The Slovenia Times

Karavanke tunnel breakthrough delayed until spring

A second tube of the Karavanke motorway tunnel under construction. Photo: Tinkara Zupan/STA

A second tube of the Karavanke motorway tunnel is slated for opening in autumn 2025. While Austria excavated its section a while ago, work on the Slovenian side has been delayed by the tricky terrain, putting off a breakthrough until next spring.

The Slovenian motorway company DARS told the Slovenian Press Agency that 2,710 metres of the tube had been excavated by mid-October, while another 735 metres remained to be bored.

A breakthrough was initially slated for this autumn but the plans have been thwarted by the difficult geological conditions on the Slovenian side of the mountain range.

If these conditions do not deteriorate and there are no major intrusions of mountain water, workers will reach the Austrian border in the first four months of 2024, DARS said.

The geological structure of the Karavanke is quite diverse, which makes it hard to anticipate the pace of tunnelling in detail in advance as the full picture of the geological and geotechnical conditions does not become clear until work is done on the ground, DARS explained.

On a positive side, the structure of the terrain gets more homogenous as the work nears the Austrian side, DARS said, adding that the situation was similar when the first tube was being excavated 30 years ago.

The Slovenian side of the second tube is 3.5 km long, while the Austrian section is a kilometre longer, yet the Austrians reached the Slovenian border back in September 2021.

Work on the Slovenian side had been initially delayed by issues surrounding the selection of the contractor and then by Covid-19 restrictions.

DARS first published a public call to pick a contractor for the project in December 2017, but the process has been delayed by continuous appeals.

Eventually, Cengiz, a Turkish contractor, was picked in 2019. It started boring the tunnel in August 2020, nearly two years after Austria began working on its side.


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