ÖBB Completes 27.3-kilometer Semmering Base Tunnel Excavation

GLOGGNITZ, AUSTRIA – Austrian Federal Railways (ÖBB) completed a milestone transit of the Gloggnitz Tunnel by minibus in mid-2025, signaling the end of excavation works for the Semmering Base Tunnel project. The 27.3-kilometer tunnel, which began construction nearly 15 years ago, has now entered its final three-year technical outfitting phase. Regular passenger and freight rail operations on the high-speed line are scheduled to commence at the end of 2029.

What Is the Full Scope of This Project?

The Semmering Base Tunnel project consists of a 27.3-kilometer twin-tube railway link designed to bypass the historic, capacity-constrained Semmering mountain route. The total length of all excavated tunnel tubes, shafts, and cross-passages reaches 62 kilometers. Following the final structural breakthroughs achieved at the end of 2024, works shifted in the summer of 2025 to the installation of track infrastructure, traction power cabling, telecommunications, and signaling systems. ÖBB expects the technical outfitting phase to span over 36 months due to the logistical complexity of the twin-bore design. The completed corridor will reduce passenger transit times between Vienna and Graz to 1 hour and 50 minutes, representing a savings of approximately 30 minutes. Specific details regarding the minibus routing used by the delegation inside the unfinished structure were not publicly disclosed by the operator.

Key Project Data

How Does This Compare to Similar Projects?

The Semmering Base Tunnel represents one of Central Europe’s largest active rail infrastructure undertakings, comparable in regional scale to the Koralm Railway project. The 33-kilometer Koralm Tunnel, also managed by ÖBB, is slated to open for service in December 2025 after a similar multi-decade development timeline (Source: ÖBB, 2023). While the Koralm Tunnel is longer at 33 kilometers compared to the Semmering’s 27.3-kilometer main section, both projects serve as critical links in Austria’s Southern Route (Südstrecke) modernization, aiming to shift heavy freight from road to rail along the Baltic-Adriatic Corridor. Independent verification of specific railway contract values for the 2024–2025 period was not available in the provided market data at the time of publication.

Editor’s Analysis

The commissioning of the Semmering Base Tunnel in 2029 will fundamentally restructure freight logistics across the Baltic-Adriatic corridor by eliminating the steep gradients of the existing mountain pass. By allowing longer, heavier freight trains to operate without auxiliary locomotives, ÖBB will significantly lower operational costs and increase capacity to meet Austria’s goal of shifting 30% of freight to rail by 2040 (Source: Austrian Federal Ministry of Mobility, 2024). This shift is critical as cross-border trade between Central European economies continues to demand more sustainable supply chain solutions.

FAQ

Q: What is the total length of the Semmering Base Tunnel?
A: The main tunnel section of the Semmering Base Tunnel is 27.3 kilometers long. When accounting for all auxiliary shafts, emergency stations, and connecting tubes, the total length of the underground network reaches 62 kilometers.

Q: When will the Semmering Base Tunnel officially open for train traffic?
A: The first commercial trains are scheduled to run through the tunnel at the end of 2029. This follows a three-year technical outfitting phase that began in the summer of 2025.

Q: How will the Semmering Base Tunnel affect passenger travel times between Vienna and Graz?
A: Travel times between Vienna and Graz will be reduced to approximately 1 hour and 50 minutes. This cuts the current journey time by about 30 minutes, bypassing the slow mountain route.