基于车载电子标签的交通拥堵状态判别设计

提出一种基于车载电子标签的交通状态判别方法;该判别方法通过在路段安装背靠背式接收机避免反向车道车辆干扰,采用有源主动电子标签扩大读写范围与精度,利用扫描区间内获得的电子标签数量、更新比率、停留时间等信息,配合交叉口信号灯状态,构建控制系统与车载电子标签的联动体系,进行交通状态,尤其是拥堵状态的判别;经VISSIM交通仿真软件的二次开发,模拟车载电子标签环境,仿真试验验证该方法可有效判别交通状态,判别的平均准确度在85%以上。     

基于RFID车载电子标签的公交优先控制策略研究

针对现有的信号控制系统不能对达到交通流做出精准预测,只能被动适应交通流达到而无法主动引导交通流。提出基于RFID车载电子标签车路通信环境,引导公交车辆适时到达并通过交叉口。以交叉口总延误最小化为目标,综合考虑当前交通流运行状态,建立公交信号优先控制模型,最大限度降低交叉口的车均延误,减少平均停车次数,使绿灯的利用率最大化。仿真实验表明,控制模型的控制效益明显提高,实现公交优先目标。     

基于能力区域的交通状态预测方法

交通状态预测是交通流诱导和交通信息发布系统的重要依据.本文提出了一种基于能力区域的城市快速路交通状态预测方法,该方法通过构建神经网络分类器的能力区域,根据样本数据与交通状态类簇之间的空间距离,预测道路交通状态等级.神经网络分类器的能力区域能够有效融合时间、空间等多种特征,并且不需要考虑各特征之间的相关性,具有很强的适应性.实验结果表明,与经典的预测方法相比,其预测误差明显降低,均等系数增大,基于能力区域的方法预测交通状态具有较高的准确性.     

基于Wi-Fi Direct的道路交通状态信息采集方法

针对传统交通状态信息采集中采用的环形线圈车辆检测器存在布设和维护难度较大等问题,提出了一种基于Wi-Fi Direct的道路交通状态信息采集方法,以实现对基本的道路交通流状态参数进行采集估计。该方法利用车-路通讯设备实现车辆与路侧设备的通信;以车载通讯设备的Wi-Fi芯片介质访问控制层地址完成车辆个体识别;通过车载通讯设备中的北斗定位装置向路侧设备提供车辆实时位置及时间信息,进而实现道路区段内交通流基本状态信息估计。实验测试表明,该方法能够完成路段平均速度、交通流量及车流密度的采集和估计,是一种有效的道路交通信息采集方法。     

基于RFID电子标签的公交信号单点优先策略

为加强路口单元与公交车辆的信息交互,提高公交信号优先系统的效能,以RFID电子标签为信息交互中介,建立车路通信环境,构建交通信号系统、公交系统为一体的公交信号优先系统;通过与电子标签的信息交互,路口单元对公交车的信号优先请求进行分级错开,计算信号配时、建议车速、驻站时间等控制参数,制定出基于引导的优先方案,在交叉口实现公交车的优先通行与安全行驶服务;实验结果表明,在高饱和状态下,文章引导策略能使交叉口公交的平均延误降低30%,在中、低饱和状态下的效益更佳。     

应用于高速轮轨交通的高温超导同步直线电机研究

为实现高速铁路列车突破600km/h的速度极限,本文提出了一种与现有轮轨交通兼容的高温超导同步直线电机方案,并通过有限元方法建立了高温超导同步直线电机的仿真模型.设计并制作了小型实验样机,其定子由三相铜绕组与硅钢材质的铁轭构成,使用二代高温超导材料YBCO带材绕制车载磁体.通过实验方法验证了模型的有效性,并用该模型研究了高温超导线圈回路电流、线圈匝数和气隙对电机推进力和法向力等电磁力特性的影响规律.本文的研究结果为高温超导同步直线电机在轮轨交通领域中的应用提供了可行性依据.     

