Adaptive signal control and coordination for urban traffic control in a connected vehicle environment: A review

Existing signal control systems for urban traffic are usually based on traffic flow data from fixed location detectors.Because of rapid advances in emerging vehicular communication,connected vehicle(CV)-based signal control demonstrates significant improvements over existing conventional signal control systems.Though various CV-based signal control systems have been investigated in the past decades,these approaches still have many issues and drawbacks to overcome.We summarize typical components and structures of these existing CV-based urban traffic signal control systems and digest several important issues from the summarized vital concepts.Last,future research directions are discussed with some suggestions.We hope this survey can facilitate the connected and automated vehicle and transportation research community to efficiently approach next-generation urban traffic signal control methods and systems.

Medieval Towns, Traffic and Urban Planning Half a Century since the First Pedestrian Zone in Siena, Italy

The Italian town is known as a collection of wails, gates, towers, palaces and cathedrals. The lanes and the squares were created in the Middle Ages, with an urban fabric suitable for horses and carriages, not for motor cars. At the beginning of the 1960s, it was no longer possible to delay a solution to the problem of traffic and the first ＂pedestrian isle＂ was realized in the centre of Siena in 1965. Other towns in a few years followed this virtuous example. Acts against traffic avoided the building of urban motorways and the demolition of ancient buildings that would have given the ＂coup de grace＂ to several important historic centres.

A Dynamic Road Incident Information Delivery Strategy to Reduce Urban Traffic Congestion

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.

A Framework for Intelligent Decision Support System for Traffic Congestion Management System

Traffic congestion problem is one of the major problems that face many transportation decision makers for urban areas. The problem has many impacts on social, economical and development aspects of urban areas. Hence the solution to this problem is not straight forward. It requires a lot of effort, expertise, time and cost that sometime are not available. Most of the existing transportation planning software, specially the most advanced ones, requires personnel with lots practical transportation planning experience and with high level of education and training. In this paper we propose a comprehensive framework for an Intelligent Decision Support System (IDSS) for Traffic Congestion Management System that utilizes a state of the art transportation network equilibrium modeling and providing an easy to use GIS-based interaction environment. The developed IDSS reduces the dependability on the expertise and level of education of the transportation planners, transportation engineers, or any transportation decision makers.

Practical Strategies for Urban Rail Transit Loop Planning, Construction, and Operation

Urban rail transit loops are essential in urban rail transit systems and transportation networks.However,precise requirements and reference standards for rail transit loop design have yet to be established.There are certain areas for improvement in planning,construction,and operation.In the planning and design of urban rail transit loops,the scale of the city and the relationship between line operations should be considered to ensure that the line conforms to the city’s operating traffic conditions and can effectively cater to peak passenger flow requirements.This article presents strategies for planning,constructing,and operating urban rail transit loops,laying the foundation for the healthy operation of urban rail transit.

An urban traffic environment model

Urban environment pattern depends heavily upon urban traffic pattern, the balance between traffic (implicit production) and environment leads to the urban sustainable development. An integrated urban traffic environment model consists of three components of urban production variables (population density, GDP, salary, etc. in blocks), urban traffic variables and urban environmental variables; and two links between urban traffic planning variables and urban environment variables, and between spatial interaction model (SIM) and traffic planning variables as well. The model is quite useful in urban environment impact assessment; urban traffic management; urban sustainable development planning; and urban development decision\|making.

KSUTraffic: A Microscopic Traffic Simulator for Traffic Planning in Smart Cities

Simulation is a powerful tool for improving,evaluating and analyzing the performance of new and existing systems.Traffic simulators provide tools for studying transportation systems in smart cities as they describe the evolution of traffic to the highest level of detail.There are many types of traffic simulators that allow simulating traffic in modern cities.The most popular traffic simulation approach is the microscopic traffic simulation because of its ability to model traffic in a realistic manner.In many cities of Saudi Arabia,traffic management represents a major challenge as a result of expansion in traffic demands and increasing number of incidents.Unfortunately,employing simulation to provide effective traffic management for local scenarios in Saudi Arabia is limited to a number of commercial products in both public and private sectors.Commercial simulators are usually expensive,closed source and inflexible as they allow limited functionalities.In this project,we developed a local traffic simulator“KSUtraffic”for traffic modeling,planning and analysis with respect to different traffic control strategies and considerations.We modeled information specified by GIS and real traffic data.Furthermore,we designed experiments that manipulate simulation parameters and the underlying area.KSUTraffic visualizes traffic and provides statistical results on the simulated traffic which would help to improve traffic management and efficiency.

