For the construction of the Untersberg cable car in 1961, the foundations of pillar 1 had to be tied back against the steep rock flank of the East face of the mountain with nine prestressed anchors. Since then, regular monitoring and two lift off tests have been carried out in order to verify the actual working load of the tie-backs. In 2012 a risk analysis has been performed to assess the consequences of anchor failures and it was finally decided to install new tie-backs in 2014. The refurbishment project has successfully been carried out and focused on a very short business interruption and minimal material consumption due to the exposed location of the pillar. The article presents the results of the long time monitoring and the risk analysis for the old tie-backs, as well as the refurbishment project and the challenges during construction.
The Untersberg cable car is located about 10 km south of Salzburg and has been built from 1958 to 1961. It is operated by a two-cable system and runs in shuttle-traffic. From a technical point of view, the cable car has some outstanding characteristics in comparison to other cable cars within the Alps: Exceptionally large difference in altitude of 1,320 m, largest distance from the ground 286 m, and an enormously long free-hanging span of 1,548 km between the valley station and pillar 1 (Untersbergbahn 2015).