Deutsche Bahn breaks ground on controversial Pfaffenstein Tunnel despite fierce opposition

Deutsche Bahn has initiated construction on the Pfaffenstein Tunnel, a crucial element of the federal rail infrastructure plan. This nearly 11-kilometre tunnel will connect the Gäu Railway to Stuttgart Airport and the future underground station as part of the Stuttgart 21 project. Critics, however, contend that the project's management costs and risks surpass its benefits.

Preparatory work on the tunnel began on 9 February, with initial earthworks now underway north of Stuttgart Airport. Two tunnel boring machines will subsequently excavate through solid rock to complete the structure. Once finished, the tunnel is anticipated to reduce travel times between Stuttgart and Zurich by around 15 minutes.

The project has encountered robust opposition from the Pro Gäu Railway Alliance. The group has labelled the plans a 'declaration of bankruptcy for transport policy', questioning the cost-benefit ratio and cautioning about potential budget overruns. Instead, they advocate for expanding the existing Gäu Railway to two tracks, asserting that this would be a more cost-effective solution.

Debate over the Gäu Railway and Stuttgart-Zurich connections has intensified in recent years. In 2021, Switzerland suspended funding for the 'Zurich–Stuttgart' project, including upgrades to the Gäu Railway, leading to tensions between the two countries. Germany responded by advancing smaller bilateral projects, such as the electrification of the Stuttgart–Herrenberg line, completed in 2024, and upgrades to the Eglisau tunnel. Meanwhile, public campaigns and political pressure from the CDU/CSU in 2023–2025 pushed for full high-speed upgrades, despite costs exceeding €2 billion.

The alliance also warns of risks to the international north-south rail corridor. They emphasize possible service disruptions during construction, which could impact both passenger and freight traffic.

The Pfaffenstein Tunnel remains a divisive project, with Deutsche Bahn progressing despite criticism. If completed as planned, it will enhance travel times between Stuttgart and Zurich. However, concerns over costs, delays, and operational disruptions continue to shape the debate.