ABSTRACT
The Koper-Divača link is a bottleneck on the core TEN-T network, impeding cargo transport from emerging port of Koper to their customers in the middle European countries. Karst edge with world famous natural phenomena presents the biggest obstacle for implementing a new railway line. Climbing more than 400 m in a short distance means that most of the track is pushed underground. The ground water table in karstic features can oscillate up to 120 m above tunnel level and due to environmental reasons the ground flow should not be changed. Therefore an undrained concept is foreseen. Many different challenges were addressed during the investigation and design phase and will be reflected during the construction, especially karstic ground with high water table and/or filled with soft material and others like squeezing in over thrusted zones, excavation with low cover below highway and other infrastructure, underground excavation along steep slopes, etc.
