Trans-Siberian Railway one side of the lake to the other until the completion of the Lake Baikal spur along the southern edge of the lake. With the Amur River Line north of the Chinese border being completed in 1916, there was a continuous railway from Petrograd to Vladivostok that remains to this day the world's longest railway line. Electrification of the line, begun in 1929 and completed in 2002, allowed a doubling of train weights to 6,000 tonnes. There were expectations upon electrification that it would increase rail traffic on the line by 40 percent. The additional Chinese Eastern Railway was constructed
Trans-Mongolian Railway line began in 1947, reaching Ulan Bator from the north in 1950 and the Chinese border in 1955. Before that the only railways in Mongolia had been a line (opened in 1938) connecting the coal mines at Nalaikh to the capital and a Soviet-built freight-only branch (completed in 1939) from Borzya on the Trans-Siberian Railway to Bayantümen, Dornod near Choibalsan in north-eastern Mongolia. Russian Irkutsk State University of Railway Engineering opened its Ulaanbaatar branch in June 2009. The Mongolian Railway company "Mongolyn Tömör Zam" carries 80% of all freight and 30% of all passenger transport within Mongolia. In the aftermath