Question: The Southern Railway runs from Vienna to Graz and the border with Slovenia at Spielfeld via the first mountain railway built in Europe to use what kind of track?

full_context: Document 1: Southern (Govia Thameslink Railway): Southern is the brand name used by the Govia Thameslink Railway (GTR) train operating company on the Southern routes of the Thameslink, Southern and Great Northern franchise in England. It is a subsidiary of Govia, a joint venture between transport groups Go-Ahead and Keolis, and has operated the South Central rail franchise since August 2001 and the Gatwick Express service since June 2008. In July 2015, the franchisee was subsumed into GTR, but the Southern and Gatwick Express brand identities were retained alongside those of Thameslink and Great Northern.
Document 2: Eibsee Cable Car: The Eibsee Cable Car, which opened in 1963, is a cable car which connects the lower station (973 m above sea level) near lake Eibsee with the top station at 2950 m above sea level next to the summit of Zugspitze, Germany's highest mountain on the border to Austria. The cable car was built to provide a faster access to the Zugspitze from its German side, as the cog railway from Garmisch-Partenkirchen does not go directly to the summit and takes much longer. The "Eibsee Cable Car" belongs to "Bayerische Zugspitzbahn Bergbahn AG", the company operating the cog railway and most cable cars, gondola lifts and chairlifts in the Garmisch-Partenkirchen area. It is thus possible to make round trips using both the cog railway and the cable car. On the Austrian side, there is the Tyrolean Zugspitze Cable Car which starts at Ehrwald and meets the Eibsee Cable Car on the top.
Document 3: Southern Railway routes west of Salisbury: This article describes the history and operation of the railway routes west of Salisbury built by the London and South Western Railway (LSWR) and allied companies, which ultimately became part of the Southern Railway in the United Kingdom. Salisbury forms a natural boundary between the Southern Railway core routes in the counties surrounding London, and the long route connecting with the Devon and Cornwall lines.
Document 4: Main Southern railway line, New South Wales: The Main Southern Railway is a major railway in New South Wales, Australia. It runs from Sydney to Albury, near the Victorian border. The line passes through the Southern Highlands, Southern Tablelands, South West Slopes and Riverina regions.
Document 5: Slovenia: Slovenia ( ; Slovene: "Slovenija" ] ), officially the Republic of Slovenia (Slovene:    , abbr.: "RS"), is a nation state located in the southern Central Europe, variously classified as part of Eastern and Southern Europe. The country is located at the crossroads of main European cultural and trade routes. It is bordered by Italy to the west, Austria to the north, Hungary to the northeast, Croatia to the south and southeast, and the Adriatic Sea to the southwest. It covers 20,273 km2 and has a population of 2.06 million. It is a parliamentary republic and a member of the United Nations, European Union, and NATO. The capital and largest city is Ljubljana.
Document 6: Melbourne–Adelaide railway: The Melbourne–Adelaide railway is a standard gauge railway corridor that runs between the cities of Melbourne, Victoria and Adelaide, South Australia. Most of the current traffic is freight, though the only named and perhaps best known regular train is the twice-weekly passenger service "The Overland", operated by Great Southern Railways
Document 7: Styria: Styria (German: Steiermark , ] , Slovene/Croatian: "Štajerska" , Hungarian: "Stájerország" , ) is a state or "Bundesland", located in the southeast of Austria. In area it is the second largest of the nine Austrian federated states, covering 16401 km2 . It borders Slovenia and the Austrian states of Upper Austria, Lower Austria, Salzburg, Burgenland, and Carinthia. The population (as of ) was . The capital city is Graz which had 276,526 inhabitants at the beginning of 2015.
Document 8: Southern Railway (Austria): The Southern Railway (German: "Südbahn" ) is a railway in Austria that runs from Vienna to Graz and the border with Slovenia at Spielfeld via Semmering and Bruck an der Mur. It was originally built by the Austrian Southern Railway company and ran to Ljubljana and Trieste, the main seaport of the Austro-Hungarian Monarchy. The twin-track, electrified section that runs through the current territory of Austria is owned and operated by Austrian Federal Railways (ÖBB) and is one of the major lines in the country.
