Agent-based en-route diversion: Dynamic behavioral responses and network performance represented by Macroscopic Fundamental Diagrams

This paper focuses on modeling agents’ en-route diversion behavior under information provision. The behavior model is estimated based on naïve Bayes rules and re-calibrated using a Bayesian approach. Stated-preference driving simulator data is employed for model estimation. Bluetooth-based field data is employed for re-calibration. Then the behavior model is integrated with a simulation-based dynamic traffic assignment model. A traffic incident scenario along with variable message signs (VMS) is designed and analyzed under the context of a real-world large-scale transportation network to demonstrate the integrated model and the impact of drivers’ dynamic en-route diversion behavior on network performance. Macroscopic Fundamental Diagram (MFD) is employed as a measurement to represent traffic dynamics. This research has quantitatively evaluated the impact of information provision and en-route diversion in a VMS case study. It proposes and demonstrates an original, complete, behaviorally sound, and cost-effective modeling framework for potential analyses and evaluations related to Advanced Traffic Information System (ATIS) and real-time operational applications.     

第三方运行图编制软件在轨道交通线网中的应用

近年来,随着很多城市轨道交通线网的逐步形成,每条线路可能采用不同厂家的信号系统,导致列车运行图编制软件版本众多,给运行图编制人员带来诸多的不便.引进第三方的运行图编制软件,由第三方软件统一铺画完运行图再导入其他ATS中使用,编制人员就可以避免学习多个运行图编制软件,缩短时间,节省人力,提高工作效率.通过实例,证明该项目的可行性.     

故障树分析的二元决策图方法

为了克服故障树方法分析复杂系统存在的不足,引入二元决策图理论,把故障树转化成二元决策图;然后自上而下遍历二元决策图,得到最小割集和顶事件发生的概率.二元决策图转化过程中,基本事件的排序直接影响二元决策图的结构大小.在不改变故障树逻辑关系的前提下,先对故障树进行简化,除去一些冗余的部分;然后从故障树结构重要度的角度,对简化后故障树的基本事件进行排序.实例证明所采用的基本事件排序方法是有效的,能够简化故障树定性和定量分析过程.     

Microscopic driving theory with oscillatory congested states: Model and empirical verification

The essential distinction between the Fundamental Diagram Approach (FDA) and Kerner’s three-phase theory (KTPT) is the existence of a unique gap–speed (or flow–density) relationship in the former class. In order to verify this relationship, empirical data are analyzed with the following findings: (1) linear relationship between the actual space gap and speed can be identified when the speed difference between vehicles approximates zero; (2) vehicles accelerate or decelerate around the desired space gap most of the time. To explain these phenomena, we propose that, in congested traffic flow, the space gap between two vehicles will oscillate around the desired space gap in the deterministic limit. This assumption is formulated in terms of a cellular automaton. In contrast to FDA and KTPT, the new model does not have any congested steady-state solution. Simulations under periodic and open boundary conditions reproduce the empirical findings of KTPT. Calibrating and validating the model to detector data produces results that are better than that of previous studies.     

On the use of Lagrangian observations from public transport and probe vehicles to estimate car space-mean speeds in bi-modal urban networks

