［Objective］The impact range of urban rail transit stations is difficult to accurately calculate through pure theoretical methods. It is necessary to approach the station impact range from an engineering application perspective through actual passenger feeder data under different feeder modes.［Method］Research parameters for urban rail transit station transportation are selected, and the calculation method for station impact range is determined. Taking typical urban rail transit lines in Osaka, Japan as the research object, the feeder range and sharing rate of stations under three feeder modes (walking, cycling, and road-based public transport) are calculated, and the distribution pattern of these data is analyzed. Two urban rail transit lines in Osaka City are selected to further investigate the impact range of suburban stations, and the correlation between the maximum station spacing and the impact range of urban rail transit stations is analyzed.［Result & Conclusion］The feeder range corresponding to 90% percentile of station passenger flow is adopted to represent the station impact range, which can effectively reflect the actual transport radiation capacity of the station. Under both walking and bicycle feeder modes, the feeder sharing rate and range display a decreasing trend from the core area to the suburbs. Under road bus feeder mode, the influencing factors of feeder range and sharing rate are relatively complex, and stations as transportation hubs and line terminals have relatively higher feeder sharing rates compared to other stations. For stations in suburban areas, the impact ranges of both the terminal station and interchange station are relatively large. With balanced land development around the station, its impact range shows a significant positive correlation with the maximum station spacing.

［Objective］Against the backdrop of urban agglomeration and metropolitan area development, territorial spatial governance, and the construction of a strong transportation nation, the characteristics and modes of passenger travel are becoming increasingly complex. It is necessary to study and leverage the role of passenger transport hubs in regional integration, spatial governance, and system coordination, in order to achieve an orderly expansion of spatial industries in metropolitan areas, a high-quality and intensive utilization of national territorial space, and the efficient organization of multi-level passenger travel.［Method］First, an evaluation framework for the existing passenger transport hub system in Shenzhen is established to assess passenger travel demands and characteristics, the functional hierarchy and construction concepts of passenger transport hub system are clarified, and goals of the passenger transport hub system are proposed, including efficient and smooth domestic and international connectivity, promotion of regional coordinated development, support for efficient urban governance, and integrated multi-network transportation. Second, a technical method for planning hub layout that integrates ′station-city-people′ is formulated. Factors such as centrality level, development density, interchange nodes, and travel hotspots are used as indicators for hub identification classification, and a qualitative and quantitative comprehensive evaluation is conducted to determine the layout of major hubs. Finally, differentiated development strategies for passenger transport hubs are explored to promote efficient hub system organization and high-quality governance of the surrounding land use.［Result & Conclusion］It is suggested to improve the urban functions of Shenzhen passenger transport hub one step further from three dimensions: the transportation dimension, further coordination is required regarding operating entities, system standards, and spatial implementation to achieve rail transit multi-network integration centered on passenger transport hubs; the urban dimension, detailed national spatial planning should guide the coordinated development of land around transport hubs; the regional dimension, industrial and land-use planning related to key intercity corridors and passenger transport hubs in Shenzhen metropolitan area needs to be optimized.

［Objective］By the end of 2022, the rail transit system in Suzhou had essentially formed a network. However, the overall passenger flow has remained relatively low, necessitating an evaluation of the passenger flow on Suzhou rail transit to identify key issues in its development and passenger flow enhancement.［Method］A multi-source data fusion analysis approach is utilized, incorporating mobile signaling data and rail transit gate data, to accurately control the users′ complete travel trajectories. Given the limitations of traditional OD (origin-destination) analysis, a grid-based division method is employed. From the perspective of supply-demand balance in urban rail transit, evaluation indicators are constructed from two dimensions: the residence/employment coverage rate (proportion of residential population and job positions) and the passenger flow conversion rate (proportion of urban rail transit trips). These indicators are used to analyze the passenger flow of Suzhou rail transit.［Result & Conclusion］Suzhou rail transit network generally aligns well with residence/employment distribution and the residents travel demand. However, certain high-density clusters of population and employment in areas such as Suzhou Industrial Park, Suzhou High-tech Zone, and Wujiang District exhibit weak rail transit coverage, highlighting the need to enhance bus-rail feeder services. Additionally, certain stations along Suzhou Rail Transit Line 3 and Line 5 show relatively low proportions of rail transit usage, indicating that the land-use layout and industrial structure may restrict the attractiveness to passengers.

［Objective］Rational urban planning control can effectively reduce the costs for metro project construction and operation, enhance the transport capacity and service quality of metro systems, and promote sustainable urban development. Therefore, it is essential to analyze and study urban planning control concepts and implementation strategies in metro engineering design.［Method］First, the importance of urban planning control in metro engineering design is analyzed, emphasizing its role in ensuring safe construction and operation, generating economic and social benefits, so as to meet environmental protection requirements. Then, six core concepts of urban planning control in metro engineering design and their theoretical foundations are explained. The application effectiveness of these concepts is demonstrated through relevant case studies in China and abroad. Next, Guangzhou Metro Line 11 is used as an example to verify the importance of urban planning control in metro engineering design, illustrating specific implementation methods in route planning, station layout, and operational models.Finally, representative metro projects in Beijing, Shanghai, and Guangzhou are selected to elaborate on key control points and implement strategies of urban planning when addressing project challenges such as environmental protection, route optimization, and land acquisition and demolition.［Result & Conclusion］Currently, shortcomings still exist in urban planning control in metro engineering design in China, while also facing new challenges and opportunities brought by the development of digital technologies. In the future, greater emphasis should be placed on the application of big data and artificial intelligence to enhance the accuracy and efficiency of urban planning control in metro engineering design.

［Objective］The construction disturbance caused by newly built stations with large-section rectangular interchange passage closely under-passing existing urban rail transit stations (hereinafter referred to as ′existing stations′) is significant, and there is a lack of relevant research on this topic. It is necessary to investigate the deformation and disturbance situation on the existing station caused by the newly built station closely under-passing.［Method］Based on the theory of conventional random media and its algorithm, an improved algorithm is proposed. Taking Jinfu Interchange Station of Chengdu Rail Transit as an example, relevant engineering calculation parameters are selected, and a three-dimensional numerical simulation model for the interchange station is established. The mechanical response of Chengdu Rail Transit Line 27 newly built Jinfu Station interchange passage closely under-passing existing Line 6 station is analyzed. The precision of improved algorithm and simulation model is verified through measured and simulated value comparison, and a sensitivity analysis of parameters is carried out.［Result & Conclusion］Through comparing measured and simulated values, the feasibility of the improved algorithm and simulation model mentioned above is verified. Constrained by the supporting piles, a bending moment or ′groove′ phenomenon appears on the structural base plate at the existing station. Additionally, with the increase of net spacing between the new interchange passage and the existing station, the most unfavorable part on the structural base plate shifts outward from the tunnel centerline. As the foundation reaction coefficient increases, the interaction between soil and the existing station intensifies, resulting in significant deformation, bending moment, and shear force on the structural base plate of existing station.

