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Light Rail Stuttgart, Tunnel U2, Steinhaldenfeld

The building of the U 2 tunnel Steinhaldenfeld was part of the ongoing extension of the Stuttgart urban railway network, which has been pursued consistently for decades. Undertaking these major projects and ensuring that they do not cause avoidable nuisance to residents is a particular concern of the Stuttgarter Straßenbahnen AG (SSB AG) and the regional capital of Stuttgart. As a result the construction process was geared to requirements for providing protection against noise, dust and vibrations. A particular and novel challenge was the tunnel's location beneath main cemetery. The altogether 1.090 m long tunnel can be split up into four areas. The access area at the side of the main cemetery was produced by cut-and-cover over a length of 110 m. The tunnel was developed in the twin-track section in which the bulk of the tunnel was driven over a length of 800 m. This was followed by a 70 m long enlargement area as the transition to a further 70 m long cross-section. This was essential on account of the shallow overburden and the geology existing at Steinhaldenfeld. Shell lime, clay keuper and gypsum keuper formations were encountered in the proximity of the tunnel and the stations. Taking the changing geological conditions into consideration the tunnel was excavated using the NATM. The overburden amounted to 10-15 m. During the drive, measurements were continuously taken in order to reduce the effects of settlements by optimising the supporting measures and blasting operations and to restrict the vibrations to an acceptable degree. The subject of vibrations was especially sensitive given the location beneath the main cemetery for many people were concerned that damage could be done to graves. Thanks to a targeted arrangement of measurement points the blasting operation required were optimised in such a way regarding amount of explosives, number and time of the ignitions that there were hardly any complaints. A 60 m long escape gallery had to be additionally driven to the 14 m deep escape stairway so that the latter was not located within the cemetery area. The shaft was also produced by the NATM.


  • Country: Germany
  • Region: Baden-Württemberg
  • Tunnel utilization: Traffic
  • Type of utilization: Underground, urban and rapid transit
  • Client: SSB AG, represented by Stuttgart Foundation Engineering Office
  • Consulting Engineer: Spiekermann GmbH Beratende Ingenieure, Prof. Dr.-Ing. W. Wilke Beratende Ingenieure, Aachen
  • Test engineer: Dr.-Ing. Erichsen (mining construction method), Dipl.-Ing. Rauschning (cut-and-cover method)
  • Construction monitoring: Prof. Dr.-Ing. W. Wilke Beratende Ingenieure, Aachen
  • Contractor: JV Ed. Züblin AG/Strabag AG
  • Main construction method: Trenchless
  • Type of excavation: Drill-and-blast
  • Lining: Shotcrete
  • No. of tubes: 1
  • Tunnel total length: 1,090 m; 110 m (cut-and-cover), 940 m (mining means)
  • Cross-section: 70 m²
  • Contract Volume: 21.5 mill. Euro
  • Construction start/end: 2002 till 2005
  • Opening: 2005