STRABAG and ZÜBLIN Secure Major German Rail Infrastructure Contract for Pfaffensteig Tunnel Project

The connecting pipe for the Pfaffensteig Tunnel has already been built in the airport’s
long-distance train station (right), and the switch connection and the first few meters of
track are also already in place.
© DB PSU

(IN BRIEF) STRABAG and ZÜBLIN have been awarded a major contract for the Pfaffensteig Tunnel project in Germany, a significant rail infrastructure scheme designed to improve connections between Stuttgart and Switzerland. The approximately 11-kilometre twin-bore tunnel will link Stuttgart Airport’s long-distance railway station with the existing Gäubahn line, helping reduce travel times and strengthen cross-border rail connectivity. The project will be delivered using an Integrated Project Delivery partnership model aimed at improving efficiency through early collaboration between project participants. Additional works include above-ground rail upgrades, tunnel sections, retaining structures, and infrastructure modernization to support train speeds of up to 200 km/h.

(PRESS RELEASE) STUTTGART/ VIENNA, 11-May-2026 — /EuropaWire/ — STRABAG, together with Group company ZÜBLIN, has secured a major infrastructure contract for the structural implementation of several procurement packages linked to the Pfaffensteig Tunnel project in Germany, a key component in the expansion of the Gäubahn railway corridor connecting Stuttgart with Switzerland.

The project, commissioned by DB Projekt Stuttgart–Ulm GmbH, is regarded as one of the most important rail infrastructure developments in south-west Germany and forms part of broader efforts to strengthen climate-friendly transportation and cross-border rail connectivity within Europe.

The Pfaffensteig Tunnel will create a direct rail connection between the new long-distance railway station at Stuttgart Airport and the existing Gäubahn line. Once completed, the project is expected to reduce travel times between Stuttgart and the Swiss border while supporting greater integration within the trans-European rail network.

The approximately 11-kilometre tunnel will be constructed as a twin-bore structure with a separate rail track in each tunnel tube. Around 9.8 kilometres of the main tunnel section will be excavated using two tunnel boring machines, while more complex crossings beneath the A8 motorway and the new railway line, including links to the underground long-distance station at Stuttgart Airport, will be completed using conventional tunnelling techniques.

The project is divided into two approval sections. The first section focuses primarily on the construction of the main tunnel infrastructure, while the second section includes additional engineering works such as a 240-metre cut-and-cover tunnel section, trough structures, railway underpasses, retaining walls, and grade-separated crossings.

Pfaffensteig Tunnel (map view)
© OpenStreetMap contributors (maps.strabag.com) and the GIS User Community /
STRABAG

The second phase will also include upgrades to approximately three kilometres of above-ground rail infrastructure, including partial realignment and modernization work to support train speeds of up to 200 km/h.

Jörg Rösler described the Pfaffensteig Tunnel as both a major infrastructure project and a significant contribution toward sustainable and future-oriented mobility in Germany. He also emphasized the importance of collaborative project delivery models in accelerating complex infrastructure developments.

The project will be executed using an Integrated Project Delivery (IPD) partnership model, a collaborative multi-party contractual framework designed to improve efficiency during the planning, design, and construction phases of large-scale infrastructure projects. Under the IPD approach, contractors and project partners become involved during the design and permitting stages, allowing expertise to be integrated earlier in the process to accelerate delivery timelines and reduce overall costs.

Several STRABAG Group entities are participating across multiple procurement packages within the project. Package 2, covering tunnelling works, will be executed by Ed. Züblin AG in a joint venture with Wayss & Freytag Ingenieurbau AG. STRABAG AG will oversee Package 3, which includes earthworks, while Package 4 covering structural engineering will again be delivered by a joint venture between Ed. Züblin AG and Wayss & Freytag Ingenieurbau AG.

The Pfaffensteig Tunnel project reflects wider investment trends across Europe aimed at expanding rail capacity, modernizing transport infrastructure, and supporting climate targets through increased use of rail-based mobility alternatives.

STRABAG, which operates across the full construction value chain, said the project also aligns with its broader focus on sustainable construction methods, innovation, and climate-neutral infrastructure development.

STRABAG SE is a European-based technology group for construction services, a leader in innovation and financial strength. Our activities span all areas of the construction industry and cover the entire construction value chain. We create added value for our clients by taking an end-to-end view of construction over the entire life cycle – from planning and design to construction, operation and facility management to redevelopment or demolition. In all of our work, we accept responsibility for people and the environment: We are shaping the future of construction and are making significant investments in our portfolio of more than 250 innovation and 400 sustainability projects. Through the hard work and dedication of our approximately 89,000 employees, we generate an annual output volume of around € 20 billion.
Our dense network of subsidiaries in various European countries and on other continents extends our area of operation far beyond the borders of Austria and Germany. Working together with strong partners, we are pursuing a clear goal: to design, build and operate construction projects in a way that protects the climate and conserves resources. 

Further information at www.strabag.com.
Visit our newsroom at newsroom.strabag.com.

About Ed. Züblin AG
Stuttgart-based Ed. Züblin AG, with approximately 16,000 employees and an annual output of around € 4.6 billion, is one of Germany’s largest construction companies. ZÜBLIN, which has been successfully realising challenging construction projects in Germany and abroad since 1898, is the STRABAG Group’s leading brand for building construction and civil engineering. The range of services covers all construction-related tasks – from complex turnkey construction, civil engineering and tunnelling to construction logistics, structural maintenance, ground engineering and timber and steel construction. Supported by the expertise of its Zentrale Technik competence centre, ZÜBLIN also offers integrated design-and-build services from a single source. We take an end-to-end view of buildings over their entire life cycle, with a focus on collaborative construction using our TEAMCONCEPT® partnering model while constantly promoting and advancing the topics of digitalisation, sustainability and innovation. Together within the STRABAG Group and with our external partners, we are working systematically to make the design-and-build processes resource-friendly and climateneutral.

Further information at www.zueblin.de.
Visit our newsroom at newsroom.strabag.com.

Media Contacts:

Marianne Jakl
STRABAG SE
Head of Corporate Communications
Group Spokeswoman
+43 1 22422 1174
pr@strabag.com

Marco Reiter
Head of Investor Relations
+43 1 22422 1089
marco.reiter@strabag.com

SOURCE: STRABAG SE