The new Slovenian railway between Divača and Koper is not only progressing but will also be doubled. This is the country’s most significant infrastructure project, launched in September 2021 with the aim of creating a new route with gentler gradients and wider curves than the historic line. Initially, however, the decision was made to build only a single track due to budget constraints.
Construction and future management of the line are entrusted to the state-owned company 2DTK (Družba za razvoj projekta), which plans to complete the project and open the line by the end of March 2026. In October 2024, the Slovenian parliament approved plans for a second parallel track, creating a fully double-track railway. The decision was facilitated by the fact that major engineering works, such as tunnels, had been designed from the outset to allow for a second pair of rails, with the option of adapting service tunnels as needed.
2DTK has launched a tender for the design and environmental integration of the new infrastructure, marking the first step towards the doubling project. The tender, worth just under €30 million, was awarded to a consortium of companies including Elea iC, Irgo Consulting and SŽ Projektivno podjetje, the design arm of Slovenian Railways. Construction of the second track is expected to begin in 2026 and finish by 2030.
After a challenging start, work on the 27-kilometre Divača-Koper line—of which more than 17 kilometres are in tunnel—accelerated significantly in 2025, when over 80% of the works were completed. Tunnels and viaducts were built, paving the way for track laying. In July 2025, one of the key sections, from Koper to Črni Kal, was completed, including five tunnels totalling almost 12 kilometres and two viaducts. At the same time, work began on the completion of the Lokev tunnel towards Divača, the longest on the new route at 6.7 kilometres.
In its first phase, the new line will operate jointly with the historic route, with uphill traffic benefiting from the more favourable new alignment. Once the new line becomes fully double track, Slovenian Railways estimates that annual freight volumes serving the port of Koper will exceed 36 million tonnes. The Slovenian port already stands out for its high rail modal share, above 50%, with more than 20,000 trains a year according to 2023 data.
Piermario Curti Sacchi
