Construction begins on the Pfaffensteig Tunnel: work on the Gäubahn extension is progressing

With a symbolic groundbreaking ceremony, Deutsche Bahn, together with a number of partners, began construction of the Pfaffensteig Tunnel. From 2033, it will link the Gäubahn – running to and from Zurich – with the Stuttgart 21 infrastructure. What makes the construction of the approximately eleven-kilometre-long tunnel and the subsequent approximately three-kilometre stretch of track between the tunnel and Böblingen so special is that the new infrastructure is being built under the so-called ‘rail partnership model’. Under this model, Deutsche Bahn and its alliance partners are planning and building everything together from day one and are also jointly responsible for the timetable and costs.

Evelyn Palla, CEO of DB AG: “The Pfaffensteig Tunnel doesn’t just save journey time. It creates time for people. Anyone who commutes every day knows how valuable every minute is. With this project, we are bringing the region closer together and improving connections to the airport and long-distance services. At the same time, by starting construction today, we are demonstrating that major infrastructure projects can become a reality more quickly when all those involved take joint responsibility.”

Steffen Bilger, Federal Minister for Transport: “From the initial concept right through to today’s start of construction, I have had the privilege of supporting and driving forward the Pfaffensteig Tunnel project over many years. That is why this day is also very special to me personally. Our goal was clear from the outset: we want an efficient Gäubahn, faster connections between Stuttgart and Zurich, and better links for travellers throughout the region. With the Pfaffensteig Tunnel, we are creating a key prerequisite for this and making the Gäubahn ready for the Germany-wide integrated timetable. The fact that what was once just an idea is now becoming a concrete piece of infrastructure shows that it pays to be persistent with important rail projects and to work together to pick up the pace.”

Nicole Razavi, Minister for Transport of Baden-Württemberg: “The Pfaffensteig Tunnel is a key component of a modern, efficient and safe rail infrastructure in Baden-Württemberg. Fast rail links from Switzerland, Lake Constance and the Gäu region to the airport and the state capital are beneficial for commuters, business travellers, holidaymakers and the economy of Baden-Württemberg. Whilst we are delighted about the construction, it is important that the impact on operations during the construction phase is minimised and closely coordinated with the funding authorities and local authorities. I believe DB has a responsibility here.”

Dr Frank Nopper, Mayor of the state capital Stuttgart: “The Pfaffensteig Tunnel paves the way for better rail links for the city, the region and the state: it makes rail travel to and from the south more attractive, as it reduces journey times and connects the airport and the exhibition centre directly to the Gäubahn.”

Rainer Wieland, Chair of the Stuttgart Region Association: “Thanks to the Pfaffensteig Tunnel, there will continue to be no mixed-use traffic on the S-Bahn line between Rohr and the airport. This will have a positive impact on the operational quality of the S-Bahn. Furthermore, commuters from Böblingen and Herrenberg will reach Stuttgart Central Station much more quickly. The Pfaffensteig Tunnel will fully connect not only the south of the region but also the south of Baden-Württemberg to the new Stuttgart Airport transport hub. At the same time, it opens up new opportunities for the expansion of the S-Bahn: the Panoramabahn can thus be used in future for the planned S7 line from Heimerdingen to Stuttgart-Vaihingen.”

Stefan Kratochwill, Chairman of the Executive Board of STRABAG SE: “The Pfaffensteig Tunnel is a project that places the highest demands on planning, coordination and construction. Today’s tunnel break-ground ceremony marks the transition from intensive joint preparation to visible implementation. Together with Deutsche Bahn and our partners, we are relying on state-of-the-art tunnelling technology, digital planning methods and a collaborative approach to project management. In this way, we are laying the foundations for realising this complex construction project efficiently, with a focus on the future and to a high standard of execution.”

Commissioning in 2033
The aim of the ‘Rail Partnership’ model is to complete complex large-scale projects more quickly and cost-effectively. In contrast to the previous, conventional approach to major projects, DB, together with its alliance partners FCP, Geoconsult, Hörmann, iC-Consulenten, Rhomberg Bahntechnik, Spitzke, Strabag, Swietelsky, Wayss & Freytag and Züblin, has drawn up a cross-trade schedule in addition to the design and planning for regulatory approval. Time and budget risks were jointly identified, assessed and factored into the schedule and cost framework. Passengers are expected to be able to use the new tunnel from 2033 onwards.

Pfaffensteig Tunnel connects the Gäubahn with Stuttgart 21
The expansion of the Gäubahn – and thus also the construction of the Pfaffensteig Tunnel – is listed as a priority in the Federal Rail Network Development Plan. Consequently, as part of the Federal Rail Network Expansion Act, the Pfaffensteig Tunnel is in the ‘overriding public interest’. The construction of the project was agreed between the Federal Government and DB InfraGO AG at the end of 2025.
The Pfaffensteig Tunnel will connect the Gäubahn to the airport and, further on, to the future Stuttgart Central Station. The tunnel thus also fulfils a significant part of the financing agreement concluded by the Stuttgart 21 project partners.
The tunnel will enable journey times between Stuttgart and Zurich to be reduced by around 15 minutes. This will also improve connections along the route. Many passengers will also benefit from the journey time between Böblingen and the airport being reduced from the current 22 minutes to around 7 minutes in future. In addition, passengers travelling on the Gäubahn will in future be able to change conveniently at the airport onto fast services towards Ulm and Munich – and vice versa.

The planning for the Gäubahn North Extension project, including the Pfaffensteig Tunnel, is divided into sections. The planning permission granted for Planning Approval Section (PFA) 1 at the end of 2025 covers the 10.8-kilometre section of the Pfaffensteig Tunnel to be excavated. PFA 2 comprises the approximately 300-metre-long section of the Pfaffensteig Tunnel to be constructed using open-cut methods, followed by the approximately 3-kilometre-long above-ground section of track leading to the Goldberg S-Bahn station, situated between Böblingen and Sindelfingen. Deutsche Bahn submitted the planning approval documents for the second project section to the Federal Railway Authority (EBA) in April 2025. Today’s symbolic ground-breaking ceremony took place at the future emergency tunnel of the Pfaffensteig Tunnel in the presence of the tunnel’s patron, Andrea Klett-Eininger.

Here you will find the original press release from Deutsche Bahn