［Objective］Deep foundation pit excavation above existing metro tunnels may cause tunnel deformation. Vertical excavation with steel sheet pile support can reduce the amount of overburden soil removed from each segment, which is conducive to help control the tunnel uplift. It is required to conduct an in-depth analysis of the deformation effects of vertical excavation with steel sheet pile support on underlying metro tunnels.［Method］Based on a metro tunnel engineering, using numerical simulation method, two-dimensional and three-dimensional finite element models of a foundation pit retained by steel sheet piles are established, to simulate the dewatering conditions of the foundation pit and the conditions of different excavation steps separately. Then, through linear regression analysis, the impact of earthwork excavation on the settlement and horizontal displacement of the underlying tunnel is discussed. Through the verification model results and field-measured results, the influence of soil excavation on underlying tunnel settlement and horizontal displacement is discussed. After verifying model reliability with field-monitored data, tunnel uplift deformation under steel sheet pile support conditions is further predicted.［Result & Conclusion］Vertical excavation with steel sheet pile support can effectively control tunnel deformation. The peak settlement at underlying tunnel vault is greater and exhibits larger variation than that at arch waist, and the variation amplitude is bigger; the reduction coefficient for tunnel settlement dewatering impact obtained from monitoring data fitting is 0.05 to 0.30. In areas with greater overburden soil, the empirical reduction coefficient tends to be higher; the horizontal displacement is not under dewatering impact and no reduction is needed. It is predicted that after correction, in the steel sheet pile excavation section, the tunnel vault uplifts on east-line and west-line are approximately 3.3 to 5.7 mm and 4.5 to 6.6 mm, respectively.

［Objective］Due to the influence of geological conditions, tunnel burial depth, tunnel diameter, and properties of the overlying soil layer, the Peck formula exhibits significant deviations when applied to the shield tunneling construction in water-bearing sandy soil layers in Nanchang area. Therefore, a modification of the formula is necessary.［Method］Based on the field-measured data from a shield tunneling construction in a interval on Nanchang Metro Line 3, along with other measured data, the tunnel burial depth, tunnel radius, and internal friction angle of the overlying soil 3 primary factors that affect land subsidence are comprehensively considered. A calculation formula for land subsidence trough width applicable to Nanchang Metro shield tunneling in water-bearing sandy soils is derived. The range of formation loss rate is determined through inverse calculation using Peck formula. A correction coefficient for maximum subsidence is introduced to perform linear regression modification of Peck formula.［Result & Conclusion］The land subsidence curves predicted by the modified Peck formula closely match the measured subsidence curves, indicating that the formula can effectively predict land subsidence caused by metro shield tunneling construction.

［Objective］With the development of metro shield tunnel construction technology, large-diameter shield tunnel projects are gradually increasing. There are special geological conditions and tunnel structure for large-diameter metro shield tunnel in soft soil layer, thus it is necessary to conduct in-depth research on its bearing capacity.［Method］Based on the large-diameter shield tunnel project of Bainikeng Station to Dayun Station interval on Shenda (Shenzhen Airport to Daya Bay) Intercity Railway, the bearing capacity and damage evolution law of tunnel segment lining are revealed through refined modeling and analysis, and the bearing performance differences of tunnels with different diameters are clarified. Combined with field monitoring, the rationality of numerical study is demonstrated.［Result & Conclusion］With the increase of load, the lining structure experienced arch cracking, 2.0 mm arch bottom joint opening, over 0.2 mm arch waist outer crack width, arch bottom joint outer concrete yield, arch bottom bolt tensile yield and other key damage behaviors. The bearing process of large-diameter shield tunnel can be divided into four stages: elastic stress stage (the convergence deformation reaches 0 to <2.0‰D, D as the tunnel outer diameter), slight damage stage ( reaches 2.0‰D to <5.6‰D), rapid damage development stage ( reaches 5.6‰D to 9.4‰D), and near failure stage ( reaches 9.4‰D or more). Among them, the structure bearing state in elastic stage is good, the structure durability in slight damage stage is reduced, but the bearing safety is still good. So it is necessary to repair the structure in the rapid damage development stage.

［Objective］In the construction of metro tunnels in urban shallow-buried karst environments, it is of great significance to investigate the location of concealed karst caves and their effects on the disturbance of karst strata and the land surface response, which requires thorough analysis and research.［Method］Based on a typical karst tunnel of Guiyang Metro Line 3, a tunnel construction model in karst areas is designed, and a corresponding measurement system is established. Four conditions are selected: no karst cavity (condition 1), karst cavity developed at tunnel vault (condition 2), karst cavity developed at the left arch waist (condition 3), and karst cavity developed at the arch invert (condition 4). 12 excavation steps are designed, and the release of surrounding rock pressure, tunnel arch axial force and bending moment, and land subsidence are analyzed. The monitoring data are converted into engineering prototype results based on similarity ratios.［Result & Conclusion］The presence of concealed karst cavities leads to surrounding rock stress release within a certain range around the cavity. The final release values of surrounding rock pressure for conditions 2, 3, and 4 are 53.8%, 42.0%, and 67.6% of that in condition 1 respectively. The axial force and bending moment of the initial support under condition 3 are 132.9% and 175.6% of those in condition 1, making it the most unfavorable condition. The final land subsidence values at arch vault for conditions 2, 3, and 4 are 32.8 mm, 17.2 mm, and 23.0 mm, respectively, which are 172.6%, 90.5%, and 121.1% of the value in condition 1. The land subsidence amount and range have significantly increased under condition 2.

［Objective］To further enhance the mechanization rate of construction and establish a new underground excavation method compatible with local environmental conditions and large-scale machinery, tailored to meet the complex requirements of urban rail transit construction, the underground excavation method for large-span metro station in urban area is studied.［Method］Based on an analysis of urban topographical and geomorphological characteristics and the challenges faced in construction within urban areas, combined with practical experiences from underground excavation projects in Guiyang Metro, conventional underground excavation methods (such as arch cover method, double-side wall heading method, and central drift method) are thoroughly examined. Relying on the Beijing Road Station project of Guiyang Rail Transit Line 3, the ′arch-pillar method′-an innovative new underground excavation method that is highly compatible with environmental requirements is proposed.［Result & Conclusion］Through research, exploration and engineering practice applications, the arch-pillar method is comprehensively and meticulously discussed in terms of design concepts, construction procedures, and key technical controls. Practical results demonstrate that compared to traditional methods, this method offers advantages such as shorter construction duration, minimal disturbance to the surrounding environment, and lower engineering costs, propelling the innovative development of large-span metro station underground excavation method.

