The author discusses methods of bridge widening using a steel and composite method to construct clear spans of up to 45m resulting in minimum conflict with the road user. The three options open for the arrangement of the new carriageway are known as symmetric, asymmetric and parallel widening. The differences are in the new land required to extend the carriageway, whether a narrow strip on each side, or just sufficient width to one side or a wider strip to allow for lateral displacement. In the case of parallel widening, one carriageway is built on new ground, and a strip of former carriageway becomes a soft verge or landscape area. There is reduced conflict between construction work on the substructures and traffic with this method, but twin spans are required with a new intermediate support close to an existing hard shoulder. A further hard shoulder is paved over the existing central reserve containing drainage and services. Provisions for future changes without reconstruction are being built into the designs to avoid the need to demolish bridges of age less than 30 years, as is presently experienced in some cases.

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  • Corporate Authors:

    Reed Business Information, Limited

    Quadrant House, The Quadrant
    Brighton Road
    Sutton, Surrey  United Kingdom  SM2 5AS
  • Authors:
    • ILES, D
  • Publication Date: 1993-9-16


  • English

Media Info

  • Features: References;
  • Pagination: p. 36
  • Serial:
    • Volume: 370
    • Issue Number: 5942
    • Publisher: Reed Business Information, Limited
    • ISSN: 0010-7859

Subject/Index Terms

Filing Info

  • Accession Number: 00662433
  • Record Type: Publication
  • Source Agency: Transport Research Laboratory
  • Files: ITRD
  • Created Date: Jul 28 1994 12:00AM