2TDK published two calls for applications for the EUR 1bn-plus project on 11 November 2019 - one for the construction of the track between Divača and Črni Kal, and the other between Črni Kal and Koper.

The project was split in two, because of geological structure of the terrain and the lower price expected as a result.

"The first section involves construction on karst terrain, the second on flysch. This alone calls for splitting the project in two," 2TDK head Marko Brezigar said last November.

He also pointed to international studies that show dividing a project into two parts increases competition.

2TDK moreover decided for a two-stage tender process, in which the competences of the bidders are examined first and only then prices discussed. Ten out of 15 companies that applied to the first call were assessed as suitable, and 10 out of the 14 that applied to the second call.

Most of the companies that applied are Chinese, some are Turkish, including Cengiz, which is constructing the second tube of the Karavanke motorway tunnel. Among Slovenian companies that were assessed as appropriate are Kolektor CPG and Gorenjska Gradbena Družba.

The former has formed a consortium with the Turkish Yapi Merkezi and Özaltin, and the latter with Czech construction giant Metroslav.