In a DOT-HETA funded research project evidence has been collected on the occurrence of peak spreading in the UK during the last decade, in terms of the flattening of the three hour peak profile between 07.00 h and 10.00 h AM or between 16.00 h and 19.00 h PM. Three different and complementary sources have been investigated: a) a review of existing data from published literature and lesser known material; b) an analysis on long-term DOT Nationwide Core Census sites, mainly on motorways and on some all-purpose roads; and c) an assessment of ten years of count data in the Greater Manchester area. All material indicates that during the past ten years peak spreading has occurred in many urban areas, but also on interurban roads. The amount of peak spreading depends on the level of congestion, the direction of flow, and has generally been greater in the AM period than in the PM. A distinction can be made between congestion-driven peak spreading and an underlying change in peak profiles caused by socio-economic changes, such as flexible time and part-time work. International studies confirm that peak contraction may occur as a result of a reduction in congestion, through the opening of new infrastructure or decreasing demand. All evidence supports the need properly to represent changing peak profiles in highway scheme appraisal. A number of model approaches are proposed, which are then evaluated in a separate paper, "Advice on the modelling of changes in peak profiles for road scheme appraisal" (see IRRD 880183). For the covering abstract see IRRD 880168.


  • English

Media Info

  • Features: References;
  • Pagination: p. 151-63

Subject/Index Terms

Filing Info

  • Accession Number: 00724205
  • Record Type: Publication
  • Source Agency: Transport Research Laboratory
  • ISBN: 0-86050-283-X
  • Files: ITRD
  • Created Date: Aug 19 1996 12:00AM