This article reports on the Swiss experience of large tunnel boring machines (TBMs). Since 1970, ten two-lane rail and road tunnels, with diameters greater than 10m and a total length of about 35km, have been built in Switzerland using large TBMs. The diameters of these TBMs vary from 10.8m to 11.9m. Hitherto, two general types of TBM have been used in Switzerland: (1) full face TBMs, which excavate the final tunnel face in one stage; (2) tunnel enlargement machines, which excavate it in two or three stages. The latter are especially economical in self-supporting rock or in ground with little rock breakout. Factors affecting TBM efficiency include: (1) the work plan; (2) the geology; (3) machine type; (4) boring system and several other specific factors affecting operations. For enlarging machines, the effort spent on rock support must also be considered. Typical causes of major TBM performance problems on the projects discussed here can be classified into: (1) machine-specific and operational; and (2) due to geological complications. The most important conclusions are expressed by the gross advance rates achieved. These include the following: (1) 2.6km per year for full face TBMs with shield, based on four completed tunnels; and (2) 1.9km per year for tunnel enlargement machines, based on experience of three commissioned tunnels. The projects discussed here have contributed to the development of modern tunnelling methods during the past 25 years.

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  • Corporate Authors:

    Morgan-Grampian (Construction Press) Limited

    Morgan-Grampian House, 30 Calderwood Street
    London SE18 6QH,   England 
  • Authors:
    • Kovari, K
    • AMSTAD, C
    • FECHTIG, R
  • Publication Date: 1993-12


  • English

Media Info

  • Features: References;
  • Pagination: p. 23-6
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00662545
  • Record Type: Publication
  • Source Agency: Transport Research Laboratory
  • Files: ITRD
  • Created Date: Jul 28 1994 12:00AM