［Objective］The structural dynamics response of overlapping metro station under train loads is complex, often resulting in localized amplification of dynamics response and significant difference in dynamics behaviors across various structural locations. Therefore, it is essential to investigate the dynamics response law of overlapping station structures under train loading.［Method］Taking Zhongsheng Station, the cross-shaped intersect-overlapping interchange station on Nanjing Metro Line 7 and Line 10 as the research subject, a three-dimensional refined finite element model under complex stratum conditions is established. Considering the acceleration and deceleration effects of train entering/leaving station, as well as various sequences of train arrival/departure in the overlapping station，the dynamics response law of overlapping station structures under train loading are explored, the station structural deformation, vertical dynamic stress, and acceleration of existing station vertical vibration are analyzed. Multiple measuring points on different station cross-sections are selected, and vibration acceleration data at each measuring point under different working conditions and operating periods are compared through field measurements.［Result & Conclusion］Whether in terms of dynamics displacement and acceleration, or dynamics stress, the dynamics responses in overlapping sections are greater than those in non-overlapping sections. Compared to non-overlapping segments, the maximum dynamics displacement amplification factor at overlapping section measuring points is 4.57, the peak dynamics stress increases by a factor of 2.94, and the maximum amplification factor of vibration acceleration reaches 4.00.

［Objective］To enhance the safety of metro station foundation pit construction, it is essential to accurately determine the groundwater hydrogeological parameters, improving the accuracy of permeability and storage coefficient in confined aquifers particularly. This is a critical prerequisite for formulating dewatering schemes. Therefore, a more in-depth study of the hydrological parameters of confined aquifers in metro foundation pits is required.［Method］Based on the dewatering test at Sports Center Station on Ningbo Rail Transit Line 7, a three-dimensional transient groundwater seepage model is developed with Modflow6 software called via the Flopy module in Python language. An LSTM (long- and short-term memory) deep learning model is introduced to build a surrogate model of confined aquifer water level variations. Combined with a particle swarm optimization algorithm and based on field-measured data, an inverse analysis of the confined aquifer permeability and storage coefficients is conducted. Thereby a method for hydrogeological parameter inversion in metro foundation pits based on surrogate modeling and optimization algorithms is proposed.［Result & Conclusion］The obtained inverted vertical permeability coefficient is 0.76×10-5 m/s, the horizontal permeability coefficient is 1.38×10-5 m/s, and the storage coefficient is 6.42×10-5 m-1. When these parameters are input into the numerical seepage model, the calculated data closely matches the measured data in all process, including the stage of rapid water level drop in the initial pumping, the stage of gradual change during the stabilization period, and the stage of water level gradual recovery after pumping stops, validating the feasibility of the inversion method. The use of deep learning-based surrogate modeling combined with optimization algorithms enables efficient and accurate inversion analysis of groundwater parameters.

［Objective］In recent years, due to the influence of urban planning and layout, the number of small-radius curve tracks in urban rail transit construction is gradually increasing. To address the vibration and noise issues associated with small-radius curve tracks, it is necessary to study vibration and noise reduction measures and evaluate their effectiveness.［Method］Using the small-radius curve track section on a certain urban rail transit line in Beijing as research object, a vehicle-track-bridge coupled dynamics model and a rail finite element-boundary element acoustic radiation model are established by finite element and boundary element methods, respectively. Vibration and noise control measures for small-radius curve tracks are proposed，including specifically rail seamless welding and replacement with higher-grade vibration-damping fasteners. A simulation analysis of vibration acceleration and vibration levels after implementing the control measures is conducted to verify their effectiveness. Focusing on the primary source of train noise―wheel-rail noise, the inherent frequency, vibration modes, and acoustic radiation of the rail are calculated and analyzed based on the rail finite element-boundary element acoustic radiation model, and the wayside acoustic radiation before and after implementing vibration and noise reduction measures is compared.［Result & Conclusion］After applying the rail seamless welding vibration and noise control measure, the maximum vibration acceleration of the track bed decreases by 0.35 m/s2, and the maximum vibration level decreased by 1.42 dB. After replacing with higher-grade vibration-damping fasteners, the vibration acceleration of the track bed decreases by 1.05 m/s2, and the maximum vibration level decreases by 7.29 dB. The wayside sound pressure level decreases by 4.93 dB(A) after implementing the vibration and noise control measures.

［Objective］To address the issues of poor operational stability and ride comfort in the actual operation of single-axle monorail trains, it is aimed to investigate the rational values of minimum horizontal curve radius and curve speed limit for single-axle monorail trains from the perspective of track alignment.［Method］A vehicle-track coupled dynamics model for the single-axle monorail train is established, and the model′s validity is verified. The evaluation methods for operational stability and ride comfort of monorail trains are introduced. Based on requirements for different ride comfort levels, a recommended value range for the minimum horizontal curve radius of single-axle monorail train lines is proposed. The rationality of recommended value ranges is verified through simulation analysis. To achieve the coordinated alignment of track and curve-passing speed, the speed limit of single-axle monorail train in small-radius curve sections is further investigated.［Result & Conclusion］For a given design speed, the minimum horizontal curve radius of the line is primarily determined by the maximum over-height angle in the curve section and the unbalanced allowable train lateral vibration acceleration. When the train operating speed is less than or equal to 80 km/h, the minimum horizontal curve radius of 320 m for a single-axle monorail train line is adopted, together with a train operating speed limit of 4.30R(where R is the curve radius) in small-radius curve sections.

［Objective］Due to its excellent vibration and noise reduction performance, the floating slab track bed is widely used in urban rail transit. However, with the increasing service time, issues related to the deteriorating conditions of floating slab track gradually emerge, presenting significant challenges for the maintenance and management of floating slab track structure. It is therefore necessary to analyze the floating slab track bed defects and summarize corresponding treatment measures to provide references for floating slabs maintenance work.［Method］Taking the floating slab track bed maintenance work across the entire Shanghai rail transit network as the context, the working principles and structural characteristics of the floating slab are analyzed. The main types of defects, the impact characteristics, and causes of floating slab track structure within Shanghai rail transit line network are identified. A set of treatment measures such as precise load force adjustment, void filling, and replacement of failed components are proposed. Taking a rail transit line in Shanghai as example, its floating slab track defect treatment steps are analyzed concretely.［Result & Conclusion］Through various measures such as online monitoring, precise load force adjustment, and maintenance and component replacement, the service condition of floating slabs can be ensured. It is recommended to strengthen routine inspections in key sections, enhance the application of online monitoring technologies, and establish a big data platform to drive optimization in track structure design. This will enable the upgrade of preventive maintenance strategies and lifecycle cost control for floating slab track, comprehensively improving the proactivity and scientific basis of track structure operation and maintenance.