The Macroscopic Fundamental Diagram (MFD) has been recognized as a powerful framework to develop network-wide control strategies. Recently, the concept has been extended to the three-dimensional MFD, used to investigate traffic dynamics of multi-modal urban cities, where different transport modes compete for, and share the limited road infrastructure. In most cases, the macroscopic traffic variables are estimated using either loop detector data (LDD) or floating car data (FCD). Taking into account that none of these data sources might be available, in this study we propose novel estimation methods for the space-mean speed of cars based on: (i) the automatic vehicle location (AVL) data of public transport where no FCD is available; and (ii) the fused FCD and AVL data sources where both are available, but FCD is not complete. Both methods account for the network configuration layout and the configuration of the public transport system. The first method allows one to derive either uni-modal or bi-modal macroscopic fundamental relationships, even in the extreme cases where no LDD nor FCD exist. The second method does not require a priori knowledge about FCD penetration rates and can significantly improve the estimation accuracy of the macroscopic fundamental relationships. Using empirical data from the city of Zurich, we demonstrate the applicability and validate the accuracy of the proposed methods in real-life traffic scenarios, providing a cross-comparison with the existing estimation methods. Such empirical comparison is, to the best of our knowledge, the first of its kind. The findings show that the proposed AVL-based estimation method can provide a good approximation of the average speed of cars at the network level. On the other hand, by fusing the FCD and AVL data, especially in case of sparse FCD, it is possible to obtain a more representative outcome regarding the performance of multi-modal traffic.     

铁道列车制动限速

阐明并确立铁道列车紧急制动限速与常用制动限速的涵义、影响因素、核定依据以及不同的确定方式。通过铁道列车紧急制动距离限值与紧急制动限速的数学关系,可以求解不同条件下的列车紧急制动限速值。建立铁道列车紧急制动限速的简化经验公式,并给出各种既有列车特定的相关经验系数。基于常用制动时列车总减速力等于零的极限约束条件,计算并绘制普通货物列车的常用制动限速图。利用图解方法得到我国普通货物列车总制动限速图以及其中的紧急制动限速与常用制动限速的分界转换线。利用相关的简化经验公式及制动限速图可以方便、准确地求出列车具体制动限速值或制订列车制动限速表。     

构建安全和谐货检站的思考

以全国铁路第六次大面积提速调图给货检站带来的新问题为切入点,对加强标准化货检站管理进行探讨,提出强化货检安全管理基础、严格货检作业卡控和运用先进的科技设备3个关键点,最后给出了提高货检安全质量的建议。     

Cooperative traffic control of a mixed network with two urban regions and a freeway

Currently most optimization methods for urban transport networks (i) are suited for networks with simplified dynamics that are far from real-sized networks or (ii) apply decentralized control, which is not appropriate for heterogeneously loaded networks or (iii) investigate good-quality solutions through micro-simulation models and scenario analysis, which make the problem intractable in real time. In principle, traffic management decisions for different sub-systems of a transport network (urban, freeway) are controlled by operational rules that are network specific and independent from one traffic authority to another. In this paper, the macroscopic traffic modeling and control of a large-scale mixed transportation network consisting of a freeway and an urban network is tackled. The urban network is partitioned into two regions, each one with a well-defined Macroscopic Fundamental Diagram (MFD), i.e. a unimodal and low-scatter relationship between region density and outflow. The freeway is regarded as one alternative commuting route which has one on-ramp and one off-ramp within each urban region. The urban and freeway flow dynamics are formulated with the tool of MFD and asymmetric cell transmission model, respectively. Perimeter controllers on the border of the urban regions operating to manipulate the perimeter interflow between the two regions, and controllers at the on-ramps for ramp metering are considered to control the flow distribution in the mixed network. The optimal traffic control problem is solved by a Model Predictive Control (MPC) approach in order to minimize total delay in the entire network. Several control policies with different levels of urban-freeway control coordination are introduced and tested to scrutinize the characteristics of the proposed controllers. Numerical results demonstrate how different levels of coordination improve the performance once compared with independent control for freeway and urban network. The approach presented in this paper can be extended to implement efficient real-world control strategies for large-scale mixed traffic networks.     

SF—350型滑模式水泥混凝土摊铺机的电路原理

介绍了美国ＣＭＩ公司生产的ＳＦ－３５０型滑模式水泥混凝土摊铺机的电路原理、电气图、并对操作按钮功能做了描述。     

故障处理图册的编制

为实现对故障点快速、准确定位,压缩故障延时,编制了故障处理图册。从图册制定标准,具体图册内容及编制意义等方面进行详细介绍,以便更好地指导现场故障处理。