An exact modelling of the uniform control traffic delay in undersaturated signalized intersections

The average delay experienced by vehicles at a signalized intersection defines the level of service (LOS) at which the intersection operates. A major challenge in this regard is the ability to accurately estimate all the components underlying the overall control delay, including the uniform, incremental and initial queue delays. This paper tackles this challenging task by proposing a novel exact model of the uniform control delay component with a view to enhancing the accuracy of the existing approximate models, notably, the one reported in the Highway Capacity Manual 2010. Both graphical and analytical proofs are employed to derive exact closed‐form expressions for the uniform control delay at undersaturated signalized intersections. The high degree of accuracy of the proposed models is analysed through extensive simulations to demonstrate their abilities to exactly characterize the performance of real‐life intersections in terms of the resulting vehicle delay. Unlike the existing widely adopted uniform delay models, which tend to overestimate the LOS of real‐life intersections, the delay models introduced in this paper have the merit of exactly capturing such a LOS. Copyright © 2016 John Wiley & Sons, Ltd.     

Modeling delay at signalized intersections with channelized right‐turn lanes considering the impact of blockage

This paper presents a probabilistic delay model for signalized intersections with right‐turn channelization lanes considering the possibility of blockage. Right‐turn channelization is used to improve the capacity and to reduce delay at busy intersections with a lot of right‐turns. However, under heavy traffic conditions the through vehicles will likely block the channelization entrance that accrues delay to right‐turn vehicles. If the right‐turn channelization gets blocked frequently, its advantage in reducing the intersection delay is neglected and as a result the channelization lane becomes inefficient and redundant. The Highway Capacity Manual (HCM) neglects the blockage effect, which may be a reason for low efficiency during peak hours. More importantly, using HCM or other standard traffic control methods without considering the blockage effects would lead to underestimation of the delay. To overcome this issue, the authors proposed delay models by taking into account both deterministic and random aspects of vehicles arrival patterns at signalized intersections. The proposed delay model was validated through VISSIM, a microscopic simulation model. The results showed that the proposed model is very precise and accurately estimates the delay. In addition, it was found that the length of short‐lane section and proportion of right‐turn and through traffic significantly influence the approach delay. For operational purposes, the authors provided a step‐by‐step delay calculation process and presented approach delay estimates for different sets of traffic volumes, signal settings, and short‐lane section lengths. The delay estimates would be useful in evaluating adequacy of the current lengths, identifying the options of extending the short‐lane section length, or changing signal timing to reduce the likelihood of blockage. Copyright © 2016 John Wiley & Sons, Ltd.     

A methodology for identifying similar days in air traffic flow management initiative planning

This article describes a methodology for selecting days that are comparable in terms of the conditions faced during air traffic flow management initiative planning. This methodology includes the use of specific data sources, specific features of calendar days defined using these data sources, and the application of a specific form of classification and then cluster analysis. The application of this methodology will produce results that enable historical analysis of the use of initiatives and evaluation of the relative success of different courses of action. Several challenges are overcome here including the need to identify the appropriate machine learning algorithms to apply, to quantify the differences between calendar days, to select features describing days, to obtain appropriate raw data, and to evaluate results in a meaningful way. These challenges are overcome via a review of relevant literature, the identification and trial of several useful models and data sets, and careful application of methods. For example, the cluster analysis that ultimately selects sets of similar days uses a distance metric based on variable importance measures from a separate classification model of observed initiatives. The methodology defined here is applied to the New York area, although it could be applied by other researchers to other areas.     

在斜交十字交叉口内设置车辆待行区的研究

针对斜交十字交叉口存在的安全隐患等问题,提出为锐角进入交叉口的次路车流设置车辆待行区,使支路车流可以分两个阶段通过交叉口．以一级公路为例,运用概率论和排队论计算了车辆待行区所适应的交通量范围,给出了通行能力的计算方法．在不同交通量情况下,比较了普通让行、信号灯和设置车辆待行区三种交叉口控制方式的延误．     

不确定性时滞系统时滞相关鲁棒镇定

讨论了具有状态时滞的数值界不确定性线性系统的时滞相关鲁棒控制问题.将矩阵分解的思想应用于线性时滞系统的控制综合,利用Lyapunov-Krasovskii泛函方法,通过牛顿-莱布尼茨各项相互关系引入"0"阵,得到了系统的一种新的经过状态反馈控制后可鲁棒镇定的、基于LMI的、保守性较低的时滞相关条件.该方法既不需要对原系统进行模型变换,也不需要对交叉项进行界定.用算例说明了该方法的有效性.     

