Bidirectional substations have advantages in regenerative braking energy utilization of urban rail transit because of their controllable output voltage, capability of unity power factor operation, and bidirectional energy flow. Due to voltage sensor errors and line parameter inconsistencies, the two converters in the substation generate significant unbalanced currents. While increasing the converter output current feedback coefficient can reduce the current difference between converters, it consequently intensifies the output voltage fluctuations of the substation. On the basis of droop control strategy based on converter output current feedback, a droop control strategy based on substation output current compensating voltage command value is proposed by adding a voltage compensation term proportional to substation output current. The results show that this strategy can improve the current balance between converters and reduce the fluctuation degree of substation output voltage. Finally, the simulation model is built in MATLAB/Simulink, and the example analysis is carried out to verify the effectiveness of the proposed strategy.

This paper presents a comprehensive assessment of embedded rail technology implementation in existing metro line renovation through the case study of Xiaogang Station. The research examines the technical challenges, innovative solutions, and construction methodology employed in this pioneering project. The construction background, distinctive features, construction procedures, and solutions to the construction challenges encountered are introduced in detail. By comparing the preand postrenovation vibration, noise and Track Quality Index (TQI) on track, along with the monitoring of the postrenovation track condition, this study demonstrates the effectiveness of embedded rail track renovation in enhancing the performance of existing lines. The results indicate that this technology can significantly improve the vibration and noise reduction performance of the line while ensuring the continuity and safety of existing line operations.

The lowaltitude economy has become a new industrial direction pursued in global competition due to its prominent features. The research on lowaltitude economy in the field of urban rail transit is rapidly developing and growing. For the low and medium capacity rail transit systems represented by the straddle monorail system, based on the key technology research of low altitude technology, it is necessary to explore a low altitude unmanned aerial vehicle intelligent inspection system that is suitable for the construction and operation characteristics of straddle monorails, meets operational requirements, and effectively solves maintenance problems. This study proposes for the first time a video intelligent inspection system based on an unmanned aerial vehicle platform applied to straddle monorail transit, analyzes its application plan scheme and value in straddle monorail transit, and explores a practical and feasible low altitudeeconomic economy application scenario for the low and medium capacity rail transit systems mainly based on elevated laying structures. This approach is conducive to achieving the automation of straddletype monorail transit track beam and bridge inspection. This approach is effective in Reducing the workload of manual inspections and minimizing manual omissions has significant implications for the industry.

Relying on a subway station entrance and exit channel pipe jacking project, combined with the onsite monitoring data for jacking parameter inversion, the refined pipe curtaincorridorstrata pipeline corridor jacking finite element model considering the locking joints was established. The deformation of strata with and without pipe curtain is analyzed comparatively, and the necessity of pipe curtain is verified. Then, the effects of pipe diameter, pipe spacing and pipe thickness on surface settlement, pipe curtain cost and joint gap were systematically investigated through comprehensive tests, and a comprehensive evaluation system of TOPSIS was established to evaluate the adaptability of the pipe curtain with game combination assignment. Subsequently, BPNN was used to fit the mapping relationship between the pipe curtain parameters and the adaptability, and finally the genetic algorithm was used to search for the optimal parameter combinations. The study shows that the parameter that has the greatest influence on the adaptability of the pipe curtain is the diameter of the steel pipe, followed by the clear distance of the steel pipe, and finally the thickness of the steel pipe. Considering the safety, water resistance and economy, the recommended design parameters of the locking pipe curtain are the steel pipe diameter of 990 mm, the steel pipe thickness of 20 mm, and the steel pipe clearance of 160 mm.

To study the effectiveness and impact of rail transit development in developing countries and to improve urban development experiences based on the TransitOriented Development (TOD) model, this study takes the Addis Ababa Light Rail Transit (LRT) as a case study to analyze its effects on residents' commuting and the spatial distribution of jobs and residences after its completion. Based on official city maps, resident questionnaires, and interview data, a multiple linear regression model was employed to analyze the influence of different commuting methods on commuting time. The findings indicate that the light rail system has a limited effect on improving residents' commuting efficiency. Further GIS spatial analysis reveals that the overall distribution of residential and employment areas in the city is uneven, with suburban residential density being exceeding five times that of urban areas. The analysis results reflect that the failure to coordinate land use with the development of the light rail corridor is a primary reason for the low commuting efficiency. The conclusions advance the understanding of the adaptability and implementation strategies of the TransitOriented Development (TOD) model in countries with lowdensity sprawl and relatively underdeveloped economies.