［Objective］When using sequential excavation methods such as central diaphragm walls and double-side heading techniques to construct large-span mined metro tunnels, temporary supports often hinder the effective use of large-scale mechanized operations. To meet the requirements of low-vibration mechanized construction in environmentally sensitive areas, it is necessary to develop the SAWS (superimposed arch wall system) method for large-span mined tunnel excavation and support, and to study its key technologies.［Method］After a brief introduction of SAWS (superimposed arch-wall support) method, taking a large-span single-arch mined metro station in Chongqing soft rock formation as an example, a numerical model is established using FLAC 3D software to simulate and analyze the geotechnical and structural mechanical behaviors during the entire station excavation process. A comparative analysis is conducted between Method 1 (conventional double-side heading method) and Method 2 (SAWS method) in terms of land subsidence, distribution of plastic zones in surrounding rock, deformation of initial support structure, stress in initial support structure, and axial force in system anchors, in order to verify the applicability and reliability of SAWS method.［Result & Conclusion］Compared to the double-side heading method, the SAWS method results in a maximum land subsidence increase of approximately 12.4%, in a maximum arch vault settlement of 8.5%, and 26.0% in maximum horizontal convergence within the tunnel along the direction perpendicular to tunnel line, all of which remain within safe margins. The internal force at the arch foot of the initial support is reduced by about 42.9%, and the axial force of system anchors in side wall middle and lower parts decreases by approximately 20.0% to 30.0%. The arch invert heave and the distribution of plastic zones in surrounding rock are essentially the same for both methods. SAWS method demonstrates sufficient safety and reasonable stress distribution in the initial support and anchoring structures. It can meet the requirements for large-scale mechanized construction and is feasible for implementation.

［Objective］The machinery construction method for link passages has been widely applied in 6-meter-class diameter shield tunnels, typically used in metro projects. However, there are few engineering practice cases and the limited research regarding its application in city railway tunnels, where 9-meter-class large-diameter shields are used.［Method］Focusing on a city railway project with 9-meter-class diameter shield tunnel, a three-dimensional load structure model of main tunnel and link passage is established. Under varying conditions of burial depth, soil parameter, and shield machine thrust, the impact of link passage construction on the main tunnel structure is analyzed from three aspects: deformation, axial force, and bending moment of special segments under different operating conditions.［Result & Conclusion］The additional deformation caused by the construction of link passage is influenced by both the burial depth and the thrust of the shield machine. When the burial depth is large, the link passage construction will increase the convergence deformation of the main tunnel; when the burial depth is small, it reduces the convergence deformation. An increase in shield machine thrust further reduces the convergence deformation of the main tunnel. Changes in the main tunnel internal forces are mainly concentrated in the steel segment sections of the three-ring special segments, where the axial force and bending moment at the arch waist of semi-open segment significantly increase, with the maximum occurring under operational conditions, which requires special attention during design. In contrast, internal force changes in the concrete segments are relatively minor.

［Objective］In rail transit inspection and monitoring, accurate mileage information of the track plays a critical role in the efficient utilization of inspection data. Therefore, it is necessary to study and design a precise sleeper localization technology.［Method］Due to certain errors in mileage positioning from images captured by track video inspection systems, the YOLOv8n object detection model is adopted to locate sleepers and ground electronic tags in inspection images and perform mileage correction. Based on the YOLOv8n model, a new EIoU (enhanced intersection over union) method is used. Through optimization of loss function and structural constraints on sleeper counting, a sleeper object detection model YOLOv8n~~SC is proposed based on the improved YOLOv8n model. A structural optimization algorithm is innovatively introduced, and the sleeper counting issue when sleepers are split across two adjacent images is solved, and structural constraints are provided to mitigate missed and duplicate detections. Taking a city metro line in Guangzhou as an example, the improved YOLOv8n~~SC model is applied to detect sleepers and electronic tags along the line and perform mileage correction. Thus, the scenarios of sleeper positioning missed and false detections are greatly improved.［Result & Conclusion］The improved and constrained sleeper positioning model YOLOv8n~~SC significantly enhances sleeper positioning accuracy, achieving a sleeper-level precise mileage positioning method with 100% accuracy. Without requiring additional system equipment, the YOLOv8n~~SC model improves the mileage accuracy of the inspection image acquisition system, providing strong practical feasibility.

［Objective］In green belt embedded tracks, the condition of fasteners cannot be directly observed, and measurements of rail geometry alone cannot intuitively reflect the fastener clips loosening or failure. As a result, timely and effective maintenance may not be implemented, leading to degradation of track alignment conditions. Therefore, it is necessary to study the influence of fastener clip loosening and failure on rail head lateral displacement in green belt embedded tram tracks.［Method］A rail overturning analysis model is established using finite element method. The rail is modeled with solid elements, while fastener clips, elastic baseplates, and lateral supports are modeled with nonlinear spring elements. The variation of clamping force is simulated by controlling the downward displacement of the spring, representing the clip pressure. The wheel-rail forces are divided into vertical and lateral components, applied as concentrated loads. The model is used to evaluate changes in rail head lateral displacement and contact length between the rail and elastic baseplate under various conditions, such as simultaneous failure of clips on both sides, failure on the inner side only, failure on the outer side only, and in the case of track gauge block detachment, under different amounts of clip loosening and varying numbers of failed clips.［Result & Conclusion］Under smaller wheel-rail lateral forces, the degree of clip loosening, the track gauge block detachment and the number of failed clips on both sides without detachment have minimal impact on rail head lateral displacement. When lateral forces increase, rail head lateral displacement will increase with greater clip loosening, though the trend remains gradual. Rail head lateral displacement also enhances as the number of failed dual-side clips increases. Under the same conditions, comparison between scenarios with and without track gauge block detachment shows similar rail overturning angles, but the lateral displacement of the rail base leads to an increased rail head displacement. When clips fail on the inner side, rail head displacement increases with more failed clips; the opposite effect is observed when clips fail on the outer side.

［Objective］To minimize passenger travel time while reducing operational costs for enterprises, it is necessary to identify an optimal balance between these two competing objectives. A systematic study on the stop plan for express/local trains on city rapid rail transit lines should be conducted based on both passenger travel costs and enterprise operational costs.［Method］Based on the characteristics of city rapid rail transit lines, a bi-objective nonlinear optimization model is developed, aiming to minimize passenger travel time and enterprise operational costs. According to genetic algorithm theory, a corresponding genetic algorithm program is constructed and the model is solved. Using an actual city rapid rail transit line as a study case, passenger flow OD (origin-destination) data during the morning peaks on a typical working day is used as the input. The optimal express/local train stop plan is obtained after line optimization using genetic algorithm. A comparative analysis is conducted on enterprise operational costs and passenger travel costs before and after the stop plan optimization.［Result & Conclusion］The stop plan verifies the effectiveness of the proposed model and algorithm. While the optimized stop plan for express/local trains on city rapid rail transit lines reduces passenger travel costs by 19.48%, increases enterprise operational costs by 4.23%, and leads to an overall cost reduction of 4.18%. Although the algorithm slightly increases operational costs for enterprises, it significantly reduces passenger travel time costs and improves overall passenger travel accessibility.

