Traffic flow of a roundabout crossing with an open boundary condition

This paper presents a cellular automaton traffic flow model with an open boundary condition to describe the traffic flow at a roundabout crossing with an inner roundabout lane and an outer roundabout lane. The simulation results show that the boundary condition, bottlenecks and the self-organization affect the traffic flow at the roundabout crossing. Because of the effect of bottlenecks, jams easily appear on the inner roundabout lane. To improve the capacity of the roundabout system, proper values of the enter probability α and the out probability $\beta $ can be chosen.     

Traffic Modelling for Moving-Block Train Control System

This paper presents a new cellular automaton （CA） model for train control system simulation. In the proposed CA model, the driver reactions to train movements are captured by some updated rules. The space-time diagram of traffic flow and the trajectory of train movement is used to obtain insight into the characteristic behavior of railway traffic flow. A number of simulation results demonstrate that the proposed CA model can be successfully used for the simulations of railway traffic. Not only the characteristic behavior of railway traffic flow can be reproduced, but also the simulation values of the minimum time headway are close to the theoretical values.     

Study on the Reduced Traffic Congestion Method Based on Dynamic Guidance Information

This paper studies how to generate the reasonable information of travelers' decision in real network. This problem is very complex because the travelers' decision is constrained by different human behavior. The network conditions can be predicted by using the advanced dynamic OD(Origin-Destination, OD) estimation techniques. Based on the improved mesoscopic traffic model, the predictable dynamic traffic guidance information can be obtained accurately.A consistency algorithm is designed to investigate the travelers' decision by simulating the dynamic response to guidance information. The simulation results show that the proposed method can provide the best guidance information. Further,a case study is conducted to verify the theoretical results and to draw managerial insights into the potential of dynamic guidance strategy in improving traffic performance.     

公交车停靠诱发交通瓶颈的元胞自动机模拟

利用双车道元胞自动机模型,研究公交车停靠对道路混合交通流的影响.针对港湾式和非港湾式两种不同公交车站设置,在开放边界下模拟了公交车停靠所产生的交通瓶颈问题,给出了车辆入流概率-公交车比例相平面上的相图,区分了自由流相和拥挤相,研究了相图各区中公交车站附近的平均密度和速度分布图,比较了两种公交车站情况下的道路交通流的动力学特征.研究发现,当公交车比例较小时,与非港湾式车站相比,港湾式车站可以显著改善车站处的交通状况. 关键词： 元胞自动机 混合交通流 交通瓶颈 公交车站     

城市快速路系统的元胞自动机模型与分析

使用元胞自动机模型研究包含出入匝、主路和辅路的城市快速路系统的交通问题,为不同类型的路段定义了三种不同的换道规则.模拟结果表明,高入匝流量容易导致主路、匝道及其上游出现拥堵,高出匝流量容易使匝道出口车流与辅路内侧道车流发生冲突.入匝流量比较高时,主辅路为双车道的系统可以延缓交通拥堵和减少通行时间;当入匝流量较低时,双车道改善了单车道下辅路的通行状况. 关键词： 交通流 元胞自动机 换道规则 匝道     

One-Dimensional Traffic Model to Consider Priority of the Stochastic Deceleration

A one-dimensional cellular automaton model of traffic flow is proposed to introduce the different delay probabilities in the steps of rules and the stochastic deceleration prior to the deterministic one when the anticipation velocity of vehicle is larger than the headway. The fundamental diagram shows the capacity of road more approaches to the observed data compared with that by the NaSch model. Moreover, the model is able to reproduce the complicated behavior of the real traffic, such as the metastability state, the separation of different phases and the effect of hysteresis. It is concluded that the order arrangement of the stochastic deceleration and deterministic acceleration has indeed remarkable effect on traffic flow and the modification presented in this paper is reasonable and realistic.     

Cellular Automaton Models of Highway Traffic Flow Considering Lane-Control and Speed-Control

As two kinds of management modes of highway traffic control, lane-control, and speed-control produce different effect under different conditions. In this paper, traffic flow cellular automaton models for four-lane highway system with two opposing directions under the above two modes are established considering car and truck mixed running. Through computer numerical simulating, the fundamental diagrams with different parameters are obtained, and after the analysis of density-flux diagrams, the variation discipline of flux with traffic density under different control models is gained. The results indicate that, compared with lane-control, utilization ratio of road can be further improved with speed-control when the truck number increases. The research result is of great significance for reasonable providing theoretical guidance for highway traffic control.     

速度限制对交通流的影响

运用元胞自动机模型研究单车道路面上设立限速区对交通流的影响.计算机模拟结果显示,在交通流与密度的基本图中存在饱和交通流量,其大小取决于限速区的最大速度.限速区的设立导致不同相的分离.在确定性的模型中,当车辆密度较低时,存在两种不同的自由流相;而当车辆密度较高时,出现最大交通流相和自由流相.在随机模型中,车辆密度较高时,出现最大交通流相-堵塞相-自由流.对交通流以及临界密度等量给出一些解析结果.     

A Cellular Automaton Model for Heterogeneous and Incosistent Driver Behavior in Urban Traffic

In this paper a cellular automaton model is proposed to describe driver behavior at a single-lane urban roundabout. Driver behavior has been considered as heterogeneous and inconsistent. Most traffic papers in the literature just discussed heterogeneous driver behavior, to our best knowledge. Two truncated Gaussian distributions are used to model heterogeneous and inconsistent driver behavior, respectively. The physical meanings of two truncated distributions are indicated. This method may help enhance a better understanding of driver behavior at roundabout traffic, and even possibly provide references for roundabout design and management.     

