Overhaul of the Semmering Tunnel Chain for 270 Million Euros
For more than 20 years, the six tunnels of the Semmering tunnel chain on the S 6 have been the fastest and, above all, safest connection between Styria and Lower Austria. However, it is now necessary to modernize the tunnels both structurally and in terms of technical equipment. Since April 28, 2025, the 21 kilometers of tunnels (10.5 km in each direction) are being completely renovated.
Planned Completion at the End of 2029
The work will be divided into three stages, starting with the Ganzstein and Spital Tunnels. These will be renovated and equipped with state-of-the-art safety equipment by May 2027. Next come the Steinhaus and Semmering Tunnels (until July 2029), and in the final phase until the end of 2029, the two short tunnels Eselstein and Grasberg will be modernized. In total, Asfinag is investing around 270 million euros in the general refurbishment of the infrastructure and in the new, modern safety equipment for the tunnels.
The renovation of the Semmering tunnel chain has already begun at the Ganzstein Tunnel
Credit/Quelle: ASFINAG
Safety Systems and Additional Escape Routes
Work on the tunnels requires the closure of one tube at a time. Work will begin with the Ganzstein and Spital tunnels in the direction of St. Michael, which will be renovated by May 2026; after that, the tubes in the direction of Seebenstein will follow.
Renewals in all tunnels will include:
Energy distribution
Lighting (LED systems)
Fire alarm systems
Sensors such as obscured vision, carbon monoxide, measurement and detection systems
Video system
Emergency call system
Radio system
Ventilation (except Grasberg and Eselstein)
Extinguishing and waste water systems
Water protection systems
A total of 15 additional escape routes (connecting tunnels to the other tube)
Several photovoltaic systems will also be installed along the Semmering tunnel chain to generate electricity for the tunnels.
Detailed Timeline
Until May 2026: Ganzstein Tunnel (2.1 km) and Spital Tunnel (2.5 km), general refurbishment in the direction of St. Michael
Until March 2027: Ganzstein Tunnel and Spital Tunnel, general refurbishment in the direction of Seebenstein
April 2027 to June 2028: Steinhaus (1.8 km) and Semmering Tunnels (3.5 km), general refurbishment in the direction of St. Michael
June 2028 to July 2029: Steinhaus and Semmering Tunnels, general refurbishment in the direction of Seebenstein
July 2029 to the end of 2029: Grasberg (370 m) and Eselstein (180 m) Tunnels
