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Metro Nuremberg U3 South-West, BA 1.1, BW 338,339,340

It was imperative to extend the Underground railway line 3 to further develop the inner-urban traffic network and to link up new residential areas in the south-west of the City of Nuremberg. The Nuremberg Transport Authority VAG also has the intention of saving costs through an “automatically controlled transport system"- a scheme that is so far unique in Germany. Starting with mixed services involving driver and driverless rolling stock, Lines 2 and 3 are to operate fully automatically by July 2007. BW 340 was driven towards the east to the existing Underground Station "Rothenburger Straße" from a 220 m long excavation pit, which was later to become the "Sündersbühl" Station, in the form of 2 separate tunnel tubes. This section totalling 1,427 m was driven by mining means. Each tube possesses an emergency exit at depths of 15 and 20 m. Practically all of this section of the system runs beneath existing inner-urban buildings. In addition, the southern tube passes beneath the existing Underground tubes of Line 2-at a gap of no more than 50 cm. The subsoil consists of fills and quaternary sands, deconsolidated keuper zones right up to hard sandstones of high strength. The groundwater table is located some 2.50 to 6.50 m below the surface of the terrain so that it influenced the entire excavation as drainage from the surface is only possible in the cut-and-cover section. Up to 30 l/s of water could enter the drive calling for corresponding precautionary measures. BW 338 was driven towards the west starting with 2 individual tubes from the station excavation pit.  After roughly 70 m, the 2 single tubes converge into a twin tube over a switch zone extending some 300 m. At the end of the twin tubes, 2 short single tubes produce the link with the "Gustav-Adolf-Platz" Underground Station. A roadheader was used to drive these tunnel tubes. Supporting was undertaken by means of reinforced dry shotcrete, lattice arches and roof bolts. On account of the small excavated cross-section and the size of the roadheader, all supporting operations including drilling the bolts (drill set up on frame) had to be carried out manually. A watertight concrete permanent lining was selected for the tunnels, with the concrete floors being tackled in advance. The vault concrete was placed by means of the reinforcement and vault formwork carriage that travelled along the floor. Conventional formwork units were used to produce the 2 emergency exits. A mass-spring system was installed as a noise absorbing element towards this end, 20 m long and 1 m thick elements were concreted on the spot, raised and set down on spring elements. Concreting Operations at the "Sündersbühl" Station were started up parallel to the drive towards the west.

 

  • Country: Germany
  • Region: Nuremberg, Bavaria
  • Tunnel utilization: Traffic
  • Type of utilization: Underground, urban and rapid transit
  • Client: City of Nurernberg
  • Consulting Engineer: Köhler+Seitz
  • Construction Monitoring: Foundation Engineering Office/Underground Construction Nurernberg
  • Contractor: Hochtief Construction AG
  • Main construction method: Trenchless
  • Type of excavation: Roadheader
  • Lining: Concrete formwork
  • No. of tubes: 1
  • Tunnel total length: BW 338: two single-track tunnel tubes, each 100 m long 300 m two-track tunnel tube; BW 339: 220 m station built by cut-and-cover; BW 340: two 686 m and 741 m long Singletracktunnel tubes
  • Cross-section: 35 m² single-track tunnel tubes, 56 m² twin-track tunnel tubes
  • Contract Volume: approx. € 29 million
  • Construction start/end: October 2001 to August 2004
  • Opening: 2004