A Study on Highway Capacity and Level of Service for Geometric Design Considering Traffic Operational Conditions

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(1) Analysis on the level of service on multilane highways and its influencing factors.Realized speeds and capacities under various geometric and traffic flow conditions were investigated and geometric, influencing factors to them were extensively analyzed. By using vehicle detector data on intercity, urban expressways and highways, speed-flow relationships were identified corresponding to such various conditions as gradient, heavy vehicle ratio and weather conditions.(2) Analysis on the measure of effectiveness on two-way two-lane highways.The follower density was found to be most suitable measure of effectiveness for two-lane highways where passing behavior is difficult to be performed. In order to appropriately estimate the follower density, judgment criteria of the follower condition were investigated by using raw pulse data of vehicle detectors. A methodology to probabilistically identify followers by using both of headway and speed of individual vehicles were proposed. This methodology can identify followers more reasonable than a conventional methodology which uses a fixed headway value only as a threshold.(3) Analysis on level of service on arterial streetsAn estimation model for delays caused by stops at signalized intersections was developed, in order to estimate travel speeds of arterial street sections which includes several signalized intersections on a planning stage. This model considers such parameters as demand ratios at entries of intersections, traffic, signal coordinations and cycle lengths, which can roughly be assumed at the planning stage. This model was validated at three arterial sections and found to be reliable enough for the purpose of performance check at the planning stage of arterial streets.