To determine the dynamic influence range of emergencies under special events, the spacial and temporal characteristics of the traffic flow are studied by simulation based on the cell transmission model （CTM）. Based ...To determine the dynamic influence range of emergencies under special events, the spacial and temporal characteristics of the traffic flow are studied by simulation based on the cell transmission model （CTM）. Based on the traffic management measures used under special events, a semi-dynamic assignment algorithm is proposed, which is combined with an algorithm for logit multi-path traffic assignment and the CTM. In a simple calculation network, the spacial and temporal characteristics of traffic flows which vary with different traffic management schemes are studied, and a method to obtain the influence range of emergency is proposed by computing the jam time of the intersections. By contrasting the average delay of each vehicle, the dissipation effect is studied under two different traffic management schemes. The example shows that the spatial and temporal variety of the traffic flow can be easily simulated and the influence range of emergency can be confirmed by the method based on the CTM. The proposed method provides a new idea for decision-making on traffic management under emergency under special events.展开更多
This paper integrates the maximum information principle with the Cell Transmission Model （CTM） to formulate the velocity distribution evolution of vehicle traffic flow. The proposed discrete traffic kinetic model us...This paper integrates the maximum information principle with the Cell Transmission Model （CTM） to formulate the velocity distribution evolution of vehicle traffic flow. The proposed discrete traffic kinetic model uses the cell transmission model to calculate the macroscopic variables of the vehicle transmission, and the maximum information principle to examine the velocity distribution in each cell. The velocity distribution based on maximum information principle is solved by the Lagrange multiplier method. The advantage of the proposed model is that it can simultaneously calculate the hydrodynamic variables and velocity distribution at the cell level. An example shows how the proposed model works. The proposed model is a hybrid traffic simulation model, which can be used to understand the self-organization phenomena in traffic flows and predict the traffic evolution.展开更多
This paper describes a location specific cell transmission model of freeway traffic based on the observed variability of fundamental diagrams both along and across freeway segments. This model extends the original cel...This paper describes a location specific cell transmission model of freeway traffic based on the observed variability of fundamental diagrams both along and across freeway segments. This model extends the original cell transmission model （CTM） mechanism by defining various shapes of fundamental diagrams to reproduce more complex traffic phenomena, including capacity drops, lane-by-lane variations, nonho- mogeneous wave propagation velocities, and temporal lags. A field test on a Canadian freeway was used to demonstrate the validity of the location specific CTM. The simulated spatio-temporal evolutions of traffic flow show that the model can be used to describe the traffic dynamics near bottlenecks more precisely than the original model.展开更多
为调整不同路段的限速值,平滑交通流,从而提升高速公路车辆通行的安全性和效率,针对交通瓶颈区设计一种基于深度强化学习的平滑车速管控系统。该系统主要包含动态限速启动、限速值确定与更新和情报板动态发布等3个模块。将深度强化学习...为调整不同路段的限速值,平滑交通流,从而提升高速公路车辆通行的安全性和效率,针对交通瓶颈区设计一种基于深度强化学习的平滑车速管控系统。该系统主要包含动态限速启动、限速值确定与更新和情报板动态发布等3个模块。将深度强化学习算法DDQN(Double Deep Q-Network)引入系统中,提出一种基于DDQN的平滑车速控制策略,从目标网络和经验回顾2个维度提升该算法的性能。基于元胞传输模型(Cellular Transmission Model,CTM)对宁夏高速公路某路段的交通流运行场景进行仿真,以车辆总通行时间和车流量为评价指标验证该系统的有效性,结果表明该系统能提高瓶颈区内拥堵路段车辆的通行效率。展开更多
Advanced information and communication technolo-gies can be used to facilitate traffic incident management.If an incident is detected and blocks a road link,in order to reduce the incident-induced traffic congestion,a...Advanced information and communication technolo-gies can be used to facilitate traffic incident management.If an incident is detected and blocks a road link,in order to reduce the incident-induced traffic congestion,a dynamic strategy to deliver incident information to selected drivers and help them make detours in urban areas is proposed by this work.Time-dependent shortest path algorithms are used to generate a subnetwork where vehicles should receive such information.A simulation approach based on an extended cell transmission model is used to describe traffic flow in urban networks where path information and traffic flow at downstream road links are well modeled.Simulation results reveal the influences of some major parameters of an incident-induced congestion dissipation process such as the ratio of route-changing vehicles to the total vehicles,operation time interval of the proposed strategy,traffic density in the traffic network,and the scope of the area where traffic incident information is delivered.The results can be used to improve the state of the art in preventing urban road traffic congestion caused by incidents.展开更多
基金The National High Technology Research and Development Program of China(863 Program)(No.2007AA11Z210)
文摘To determine the dynamic influence range of emergencies under special events, the spacial and temporal characteristics of the traffic flow are studied by simulation based on the cell transmission model （CTM）. Based on the traffic management measures used under special events, a semi-dynamic assignment algorithm is proposed, which is combined with an algorithm for logit multi-path traffic assignment and the CTM. In a simple calculation network, the spacial and temporal characteristics of traffic flows which vary with different traffic management schemes are studied, and a method to obtain the influence range of emergency is proposed by computing the jam time of the intersections. By contrasting the average delay of each vehicle, the dissipation effect is studied under two different traffic management schemes. The example shows that the spatial and temporal variety of the traffic flow can be easily simulated and the influence range of emergency can be confirmed by the method based on the CTM. The proposed method provides a new idea for decision-making on traffic management under emergency under special events.