Calibration of a Microscopic Model of an Urban Traffic Network

Traffic simulation models have the potential to provide an objective, cost-effective and flexible approach to assessing system design, traffic operations and management strategies. In that regard, the calibration and validation of simulation model is crucial for appropriate decision making process. This paper presents an application of microscopic simulation model calibration and validation procedure for a multimodal urban traffic network. Model is developed by VISSIM and VISSIG software tools.

Research on Planning & Evaluation for Track Traffic Under China's Sustainable Development Strategy

The author advances some basic problems of planning & evaluating for track traffic in the process of putting sustainable development strategy in practice and stresses the study of planning and evaluating method system for track traffic and environment strategy. Summaries and main creative points presented in the thesis are as follows: ①The changes of track traffic planning objects caused by the concept of sustainable development are analyzed; ②The theory & method of track traffic planning optimal decision is set up ; ③Environment impact assessment for track traffic planning is advanced; ⑤ Urban mass transit network planning is studied; ④Planning of intercity rail system——the alignment optimization of dedicated passenger line and high speed railway line is studied ; ⑥ An overall evaluation index system for sustainable development of track traffic planning is established; ⑦ The track traffic building capacity for sustainable development is studied. Further more, the effect of the method and models with empirical studies is verified. The corresponding application software is realized to provide information service and decision making support to track traffic planning for putting theory into practice.

Traffic Calming in Quebec： Speed Humps and Speed Cushions

Speed management is an essential tool in ensuring the improved safety of users of urban roads, particularly vulnerable users. It relies on several measures： awareness campaigns, speed control, as well as the development and operation of the road infrastructure. Municipalities in Quebec are increasingly resorting to the development of traffic calming measures, and are facing numerous questions concerning their installation and their effectiveness. To respond to this need, the ministere des Transports du Quebec （Quebec Department of Transport） has begun publishing a series of fact sheets on a variety of traffic calming measures, including speed humps and speed cushions, raised crosswalks and intersections, neckdowns, centre islands and chicanes. A general fact sheet introduces all of the measures and notably outlines the procedure for pre-implementation analysis. Each fact sheet dedicated to an individual measure outlines the implementation context, advantages and disadvantages, geometric characteristics, effectiveness at reducing speed, and maintenance requirements, including winter maintenance. Two fact sheets are already published： the general fact sheet and the fact sheet on speed humps and speed cushions. The fact sheets as well as examples of measures implemented in municipalities are available on the minist6re＇s web site under Partenaires-Municipalites-Securite routiere.

Study on the Layout of Urban Planning in Rapid Urbanization Areas under the Background of Air Pollution

China＇s urbanization has been over the medium-term process,which has made great achievements,but also triggered a huge problem of air pollution. Air pollution has become a big problem after the water pollution in China,and a serious threat to people＇s life and health. Under the background of ＂ the construction of beautiful China＂ and rapid urbanization,how to build a beautiful home has become the focus of attention. Taking Shenyang as an example,the author contrastively analyses the spatial distribution of the main air pollutants（ PM10,PM2. 5,and SO2） and the present situation of land use,and thus finds out the rules between pollutants distribution and land use. Then combining the urban planning scheme and the rules obtained above,reasonable suggestions are proposed for the scheme to improve the air quality,and reduce or avoid air pollution,and providing the basis for the construction of a piece of blue sky. The conclusions are as follows： 1 air pollutants concentration above Light Oil Gas Making Factory in south vice city of Shenyang reaches the peak value,and industrial point source is the main air pollutants emission source; 2 pollutants concentration above greenbelt is the lowest; 3 the overall spatial structure of urban planning can insulate the industrial agglomeration areas to some extent; greenbelt planning covers 40%- 50% of the area with high concentration of air pollutants,and it is suggested to achieve full coverage; traffic planning can achieve shunt most of the pollutants in many regions,but it can also expand the scope of pollutants in some certain regions,in such regions,it should reduce the road density.

