Dynamics is studied for one-dimensional single-lane traffic flow by means of an extended optimal-velocity model with continuously varied bottleneck strength for nonlinear roads. Two phases exist in this model such as ...Dynamics is studied for one-dimensional single-lane traffic flow by means of an extended optimal-velocity model with continuously varied bottleneck strength for nonlinear roads. Two phases exist in this model such as free flow and wide moving jam states in the systems having relatively small values of the bottleneck strength parameter. In addition to the two phases, locally congested phaseappears as the strength becomes prominent. Jam formation occurs with the similar mechanism to the boomerang effect as well as the pinch one in it. Wide scattering of the flow-density relation in fundamental diagram is found in the congested phase.展开更多
A properly designed public transport system is expected to improve traffic efficiency.A high-frequency bus service would decrease the waiting time for passengers,but the interaction between buses and cars might result...A properly designed public transport system is expected to improve traffic efficiency.A high-frequency bus service would decrease the waiting time for passengers,but the interaction between buses and cars might result in more serious congestion.On the other hand,a low-frequency bus service would increase the waiting time for passengers and would not reduce the use of private cars.It is important to strike a balance between high and low frequencies in order to minimize the total delays for all road users.It is critical to formulate the impacts of bus frequency on congestion dynamics and mode choices.However,as far as the authors know,most proposed bus frequency optimization formulations are based on static demand and the Bureau of Public Roads function,and do not properly consider the congestion dynamics and their impacts on mode choices.To fill this gap,this paper proposes a bi-level optimization model.A three-dimensional Macroscopic Fundamental Diagram based modeling approach is developed to capture the bi-modal congestion dynamics.A variational inequality model for the user equilibrium in mode choices is presented and solved using a double projection algorithm.A surrogate model-based algorithm is used to solve the bi-level programming problem.展开更多
In this paper, an extended social force model was applied to investigate fundamental diagrams of pedestrian flows. In the presented model, both the static floor field and the view field were taken into account. Then e...In this paper, an extended social force model was applied to investigate fundamental diagrams of pedestrian flows. In the presented model, both the static floor field and the view field were taken into account. Then each pedestrian can determine his/her desired walking directions according to both global and local information. The fundamental diagrams were obtained numerically under periodic boundary condition. It was found that the fundamental diagrams show good agreement with the measured data in the case of unidirectional flow, especially in the medium density range. However, the fundamental diagram for the case of bidirectional flow gave larger values than the measured data. Furthermore, the bidirectional flux is larger than the tmidirectional flux in a certain density range. It is indicated that the bidirectional flow may be more efficient than the unidirectional flow in some cases. The process of lane formation is quite quick in the model. Typical flow patterns in three scenarios were given to show some realistic applications.展开更多
为了降低交通运输系统能源消耗,同时满足居民的出行需求,需综合考虑机动车燃油消耗和道路通行效率.针对此问题,引入交通网络车均燃油消耗和宏观基本图(Macroscopic Fundamental Diagram,MFD),建立了车辆完成率高、车均燃油消耗低的双目...为了降低交通运输系统能源消耗,同时满足居民的出行需求,需综合考虑机动车燃油消耗和道路通行效率.针对此问题,引入交通网络车均燃油消耗和宏观基本图(Macroscopic Fundamental Diagram,MFD),建立了车辆完成率高、车均燃油消耗低的双目标规划模型,并对模型进行求解.依据反馈原理和车流平衡方程提出了燃油消耗比例积分控制(Fuel Consumption-Proportional Integral,FC-PI)控制方法,并通过FC-PI控制方法降低区域内车均燃油消耗,提高路网车辆完成率.最后通过实际城市路网验证所提出的燃油消耗控制模型,并且与Bang-Bang控制方法进行了比较.仿真结果显示,网络内车均燃油消耗显著降低,同时网络内车辆完成率得到提高,且FC-PI控制方法的控制效果要优于Bang-Bang控制方法.展开更多
文摘Dynamics is studied for one-dimensional single-lane traffic flow by means of an extended optimal-velocity model with continuously varied bottleneck strength for nonlinear roads. Two phases exist in this model such as free flow and wide moving jam states in the systems having relatively small values of the bottleneck strength parameter. In addition to the two phases, locally congested phaseappears as the strength becomes prominent. Jam formation occurs with the similar mechanism to the boomerang effect as well as the pinch one in it. Wide scattering of the flow-density relation in fundamental diagram is found in the congested phase.
基金supported by the National Natural Science Foundation of China(Grant No.72201088,71871077,71925001)the Fundamental Research Funds for the Central Universities of China(Grant No.PA2022GDSK0040,JZ2023YQTD0073),which are gratefully acknowledged.
文摘A properly designed public transport system is expected to improve traffic efficiency.A high-frequency bus service would decrease the waiting time for passengers,but the interaction between buses and cars might result in more serious congestion.On the other hand,a low-frequency bus service would increase the waiting time for passengers and would not reduce the use of private cars.It is important to strike a balance between high and low frequencies in order to minimize the total delays for all road users.It is critical to formulate the impacts of bus frequency on congestion dynamics and mode choices.However,as far as the authors know,most proposed bus frequency optimization formulations are based on static demand and the Bureau of Public Roads function,and do not properly consider the congestion dynamics and their impacts on mode choices.To fill this gap,this paper proposes a bi-level optimization model.A three-dimensional Macroscopic Fundamental Diagram based modeling approach is developed to capture the bi-modal congestion dynamics.A variational inequality model for the user equilibrium in mode choices is presented and solved using a double projection algorithm.A surrogate model-based algorithm is used to solve the bi-level programming problem.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11572184,11562020 and 11172164)the National Basic Research Development Program of China(973 Program,Grant No.2012CB725404)
文摘In this paper, an extended social force model was applied to investigate fundamental diagrams of pedestrian flows. In the presented model, both the static floor field and the view field were taken into account. Then each pedestrian can determine his/her desired walking directions according to both global and local information. The fundamental diagrams were obtained numerically under periodic boundary condition. It was found that the fundamental diagrams show good agreement with the measured data in the case of unidirectional flow, especially in the medium density range. However, the fundamental diagram for the case of bidirectional flow gave larger values than the measured data. Furthermore, the bidirectional flux is larger than the tmidirectional flux in a certain density range. It is indicated that the bidirectional flow may be more efficient than the unidirectional flow in some cases. The process of lane formation is quite quick in the model. Typical flow patterns in three scenarios were given to show some realistic applications.
文摘为了降低交通运输系统能源消耗,同时满足居民的出行需求,需综合考虑机动车燃油消耗和道路通行效率.针对此问题,引入交通网络车均燃油消耗和宏观基本图(Macroscopic Fundamental Diagram,MFD),建立了车辆完成率高、车均燃油消耗低的双目标规划模型,并对模型进行求解.依据反馈原理和车流平衡方程提出了燃油消耗比例积分控制(Fuel Consumption-Proportional Integral,FC-PI)控制方法,并通过FC-PI控制方法降低区域内车均燃油消耗,提高路网车辆完成率.最后通过实际城市路网验证所提出的燃油消耗控制模型,并且与Bang-Bang控制方法进行了比较.仿真结果显示,网络内车均燃油消耗显著降低,同时网络内车辆完成率得到提高,且FC-PI控制方法的控制效果要优于Bang-Bang控制方法.