Document 9: Bernina railway: The Bernina railway is a single-track railway line forming part of the Rhaetian Railway (RhB). It links the spa resort of St. Moritz, in the Canton of Graubünden, Switzerland, with the town of Tirano, in the Province of Sondrio, Italy, via the Bernina Pass. Reaching a height of 2,253 m above sea level, it is the highest railway crossing in Europe and the third highest railway in Switzerland. It also ranks as the highest adhesion railway of the continent, and – with inclines of up to 7% – as one of the steepest adhesion railways in the world. The Bernina railway is also notable for its big height difference on the section between the Bernina Pass and Tirano: (1824 m ), allowing passengers to see glaciers and palm trees on the same line.
Document 10: Semmering railway: The Semmering railway (German: "Semmeringbahn" ) in Austria, which starts at Gloggnitz and leads over the Semmering to Mürzzuschlag was the first mountain railway in Europe built with a standard gauge track. It is commonly referred to as the world's first true mountain railway, given the very difficult terrain and the considerable altitude difference that was mastered during its construction. It is still fully functional as a part of the Southern Railway which is operated by the Austrian Federal Railways.
Document 11: Standard gauge: The standard gauge (also Stephenson gauge named after George Stephenson, International gauge, or normal gauge) is a widely used railway track gauge. Approximately 55% of the lines in the world use this gauge. All high-speed rail lines, except those in Russia, Uzbekistan, Finland and Australia, utilize standard gauge. The distance between the inside edges of the rails is defined to be 1435 mm except in the United States, where it is still defined in Imperial and US customary units as approximately 4 ft 8½ in. It is also called the UIC gauge or UIC track gauge, the European gauge in the EU and Russia, or uniform gauge in Queensland, Australia.u
Document 12: Tauern Railway: The Tauern Railway (German: "Tauernbahn" ) is an Austrian railway line between Schwarzach-Sankt Veit in the state of Salzburg and Spittal an der Drau in Carinthia. It is part of one of the most important north-south trunk routes ("Magistrale") in Europe and also carries tourist traffic for the Gastein Valley. The standard gauge railway line is 79 km long and climbs the High Tauern range of the Central Eastern Alps with a maximum incline of 2.5%, crossing the Alpine crest through the 8371 m long Tauern Tunnel. It is one of the highest standard gauge railways in Europe and the third highest in Austria.
Document 13: Reisseck Railway: The Reisseck Railway (sometimes Reißeck Railway, German: "Reißeckbahn" ) is a mountain railway, that runs from Carinthia's Möll valley into the Reißeck Group, a small mountain range in southern Austria. It comprises the Reisseck Funicular and the Reisseck Mountain Railway (a narrow gauge railway).
Document 14: Tauern Railway Tunnel: The Tauern Railway Tunnel (German: "Tauerntunnel" ) in Austria is the longest tunnel of the Tauern Railway crossing the main chain of the Alps. Currently, it has a length of 8.371 km . The highest point of the tunnel, which is also the highest point in all of the railway line, is at 1226 m above sea level. The tunnel's north entrance is at Böckstein in the valley of Bad Gastein in the state of Salzburg, the south entrance near Mallnitz in Carinthia.
Document 15: Most–Moldava railway: The Most–Moldava railway is a branch line in Czech Republic, which was originally built and operated by the Prague-Dux Railway. The line, formerly known as the"Teplitz Semmering Railway" ("Teplitzer Semmeringbahn") runs from Most ("Brüx") over the Ore Mountains to Moldava ("Moldau") and used to have a junction with the Nossen-Moldau railway there in Saxony until 1945. In the Czech Republic the line is known today as the "Moldavská horská dráha" ("Moldau Mountain Railway") or "Krušnohorská železnice" ("Ore Mountain Railway").
ground_truth: standard gauge track