TRAFFIC CHARACTERISTICS FOR IMPLEMENTATION AND CALIBRATION OF FREEWAY MERGING CONTROL SYSTEMS

USING THE GULF FREEWAY IN HOUSTON AS THE LABORATORY, A NUMBER OF TRAFFIC CHARACTERISTICS ASSOCIATED WITH GAP ACCEPTANCE CONTROL WERE STUDIED. DATA COLLECTION WAS PERFORMED USING MANUAL METHODS, A CLOSED-CIRCUIT TELEVISION SYSTEM, AND AN ELECTRONIC DATA ACQUISITION SYSTEM INCLUDING FIELD SENSORS AND A DIGITAL COMPUTER. THE RAMP TRAFFIC CHARACTERISTICS PRESENTED INCLUDE THE VEHICLE PERFORMANCE CHARACTERISTICS OF SPEED, ACCELERATION, AND TRAVEL TIME, THE RELATIONSHIPS AMONG THESE VARIABLES, AND THE EFFECTS OF VEHICLE TYPE AND RAMP GRADE ON THESE VARIABLES. THE BEHAVIOR OF RAMP VEHICLES AT THE CONTROL SIGNAL WAS ALSO STUDIED TO DETERMINE THE STARTING-DELAY CHARACTERISTICS AND STOPPING POSITION OF VEHICLES AT THE RAMP SIGNAL. A FREQUENCY DISTRIBUTION OF EACH VARIABLE IS PRESENTED AND THE APPLICATION OF THE RESULTS IN THE IMPLEMENTATION AND CALIBRATION OF MERGING CONTROL SYSTEMS IS DISCUSSED. SEVERAL FREEWAY TRAFFIC CHARACTERISTICS WERE ALSO STUDIED. THESE WERE CONCERNED MAINLY WITH TRAFFIC STABILITY UPSTREAM FROM AN ENTRANCE RAMP AND THE EFFECT OF THIS STABILITY ON THE ACCURACY WITH WHICH THE TRAJECTORY OF A RAMP VEHICLE CAN BE MATCHED WITH A FREEWAY GAP. ALSO PRESENTED IS THE RELATIONSHIP BETWEEN TOTAL TRAVEL AND TOTAL TRAVEL TIME, TWO MEASURES OF EFFECTIVENESS OFTEN USED IN THE EVALUATION OF FREEWAY CONTROL SYSTEMS. THE POSSIBLE APPLICATION OF THIS RELATIONSHIP IN THE DEVELOPMENT OF WARRANTS FOR FREEWAY CONTROL IS INDICATED. /AUTHOR/