Optimization On The Proportion Of Express/Local Train For Suburban Lines Of Urban Rail Transit

With the advancement of urbanization in China,many cities,especially the first tier cities,have established satellite towns in the suburbs.In order to meet passenger travel needs to and from downtown and suburbs,suburban rail transit lines came into being.Compared with ordinary urban lines,the passenger flow distribution of suburban lines has its unique characteristics.Because most of the passengers on the suburban lines are commuters and students,the passenger flow is obviously uneven in time and space.Based on the needs of different types of passengers,the express/local mode can not only meet the needs of longdistance passengers,but also meet the needs of short-distance passengers.But the proportion of express/local train must be determined according to the passenger flow in different periods.The study on the optimization of the proportion of express/local train is conducive to improving the service level of the line,reducing the operating cost and avoiding the waste of the line capacity.Therefore,based on the above purpose,this paper studies the proportion of express/local train running on urban rail suburban linesFirstly,the paper discusses the suburban line type of rail transit and the express/local mode,points out that the most important factor affecting the proportion of express/local train is the characteristics of passenger flow,and summarizes three indicators to measure the unbalanced distribution of passenger flow in time and space: direction imbalance coefficient,section imbalance coefficient and time imbalance coefficient.At the same time,based on the actual data of Shanghai rail transit line 16,the spatial and temporal distribution of passenger flow on suburban lines is analyzed comprehensively.From the calculation results,it can be seen that the imbalance degree of time-sharing passenger flow in the whole day of line 16 is large,and the tidal phenomenon of passenger flow is relatively prominent.When making the operation scheme,especially determining the proportion of express and local trains,different situations must be discussed in different directions and periods.Secondly,the paper uses two methods of ordered sample clustering and K-means clustering to divide the whole day based on the passenger flow data.When clustering the continuous time series samples with passenger flow as attribute,the first choice is the ordered sample clustering method,which is solved by Fisher optimal segmentation method.Meanwhile,the improved k-means algorithm is used for clustering,and the different results under the two methods are compared.As a result,the division of up and down direction periods of Shanghai metro line 16 is determined based on the actual situation.Then,based on the matching of transportation capacity and passenger flow,the optimization model of express/local train proportion is established.Based on the actual operating situations,this paper puts forward that the express/local train should run under different proportion according to the up and down directions and different time periods,and then makes relevant assumptions and parameter settings according to the problem description.At the same time,the model is solved under 3 constraint conditions,such as the full load proportion of the train and the time interval of train tracking.Considering the benefits of passengers and enterprises,three evaluation indexes are given,including the total waiting time of passengers,the number of departures and stops in the whole day.Last,this paper briefly introduces the general situation and operating status of Shanghai rail transit line 16,and takes its downward direction as an example to optimize the proportion of express/local train.The optimization results are as follows: 6:00-7:00(1:1):4 express and 4 local trains per hour,7:00-9:00(1:1),8 express and 8 local trains per hour,9:00-23:00(1:3),2 fast trains and 6 local trains per hour.And compared with the current scheme,the number of departures,train stops and total waiting time are reduced.The research results show that the optimized proportion of express/local train is adaptable to the passenger flow demand of the line,achieving the purpose of improving the line service level and reducing the vehicle operating cost.It is found that the proportion of express/local train is related to the train interval.Because small marshalling express trains and large marshalling of local trains are currently used in Shanghai metro line 16,it is necessary to shorten the departure interval and increase express trains to match the passenger flow.If the current departure interval is continuing,the number of large marshalling trains needs to be increased to avoid the shortage of transportation capacity.