ABSTRACT
The second trunk line project in Munich is a key factor to relieve commuter traffic in Bavaria’s capital. The existing trunk line collects incoming trains from all directions in one tunnel that runs from east to west through the center of the city. The new tunnel will double the capacity to avoid congestions. Three new stations will be built, the deepest of which is the Marienhof station, situated directly behind Munich’s city hall. At a depth of 40m, it will be the deepest regional train station in Germany. Via access tunnels, which will be excavated under compressed air, it will connect to the existing subway network. The large platform tunnels extending the east and west of the central access will also be driven under compressed air. With a section of 430m² it will be one of the most challenging underground operations ever executed in Munich. Further challenging tasks are the extensive lowering of water table by installing more than 100 wells in the city center, and the compensation grouting to reduce settlements of the neighboring historic buildings and the nearby subway tunnels. The paper focuses on the experiences so far and the future challenges of the project.
