HIGHWAY CAPACITY IN NORTH AMERICA - THE NEW APPROACH

The subject is introduced by tracing capacity in North America from the early measurement of the 1930's through the early capacity manuals to the new manual. The major research efforts since the 65 manual are described. The directed activities and current status to fill voids for the new manual are presented. The process leading to the new highway capacity manual is discussed including schedule, format, contents, and emphasis. Four principal areas where key changes have occurred are presented in detail. The first area described is weaving analyses. Two procedures have evolved -one with a design orientation and the other with an operations orientation. A major research effort is underway to compare the two, to recommend revisions, and to determine optimal use of each. Two-lane rural road procedures have substantially changed. Maximum two-way capacity has increased. Separate analyses are presented for level terrain and for segments on grades. A new level of service parameter, "per cent of time delayed" has been added. The third area discussed is unsignalised intersections. A German methodology applicable to two-way stop and yield intersections has been refined and applied to North American conditions. Concern continues over the applicability at locations where platooned arrivals exist on the major street. The final section discusses the signalized intersection chapter which has changed more than any other area. Two levels of analysis are used -a simplified procedure for general planning estimates and a complex procedure for operations and design purposes. Level of service is based on estimated delay with the computation being a modification of the Australian method. Three different analysis units can be evaluated: individual movements, total approaches, or the overall intersection. The paper concludes with a reiteration of the schedule for the publication of the highway capacity manual. (Author/TRRL)

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  • Supplemental Notes:
    • This paper was presented during the 12th Australian Road Research Board Conference, Hobart, Tasmania, 27-31 August 1984.
  • Corporate Authors:

    ARRB

    Melbourne, Victoria  Australia 
  • Authors:
    • Kell, J H
  • Publication Date: 1984

Media Info

  • Features: Figures; Tables;
  • Pagination: p. 33-43
  • Serial:

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Filing Info

  • Accession Number: 00393408
  • Record Type: Publication
  • Source Agency: ARRB
  • Files: ITRD, TRIS, ATRI
  • Created Date: Jun 30 1985 12:00AM