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?
Related documents: [0]  [DOC] 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. [END] 
[1]  [DOC] 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. [END] 
Answer: 
standard gauge track
standard gauge track