1956•Highway Research Board ProceedingsRequires access
FIELD MEASUREMENT OF DELAY AT SIGNALIZED INTERSECTIONS
Donald S Berry
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Abstract
METHODS FOR FIELD MEASUREMENT OF INTERSECTION DELAY AND THE EFFECTS OF DIFFERENT SIGNAL TIMING PLANS ON STOPPED-TIME DELAY DURING DAYLIGHT HOURS AT SIGNALIZED INTERSECTIONS IN THE SAN FRANCISCO BAY AREA WERE STUDIED. THREE METHODS FOR MEASURING STOPPED-TIME DELAY WERE COMPARED: (1) THE ITTE DELAY METER, WHICH ACCUMULATES VEHICLE-SECONDS OF STOPPED TIME; (2) A SAMPLING METHOD FOR ESTIMATING VEHICLE-SECONDS OF STOPPED TIME; AND (3) USE OF SPACED SERIAL PHOTOS TO OBTAIN STOPPED TIME AND TRAVEL TIME FOR EACH VEHICLE. ALL THREE METHODS WERE SATISFACTORY FOR OBTAINING STOPPED-TIME DELAY AT SIGNALIZED INTERSECTIONS. THE SPACED SERIAL PHOTO METHOD REQUIRES MORE MANPOWER FOR DATA REDUCTION, BUT IS THE ONLY ONE SUITED FOR TRAVEL-TIME DELAY STUDIES AT SIGNALIZED AND NON-SIGNALIZED INTERSECTIONS. A COMPARISON OF STOPPED-TIME DELAY AT THREE-PHASE SIGNALIZED INTERSECTIONS WITH TRAFFIC-ACTUATED VS. FIXED-TIME CONTROL IS STUDIED. THE ACTUATED TIMING WAS BETTER ABLE TO ACCEPT SHORT-TERM FLUCTUATIONS THAN FIXED-TIME SIGNALS. AT INTERSECTIONS WITH PEDESTRIAN MOVEMENTS, PEDESTRIAN TIMERS PERMITTED TIMING PLANS WHICH SUBSTANTIALLY REDUCED VEHICULAR DELAY. AN OVERLAP SEQUENCE IN THREE-PHASE SIGNALS TIMING WITH HEAVY LEFT-TURN MOVEMENTS FROM ONE DIRECTION REDUCES DELAY IN BOTH PEAK AND OFF-PEAK HOURS. UNNECESSARY DELAY, DEFINED AS THAT PORTION OF STOPPED-TIME DELAY OCCURRING WHEN NO TRAFFIC IS USING THE INTERSECTING STREET IS ALSO STUDIED. UNNECESSARY DELAY WAS SUBSTANTIALLY LOWER WITH ACTUATED THAN WITH FIXED-TIME CONTROL,. STOPPED-TIME DELAYS WERE SUBSTANTIALLY LOWER FOR FULL-ACTUATED CONTROL THAN FOR SEMI-ACTUATED CONTROL. STOPPED-TIME DELAY WAS ALSO STUDIED AT TWO SIGNALIZED INTERSECTION 1,185 FEET APART TO ASCERTAIN THE EFFECT ON DELAY OF COORDINATING THE TIMING OF TWO FIXED-TIME SIGNALS. THE DELAY TO THE MAIN STREET TRAFFIC IN BOTH PEAK AND OFF-PEAK HOURS WAS LESS THAN HALF THE DELAY EXPERIENCED WHEN USING ACTUATE TRAFFIC SIGNAL CONTROL WITHOUT COORDINATION OF THE TIMING OF THE TWO SIGNALS. /AUTHOR/