信号周期对道路交叉口延误和通行能力的影响研究

以典型十字信号控制交叉口为研究对象,基于工作日早高峰时段(7:00—8:00)实际调查的交通量、渠化方案、信号相位等数据,利用Synchro软件研究信号周期对交叉口通行能力和延误的影响规律.研究发现:随着信号周期的增加,在渠化方案和流量不变的情况下,交叉口的延误和通行能力也随之增加.当交叉口的通行能力或信号周期一定时,渠化方案II("左转+直右+右转")优于渠化方案I("左转+直行+右转").当渠化方案和信号周期一定时,随着右转专用车道转入直右共用车道的车辆比例增加,交叉口的通行能力降低,延误增加.研究结果可为交通管理部门决策者提供决策支持,缓解城市交通瓶颈处的拥堵.     

象限绕行平面交叉交通组织方式研究

针对道路平面交叉口左转交通给交叉口通行能力带来的影响,介绍近年来国外采用的象限绕行平面交叉。通过在平面交叉的某一区域内设置专用左转车道,消除大型平面交叉左转车流对直行交通的干扰;基于临界车道流量法建立传统十字形平面交叉和象限绕行平面交叉计算模型,分析得到左转专用车道的最佳位置,结合实例分析验证该方法的合理性。     

基于VISSIM的A类交叉口优化模型与应用

在城市主干道与主干道相交的A类交叉口内,当左转公交车交通量较大并与其他交通混合行驶时,由于其转弯半径较大,一方面会影响小汽车的通行效率,另一方面也会对直行车辆产生较大影响,进而严重影响交叉口的通行能力,具有较大的交通隐患。因此,以左转公交为题目,提出一种A类交叉口优化模型。该模型采用四相位的配时方法,通过设置公交车辆与社会车辆分别行驶的左转车道的方式,使冲突分离,并通过VISSIM仿真软件,结合具体实例检验了仿真优化模型的适用性。     

基于交通设计理念的道路平交口交通阻塞问题的道路精细化设计

基于交通设计理念,从交通阻塞问题与特征入手,进而对交通阻塞问题成因进行研究,然后通过交叉口车道匹配设计、合理设置掉头车道、通过交通标线加强交通疏导和慢行交通一体化设计来改善交通基础设施和通行条件,以此增强道路平面交叉口的交通供给能力,从而提高交叉口通行能力,改善交叉口阻塞问题。     

出口道短车道对信号控制交叉口通行能力影响

研究出口道短车道在不同交通条件和道路几何条件下对道路交通能力的影响,可以进一步完善交叉口通行能力计算理论体系,对工程设计给出理论依据。介绍了相关研究背景,交叉口出口道短车道对信号控制交叉口通行能力的修正。最后从短车道长度、有效绿灯时间、路段与进口道饱和流量差、交通流基本参数关系模型等因素,分析了出口道短车道对通行能力的影响程度。     

城市道路平面交叉口优化设计

论述了城市道路平面交叉口优化设计,通过实例运用交通标志、标线和实体设施以及局部展宽进口端,设置左、右转专用车道等措施来减少车与车、人与车冲突或明确分开冲突,形成一个有序的道路交通系统,真正实现城市道路的安全、通畅,并实质性地提高了整个城市的交通能力。     

城市灯控平面交叉口机动车进出口车道的平衡

叙述了城市灯控平面交叉口机动车进出口车道平衡的概念及评价指标平衡度θ。介绍了通过对交叉口进口、出口车道断面通行能力计算得到平衡度θ的计算方法。以南京市太平北路—珠江路十字形交叉口为例,通过实地勘测的参数,计算得到平衡评价指标平衡度θ,认为此交叉口进出口车道基本平衡。这种评价方法不仅可以帮助分析发现交叉口车道数设置的问题而进行改进,而且可以为新建或改建交叉口提供参考依据。     

拓宽分流渠化平交口的优越性

<正> 拓宽分流平交口的交通组织特点是通过局部拓宽交叉口范围,设置专门的左转弯候驶车道、右转弯车道,从而使各种不同流向的机动车,能在绿灯信号下“各行其道”通过交叉口。由于这种交通组织方式,右转车     

