NOTES ON FREEWAY CAPACITY

A DISCUSSION OF OPERATING CHARACTERISTICS ON RURAL FREEWAYS AT VOLUMES LESS THAN CAPACITY WHICH WILL RESULT IN A LEVEL OF SERVICE IS GIVEN. BOTH DESIGN CAPACITY AND POSSIBLE CAPACITY OF A UNIFORM SEGMENT OF AN URBAN FREEWAY ARE THEN DISCUSSED. THE GENERAL PROCEDURE DETERMINED FOR CHECKING WEAVING AND MERGING IS' 1/ ESTABLISH A GIVEN GEOMETRIC CONDITION, 2/ ESTIMATE VOLUMES THE VARIOUS TRAFFIC MOVEMENTS, 3/ VOLUME DETERMINATION BY USE OF DISTRIBUTION BY LANE OF ONE-WAY THROUGH TRAFFIC AND PERCENTAGE DISTRIBUTION OF ON-AND OFF-RAMP TRAFFIC IN RIGHT LANE AND AUXILIARY LANE, 4/ AVERAGE VOLUME PER LANE ACROSS ALL LANES SHOULD NOT EXCEED 1800 PER LANE, AND 5/ NUMBER OF WEAVING VEHICLES IN ANY 500-FT SEGMENT SHOULD NOT EXCEED 2100 VPH. THE ANALYSIS OF INTERCHANGE CAPACITY IS ESSENTIALLY THE ANALYSIS OF CONDITIONS AT RAMP TERMINALS.