A RECOMMENDED CLEARANCE INTERVAL SIGNAL INDICATION FOR PROTECTED LEFT TURNS

THIS RESEARCH WAS AN EFFORT TO DEVELOP A STANDARD CLEARANCE INTERVAL INDICATION, USING A SINGLE SIGNAL HEAD, FOR THE SITUATION WHERE A PROTECTED LEFT TURN MOVEMENT AT AN INTERSECTION IS TO BE TERMINATED WHILE THE STRAIGHT-THROUGH MOVEMENT CONTINUES. FROM A QUESTIONNAIRE SURVEY OF TRAFFIC ENGINEERS IT WAS FOUND THAT A VARIETY OF LEFT TURN SIGNAL INDICATIONS ARE BEING USED THROUGHOUT THE COUNTRY. LABORATORY AND FIELD STUDIES WERE CONDUCTED TO STUDY DRIVER RESPONSE TO DIFFERENT SIGNALS. STUDY CONCLUSIONS ARE GIVEN AND RECOMMENDATIONS MADE.