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The tunnel passes through layers of Lower Variegated Marl (km 3) of Middle Keuper. These formations, by and large, consists of sand and clay stone. The sulphate content (gypsum, anhydrite), which was originally present has disappeared from this zone through leaching processes. As a result, the rock character of the bedrock has been lost. The rock has been redistributed, it is faulty and partially filled and can be removed by an excavator. There are also irregularly distributed, locally restricted water-bearing layers. Lot 2: As the leached Lower Variegated Mari had not been penetrated by a tunnel up till that point in time and the rock and the ground in the transition zone appeared to be suitable for a mined tunnel, a pilot tunnel together with a test section was driven. Lot 1: On account of the minimal overburden and the faulted rock (Lower Variegated Mari) this section of the tunnel was executed via cut-and-cover. Lot 2: ln order to be able to master the engineering geologically unfavourable slope and local weakness zones resulting from Ice Age slips, the NATM was selected - as a flexible construction method. Excavators and/or road headers were used for tunnelling. A 25-30 cm thick shotcrete lining was installed as support. The 50 cm thick inner shell of the tunnel was created using watertight reinforced concrete without working joints.


  • Country: Germany
  • Region: Baden-Württemberg
  • Tunnel utilization: Traffic
  • Type of utilization: Main-line rail
  • Client: Deutsche Bahn AG
  • Main construction method: Open/Trenchless
  • Type of excavation: Excavator/Roadheader
  • Lining: Concrete formwork
  • No. of tubes: 1
  • Tunnel total length: 1115 m (including 683 m by cut-and-cover)
  • Cross-section: approx. 165 m²
  • Contract Volume: 42 mill. DM
  • Construction start/end: 1986-1987
  • Opening: 1987