STA, 12 July 2022 - After digging the first good kilometre of what will be an almost 7-kilometre tunnel on the new Divača-Koper railway track, workers have already stumbled on 21 karst caves, including some with one metre long stalactites. Railway constructor 2TDK says this will not delay the construction of what will be the longest tunnel of the track.
"Generally, in the construction of the Lokev tunnel we find a karst cave every 50 metres," 2TDK said in a press release, noting that they had not yet reached the area where most karst caves are expected.
When a cave is discovered, it is explored, measured and documented by experts from the Karst Research Institute (Inštitut za raziskovanje krasa), who then propose measures that need to be endorsed by the Nova Gorica branch of the Institute for Nature Conservation.
"Some (caves) are big enough to be accessed without climbing or any other technical gear, and the longest stalactites are one metre long. Based on geophysical measurements, we expect to find about ten large and some 100 small caves during the construction of the railway track and we'll try to preserve as many of them as possible," the company said.
The largest cave discovered so far has a six-metre long entrance and 69 metres of passages. It features stalactites and some stalagmites, and is rich in mineral deposits.
The cave discoveries have so far not affected the construction plan, but a potential discovery of a large cave could suspend the construction for a while. "Engineers are most concerned that they will stumble on a karst cave that would require the construction of a bridge," the company said.
The new railway linking the port town of Koper with the Divača railway junction is to feature seven tunnels. The first one was broken through a month ago.
Slated for completion in 2025, with the track due to open the following year, the whole railway project is valued at little below one billion euros in total, but officials have already indicated the price tag could increase by up to EUR 100 million due to rising prices.