Complex sentence: The Semmering Railway, Austria, which starts at Gloggnitz and leads over the Semmering to Muerzzuschlag--is still full functioning-was the first mountain railway of Europe built with a standard gauge track.
Split into simpler sentences: The Semmering Railway, Austria, which starts at Gloggnitz and leads over the Semmering to Muerzzuschlag is still fully functioning. It was the first mountain railway in Europe built with a standard gauge track.