TRAFFIC SIGNAL CALCULATIONS IN RELATION TO JUNCTION LAYOUT, CAPACITY AND DELAY

This paper reviews current British procedures for calculations related to traffic signals at individual road junctions. The most commonly used procedures are those described by Webster and Cobbe in Road Research Technical Paper no 56. Other procedures are the computer programs SIGSET and SIGCAP andprograms for finding acceptable sequences of stages, calculating the corresponding minimum cycle times required to pass the given traffic volumes, and a forthcoming procedure for calculating signal timings when there is oversaturation during peak periods. A questionnaire was served to local authorities to find out the extent of signal installations in their areas and the use made of the most widely-available procedures. Interviews were arranged with engineers in many of the areas to find out their attitude to the procedures and to possible changes in them. Comments were also obtained from consulting engineers, signal manufacturers and research workers. It was found that there was some difficulty among engineers in relating timings obtained from procedures based on fixed-time operation to vehicle-actuated signals used in practice. Other principal problems were the treatment of opposed turning traffic and the analysis of a set of very closely-spaced junctions as a single junction, and an indifference to delay as a criterion for signal timing optimisation. Possible new procedures and changes in existing procedures and the research required to develop these are discussed.(a) (TRRL)

  • Availability:
  • Corporate Authors:

    Printerhall Limited

    29 Newmart Street
    London W1P 3PE,   England 
  • Authors:
    • Pretty, R L
  • Publication Date: 1980-3

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Filing Info

  • Accession Number: 00319571
  • Record Type: Publication
  • Source Agency: Transport Research Laboratory
  • Files: ITRD, TRIS
  • Created Date: Feb 6 1981 12:00AM