Progress of excavation works on Second track
Underground excavation is currently underway at 10 attack points, with around 350 metres of tunnels being excavated per week, and we are approaching 29 kilometres of main and service pipes excavated. A rough estimate of the excavated material for the whole project up to September 2023 is 2,000,000 m3.
The geological and geotechnical conditions of the excavation works are constantly changing and are only partially known in advance. The Osp Tunnel (T5-6) is currently the shortest tunnel currently being excavated on the Second track route at 513 metres. It is the only tunnel on the route where the conditions for excavation work are worse than expected, requiring more support elements (anchors). Tunnel Osp is one of the two tunnels originally planned, which have been merged into a single tunnel for stability reasons.
Preliminary investigations have also shown that approximately 100 minor and 10 major karst features will be identified. So far, 52 karst caves have been discovered and almost 80% of the tunnels have been excavated. The karst phenomena do not hinder tunnelling to a large extent and all the caves are being investigated and inventoried by karst experts.