［Objective］In response to the growing pressure of urban rail transit passenger flow, train virtual coupling technology possesses significant advantages in enhancing urban rail transit train operation efficiency, alleviating constraints on line transport capacity, and adapting to uneven spatial and temporal distribution of passenger flow. It is thus necessary to study its specific temporal-spatial parameters.［Method］Based on the conventional safety braking model, a train safety braking model for virtually coupled train formations in urban rail transit is established to calculate and derive the minimum safe distance between train units under ideal conditions. Building on this foundation and through simulation calculations, the temporal-spatial parameters under time-saving operation mode, such as train coupling and decoupling duration and zone length are obtained. Furthermore, a sensitivity analysis is conducted on two selected parameters: the time required to establish train-to-train communication and the maximum permissible speed between sections.［Result & Conclusion］Under identical train operating speeds, the minimum safe distance between trains in virtually coupled train units is significantly smaller than that in traditional tracking modes, and the increase of train operating speed will cause an increase in the gap between them. When train operating speed is 60 km/h, the minimum safe distance between trains in the former shortens by 75.7% in comparison to the latter. The time required to establish train-to-train communication has a substantial impact on train coupling. With a train-to-train communication range of 30~60 seconds, the increment amplitude of train coupling duration and zone length goes up to 103.4% and 100.4%, respectively. Given that train operational safety is ensured, setting a higher maximum allowable interval speed is more conducive to the optimal curve running of train application, thereby shortening train coupling duration and zone length.

［Objective］The capacity bottlenecks and parallel operations throughout the full-process of integrated train dispatching from metro vehicle bases are not fully touched in existing section-based dispatching capacity studies. Therefore, it is necessary to focus on the complete process of trains operating from the stabling and inspection garages to the mainline platforms, systematically analyze dispatching capacity bottlenecks, and propose a calculation method for the integrated dispatching capacity of metro vehicle bases during morning peak hours, providing theoretical support for the evaluation and optimization of depot dispatching capabilities.［Method］Based on the section division method, the throat area passing capacity within vehicle depot under train routing and coordinated dispatch-routing modes, as well as the additional train insertion capacity at connection stations under different insertion routes, a detailed capacity calculation model is established by introducing operational timetables and time-distance diagrams. Further analysis is conducted on the capacity bottlenecks of different sections and the parallel operation processes. For both single-track and double-track dispatching scenarios, an integrated dispatching capacity calculation method for metro vehicle bases is proposed. Theoretical calculation results are compared with actual operational data from the Luogang Depot of Guangzhou Metro Line 6 to verify the reliability of the method.［Result & Conclusion］Under the double-track dispatching mode at the above-mentioned depot, the theoretical minimum dispatching interval during morning peaks is 223.6 seconds, corresponding to a maximum dispatching capacity of 17 trains per hour. In actual operation, the observed dispatching headway during morning peaks is 222.6 seconds, with 17 trains dispatched, resulting in a deviation of only 0.45% from the theoretical value, thus verifying the reliability of numerical calculation.

［Objective］Implementing precise initiation, performance evaluation and dynamic information dissemination of metro station large passenger flow management and control measures requires more effective support. It is necessary to consider the diversity of facility types and the concurrency of congestion from the perspective of passenger flow streamlines. A congestion state real-time evaluation model of metro station passenger flow streamline for assessing real-time passenger flow conditions is established.［Method］Passenger flow streamline facilities are categorized into node facilities and passageway facilities. Based on the spatiotemporal propagation characteristics of streamline congestion and the feasibility of extracting passenger flow parameters via video recognition technology, three evaluation indicators―average delay time at all node facilities, queue space overflow rate at all node facilities, and variation coefficient in walking speed across all passageway facilities―are defined and formulated. Targeting dynamic information dissemination, the instantaneous congestion level classification criteria for a given station streamline is determined based on ant colony clustering algorithm, and the CRITIC method (an objective weighting approach) is used to determine the weights of streamline instantaneous congestion indicators. Taking the east station-hall main inbound passenger flow streamline of Shanghai Rail Transit Caohejing Hi-Tech Park Station as a case study, the streamline′s instantaneous congestion levels are analyzed, as well as the changes in streamline overall congestion levels under different congestion information dissemination intervals.［Result & Conclusion］The congestion state of passenger flow streamline is related to that of multiple individual node facilities. By conducting a comprehensive analysis, this model provides a more holistic basis for determining the initiation timing, sequencing, and effectiveness of large passenger flow management and control measures across diffe-rent levels of nodes and streamlines.

［Objective］To effectively address the pressure of inbound/outbound passenger volume on metro lines during peak hours, it is necessary to develop an accurate passenger volume prediction model to understand the spatiotemporal distribution patterns of metro station inbound/outbound volumes and enhance the scientific basis for operational and scheduling decisions of metro lines.［Method］Passenger volume data from Hangzhou Metro is selected, with an introduction to the types of data and the requirements for data preprocessing and analysis. Building upon the LSTNet (long- and short-term time-series network) model, a Bi-LSTM (bidirectional long- and short-term memory) model and the attention mechanism are incorporated to establish an improved LSTNet prediction model. Furthermore, a metro passenger volume prediction method integrating multi-scale temporal sequence features is proposed. Passenger flow data from 6 Hangzhou Metro stations are selected, and predictions are carried out using the LSTM model, the LSTNet model, and the improved LSTNet model respectively. Based on the prediction results, the performance of the improved LSTNet model is evaluated.［Result & Conclusion］Compared with the adopted LSTM and LSTNet models, the improved LSTNet model reduces the mean absolute percentage error (MAPE) of total passenger volume prediction at metro stations by 5.3% and 2.4%, respectively. The improved LSTNet model significantly enhances the accuracy and stability of metro passenger flow prediction.

［Objective］Compared to metro, city rapid transit lines are characterized by longer routes and greater passenger travel distances. Operating express/local trains can increase travel speed and improve travel efficiency for passengers. Therefore, it is necessary to study the passenger flow impact of such express/local train operation plans and analyze the travel characteristics of passengers on these lines.［Method］Guangzhou Metro Line 21 (identified as a city rapid rail transit line) is selected as the research object to analyze the passenger flow adaptability of this line operation plan and describe its current operating conditions. Based on the line′s entry/exit smart card data, the temporal distribution characteristics of passenger trips under the current express/local train operation plan are analyzed. A 3-minute interval passenger flow matrix is extracted as the input for modeling. Using VISUM software, a timetable-based passenger flow assignment model is established to output passenger flow indicators for the express/local train operation plan. Problems of the current plan are analyzed and directions for optimization are identified.［Result & Conclusion］The current express/local train operation plan on this line demonstrates significant time-saving effects. The express train has a strong appeal to peripheral passenger flow, with a clear boarding peak appearing at peripheral stations before the express train departure. To further optimize the operation plan, issues such as long intervals between express trains and inconvenient interchanges between express and local services should be addressed.

