CLEARANCE INTERVAL AT TRAFFIC SIGNALS

A PILOT STUDY WAS UNDERTAKEN TO IDENTIFY PROMISING MODIFICATIONS OF AMBER PERIOD DURATION, TRANSVERSE PAVEMENT MARKINGS, AND SUPPLEMENTAL ADVANCED SIGNING THAT GAVE EVIDENCE OF IMPROVEMENTS OF SAFE OPERATIONS AT SIGNALIZED INTERSECTIONS. THE DILEMMA ZONE PROBLEM FOR MINIMUM AMBER PERIODS WAS EXTENSIVELY RESEARCHED. IT WAS FOUND THAT INCREASING THE AMBER PHASE AT AN URBAN LOCATION FROM 3 TO 5 SECONDS INCREASED THE PERCENTAGE OF MOTORISTS OPERATING IN AN UNSAFE OR UNEXPECTED MANNER. INCREASING THE AMBER PHASE AT THE RURAL LOCATION FROM 5 TO 7 SECONDS DECREASED THE PERCENTAGE OF MOTORISTS OPERATING IN AN UNSAFE OR UNEXPECTED MANNER. HOWEVER, IT WAS FOUND THAT THE INSTALLATION OF EXPERIMENTAL TRANSVERSE PAVEMENT MARKINGS AT THE URBAN LOCATION SLIGHTLY DECREASED THE PERCENTAGES OF MOTORISTS OPERATING IN AN UNSAFE OR UNEXPECTED MANNER. ALSO, THE INSTALLATION OF EXPERIMENTAL TRANSVERSE PAVEMENT MARKINGS AT THE RURAL LOCATION INCREASED THE PERCENTAGE OF MOTORISTS OPERATING IN AN UNSAFE OR UNEXPECTED MANNER. /AUTHOR/