TWO LANE LEFT TURNS STUDIED AT SIGNALIZED INTERSECTIONS

A STUDY WAS CONDUCTED TO DETERMINE HOW MUCH BENEFIT THE SECOND LANE PROVIDED IN TWO LANE LEFT TURNS AT SIGNALIZED INTERSECTIONS WITH PROTECTED LEFT TURNS CONTROLLED BY GREEN ARROWS. COUNTS WERE COMPARED AT PEAK HOURS AT TWO LANE LEFT TURN INTERSECTIONS AND AT ONE LANE LEFT TURN INTERSECTIONS. IT WAS FOUND THAT EACH LANE IS USED ALMOST EQUALLY WHEN BOTH LANES ARE RESERVED EXCLUSIVELY FOR LEFT TURNS. BUT COMPARED TO THE VOLUME OF THE SINGLE LEFT TURN LANE, THE CAPACITY OF EACH LANE IN THE DOUBLE LEFT TURN LANES WAS REDUCED. HOWEVER , BY ADDING A SECOND LEFT TURN LANE THE CAPACITY INCREASES AT LEAST 75 PERCENT AND THEREFORE REDUCES THE AMOUNT OF GREEN TIME FOR LEFT TURNS, THEREBY REDUCING THE SIGNAL CYCLE LENGTH AND PROVIDING ADDED CAPACITY FOR THE OTHER MOVEMENTS AT THOSE INTERSECTIONS.

• Supplemental Notes:
  • Vol 35, No 7, PP 17-58, 4 TAB
• Authors:
  • Ray, J C
• Publication Date: 1965-4

Media Info

• Serial:
  • Traffic Engineering, Inst Traffic Eng

Subject/Index Terms

• TRT Terms: Crash investigation; Intersections; Left turns; Peak hour traffic; Regulatory signs; Signals; Studies; Traffic counting; Traffic lanes
• Uncontrolled Terms: Capacity
• Old TRIS Terms: Lanes; Left turn only
• Subject Areas: Highways; Operations and Traffic Management; Safety and Human Factors;

Filing Info

• Accession Number: 00225142
• Record Type: Publication
• Files: TRIS
• Created Date: Jun 9 1994 12:00AM