［Objective］The domain adaptation issue among metro track images results in low segmentation accuracy for track-wheel images with high inter-class similarity in existing algorithms. To address this challenge, a few-shot metro track-wheel image segmentation algorithm based on a cross-attention network is proposed.［Method］The computational roadmap and process of the few-shot metro track-wheel image segmentation algorithm based on cross-attention network is elaborated. First, a group of backbone networks with shared weights is employed to map the input track-wheel images from both the support branch and the query branch into a deep feature space. Then, the low-, mid-, and high-level features from the dual-branch mappings are fused across scales. A cross-attention network is used to mine the relational semantics between these fused features, enabling the capture of shared semantic information in the deep space across different metro track-wheel images belonging to the same class. Finally, an average pooling is applied to convert the common features of both branches into class-specific prototypes, and the prototypes are leveraged to guide the segmentation of unannotated track-wheel images in the query images. Comparative and ablation experiments are conducted on a self-constructed metro track-wheel image dataset to verify the accuracy and effectiveness of the algorithm.［Result & Conclusion］Testing shows that the proposed algorithm achieves a mIoU (mean intersection over union) of 66.17% and a foreground-background intersection over union (FB-IoU) of 78.21%. Compared with current mainstream semantic segmentation algorithms, the proposed few-shot metro track-wheel image segmentation algorithm based on cross-attention networks demonstrates significantly improved segmentation performance and shows potential for practical application.

［Objective］To address the damage to wheel treads, brake shoes, and the thermal cracks caused by frequent braking and sharp temperature rises in friction pairs of urban rail transit trains in operation, it is necessary to establish an accurate temperature rise model to investigate the evolution law of temperature fields under different braking conditions.［Method］A three-dimensional transient temperature rise simulation model considering the contact thermal conductivity coefficient of the wheel-brake shoe pair is developed based on heat conduction theory. The ABAQUS finite element software is employed to numerically simulate the temperature field of the friction pair. During the model construction, key factors such as contact thermal conductivity coefficients, material thermophysical parameters, and convective heat transfer coefficients are comprehensively taken into account, and the grid independence verification ensures computational accuracy. Working conditions for a train load are set to AW3 full capacity (abnormal weight), the initial operating speed to 80 km/h, and the braking deceleration to 1.2 m/s2. The temperature variation of the wheel-brake shoe friction pair is analyzed through simulation under conditions of a single emergency braking and three consecutive emergency brakings.［Result & Conclusion］Under the single emergency braking working condition, the surface temperature difference of the brake shoes considering and neglecting the contact thermal conductivity coefficient is 71.17 ℃; axial temperatures of the brake shoes are concentrated in its central region, while radial temperatures are primarily distributed on brake shoe surface with significant temperature gradients. Under the three consecutive emergency braking events, the brake shoe simulated temperatures are 217.40 ℃, 245.78 ℃, and 270.70 ℃, respectively; compared with experimentally measured temperatures, the maximum error between them is 3%.

［Objective］With the continuous development of urban rail transit and the ongoing expansion of metro lines, the service environment for metro vehicle bogies is becoming increasingly complex. This poses new challenges to the operational safety and reliability of bogies. Therefore, it is necessary to study the actual in-service performance of metro vehicle bogies under complex conditions.［Method］The vehicle bogies of a Shenzhen Metro line are selected as the research object and their long-term in-service performance study is carried out. Comprehensive line-tracking tests are conducted targeting test lines and test scenarios under various working conditions, with multiple rounds of testing performed within a single wheel reprofiling cycle. Data are systematically collected on wheel conditions, dynamics performance, structural strength, and vibration characteristics of metro vehicle bogies under real operation conditions. Trends for wheel radial runout distribution, wheel out-of-roundness characteristics, equivalent conicity, and rolling circle wear are obtained. Vibration acceleration test data of bogies are acquired by placing test points, and the dynamics performance evolution law of bogies is comprehensively analyzed in conjunction with the wheel condition data. Additionally, eight key dynamic stress measurement points are arranged on the bogie frame to observe changes in critical stress locations under the unloaded and the peak passenger load two operating conditions.［Result & Conclusion］Since wheel radial runout has the greatest impact on wheels, periodic monitoring of wheel radial runout should be strengthened. The weld joint at the motor suspension bracket is identified as a high-risk location, requiring regular monitoring and maintenance.

［Objective］The signaling system for Xi’an Metro Line 2 Phase Ⅰ project (hereinafter referred to as Line 2) utilizes an imported system, while Phase Ⅱ adopts a domestically developed system. The Phase Ⅱ project is an extension line of Phase Ⅰ, and the signaling systems of both must be fully interoperable to enable seamless operations. Additionally, Phase Ⅱ must enhance the functionality and performance based on the existing Phase Ⅰ project. Therefore, it is necessary to conduct a targeted study on the compatibility implementation plan for the signaling systems across the two phases.［Method］Based on an overview of the compatibility implementation strategy, specific compatibility solutions are designed for key subsystems, including the ATS (automatic train supervision) subsystem, interlocking subsystem, wayside ATP (automatic train protection) subsystem, on-board ATP/ATO (automatic train protection/operation) subsystem, and DCS (data communication subsystem). A compatibility test environment is constructed on the test track and the main line of Line 2, and one train is retrofitted with domestically developed on-board equipment to verify the compatibility solution effectiveness for the proposed Line 2 signaling system after implementation.［Result & Conclusion］The compatible implementation plan successfully enables the safe and reliable interoperation between phase Ⅰ and Ⅱ project signaling systems, while significantly enhancing the signaling system overall performance. Following the implementation, the operational efficiency of Line 2 is significantly improved.

［Objective］With the high-speed development of urban rail transit, the drastic increase of passenger volume puts forward higher requirements on the train departure interval. In order to optimize the information transmission process, shorten the train departure interval and meet the higher operational needs, it is necessary to analyze the limitations of the adopted vehicle-wayside communication mode in CBTC (communication-based train control) system when calculating movement authorization, and study a new optimized movement authority method.［Method］The definition of movement authorization and its calculation principles are introduced, and the differences between CBTC system and TACS (train autonomous control system) are analyzed. A train interval control method based on cellular automata is proposed, and a movement authorization calculation model considering relative speed is constructed, to optimize movement authorization from the model level. Taking the alternate post-station turn-back at Shenzhen Metro Line 3 Liyuan Station as an example, the movement authorization optimization model proposed from using MATLAB software is verified under both CBTC and TACS systems.［Result & Conclusion］When the turnout speed limit is 35 km/h, the post-station single-track turn-back time interval under TACS is 34 s shorter than that under CBTC system, significantly improving train departure efficiency.

