A further treatment of opposed turning movements in traffic signal calculations

The saturation flow of opposed turning movements at intersection traffic signals shows great variation during a signal cycle. The value can attain 1800 veh/h per lane when there is no opposing flow of vehicles or pedestrians but can be almost zero when the opposing flows are continuous. The variation is usually due to the use of a late start or an early cut off of the opposing flow, so that there are opportunities for the opposed flow both during the green period of the opposing flow and during the late start or early cut off periods. The usual methods of calculating signal timings require a single value of saturation flow. This paper shows how to convert the varying saturation flow to an effective single value using the concept of an extra effective green time. The procedure in the subsequent calculations is still iterative but converges rapidly. The solution is correct for the practical spare capacity and a good approximation for average delay. The method can be applied to opposed right or left turning and even to an experimental left turn on red indication.


  • English

Media Info

  • Pagination: 1-Jul
  • Serial:
    • Volume: 10
    • Issue Number: 4

Subject/Index Terms

Filing Info

  • Accession Number: 01439182
  • Record Type: Publication
  • Source Agency: ARRB
  • Files: ATRI
  • Created Date: Aug 24 2012 10:04PM