Available online at www.sciencedirect.com ScienceDirect Transportation Research Procedia 25 (2017) 451 460 www.elsevier.com/locate/procedia World Conference on Transport Research - WCTR 2016 Shanghai. 10-15 July 2016 Study on train headway in different turning-back mode of urban mass transit station Gang Wang a,b, Huaxiang Liu b, Xiaoqing Zeng a, * a School of Transportation Engineering,Tongji University,Shanghai 201804,China b CASCO Signal Limited Company,Shanghai 200071,China Abstract The train headway is key parameter in operation organization of urban mass transit, related to service quality and operation efficiency of the transportation enterprise. This paper studies how the headway is influenced by different turning-back mode, the different calculating method for the corresponding train headway time is deduced accordingly and verified with practical example. Optimization solution for civil work design of turning-back station is given to improve operation efficiency. 2017 The Authors. Published by Elsevier B.V. Peer-review under responsibility of WORLD CONFERENCE ON TRANSPORT RESEARCH SOCIETY. Keywords: train headway, turning-back mode, urban mass transit 1. Introduction As the metro operating kilometer is increased all around the cities in China, more passenger flow is attracted due to the network operation especially in some large city. In order to transfer the large passenger flow and provide better service, high demand for train headway is required. The train headway is decided by the maximum value among train tracking interval in section, arrival interval at turning-back station, departure interval at turning-back station. The three parameters are equal in ideal condition, but if the waiting time is considered because of the operation is disturbed at turning-back station, the minimum departure interval or arrival interval will be the key factor. The turning-back headway is limited to the station layout and * Xiaoqing Zeng. Tel.: +0-8621-69583774; fax: +0-8621-65980612. E-mail address: zengxq@tongji.edu.cn 2352-1465 2017 The Authors. Published by Elsevier B.V. Peer-review under responsibility of WORLD CONFERENCE ON TRANSPORT RESEARCH SOCIETY. 10.1016/j.trpro.2017.05.425
452 Gang Wang et al. / Transportation Research Procedia 25 (2017) 451 460 turning-back mode, the length of throat area, the train running speed and signal track condition. If the I ad is defined as the turning-back headway at the turning-back station, then I ad max{ t a, t d } t a : minimum arrival interval time at turning-back station (s) t d : minimum departure interval time at turning-back station (s) 2. Calculation and analysis on station-front turning-back headway There are many types of station-front turning-back due to the layout of turning-back line, in this paper the typical type of station-front double crossover is selected to be analyzed. The train operation process at turning-back station in figure 1 (with assumption of two turning-back tracks available ). Apoint O C B side a point D platform side b E A Fig. 1. Train turning-back operation process in type of station-front double crossover The whole operation process of four train arrival and three train departure is illustrated in figure 1, i.e.: Step 1: The 1st train stops at platform side a straightly by passing D, the arrival route to side direction is set as the passengers get on or off the train, then the arrival signal is open. Step 2: After one tracking interval, the 2nd train arrives station in side direction by passing point D, stops at platform side b, then the passengers get on or off the train. Step 3: After the 2nd train stops, the turnout is switched, the departure signal is set. After the 1st train stops for given time, the driver confirms the signal to depart in side direction, then the train leaves platform side a. Step 4: After the 1st train clears the axle counts (or track circuit) of station-front crossover, the turnout is switched, the arrival signal is opened. The 3rd train driver confirms the signal, then running to point D, then stops at platform a in straight direction. Step 5: After the 3rd train stops, the turnout is switched, the departure signal is set. After the 2nd train stops for given time, the driver confirms the signal to depart in straight direction, then the train leaves platform side b. Step 6: After the 2nd train clears the axle counts (or track circuit) of station-front crossover, the turnout is switched, the arrival signal is opened. The 4th train driver confirms the signal, running to point D, then stops at platform b in side direction. Hereafter a cycle is made back to step 3. The cycle flow chart of the train turning-back operation is illustrated in figure 2.
Gang Wang et al. / Transportation Research Procedia 25 (2017) 451 460 453 Fig. 2. Train turning-back operation process flow chart in type of station-front double crossover In actual operation, the time for train straight direction arrival is different from the side direction arrival, and the time for train straight direction departure is different from the side direction departure, but no big difference between them. To be clear, same value is taken in this paper. Then in this turning-back type, the train turning-back headway is illustrated as figure 3.
