There is also a case to be made for a rail line from the Caucasus to the city of Kars:
This railway was actually used in WW1 to supply the Russian troops, so that has to count for something.
It went West as far as Erzurum. Built by the Russians and using their gauge. The railway was built in the 1,520 mm (4 ft 11 27⁄32 in) "Russian Gauge", from Tbilisi to Kars, which the Ottomans lost in 1878 to the Russian Empire. The Trancaucasus Railway extended the line to Sarıkamış in 1913 and during World War I built a 750 mm (2 ft 5 1⁄2 in) narrow gauge line from Sarıkamış to Erzurum. After the war, the newly formed Republic of Turkey took back Kars and took over the two rail lines. The Turkish State Railways continued the former CFOA's work and built a railway from Ankara to Kayseri in 1927. The railway was completed to Sivas in 1930, Çetinkaya in 1936, Erzincan in 1938 and Erzurum in 1939. However the line from Erzurum to Kars was broad gauge until the State Railways converted into standard gauge in 1962.
Also found this regarding the track from Ankara to Erzurum:
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. 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.
So, it seems that in 1939 it was possible to travel between Ankara (Turkey) and Tblisi (USSR) by rail. There were still different gauges on the route, but the railway was there.
< Message edited by PanzerMike -- 2/27/2020 7:34:51 PM >