Autonomous Vehicle Platoons In Urban Road Networks:A Joint Distributed Reinforcement Learning and Model Predictive Control Approach

In this paper, platoons of autonomous vehicles operating in urban road networks are considered. From a methodological point of view, the problem of interest consists of formally characterizing vehicle state trajectory tubes by means of routing decisions complying with traffic congestion criteria. To this end, a novel distributed control architecture is conceived by taking advantage of two methodologies: deep reinforcement learning and model predictive control. On one hand, the routing decisions are obtained by using a distributed reinforcement learning algorithm that exploits available traffic data at each road junction. On the other hand, a bank of model predictive controllers is in charge of computing the more adequate control action for each involved vehicle. Such tasks are here combined into a single framework:the deep reinforcement learning output(action) is translated into a set-point to be tracked by the model predictive controller;conversely, the current vehicle position, resulting from the application of the control move, is exploited by the deep reinforcement learning unit for improving its reliability. The main novelty of the proposed solution lies in its hybrid nature: on one hand it fully exploits deep reinforcement learning capabilities for decisionmaking purposes;on the other hand, time-varying hard constraints are always satisfied during the dynamical platoon evolution imposed by the computed routing decisions. To efficiently evaluate the performance of the proposed control architecture, a co-design procedure, involving the SUMO and MATLAB platforms, is implemented so that complex operating environments can be used, and the information coming from road maps(links,junctions, obstacles, semaphores, etc.) and vehicle state trajectories can be shared and exchanged. Finally by considering as operating scenario a real entire city block and a platoon of eleven vehicles described by double-integrator models, several simulations have been performed with the aim to put in light the main f eatures of the proposed approach. Moreover, it is important to underline that in different operating scenarios the proposed reinforcement learning scheme is capable of significantly reducing traffic congestion phenomena when compared with well-reputed competitors.

Diversity and Application of Herbaceous Flowers in Urban Road Greening in Hefei City

In urban road greening,the planting of ground cover flowers is essential,and herbaceous flowers are an important part.Through the investigation on the diversity of herbaceous flowers in urban road green spaces of Hefei City,the types,colors,application frequency and planting of herbaceous flowers in urban road green spaces were statistically analyzed,and the application forms of herbaceous flowers in the road greening of Hefei City were studied.The characteristics and problems of herbaceous flowers in the road greening of Hefei City were found,and some development suggestions were put forward.

Application Strategy of Green Transportation Concept in Urban Road Design

Urban traffic and urban environmental pollution are important issues that must be taken into account in the process of urbanization,especially in China.Modernization has enabled many developed countries in the west to carry out rational city traffic planning.At the same time,the concept of green transportation has also emerged,integrating low-energy consumption,low pollution,comfort,and safety into urban traffic to effectively solve issues pertaining to traffic and pollution.The concept of green transportation has been widely adopted in China and made popular in many cities,thereby promoting the sustainable development of cities.

Design of Aided Decision-Making Program for Prioritizing Construction Projects in Urban Road Network Planning

The importance and complexity of prioritizing construction projects (PCP) in urban road network planning lead to the necessity to develop an aided decision making program (ADMP). Cost benefit ratio model and stage rolled method are chosen as the theoretical foundations of the program, and then benefit model is improved to accord with the actuality of urban traffic in China. Consequently, program flows, module functions and data structures are designed, and particularly an original data structure of road ...

Integrated reliability of travel time and capacity of urban road network under ice and snowfall conditions

In order to evaluate and integrate travel time reliability and capacity reliability of a road network subjected to ice and snowfall conditions,the conceptions of travel time reliability and capacity reliability were defined under special conditions.The link travel time model(ice and snowfall based-bureau public road,ISB-BPR) and the path choice decision model(elastic demand user equilibrium,EDUE) were proposed.The integrated reliability was defined and the model was set up.Monte Carlo simulation was used to calculate the model and a numerical example was provided to demonstrate the application of the model and efficiency of the solution algorithm.The results show that the intensity of ice and snowfall,the traffic demand and supply,and the requirements for level of service(LOS) have great influence on the reliability of a road network.For example,the reliability drops from 65% to 5% when the traffic demand increases by 30%.The comprehensive performance index may be used for network planning,design and maintenance.

Automatic Extraction of Urban Road Centerlines from High-Resolution Satellite Imagery Using Automatic Thresholding and Morphological Operation Method

The commercial high-resolution imaging satellite with 1 m spatial resolution IKONOS is an important data source of information for urban planning and geographical information system (GIS) applications. In this paper, a morphological method is proposed. The proposed method combines the automatic thresholding and morphological operation techniques to extract the road centerline of the urban environment. This method intends to solve urban road centerline problems, vehicle, vegetation, building etc. Based on this morphological method, an object extractor is designed to extract road networks from highly remote sensing images. Some filters are applied in this experiment such as line reconstruction and region filling techniques to connect the disconnected road segments and remove the small redundant. Finally, the thinning algorithm is used to extract the road centerline. Experiments have been conducted on a high-resolution IKONOS and QuickBird images showing the efficiency of the proposed method.

