Skip navigation

Main Line Tunnel Berlin, Lot 3, Shield Heading

Crossing the city in a north-south direction in Berlin's central area is an important task in developing its rail links. A 3.5 km long tunnel is being built towards this end. For creating the tunnel, various construction methods are applied:

  • in the Lehrter Bahnhof area, passing beneath the Spree and the future Potsdamer Platz regional station, the tunnels are built by cut-and-cover
  • in 2, altogether 1.27 km long sections, in each case 4 single- track tubes are driven and provided with a single-shell watertight lining of reinforced concrete segments
  • the 230 m long ramp structure to the south of the Landwehr Canal with a 4-track cross-section was constructed by the caisson method.

Both boulder clay as well as clays, fine sands, medium sands and gravels are found in the subsurface along the shield heading section. Stone intrusions must be reckoned with. The groundwater level is located roughly 3 m beneath the surface and cannot be lowered for ecological reasons during the entire construction measure. On account of the described geological and hydrogeological conditions, two 705 and 574 m long sections of the main line tunnel have to be driven using a shield. The longer, northern section runs from the Platz der Republik below the Tiergarten up until the Linne-Dreieck to the north of the future regional station at Potsdamer Platz (shield heading 1); the shorter, southern section runs from the junction below the Landwehr Canal to the southern part of the new regional Station at Potsdamer Platz (shield heading 2). The main line tunnel here comprises 4 parallel tubes with 8.93 m external and 7.85 m internal diameter. The total length of the shield driven part-sections amounts to approx. 5 km. On account of this length and the aspired short construction period, 2 heading installations are applied simultaneously. The mix-shield operates using a fluid-supported face. In this way, it is assured that the groundwater is not adversely affected during tunnelling. The machine that is used possesses a rock crusher so that stones can be crushed and removed from the working chamber. The cutting wheel has star shaped spokes for removing the largely soft grounds with cutting knives and roller bits for processing rock. In order to avoid the cutting wheel centre clogging when penetrating the clay and marl layers, a central cutter is attached, which is equipped with its own flushing and conveyance system. The cutting wheel is located in an articulated bearing and can be moved in a longitudinal direction so that overcutting can take place eccentrically, which facilitates the accuracy of the shield passage. The 8 tunnel tubes are provided with a single-shell lining of reinforced concrete segments. The individual tunnel rings constitute 7 block segments and a wedge-shaped key-stone. The reinforced concrete prefabricated parts are made of strength class B 45 watertight concrete. The ring and longitudinal joints of the single-shell tunnel lining are sealed with a neoprene tape to prevent groundwater intruding. On average, the segments are 1.50 m wide, 3.80 m long, 40 cm thick and way more than 5 t.

 

  • Country: Germany
  • Region: Berlin
  • Tunnel utilization: Traffic
  • Type of utilization: Main-line rail
  • Client: Bundesrepublik Deutschland, Land Berlin, Deutsche Bahn AG
  • Main construction method: Trenchless
  • Type of excavation: Shield machine (SM)
  • Lining: Reinforced concrete segments
  • No. of tubes: 4
  • Tunnel total length: 3.5 km
  • Outer diameter: 8.93 m
  • Inner diameter: 7.85 m
  • Construction start/end: 1995 till 2004