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     

基于改进蚁群算法的交通最优路径方法研究

本文提出一种基于改进蚁群算法的交通路径最优方法,首先根据图论的思想构建了城市交通网络模型,结合层次分析法考虑了道路长度、交叉口停滞、交通拥挤、道路容量、天气状况等五个主要因素。然后在MATLAB平台下,采用改进的蚁群算法对静态交通网络和动态交通网络分别进行最短路径的求解,最后进行了对比分析。研究结果表明,在综合考虑以上五种因素的情况下,动态交通网络下的路径最优算法能为出行者找到更准确更便捷的路线。     

交叉口混合交通流元胞自动机模型及仿真研究

本文以右转机动车和直行自行车为对象研究交叉口混合交通流特性.基于交叉口机非干扰特性,将机动车元胞模型和自行车元胞模型进行了耦合,建立了考虑自行车穿越机动车延时、机动车穿越自行车间隙和冲突区占据处置等规则的交叉口混合交通流元胞自动机模型(NS-BCA).对右转机动车与直行自行车混合交通流进行了仿真,从流量-车辆到达率关系、交通流相位相变、交通流相位-到达率-混合交通流状态等方面研究了交叉口混合交通流的机非干扰机理.     

道路交通流状态的多参数融合预测方法

针对道路交通流普遍存在的混沌特性以及单交通参数不足 以全面反映交通流状态的实际情况,考虑交通动力学系统中多个 交通参数之间的关联关系,提出一种新的多参数混沌时间序列预 测算法.该算法在相空间重构理论的基础上,借助Bayes估计将多个参数在 同一高维相空间中进行相点最优融合,从而增加重构相空间的系统信息量, 使得相空间的相点轨迹更加逼近原交通系统的动力学行为.同时借鉴单 参数混沌时间序列预测方法,从不同角度对动力学系统的运动状态进行描 述,以实现多参数时间序列的混沌预测.实验结果表明,通过融合多交通参数时 间序列,获得了更加完整的交通流状态变化特征.与单交通参数时间序列的预测 结果相比,其预测误差显著降低,均衡系数相应增大,提高了交通流状态预测的准确率.     

A cellular automata model for urban traffic with multiple roundabouts

Urban transportation with multiple roundabouts is facing significant challenges such as traffic congestion, gridlock and traffic accidents. In order to understand these behaviors, we propose a two-dimensional cellular automata (CA) model, where all streets are two-way, with one lane in each direction. To allow the turning movement, a roundabout is designed for each intersection where four roads meet. The distance between each pair of roundabouts is configured with the parameter K while the turning behavior of drivers is modeled by a parameter γ. To study the impact of these different parameters on the urban traffic, several traffic metrics are considered such as traffic flow, average velocity, accident probability and waiting time at the entrance of roundabout. Our simulation results show that the urban traffic is in free flow state when the vehicle’s density is low enough. However, when the density exceeds a critical density ρ_c, the urban traffic will be in gridlock state whenever γ is nonzero. In the case where $\gamma =0,$ the urban traffic presents a phase transition between free flow and congested state. Furthermore, detailed analysis of the traffic metrics shows that the model parameters (γ, K) have a significant effects on urban traffic dynamics.     

Techniques for the investigation of road traffic noise in regions of restricted flow by the use of digital computer simulation methods

Computer methods of calculating and predicting the noise from road traffic operating in restricted flow conditions are discussed. A method of calculating the noise from road traffic as a function of the manoeuvring parameters by means of a Monte Carlo digital computer simulation model is briefly described. The model is used in deriving correction contours for single streams of traffic which enable free flow L₁₀ levels to be modified to allow for a flow restriction. Flow restrictions of the type encountered at traffic signals, priority intersections and pelican crossings are considered. The contours cover a stretch of road 600 m long and a distance of 60 m from the kerb line and in general show a reduction in L₁₀ level in transferring from the free to the restricted flow situation. A method of applying the contours as a modification of the United Kingdom Department of the Environment prediction method for L₁₀ is proposed and compared with experimental results. Computer simulation models of complete road intersections are discussed. Two types of intersection controls are considered, the traffic signal control and the roundabout. The results of the two types of simulation are compared and the L₁₀ level adjacent to the accelerating traffic streams is generally found to be greater than that adjacent to decelerating streams. Experimental results for both types of intersection are compared with simulation runs in which the observed traffic parameters are used.     

Dynamics of traffic flows on crossing roads induced by real-time information

Traffic flows on crossing roads with an information board installed at the intersection have been simulated by a cellular automaton model. In the model, drivers have to enter the road with a shorter trip-time indicated on the information board, by making a turn at the intersection if necessary. The movement of drivers induces various traffic states, which are classified into six phases as a function of the car density. The dynamics of the traffic is expressed as the return map in the density–flow space, and analyzed on the basis of the car configuration on the roads.     

