Frontiers in Business, Economics and Management ISSN: 2766-824X | Vol. 3, No. 3, 2022 103 Research on The Combined Operation Mode of Express‐ local Train in Urban Railways -- Taking Wenzhou Rail Transit Line S1 as an Example Yujun Pan*, Lihong Yang School of Ruian, Wenzhou Polytechnic, Wenzhou, 325000, China Abstract: The applicability of the combined operation mode of express-local train trains is analyzed. The express-local train without overrun scheme and the express train overrun scheme are studied. The influence of different express-local train schemes on the line capacity is analyzed. The setting method of express train non-stop and express train overrun station is determined. Finally, taking the Wenzhou Rail Transit Line S1 as an example, combined with the actual passenger flow data and travel plan data, the express-local train operation plans under different express and local train ratios are determined. It provides a reference for enterprises to operate express-local train trains. Keywords: Express-local Train, Urban Railways. 1. Introduction The express-local train mode refers to an operation organization mode in which two types of trains that stop at the station and stop at the cross-station are combined with a certain operating ratio. It can better meet the requirements of long-distance passengers to travel quickly, and thus, the fast and slow mode can better adapt to the different travel needs of different passengers. Due to the different travel speeds, trains that stop at stations are called local trains, and trains that stop across stations are called express trains. The express-local train mode can meet differentiated services: it not only meets the needs of station coverage along the line, but also meets the needs of long- distance travel passengers to arrive quickly. The passenger flow in the express-local train mode is uneven in time and space, and the line mileage and the average station distance for express and local trains are usually long. Practical experience shows that the mileage of existing express-local trains at home and abroad is over 45 kilometers, and the average distance between stations is usually 3 to 6 kilometers. 2. The Basic Theory of Express-Local Train Mode 2.1. Applicable The implementation of the express-local train plan first needs to analyze the passenger flow. Only when the spatial and temporal distribution characteristics of passenger flow are suitable for express-local trains can the scheme give full play to its advantages and avoid disadvantages, so as to better serve passengers with different travel needs. 2.1.1. Time Distribution Characteristics of Passenger Flow Different time distribution characteristics of passenger flow will have different impacts on the express-local train scheme. If the passenger flow of certain ODs in a certain time period is extremely large, it can be considered to operate more corresponding express trains in this time period to meet the needs of passengers travel needs. If the passenger flow is evenly distributed in time and there is no obvious peak, it may be considered to implement the express-local train mode at all times throughout the day. Therefore, it is necessary to analyze the time distribution characteristics of the passenger flow of the line in detail when formulating the express-local train plan, and then determine the running time period of the express- local trains on the line or adjust the running ratio of the express-local trains based on this. 2.1.2. Spatial Distribution Characteristics of Passenger Flow The passenger flow of line services with different positioning usually also has different spatial distribution characteristics. When considering the express-local train scheme, it is necessary to combine the line positioning to analyze the spatial distribution characteristics of passenger flow, such as passenger flow cross-section and passenger flow direction. If the passenger flow of each station is similar, the express-local train plan is not suitable. If there are obvious large and small passenger flow stations on the similar line, it is suitable to run express trains between the large passenger flow stations to improve the passenger flow travel efficiency of the large passenger flow stations, and then use the local train to provide travel services for the small station passenger flow with a small number. In the direction of passenger flow, because the passenger flow itself has a direction, the upstream and downstream passenger flows are often different in the same time period, or even quite different. Generally, it can be expressed by the unbalanced coefficient of passenger flow γ.  up downmax max up down max max max , + q q q q   （ ）/2 Where up maxq is the maximum cross-section passenger flow of the upward [person/h], and down maxq is the maximum cross-section passenger flow of the downward [person/h]. γ>1, and the larger the value is, the driving plan needs to be formulated separately for the up and down. 104 2.2. The Express-local Train