Research on Urban Transportation Planning Strategies in China Under the“New Normal”

In order to explore the development direction and strategy of China’s urban transportation planning,drive the development of urban transportation and urban economic progress,as well as respond to the changing trends and challenges of the market under the“new normal,”this paper first analyzes the current situation of China’s transportation industry under the“new normal,”investigates the relationship between transportation and urban planning,and then proposes strategies for China’s urban transportation development and planning as reference.

基于复杂网络的高速公路交通事故风险动态演化模型

为有效挖掘高速公路交通事故规律信息,基于复杂网络理论提出高速公路交通事故致因网络构建方法.从风险结构与风险模式两方面定义风险传播机制,通过高速公路交通事故致因网络与风险传播机制的有机结合,建立了高速公路交通事故风险演化模型.以高速公路重特大交通事故为例,对201份高速公路重特大交通事故调查报告进行风险分析.结果表明,基于复杂网络的风险演化模型适用于高速公路的交通事故风险分析;通过高速公路交通事故风险演化模型可对各致因的风险传播特性进行解析与归类,从而制定出针对不同情形致因的控制策略,为高速公路交通事故风险演化研究提供新思路.

面向流域治理与城镇发展统筹的城市水系统规划协同机制探讨 ——广东东莞生态园实证研究

统筹流域治理与城镇发展是系统解决当前城市发展过程中遇到的水资源短缺、水生态破坏、洪涝灾害频发的关键路径。本文在辨析流域治理与城镇发展统筹面临的主要问题及其辩证关系的基础上,以东莞市中部地区的生态园及其所在的寒溪河流域为研究对象,系统探讨了城市水系统规划在流域治理与城镇发展统筹中的协同作用机制。结果表明,以城镇-流域水系统耦合模型为支撑,城市水系统规划及其协同机制可通过空间、设施等要素的协同,实现保障城市及流域防洪排涝安全、保护水环境和节约水资源的目标,促进流域安全与城镇发展的良性互动。

高速公路客货混行交通流元胞传输模型

针对客货混行引发的交通流稳定性下降、交通安全风险增加以及运行效率降低等问题,构建一个多车道客货混行交通流元胞传输模型,从宏观角度研究不同货车渗透率下的高速公路客货混行交通流特性.首先,利用微观车辆跟驰模型,分析均质小汽车和货车交通流的基本图特征,提出不同货车渗透率下的客货混行交通流基本图模型.然后,采用具体参数表征换道、有限加速度造成的道路交通容量下降效应,刻画客货混行交通流中货车对直行和换道流量的影响,采用Logit模型计算多因素影响下的换道交通流量,构建多车道客货混行交通流元胞传输模型.最后,通过高速公路多场景仿真实验验证模型的有效性.研究结果表明:所提出的模型可准确模拟高速公路上的客货混行交通流演变过程;货车渗透率是影响混行交通运行的关键因素,在交通事件导致车道数减少时,货车渗透率超过0.6会导致交通拥堵难以消散.研究成果可为高速公路客货混行交通流特性研究提供分析工具,为客货混行下的交通管理和疏导策略制定提供理论方法.

寒区电动公交充电站选址及定容规划研究

寒区低温环境导致电动公交动力电池容量衰减,充电设施服务范围及规划数量受到影响,给电动公交充电站选址及定容规划带来挑战。为提高电动公交充电站的低温适应性,提出针对寒区电动公交充电站的选址算法及定容模型。首先,在选址规划中,构建充电站渐进覆盖服务半径,利用改进近邻传播聚类算法确定充电站选址点,基于算法聚类中心构建充电站Voronoi图划分充电集群。其次,在定容规划中,构建动力电池低温容量衰减模型,确定寒区电动公交的充电需求;基于容量有限的截尾排队论模型建立充电站有效服务强度、拒绝服务率及充电满意度等约束;引入成本权衡系数,以规划年限内全社会成本最小为优化目标,建立寒区充电站定容规划模型,并设计遗传算法进行求解。最后,以哈尔滨市市区电动公交充电站选址定容规划为例进行分析,算例结果得到9个充电站选址点及其充电集群,以及各充电站的充电机配置数量和各项成本。针对环境温度和成本权衡系数进行灵敏度分析,结果表明:寒区低温环境对充电站的充电机配置数量和各项成本有显著影响,合理权衡充电站和电动公交两者利益有助于提高充电服务满意度,降低全社会成本。

