B 2, New 4-Lane Auerberg Tunnel

Short description

The Auerberg Tunnel (L = 1.9 km) consists of two tunnel tubes constructed using shotcrete with inner linings, as well as the associated operational buildings, catch basins, erosion control walls, earthworks, and various restoration measures.

The project

  • Construction of the new B2 between Eschenlohe and Oberau as a 3.8-kilometer-long, four-lane section to improve the connection from the A95 to Garmisch-Partenkirchen.
  • The centerpiece of the project is the 1.9-km-long Auerberg Tunnel, consisting of a west tunnel (1,907 m) and an east tunnel (1,853 m), which are connected by a total of six cross-passages
  • The tunnel will be constructed using blasting methods with shotcrete lining. The excavation volume amounts to approximately 320,000 m³
  • The lining consists of cast-in-place concrete; the portal structures are to be constructed using the open-cut method; in the south, as a gallery structure.
  • In addition, operational buildings with a back-anchored underwater concrete floor, catch basins, and erosion protection walls will be constructed at each portal
  • Extensive earthwork, waste disposal services, and final restoration measures.

Services in detail

  • Tunneling in a horseshoe profile as RQ 31t with a curved and flat floor (A = 85–111 m²)
  • Inner shell: 0.30 m (unreinforced) or 0.35 m (reinforced)
  • Open construction method (OBW) in the north: 26.70 m (east tunnel) + 16.70 m (west tunnel). In the south: 30 m (west tunnel).
    Closed gallery structures south: L = 46.50 m (east) and 40.00 m (west)
  • Construction of the OBW using bored pile foundations. Designed as a WUB-KO with internal block joint sealing, gusset walls at transitions to the closed construction method, dewatering work
  • Shoring work using back-anchored and braced bored-pile walls

Challenges

  • A drinking water tunnel—known as the “Vestbühlstollen”—operated by Stadtwerke München crosses the route at an angle of approximately 44° and will be crossed by the tunnel at a minimum distance of about 6 m from the planned tunnel route

Sustainability

  • Implemented material flow management for all excavated and removed materials, including continuous sampling and testing to determine which materials are suitable for reuse or proper disposal

Further information

  • Construction Supervision: BOL/BÜ Auerberg Tunnel Engineering Consortium, Müller + Hereth / BUNG / IBG
  • Consortium: Implenia Civil Engineering GmbH (TGF), Wayss&Freytag Ingenieurbau AG (KGF), Implenia Austria GmbH
  • Project Website

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