Plan 2.2.1. No Overrun Express-local Train Plan No overrun express-local train refer to express trains that do not stop and pass at some stations with a small passenger and drop capacity. Since there is no overtaking behavior, the line is generally two-lane, and the express train and the local train share the line, which has little impact on the passing capacity of the line. During the operation of this scheme, it is necessary to ensure that the tracking interval between the trains in the section and the station is less than the minimum tracking interval. The scheme of express-local trains without overtaking is shown in Figure 1. Figure 1. The schematic diagram of no-overtaking express-local train scheme Since some stations of the backward express train do not stop, the travel speed is increased, so that the tracking interval between the backward express train and the forward slow train is reduced. Since the forward local train is not overtaken, in order to ensure the safe operation of the train, the arrival interval of the front and rear trains at the terminal station needs to be guaranteed at least is the minimum tracking interval. 2.2.2. Express Train Overtaking Plan The express train overtaking and local train scheme requires the line to have the train overtaking capability. According to the position of the express train overtaking the local train, it can be divided into two forms: section overtaking and station overtaking. Section crossing requires the crossing section line to be more than two lines. If the station overruns, the overrunning station needs to have the ability to overrun. Generally, it can be set up as a station with two island platforms and four traffic lines. However, when the station overruns, the local train needs to wait for the express train to overrun to prolong the stop time of the local train. Therefore, the station overrun has a greater impact on the local train and the capacity of the line. The schematic diagram of the station crossing is shown in Figure 2. Figure 2. The schematic diagram of express train overtake local train 2.3. Influence of Express-local Train Scheme on Line Capacity The impact of express trains overtaking local trains at stations is determined by various tracking interval constraints. The minimum tracking interval is the minimum time interval during which the preceding and following trains run according to the operation plan without affecting each other. Urban rail transit lines are generally double-track. Therefore, for the lines laid out by two lines in the interval, the minimum driving interval of urban rail transit can be expressed as the sum of the maximum stopping time and the minimum tracking interval. The biggest influencing factor of the line's passing capacity is the line's minimum driving interval. With the minimum tracking interval of 90s, the research and discussion are carried out on different stop times and the ratio of express-local trains. Referring to the regulations of subway design code (GB50157-2013), take the minimum train station arrival interval Ida=90s, when the stop time tz=30s, the minimum travel interval at this time is Iaa=Idd=Ida+tz=120s, corresponding to the traffic density is 30 columns/h. Iaa and Idd are the sum of the minimum tracking interval and stopping time. The values of various tracking intervals used in the other combined optimization models are shown in Table 1. 105 Table 1. Various tracking interval values Parameter Name Meaning Value Ida At the same station, the minimum departure time between the departure of the preceding vehicle and the arrival of the following vehicle. 90s Idt At the same station, the minimum time between the departure of the preceding car and the passing of the following car without stopping. 150s Ita At the same station, the minimum pass-to-arrival interval for the preceding vehicle to pass without stopping and the following vehicle to arrive. 120s Iat When overtaking occurs, the minimum time between arrivals of the preceding vehicle and overtaking of the rear vehicle. 60s Itd When overtaking occurs, the minimum passing interval for the preceding vehicle to overtake and the rear vehicle to depart. 90s When running express-local trains, the formula for calculating the capacity of urban rail transit lines is as follows. 