Safety modeling for two‐way left‐turn lanes and a procedure to identify two‐way left‐turn lane segments with safety concerns

In the past, two‐way left‐turn lane (TWLTL) median treatments have been frequently used in Florida to inexpensively improve traffic and safety performances. In order to identify factors that may have significant impacts on safety operations in TWLTL sections and to identify TWLTL locations that present existing and future safety concerns, a research project was carried out and results are summarized in the paper. In the research, a three‐year crash history database with crashes and section characteristics from a total of 1688 TWLTL sections all over Florida was developed and used. A negative binomial regression model was developed to determine the statistical relationship between the number of crashes per mile per year and several variables such as traffic volume, access density, posted speed, and number of lanes. In regard to the methodology, in order to identify locations with safety concerns, several steps are needed: development of real crash data distribution, determination of statistical distribution models that better represent the actual crash data, determination of percentile values for the average number of crashes, estimation of crash rates for sections with the same characteristics, estimation of critical values for the variables corresponding to the percentile values for average number of crashes, calculation of tables of critical average annual daily traffic values, and generation of a list of TWLTL locations with critical safety concerns. Results presented in the paper have been used in real applications. Copyright © 2012 John Wiley & Sons, Ltd.     

基于驾驶人特性的双车道跟驰模型稳定性分析

为了研究交通拥堵问题，了解交通拥挤形成的过程及驾驶员自身特性对双车道交通流稳定性的影响.本文基于复杂网络聚类同步理论，对一类基于驾驶员特性的双车道跟驰模型的稳定性进行研究. 通过设计适当的控制器使得基于驾驶人特性的双车道车辆跟驰模型趋于稳定，并得到了模型稳定性的条件.此外，在双车道上的车辆受到随机外部扰动的情形下，利用具有外部扰动的复杂网络自适应H∞ 聚类同步理论，研究了外部扰动情形下基于驾驶人特性的双车道车辆跟驰模型的稳定性.最后，采用MATLAB仿真技术进行数值模拟，验证所设计控制器对双车道交通流稳定性的影响及不同的驾驶员性格特性对交通流运行的影响.     

Shockwave-based queue estimation approach for undersaturated and oversaturated signalized intersections using multi-source detection data

With the progress of information and sensing technologies, estimating vehicular queue length at signalized intersections becomes feasible and has attracted considerable attention. The existing studies provided a solid theoretical foundation for the estimation; however, the studies have some restrictions or limitations more or less. This paper presents a new methodology for estimating vehicular queue length at signalized intersections using multi-source detection data under both undersaturated and oversaturated conditions. The methodology applies the shockwave theory to model queue dynamics. Using data from probe vehicles and point detectors, analytical formulations for calculating the maximum and minimum (residual) queue lengths of each cycle are developed. Ground truth data were collected from numerical experiments conducted at two intersections in Shanghai, China, to verify the proposed methodology. It is found that the methodology has mean absolute percentage errors of 17.09% and 12.28%, respectively, for maximum queue length estimation in two tests, which are reasonably effective. However, the methodology is unsatisfactory in estimating the residual queue length. Other limitations of the proposed models and algorithms are also discussed in the paper.     

城市道路交叉口借道右转车道设置方法

为了弥补交叉口空间布局中对借道右转车道研究的不足,分析了借道右转车辆在两相邻交叉口间的运行过程,将两交叉口间距分为四部分。采用波动理论、考虑驾驶员的操作顺适性以及采用概率论方法,建立了借道右转的右转车道适宜开口位置模型、借道右转的绿化带开口长度模型和路段右转车辆的合流段长度模型,在此基础上得到了实施借道右转的两交叉口最小间距模型。实例分析表明,所得模型符合两相邻交叉口间的交通流运行实际,对于判断两相邻交叉口是否适合于设置借道右转,以及设置借道右转时如何对各构成部分进行分析具有指导意义。     

平面交叉口左转车道的几何设计方法研究

针对平面交叉口左转车道的设计方法进行研究,参考发达国家平交路口安全设计规范,分析现有的设计技术规范中不合理的因素,从左转车道的布置、车道宽度的确定、车道长度的确定、过渡段的设计等几个方面,进行了详细的分析研究,提出了平面交叉口左转车道的几何设计方法。     

路段平均行程时间估计方法

为了有效利用线圈检测数据,精确估计路段平均行程时间,提出了一种路段平均行程时间估计方法。将路段平均行程时间分为平均行驶时间、平均排队时间和平均通过路口时间三部分。考虑线圈埋设的特点,通过估计平均行驶速度得到平均行驶时间。用分段时齐Poisson过程描述车辆驶入路段过程和驶离过程,用Markov排队模型描述车辆排队过程,用生灭过程描述排队车辆数,得到车辆排队模型,计算了路段有、无初始排队的平均排队时间。基于选取与路口相关的饱和流率和平均车长,计算了平均通过路口时间。计算结果表明:平均行程时间估计值与实测值的误差小于12%,说明路段平均行程时间估计方法可行。     

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简单输入输出模型与冲击波分析是研究交通瓶颈问题的两种常用方法,本文着重分析两者的一致性。在数学推导中考虑到达需求与流出率的变化时,两者对于排队和延误的预测结果是一致的。在不同的交通和边界条件下,两者在拥堵形成至消散的任意时刻所得排队长度,拥堵时间等结果均是一致的。以往认为两种方法不一致的研究忽略了一些与背景交通密切相关的基本因素。实例分析说明正是这些基本因素使得这两种分析方法在不同流量－密度关系下都具有一致性。     

浅析隧道车道功能划分

分析了影响车道功能划分的主要因素。以南京长江隧道为例介绍了确定隧道车道功能的计算方法,并给出了南京长江隧道车道划分模型。     

基于 M/G/1模型的停车场出口排队延误

通过对大型停车场高峰时段出口车辆行驶特性的调查研究,选取了车辆排队的出口车头时距以及出口服务时间两个指标。基于两个指标实测特性和 M/G/1排队模型的分析,计算了停车场出口理论平均排队时间。通过实测车辆平均排队时间,对理论模型计算的平均排队时间进行了修正。实例分析表明：排队时间修正模型能够准确地估计排队时间。提出了基于驾驶员容忍度的排队延误分级标准。     

非线性横摇跳跃现象的预报方法

船舶在波浪中的大角度横摇运动、本质上是非线性振动问题。本文以非线性振动理论中的平均法为基础,推演了船模非线性横摇运动的幅频和相频曲线的计算公式,可预报其跳跃现象。与应用新型可控力矩式横摇激振装置的船模试验结果相比较,一致性较好。