［Objective］To meet the integrity, confidentiality and availability requirements for inter-network video transmission of different security levels in urban rail transit system, it is necessary to develop a secure and reliable one-way video transmission scheme that ensures video data flows only from low security networks to high security networks.［Method］A one-way video transmission scheme based on two endpoint devices is proposed. The overall architecture of the scheme is introduced, and a proprietary Ethernet-based protocol is designed. UPET (unidirectional private exchange tunnel) technology is employed for the design of one-way transmission channels, and FEC (forward error correction) technology is used for error correction and verification design. Based on these, the data transmission process of the proposed scheme is established. Relevant software and hardware are integrated to validate the testing effectiveness of the proposed scheme, and the actual performance of the scheme is evaluated over a one-month operational period on multiple urban rail transit lines in Shanghai.［Result & Conclusion］Compared with conventional UDP (user datagram protocol) transmission methods, the proposed one-way video transmission scheme demonstrates more stable data transfer rates and lower latency, meeting the real-time transmission requirements of urban rail transit services. The proprietary protocol design in the proposed scheme effectively avoids the vulnerabilities associated with general-purpose protocols and enhances resistance to network attacks, thereby ensuring synchronous video transmission across classified networks.

［Objective］Aiming to design and construct a high-performance, high-reliability intelligent O&M (operation and maintenance) system for urban rail transit communication and to formulate scientific maintenance strategies, it is necessary to transform traditional periodic scheduled maintenance to condition-based maintenance according to test analysis, and to prior assessment-based predictive maintenance, thereby reducing the probability of equipment failure and operational costs. Furthermore, it is to shift from traditional manual O&M management to an automated, information-based intelligent monitoring and maintenance approach.［Method］In combination with the on-site practice, associations are established between virtual entities and physical entities such as communication systems and key equipment to investigate equipment monitoring and diagnosis models. The multi-source heterogeneous data fusion and analysis technologies are applied to communication system fault diagnosis and prediction. An equipment health index algorithm model and a big data architecture are proposed, and a tracking and evaluation platform encompassing ′cloud-data-intelligence′ is built. This platform provides both a theoretical basis and a validation environment for on-site pre-diagnostic maintenance, enhances the coverage of condition awareness, the accuracy of diagnosis and prediction, thus significantly improving the quality of O&M.［Result & Conclusion］The engineering application of the intelligent communication intelligent O&M system on Nanning Rail Transit Line 4 achieves comprehensive equipment monitoring, extensive fault response mechanism, and advanced human-machine interaction. Application results show that this intelligent communication O&M system enhances the intelligent O&M level of rail transit communication equipment and enables a shift from traditional periodic maintenance to health-based intelligent monitoring and predictive maintenance.

［Objective］In response to four major challenges faced in the development of urban rail transit O&M (operation and maintenance), Nanning Rail Transit Line 4 is taken as the practice platform to construct an intelligent O&M system for signaling system driven by data and intelligent decision-making. The goal is to break through the technical and managerial bottlenecks of traditional O&M models and achieve efficient, precise, and sustainable O&M system.［Method］By integrating multi-source heterogeneous data and building a multi-layer architecture, the system enables real-time equipment status monitoring and degradation trend analysis, significantly improving data utilization and fault identification capabilities. By leveraging complex network theory and equipment failure mechanism analysis, a fault prediction model covering key equipment is developed to support automatic fault localization and early warning. In terms of management, through refactoring digital workflows, allocating light-asset material, and establishing cross-disciplinary integrated teams, the O&M system eliminates traditional data silos and professional barriers, forming an ecosystem encompassing ′personnel-equipment-material method synergy′.［Result & Conclusion］In the engineering application of Nanning Rail Transit Line 4, this intelligent system promotes three major transformations in the O&M model: from passive response to proactive prevention, from experience-driven to data-driven, and from fragmented management to coordinated optimization. Practice has demonstrated that the intelligent O&M system, empowered by intelligent technologies and process re-engineering, significantly enhances O&M efficiency and equipment reliability, offering a replicable solution for the industry. Research in the future will further explore the application of cutting-edge technologies such as artificial intelligence and machine self-learning in intelligent O&M systems, promoting the evolution of rail transit O&M system towards greater intelligence and sustainability.

［Objective］The existing 40.5 kV AC comprehensive protection device of urban rail transit (hereinafter referred to as AC CPD) relies on imported system-level chips, which greatly restrict the localization of equipment, so it is urgent to localize the software and hardware development of AC CPD.［Method］The structure and function of the existing 40.5 kV AC CPD equipped with system-level imported chips are briefly described. Based on the localization requirements of 40.5 kV AC CPD in China′s urban rail transit, a domestic chip design scheme with dual FPGA (field programmable gate array) integration based on SPI (serial peripheral interface) bus expansion technology is proposed. The hardware electromagnetic compatibility test, software protection function test, and performance test in high temperature and high humidity environment are carried out on the localized AC CPD equipped with domestic chips, and the main performance indicators of the localized and the existing AC CPD are compared. Finally, the application of the localized AC CPD adopted in urban rail transit engineering is briefly described.［Result & Conclusion］The test results of hardware electromagnetic compatibility and software protection function for the localized AC CPD meet the requirements of the State Grid, and its main performance level is equivalent to that of the existing AC CPD. The device is stable and reliable in the application project, and the performance is excellent. The application of this device can effectively solve the problems of incomplete categories, limited performance, and insufficient interface of some domestic devices, and fundamentally solve the problem of relay protection key components and software operating systems heavily dependent on imported equipment.

［Objective］To enhance the intercity commuting capacity, newly built city rapid transit lines adopt a 27.5 kV AC (alternating current) traction power supply system, enabling higher operating speed. While improving train transport capacity, AC traction power supply also increases external leakage currents, resulting in excessive ground return currents. Therefore, it is necessary to conduct an in-depth research on ground return current composition in metro line main substations using AC power supply system.［Method］Focusing on a city rapid rail transit line in Guangzhou that adopts AC traction power supply system, the composition and ground return path of current return system at the traction substations that supply power to both stations and depots is studied. To determine the proportion of ground return current within the total return current, tests on return current are conducted during the joint commissioning and testing phase before the line opened. The return current of traction substation is tested, the wiring layouts are investigated on-site, and current measurements of the copper-clad steel grounding body are performed. On this basis, tests on earth soil return currents are conducted, and improvement measures for ground return are proposed.［Result & Conclusion］The primary reason for excessive ground return current at the main substation is the presence of return current through copper-clad steel structures. In addition to the known station and depot cable returns and earth soil returns, there exists an additional return path through cable trench supports, accounting for more than 25% of the traction current flowing back to the traction substation grounding grid via this path, thereby leading to larger results from ground return current measurements. After implementing the proposed improvement measures, the proportion of current returning through earth soil decreased to approximately 30% of the total return current, achieving an excellent level of ground return quality.