基金Project supported by the National Natural Science Foundation of China(Grant No.71071024)the Hunan Provincial Natural Science Foundation(Grant No.12JJ2025)
文摘This paper integrates the maximum information principle with the Cell Transmission Model （CTM） to formulate the velocity distribution evolution of vehicle traffic flow. The proposed discrete traffic kinetic model uses the cell transmission model to calculate the macroscopic variables of the vehicle transmission, and the maximum information principle to examine the velocity distribution in each cell. The velocity distribution based on maximum information principle is solved by the Lagrange multiplier method. The advantage of the proposed model is that it can simultaneously calculate the hydrodynamic variables and velocity distribution at the cell level. An example shows how the proposed model works. The proposed model is a hybrid traffic simulation model, which can be used to understand the self-organization phenomena in traffic flows and predict the traffic evolution.
基金Supported in part by the National Key Basic Research and Devel-opment (973) Program of China (No. 2006CB705506)the National Natural Science Foundation of China (No. 50708055)+1 种基金the Key Technologies Research & Development Program of the Eleventh Five-Year Plan of China (No. 2007BAK35B06)the Scientific Research Foundation for the Returned Overseas Chinese Scholars,Ministry of Education
文摘This paper describes a location specific cell transmission model of freeway traffic based on the observed variability of fundamental diagrams both along and across freeway segments. This model extends the original cell transmission model （CTM） mechanism by defining various shapes of fundamental diagrams to reproduce more complex traffic phenomena, including capacity drops, lane-by-lane variations, nonho- mogeneous wave propagation velocities, and temporal lags. A field test on a Canadian freeway was used to demonstrate the validity of the location specific CTM. The simulated spatio-temporal evolutions of traffic flow show that the model can be used to describe the traffic dynamics near bottlenecks more precisely than the original model.
文摘为调整不同路段的限速值,平滑交通流,从而提升高速公路车辆通行的安全性和效率,针对交通瓶颈区设计一种基于深度强化学习的平滑车速管控系统。该系统主要包含动态限速启动、限速值确定与更新和情报板动态发布等3个模块。将深度强化学习算法DDQN(Double Deep Q-Network)引入系统中,提出一种基于DDQN的平滑车速控制策略,从目标网络和经验回顾2个维度提升该算法的性能。基于元胞传输模型(Cellular Transmission Model,CTM)对宁夏高速公路某路段的交通流运行场景进行仿真,以车辆总通行时间和车流量为评价指标验证该系统的有效性,结果表明该系统能提高瓶颈区内拥堵路段车辆的通行效率。
基金supported by the National Natural Science Foundation of China(61374148)
文摘Advanced information and communication technolo-gies can be used to facilitate traffic incident management.If an incident is detected and blocks a road link,in order to reduce the incident-induced traffic congestion,a dynamic strategy to deliver incident information to selected drivers and help them make detours in urban areas is proposed by this work.Time-dependent shortest path algorithms are used to generate a subnetwork where vehicles should receive such information.A simulation approach based on an extended cell transmission model is used to describe traffic flow in urban networks where path information and traffic flow at downstream road links are well modeled.Simulation results reveal the influences of some major parameters of an incident-induced congestion dissipation process such as the ratio of route-changing vehicles to the total vehicles,operation time interval of the proposed strategy,traffic density in the traffic network,and the scope of the area where traffic incident information is delivered.The results can be used to improve the state of the art in preventing urban road traffic congestion caused by incidents.
