城市道路平面交叉口安全评价研究

城市平面交叉口是城市交通冲突和事故频繁发生的地点。文章针对城市道路平面交叉口的交通安全现状,分析了平面交叉口的安全影响因素,提出引入事故率和冲突率为评价指标,建立了灰色理论评价方法,为城市道路平面交叉口的安全治理提供理论支持。     

广西公路项目平交式工程安全评价探讨

文章介绍了公路项目平面交叉口工程安全评价的目的,分析了影响公路项目平面交叉口工程安全的因素,并以广西来马高速马山南互通出口与G210公路平交口项目为工程实例,从平纵线形、视距、交叉口间距、交通工程、施工方案等方面对公路项目平交式工程进行安全评价。     

平面信号控制交叉口交通优化设计方法研究 ——以盐城市胜利路与海阔路交叉口为例

通过对平面信号控制交叉口交通优化设计,对提高交叉口通行能力有着重要作用.本文以盐城市胜利路与海阔路交叉口为例,针对分析交叉口现状交通量、交叉口渠化现状、混合交通冲突点,信号配时现状,提出改善措施,提高交叉口的通行能力和安全水平.     

市政道路平面交叉口的交通组织设计

市政道路平面交叉口处路况复杂且多变,为了更好地建设市政道路平面交叉口,做好交叉口的交通组织设计,对市政道路的交叉口分类进行介绍,分析各类交叉口的通行能力,对交叉口的交通路径优化方法进行分析。在此基础上,提出市政道路平面交叉口渠化设计策略,为改进城市交通组织方式、改善城市道路平面交叉口交通拥堵状况提供思路和方法。     

基于VISSIM的平面交叉口交通仿真与改善研究

平面交叉口是交通系统中极易发生拥堵的地方,运用先进的仿真软件VISSIM对交叉口进行改善设计具有较强的优势。文章在分析VIS-SIM仿真软件原理的基础上,提出了平面交叉口的改善方法,并以兰州市建宁路与宝石花路交叉口为例进行了交叉口改善与仿真分析。研究结论对城市平面交叉口改善设计具有一定的借鉴意义。     

城市平面交叉口汽车排放优化策略研究

文章针对城市平面交叉口交通污染严重的问题,分析城市平面交叉口交通及行为特性、影响机动车排放的相关因素,从平面交叉口交通规划、交通控制二个方面阐述汽车排放优化措施。     

平面信号交叉口设计优化方法探析

平面信号交叉口是城市交通中非常重要的环节。但现阶段的平面信号交叉口仅仅能够满足现有的交通流量,随着人口和车辆的不断增加,必须对平面信号交叉口设计进行优化。鉴于此,在分析平面交叉口交通流运行特性的基础上,提出了平面交叉口设计优化方法,以期能够在一定程度上促进交通的发展和城市化进程。     

平面交叉口渠化设计工程应用

结合深圳市宝安区具体的工程案例,从渠化方法及渠化改造内容,对平面交叉口的渠化设计做了详细阐述,有助于平面交叉口的渠化在实际中的工程应用。     

位移型两相位交叉口相位设计及交通组织分析

传统交叉口优化研究多从“建设”和“管理”两方面双管齐下，在具体实施过程中取得了一定效果但难以突破通行能力的限制。文章创造性的提出位移型两相位交叉口的概念，一方面在交叉口的物理结构方面进行优化设计，探索了三类共7种位移交叉口形式；另一方面对位移型两相位平面交叉口的配套交通组织进行分析研究和优化设计，提出了直行同步和直行异步的两相位设计方法，并对位移型两相位交叉口的快慢交通组织进行了分析和研究。研究结论显示位移型两相位交叉口通过减少相位，交叉口通行效率更高；交叉口冲突得到充分分离，相互干扰减少；交叉口排队机会增多，交叉口运行稳定性更高。     

城市错位交叉口信号控制的优化

错位交叉口作为一类特殊的平面交叉口,如何实现其交通信号的合理控制一直是讨论的热点问题.提出将错位交叉口作为一个大型交叉口进行三相位信号控制,同时以交叉口通行能力最大为优化目标,对其信号控制配时进行优化.并且用实例证明了方法的优越性.     