城市交叉口设计

城市道路网的高效通行能力，受到交叉口的制约。城市交叉口的正确设计，能促进城市交通发展。探索多层次交通结构、提出解决交叉口交通拥挤对策。     

重庆市城市道路信号交叉口机动车交通特性研究

在城市道路网中,平面交叉口是城市道路通行能力和交通安全的瓶颈。由于社会经济、文化背景、道路环境等的不同,不同地区的交通活动表现出不同的行为特征。本文采用视频技术和人工观测技术,研究了重庆市机动车在市政道路信号平面交叉口时的交通特征,为交叉口立体空间设计和信号配时优化提供了基础数据。     

道路平面交叉口次路远引几何参数设置及通行效率研究

次要车流的左转和直行对交叉口车辆运行影响较大,特别是主路交通流量较大时尤为明显,通过次要道路车流远引的方式可以减少交叉口车辆冲突,有利于提高交叉口运行效率。分析了平面交叉口次路远引适用条件与车流组织方法,以延误最小为目标,构建了远引回转车流掉头位置、远引车辆掉头排队车道长度、远引掉头处开口长度与宽度等关键几何参数计算模型,提出了次路远引交叉口延误和通行能力等计算方法。结合实例验证了上述方法的可行性,仿真显示,在一定条件下平面交叉口次路远引可有效减少信号相位数和车辆平均延误,表明了平面交叉口次路远引的交通组织方法对优化城市道路交叉口设计有较好的应用价值。     

城市公交专用道设置方法及其适应性研究

公交专用道是提高公交运行效率的重要手段之一。对沿路外侧机动车道设置公交专用道、沿路内侧机动车道设置公交专用道和沿路中间机动车道设置公交专用道3种城市道路路段公交专用道设置形式和适应性进行了分析。对直行、左转、右转3类交叉口公交进口道的设置方法进行了研究。最后对快速公交系统专用道及其站点设置形式、特点进行了总结。     

Effect of secondary elements on bridge structural system reliability considering moment capacity

Secondary elements such as barriers, sidewalks, and diaphragms may increase the load carrying capacity of girder bridges. This in turn affects reliability. The objective of this study is to evaluate the potential benefit of secondary elements on the system reliability of girder bridges, if these elements are designed with the structural system to participate resisting vehicular live loads. Simple span, two lane structures are considered, with composite steel girders supporting a reinforced concrete deck. For structural analysis, a finite element procedure is developed that combines a grillage model of the bridge deck with solid elements for edge-stiffening effects. Random variables considered are composite girder, barrier, and sidewalk flexural strengths (each in turn composed of many random variables), load magnitude (dead load and truck traffic live load), and live load position. System resistance parameters are estimated with a point integration method. System resistance is evaluated in terms of maximum load carried at ultimate capacity. It was found that the interaction of typical secondary element combinations has a varying effect on system reliability, depending on element stiffness, bridge span, and girder spacing.     

Measuring traffic lane‐changing by converting video into space–time still images

Empirical data is needed in order to extend our knowledge of traffic behavior. Video recordings are used to enrich typical data from loop detectors. In this context, data extraction from videos becomes a challenging task. Setting automatic video processing systems is costly, complex, and the accuracy achieved is usually not enough to improve traffic flow models. In contrast “visual” data extraction by watching the recordings requires extensive human intervention. A semiautomatic video processing methodology to count lane‐changing in freeways is proposed. The method allows counting lane changes faster than with the visual procedure without falling into the complexities and errors of full automation. The method is based on converting the video into a set of space–time still images, from where to visually count. This methodology has been tested at several freeway locations near Barcelona (Spain) with good results. A user‐friendly implementation of the method is available on http://bit.ly/2yUi08M .     