1 max 2 3600 * ( 1) ' f n T f   1 1 m 2 2 ' ( 2) * I ( 1) *in f f T tz f f     Where 1f is indicates the frequency of local departures [columns/h], and 2f is indicates the frequency of express departures [columns/h], and tz is stop time[s]. (a)The number of express trains :the number of slow trains=1:1 (b) The number of express trains :the number of slow trains=1:2 Figure 3. Rail capacity of express-local train Table 2 shows the calculation results of the line passing capacity under the conditions of different stop times of local trains at overpassing stations and different ratios of express- local trains. Table 2. Rail capacity under different station dwell time and departure ratio of express-local train 1 2:f f tz 1:1 2:1 3:1 4:1 30 26 27 28 28 35 26 27 27 27 40 26 27 27 27 45 26 26 26 26 50 26 26 26 26 55 26 26 25 25 60 26 25 25 25 2.4. Setting of Non-stop and Over-travel Stops for Express Trains 2.4.1. Express Train Non-stop Station By reviewing literature and referring to actual operating experience, it is concluded that express train stops should be set up at stations with an average daily passenger drop of more than 100,000 passengers, and express trains at stations with an average daily passenger drop of less than 50,000 passengers may not have a stop. The above experience can be used for verification and comparison after generating the scheme. The optimal non-stop express train scheme for different lines should be calculated according to the passenger flow distribution of different lines. 2.4.2. The Overpass Station Regarding the setting of overpassing stations, firstly, it should be judged whether the express train needs to overtake the local train at a certain station in front of the terminal, and then the position of the overpassing station should be judged 106 according to the tracking interval between express trains and local trains at each station. According to whether the arrival interval of the following express train and the preceding local train at the terminal satisfies the minimum tracking interval, it is determined whether the express train needs to overtake the local train. When the tracking interval between the following express train and the preceding local train at the terminal is less than the minimum arrival interval, that is T’< Imin. At this time, the express train needs to cross a certain station before the terminal and proceed to the local train. The selection of the overpass station is determined according to the tracking interval, and the overpass situation is shown in Figure 4. (a) A case of express train overtaking (b) Another case of express overtaking Figure 4. Different situations of express train overtaking A case of overtaking express trains means that the tracking interval between the express train and the preceding local train at station j satisfies the minimum train departure interval Idt, but the tracking interval at station j+1 does not meet the train minimum arrival interval Imin. Station j traverses the slow train. Another situation of express train overtaking means that the tracking interval between the express train and the preceding local train at station j satisfies the minimum train arrival interval Iat, but does not meet the train minimum departure interval Idt. In this case, the express train needs to overrun the preceding local train at station j. An overrun occurs when either of the two conditions is satisfied. And both situations occur when the express train does not stop. The location of the over-travel station can be generated after determining the non-stop plan for express trains, which has nothing to do with the distribution of passenger flow. 3. Take Wenzhou Rail Transit Line S1 as an Example 3.1. The Wenzhou Rail Transit Line S1 The Wenzhou Rail Transit Line S1 is the first urban rail transit line built and operated in Wenzhou. The west section of the first phase of the project (Tongling to Olympic Center Station) was opened on January 23, 2019, and the east section (Olympic Center Station to Shuang’Ou Avenue ) was opened on September 28, 2019. The Wenzhou Rail Transit Line S1 generally runs east-west, starting from Tongling in the west and ending at Shuang’Ou Avenue in the east. It has a total length of 53.5 kilometers, and the length of the line meets the requirements for running express-local trains. The line has 18 stations, including Tongling, Panqiao, South Railway Station, Xinqiao, Dezheng, Longxia Road, Huimin Road, Sanyang Wetland, Longteng Road, Science and KeJiCheng, Yao Xi, Olympic Center, Yongzhong, Airport, Lingkun, OuJiangKou, Ouhua, and Shuang’Ou Avenue. It adopts 4-car marshalling D-type trains, which are marshalled for municipal railways. Figure 5. The Schematic diagram of Wenzhou Rail Transit Line S1 107 3.2. Passenger Flow Characteristics and Setting of Over-travel Stops According to statistics, the full-day time-sharing passenger flow data and cross-sectional passenger flow data of a working day in May 2022 are shown in Figure 6. (a)the time-sharing passenger flow (b)The cross-sectional passenger flow Figure 6. The time-sharing passenger flow and cross-sectional passenger flow of a working day As can be seen from the above figure, the time distribution of passenger flow is uneven, and the combined operation mode of express-local trains can be implemented in the morning peak at 7:00-9:00 and in the evening peak at 17:00- 19:00. The upward and downward distribution of passenger flow in the section is relatively balanced, and both are convex. Therefore, the same fast and slow train scheme can be adopted for the upward and downward. In addition, non-stop express trains can be set up at the stations at both ends, and express train stops can be set up at the