454 Gang Wang et al. / Transportation Research Procedia 25 (2017) 451 460 t star Point A of departure switch point t leave t leave t leave t operate+ t confir Station platform t stop Point D of up line t t t operate+ t confi t t arrive tenter t enter Fig. 3. Schematic diagram for train turning-back headway in type of station-front double crossover turning-back To ensure safe, the above need meet the following condition: t operation t confirm It is observed directly from above figure, the value of arrival interval is equal to the value of departure interval in this type of turning-back mode, which could be described as following: t t t t t tenter depart arrival leave operation From the previous analysis, the factors that influence the train turning-back interval could be found as following: I. The running time that 2 nd train arrives station in side direction passing by station-front crossover. II. The running time that 1 st train clears axle count (track circuit) point A, passing by station-front crossover from platform a. III. The time of 1 st train departure route set and the time of ATP/ATO action. IV. The time of 3 rd train arrival route set and the time of ATP/ATO action. confirm 3. Calculation and analysis on station-end turning-back headway There are many types on station-end turning-back due to the layout of turning-back line, in this paper the typical type of station-end crossover is selected to be analyzed., 3.1. Calculation on minimum arrival interval The arrival operation process of the train at turning-back station is as figure 3: the previous train arrives at platform a, the passengers get off and at same time the turning-back route is pre-set, and the turning-back signal is opened after all passengers get off; The previous train driver confirms the signal; The previous train runs to axle counter (track circuit) point A, then the entering station signal is open when the tail of train passes point A. The subsequent train driver confirms the signal; The subsequent train runs to station by passing point A and stop at platform a.
Gang Wang et al. / Transportation Research Procedia 25 (2017) 451 460 455 point A point O point B platform side a side b point D Fig. 4. Train arrival operation process in type of station-end double crossover The whole operation process is described as figure 5.
456 Gang Wang et al. / Transportation Research Procedia 25 (2017) 451 460 Fig. 5. Train arrival operation process in type of station-end double crossover From the above analysis, the calculation equation of the minimum of arrival interval is: t arrival In above formula: stop 1 confirm leave operation 2 confirm enter t stop 1 t confirm t leave t operate 2 t confirm t enter : stopping time of 1 st train stopping at platform a (s); : time of 1 st train confirm signal (s); : time of 1 st train leaving station axle counts (s); : operation time for 1 st train stopping at platform a (s); : time of 2 nd train confirm signal (s); : time of 2 nd train running from point D to station (s); To ensure safe and keep the train always running with normal speed in green light, the distance between the position of subsequent train (point D) and entering station signal light should be ensured to let the train stop before entering station signal light. In this type of turning-back, the minimum arrival interval is described as figure 6. Point A of station track circuit t leave station platform a t ente t stop+ t 2 conf t stop+ t 2 conf point D of station up line t arrive previous train subsequent train Fig. 6. Schematic diagram for train arrival interval in type of station-end double crossover From the previous analysis, the factors that influence the train arrival interval are: I. The stopping time of previous train. II. The time of previous train tail running from platform a to point A of station block section. III. The time of subsequent train running from point D to platform a. IV. The time of route is set and ATP/ATO action. V. The time to judge whether the route is set and to confirm the route signal.
Gang Wang et al. / Transportation Research Procedia 25 (2017) 451 460 457 3.2. Calculation on minimum departure interval The departure operation process of train at turning-back station is as figure 7: point point point B platform side a side b point D Fig. 7. Train departure operation process in type of station-end double crossover The whole operation process is described as following: the previous train leaves point A of station block section; the route leaving turning-back track is set and the signal is open; the driver confirms the signal and the train runs to platform b and stops from the end of turning-back track; After all passengers get on in given time, the departure signal is open; the driver confirms signal. The whole operation process is described as figure 8: 1 st train leaves point A of station block section The route to platform b passing by turningback track from point B is set ATP/ATO acts 1 st train confirms signal N Y 2 nd train runs to platform b passing by turning-back track from point B 2 nd train stops and at the same time the route from station to point A of station block section is set ATP/ATO acts 2 nd train confirms signal N Y Fig. 8. Train departure operation process in type of station-end double crossover
