However, an unexpectedly high proportion of anhydrite in the rock caused increasing damage to the roadway, pipelines, and anchors used to stabilize the roadway. Although the tunnel only entered service in 2005, comprehensive renovation was already necessary by 2019. The tunnel was fitted with elastic material and subsequently re-concreted.
On behalf of the Federal Roads Office (FEDRO), surveying work in the tunnel was carried out with SIGN partner HMQ AG. Additionally, the construction site was monitored using GeoMonitoring, ensuring a high level of safety on site. The monitoring proved extremely important, especially during the construction phase in fall 2019: After excavation of the tunnel floor, displacements were detected on the wall and intermediate ceiling, which were stopped through safety measures. This enabled the construction work to be implemented efficiently and safely.
