城市交通多线路协调优化仿真模型研究

为缓解城市交通拥堵,提高道路利用率,提出一种新的简单实用的城市交通多线路协调优化控制模型及时空相位演化方法,并给出了改进的遗传优化算法。通过仿真系统的开发,实现了城市交通的多线路优化控制仿真并获得了满意的效果。对比优化前后的数据,优化后调度线路上的车流以最少平均停车次数和最短平均延迟时间到达目的地。利用本优化模型可以实现以较小的代价成本疏导城市交通,提高城市道路通行能力。     

Designing large‐scale interactive traffic animations for urban modeling

Designing and optimizing traffic behavior and animation is a challenging problem of interest to virtual environment content generation and to urban planning and design. While some traffic simulation methods have appeared in computer graphics, most related systems focus on the design of buildings, roads, or cities but without explicitly considering urban traffic. To our knowledge, our work provides the first interactive approach which enables a designer to specify a desired vehicular traffic behavior (e.g., road occupancy, travel time, emissions, etc.) and the system will automatically compute what realistic 3D urban model (e.g., an interconnected network of roads, parcels, and buildings) yields the specified behavior. Our system both altered and improved traffic behavior in novel procedurally‐generated cities and in road networks of existing cities. Our urban models contain up to 360 km of roads, 300,000 vehicles, and typically cover four hours of simulated peak traffic time. The typical editing session time to “paint” a new traffic pattern and to compute the new/changed urban model is two to five minutes.     

封闭型小区交通开放对城市交通的影响

随着交通需求的增加,城市交通问题日益严重,能否通过开放现有封闭型小区的道路以缓解城市交通拥堵是一个值得研究的问题.本文针对这一问题,建立了基于最短路的交通分流线性规划网络模型,提出了交通量改善因子、路段饱和度均值以及路段饱和度标准差等三个评价指标,以评价和对比封闭性小区开放前后的交通量与道路占用程度,从而反映了封闭性小区的开放对城市交通的具体影响.本文对两种不同的交通网络及交通流量数据进行了仿真与模型求解,结果表明：尽管小区开放后路网密度提高,有可能使得总交通负荷降低,但并非任何小区开放均能缓解城市交通拥堵.小区面积、位置、外部及内部道路状况等诸多因素都能影响路网的交通状态,所以,是否开放封闭型小区,需要用针对具体的小区与周边道路状况进行评估后再进行决策.     

城市交通过饱和状态下干线信号的多目标仿真优化研究

针对城市交通过饱和状态下的干线信号优化问题,分析了交通控制目标对车辆排队的影响,提出以绿信比、相序、相位差和周期为优化参数,以车辆平均时延、系统平均排队-车道长度比和系统通行能力为优化目标的交通信号仿真优化模型。构建了优化模型的实施框架,该框架采用自主构建的微观交通仿真环境来获取信号方案评价指标,改进多目标优化算法NSGAII中的重复个体问题,完成对干线各交叉口信号配时方案的同时优化。最后,利用采集的交通数据对由3个交叉口组成的干线进行实例验证,验证结果表明,在过饱和状态下,所提出的信号优化方法不仅可以有效控制车辆排队长度,均衡车辆分布,同时在系统通行能力、车均时延方面表现更佳。     

交通网络车流量的分布式协同优化方法研究

针对城市交通网络主干道车流量密度非连续特性,分析了交通网络车流量分段仿射模型.从最小化车流量延迟角度,给出了优化目标函数并进行凸分析.在此基础上,将城市交通网络系统描述为非完整性约束条件的非线性动态系统,利用反步法通过控制变量代换和状态转换将该系统转化为时变可控协同标准型的一般形式,并设计城市交通网络系统的分布式协同控制律.然后在城市主干道交通网络模型中,分别对协同分布式优化方法、定时控制、感应控制三种交通控制算法进行对比仿真分析,从仿真结果可以看出,本文所提出的协同分布式优化方法具有较好的性能,有效的降低了交通网络中车辆平均等待时间.     

基于蚁群算法的城市快速路优化控制

根据城市快速路交通流的特性,以宏观稳态交通流Macro模型为基础,将快速路虚拟划分为多个路段,将车辆在快速路系统内总的服务流量最大及入口匝道车辆平均等待时间最小作为优化控制目标,设计快速路多匝道联合控制模型,并采用蚁群优化算法对设计的控制模型进行求解计算,以确定各匝道最优调节率。模拟实验结果表明,通过多匝道联合控制,能够提高城市快速路系统的运行效率,减少交通事故及交通拥堵的发生概率。     

城市交通网络宏观控制模型及仿真实现

为研究适合城市交通网络控制系统应用的交通流预测模型,在改进Van Den Berg, M的路段交通流模型的基础上,建立了以路口交通流为基本建模单元,以动态非线性离散方程反映交通流变化的城市交通网络宏观模型.为验证该模型能有效地预测城市路网的交通流信息,在VC++net环境下,开发了城市交通宏观控制模型仿真系统UTFS,设计了网络拓扑结构模块,以适应不同规模、不同复杂程度的实际交通网络的仿真要求.最后选取典型网络进行应用研究.仿真结果表明:该模型满足交通控制对控制模型的实时性和精度要求,该仿真系统可以作为城市交通网络宏观控制模型验证的有效工具,也可以作为城市交通控制系统控制和优化研究的辅助工具.     

