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

This report reviews current British procedures for calculations related to traffic signals at individual road junctions. Some of the procedures apply only to isolated junctions and others apply also to junctions in systems of linked signals. The most commonly used procedures are those described by Webster and Cobbe in Road Research Technical Paper No 56. Other procedures reviewed are the computer programs SIGSET and SIGCAP, and programs for finding acceptable sequences of signal stages, calculating the corresponding minimum cycle times required to pass the given traffic volumes, and 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 signal timings obtained from procedures based on fixed-time operation to those for vehicle-actuated signals used in practice. Other principal problems were a disenchantment with delay as a criterion for signal timing optimisation, the treatment of opposed turning traffic and the analysis of a set of very closely-spaced junctions as a single junction. Possible new procedures and changes in existing procedures and the research required to develop these are discussed. (Author/TRRL)

• Corporate Authors:

  London University, England

  Senate House
  London WC1,   England 
• Authors:
  • Pretty, R L
• Publication Date: 1979-10

Media Info

• Features: Figures; References; Tables;
• Pagination: 37 p.

Subject/Index Terms

• TRT Terms: Computer programs; Highway capacity; Improvements; Information processing; Intersections; Layout; Local government; Local government agencies; Methodology; Optimization; Peak periods; Pretimed traffic signal controllers; Questionnaires; Signalized intersections; Traffic actuated controllers; Traffic delays; Traffic signal control systems; Traffic signal cycle; Traffic signal timing; Traffic signals; Utilization
• Uncontrolled Terms: Criteria; Optimum
• Geographic Terms: United Kingdom
• Old TRIS Terms: Computing; Cycles
• ITRD Terms: 643: Capacity (road, footway); 576: Cycle (traffic signals); 9010: Delay; 9108: Improvement; 9147: Interview; 455: Junction; 2885: Layout; 597: Linked signals; 192: Local authority; 9102: Method; 612: Peak hour; 8645: Software; 565: Traffic signal; 8119: United Kingdom; 557: Vehicle actuated
• Subject Areas: Highways; Operations and Traffic Management; Research; I73: Traffic Control;

Filing Info

• Accession Number: 00330805
• Record Type: Publication
• Source Agency: Transport Research Laboratory
• Report/Paper Numbers: Monograph
• Files: ITRD, TRIS
• Created Date: Aug 15 1981 12:00AM