middle station. The route map of Wenzhou Rail Transit Line S1 is shown in the figure below. According to the previous research, only two stations can be set as overtravel stations, they are LongXia Road and LongTeng Road. Figure 7. The route map of Wenzhou Rail Transit Line S1 108 3.3. The Express-local Train Operation Plan 3.3.1. Basic Assumptions (1) The trains run at a fixed time interval, and all use a single route. Express trains do not stop at stations with less passenger traffic, while local trains stop at stations. (2) Express trains overrun the local train at the station, the local train waits at the overrun station to the auxiliary line, and the express train enters the station directly at the overrun station. (3) The number of trains on the whole line, the type of trains and the speed limit of each station are the same, and the additional time for starting and stopping of trains in each section adopts a unified standard. (4) Except for some local trains that need to extend the stop time due to avoiding express trains at over-travel stations, the rest of the trains strictly abide by the stop time standard. (5) Express trains cannot overtake adjacent express trains at two consecutive stations. 3.3.2. The Known Parameters The known parameters are shown in Table 3. The station number is set to 1 for TongLing and 18 for Shuang’Ou Avenue. Table 3. Value of Known parameters in case Parameter Name Meaning Value TR Study period 7:00-8:00, 7200s in total N Number of Stations on S1 18 stations v Train speed 22.22m/s a1 Train start acceleration 1m/s2 a2 train braking acceleration 1.1m/s2 T(Turn back) Train turnaround time 240s Table 4. Station dwell time and station spacing of Wenzhou Rail Transit Line S1 station number 1 2 3 4 5 6 7 8 9 Stop time/s 60 35 50 35 35 35 35 35 35 Station spacing/m 2286 3050 5880 2243 1947 2730 1873 5271 2179 station number 10 11 12 13 14 15 16 17 18 Stop time/s 35 35 50 35 50 35 35 35 60 Station spacing/m 3043 3892 1841 2247 7087 3583 1850 2005 3.3.3. The Express-local Train Plan At present, the interval between the morning peak hours of the S1 line is 600s. Taking the morning peak period from 7:00 to 9:00 as the research period, analyze the running plan when the ratio of local trains and express trains is 1:1, 2:1, 3:1, and 4:1 respectively. Due to the long interval between trains, combined with the passenger flow data analyzed above, if the express trains do not stop at the two stations, and the express train stops at the middle station. After checking, the express train can meet the minimum tracking interval without overtaking the local train. Therefore, the final combined operation mode of express-local trains is shown in Table 5. Table 5. The express-local train plan the ratio of local trains and express trains Departure interval /s local train departure frequenc y express train departure frequency Number of non-stop express trains Station number where the express train does not stop local travel time/s express travel time/s 1:1 600 6 6 8 2/3/4/13/14/15/16/17 3576 2983 2:1 600 8 4 8 2/3/4/13/14/15/16/17 3576 2983 3:1 600 9 3 8 2/3/4/13/14/15/16/17 3576 2983 4:1 600 10 2 8 2/3/4/13/14/15/16/17 3576 2983 When the driving time interval is less than 460s, overtaking will only occur. At this time, LongXia Road or LongTeng Road can be selected. At this time, the travel time of the local train will be extended, and the travel time of the express train will remain unchanged. 4. Conclusion Firstly, the applicability of the combined operation mode of express-local trains is analyzed, and different combined operation modes of express-local trains are proposed respectively for the unbalanced temporal and spatial distribution of passenger flow. After that, the express-local train schemes are studied, including the no-overrun express and local train scheme and the express train overrun scheme. After that, the influence of different express-local train schemes on the line passing capacity is analyzed, and the settings of non-stop express trains and express train overtravel stops are determined. Finally, taking the Wenzhou Rail Transit Line S1 as an example, combined with the actual 109 passenger flow data and travel plan data, the express-local train operation plans under different speed and local train ratios are determined, which provides a reference for enterprises to operate express-local trains. Acknowledgment Study on combined operation mode of fast and slow trains in urban railway -- Taking Wenzhou urban railway as an example, WZY2020024. References [1] Optimal Scheme of Train Stopping at Express-Local Train Station in Condition of Full-length and Short-run Routes.ZENG Cuifeng, HOU Yufei, LUO Qin, ZHOU Jun. [2] Proportion of Fast and Slow Trains Based on Passenger Flow Distribution on Urban Rail Transit Lines.HUANG Qiuyu, ZHAO Yuan, DING Xiaobing, LIU Zhigang, WAN Haochun, WANG Jing. [3] Optimization Model of Express/Local Train Stop Scheme in Urban Rail Transit Considering Energy Consumption. XU Sha, LUO Xia.