This article describes a new tunnel widening technique that allows traffic to continue to flow during construction work. The technique is being used to widen the Nazzano road tunnel in Italy from two to three lanes, with additional emergency lanes in each direction. . A steel traffic protection shell, situated above the traffic and lined with sound proofing and anti-shock materials, allows the tunnel to remain operational during construction. Primary features of the technique include using a segmental final lining to stabilize the widened tunnel that is put into place according to the "active arch principle" that becomes operational at a distance of 4m-5m from the widening face. Because of this technique, passive stabilization operations such as shotcrete and steel ribs are not needed. If necessary, ground improvement can be taken care of ahead of the widening. The article describes where the new widening technique originated, its three stages of construction, how the technique is being used at the Nazzano tunnel, and the benefits of using the technique.

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  • Corporate Authors:

    Polygon Media Limited

    Tubs Hill House, London Road
    Sevenoaks, Kent TN13 1BY,   United Kingdom 
  • Authors:
    • Lunardi, P I
  • Publication Date: 2003-7


  • English

Media Info

  • Features: Figures; Photos; References;
  • Pagination: p. 16-19
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00962290
  • Record Type: Publication
  • Source Agency: UC Berkeley Transportation Library
  • Files: BTRIS, TRIS
  • Created Date: Sep 2 2003 12:00AM