The building of Šargan Railway, as they usually call the part between Užice and Vardište, begun on the 1st of March 1921, by the Sarajevo Direction. Because the process was very slow, the Minister of Transport in The Kingdom of SCS decided to change the way of building. On October 1921 the railway was rented at the auction to the enterprise "Fenix", precisely, the part between Užice and Šargan tunnel. From Šargan to Mokra Gora, including the tunnel bellow Šargan, the construction was committed to the enterprise of Nikola Plavšić. The finalizing date was 24th of April 1924.
After they have taken away the business from the firm of Nikola Plavšić, The Committee for the Finalizing of Šargan "Eight" Project finished the works on the committed part (22.8 km) and the first train passed the railway on January 25th, 1925. The parts on this track were Šargan - Vitaši - Jatare (7.5 km), Jatare - Mokra Gora (7.8 km) and Mokra Gora - Vardište (7.5 km). At the same time, several gaps, bridges, supportive walls and tunnels were built and one of them, Šargan tunnel was 1,666 meters long.