| With the large-scale construction of high-speed railway,the shortage of capacity is basically relieved in China.However,because of the unbalanced distribution of passenger transportation demand on time and space,capacity utilization of converging railway sections,which lead to several railway lines,is still high,especially during peak hours.At present,signals in section are arranged with a minimum tracking interval of 3 minutes for some high-speed railway lines.As a result,headway in stations has become an important technical parameter of capacity.Analytical formulas are used to calculate headway in stations in most of existing researches.It is rough to measure headway in stations by the minimum interval between adjacent trains occupying the throat area of the station.Based on the calculation and shortening of headway in stations,capacity calculation and improvement are studied for high-speed railway.An accurate method is proposed to calculate headway in stations.A model is constructed to allocate capacity during the peak hour.And capacity improvemQnt measures are proposed based on segmental open mode of block sections and train routes.Main contents are illustrated in detail as follows.(1)The theoretical framework for capacity research is built for high-speed railway.Influence factors are divided into two categories.One is the train operation structure and the other is the interval between the tracking of adjacent trains.On this basis,the key issues of capacity research on high-speed railway are summed up in the construction of the time and space graphs for tracking process,the accurate calculation of headway in stations,and the calculation and enhancement of capacity.(2)In order to describe the time and space occupation for resources(such as track circuits)in the train operation process in sections and stations,combined with rules of operation and train routes arrangement,time and space graphs are constructed.Time and space graphs are the basis of the calculation method of headway in stations.Firstly,the train occupation unit is defined in the space dimension,and a method is given to divide occupation units in sections and stations.Specifically,the occupation unit is the track circuit in sections.The division of occupation units in stations should take track circuits,linkage turnouts and invading insulation joints into consideration.Secondly,the infrastructure occupation time in the time dimension includes routing time,reaction time,approaching time,continuous time,running time,clear time and release time.The components of infrastructure occupation time are quantized in the basis of technical standards,train running curve and speed control curve in train control system.Thirdly,areas of operation conflict are defined and distinguished.Specifically,areas of operation conflict are block sections in sections.In stations,areas of operation conflict are crossover or overlapping sections of adjacent train routes and may include the first departure block section.Finally,time and space graphs in sections and stations are constructed respectively.(3)Based on time and space graphs of tracking process for a pair of trains,an accurate method is presented to calculate headway in stations.The purpose is to provide more accurate parameters for capacity calculation.Firstly,considering the combination of the operation status,type of train route and operation direction,a general set of headway is obtained based on conflict analysis in different scenarios.Secondly,based on time and space graphs of tracking process,a calculation model of headway in stations is formulated,which minimizing the time interval of arrival time,departure time or passing through time.The calculation results of headway are accurate to ls.In the model,a station and the adjacent sections are set as scope of research.Headway for different combinations of operation speed in sections and train routes are obtained and moreover bottlenecks are identified.(4)In order to calculate capacity in busy sections during the peak hour,a model is formulated to allocate capacity and the corresponding algorithm is designed.Firstly,with time dimension accurate to ls,a directed time and space diagram is formed.Train paths in the diagram are used to describe train running process in sections,arrival,departure or passing through activity in stations.Secondly,with headway changing with the operation speed,the operation status and the station,a capacity allocation mode based on train paths is proposed.The main objective of the model is to maximize the number of trains operated.Finally,a branch and bound algorithm is designed to acquire the maximum number of trains scheduled during the peak hour,namely capacity.Column generation technology is used to solve the linear programming of each node in the branch and bound tree.(5)From the perspective of shortening headway in stations mainly,capacity improvement measures are proposed based on segmental open mode of block sections and train routes.For a block section with two and more track circuits,partition of block sections means that different track circuits are open respectively and not occupied by trains simultaneously.For a train circuit,the succeeding train can occupy it as long as the front train has released it.Partition of train routes means that it is not necessary that all the track circuits are idle when train routes are arranged in the interlocking system.For a train occupation unit in stations,the succeeding train can occupy it as long as the front train has released it.Furthermore,adjustments of time and space graphs of tracking process and the calculation model of headway are illustrated.(6)The busy section from Xuzhou East station to Bengbu South station on the Beijing-Shanghai high-speed railway line is selected as a case study.Headway in stations in Xuzhou East station,Bengbu South station and Suzhou East station is calculated.Capacity during the peak hour is allocated.The influence of partition of block sections and train routes on headway in stations and capacity is evaluated. |
PDF Full Text Request