杭州地铁换乘站人员疏散潜在障碍实测研究

分析杭州地铁换乘站凤起路与火车东站站点已经存在和可能存在的客流拥堵情况,设计现场观测布点方案,通过对闸口、换乘通道、扶梯口等节点处乘客行为特征关键数据的现场视频采集和观测统计,定量地给出地铁凤起路换乘站点的安全隐患:约19%低头看手机的乘客会降低客流速度,并会造成拥堵或诱发潜在安全风险;仅16.4%的乘客自愿走扶梯,大量乘客选择乘扶梯,导致从1号线换乘2号线的站厅扶梯处客流大量拥挤。地铁站内一些空间位置设置不合理的附属设施,在一定程度上阻碍客流交会,在客流高峰期会加剧站台客流堵塞程度。基于地铁站内客流路径及拥堵区域分布,挖掘出潜在的建筑结构、设备、导向标识等疏散障碍和安全隐患节点,并提出相应的疏解优化建议。研究结果能够为杭州地铁安全运营优化升级提供可参考的数据基础。     

铁路沿线线性无线传感器网络路由协议研究

针对铁路沿线环境监测对象种类繁多、位置分散的特点,设计一种无线传感器网络用于将传感器采集信息传输至监测中心,该无线传感器网络由传感器节点、轨边汇聚节点、机房汇聚节点及中继节点组成,重点研究提出轨边汇聚节点与机房汇聚节点之间线性无线传感器网络路由协议。鉴于铁路沿线传感器节点采集信息的重要程度不同,该路由协议根据信息重要程度对数据包进行优先级排序。综合考虑网络寿命和信息重要程度,以网络生命周期内传输数据包数量最大化为目标,建立数据包转发模型和数据包排队模型。在网络能耗均衡的前提下,采用减少优先级高的数据包的转发次数和减少优先级高的数据包在轨边汇聚节点的排队时延两种方式,减少优先级高的数据包的总传输时延。仿真结果表明,该路由协议可以显著减少高优先级数据包的传输时延,均衡使用网络能量,最大化网络寿命。     

新建崇礼铁路隧道紧急救援站设置研究

《铁路隧道防灾疏散救援工程设计规范》(TB10020-2017)完善修改了紧急救援站的设计标准及设置要求,即长度大于20 km的隧道或者隧道群应设置紧急救援站。根据条文解释,该处"20km"的长度限定是基于隧道纵坡不大于20‰。但实际工程中,往往存在隧道坡度或者综合坡度大于20‰且隧道长度小于20 km的工况,这种情况下隧道是否设置紧急救援站是亟需解决的问题。结合新建崇礼铁路隧道工程实例,研究隧道纵坡大于20‰且长度小于20 km时是否设置紧急救援站。研究表明,当隧道纵坡大于20‰且隧道长度小于20 km时,是否设置紧急救援站取决于列车上坡折减后的末速度。崇礼铁路陡坡段隧道和隧道群均不需要设置紧急救援站。     

列车晚点情况下的地铁运营调整自组织机制研究

在细致梳理他组织模式下的列车运行调整规则与策略基础上,引入智能体概念,借鉴“沙丁鱼群”运动效应,将邻近两列车间的运行时间距离划分为排斥间隔、协同间隔和吸引间隔,继而建立列车间的协同运动关系。运用仿真技术实现了晚点情况下的列车运行调整自组织算例,论证了自组织调整机制的有效性和应用性。     

基于现行规范的地铁应急照明设计探讨

针对应急照明现行规范在地铁上的设计差异及争议,通过对集中电源、区间疏散照明的配电方案进行对比分析;对电压偏差、应急照明照度的取值、公共区备用照明、区间方向标志灯、吊装标志灯等设置等进行分析探讨,提出目前应急照明设计的一些具体方案及做法。对于集中电源的配电,建议根据消防负荷分布选择在车站两端设置消防小动力箱或疏散照明双切箱;消防应急灯具端子处电压偏差可按额定电压的20%核算;区间疏散照明建议选用10 W灯具,按10 m间距布置;公共区备用照明和吊装标志灯的设置,建议根据当地消防和运营要求决定;各场所的疏散照度值建议按较大值执行。