New Vienna Tunnel Project Worth €2.7 Billion

Austria’s Ministry of Transport has announced plans to advance the Lobau Tunnel (S1) project — a large-scale infrastructure initiative designed to ease traffic congestion in Vienna. The proposed 8.2-km tunnel, passing 60 meters beneath the Danube River, aims to divert heavy truck traffic from entering the city and improve road safety for urban commuters.

The total S1 route will stretch 19 km with two lanes in each direction. The estimated cost of the entire project stands at €2.7 billion.

The first construction stage — a new interchange connection with the main motorway network — is expected to start in 2026, financed by the state-owned road operator Asfinag, with an investment of €500 million. If final approval for the Lobau Tunnel is granted, major tunneling works could begin in 2030.

Controversy and Environmental Concerns.

The project has sparked strong opposition from environmental groups, as the planned route runs under the Lobau National Park (2,300 hectares), part of the Danube-Auen National Park and the UNESCO Biosphere Reserve.

The Austrian Green Party filed a lawsuit that halted construction in 2021, citing risks to ecosystems and increased emissions from traffic. The Ministry insists that the tunnel, located deep underground, would leave the surface ecosystem intact. Nevertheless, environmentalists warn that construction activities and rising vehicle volumes may still disturb the sensitive wetland environment.

The Lobau Tunnel was chosen over an earlier bridge option proposed in 2001, which was rejected partly for ecological reasons.

Comment by the Institute of Danube Research :

“The Lobau Tunnel highlights the fundamental dilemma of modern Danube-region urban planning — balancing mobility and ecological integrity.
For Ukraine and its Danube cities (Odesa, Izmail, Reni), the case underscores the importance of conducting strategic environmental assessments and public consultations at early stages of planning major transport corridors.
Sustainable development in the Danube basin must prioritize both connectivity and nature conservation.”