” was continuously checked to ensure that it was within the accuracy required by the client AlpTransit Gotthard AG – 10 cm transversely and 5 cm vertically over the whole 57 km length of the tunnel.

Adrian Ryf, Head of geomatics with AlpTransit Gotthard AG, set a world record of his own at Gotthard: in summer 2005, using 28 Leica Geosystems GPS systems simultaneously, the former lecturer at the Swiss Federal Institute of Technology (ETH Zürich) and his students carried out what was then the largest-ever surveying campaign for an engineering project. The aim was to check the permanent station network. It had never been surveyed using GPS, the company adds.

“With a construction time of almost 20 years in a tectonically active Alpine region, it was extremely important for the success of the project to check these permanent stations,” explained Adrian Ryf.

Leica Geosystems instruments are in use above ground as well as the Gotthard Base Tunnel which passes directly under three water reservoirs. “A tunnel always influences the water balance in the mountain. The loss in pressure due to the water extracted from the rock could result in the mountain literally collapsing,” explained Ivo Schätti. “To prevent this from occurring, we monitored the movements of the valley sides near the dam walls and in the areas leading up to them. High-precision total stations and Leica GeoMoS monitoring software were used to measure the movements. The instruments have been in use since 2000 and always performed perfectly,” said Ivo Schätti.

Source: Leica Geosystems