Optimization Research On Line Passing Capacity Of Express-local Train In Urban Rail Transit

With the development of urbanization,urban rail transit lines continue to expand to the periphery,forming a city express line connecting the surrounding satellite cities and airports and other important transportation hubs.The characteristics of this kind of line are long distance,large departure interval,uneven distribution of passenger flow.And the ordinary stop operation mode can not meet the travel needs of passengers.The combined operation mode of express-local train is an important means to optimize the operation mode of this kind of lines.However,the non parallel operation chart is adopted in the mode of express-local train,and its operation organization mode and line layout are more complex.Which leads to the reduction of line carrying capacity and affects the train operation efficiency.Under this background,the paper studies the optimization of urban rail transit express-local train line capacity,optimizes the train tracking interval from the level of train operation control and realizes the optimization of line capacity.The paper introduces the concept of express-local train combination operation mode,and analyzes the characteristics of express-local train mode.In view of the fact that the domestic express-local trains mostly adopt the common line and common rail operation mode,the paper deeply analyzes the influencing factors of the line carrying capacity under the combined operation mode of express-local train from four key indicators: stop time,overtaking organization,train formation and routing plan.Finally,the calculation method of line capacity in express-local train mode is given.Which provides a theoretical basis for the follow-up study of train operation control and line carrying capacity optimization modeling.On the basis,the running process of the train is analyzed,the motion equation of the train is given through traction calculation and force analysis,and the running state of the train is simulated from the point of view of single particle and multi particle.Thus,the model of train tracking interval and the calculation method of minimum tracking interval are deduced.The optimization model of express-local train routing capacity is established with the minimum tracking interval as the optimization objective,the train running speed as the decision variable,and the safety,train parking accuracy,punctuality and passenger comfort as the constraints.Which provides the actual optimization object for the subsequent introduction of intelligent optimization algorithm.The intelligent optimization algorithm is used to solve the optimization model of the line passing capacity.In order to improve the convergence performance and global search performance of ABC algorithm,the improved global artificial colony algorithm(CGABC)based on binomial crossover operation is proposed.To verify the advanced nature of the improved algorithm,we select standard test functions Sphere and Rastrigin to test CGABC algorithm,ABC algorithm and PSO algorithm respectively.The test results show that the improved algorithm has greatly improved convergence performance,global search performance and solution accuracy.In view of the fact that the tracking interval of train running in the section is "surplus",but the tracking interval in the platform area is limited,the minimum tracking interval can be effectively shortened by reasonably adjusting the speed limit interval at the entrance platform.The optimization process of CGABC algorithm is designed to optimize the starting point of speed limit at the entrance platform,and the optimal starting point of speed limit is selected to obtain the optimized train operation curve and minimum tracking interval In order to realize the optimization of the line capacity.Taking the actual line data and train data of an urban rail transit line as a case,the MATLAB platform is used for simulation verification,and the optimized train operation curve and minimum tracking interval diagram are obtained.The results show that the optimized minimum train tracking interval is reduced from 102 s to 88 s,which meets the design standard of urban rail transit tracking interval of 90 s.The optimized train running curve is more reasonable,and the line running time is increased by 2%.Within the acceptable range,the optimized line passing capacity is increased from 26 pairs/h to 32 pairs/h,and the line carrying capacity is increased by 23.1%.In general,the objective of carrying capacity optimization is achieved,and the operation efficiency of the train is improved.