The 5-year construction period for the first Dartford tunnel is contrasted with progress made since June 1972 with the second crossing. The risk to health, and the expense of using compressed air as formerly at 248 kn/m2 led to the decision to use air at 138 kn/m2 this time. It was also decided to construct 550 M of the 1435 M between portals by cut and cover method, the remainder of the tunnel being driven through heavily grouted ground. Grout mixtures were adjusted to penetrate the fine fissures. Inflow of water during construction has necessitated use of air pressure exceeding 200 kn/m2. The lack of progress due to difficult labour relations is discussed. Cover plates over joints in the concrete and steel lining are not watertight and voids have to be filled by injecting resin. The magnitude of this work cannot be forecast, and the total cost of the tunnel may exceed found36 M. (TRRL)

Media Info

  • Features: Photos;
  • Pagination: p. 16-18
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00311746
  • Record Type: Publication
  • Source Agency: Transport Research Laboratory
  • Files: ITRD, TRIS
  • Created Date: Oct 27 1980 12:00AM