Traffic Signals Control with Adaptive Fuzzy Controller in Urban Road Network

An adaptive fuzzy logic controller (AFC) is presented for the signal control of the urban traffic network. The AFC is composed of the signal control system-oriented control level and the signal controller-oriented fuzzy rules regulation level. The control level decides the signal timings in an intersection with a fuzzy logic controller. The regulation level optimizes the fuzzy rules by the Adaptive Rule Module in AFC according to both the system performance index in current control period and the traffic flows in the last one. Consequently the system performances are improved. A weight coefficient controller (WCC) is also developed to describe the interactions of traffic flow among the adjacent intersections. So the AFC combined with the WCC can be applied in a road network for signal timings. Simulations of the AFC on a real traffic scenario have been conducted. Simulation results indicate that the adaptive controller for traffic control shows better performance than the actuated one.

Express way and Urban Road Interchange Design Strategy

Highway is an important kind of infrastructure which the transportation sector depends on.The rationality of the interchange design between urban roads and expressways is related to the relieving of urban traffic pressure.Based on the status quo of interchange design between urban roads and expressways,this paper discusses the types and applications of interchange design,hoping to provide reference for the design and construction of highway projects and ensure the rationality of interchange design.

Evolvement regularity of signal control parameters of urban road in cold region

In snow-icy road environment, the survey data indicate that the largest decrease in traffic flow running characters occurs when snow and ice begin to accumulate on the road surface. Saturation flow is decreased by 16% , speed is decreased by 30% , and start-up lost time is increased by 27%. Based on the signal control theory of HCM and Webster, the character values of traffic flow in different urban road environments were investigated, and the evolvement regularity of signal control parameters such as cycle, split, green time, offset, yellow time and red time in snow-icy road environment was analyzed. The impact factors and the changes in the scope of signal control parameters were achieved. Simulation results and practical application show that the signal control plan of road enviromnent without snow and ice will increase the vehicle delay, stop length and traffic congestion in snow-icy road environment. Thus, the traffic signal control system should address a suitable signal control plan based on different road environments.

Logistics Implications of Urban Road Pricing

Urban road pricing schemes are becoming increasingly popular among researchers and politicians as they promise a handle on increasing inner city traffic and economy as well as sustainable improvements for cities facing huge congestion and pollution problems. As in the cases of London and Stockholm, many European cities are going to implement such toll systems, especially as also the European Commission is voting for such pricing schemes in the recent white book on transportation and traffic, This research therefore provides a description of different urban road pricing schemes, their cost implications for city （last mile） transport as well as the decision and management options derived from these schemes for logistics companies. These options are furthermore checked regarding their advantages and disadvantages under the described toll schemes.

Design of Special-shaped Interchange between Expressway and Urban Road in Mountainous Cities

Driven by the rapid economic development,the development of transportation in China has begun to move towards mountainous areas.The climate environment,topography and landform of mountainous cities are different from those of plain areas.In mountainous cities,the area of opposite interchanges between expressways and urban roads is generally large,which has a certain contradiction with the topographic conditions of mountainous cities.Therefore,it is necessary to reasonably design the opposite interchanges between expressways and urban roads in mountainous cities.The author explores and analyzes the factors restricting the special-shaped interchange between expressway and urban road in mountainous cities and the main fbnns of special-shaped interchange,and puts forward a reasonable design scheme,hoping to make a smooth development of the special-shaped interchange in mountainous cities.

Strategies for the Application of BIM Technology in the Collaborative Planning and Design of Urban Roads and Pipelines

Urban road construction and the laying of underground pipelines are both important elements in the improvement of urban infrastructure,while the construction of the two may affect and restrict each other if they are not planned systematically.Therefore,a synergistic design of urban roads and pipelines is needed to ensure the synergy of urban road construction and underground pipeline laying.This paper mainly analyzes the necessity of building information modeling(BIM)technology application in the collaborative planning and design of urban roads and pipelines,and explores the application strategy of BIM technology.

The Application of“Humanized”Concept in Urban Road Design

In order to promote the development of urban roads,enhance urban road design,and fully maximize the role of urban roads,this study first discusses the fundamental requirements of urban road design,the“humanized”concept in urban road design,and the importance of“humanized”urban road design,as well as proposes several“humanized”design strategies for urban roads as references.

