During the 1930s, railway construction in Turkey reached its peak, where of lines were completed. Ever since the Turkish State Railways were formed in 1927, railways extended to eastern Turkey. A main line was to be constructed from Ankara to Erzurum, where it would connect with the broad gauge line to the Turkey/Soviet Union border built by the Russian Empire in 1916.Transcaucasus Railways - Trains and Railways of Turkey Construction of the line started in 1924 (by the CFAB, TCDD took over in 1927) and reached Kayseri in 1927, Sivas in 1930 and Çetinkaya in 1936. The Eastern Express made its first run with the opening of the line to Çetinkaya. The railway finally reached Erzurum in 1939. In the same year the Eastern Express started operating from Haydarpaşa to Erzurum. By transferring to a broad gauge train in Erzurum, passengers could travel to Kars, the last Turkish city before the Soviet Union. In 1962, the broad gauge line from Erzurum-Kars-Akkaya was made standard gauge by the State Railways. The Eastern Express was extended to Kars in 1962.
