Lainzer Tunnel

The Lainzer Tunnel is a rail tunnel about nine kilometers (5.6 miles) long in Vienna that has connected the western and eastern parts of the city underground since the end of 2012. Named after the Lainz district, the route runs through the Lainzer Tiergarten, among other places, which is why the media also dubbed it the "Wild Boar Tunnel." It was built mainly to relieve the existing Verbindungsbahn and to increase capacity for east-west transit. This laid the groundwork for the direct connection of Vienna's new main station, which replaced Westbahnhof as the central long-distance terminal.

The route begins at the Wolf in der Au commuter rail station, where it links up with the Wienerwald Tunnel, and passes beneath the Wien River. It then crosses the Hietzing district and the ridge formed by Trazerberg, Girzenberg and Roter Berg, before joining the Südbahn line near Meidling and the Donauländebahn near Inzersdorf. As part of the European high-speed corridor Paris–Bratislava–Budapest, the tunnel is built with two tracks. Passenger trains may travel at up to 160 kilometers per hour (100 mph), while freight trains have a top speed of 120 kilometers per hour (75 mph).

The project's history was marked by long planning and construction periods. After it was handed over to Eisenbahn-Hochleistungsstrecken AG in the 1990s, the actual excavation work did not begin until 2006, once legal hurdles had been cleared by the Administrative Court. The breakthrough came in 2009, and regular operation started in 2012. Today, numerous long-distance trains, including Railjets and ICE trains, as well as freight trains use the tunnel every day. After flood damage in 2024, the tracks were repaired and flood protection was improved to ensure uninterrupted operation.