Neues verkehrswissenschaftliches Journal - Ausgabe 19
Neues verkehrswissenschaftliches Journal - Ausgabe 19

Author: Di Liu

Publisher: BoD – Books on Demand

Published: 2017-07-11

Total Pages: 202

ISBN-13: 3744841030

DOWNLOAD EBOOK

Rail-bound transport in urban areas plays an important role in public transport. Given its urban setting, urban rail-bound transport can be significantly influenced by the interfering road traffic around it. Considering the capacity and operation quality of urban rail-bound transport influenced by road traffic in various urban mixed traffic zones, it'very important to investigate and include the road traffic influences for capacity research on urban rail-bound transport. In this dissertation, two approaches are developed to model the road traffic influences according to the analysis of the interactions between urban mixed traffic in various mixed traffic zones. As an important intermediate result, the newly-developed waiting time function is determined to adapt to an urban rail-bound system with consideration of external influences. Furthermore, an algorithm is developed in the model with an event-driven system to simulate the interactions among urban mixed traffic in various mixed traffic zones. This algorithm is used to assess the significance of mixed traffic impacts and derive the primary results for capacity research.

Neues verkehrswissenschaftliches Journal - Ausgabe 22
Neues verkehrswissenschaftliches Journal - Ausgabe 22

Author: Weiting Zhao

Publisher: BoD – Books on Demand

Published: 2018-01-23

Total Pages: 142

ISBN-13: 3746035015

DOWNLOAD EBOOK

With the increasing traffic demand and limited infrastructure expansion, railway operation becomes more susceptible to the operational disturbances. In order to ensure a robust railway operation, a proactive dispatching algorithm in dynamic circumstances under the consideration of random disturbances is necessary. In this study, an operational risk map will be firstly produced: by simulating considerable amount of disturbed scenarios generated in a Monte-Carlo scheme and calculating the corresponding expected negative impacts, different levels of operational risk will be assigned to each block section in the investigated network. Within a rolling time horizon framework, conflicts are detected with the inclusion of risk-oriented disturbances in each block section, and the near-optimal dispatching solutions are calculated by using Tabu search algorithm. Finally, three indicators including total weighted waiting time, the number of relative reordering and average absolute retiming, are chosen to testify the effectiveness and advantages of the proposed dispatching algorithm. The sensitivity analysis of dispatching-related parameters is conducted afterwards to investigate the most appropriate relevant parameters for the specific studied area. The proposed algorithms are expected to be capable of automatically producing near-optimal and robust dispatching solutions with sufficient punctuality achieved.

Neues verkehrswissenschaftliches Journal - Ausgabe 26
Neues verkehrswissenschaftliches Journal - Ausgabe 26

Author: Yong Cui

Publisher: BoD – Books on Demand

Published: 2018-10-25

Total Pages: 198

ISBN-13: 3752855207

DOWNLOAD EBOOK

Simulation methods are widely-used in the field of railway planning and operations. However, the various tools are all lacking with respect to the standards they utilise as well as their published interfaces. For an end-user, the basic mechanism and the assumptions built into a simulation tool are unknown, which means that the true potential of these software tools is limited. One of the most critical issues is the lack of the ability of users to define a sophisticated workflow, integrated in several rounds of simulation with adjustable parameters and settings. This book develops and describes a user-based, customisable platform. As the preconditions of the platform, the design aspects for modelling the components of a railway system and building the workflow of railway simulation are elaborated in detail. Based on the model and the workflow, an integrated simulation platform with open interfaces is developed. Users and researchers gain the ability to rapidly develop their own algorithms, supported by the tailored simulation process in a flexible manner. The productivity of using simulation tools for further evaluation and optimisation will be significantly improved through the user-adaptable open interfaces.

Neues verkehrswissenschaftliches Journal - Ausgabe 18
Neues verkehrswissenschaftliches Journal - Ausgabe 18

Author: Jiajian Liang

Publisher: BoD – Books on Demand

Published: 2017-08-18

Total Pages: 190

ISBN-13: 3744840107

DOWNLOAD EBOOK

A railway system is a complex system. With the assistance of a railway operation control system, railway traffic is managed according to an operation plan. During the operation process, especially in railway networks with complex topology and high traffic flow, disturbances are likely to occur, which may result in severe deviations of train movements from the pre-designed operation plan. Once conflicts have occurred or potential conflicts between trains have been detected, suitable dispatching actions should be executed to minimize the negative impacts of the disturbances. In order to support dispatchers, a dispatching optimization algorithm was developed in this dissertation. In the development of dispatching models, two aspects need be considered: modelling of railway operation and the dispatching optimization algorithm. The former is indispensable to accurately assess the impact of disturbances, and the latter is employed to find solutions with minimal impact. In order to balance accuracy and computation complexity a multi-scale simulation model was developed in this dissertation. Dispatching optimization is a typical combinatorial optimization problem, and exhaustive search becomes impractical when there is a large set of possible dispatching solutions. To speed up the search, a widely used metaheuristic algorithm-tabu search - was adopted as the basis of the dispatching optimization algorithm. This dissertation addressed both multi-scale simulation and dispatching optimization in railway operation.

