Innovative Solutions for the Construction of the Second Track Presented at the BCRRA 2026 International Conference

At the 12th International Conference on the Load-Carrying Capacity of Roads, Railways, and Airports (BCRRA 2026), 2TDK presented its experience and innovative solutions developed during the construction of the second Divača–Koper rail track. The conference, held every four years, is considered one of the most important professional gatherings in the field of transportation infrastructure.

In his presentation titled “Overcoming Karst Phenomena: A Major Challenge in Tunnel Construction,” Marko Brezigar, Director of 2TDK, discussed one of the most challenging aspects of building the new railway line. The route of Slovenia’s largest infrastructure project runs through an exceptionally challenging karst region, where contractors faced unpredictable underground phenomena during construction. As many as 99 karst phenomena were discovered during construction, and Brezigar paid special attention to the exceptionally large karst caves, which required the development of entirely new engineering solutions. In the largest karst cavities, approximately 100 meters below ground, four reinforced concrete arch bridges with spans ranging from 25 to 45 meters were constructed. Since the cavities could not be backfilled for environmental protection reasons, a technical solution had to be found to bridge the voids and ensure sufficient stability of the foundation soil. At the same time, this approach also preserved the natural underground water flows, which are vital for supplying the Slovenian coast with drinking water. Constructing the bridges in tunnels more than six kilometers long also presented an extraordinary logistical challenge. Since the structures will be permanently inaccessible once the work is completed, they were equipped with sensors to monitor any potential movements and settlements and to ensure long-term safety.