Design of Sustainable Cordon Toll Pricing Schemes in a Monocentric City

This paper addresses the design issue of sustainable cordon toll pricing schemes in a monocentric city. An analytical model that maximizes the total social welfare of urban system is first proposed for simultaneous optimization of the cordon toll location and charge level. The solution properties of the model with/without considering traffic congestion and/or environmental effects are explored and compared analytically. The proposed model is then extended to explicitly incorporate the effects of subsidizing the retrofit of old vehicles on reduction in average vehicle emissions. The optimal subsidy scheme for maximizing the social welfare of the system is also determined. Finally, a numerical example is given to illustrate the model applications. Insightful findings are reported on the interrelationships among cordon toll scheme, traffic congestion and environmental effects, urban population distribution, and subsidy scheme as well as their implications in practice.     

城市交通多线路协调控制优化仿真系统设计

为了实现城市交通优化控制,提高城市道路通行能力,本文首先提出了城市交通多线路协调控制优化仿真模型,并在此模型基础上给出了时空相位演化算法和改进的遗传优化算法(GA),然后总结了城市交通多线路协调控制优化仿真系统的基本结构、数据结构和技术路线,并完成了城市交通多线路协调控制优化仿真系统设计与开发。该仿真系统结构简单,建模方便,可以适用于任何城市交通优化控制,解决了城市交通多线路协调控制(多线路绿波带)难题。通过对佛山市某路网的实际建模与仿真,该系统取得了较好的交通优化效果。     

Urban traffic congestion propagation and bottleneck identification

Bottlenecks in urban traffic network are sticking points in restricting network collectivity traffic efficiency. To identify network bottlenecks effectively is a foundational work for improving network traffic condition and preventing traffic congestion. In this paper, a congestion propagation model of urban network traffic is proposed based on the cell transmission model （CTM）. The proposed model includes a link model, which describes flow propagation on links, and a node model, which represents link-to-link flow propagation. A new method of estimating average journey velocity （AJV） of both link and network is developed to identify network congestion bottlenecks. A numerical example is studied in Sioux Falls urban traffic network. The proposed model is employed in simulating network traffic propagation and congestion bottleneck identification under different traffic demands. The simulation results show that continual increase of traffic demand is an immediate factor in network congestion bottleneck emergence and increase as well as reducing network collectivity capability. Whether a particular link will become a bottleneck is mainly determined by its position in network, its traffic flow （attributed to different OD pairs） component, and network traffic demand.     

Design of Regulatory Traffic Light Control Systems with Synchronized Timed Petri Nets

Fixing the phases is one of the common methods to control an urban traffic network. Once a road is filled with a high traffic flow approaching its capacity, the conventional traffic light controller is not able to handle this traffic congestion phenomenon well. In this paper, we propose a novel regulatory traffic light control system to handle such traffic congestion by using synchronized timed Petri nets (STPNs). Three kinds of intersections in an urban traffic network are defined and employed to demonstrate our new regulatory traffic light control system models. Finally, the liveness and reversibility of the proposed STPN models are proven through the reachability graph analysis method. To our knowledge, this is the first work that solves a traffic congestion problem with a regulatory traffic light control technique that is effective in preventing vehicles from entering traffic congestion zones.     

基于agen t 的城市交通信号控制

利用agent技术对城市交通信号控制进行研究．首先给出了区域agent(ARA)的组成和结构，然后给出了城市交通控制的模型和协调算法．基于agent技术的城市交通控制系统能对交通状况进行实时反映和处理．在此模型基础上，应用博弈论的相关知识给出城市交通信号协调控制算法．最后通过仿真程序验证了该模型和算法的有效性和实用性．     

面向优先车辆感知的交通灯优化控制方法

智慧交通灯控制能够有效地改善道路交通的秩序和效率.在城市交通网络中,具有紧急任务的特殊车辆对于通行效率的要求更高.目前已有的智慧交通灯控制算法通常对路网中的所有车辆一视同仁,没有考虑到特殊车辆的优先性,而传统的控制特殊车辆优先通行的方法基本上都是采用信号抢占的方式,对普通车辆的通行干扰过大.为此,本文提出了一种面向优先车辆感知的交通灯优化控制方法,通过与道路环境的不断交互来学习交通灯控制策略,在设置状态和奖励函数时增加特殊车辆的权重,并利用Double DQN和Dueling DQN来提升模型表现,最终在城市交通模拟器SUMO中进行仿真实验.在训练趋于稳定之后,与固定时长控制方法的对比实验结果显示,本文方法能够将特殊车辆与普通车辆的平均等待时间分别缩短68%与22%左右,与不考虑优先级的方法相比,特殊车辆的平均等待时间也有35%左右的优化,验证了本文方法能够在提高车辆的通行效率的同时体现出对特殊车辆的优先处理.同时实验也表明本文方法能够扩展应用于多路口场景中.     