Track Data-Oriented Maintenance Intervention Limit Determination for Ballasted Light Rail Tracks through Multibody Simulations
Track Data-Oriented Maintenance Intervention Limit Determination for Ballasted Light Rail Tracks through Multibody Simulations

Author: David Camacho Alcocer

Publisher: BoD – Books on Demand

Published: 2021-07-13

Total Pages: 210

ISBN-13: 375346306X

DOWNLOAD EBOOK

Light rail trains (LRT) are an important part of public transport but due to perceived high life-cycle costs are not always considered suitable. Life cycle cost reduction might be achieved through a knowledge-based maintenance management rather than just on experience. This work develops limits of maintenance and renewal of LRT systems based on vehicle reactions to the current track quality through measured data, multibody simulations and track geometry indices. An approach based on knowledge would lead to a track condition which allows a safe, comfortable, and under an appropriate maintenance strategy, economically profitable operation.

Optimization of Schedules with Heterogeneous Train Structure in Plan-ning of Railway Lines
Optimization of Schedules with Heterogeneous Train Structure in Plan-ning of Railway Lines

Author: Hyoung June Kim

Publisher: BoD – Books on Demand

Published: 2020-06-23

Total Pages: 146

ISBN-13: 3749485062

DOWNLOAD EBOOK

One of the most important things to consider before constructing a railway is the train operating program. However, the analysis of the operating program based train schedule in the railway planning stage is carried out mainly on the basis of the intuitive experiences of the planner, and the optimization of the train schedule under various conditions is not properly considered. This study analyzes the optimization of heterogeneous train scheduling structures with minimizing the weighted scheduled waiting time and with the decision of Subsidiary Main Track (SMT) for overtaking of high-speed trains on the railway line. As a way for analyzing the Optimal Train Schedule (OTS) under constraint conditions, the genetic algorithm is used. The genetic algorithm is widely applied to various optimization and decision-making problems in engineering, natural sciences, business administration, and social sciences. The proposed method can examine train schedules for more scenarios, apply quantitative evaluation criteria, and review concrete infrastructures in comparison to the existing empirical method used in South Korea.

Investigation of Form Effect on Ballast Mechanical Behavior Based on Discrete Element Modeling
Investigation of Form Effect on Ballast Mechanical Behavior Based on Discrete Element Modeling

Author: Bo Wang

Publisher: BoD – Books on Demand

Published: 2019-08-27

Total Pages: 146

ISBN-13: 3734746663

DOWNLOAD EBOOK

As an essential component of the ballast track, the ballast layer provides functionali-ties such as drainage, load distribution, as well as strength and stability for the rail-way track. The mechanical behaviors of ballast track such as its permanent settle-ment, breakage, force propagation and void ratio are in a great extent influenced by the form distribution of ballast stones. Its reasonable design will greatly improve the mechanical behaviors, and thus prolong the maintenance cycle of ballast track, or reduce the number of ballast stones needed for construction. This dissertation focuses on proposing optimized ballast stones in the ballast aggre-gate in regard to their geometrical forms. As the first step, a ballast random form gen-erator, which is designed to generate ballast form databases with different form dis-tributions, is proposed. 15 databases are created for further usage. Afterwards, Dis-crete Element Method (DEM) based simulations are performed to investigate the mechanical behaviors of ballast aggregates. The simulation model is established based on a box test, whose result is presented firstly. Establishment and calibration process of the model are expatiated afterwards. A parameter study regarding to cru-cial modeling parameters is also performed. Using the validated parameters and the 15 generated form databases, DEM simulation models with different form distribu-tions of ballast stones in the ballast aggregate are proposed. Simulative methods to quantify the mechanical behaviors are elaborated. Based on the obtained results, the interrelation between mechanical behaviors of ballast aggregate and the form effect on mechanical behavior of the ballast aggregates are studied. The optimized ballast aggregate is proposed based on the findings stated above. The proposed optimized ballast aggregate is expected to be a reference for construc-tion of ballast track in real world. The modeling technic and the calibrated modeling parameters can be used for optimization for different railway operating programs.

Public Sector Reform
Public Sector Reform

Author: Jan-Erik Lane

Publisher: SAGE

Published: 1997-12-12

Total Pages: 322

ISBN-13: 085702616X

DOWNLOAD EBOOK

Deregulation, privatization and marketization have become the bywords for the reforms and debates surrounding the public sector. This major book is unique in its comparative analysis of the reform experience in Western and Eastern Europe, Australia, New Zealand and Canada. Leading experts identify a number of key factors to systematically explain the similarities and differences, map common problems and together reflect on the future shape of the public sector, exploring significant themes in a lively and accessible way.