［Objective］To enable accurate determination of DC (direct current) bus overcurrent protection in metro DC traction power supply system and enhance the selectivity of fault tripping in the system, the research on a suitable DC bus overcurrent protection scheme is required without increasing equipment or current sampling circuits.［Method］The current direction and protective operation status of various circuits connected to the DC bus are analyzed under various operating conditions of metro DC traction power supply system. Boolean logic calculations are used to extract and refine the logical basis for bus overcurrent protection. An engineering implementation scheme based on GOOSE (generic object-oriented substation event) information exchange is proposed, with an extension of the logical nodes for DC bus overcurrent protection. A circular network test platform based on HSR (high-availability seamless redundancy) is constructed to simulate and analyze the following four scenarios of DC power supply system: normal operation, bus fault, upstream fault on the DC incoming line, and DC feeder fault.［Result & Conclusion］The proposed scheme could determine bus faults by detecting forward overcurrent protection actions on incoming and outgoing lines of the DC bus. It meets the requirements for protection reliability and speed, offering a DC bus protection solution that integrates low cost, high reliability, and simple implementation. The scheme ensures reliable tripping for bus faults and satisfies the selectivity and rapid response requirements of protection devices.

［Objective］Due to the significant difference in soil characteristics compared to other types of soil, such as pH value, salinity, and soil resistivity, the red soil features more severe corrosion of metal facilities along metro lines caused by the stray current in its environment. Therefore, it is necessary to thoroughly analyze the distribution law of metro system stray current in red soil regions, exploring effective protection measures against stray current in such environments.［Method］The distribution law of current density and potential gradient of stray current in soil is analyzed. A simulation model of metro line stray current is established to analyze the transverse and longitudinal distribution law of metro stray current in red soil environments, as well as the associated potential gradient distribution. The red soil is compared with three typical types of soil (desert soil, alpine soil, and saline-alkali soil) and the differences in stray current distribution under various soil conditions are studied. The influence law and impact range of rail resistance, rail-to-earth resistance, and power supply voltage on the ground potential caused by stray current in red soil are also analyzed.［Result & Conclusion］In red soil environment, stray current gradually decreases from the centerline of metro line toward both sides, and after dissipation through the soil, a recovery phenomenon occurs near substations. Compared with the other three soil types, the stray current in red soil has a wider impact range. Measures such as reducing the longitudinal resistance of rails, increasing the rail-to-earth resistance, and raising the power supply voltage can effectively reduce the impact of stray current in red soil.

［Objective］With the rapid development of urban rail transit, public safety issues are becoming increasingly prominent. It is essential to establish an advanced and standardized system framework and conduct research on public safety system technologies. A new mode for precise security screening in urban rail transit is explored for the travel safety and convenience enhancement.［Method］By advancing the standardization of public safety technology and prevention in urban rail transit, field research is organized to explore new directions in the development of security screening technologies. Based on precise screening technologies and an intelligent interactive platform, a new mode for efficient and precise screening is studied to address existing problems and challenges in current security screening practices. Additionally, application demonstration projects for the new security screening mode and system are carried out to verify the newly established standardized equipment and their system functionalities.［Result & Conclusion］By leveraging key technologies such as intelligent passenger credit evaluation, real-time identity verification, precise identification of prohibited items, and intelligent coordinated response, an efficient and precise security screening system is established. This system reshapes the screening process, supports performance evaluation and application demonstration, and provides technical support for building a safe and convenient urban rail transit service system. It also offers important references for revising related standards and exploring new technologies, thereby further enhancing the public safety prevention capabilities of urban rail transit in China.

［Objective］In the planning and practice of digital transformation of urban rail transit electromechanical system in various cities, it is necessary to carry out architecture reconstruction and functional redefinition for automatic fare collection system (hereinafter abbreviated as AFC) to adapt to digital transformation.［Method］Based on the guidance on the construction of the Shanghai Metro electromechanical system, a cloud edge three-layer architecture for the on-site layer, station layer, and network layer is proposed. Combined with the current practice of Shanghai Metro AFC connected to the station digital operation platform, a two-layer architecture system of Shanghai Metro AFC center layer and equipment terminal layer is proposed on the basis of conventional automatic ticketing system architecture. The functions of the two-layer architecture are redefined, and the network composition between each layer is introduced.［Result & Conclusion］After the reconstruction of Shanghai Metro AFC, a direct network connection is adopted between the two layers of the system architecture, to adapt to the business characteristics of the AFC system. The terminal equipment layer is connected to the station digital operation system to meet the integration requirements of the station daily electromechanical system management, and the service functions in the station digital operation platform are also clarified. The restructured system architecture adapts to the changes brought by digital transformation, combines system business with operational management under digital transformation, resulting in simplified management hierarchy and reduced construction investment.

［Objective］In response to the structural characteristics of the dual end layout for underground station equipment, fully utilize the configuration of BAS (building automation system) A-end and B-end PLC (programmable logic controller) equipment, and maximize the system redundancy, a networking optimization and multi-level redundancy scheme for station BAS is investigated.［Method］A method of implementing the networking optimization and multi-level redundancy for metro BAS and PLC systems is proposed. This method improves the original system architecture through non-differentiated networking of multiple controllers and remote I/O (input/output), multi-level PLC redundancy architecture, and operational strategy optimization.［Result & Conclusion］The optimized system effectively prevents station BAS from becoming uncontrollable in the event of a master PLC failure, thereby enhancing the overall system reliability and emergency response capability. In particular, under extreme conditions, the optimized system ensures the stable execution of emergency modes to the greatest extent possible, effectively safeguarding station operational safety.

［Objective］Interoperability is a major trend in current rail transit development, and the cross-line through operation of trains with different systems is a key operational scenario of such interoperability. Since different train types vary in the number, position, and opening dimensions of passenger compartment doors, the PSD (platform screen door) must be compatible with a variety of train configurations. To better meet the safety, efficiency, and convenience requirements of passenger boarding/alighting in interoperability scenarios, it is necessary to conduct in-depth research on PSD compatibility schemes and structural performance, taking into account the train-type characteristics and load environments of intercity railways, city (suburban) railways, and urban rail transit vehicles.［Method］Taking the cross-line operation of Type-D and CRH6 trains as the research object for the through operation scenario, and based on the characteristics of passenger compartment door positions and parameters for through-operation trains, a side-hinged and telescoping composite compatible PSD typical structure and a full-side compatible PSD layout scheme are proposed. A finite element analysis model is established to calculate and verify the structural strength of compatible typical PSD configuration under the most unfavorable load conditions in an interoperability scenario.［Result & Conclusion］Under the most adverse load condition of passenger crowd pressure, wind load, passenger impact, and seismic forces simultaneous action, the structural strength and stiffness of the compatible PSD fully meet regulatory requirements. The proposed typical door structure effectively resolves the compatibility challenges of PSD systems under the complex working conditions of cross-line operations involving different train-type configurations.