快速路出口匝道交织区交通组织方法研究

城市快速路出口匝道与下游交叉口归纳成3种交通组织方法,即常规交织布置、车道转向置换及交替放行控制。利用微观交通仿真软件进行回归分析,提出城市快速路典型衔接交织段的延误计算公式,可对交织区运行延误进行量化计算。最后结合工程实例对3种方法的运行效果进行比较,提出快速路出口匝道设计和管理的方法。     

Optimizing schedule for improving the traffic impact of work zone on roads

Many different types of construction projects set up work zones on roads. Especially in urban areas, lane closures as a result of work zones have a considerable impact on local traffic. However, for a construction project that consists of several work zones and several work crews, the traffic impact may be improved by appropriate scheduling. Therefore, this paper proposed a scheduling model based on the route-changing behavior of road users. The proposed model calculates the traffic delay of vehicles by microscopic simulation, and applies team ant colony optimization to search for a near-optimal schedule. The project planner then ensures that the contractor executes the activities according to the near-optimal schedule. The proposed model is applied to schedule a sewer system construction project in a city. The results of our study indicate that with our proposed model the total traffic delay is reduced by 11.1% when compared with a schedule proposed by the project planner.     

Fuzzy Cellular Automata Model for Signalized Intersections

At signalized intersections, the decision‐making process of each individual driver is a very complex process that involves many factors. In this article, a fuzzy cellular automata (FCA) model, which incorporates traditional cellular automata (CA) and fuzzy logic (FL), is developed to simulate the decision‐making process and estimate the effect of driving behavior on traffic performance. Different from existing models and applications, the proposed FCA model utilizes fuzzy interface systems (FISs) and membership functions to simulate the cognition system of individual drivers. Four FISs are defined for each decision‐making process: car‐following, lane‐changing, amber‐running, and right‐turn filtering. A field observation study is conducted to calibrate membership functions of input factors, model parameters, and to validate the proposed FCA model. Simulation experiments of a two‐lane system show that the proposed FCA model is able to replicate decision‐making processes and estimate the effect on overall traffic performance.     

基于交通延误最小的道路养护策略优化

道路养护常常需要关闭相应的机动车道 ,因而会产生新的交通延误。为减少四车道道路养护时所带来的交通延误 ,论文建立了基于交通延误最小的道路养护策略的整数规划优化模型 ,其中目标函数为路网总的交通延误最小 ,约束条件为总的可用工作时间 ;并通过具体的实例对模型进行了验证。在整数规划优化的基础上 ,论文还讨论了通过引入交通标志对交通流进行诱导从而进一步减少交通延误的可能性     

An Analytical Approach for Estimating the Highway Capacity Manual Signalized Intersection Delay Variability

Abstract: This article developed a generalized model incorporating three stochastic input variables in the Highway Capacity Manual (HCM) delay equation and analyzed the delay variability explicitly considering variations in key input variables including traffic volume, effective green time, and saturation flow rate. An integration method was used for calculations of mean and variance of the HCM delay. Unlike the previous Expectation Function Method, the proposed integration method can be applied for both undersaturated and oversaturated situations. The applicability of the proposed methodology was demonstrated through a hypothetical case study for a lane group at an isolated signalized intersection. The effects of stochastic variables (e.g., traffic volume, saturation flow rate, and effective green time) and correlations among these variables in the HCM delay were examined.     

Modeling adaptive platoon and reservation-based intersection control for connected and autonomous vehicles employing deep reinforcement learning

As a cutting-edge strategy to reduce travel delay and fuel consumption, platooning of connected and autonomous vehicles (CAVs) at signal-free intersections has become increasingly popular in academia. However, when determining optimal platoon size, few studies have attempted to comprehensively consider the relations between the size of a CAV platoon and traffic conditions around an intersection. To this end, this study develops an adaptive platoon-based autonomous intersection control model, named INTEL-PLT, which adopts deep reinforcement learning technique to realize the optimization of multiple dynamic objectives (e.g., efficiency, fairness, and energy saving). The framework of INTEL-PLT has a two-level structure: The first level employs a reservation-based policy integrated with a nonconflicting lane selection mechanism to determine the lanes’ releasing priorities; and the second level uses a deep Q-network algorithm to identify the optimal platoon size based on real-time traffic conditions (e.g., traffic density, vehicle movement, etc.) of an intersection. The model is validated and examined on the simulator Simulation of Urban Mobility. It is found that the proposed model exhibits superior performances on both travel efficiency and fuel conservation as compared with state-of-the-art methods in three typical traffic conditions. Moreover, several in-depth insights learned from the simulations are provided in this paper, which could better explain the relation between platoon size and traffic condition.