Gotschna Tunnel


The Sunniberg bridge and the 4,207-meter-long single-tube Gotschna tunnel directly adjacent to it had already made it possible to bypass the community of Klosters for 14 years. But an unexpectedly high proportion of anhydrite in the rock caused more and more damage to the roadway, the pipes, and the anchorages that serve to stabilize the roadway. Although the tunnel was only put into operation in 2005, comprehensive rehabilitation was already necessary for 2019. The tunnel was equipped with an elastic material and then concreted anew.

On behalf of the Federal Roads Office (FEDRO), SIGN’s partner HMQ AG carried out surveys in the tunnel. In addition, the construction site was monitored by means of geomonitoring, thus ensuring a high level of safety on the construction site. Monitoring proved to be extremely important, especially during the construction phase in the fall of 2019: After the tunnel floor had been removed, displacements were discovered on the parament and on the intermediate ceiling, which could be stopped by means of securing measures. Thus, the structural interventions could be implemented efficiently and safely.