路网宏观基本图中磁滞现象的产生机理

Hysteresis Phenomenon in a Macroscopic Fundamental Diagram of Roadway Network

为尽快将路网宏观基本图理论应用于实际交通管控中,利用车流波动理论从交通流状态演化的角度分析路网宏观基本图中磁滞现象的产生机理。以日本京都市的实际观测数据验证部分结论的可靠性。通过理论研究及案例分析发现:1)路网中低密度、高流量的交通流状态经过拥堵流状态后转化为低密度、低流量的交通流状态是磁滞现象产生的重要原因;2)在相同路网车辆数的条件下,相较形成过程,磁滞环的消除过程会使得路网中产生更多的拥堵路段及拥堵溢出点;3)当路网中存在非拥堵路段可供逐渐增加的车辆选择时,路网宏观基本图有可能在磁滞环形成过程中出现路网车辆数持续增加、但路网总流量保持不变的奇异现象。

To better apply the theory of macroscopic fundamental diagram(MFD)to traffic management and control,this paper analyzes the formation mechanism of hysteresis phenomenon in a macroscopic fundamental diagram using traffic flow wave theory.The paper verifies the reliability of partial conclusions using the detector data of urban roadway network in Kyoto.Based on the theoretical analysis and case study,the paper highlights the following findings:1)the translation from traffic flow state with high volume and low density to the flow state with low volume and low density caused by congestion is a primary issue to generate the hysteresis phenomenon;2)in comparison to the loading process(upper curve)of the loop,more congested links and queue-spill over exist in the recovery process(lower curve)under the same traffic volume;3)if the roadway network can supply uncongested links for the increasing users,during the loading process of the loop,the phenomenon that the transportation production maintains a certain level while the traffic volume may increases.