Research On Optimum Operation Scheme Of Express-Local Trains Considering The Proportion And Trainset

In recent years,the rapid urbanization has promoted the rapid growth of the population in major cities.With the outward expansion of the urban boundary,the separation of work and residence has intensified,and the urban rapid rail transit lines connecting the central and peripheral areas of the city have been accelerated to be planned and constructed.The urban express rail line has the characteristics of long line,high design speed,large average station spacing,extremely uneven passenger flow distribution in time and space,long average haul distance.So express-local trains operation mode is generally adopted.The operation of express trains will inevitably affect the rail capacity of local trains on the line.How to optimize the train proportion and train formation number of Express-Local trains under the condition of meeting the passenger flow demand of the line,so as to achieve the best operation effect,is an important issue in line planning.Based on the analysis of the characteristics,conditions and technical requirements of the express-local trains mode,this paper calculates the influence of different train proportions on the rail capacity and overtaking times under the express-local trains mode,and establishes a Logit model to analyze the route selection behavior of passengers.With the objective of minimizing the weighted sum of the total cost of passenger travel and the total cost of enterprise operation,considering the upper and lower limits of departure frequency,the safe interval of train operation,the upper and lower limits of load factor and other constraints,an optimization model of express-local trains operation scheme affected by the train proportion and the number of marshalling is established.The optimal scheme satisfying the conditions of line and passenger flow is obtained by traversing the feasible solution using genetic algorithm.The main work and achievements of this paper are as follows:(1)Based on the analysis of typical express-local trains lines such as Shanghai metro line 16,Chengdu metro line 18,New York Metro Line 7 and Tsukuba line in Japan,this paper puts forward the calculation method of passing capacity of express-local trains mode,the allocation principle of transport capacity,the adjustment method of overtaking conflict and the principle of train formation,and establishes the constraints of feasible schemes for express-local trainss.(2)The influence of different proportions of express-local trains on the rail capacity and overtaking times is calculated and analyzed.On the premise of meeting the minimum running interval of the train,the maximum departure frequency of express-local trains is calculated under the ten conditions that the proportion of express-local trains is from 1:1to 1:10,and the variation rule of the rail capacity under different proportions is obtained:with the increase of the proportion of local trains,the passing capacity of express trains will gradually decrease,and the passing capacity of local trains will gradually increase,and will begin to fluctuate within a certain range after the proportion reaches 1:4.The change trend of the total capacity of express-local trains is basically the same as that of local trains.With the increase of the proportion of local trains,the total overtaking times of the line first increase,and begin to decrease when the proportion reaches 1:3.(3)Aiming at the problem of passenger route selection in the express-local trains scheme,a Logit model of passenger route selection under the express-local trains operation mode is established.According to whether the express train stops at the station where the passenger starts and ends,the passenger travel path is divided into 8 paths.The calculation method of passenger waiting time considering the difference of passenger arrival time and the calculation method of passenger travel generalized cost are proposed.Taking the calculated total passenger travel cost as the utility value of Logit model,the path selection probability of passengers under each path is obtained,and the impact of express-local trains mode on passenger travel is analyzed.(4)Based on the passenger’s travel path selection rules and the operation principles of express-local trains.The stopping scheme of express trains,the departure frequency of express-local trains and the number of marshalling of express-local trains are taken as decision variables.The objective is to minimize the weighted sum of passenger travel cost and line operation cost.The upper and lower limits of departure frequency,the upper and lower limits of full load rate and various headway conflicts shall be taken as constraints.An optimization model of express-local trains operation scheme is established,which is coupled with the train proportion and the number of train formations,and a genetic algorithm is designed to adapt to the constraints.By dynamically changing the stop sequence,the departure frequency controlled by the train proportion and the number of express-local trains,the joint optimization of passengers and operation cost in the express-local trains scheme is realized.(5)Under the conditions of different total passenger flow and the upper limit of full load rate,the change rule of the optimized operation scheme of express-local trains is calculated and analyzed: when only the total passenger flow is increased,the scheme of increasing the number of express trains and increasing the departure frequency of local trains is more cost-effective to improve the line transport capacity;The increase of the upper limit of the full load factor can effectively reduce the operation cost of the line,but will slightly increase the travel cost of passengers.