The Trans-Mongolian Railway connects the Trans-Siberian Railway from Ulan Ude in Russia to Erenhot and Beijing in China through the capital Ulaanbaatar. The Mongolian section of this line runs for 1110 km. A spur line connects Darkhan to the copper mines of Erdenet; another spur line connects Ulaanbaatar with the coal mines of Baganuur.
A separate railway line is in the east of the country between Choibalsan and the Trans-Siberian at Borzya; however, that line is closed to passengers beyond the Mongolian town of Chuluunkhoroot. For domestic transport, daily trains run from Ulaanbaatar to Darkhan, Sukhbaatar, and Erdenet, as well as Zamyn-Üüd, Choir and Sainshand. Mongolia uses the 1,520 mm (4 ft 11 27⁄32 in) (Russian gauge) track system. The total length of the system 1,810 km. In 2007, rail transport carried 93% of Mongolian freight and 43% of passenger turnover (in tons*km and passenger*km, respectively).
In 2007, only about 2600 km of Mongolia’s road network were paved. Another 3900 km are graveled or otherwise improved. This network of paved roads was expanded to 4,800 km in 2013, with 1,800 km completed in 2014 alone. This included the roads from Ulaanbaatar to the Russian and Chinese borders, paved road from Ulaanbaatar to Kharkhorin and Bayankhongor, another going south to Mandalgovi, and a partly parallel road from Lün to Dashinchilen, as well as the road from Darkhan to Bulgan via Erdenet. The vast majority of Mongolia’s official road network, some 40,000 km, are simple cross-country tracks.
Construction is underway on an east-west road (the so-called Millennium Road) that incorporates the road from Ulaanbaatar to Arvaikheer and on the extension of the Darkhan-Bulgan road beyond Bulgan. Private bus and minibus companies offer service from Ulaanbaatar to most aimag centers.
Mongolia has 580 km of waterways, but only Lake Khövsgöl has ever been heavily used. The Selenge (270 km) and Orkhon (175 km) rivers are navigable but carry little traffic, although a customs boat patrols the Selenge to the Russian border. Lake Khovsgol has charter boats for tourists. The lakes and rivers freeze over in the winter and are usually open between May and September.
As of 2012, most airports of 21 aimag centers of Mongolia have paved runways. Those closest to Ulaanbaatar lack scheduled air service.
Chinggis Khaan International Airport outside of Ulaanbaatar is the major airport in Mongolia that offers international flights. There are other airports that have international status such as the ones in Choibalsan and Khovd towns that connect nearby Chinese cities of Ürümqi, Hailar, Erenhot and Manzhouli: They are more popular among the local population.
As of 2013, domestic air carriers such as MIAT Mongolian Airlines, Eznis Airways (unexpectedly suspended its operation on May 22, 2014) Aero Mongolia, Hunnu Air as well as international carriers such as Aeroflot, Korean Air, Air China and Turkish Airlines are offering scheduled services. Domestic airlines except MIAT Mongolian Airlines provide regular service between Ulaanbaatar and aimag centers. Domestic flights are operated using Fokker 50, Saab 340 (EZNis discontinued to use these aircraft as of late 2013-early 2014), Airbus 319 and Bombardier Q400 aircraft.
Ulaanbaatar can be accessed with regular flights from major cities such as Moscow, Berlin, Frankfurt, Beijing, Hong Kong, Singapore, Shanghai (discontinued in October 2013), Seoul, Tokyo, Osaka (served only in summer), Bangkok (discontinued by Hunnu Air), Istanbul and Bishkek. In June 2014, Hunnu Air launched its previously announced flight to Paris but discontinued it shortly after.
In 2013 the first purely air cargo operator was registered at the Civil Aviation Authority of Mongolia and is planned to commence operation in 2014.