PEAK PERIOD ANALYSIS AND CONTROL OF A FREEWAY SYSTEM /WITH DISCUSSION/

PEAK PERIOD FREEWAY CONTROL TECHNIQUES ARE DISCUSSED. A METHOD IS PRESENTED WHICH INVOLVES THE USE OF TOTAL FLOW /IN ONE DIRECTION/ WHICH MUST BE MAINTAINED AT LEVELS LESS THAN OR EQUAL TO THE CAPACITY AT EACH FREEWAY BOTTLENECK. THIS CONTROL HAS GREAT POTENTIAL BECAUSE THE USE OF TOTAL FLOW ACROSS ALL FREEWAY LANES PERMITS USE OF THE CONTINUITY CHARACTERISTICS OF TRAFFIC FLOW, THEREBY MAKING SYSTEM CONSIDERATIONS POSSIBLE. EACH LOCAL CONTROLLER OBTAINS THE DESIRED MERGE RATE FROM THE CENTRAL COMPUTER AND THEN DETERMINES THE TIME HEADWAYS BETWEEN ENTERING VEHICLES TO MAINTAIN THIS RATE OF MERGE. THE CENTRAL COMPUTER MONITORS THE FREEWAY OPERATION BY EXAMINING THE DETECTOR OUTPUTS. IT DETERMINES WHETHER NORMAL OR REDUCED CAPACITY OPERATIONS PREVAIL AND ESTABLISHES THE PROPER MERGING RATES AT EACH ENTRANCE RAMP IN THE SYSTEM. IT SUPPLIES THESE RATES TO THE LOCAL CONTROLLERS WHICH THEN MAINTAINS THEM.