A programmable calculation procedure for number of traffic conflict points at highway intersections

Traffic movement conflict points at intersections are the points at which traffic movements intersect (including crossing, merging, and diverging). Numbers and distribution of different types of conflict points are used to evaluate intersection access management designs and safety performance. Traditionally, the determination of the numbers of conflict points for different traffic movements is based on manual methods, which causes the difficulty for computerized procedures to evaluate safety performance of different access management designs. Sometimes, a programmable calculation procedure may provide more effective solutions as compared with manual methods. This paper presents a programmable calculation procedure for the determination of the numbers of conflict points, which could be used as a basis for a computerized procedure. Concepts of virtual movement lanes and intersection quadrants are introduced to specify types of intersections, traffic lane configurations, and traffic movement regulations. Calculation models, based on such concepts, for traffic movement conflict points at signalized and unsignalized intersections can be obtained. In support of the procedure, case studies are presented in the paper. The procedure presented in the paper can be programmed into a computer program for the purpose of a computerized evaluation of intersection safety and design performance of different access management or control approaches. Copyright © 2012 John Wiley & Sons, Ltd.     

非灯控交叉口交通安全状况评价

非灯控交叉口是交通流中的节点,对非灯控交叉口的交通安全状况进行评价具有导向性意义。文章针对交叉口管控存在的问题,提出了交通安全状况评价原则和主要方法,阐述了非灯控交叉口交通安全的影响因素,并通过对沈阳市刘家窑十字交叉口进行交通安全状况评价,提出了具体的交叉口交通安全改善措施,以提高非灯控交叉口的交通安全性。     

Traffic conflict models to evaluate the safety of signalized intersections at the cycle level

The safety of signalized intersections has often been evaluated at an aggregate level relating collisions to annual traffic volume and the geometric characteristics of the intersection. However, for many safety issues, it is essential to understand how changes in traffic parameters and signal control affect safety at the signal cycle level. This paper develops conflict-based safety performance functions (SPFs) for signalized intersections at the signal cycle level. Traffic video-data was recorded for six signalized intersections located in two cities in Canada. A video analysis procedure is proposed to collect rear-end conflicts and various traffic variables at each signal cycle from the recorded videos. The traffic variables include: traffic volume, maximum queue length, shock wave characteristics (e.g. shock wave speed and shock wave area), and the platoon ratio. The SPFs are developed using the generalized linear models (GLM) approach. The results show that all models have good fit and almost all the explanatory variables are statistically significant leading to better prediction of conflict occurrence beyond what can be expected from the traffic volume only. Furthermore, space-time conflict heat maps are developed to investigate the distribution of the traffic conflicts. The heat maps illustrate graphically the association between rear-end conflicts and various traffic parameters. The developed models can give insight about how changes in the signal cycle design affect the safety of signalized intersections. The overall goal is to use the developed models for the real-time optimization of signalized intersection safety by changing the signal design.     

Crash analysis at intersections in the CBD: A survival analysis model

Enhancing the safety level of urban roads especially in CBDs is paramount. Due to a large number of intersections in what is usually a grid road system in the CBDs, we investigate crashes occurring in and around an intersection. The question of interest in this study is: does the nature of crashes at intersections differ from those of the roads at midblock? Stated more precisely, considering the intersection as a reference point, does the distance to the reference point (i.e. midblock locations on the roads) correlate with different types of crashes compared to that of the intersection? A right answer can lead traffic engineers and safety auditors to propose different safety measures at intersections and the midblock locations. As a pilot study, we collected the last 9 years crash data of the CBD of Melbourne, Australia. For the first time, we employ Survival Analysis models -including Exponential, Weibull, and Log-logistic- to investigate a space-dependent phenomenon (i.e. accidents at proximity to the intersection). Of the outcome, highlights are: (i) police presence at busy intersections during busy night outs and weekends highly improves the pedestrian safety (ii) raised crossings at midblock locations lower likelihood of crashes of pedestrians as well as cars, (iii) lighting conditions at intersections must be watched and kept at a high level. (iv) Severity, likelihood, and location have no known association with the level of congestion. In other words, safety is first, always and everywhere. The results can be of interest to traffic authorities and policy makers in reinforcing traffic calming measures in the cities. The codes developed in this study are made available to the research community to be used in further studies.     

