The 1,909m long Magnacun tunnel between Guarda and Ardez, built in 1913, is located at an altitude of 1,435m and is situated in a geologically very challenging zone.

  • 250 Meter Maintained
  • 13 Million CHF
The valley flank of Piz Cotschen moves about 10 millimeters per year at tunnel level and therefore had to be rehabilitated.

The project - executed by ARGE IMA - comprised the complete demolition and new construction of the 250m long portal zone with the aid of a pipe umbrella jacking system during a total closure.

The interior lining, consisting of waterproofing sheeting and shotcrete interior vaulting, was carried out during night closure breaks while the railroad was in operation.

In order to preserve the UNESCO World Heritage Site, the new Guarda side portal was built of local natural quarry stone. 
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