中国典型城市交通出行特征及未来道路交通演变研究

为建立适合不同城市特点的交通体系,并明确定位汽车在其中承担的作用,文章首先从外部环境和交通工具两大维度出发,建立了表征城市整体交通出行情况的多层级评价体系;并基于一级指标的得分,对选取的9座中国典型城市的交通出行特征进行了聚类分析,确定了城市的不同类型;然后通过多元回归分析,识别了影响城市道路交通的主要因素;最后通过相关因素变化的情景假设,预测了各城市道路交通效率可能的演变情况,并提出了相关政策建议。

基于街景分析技术的滨江路空间品质研究——以重庆三代滨江路为例

滨江路是滨江城市中极具特征性的线性空间,但针对其特殊的地理环境条件,在特征性指标体系建构及量化评价等方面还有待拓展。结合滨江路环境要素分析构建特征性指标体系,运用基于语义分割的街景分析技术,对重庆市不同时期的3代滨江路展开特征总结与问题剖析。结果表明:1)在指标体系研究方面,应依据不同研究对象和研究目的,有针对性地选取指标;2)在个案层面,由于道路功能的综合提升及城市地形限制的减弱,使新一代滨江路空间品质显著提高;3)跨江立体交通节点对滨江路空间品质影响较大。利用街景技术建立滨江路空间品质评价指标体系,所得结论可为其品质提升提供科学依据。

基于博弈论组合赋权云物元模型的城市道路交通系统风险评价

为保障城市道路交通系统安全运行,降低城市交通事故发生概率,提出了一种基于博弈论组合赋权云物元城市道路交通系统风险评价模型。从城市道路交通系统风险因素出发,结合《城市道路交通管理评价指标体系》,选取实习期驾驶员比例等15个风险评价指标,构建“人-车-道-环”评价指标体系。基于云物元模型,解决评价指标中存在模糊性与随机性的问题,同时采用博弈论将C-OWA有序加权算子处理的专家打分值和改进熵权法求出的权重进行组合优化,围绕待评物元与风险等级之间的隶属度,计算得出风险等级。将该模型应用于中国西部某城市A道路交通系统,展开风险评价,同时将该模型的评价结果与C-OWA云物元模型和熵权云物元模型的评价结果进行对比。结果表明:该模型得出城市A道路交通系统中各指标风险评价结果与实地走访调研结果及实际情况基本一致,且博弈论组合赋权云物元城市道路交通系统风险评价模型更加具有实用性和有效性,可为城市道路交通系统风险评价提供新思路。

基于探地雷达和可拓云的城市道路塌陷易发性评价

随着城市道路网络的不断发达,道路塌陷问题愈加严重。为更好地为道路塌陷灾害实行易发性评价,从而进行预警,此研究将探地雷达数据创新性地融合进评价体系当中,更直观地反映了城市道路塌陷易发程度;并利用变异系数-G1法进行指标的主客观交叉赋权;最后利用可拓云模型的评价方法,很好地反映了具有模糊性和随机性的道路塌陷的客观规律,构建出城市道路塌陷易发性评价模型。并以广州市某市政道路为工程实例,验证了该评价模型的科学有效性。

城市道路交通安全综合评价体系构建及实证研究

为了减少城市道路交通事故的发生概率,提升城市道路安全性,本文进行了城市道路交通安全综合评价体系构建及实证研究。以现阶段城市道路交通特点为基础,构建道路交通安全综合评价体系,分别利用层次分析法与熵权法对评价指标的主观权重与客观权重进行计算,得到综合权重,结合模糊综合评判方法建立城市道路交通安全综合评价模型,获取最终的评价结果。实证研究表明,本文所得结果与专家评价结果一致,验证了该体系的科学性与有效性。

开放式慢行交通系统研究

开放式慢行交通系统是指打破封闭的道路红线、道路绿线及地块用地界限,采用统筹协调的方式,通过“挤、借、换”等措施办法,增加道路慢行交通系统空间布置规模,再通过“调、分、划”等根据功能需要,进行慢行交通系统内部空间再分配、细分配,遵循城市以人民为中心,以人为本,绿色出行,可持续发展的规划设计理念,以保障绿色出行的安全性、便捷性和舒适性为原则,突破传统车本位的空间分配机制,让慢行交通路权与慢行交通实际的多功能需求匹配起来,同时结合景观绿化、海绵城市、多杆合一以及智能交通等建设,使城市道路慢行交通系统成为充足、开放、贯通的公共空间网络,从而满足市民日常户外活动和户外交流的需求。

上海城市快速高架道路健康监测系统的设计与应用——以内环高架(四平路—政本路)“年轻化”工程为例

上海市内环高架,是上海最早建设的城市快速高架道路,建造年代较久,内环高架路浦西段服役年限已达29年,结构存在不同程度病害。针对内环高架“年轻化”改造及后期运营,设计并应用了适配的结构健康监测系统,全时监测车辆动态信息和主梁工作性能等方面,为加强城市快速高架道路桥梁安全运营管理发挥了积极作用,也为同类项目的实施提供了借鉴参考。