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

(1)多车道公路服务水平及其影响因素分析研究了不同几何条件和交通流条件下的通行速度和通行能力，并对其几何影响因素进行了深入的分析。通过使用城际、城市快速路和高速公路上的车辆检测器数据，识别出与坡度、重型车辆比例和天气条件等不同条件对应的速度-流量关系。(2)双向双车道高速公路有效性度量分析，发现对于难以通过行为的双车道高速公路，追随者密度是最合适的有效性度量。为了合理估计跟随器的密度，利用车辆探测器的原始脉冲数据，研究了跟随器条件的判断准则。提出了一种同时利用单车车头距和车速概率识别跟随者的方法。主干道服务水平分析为了在规划阶段对包含多个信号交叉口的主干道路段的通行速度进行估计，建立了信号交叉口停车延误的估计模型。该模型考虑了交叉口入口的需求比、交通流量、信号协调和周期长度等参数，这些参数可以在规划阶段大致假设。该模型在三个主干道路段上进行了验证，结果表明，该模型对于主干道规划阶段的性能考核是足够可靠的。

(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.