CAPACITIES AND CHARACTERISTICS OF RAMP-FREEWAY CONNECTIONS

THE NATIONWIDE FREEWAY RAMP CAPACITY STUDY OBSERVED TRAFFIC VOLUMES AND SPEEDS ON RAMPS AND BY FREEWAY LANES IN CONTINUOUS 5-MIN INCREMENTS AT THE NOSE OF ON- AND OFF-RAMPS . SIMULTANEOUSLY, TRAFFIC FLOW CONDITIONS AND OPERATIONS AT ADJACENT RAMPS WERE ALSO OBSERVED AND DESCRIBED. THIS INITIAL DATA, THE BASIS OF THIS REPORT, WAS ANALYZED ON A 15-MIN FREE FLOW PERIOD, AN ONE HOUR FREE FLOW PERIOD, AND THE PEAK HOUR PERIOD. MERGING AND DIVERGING CAPACITIES OF VARIOUS RAMP TYPES, RAMP-LANE ONE RATIOS RELATED TO MERGING AND DIVERGING CAPACITIES, FREEWAY LANE DISTRIBUTION AT RAMP JUNCTIONS, TWO-LANE RAMP OPERATION, AND EFFECT OF COMMERCIAL VEHICLES ON CAPACITY ARE SOME OF THE TOPICS COVERED. GEOMETRICS SUCH AS ANGLES OF CONVERGENCE AND DIVERGENCE, SIGHT DISTANCE, AND LENGTH OF SPEED-CHANGE LANES ARE EXAMINED IN RELATION TO FREE FLOW MERGING AND DIVERGING. SHORT-TERM PEAKING WITHIN THE PEAK HOUR WAS FOUND TO BE RELATED TO CITY AND METROPOLITAN AREA POPULATION.