Upon opening in October 1906, the Karawanks Tunnel formed an important element of the Karawanken Railway, which was - together with the Bohinj Railway - constructed to connect the port of Trieste with Klagenfurt, the capital of the federal state of Carinthia in Austria. Despite the dissolution of the Austro-Hungarian Empire, which had been a driving force for its construction, the line and tunnel alike continued to be a well-trafficked route largely used by freight trains travelling between Austrian and Slovenia. During the twenty-first century, the Karawanks Tunnel underwent extensive modernisation, being rationalised from a twin-track layout to a single track to comply with modern safety standards.