This paper compares and assesses tunnel excavation by tunnel boring machines (TBMs) and drill+blast, on the basis of historical and current practice. Although tunnel boring is used for over 90% of civil tunnel excavation in North America and is being used for an increasing proportion of tunnels worldwide, it is still not widely used in many parts of the world. Several factors have prevented its more extensive application: (1) the presence of hard rock; (2) low quality rock masses and soil conditions; (3) plentiful cheap labour; and (4) its longer lead times. Several technological advances are outlined, which enable TBMs to operate in places where their use would previously have been considered unlikely. The two main grounds for comparing the use of TBMs with drill+blast are: (1) excavation costs; and (2) stability and safety at the excavation face. Both these aspects are considered in some detail. In general, TBM excavation can save significant costs by using it high excavation rates to eliminate the need for temporary construction structures. It provides only significant additional advantages at high progress rates, but these advantages are only marginal at low progress rates.

  • Availability:
  • Corporate Authors:

    Morgan-Grampian Limited

    30 Calderwood Street
    London SE18 6QH,   England 
  • Authors:
    • TARKOY, P J
  • Publication Date: 1995-10


  • English

Media Info

  • Features: References;
  • Pagination: p. 41-4
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00717984
  • Record Type: Publication
  • Source Agency: Transport Research Laboratory
  • Files: ITRD
  • Created Date: Mar 20 1996 12:00AM