基于潜在冲突量的交叉口安全评价方法研究

文章提出了潜在冲突量的概念,并对其进行了分类,通过车速、交通量、车道宽度等易获取的交通参数来推算交叉口潜在冲突量,引入混合交通当量,将潜在冲突量与混合交通当量比值作为交叉口安全评价的指标,并结合桂林市的9个交叉口进行了安全程度的评价。     

Optimal distance between two branches of uncontrolled split intersection

This work examines the possibility of splitting an uncontrolled “X” intersection into two adjacent uncontrolled “T” intersections. This splitting aims to improve both the movement and safety of traffic. The problem addressed in this work is how to determine the optimal distance between the two adjacent T intersections. The best type of split, based on previous studies, is the one in which vehicles approach first the right turn and then the left turn in both directions of travel. The main conclusions drawn in this work refer to this preferred type. The optimal distance is arrived at on the basis of an objective function of minimal delay subject to blocking queues, passing (another vehicle) probabilities, budget limitations and safety threshold. The input data consist of 12 traffic volumes associated with all the traffic movements of an X intersection. The main findings are: (a) under a medium level of traffic volume, the blocking queue lengths are of the order of hundreds of meters and are very sensitive to the increase of volume toward and beyond saturation flow; (b) the passing probability function along the road segment between the two adjacent T intersections increases with the length of the segment and stabilizes at a length of a few hundred meters; (c) there is a relationship between accident frequency (accident rate and density) and the distance between the split intersections. An example of this relationship is introduced; and (d) the optimal distance between the two adjacent T intersections is found not only theoretically, but also practically for possible implementations.     

Noise level in the vicinity of signalized roundabouts

The analysis, assessment and estimation of noise levels in the vicinity of intersections is a more complex problem than a similar analysis for roads and streets. This is due to the varied geometry of the intersections, differences in the loads of individual movements, participation of heavy vehicles and mass transport vehicles, as well as the various types of traffic management and traffic control. This article analyses the influence of intersection type and traffic characteristics on the noise levels in the vicinity of classic channelized intersections with signalization, roundabouts and signalized roundabouts. Based on the conducted measurements, it has been established that, with comparable traffic parameters and the same distance from the geometric centre of the intersection, the L_Aeq value for signalized roundabouts is 2.5–10.8 dB higher in comparison to classic channelized intersections with signalization and 3.3–6.7 dB higher in relations to the analysed roundabout. Additionally the differences between L_Aeq levels at individual entries at the same signalized roundabouts may reach the value of approximately 4.5 dB. Such situation is influenced by differences in the intersection geometry, diameter of the intersection’s central island, traffic flow type, traffic management at the entries and traffic volume, especially the amount and traffic movements of multiple axle heavy vehicles. These factors have been analysed in detail in relation to signalized roundabouts in this paper.     

Traffic volume forecasting based on radial basis function neural network with the consideration of traffic flows at the adjacent intersections

The forecasting of short-term traffic flow is one of the key issues in the field of dynamic traffic control and management. Because of the uncertainty and nonlinearity, short-term traffic flow forecasting could be a challenging task. Artificial Neural Network (ANN) could be a good solution to this issue as it is possible to obtain a higher forecasting accuracy within relatively short time through this tool. Traditional methods for traffic flow forecasting generally based on a separated single point. However, it is found that traffic flows from adjacent intersections show a similar trend. It indicates that the vehicle accumulation and dissipation influence the traffic volumes of the adjacent intersections. This paper presents a novel method, which considers the travel flows of the adjacent intersections when forecasting the one of the middle. Computational experiments show that the proposed model is both effective and practical.