Multi-million euro project with three construction phases on the S 6 Semmering Expressway; Completion by the end of 2029

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, both structurally and technically, the tunnels now need to be brought up to date. Starting on April 28, the total of 21 kilometers of tunnels (10.5 kilometers in each direction) will be completely renovated. The work will be divided into three phases, starting with the two tunnels, Ganzstein and Spital, which will be renovated and equipped with the latest safety equipment by May 2027. This will be followed by the Steinhaus and Semmering tunnels (by July 2029), and the final phase, until the end of 2029, will see the modernization of the two short tunnels, Eselstein and Grasberg.

The project not only significantly improves tunnel safety, but also represents a massive investment for Austria as a business location. ASFINAG is investing a total of approximately €270 million in the general renovation of the infrastructure and in new, modern safety equipment for the tunnels.

Closure of one lane required in each direction

The tunnel work requires the closure of one lane at a time, so traffic will be diverted into the open tunnel tube, leaving one lane available in each direction. Speed ​​limits must therefore be reduced to 80 km/h for safety reasons.

The tunnel tubes of the Ganzstein and Spital tunnels in the direction of St. Michael will be renovated by May 2026, followed by the tubes toward Seebenstein.

Top-notch security systems and additional escape routes

The following will be renewed in all tunnels, among other things:

Power distribution
Lighting (LED systems)
Fire alarm systems
Sensors such as cloudy sky, CO, measurement and detection systems
Video system
Emergency call system
Radio system
Ventilation (except for Grasberg and Eselstein)
Firefighting and wastewater systems
Water protection systems
A total of 15 additional escape routes (connecting tunnels to the other tunnel tubes) will also be built.

ASFINAG is also building several photovoltaic systems along the Semmering tunnel chain to generate electricity for the tunnels themselves, in line with ASFINAG's sustainability strategy.

The timeline in detail

By May 2026: Ganzstein and Spital tunnels (2.1 and 2.5 kilometers respectively) General renovation of the St. Michael-bound carriageway

By March 2027: Ganzstein and Spital tunnels, Seebenstein-bound carriageway

From April 2027 to June 2028: Steinhaus and Semmering tunnels (1.8 and 3.5 kilometers) General renovation of the St. Michael-bound carriageway

June 2028 to July 2029: Steinhaus and Semmering tunnels, Seebenstein-bound carriageway

July 2029 to the end of 2029: Grasberg and Eselstein tunnels (370 meters and 180 meters)

source: ASFINAG. press release (original in German)