基于场力的驾驶员影响因素交通流动力学模型

为研究驾驶员行为对道路交通的定量影响,针对驾驶员行为特点,综合考虑了驾驶员受到的直接物理影响和间接心理影响、相对速度以及车辆自身特性等因素,结合场力、图论等方法,提出了一种用于模拟考虑驾驶员影响因素的元胞自动机交通流动力学模型(简称IDCA模型).通过计算机数值模拟,研究了考虑驾驶员影响因素下车流演化机理及不同驾驶员类型对道路交通流的影响.结果表明:与NaSch模型相比,本文建立的IDCA模型能够模拟得到丰富的交通行为,再现了同步流等交通现象,从速度波动和车头间距波动分析得出IDCA模型下道路交通流具有更强的稳定性,堵塞消融效率更高.此外得到了由不同驾驶员类型按不同比例组成的混合交通流的密度-速度图和密度-流量图,发现在道路相同中高密度下,激进型驾驶员所占的比例越大,车辆速度与交通流量越大,交通流量随着保守型驾驶员比例的增加而降低.最后模拟实现了车辆高速跟驰现象,得到小间距高速跟驰率超过7%的结果与实测结果相符合.     

时滞车辆跟驰模型及其分岔现象

交通流车辆跟驰理论中, 由于生理因素, 造成司机在处理前方车辆变化信息和采取应对措施之间存在时间滞后. 即使是在自动巡航控制系统中, 设备在感知信息、计算所需操作并最终作动车辆这一过程中时滞也不可避免. 因此交通流跟驰理论的数学模型本质上应包含时滞. 时滞的存在对各种交通模式的出现及其相互演化产生怎样的影响? 这是值得我们关注的问题. 本文首先综述了各类时间和空间连续的时滞车辆跟驰模型.其次探究这类模型中存在的分岔现象的研究进展, 并指出目前研究中存在的不足. 最后提出作者的一些看法,运用时滞动力系统理论来深入挖掘富含参数的交通流时滞跟驰模型中隐藏的各种的非线性动力学现象, 这样既可以更好解释真实交通中的各种堵塞模式的形成及其演化机制, 又可以结合交通流参数平面内动力学行为从同步观点给出交通堵塞一种分类. 为交通管理部门的交通控制策略制定提供一定的参考依据, 减缓由于司机反应时滞等因素造成的交通堵塞的发生.     

宏观交通流模型的余维2分岔分析

交通流特性是混合交通流建模的一个重要因素. 交通流模型中的分岔现象是导致复杂交通现象的因素之一. 交通流的分岔, 涉及复杂的动力学特征且研究较少. 因此, 提出了一个最优速度模型来研究驾驶员记忆对驾驶行为的影响. 基于带有记忆的最优速度连续交通流模型, 利用非线性动力学, 分析和预测了复杂交通现象. 推导了鞍结 (LP) 分岔存在条件, 并通过数值计算得到了余维1 Hopf (H) 分岔、LP分岔和同宿轨 (HC) 分岔以及余维2广义Hopf (GH) 分岔、尖点 (CP) 分岔和Bogdanov-Takens (BT) 分岔等多种分岔结构. 根据双参数分岔区域的特点, 研究了记忆参数对单参数分岔结构的影响, 分析了不同分岔结构对交通流的影响, 并用相平面描述了平衡点附近轨迹的变化特征. 选择Hopf分岔和鞍结分岔作为密度演化的起点, 描述了均匀流、稳定和不稳定的拥挤流以及走走停停现象. 结果表明, 驾驶员记忆对交通流的稳定性有重要影响; 动力学行为很好地解释了交通拥堵现象; 考虑余维2分岔的影响, 能更好地理解交通拥堵产生的根源, 并为制定有效抑制拥堵的方法提供一定的理论依据.      

非港湾式公交车站站点设置的研究

研究了在同一路段上非港湾式公交车站站点的分散式和集中式设置对道路 交通的影响. 在元胞自动机交通流NaSch模型上, 提出了考虑公交车站站点分散式和集中式 设置的双车道元胞自动机交通流模型, 通过计算机模拟和理论分析, 结果表明: 在开放边界条件下, 分散式公交车站点与集中式公交车站点相比, 影响道路交通通行能力作用显著的减小; 公交车站点之间的间隔、站台的长度、公交车停靠时间以及车流中公交车的比例对交通 流量有显著的影响.     

大城市高架路实测数据分析与交通流模型研究

对上海市中心延安高架路一个路段交通流进行长时间录像拍摄,提取到``车速-车头间距'有效数据26000余对. 应用该批实测数据,对多种常见交通流速密关系模型进行比较研究后发现,一维管流模型在我国高速道路交通流参数计算中具有优势. 提出采用变参数一维管流模型刻画交通流非线性特征的基本方法.      

