Railroad section Logatec - Črni Vrh. The remains from first world war of the planed railway tunnel of the normal size rails is located below the Naklo area in town Logatec. The length of the tunnel is 198 m with the azimuth of 35° .
Town Logatec represented important logistic centre during the first world war for the Austro-Hungarian Army fighting on the Italian front along Soča River. 20.000, mostly Russian prisoners of war built a narrow gauge railway to Idrija. It was planned also a normal size rail railway to Godovič direction. The tunnel below Naklo was built but never used due the Austro-Hungarian (+German) break of the Italian front in 12th battle in October 24th 1917, so there was no need for that railway »bypass« connection.