458 Gang Wang et al. / Transportation Research Procedia 25 (2017) 451 460 The train departure interval is described as figure 9: point A of down line station block section t depart t operate+ t 1 confirm t start station platform b point C of up main line t stop+ t 2 confirm previous train subsequent train t outgoing Fig. 9. Schematic diagram for train departure interval in type of station-end double crossover From the previous analysis, the factors that influence the train departure interval are: I. The running time that previous train leaves point A of station block section from platform b. II. The running time that subsequent train arrives at platform b passing by turning-back track from B. III. The stopping time of subsequent train in platform b. IV. The time that the route is set and the time that ATP/ATO acts. V. The time for driver to judge whether the route is set and to confirm the route signal. 4. Simulation and Result Based on above analysis, we take the station Pingguoyuan of Beijing Line 1 as an example to make simulation. The platform length of this station is 118m, the length of train is 117.17m, the average brake speed is 0.88m/s 2, the acceleration is 1m/s 2, the distance for train to enter station by down line is 437m, the distance for train to leave station by up line is 561m. After measurement, the arrival interval is 113 second in peek time, 123 second in no-peak time, in turning-back of station-front double crossover. Considering the driver reaction time of the previous and subsequent train, the total turning-back interval is 128 second in peak time, 118 second in no-peak time. With the same way, the simulation result is got for turning-back type of station-front single crossover, stationfront double crossover and station-end end line. The train turning-back headway is got in several type as table 1. Table 1. Train turning-back interval in different type Type of turning-back Station-front Single crossover Station-front Double crossover Station-end Double crossover Time (s) 127 113 118 117 Station-end End line
Gang Wang et al. / Transportation Research Procedia 25 (2017) 451 460 459 From above table, we could see the difference is very small between station-end double crossover turning-back and station-end end line turning-back, but the difference is a little big between station-front single crossover turningback and station-front double crossover turning-back. It is mainly because the stopping time is made full use of in type of station-front crossover turning-back, and in practical the operation of single crossover turning-back is easier than the operation of double crossover turning-back. The table 2 is the comparison of several turning-back type. Table 2. Comparision of Station-front Single crossover turning-back Station-front Double crossover turning-back Turning-back headway large A little Little Running time short A little Short Long Line length Short Short Long Operation difficulty easy Difficult Easy Station-end Turning-back Based on above analysis, we could find the main factors to influence the train turning-back interval both in station-front turning-back and station-end turning-back are: the running time that the departure train leaves station block section and the stopping time of the train in station. The different factors to influence the train turning-back interval in different situation are: In station-front turning-back: the time to set entering station route for entering station train and the time for ATP/ATO action; the running time for train from entering station signal light to arrival station track. In station-end turning-back: the time to set dispatch route for turning-back train and the time for ATP/ATO action; the running time for train from turning-back track to departure station track. 5. Conclusion Considering above various factors, to short train turning-back headway, the following suggestion is given: Shorten the time to enter the station and to leave the station. To reach this target, two main ways could be taken including improving the speed of entering station and leaving station,and reducing the train running distance. By improving the train acceleration to shorten the train running time, by taking large-size turnout to improve the train speed passing by side direction, by shortening the length of speed zone to make turnout area close to platform to reduce the train running distance, by taking moving block or automatic driving to reduce train running distance to shorten running time. Build the side platform. By this way, the departure platform will be type of one island on side to shorten the total time for passengers getting on or off, to accelerate the train turning-back turnover. References Junfang, L., Xiaomei, F., 2009. Turning-back Capacity Calculation of Urban Mass Transit Station, Railway transport and economy Vol 31(5), 50-53. Guobao,Z., Tao, Y., 2006, A Study on the Turn-back Capacity of Trains on Urban Rail Transit, Urban Rapid Rail Transit, Vol 19(4), 55-58. Jingfeng,W., Lun H.,2008, Analysis on Station-front Turning-back Capacity, Journal of Shijiazhuang Railway Institute (Natural Science), Vol 21(1), 26-30 Hongyuan,D., 2002, The Analysis and Comparison on Station-end Turn-back Mode, Rail Communication and Signal Design, 2002(4), 8-12. Tao,L., 2008, Turning-back Capacity and impact factors of Urban Mass Transit, Railway Signalling Communication, Vol 144(12), 17-20. Haidong,L., Baohua,M., Tianjian,H., Yong,D., Xuan,W., 2005, Study on tracking operation between trains of different block and simulation system, Journal of the China Railway Society, Vol 27(2), 120-125. Xiaolong,Z., 2006, Theoretical Analysis and Computer Simulation on Train Line Carrying Capacity on Urban Rail Transit Songliang,L.,2002, Analysis of Advantage and Disadvantage and Turn-back Capacity Calculation in two turn-back type of Terminal Station, Metro and Light Rail Transit, Vol 2002(4), 32-33.
460 Gang Wang et al. / Transportation Research Procedia 25 (2017) 451 460 Jiubiao,L., 2008, Analysis on Station-front Turning-back Capacity for Urban Rail Transit, Urban Rapid Rail Transit, Vol 21(5), 27-30. Juan,J., Mei,Y., Changlin,W., 2005, Research on Carrying Capacity for Subway Track Based on Principle of Movable Block, Railway Computer Application, Vol 17(6), 7-10 Chunyu,L., Wen,D., Xiaobo,Z., 2009, Analysis of Reentry Models on the Intermediate Turn-back station of Urban Rail Transit, Urban Rapid Rail Transit, Vol 22(1), 44-48 Fan,J., 1995, A Study on Simulation Calculation method of Metro Train Turn-back Capacity, Metro and Light Rail Transit, 1995(1), 32-35 Runzhao,L., 2010, Optimization Research on Turn-back Ability of Double-crossover returned Station of Urban Rail Transit.