My Take (Arnulf Christa): The Pfaffensteigtunnel shows a familiar pattern: major railway projects in Germany regularly underestimate costs, in this case by 800 million euros more than planned. For general contractors like STRABAG and ZÜBLIN it becomes interesting because independent experts estimate costs at 3.5 to 4 billion euros.
On 12 October 2026, the Pfaffensteigtunnel in Stuttgart was ceremonially broken ground in the presence of Federal Transport Minister Steffen Bilger, State Transport Minister Nicole Razavi, and Deutsche Bahn board chair Evelyn Palla. The Infrastructure Plan 2026 now allocates €2.5 billion to the tunnel construction—a significant increase from the original federal budget of €1.7 billion. This €800 million cost escalation has prompted sharp criticism from environmental and transport policy advocates.
The Deutsche Umwelthilfe has called for an immediate construction halt, citing concerns not only about cost overruns but also about the structural adequacy of Stuttgart’s underground main station. Independent cost analysts already estimate real expenditure at €3.5–4 billion. The project is being delivered by DB InfraGO AG with federal funding, with consortium partners STRABAG and ZÜBLIN supported by an alliance of specialist firms including FCP, Geoconsult, Hörmann, iC-Consulenten, Rhomberg Bahntechnik, Spitzke, Swietelsky, and Wayss & Freytag under an integrated project alliance model.
Construction commenced in February 2026 with scheduled completion in December 2033. The tunnel forms a critical element of the Stuttgart–Ulm rail corridor expansion and the broader Stuttgart 21 programme, which has become emblematic of cost inflation in major German transport infrastructure.
Source: Bahnprojekt Stuttgart–Ulm