考虑场景差异性的混合车型公交调度优化方法

纯电动公交因其低碳和节能环保的特性,已成为车辆电动化转型的必然选择,但纯电动公交车在实际运营中仍面临低温条件下性能下降和电池老化导致续航里程降低等挑战。考虑在运营中混合使用燃油车和电动车,以弥补纯电动公交车在特定场景下的性能下降,提升公交运营效率和服务质量。本文考虑公交动态运行特征建立公交时刻表分段优化模型,以优化后的车次为输入,构建混合车型运营条件下的公交行车计划编制优化模型,并设计改进的遗传算法实现模型求解。最后,以北京市公交线路为例,选取单线路运营、异地充电及区域集中调度等不同典型运营场景开展案例研究,验证优化模型在差异化运营场景条件下的适用性和优化效果。结果表明,对比本地充电场景,异地充电场景下的运营成本增加5.15%,运营车辆数量增加5.88%;在多线路联合编制行车计划的区域集中调度场景下,运营成本较单线路运营场景降低4.68%;在给定的车型比例阈值下,使用混合车型运营效果优于使用单一车型运营,有效降低运营成本和碳排放。本文研究为公共交通企业结合不同运营场景,制定科学灵活的电动公交运营调度方案提供了重要支撑。

基于通信信号管制的城市空中交叉口设计研究

为确保城市低空空域内无人机规模化运行安全,缓解低空交通运行瓶颈,本文借鉴地面交通较为成熟的研究成果,结合城市低空及无人机运行特色,提出一种基于通信信号管制的城市空中交叉口设计模型。首先,考虑航路构型设计与航路运行主体,构建无人机运行所需的城市低空航路。其次,从进出口道、冲突响应距离2方面对空中交叉口几何结构进行设计,再从进口航道划分、通信信号管制、无人机高度调整3方面对交通组织进行设计,实现对空中交叉口的基本模型设计。最后,设置仿真实验验证该模型的可行性,并分析不同参数组合下的交叉口综合通行效率。实验结果表明:当飞行速度为18 m/s,纵向间隔为50 m,管制信号周期时长为226 s时,综合通行效率达到最佳。本研究可为未来城市空中交通航路网络精细划设与管理提供支撑,增强低空无人机交通的实践性。

基于多目标混合启发式算法的协同无冲突4D航迹规划

为促进基于航迹运行的框架下未来空中交通管理系统的协同决策,本文提出了一种协同无冲突4D航迹规划方法。首先以提高航班效率和航空公司间的公平性为目标,以无冲突为约束构建了一个多目标整数线性优化模型。其次,提出了一种基于基尼系数的指标以量化航空公司间的成本分配公平性。为了提高问题求解效率,采用了基于网格的探测方法以加速冲突检测,并设计了一种多目标混合启发式算法(Multi-objective hybrid-meta-heuristic optimization algorithm,MHMOA),通过结合模拟退火(Simulated annealing,SA)和爬山局部搜索算法来近似最优的非支配解。最后,利用实际航班计划和航路网络数据比较和分析了MHMOA、SA和两种常规多目标优化算法的优化结果。结果表明,MHMOA所获得的非支配解的质量更高、延误更低且航空公司间公平性更优,在3个多目标优化性能指标方面表现优异,可为空中交通管理员提供更详细的决策支持。

考虑快慢车的城轨跨线运营开行方案与时刻表优化

跨线运营是城市轨道交通网络化运营的重要方向,跨线与快慢车组合运营可降低乘客出行时间。本文考虑跨线与快慢车组合模式,构建事件活动图刻画列车运行和乘客出行过程;考虑列车安全运行间隔和列车载客能力等约束,建立以乘客出行时间和列车走行成本最小化为目标的开行方案与时刻表综合优化模型,决策列车运行交路、停站方案、开行频率及各车次在各站的到发时刻;并针对综合优化模型,设计定制的变邻域搜索算法。案例结果表明,在组合模式下,列车走行成本增加了3%,换乘人次降低了82.5%,总乘客和跨线乘客的平均出行时间分别减少了1.3 min和5.3 min,乘客出行效益有明显提升;跨线与快慢车组合模式小幅增加了无需换乘乘客的出行时间,但大幅降低了跨线乘客的出行时间;换乘站换乘走行时间越长,宜开行的跨线列车频率越大,跨线运营降低乘客出行时间的效果越显著。