非港湾式公交车站停靠特性的研究

基于Nagel-Schreckenberg交通流模型(简称NaSch模型),通过引入换道规则,建立包含非港湾式公交车站在内的双车道混合车辆元胞自动机交通流模型.计算机数值模拟表明,在周期边界条件下非港湾式公交车站路段的交通流存在一定的特性,在中等密度区域的拥挤流, 车辆的平均速度与车流密度存在一次幂律关系.      

基于交通流实测数据的加速度研究

采用6 个不同密度下的交通流样本, 从视频中提取大量跟驰车对的车头间距、车速、加速度和速度差数据. 统计分析发现, 加速度值域关于0 点具有对称性; 不同密度下加速度分布具有不同特征; 车头间距、车速和速度差对加速度的影响程度随密度不同而不同. 利用实测数据对GM 模型和Bando 模型进行参数优化, 据此提出一种GM 模型的简化形式和一种改进的Bando 模型, 两者拟合该文实测数据的平均误差都在6% 以下.      

高架路匝道附近的交叉口交通流分析

考虑高架路匝道附近的交叉口交通流问题．所采用的模型是经修正的一维管流交通流模型,在运动方程中引入了弛豫项．基于该模型,对上海市内环线的武宁路匝道附近的交通流进行了案例分析,着重对主干道上的右转车辆干扰效应进行了数值模拟,所得结果与实测数据相当符合．分析表明,右转车辆对主干道的“挤压”效应是引起某些交叉口交通拥塞的重要原因,而设置在繁华路口的高架路匝道加剧了这种拥塞状况。     

三车道宏观交通流模型和扰动演化的数值研究

随着城市交通设施的完善,多车道在城市高速路交通中变得比较普遍. 三车道的出现使车辆变道易于实现,这就增加了交通问题的复杂性. 采用宏观交通流理论,建立了一种允许车辆变道的单向三车道连续交通流模型,以及与之相容的差分离散格式. 数值模拟了初始密度、扰动强度、初始扰动范围等因素对扰动传播和发展演化的影响. 结果显示:扰动波的传播方向和传播速度主要由初始未扰动车流密度大小决定;初始扰动范围的大小对扰动波幅值变化的影响比较大;某一条车道发生的扰动是否会影响其他车道,则受初始车流密度和扰动强度大小两个条件影响;在中等密度多车道交通流中,扰动波的发展过程呈现出复杂的非线性特征,数值格式的选择比单车道更加困难.      

城市道路交通问题与交通流模型

分析了目前城市道路交通存在的严重问题．从连续性描述、统计描述、离散描述3种研究方式,综述了交通流流体力学模型、气体动力论模型、跟驰和元胞自动机模型的研究进展,分析了主要交通流模型的建模思想、动力学方程(或演化规则)以及研究方法,展望了今后交通流模型的发展趋势．     

A new car-following model with consideration of anticipation driving behavior

A new anticipation driving car-following (AD-CF) model is presented based on the effect of traffic anticipation in the real world. The model??s linear stability condition was obtained by applying the linear stability theory. Additionally, a modified Korteweg?Cde Vries (mKdV) equation was derived via nonlinear analysis to describe the propagating behavior of traffic density wave near the critical point. Good agreement between the simulation and the analytical results shows that the stability of traffic flow can be enhanced when the driver??s anticipation effects are considered.     

考虑道路信息和转向灯的可换道BML模型

车辆换道是司机为获得更好行驶条件而采用的常见措施, 而转向灯对车辆换道行为有重要的指导作用. 本文在BML (Biham-Middleton-Levine)模型的基础上加以改进, 提出了综合考虑道路信息和前车转向灯影响的可换道BML模型. 当车辆无法前行时, 如满足换道条件, 则将道路信息(车道密度及平均速度)和转向灯影响量化为车辆换道概率, 确定车辆是否可以换道. 通过数值模拟, 研究了周期边界条件下车辆换道行为对有、无交通灯控制的两种BML模型发生相变的临界密度以及系统通行能力的影响. 模拟结果表明对于无交通灯BML模型, 引入换道规则可以明显提高系统发生相变的临界密度, 在较小尺度下该临界密度接近有交通灯BML模型, 换道效果明显, 并发现了一种新的局部拥堵和自由流的共存相, 讨论了该共存相的生成和演化机制. 在较高密度下局部阻塞将演化为全局拥堵; 对于有交通灯BML模型, 引入换道规则对系统发生相变的临界密度没有明显的影响, 但相变的过渡区域更窄. 这表明有交通灯时, 换道虽然可以改变局部交通特征, 但难以显著影响交通系统的全局特征.      

