The demand for greater motorway capacity, resulting from the substantial growth in road traffic in the UK, is being met increasingly by plans to widen existing motorways where their traffic congestion is worst. The effect of this demand on bridges is considered, both in the present road construction programme and in the provision for future growth in demand. Careful planning and clear policies are essential to minimise the disruption to traffic caused by a widening programme. Bridges constrain the widening methods that can be used, and many of them need to be demolished and rebuilt, due to their inflexible design. The choice of replacement bridges is related to construction in a live traffic situation but not necessarily to minimum initial cost. The methods of widening are: (1) the symmetrical method, adding equal road width to both carriageways; (2) building a new hard shoulder alongside an existing alignment; (3) asymmetrical widening; and (4) parallel widening, with a new wider carriageway alongside the existing road. Some strategy options are discussed for avoiding premature demolition of bridges in the future, if further widening should later become necessary. Bridges should be designed flexibly, to allow for this possibility. For the covering abstract see IRRD 873097.


  • English

Media Info

  • Features: References;
  • Pagination: p. 1-11

Subject/Index Terms

Filing Info

  • Accession Number: 00712413
  • Record Type: Publication
  • Source Agency: Transport Research Laboratory
  • Files: ITRD
  • Created Date: Oct 24 1995 12:00AM