Theory And Method Of Cyclic Train Connection Plan For High Speed Railway

With the formation of large scale high speed railway network and the increase of transport capacity in China, it is an opportunity to improve the passengers’service quality and market competitiveness for Chinese Railway Company. At present, there is a large number of transfer ODs due to the large scale of China high speed railway network, of which the percentage is about 75.8%～90.2%. In order to increase the direct service level, China Railway Company operated a lot of trains whose operation distance is very long, and had many train ODs and dwell patterns.The service among big cities with medium and short distance has high frequency but lack of regularity. However, the service between two big cities with long distance and between two small or medium-sized cities is with low frequency, even that passengers have to transfer in journey. How to improve the transfer efficiency becomes a key and complicated issue in railway timetable design. Due to the advantages of cyclic timetable which is very popular in European railways, it is suggested for us to adopt cyclic timetable to solve the networked transfer issue in China.European and Japanese high speed railways adopt the cyclic timetable, and have a large number of train connections to improve transfer passengers’service. After many years’market optimization, most of passenger ODs could have high frequency services composed by direct services and connection services, so that passengers could depart at any time which is convenient for passengers to choose trains.Because of short operation time, Chinese high-speed railway has not yet adopted cyclic timetable and hasn’t form clear train connections, which is different from European railways. The current service of train connections in China is less than that in European railways in transfer distance, transfer time, service frequency and regularity etc. How to design train connections become a key problem for the application of cyclic timetable in Chinese large scale high speed railway network.Train connection design is a collaborative optimization of train plan and timetable. Train plan controls the size and top-level service quality of transfer passengers by designing trains ODs, their train stops and max transfer times etc. At timetabling, the arrival and departure time of connection trains are formulated to make sure transfers having suitable transfer time. Train connection plan is consisted by some elements of train plan and timetabling, which define the connection relationship and interval time between feeder trains and connecting trains. This paper focuses on theory and method of cyclic train connection plan for Chinese high speed railway. The main research contents include the following aspects:(1)The transfer passenger demand analysis of Chinese high speed railwayFrom the perspective of railway enterprise and passenger respectively, the paper analyzes the influence factors of passengers’choice between direct service and transfer service. Then, a classification node system is established based on the economy, passenger flow, administrative level and railway infrastructures etc. The transfer ODs’ scale and components of transfer passengers are estimated based on the classification node system.(2) The definition of train connection plan and the process of generatingThe basic definition, properties and elements of train connection plan are summed up. Based on the timetable of European railway, the characteristic of European railway’s network structure, the organization of transfer passengers and the pattern of train connection are analyzed. According to the situation of China high speed railway, the author puts forward a process of generating train connection for China high speed railway so that the train connection plan could be confirmed and optimized gradually.(3) Optimizing the train connection constrains for a regular timetableOne of contents in this paper is to study the process and key technologies of train connection generation method. First, the study focuses on the generation strategy of train connection pool and train connection constraint generation process for timetabling. Second, the coupling property of train connection is analyzed which leads to the problem of connection conflicts. Third, the criterion to find connection conflict is put forward, and tear cycle method is used to avoid train connection conflict. A train connection generation model called Potential Train Connections Model is provided after revealing possible train connection conflicts.(4) A new cyclic timetabling model for potential connections.Cycle Periodicity Formulation (CPF) is a traditional model for cyclic Timetabling, which has clear connection constraints. Chinese high-speed railway hasn’t adopted a periodic timetable, and the train connections are not formed specifically. CPF model can only base on the potential connections, which lead to the variation of constraint graph describing the CPF model and lack guarantee for transfer passages’connection service quality. In response to these problems, this paper improve the CPF model in terms of decision variables, objective function, constraints, and an new cyclic timetable model called Potential Connections & Cyclic Timetable Model is provided to adapt the characteristic of Chinese high speed railway. This paper proposes a new integer cycle base called classified integer cycle base to avoid the variation of constraint graph, and introduces a notation called "double train connection" to guarantee the connection service quality of two transfer passengers.(5) Model for cyclic timetable optimization with flexible passenger connectionsFor the decrease of service quality in two stage program to generate train connection, we put forward an optimized idea which is the feedback from the cyclic timetable to train connections. Based on this idea, we propose a bi-level programming model whose upper level model is a connection demand model which decides the train connections with the objectives of minimal number of connections and maximal service passenger ODs. The lower level model is a Cycle Periodicity Formulation (CPF) which optimizes the timetable with the objective of minimal of total passenger travel time. An iterative algorithm is applied by use of the greedy algorithm for upper model and branch and bound algorithm for lower level model.(6)Case studyAt the background of Chinese high speed railway network at 2016, a case study is verified the effectiveness of the proposed three models, which were solved by mixed programming with VS2010 and Cplex 12.3. Based on a given periodic train line plan, we get an optimized train connection plan and cyclic railway timetable, therefor the proposed three models are feasible.This paper has formed a theory and method for generating cyclic train connection plan for high speed railway. A periodic train connection plan and a cyclic timetable servicing big cities are designed for China high speed railway. The theory and method are of great significance for designing cyclic timetable, improving the service level of transfer passengers, providing support to enhance market competitiveness, attracting more passengers for China high speed railway.