Combined bottleneck effect of on-ramp and bus stop in a cellular automaton model

The combined bottleneck effect is investigated by modeling traffic systems with an on-ramp and a nearby bus stop in a two-lane cellular automaton model. Two cases, i.e. the bus stop locates in the downstream section of the on-ramp and the bus stop locates in the upstream section of the on-ramp, are considered separately. The upstream flux and downstream flux of the main road, as well as the on-ramp flux are analysed in detail, with respect to the entering probabilities and the distance between the on-ramp and the bus stop. It is found that the combination of the two bottlenecks causes the capacity to drop off, because the vehicles entering the main road from the on-ramp would interweave with the stopping (pulling-out) buses in the downstream (upstream) case. The traffic conflict in the former case is much heavier than that in the latter, causing the downstream main road to be utilized inefficiently. This suggests that the bus stop should be set in the upstream section of the on-ramp to enhance the capacity. The fluxes both on the main road and on the on-ramp vary with the distance between the two bottlenecks in both cases. However, the effects of distance disappear gradually at large distances. These findings might give some guidance to traffic optimization and management.     

地铁站内交织行人流的简化模型和数值模拟

地铁站内多方向行人流以不同方式通过瓶颈时具有不同的效率,发生拥堵的机制也有所不同. 本文将地铁站内行人流的交织运动简化为连通双通道内两股行人通过瓶颈的情形. 采用推广的格子气模型,通过引入背景场,使改进的模型可以刻画地铁站内行人流的运动特征, 通过数值模拟研究了两股行人以两种不同方式经过研究区域的清空时间以及瓶颈宽度的影响. 研究发现,在模型中考虑行人沿对角线的运动可以更加准确地描述真实行人运动. 当瓶颈宽度小于临界宽度时,逆向交织的行人经过研究区域具有更高的效率, 验证了行人流实验的结果.此外还详细讨论了在瓶颈处发生拥堵的机理.     

开放性边界条件下双车道元胞自动机交通流模型耦合效应研究

在一种改进的Nagel-Schrekenberg元胞自动机交通流模型的基础上，提出一个高速公路双车 道元胞自动机模型来模拟开放性边界条件下的车流运动，并考虑两车道之间左边界开放程度 的比例系数α及车辆加减速概率p的影响.计算机数值模拟结果表明，在车流状态的演化过程 中，通过确定车道耦合系数b来控制车流量，不同的b值车流量不同，对车辆运动出现堵塞项 的相变点有影响. 关键词： 元胞自动机 交通流模型 耦合效应     

Traffic dynamics of an on-ramp system with a cellular automaton model

This paper uses the cellular automaton model to study the dynamics of traffic flow around an on-ramp with an acceleration lane. It adopts a parameter, which can reflect different lane-changing behaviour, to represent the diversity of driving behaviour. The refined cellular automaton model is used to describe the lower acceleration rate of a vehicle. The phase diagram and the capacity of the on-ramp system are investigated. The simulation results show that in the single cell model, the capacity of the on-ramp system will stay at the highest flow of a one lane system when the driver is moderate and careful; it will be reduced when the driver is aggressive. In the refined cellular automaton model, the capacity is always reduced even when the driver is careful. It proposes that the capacity drop of the on-ramp system is caused by aggressive lane-changing behaviour and lower acceleration rate.     

A Cellular Automaton Model for Heterogeneous and Incosistent Driver Behavior in Urban Traffic

In this paper a cellular automaton model is proposed to describe driver behavior at a single-lane urban roundabout. Driver behavior has been considered as heterogeneous and inconsistent. Most traffic papers in the literature just discussed heterogeneous driver behavior, to our best knowledge. Two truncated Gaussian distributions are used to model heterogeneous and inconsistent driver behavior, respectively. The physical meanings of two truncated distributions are indicated. This method may help enhance a better understanding of driver behavior at roundabout traffic, and even possibly provide references for roundabout design and management.     

Instantaneous information propagation in free flow, synchronized flow, stop-and-go waves in a cellular automaton model

Recently, a number of efforts are underway to investigate inter-vehicle communications （IVC）. This paper studies the instantaneous information propagation behaviours based on IVC in three different tragic situations （free flow, synchronized flow and stop-and-go waves） in a cellular automaton model. It is shown that different behaviours appear in stop-and-go waves from those in free flow and synchronized flow. While the distribution of Multi-hop Communication Distance （MhCD） is either exponential or uniform in free flow and synchronized flow, the distribution of MhCD is either exponential or with a single peak in stop-and-go waves.     

交通灯控制下主干道的交通流研究

用元胞自动机模型模拟二维交通流.通过交叉口设置的红绿灯，研究交通激波的形成和传播 ；对于一定的红绿灯周期，交通流量出现多个极值现象；在交叉口间隔相同的情况下，对于 一定的红绿灯周期，在一定的车辆密度范围内，交通流量是一个与密度无关的常量；在车辆 密度较高的情况下，交叉口间距大于某一值后，交通流量保持恒定值. 关键词： 元胞自动机模型 交通流 交通激波     

交通灯控制下城市主干道双车道多速元胞自动机交通流模型研究

提出一个城市主干道双车道多速元胞自动机交通流模型，此模型采用开放性 边界条件，在考虑诸多实际因素影响情况下，研究了主干道中车站的设置、交通灯绿信比对 车流量和车流速度的影响.计算机模拟所得到的基本图（流量 速度图）能较好地反映在交 通灯控制下城市主干道交通流真实状况. 关键词： 元胞自动机模型 交通流 主干道