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The Semmering Railway (German: Semmeringbahn) is an Austrian railway going from Gloggnitz to Mürzzuschlag, over the Semmering Pass. The Semmeringbahn was the first mountain railway in Europe built with a standard gauge track. It travels through very difficult mountainous terrain and handles major altitude differences along its 41 km long route.

The Semmeringbahn was made possible thanks to no less than 14 tunnels, including the 1,431 meter long vertex tunnel. There are also 16 viaducts, of which several are two-story, and more than one hundred curved stone bridges and 11 small iron bridges.

When the Semmeringbahn was opened in the 1850s, it contributed greatly to turning the Semmering region into a popular tourist destination, and many hotels were erected with a convenient distance from the railway.

Short facts about the Semmeringbahn

Track gague 1435 mm
Line length 41 km
Minimum radius 190 m
Maximum incline 2.50%

15 kV, 16⅔ Hz Overhead line


  • The Semmeringbahn is a part of the Southern Railway and operated by the Austrian Federal Railways.
  • The Semmeringbahn was added to the UNSECO World Heritage List in 1998.
  • The altitude difference is 460 meters.
  • On 60% of the line, the gradient is 2.0 – 2.5%.
  • 16% of the line exhibit a curvature radius of no more than 190 metres.


The Semmeringbahn was built in 1848 – 1854 under the direction of Carl von Ghega. Carl von Ghega, who also served as the project’s designer, was originally named Carlo Ghega. His family was from Albania but lived in Venice when Carlo was born. A total of approximately 20,000 workers were involved in the construction of the Semmeringbahn.

As mentioned above, the Semmeringbahn was the first mountain railway in Europe built with a standard gauge track, and several new tools and methods had to be developed to handle the challenges. Among other things, the railway had to overcome an altitude difference of 460 meters. The extreme gradients and turning radii also meant that the locomotives had to be adapted and fitted with new technical solutions.

Many of the stations and the buildings for railway supervisors were constructed from the waste material produced when the 14 tunnels were excavated.


To decide which locomotives to use for the new railway, a competition was arranged. To qualify, a locomotive had to be able to maintain a speed of 11.5 km/h and handle a maximum axle loading of 14 tonnes, with a boiler pressure not exceeding 8.5 kgf/cm². There were also curves with a minimum radius of 190 metres and a maximum radius of 285 metres to take into account, as well as one particular stretch of line with gradients of 1 in 40 (2.5%).

Four locomotives participated in the contest:

  • Bavaria from Maffei (Tyskland)
  • Neustadt from Wiener Neustädter Lokomotivfabrik (Österrike)
  • Seraing from Société anonyme John Cockerill (Belgium)
  • Vindobona from Wien-Gloggnitzer Bahn Lokomotivfabrik (Österrike)

All four met the basic criteria, but none of them were good eough to be selected for the Semmeringbahn. The contest did however lead to several improvements in locomotive construction, including Fairline’s 1863 patent, The Mallet Locomotive and The Mallet Locomotive.

Finally, a locomotive developed by Wilhelm Freiherr von Engerth appeared, with articulated tender as part of the main locomotive frame. This novel (and eventually patented) construction caused some of the weight of the tender to rest on the driving wheels, giving the locomotive improved adhesion. Simultaneously, the articulation made the locomotive supremely suitable for the narrow curves of the Semmeringbahn.

A total of sixteen Enghert locomotives were purchased by the Semmeringbahn between November 1853 and May 1854. They had no problem reaching the 11.5 km/h speed requirement, in fact, they could actually go 19 km/h on uphill gradients of 1 in 40 (2.5%).

The Semmering Base Tunnel

Work on the Semmering Base Tunnel commenced in 2012 but the link is not expected to enter service until 2026. When the tunnel is completed, it will go from Gloggnitz to Mürzzuschlag, underneath the Semmering Pass.