Planning for the unexpected: The value of reserve capacity for public transport network robustness

Public transport networks (PTN) are subject to recurring service disruptions. Most studies of the robustness of PTN have focused on network topology and considered vulnerability in terms of connectivity reliability. While these studies provide insights on general design principles, there is lack of knowledge concerning the effectiveness of different strategies to reduce the impacts of disruptions. This paper proposes and demonstrates a methodology for evaluating the effectiveness of a strategic increase in capacity on alternative PTN links to mitigate the impact of unexpected network disruptions. The evaluation approach consists of two stages: identifying a set of important links and then for each identified important link, a set of capacity enhancement schemes is evaluated. The proposed method integrates stochastic supply and demand models, dynamic route choice and limited operational capacity. This dynamic agent-based modelling of network performance enables to capture cascading network effects as well as the adaptive redistribution of passenger flows. An application for the rapid PTN of Stockholm, Sweden, demonstrates how the proposed method could be applied to sequentially designed scenarios based on their performance indicators. The method presented in this paper could support policy makers and operators in prioritizing measures to increase network robustness by improving system capacity to absorb unexpected disruptions.     

Dynamic activity-travel assignment in multi-state supernetworks

The integration of activity-based modeling and dynamic traffic assignment for travel demand analysis has recently attracted ever-increasing attention. However, related studies have limitations either on the integration structure or the number of choice facets being captured. This paper proposes a formulation of dynamic activity-travel assignment (DATA) in the framework of multi-state supernetworks, in which any path through a personalized supernetwork represents a particular activity-travel pattern (ATP) at a high level of spatial and temporal detail. DATA is formulated as a discrete-time dynamic user equilibrium (DUE) problem, which is reformulated as an equivalent variational inequality (VI) problem. A generalized dynamic link disutility function is established with the accommodation of different characteristics of the links in the supernetworks. Flow constraints and non-uniqueness of equilibria are also investigated. In the proposed formulation, the choices of departure time, route, mode, activity sequence, activity and parking location are all unified into one time-dependent ATP choice. As a result, the interdependences among all these choice facets can be readily captured. A solution algorithm based on the route-swapping mechanism is adopted to find the user equilibrium. A numerical example with simulated scenarios is provided to demonstrate the advantages of the proposed approach.     

基于网络交通分配方法族谱的交通分配 一体化技术与工程应用

为满足交通规划、建设与管理等应用场景对交通分配多样化的需求，结合目前交通分配方 法族谱中的众多模型与方法，本文构建能够满足族谱中所有交通分配特征的一体化交通分配技 术框架，提出交通网络交通分配一体化技术体系，并将该体系嵌入交通分析平台软件“交运之星- TranStar”中。该技术体系包括：“模型关键参数”“交通阻抗函数”“交通网络交通分配基础模型与 快速算法”3部分模块组合的分析模型一体化；面向步行、自行车、机动车及公共交通等多模式交 通网络的分析对象一体化；针对城市土地开发，交通网络建设，交通管理控制，公共交通系统，以 及交通政策制定等应用场景一体化。选取南京市道路网络和公交网络进行实证分析。结果表 明，本文提出的交通分配一体化技术具有处理超万节点多模式交通网络的能力，对各类交通模 式、典型业务场景的分析结果可为城市交通系统规划、建设与管理提供决策支持。     

Compromising system and user interests in shelter location and evacuation planning

Traffic management during an evacuation and the decision of where to locate the shelters are of critical importance to the performance of an evacuation plan. From the evacuation management authority’s point of view, the desirable goal is to minimize the total evacuation time by computing a system optimum (SO). However, evacuees may not be willing to take long routes enforced on them by a SO solution; but they may consent to taking routes with lengths not longer than the shortest path to the nearest shelter site by more than a tolerable factor. We develop a model that optimally locates shelters and assigns evacuees to the nearest shelter sites by assigning them to shortest paths, shortest and nearest with a given degree of tolerance, so that the total evacuation time is minimized. As the travel time on a road segment is often modeled as a nonlinear function of the flow on the segment, the resulting model is a nonlinear mixed integer programming model. We develop a solution method that can handle practical size problems using second order cone programming techniques. Using our model, we investigate the importance of the number and locations of shelter sites and the trade-off between efficiency and fairness.     

自校正极点配置解耦控制器

本文提出的多变量自校正控制器，完成了对控制系统的闭环及极点配置和动态解耦，且能使系统对阶跃给定值实现稳态无差跟踪。本算法适用于最小相位系统、非最小相位系统以及各道时延不等的系统。数字仿睦证实了本算法的良好性能。     

对多路径交通分配的节点分配算法的讨论

针对文[1]中的多路径交通分配的节点分配算法存在的问题进行了讨论,提出了合理的修正方法,该方法需要路径的列举.最后给出了修正方法的应用实例并与Dial算法进行了比较.     

外派海员的工作压力探讨

工作压力是影响海员身心健康和海上安全的重要因素之一.外派海员是一个特殊的职业群体,其工作压力构成更为复杂,本文从外派船员压力的形成和管理进行探讨,并提出相关建议.     

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提出了一个在有高速公路和城市干道的组合路网中设置可变信息标志(CMS)组位置的最优化模型．与文献中现有的模型相比较，本文的模型有效地达到了实际规模道路网络计算复杂性问题和确保求解模型的质量之间很好的平衡． 本模型具有三个不同的特征：(1)认为在路网中设置安装可变信息标志(CMS)系统是一个必须同时考虑现在和未来需要和利益的典型的规划问题；(2)评估由于在路网中设置了可变信息标志(CMS)系统而带来的交通效益是通过具有不同交通分布型态的多个时段来完成的；(3)考虑了在不同的路段上和时段内交通事件的特征本质上是变化的因素．本文还进行了敏感性分析，用以检验在各种不同的交通输入参数中，如交通需求、交通事件特征值、以及驾驶员交通行为的不确定性对可变信息标志系统(CMS)在路网中的最优设置的潜在影响．最后，本模型应用于加拿大多伦多的401高速公路和辅道组成的混合道路系统，并且对CMS系统设置结果进行了检验．     

基于Fisk运量随机配流的交通信息最优发布水平确定研究

本文借助Fisk运量随机配流模型建立一个简单二层规划模型来研究交通信息的最优发布水平，通过模型分析得出一些重要结论。在非拥挤交通网络中，信息发布不产生外部效果，信息系统应发布全部信息；在严重拥挤的交通网络中，产生正的外部效果，信息系统应发布全部信息；在一般拥挤网络中，可能产生正的外部效果，也可能产生负的外部效果，应根据具体情况选择合适的信息发布水平。     

基于行程时间可靠性的多类用户交通分配模型

分析了路网在随机因素作用下造成的出行者行程时间的不确定性.假设出行者基于期望行程时间和行程时间可靠性的均衡选择路径,根据出行者对待行程时间可靠性的不同态度,将其路径选择行为分类,建立了基于行程时间可靠性的多类用户交通分配的变分不等式模型.给出了模型的对角化算法.对一个小型测试网络的计算结果表明,该模型能够反映出行者在不确定环境下的路径选择行为.