SCHEDULING OF TRAFFIC SIGNALS BY LINEAR PROGRAMMING

THE POSSIBILITIES OF USING LINEAR PROGRAMMING TECHNIQUES FIND THE OPTIMUM TIME PHASING OF TRAFFIC LIGHTS ALONG ONE STREET OR IN A NETWORK OF STREETS ARE INVESTIGATED. TWO EXAMPLES ARE FORMULATED AND SOLVED AS LINEAR PROGRAMMING PROBLEMS. CONSIDERATION IS NEXT MADE OF THE MATHEMATICAL FORMULATION OF A REALISTIC STREET-NETWORK SYSTEM. THE PARAMETERS ASSUMED KNOWN ARE: (1) TOTAL CYCLE TIME, RED PLUS GREEN; (2) THE FRACTION OF THE CYCLE THAT IS RED AT EACH INTERSECTION; AND (3) THE MAXIMUM NUMBER OF VEHICLES MOVING THROUGH THE INTERSECTION IN EACH DIRECTION. THE MODEL CAN HANDLE SUCH PHENOMENA AS (A) VARIATIONS IN AVERAGE SPEED ALONG DIFFERENT PORTIONS OF THE ROUTE, (B) TURN-ONS AND TURN-OFFS, (C) VARIATIONS IN TRAFFIC CAPACITIES WITH INTERSECTION AND FLOW DIRECTION, (D) THE CAPACITY OF BLOCKS FOR HOLDING STOPPED VEHICLES, (E) THREE-WAY LIGHTS OR OTHER SPECIAL LIGHT SCHEDULES, (F) DELAYS IN STARTING AFTER THE LIGHT TURNS GREEN, AND (G) RANDOM DELAYS. THE CRITERION FOR OBTAINING AN OPTIMUM TIME-PHASING OF THE LIGHTS IS THAT THE NUMBER OF DELAYS BE MINIMIZED. IT IS CONCLUDED THAT THE LINEAR PROGRAMMING METHOD IS A POWERFUL TOOL FOR SOLVING THE GENERAL TRAFFIC SCHEDULING PROBLEM BECAUSE OF THE GREAT AMOUNT OF DETAIL THAT CAN BE HANDLED. HOWEVER, THIS CREATES A VERY LARGE PROBLEM EVEN FOR HIGH-SPEED ELECTRONIC COMPUTERS. THUS, CONSIDERABLE EFFORT WILL HAVE TO BE EXPENDED TO SIMPLIFY THE MATHEMATICS AND THE COMPUTING PROCEDURES TO REDUCE THE PROBLEM TO MANAGEABLE SIZE. /AUTHOR/

  • Supplemental Notes:
    • Vol 35, pp 534-542, 7 REF
  • Authors:
    • La, VALLEE RS
  • Publication Date: 1956

Media Info

  • Monograph Title: Proceedings of the Thirty-Fifth Annual Meeting of the Highway Research Board, Washington, D.C., January 17-20, 1956
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00226013
  • Record Type: Publication
  • Files: TRIS, TRB
  • Created Date: Aug 15 1971 12:00AM