Xuelei Meng

Train Timetable Optimizing and Rescheduling Based on Improved Particle Swarm Algorithm

A train timetable is the key to organizing railway traffic and determining the inbound and outbound times of trains. The goals for optimizing a timetable are to improve stability (the most important index) and to offer more feasibility for train rescheduling when disruptions occur, with high railway capacity utilization as a prerequisite. Train rescheduling must ensure traffic order and efficiency and adjusts train movements to be consistent with the schedule as much as possible. The two problems have the same basic solution method: to adjust the inbound and outbound times of trains at stations. Timetable stability is defined by focusing on the buffer time distribution for trains in sections and at stations. A timetable optimizing model that takes stability as the optimizing goal and a rescheduling model with minimal summary time as the destination are presented. The particle swarm algorithm is improved and is applied in problem solving as a time-adjusting tool. The algorithm is illustrated by two examples from the Guangzhou-to-Shenzhen section in China. The improved particle swarm algorithm is proved to have real-time adjusting ability, showing its high convergent speed. It is concluded that the algorithm has great global searching ability. The described new method can be embedded in the decision support tool for timetable designers and train dispatchers.

Controllability of Train Service Network

Train service network is a network form of train service plan. The controllability of the train service plan determines the recovery possibility of the train service plan in emergencies. We first build the small-world model for train service network and analyze the scale-free character of it. Then based on the linear network controllability theory, we discuss the LB model adaptability in train service network controllability analysis. The LB model is improved and we construct the train service network and define the connotation of the driver nodes based on the immune propagation and cascading failure in the train service network. An algorithm to search for the driver nodes, turning the train service network into a bipartite graph, is proposed and applied in the train service network. We analyze the controllability of the train service network of China with the method and the results of the computing case prove the feasibility of it.

Study on Train Operation Adjustment Based on Hybrid Convergent Particle Swarm Optimization

Train operation adjustment is an important part of the railway dispatch work, which is the core work to assure the transportation order and efficiency. The essence of the adjustment is to adjust the train to run according to the planned schedule. In this paper, a train operation adjustment model is built and the hybrid convergent particle swarm optimization is employed to solve the optimizing problem. It not only satisfies the constraints of train operation adjustment, bt also has the real-time adjusting ability. Computing results are changed into a train operation adjustment plan. It is concluded that the algorithm has excellent performance, compared with the basic swarm algorithm. The train operation adjustment plan is practical and efficient.

Networked Timetable Stability Improvement Based on a Bilevel Optimization Programming Model

Train timetable stability is the possibility to recover the status of the trains to serve as arranged according to the original timetable when the trains are disturbed. To improve the train timetable stability from the network perspective, the bilevel programming model is constructed, in which the upper level programming is to optimize the timetable stability on the network level and the lower is to improve the timetable stability on the dispatching railway segments. Timetable stability on the network level is defined with the variances of the utilization coefficients of the section capacity and station capacity. Weights of stations and sections are decided by the capacity index number and the degrees. The lower level programming focuses on the buffer time distribution plan of the trains operating on the sections and stations, taking the operating rules of the trains as constraints. A novel particle swarm algorithm is proposed and designed for the bilevel programming model. The computing case proves the feasibility of the model and the efficiency of the algorithm. The method outlined in this paper can be embedded in the networked train operation dispatching system.

Train re-scheduling based on an improved fuzzy linear programming model

Train re-scheduling remains a long-standing challenge in railway operation. To design high-quality timetable in fuzzy environment, this chapter studies train re-scheduling problem under the fuzzy environment, in which the fuzzy coefficients of the constraint resources have the fuzzy boundaries. Based on the improved fuzzy linear programming, the train re-scheduling model is constructed. Aiming at dealing with the fuzzy characteristics of the constraint coefficients value range boundaries, the description method of this kind of objective function is proposed and the solving approach is presented. The model has more adaptability to model a common train re-scheduling problem, in which some resources of the constraints are uncertain and have the characteristics of fuzziness and the boundaries of the resources are fuzzy. Two numerical examples are carried out and it shows that the model proposed in this chapter can describe the train re-scheduling problem precisely, dealing with the fuzzy boundaries of the fuzzy coefficients of the constraint resources. The algorithm present is suitable to solve the problem. The approach proposed in this chapter can be a reference for developers of railway dispatching system.

Fuzzy optimization model based tolerance approach to timetable rescheduling for high speed railway in China

A fuzzy optimization model based tolerance approach is proposed to handle timetable rescheduling in high speed railway during speed restriction period. As the limited speed and headway time are not crisp figures in practice especially when some natural hazards happen or some equipment failure, tolerance approach is introduced with the fuzzy membership functions of the original objective and soft constraints to find an new optimal objective with little slack of constraints. The original objective is treated in the same manner as the soft constraints, so the model is symmetric. The proposed fuzzy rescheduling model is simulated on the busiest part of a high speed railway line in China. The entire case study shows the significance of fuzzy optimization in case of speed restriction. The results shed light on how we could choose a better limited speed and headway time, so that the number of seriously impacted trains can be reduce greatly with little cost and risk.

Notice of Retraction The fuzzy comprehensive evaluation of the highway emergency plan based on G1 method

The huge economic loss and serious social problems are brought to the country by the frequent happening of highway emergency. Therefore, how to avoid and reduce its impact is particularly important. Then, the emergency plan is an important part of the emergency rescue system, and the effective evaluation should be made for the highway emergency plan, which is of great importance to make fast and effective emergency response and reduce the impact of the emergency. In this paper, according to the characteristics of highway emergency plan and the related research, the evaluation index system is firstly established, then, G1 method is used in the calculation of the index weights, and thus the fuzzy evaluation method is cited to make a comprehensive evaluation on the emergency plan, which make subjective evaluation objective, so the accuracy of the evaluation have been improved. Finally an example is given to verify the proposed method, which provides the effective assessment to the highway emergency for reference.

Complex characteristic analysis of passenger train flow network

Train flow network is a complex network. The small-world and scale-free characteristics are analyzed. A computing example is carried out to show how to calculate the average path length and the cluster coefficient. The characteristics of the network built with all the trains of a national service plan are analyzed by the same method. It proves that the train flow network is a typical complex network and it is robust to the random disturbance while vulnerable to the deliberate attack. The analysis of the results can give valuable supporting information for the railway operators.

Hybrid Timed Event Graph Model for Networked Train Operation Simulation and Timetable Stability Optimization

To improve the possibility of recovering the status that the trains are running as arranged by the timetable, a hybrid timed event graph model is presented. We analyze the discrete and continuous events, determining two kinds of discrete positions, two kinds of discrete transfers, a kind of continuous position, and a kind of continuous transfer for the hybrid timed graph model. We construct the hybrid timed event graph model for simulating train operation process, distributing trains on the different paths on the railway network. Then, the networked timetable stability is defined. Based on the definition, we give the method to optimize the networked timetable stability, repeating the simulation, till the satisfying results are attained. The computing case proves the feasibility of the model and the efficiency of the algorithm. The method presented in this paper can be embedded in the networked train operation dispatching system.

Open integration architecture of railway safety comprehensive monitor system

This paper analyses the complexity of building railway safety comprehensive monitor system. An Open Integration Architecture of Railway Safety Comprehensive Monitor System (OIA/RSCMS) is proposed on the basis of study on this system building characteristic and present integration architecture. Qinghai-Tibet railway safety comprehensive monitor system is put forward to be built under the guidance of the architecture.