A car-following model with the anticipation effect of potential lane changing

In this paper, a new car-following model is presented, taking into account the anticipation of potential lane changing by the leading vehicle. The stability condition of the model is obtained by using the linear stability theory. The modified Korteweg-de Vries （KdV） equation is constructed and solved, and three types of traffic flow in the headway-sensitivity space, namely stable, metastable and unstable ones, are classified. Both the analytical and simu- lation results show that anxiety about lane changing does indeed have an influence on driving behavior and that a consideration of lane changing probability in the car-following model could stabilize traffic flows. The quantitative relationship between stability improvement and lane changing probability is also investigated.     

ONE-DIMENSIONAL CELLULAR AUTOMATON MODEL OF TRAFFIC FLOW BASED ON CAR-FOLLOWING IDEA

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A Nonlinear Temporal Headway Model of Traffic Dynamics

In order to describe the dynamics of a group of road vehicles travelling in a single lane, car-following models attempt to mimic the interactions between individual vehicles where the behaviour of each vehicle is dependent upon the motion of the vehicle immediately ahead. In this paper we investigate a modified car-following model which features a new nonlinear term which attempts to adjust the inter-vehicle spacing to a certain desired value. In contrast to our earlier work, a desired time separation between vehicles is used rather than simply being a constant desired distance. In addition, we extend our previous work to include a non-zero driver vehicle reaction time, thus producing a more realistic mathematical model of congested road traffic. Numerical solution of the resulting coupled system of nonlinear delay differential equations is used to analyse the stability of the equilibrium solution to a periodic perturbation. For certain parameter values the post-transient response is a chaotic (non-periodic) oscillations consisting of a broad spectrum of frequency components. Such chaotic motion leads to highly complex dynamical behaviour which is inherently unpredictable. The model is analysed over a range of parameter values and, in each case, the nature of the response is indicated. In the case of a chaotic solution, the degree of chaos is estimated.     

An extended car-following model accounting for the honk effect and numerical tests

In this paper, an extended car-following model is proposed to simulate traffic flow by considering the honk effect. The stability condition of this model is obtained by using the linear stability analysis. The phase diagram shows that the honk effect plays an important role in improving the stabilization of traffic system. The mKdV equation near the critical point is derived to describe the evolution properties of traffic density waves by applying the reductive perturbation method. Furthermore, the numerical simulation is carried out to validate the analytical results and indicates that the traffic jam can be suppressed efficiently via taking into account the honk effect.     

Effect of driver behaviours on the formation and dissipation of traffic flow instabilities

This paper extends a non-local second order continuum traffic model to take into account the timid or aggressive driver behaviours. Based on the proposed model, we derive analytically the effect of timid or aggressive driver behaviours on the instability of traffic dynamics. Simulation results are presented to show how the timid or aggressive driver behaviours influence the formation and dissipation of stop-and-go waves. It is found theoretically and numerically that aggressive drivers tend to stabilize traffic flow whereas timid drivers tend to destabilize traffic flow.     

A new car-following model accounting for varying road condition

In this paper, we develop a new car-following model with consideration of varying road condition based on the empirical data. Firstly, we explore the effects of road condition on uniform flow from analytical and numerical perspectives. The results indicate that road condition has great influences on uniform flow, i.e., good road condition can enhance the velocity and flow and their increments will increase when road condition becomes better; bad road conditions will reduce the velocity and flow and their reductions will increase when road condition turns worse. Secondly, we study the effects of road conditions on the starting and braking processes. The numerical results show that good road condition will speed up the two processes and that bad road condition will slow down the two processes. Finally, we study the effects of road condition on small perturbation. The numerical results indicate that the stop-and-go phenomena resulted by small perturbation will become more serious when the road condition becomes better.     

基于元胞自动机模型的C型交织区交通流特性

根据C型双侧交织区的车辆换道特征建立相应的换道规则,采用多车道元胞自动机模型研究交织区系统的交通流特性. 通过数值模拟得到了不同交织区长度下的相图,表明当主路和匝道交通流均为自由流时,交织区长度对系统影响不大,但当主路或匝道拥挤时,交织区长度的增加可以明显改善入口匝道的交通流状况. 进一步讨论了主路畅通而交织流量较大情形下主路上的车辆密度、速度和换道频率分布,发现换道集中在合流区和分流区附近,并造成相应路段上的局部拥堵.      

Feedback control for the lattice hydrodynamics model with drivers’ reaction time

In this paper, a new lattice hydrodynamic model (LH model) of traffic flow under consideration of reaction time of drivers and a corresponding feedback control scheme are proposed. Based on the model, stability analysis is conducted through linear stability analysis of transfer function. The obtained phase diagram indicates that the reaction time of driver can affect the instability region of traffic flow. Under the action of a feedback control, the unstable region is shrunken to reach suppressing jams. The numerical simulations are performed to validate the effect of reaction time of driver in the new LH model. The study results confirm that the reaction time of driver significantly affects the unstability of traffic system, and the feedback control can suppress traffic jams. Furthermore, it is found that the traffic system from the chaotic traffic state to periodic steady one is successfully realizing the control of traffic system.