INTERSECTION DELAY AND LEFT TURN PHASING

OVER THE PAST TEN YEARS THE ROAD DEPARTMENT AND OTHER AGENCIES IN LOS ANGELES COUNTY HAVE INSTALLED MINOR MOVEMENT LEFT TURN PHASING AT NUMEROUS SIGNALIZED INTERSECTIONS. WHEN TRAFFIC VOLUMES AT SIGNALIZED INTERSECTIONS INCREASE, THE PROBLEM OF PROVIDING LEFT TURN PROTECTION SIMILARLY INCREASES. THREE LOCATIONS ARE ANALYZED AFTER DELAY STUDIES ARE USED TO FIND HOW MUCH INTERSECTION DELAY INCREASED AFTER LEFT TURN PHASING WAS INSTALLED. CONCLUSIONS INDICATED THAT: (1) INTERSECTION DELAY PER VEHICLE SUBSTANTIALLY INCREASED FROM 22% TO 121% AFTER LEFT PHASING WAS INSTALLED, (2) PEAK HOUR DELAY MAY INCREASE OVER 100% AFTER LEFT TURN PHASING IS INSTALLED ON ALL APPROACHES OF THE INTERSECTION, (3) LEFT TURN DELAY IS NOT SUBSTANTIALLY REDUCED BY LEFT TURN PHASING, AND (4) NORMALLY, INTERSECTION DELAY COSTS OUTWEIGH ACCIDENT REDUCTION SAVINGS, BUT ACCIDENT SAVINGS SHOULD BE CONSIDERED FOR EACH INDIVIDUAL INTERSECTION. /AUTHOR/

• Supplemental Notes:
  • Vol 39, No 9, PP 50-53
• Authors:
  • Gurnett, G
• Publication Date: 1969-6

Media Info

• Serial:
  • Traffic Engineering, Inst Traffic Engr

Subject/Index Terms

• TRT Terms: Intersections; Left turns; Prevention; Safety; Traffic crashes; Traffic delays; Traffic volume
• Old TRIS Terms: Phase control
• Subject Areas: Highways; Operations and Traffic Management; Safety and Human Factors; Security and Emergencies;

Filing Info

• Accession Number: 00225528
• Record Type: Publication
• Files: TRIS
• Created Date: Nov 11 1994 12:00AM