This article reports progress on the 300 million pound Second Severn Crossing between England and Wales. Almost two years after its start, the four-year construction programme is well up to schedule. More than half of the 37 precast concrete caissons, supporting the 5km long structure, have been placed in the Severn estuary. This process is closely followed by pier construction. The first of over 2000 viaduct deck units have been placed; they will edge out from each shore towards the central cable-stayed span. The critical point in the marine works is the transfer of the precast caissons from the shore to the crane barges, which has to be done during seven-day tide 'windows'. A caisson weighs up to 2000t, and is placed every 17 days, but reinforcement fixing and concrete filling takes ten weeks. Piers are then constructed on caissons with the help of pier starter units. Contractor Laing-GTM uses a proven viaduct erection system, balanced cantilevers using glued segmental construction. Because of the two years of detailed planning preceding the start of construction in April 1992, the complex erection sequence is now generally 'routine'. Success depends on good engineering and a thorough understanding of estuary tides and weather.

  • Availability:
  • Corporate Authors:

    Thomas Telford Limited

    London,   United Kingdom 
  • Authors:
    • PARKER, D
  • Publication Date: 1994-3-17


  • English

Media Info

  • Pagination: p. 20-3
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00668072
  • Record Type: Publication
  • Source Agency: Transport Research Laboratory
  • Files: ITRD
  • Created Date: Nov 2 1994 12:00AM