In the late 1990s, seven variants were produced to accommodate the route of the second track of the Divača-Koper railway line. Among them were also variants that run completely or partially parallel to the existing track.
Already in 2005, it was the most appropriate confirmed current tunnel route, it was also supported by all local communities and competent ministries. The government at the time also accepted itRegulation on the National Location Plan. In 2014, amendments to the regulation were adopted, on the basis of which the route was finally placed in the space.
A total of 17 different route variants were examined, namely ten in the route selection process and an additional seven for evaluation by European financial institutions and technical control by the Jaspers agency. From technical, environmental, economic and safety aspects, it turned out that the selected route is optimal.