A new lattice model of traffic flow with the consideration of the traffic interruption probability

In this paper, we present a new lattice model which involves the effects of traffic interruption probability to describe the traffic flow on single lane freeways. The stability condition of the new model is obtained by the linear stability analysis and the modified Korteweg-de Vries (KdV) equation is derived through nonlinear analysis. Thus, the space will be divided into three regions: stable, metastable and unstable. The simulation results also show that the traffic interruption probability could stabilize traffic flow.     

A new lattice hydrodynamic model accounting for the traffic interruption probability on a gradient highway

In this paper, a novel lattice hydrodynamic model is presented by accounting for the traffic interruption probability on a gradient highway. The stability condition can be obtained by the use of linear analysis. Linear analysis demonstrates that the traffic interruption probability and the slope will affect the stability region. Through nonlinear analysis, the mKdV equation is derived to describe the phase transition of traffic flow. Furthermore, the numerical simulation is carried out, and the results are consistent with the analytical results. Numerical results demonstrate that the traffic flow can be efficiently improved by accounting for the traffic interruption probability on a gradient highway.     

Nonlinear analysis of an improved continuum model considering mean-field velocity difference

Based on the velocity gradient model, an extended continuum model with consideration of the mean-field velocity difference is proposed in this paper. By using the linear stability theory, the linear stability criterion of the new model is gained, which proved that mean-field velocity difference has significant influence on stability of traffic flow. The KdV–Burgers equation is derived by using non-linear analysis method and the evolution of density wave near the neutral stability line is explored. Numerical simulations are carried out how mean-field velocity difference affect the stability of traffic flow, and energy consumption is also studied for this new macro model. At the same time, complicated traffic phenomena such as local cluster effects, shock waves and rarefaction waves can be reproduced in the new model by numerical simulation. Numerical results are consistent with the theoretical analysis, which indicates that the mean-field velocity difference not only suppresses traffic jam, but also depresses energy consumption.     

Phase diagram of a traffic roundabout

We propose a simple cellular automaton model to study the traffic dynamics in a roundabout. Both numerical and analytical results are presented. We are able to obtain exact solutions in the full parameter space. Exact phase diagrams are derived. When the traffic from two directions mixed, there are only five distinct phases. Some of the combinations from naive intuition are strictly forbidden. We also compare the results to a signaled intersection.     

Multiclass first-order simulation model to explain non-linear traffic phenomena

With the first-order traffic model of Lighthill, Whitham and Richard (LWR), many simple traffic problems can be represented analytically such as a shock formation. However, the LWR model has some deficiencies. For example, among the other things, it fails to replicate interesting non-linear phenomena such as hysteresis and capacity drop as well as the dispersion of traffic platoon when there exists a distribution of desired speeds in heterogeneous traffic. To this end, in this paper, we propose a novel multiclass first-order simulation model based on an approximation of Riemann solver. In the developed model, each vehicle class is only characterized by their desired speeds in a free-flow traffic state where overtaking is allowed. However, when traffic is congested, all vehicle classes must travel at the same congested speed and overtaking is not possible. Numerical results show that the proposed model is not only more accurate and reliable than the existing models but also able to explain non-linear traffic phenomena on freeways.     

Freezing transition in a four-directional traffic model for facing and crossing pedestrian flow

We study the traffic behavior in the facing and crossing traffic of pedestrians numerically and analytically. There are four kinds of walkers, those moving to east, to west, to north, and to south. We present the mean-field approximation (MFA) model for the four-directional traffic. The model is described in terms of four nonlinear difference equations. The excluded-volume effect and directionality are taken into account. The fundamental diagrams (current-density diagrams) are derived. When pedestrian density is higher than a critical value, the dynamical phase transition occurs from the free flow to the frozen (stopping) state. The critical density is derived by using the linear stability analysis. The velocity and current (flow) at the steady state are derived analytically. The analytical result is consistent with that obtained by the numerical simulation.     

A new lattice model of traffic flow with the consideration of the driver?s forecast effects

In this Letter, a new lattice model is presented with the consideration of the driver?s forecast effects (DFE). The linear stability condition of the extended model is obtained by using the linear stability theory. The analytical results show that the new model can improve the stability of traffic flow by considering DFE. The modified KdV equation near the critical point is derived to describe the traffic jam by nonlinear analysis. Numerical simulation also shows that the new model can improve the stability of traffic flow by adjusting the driver?s forecast intensity parameter, which is consistent with the theoretical analysis.