The Fast Track Beneath the City: City Tunnel Leipzig

Project Background

Leipzig Central Station is Europe’s largest terminal station by surface area. Previously, all trains had to take long detours around the city centre. Since its opening in 2013, the City Tunnel Leipzig has accelerated regional rail transport and significantly reduced travel times across the S-Bahn network – by up to 40 minutes on some routes. With four underground stations, the city centre is now optimally connected to public transport.
 

Our Services

The project is considered one of the most geotechnically demanding construction projects of our time. Our geotechnical experts from across Germany supported the project from the very beginning. We handled the challenges of complex ground conditions successfully for our client, including hard rock formations, lignite deposits, and heavily anthropogenically modified terrain. Obstacles such as high-strength sandstone blocks, remaining retaining walls, and tieback anchors had to be tunnelled through or safely secured in advance using elaborate measures. We prepared all geotechnical and foundation reports, as well as assessments of the hydrogeological impacts of the excavation works, which reached deep into the city’s main groundwater aquifer. In addition, we planned the protection of the tunnelled and adjacent urban structures and infrastructure.
 

The complex geological and hydrogeological conditions along the tunnel alignment posed the highest demands on all project participants.

Grit Renker, Project Manager

Construction in Sensitive Urban Areas

It was particularly important not only to protect historically valuable structures but also to tunnel beneath new buildings without causing damage. In some cases, buildings were tunnelled beneath by the shield machine with an overburden of only 1.5 m. To secure structures at the Museum of Fine Arts, for example, we applied the Compensation Grouting, which involves injecting grout into the foundation area to stabilise and lift the building, compensating for settlements caused by tunnel excavation.
 

Managing Complex Groundwater Conditions

The varying pressure conditions in the different groundwater layers, along with the resulting complex hydraulic flow patterns, added further challenges to the project. Locally limited groundwater relief measures during construction, combined with extensive online groundwater monitoring, minimised risks and ensured the project’s successful completion for our client and the citizens of Leipzig.