IMPROVED CRITERIA FOR TRAFFIC SIGNAL SYSTEMS ON URBAN ARTERIALS

RESEARCH WAS CONDUCTED ON THE DEVELOPMENT AND COMPREHENSIVE, CLOSELY CONTROLLED, SCIENTIFIC TESTING OF SEVERAL ADVANCED CONCEPTS FOR OPERATING TRAFFIC-SIGNAL SYSTEMS ON URBAN ARTERIAL STREETS. THE RESULTS INDICATE THE DEGREE OF SIGNIFICANT IMPROVEMENT IN TRAFFIC OPERATION POSSIBLE THROUGH APPLICATION OF ADVANCED CONTROL METHODS. USING ESTABLISHED TRAFFIC-SIMULATION METHODS, A TOTAL OF 11 ALTERNATIVE SIGNAL-OPERATION TEST CONDITIONS IN A PILOT STUDY ARTERIAL SYSTEM WERE THOROUGHLY EVALUATED. SUBJECTED TO TESTS WERE FOUR STRATEGIC (FIXED-TIME) CONTROL CONCEPTS APPLIED IN VARIOUS COMBINATIONS, ONE TRAFFIC-ADJUSTED CONTROL CONCEPT, ONE EXPERIMENTAL TRAFFIC-RESPONSIVE CONCEPT, AND ONE SPECIAL MIXED-CYCLE VERSION OF A STRATEGIC CONTROL CONCEPT. A TOTAL OF 100 HOURS OF TRAFFIC OPERATION WERE SIMULATED TO PRODUCE STATISTICALLY RELIABLE RESULTS IN CONJUNCTION WITH THE EFFECTIVENESS TESTS OF ALTERNATIVES. THE MOST INFLUENTIAL STRATEGIC CONTROL CONCEPT TESTED WAS WEBSTER'S STRAIGHTFORWARD COMPUTATIONAL METHOD FOR OPTIMIZING TRAFFIC SIGNAL CYCLE AND SPLITS. THREE COMPUTER-ASSISTED METHODS FOR FORMULATING SIGNAL OFFSET PLANES WERE TESTED: THE YARDENI TIME-SPACE DESIGN MODEL, THE LITTLE MAXIMAL BANDWIDTH MODEL, AND THE DELAY/DIFFERENCE-OF-OFFSET METHOD. ALL THREE OFFSET METHODS PRODUCED STATISTICALLY SIGNIFICANT IMPROVEMENTS IN OPERATIONAL EFFECTIVENESS WHEN APPLIED IN COMBINATION WITH THE WEBSTER TECHNIQUE. HOWEVER, THE SAME THREE OFFSET CONCEPTS GENERALLY FAILED TO PRODUCE STATISTICALLY SIGNIFICANT IMPROVEMENTS WHEN APPLIED INDEPENDENTLY. THE RESEARCH INDICATED THAT THE TRAFFIC-ADJUSTED CONTROL CONCEPT, THE COMMONLY USED CYCLE AND OFFSET SELECTION MODE, REDUCES DELAYS IN THE PILOT SYSTEM BY 39% UNDER OFF-PEAK CONDITIONS AND BY 12% DURING A PEAK HOUR. THE EXPERIMENTAL TRAFFIC-RESPONSIVE CONTROL CONCEPT, THE BASIC QUEUE-CONTROL MODE TESTED IN PRIOR RESEARCH FOR ISOLATED INTERSECTIONS, PRODUCES 20% AND 22% REDUCTIONS IN DELAY DURING THE OFF-PEAK AND PEAK PERIODS, RESPECTIVELY, IN THE SIGNALIZED ARTERIAL SYSTEM. THE SPECIAL VERSION OF STRATEGIC (FIXED-TIME) CONTROL, THE MIXED-CYCLE MODE WHEREIN THE CYCLE LENGTH USED AT MINOR INTERSECTIONS IS SHORTER THAN THAT USED AT THE CRITICAL INTERSECTION, WAS THE MOST EFFECTIVE PEAK-PERIOD TECHNIQUE TESTED. TOTAL DELAY IN THE PILOT SYSTEM IS REDUCED BY 24% USING THIS METHOD DURING THE PEAK HOUR. RESEARCH RESULTS ALSO PRESENT INFORMATION THAT IS FUNDAMENTAL TO COST-BENEFIT ANALYSES OF MAJOR TRAFFIC-CONTROL IMPROVEMENT PROJECTS.

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    • Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the Transportation Research Board of the National Academy of Sciences. Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Copyright © National Academy of Sciences. All rights reserved. No 73, 55 PP, 38 FIGS, 17 TAB, 7 APP, 79 REF
  • Authors:
    • Wagner, F A
    • Gerlough, D L
    • Barnes, F C
  • Publication Date: 1969

Media Info

  • Media Type: Digital/other
  • Serial:
    • NCHRP Report
    • Issue Number: 73
    • Publisher: Transportation Research Board
    • ISSN: 0077-5614
  • Publication flags:

    Open Access (libre)

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  • Accession Number: 00225577
  • Record Type: Publication
  • Files: TRIS, ATRI
  • Created Date: Dec 29 1994 12:00AM