Two lane road traffic flow and capacity - chapters 2 to 6, development of the 1965 highway capacity manual procedure

This report represents the first part of a comprehensive review of research and practices related to two lane road traffic flow and capacity analysis. It covers the research background to the 1965 highway capacity manual two lane road analysis procedures, the development of those procedures, and a consideration of their applications and relevance. The development of the concepts of, and numerical values for, traffic capacity and design levels for traffic operations are traced through from the early deliberations of the Highway Research Board committee on traffic analysis to the comprehensive data and methods contained in the 1965 manual. The analysis methods and values given in the capacity manual are based on a comprehensive set of operating speed vs volume characteristics. It is shown that these characteristics were derived from limited empirical relations, using a highly simplified theoretical analysis, and that they are sensitive to a number of unstated assumptions. The truck adjustment factors were also derived from doubtful theoretical considerations. No theoretical or empirical evidence could be found to support the width adjustment factors. It is argued that, while the capacity manual's two lane road analysis procedures may suffice for broad planning purposes, they are inadequate for the detailed consideration of traffic operations necessary to evaluate minor improvement options (a).

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  • Corporate Authors:


    Melbourne, Victoria  Australia 
  • Authors:
    • McLean, J R
  • Publication Date: 1980-12


  • English

Media Info

  • Pagination: 131P
  • Serial:
    • Issue Number: AIR 359-1

Subject/Index Terms

Filing Info

  • Accession Number: 01438524
  • Record Type: Publication
  • Source Agency: ARRB
  • Files: ATRI
  • Created Date: Aug 24 2012 9:36PM