基于CPN的城市智能交通信号控制系统建模

提出了一种城市交通控制系统的分布式结构及控制策略，介绍了CPN(Colorcd Petrj Nets)的基本概念及建模特性，着重探讨了借助CPN建模技术对城市智能交通信号控制系统进行的建模分析。     

Detailed traffic animation for urban road networks

We present a new agent-based system for detailed traffic animation on urban arterial networks with diverse junctions like signalized crossing, merging and weaving areas. To control the motion of traffic for visualization and animation purposes, we utilize the popular follow-the-leader method to simulate various vehicle types and intelligent driving styles. We also introduce a continuous lane-changing model to imitate the vehicle’s decision-making process and dynamic interactions with neighboring vehicles. By applying our approach in several typical urban traffic scenarios, we demonstrate that our system can well visualize vehicles’ behaviors in a realistic manner on complex road networks and generate immersive traffic flow animations with smooth accelerating strategies and flexible lane changes.     

Dijkstra算法在城市道路网络中的应用

本文介绍了一个利用自然语言处理技术进行城市交通查询的系统.在研究城市道路网络特征基础上,建立城市道路网络模型及其数据库,应用Dijkstra算法对城市道进行最短路径查询,该算法是从起点和终点分别用二叉树按起点到终点和终点到起点的方向进行搜索,并得到良好的查询结果.     

基于Petri网的交通控制系统建模与评估

基于Petri网理论,提出一种对十字路口交通控制系统建模和性能评估的方法.该方法根据路口间的交通流量,计算在不同红绿灯相位差的情况下,各个路口的平均等待队列长度和平均等待时间,从而得出最优的红绿灯相位差.与通常的Petri网模型相比,该模型减少了分析的复杂性,提高了城市路网的通行能力.     

Real-time traffic incident detection using a probabilistic topic model

Traffic congestion occurs frequently in urban settings, and is not always caused by traffic incidents. In this paper, we propose a simple method for detecting traffic incidents from probe-car data by identifying unusual events that distinguish incidents from spontaneous congestion. First, we introduce a traffic state model based on a probabilistic topic model to describe the traffic states for a variety of roads. Formulas for estimating the model parameters are derived, so that the model of usual traffic can be learned using an expectation–maximization algorithm. Next, we propose several divergence functions to evaluate differences between the current and usual traffic states and streaming algorithms that detect high-divergence segments in real time. We conducted an experiment with data collected for the entire Shuto Expressway system in Tokyo during 2010 and 2011. The results showed that our method discriminates successfully between anomalous car trajectories and the more usual, slowly moving traffic patterns.     

A macroscopic model with the advantages of microscopic model: A review of Cell Transmission Model’s extensions for urban traffic networks

This paper reports a review of the extensions and application of the Cell Transmission Model (CTM). Those extensions are models able to simulate complex urban traffic dynamics with all the advantages of macroscopic and microscopic urban traffic model. Over the past few years researchers have been trying to increase the level of detail by extending CTM and introducing new formulations to improve the application of the model in urban traffic. The authors classified the papers while taking into consideration all those factors characterizing the urban traffic, arterial and intersection traffic flow in particular. One of the primary goals of transport research is to develop a general framework of urban traffic networks that might be applied from a realistic point of view. Recent studies about traffic simulations have shown that, among various macroscopic simulation models, the CTM has the potential to achieve this objective. We have also reported our model the CTM_UT that improves the CTM for Urban Traffic. We believe that it is possible to apply this model to ITS application, hence increase the accuracy of the macroscopic model while maintaining the computational advantages and provide an accurate prediction of travel time approach.     

基于层级控制的宏观基本图交通信号控制模型

针对城市交通子区内部与边界交叉口的协调控制问题,提出基于分层多粒度与宏观基本图的交通信号控制模型HDMF.首先利用城市交通系统的分层多粒度特性与粗糙集理论描述交通要素的实时状态;然后结合基于背压算法的分布式交叉信号控制和交通元素的动态特性,计算交叉口相位压力并对相位进行决策;最后使用宏观基本图(MFD)实现区域驶出总流...