The article considers the process of railway construction № 12 from Irkutsk to Slyudyanka during the Great Patriotic War. The author emphasizes the builders’ living conditions during the war. The constriction works were carried out in two stages. The first stage works were characterized by mobilization activities, later the construction was stopped. At the second stage (from 1944) war engineers and construction machinery were sent there. The author focuses on the brave feat of the builders, carried out construction works during the war.