PLANNING AND ITS IMPORTANCE IN REDUCING THE COST OF URBAN TUNNELS

Planners can significantly increase the utilization of underground space for transportation, water, sewage, and utility services through better understanding of the effect of geology and construction depth on the cost of underground construction. Planners should realize that construction in soft, near-surface soil in many urban areas is first expensive and second requires underpinning of existing structures, utility relocation, and restoration of city street activities that can cost more than the original tunnel. On the other hand, planners should realize that competent rock exists at reasonable depths under most urban areas in which tunnel boring machines or even conventional drill and blast methods can be used to advance relatively economical tunnels at very fast rates. Such deep tunnels in rock do not require the relocation of utilities, the underpinning of structures or street restoration. Moreover, vertical access to deep tunnels in good construction materials is not prohibitive in cost and can be made to be acceptable to the public. For example, access to a 50 M deep tunnel is equivalent to vertical access via an express elevator to the 14th story of a high rise building. Cost estimates of underground tunnelling in a typical urban area such as Chicago have shown that the basic cost of construction of a cut-and-cover tunnel is in the order of $13400/M, while the cost of an equivalent tunnel in rock below the surface is in the order of $3800/M. The cost for the vertical access to the deep tunnel is more than offset by the highly variable cost of underpinning, utility relocation and restoration which can more than double the cost of shallow tunnels. Clearly, the economics of deep tunnels to provide urban services points to an innovative alternative for providing underground space under U.S. urban areas.

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  • Corporate Authors:

    Pergamon Press, Incorporated

    Headington Hill Hall
    Oxford OX30BW,   England 

    Pergamon Press, Incorporated

    Maxwell House, Fairview Park
    Elmsford, NY  United States  10523
  • Authors:
    • SILVER, M L
    • Peters, J F
  • Publication Date: 1977-12

Media Info

  • Features: Figures; References; Tables;
  • Pagination: p. 65-79
  • Serial:
    • Underground Space
    • Volume: 2
    • Issue Number: 2
    • Publisher: Pergamon Press, Incorporated
    • ISSN: 0362-0565

Subject/Index Terms

Filing Info

  • Accession Number: 00174021
  • Record Type: Publication
  • Source Agency: Transport and Road Research Laboratory (TRRL)
  • Report/Paper Numbers: Analytic
  • Files: ITRD, TRIS
  • Created Date: May 3 1982 12:00AM