The Virtual track train (VTT) has been put into commercial operation as a new type of urban rail transport in China in recent years. To further understand VTT's operational performance, it is essential to develop a specific driving simulation platform to simulate VTT's unique hybrid autonomous/manual driving mode. The main contributions of this paper are as follows: First, a vehicle system dynamics (VSD) model of VTT was established using SIMPACK. Additionally, the control module for simulating the hybrid autonomous/manual driving mode of VTT was developed based on model predictive control and Logitech driving simulation hardware. Furthermore, a driving scene visualization interface was established using Unreal Engine and Blender to simulate the real driving environment. These components form a comprehensive simulation platform for the VTT. Simulation results demonstrate that the developed platform can effectively and accurately simulate the operational performance of the VTT under various driving modes, highlighting its significant engineering value.

To improve the inspection level of Beijing Subway interval facilities, and achieve cost reduction and efficiency improvement, the inspection basis of interval facilities was clarified based on the national standard, industry method, local standard and enterprise standard. The automatic inspection equipment and way of inspection of Beijing Mass Transit Railway Operation Corp. Ltd. were discussed. The functional parameters, advantages and disadvantages of typical comprehensive inspection equipment were compared and analyzed. The comprehensive inspection mode of Beijing Subway interval facilities was presented. The results indicate that the enterprise standard can cover the inspection contents and inspection cycles in the national standard, industry method and local standard. The comprehensive detection vehicle is suitable for dynamic inspection, while the comprehensive detection car is suitable for static inspection, both of which are far superior to the handheld equipment. The onboard detection equipment is mainly used for routine inspection. The comprehensive detection vehicle and the comprehensive detection cars combined with the existing professional detection equipment are mainly used for scheduled inspection. The fixed monitoring system and the handheld equipment are mainly used for special inspection. The comprehensive inspection should be implemented by leasing service in the short term, and by purchasing equipment in the long term. This study can serve as a reference for promoting intelligent operation and maintenance of urban rail transit infrastructure.

During longterm operation, the cooling system's heatsink intake can become clogged with environmental impurities and dust, reducing cooling airflow and affecting thermal dissipation efficiency. This can lead to overheating faults in the power converter, significantly reducing its operational reliability. To address the issue of dust blockage in the aircooled system, which can cause overheating faults in rail transit power converters, a realtime online monitoring method for the cooling system's thermal dissipation state is proposed. This method uses the thermal resistance of the heatsink, extracted from the power device and heatsink cooling curves, as a characteristic parameter. The GaussNewton iterative method is employed to extract these parameters, which are used to identify the degree of blockage and achieve online monitoring of the cooling system's thermal dissipation state. Simulation and experimental results validate that the proposed method effectively monitors the cooling system's operational state, demonstrating superior detection efficiency and effectiveness compared to traditional blockage detection methods.

Redundancy is a crucial component of network resilience. To address the current gap in time redundancy consideration when identifying critical stations in rail transit networks, this study proposes a comprehensive approach. First, we develop a timeweighted rail transit network model incorporating Space L and multiline coupling, which accounts for interstation transfer times. Second, we employ node deletion to simulate station disruptions and introduce three metrics: station redundancy index, network redundancy index, and a redundancy evaluation model based on shortest travel time variations. Using the 2024 Chongqing rail transit network as a case study, we compare the results between redundancybased and betweennessbased evaluations. The analysis reveals an average station redundancy index of 0.7998, with 3.87% of stations showing a Kmeans clustering center of 0.2788, indicating lower redundancy at critical locations. Redundancycritical stations are predominantly located near the network periphery along extended lines, while betweennesscritical stations are typically found at multiline interchange points, demonstrating distinct spatial patterns between these two categories. Network performance is more significantly impacted by disruptions at redundancycritical stations compared to betweennesscritical stations, validating the effectiveness of our identification method. This approach provides valuable insights for enhancing the resilience of urban rail transit networks.

Traction current return system is an important part of traction power supply system. System failures can damage primary and secondary equipment and potentially disrupt train operations. At present, there is limited research on realtime measurement of traction return current distribution for 25 kV AC power supply system subway. This study presents a synchronous testing methodology for measuring current in individual return cables to study return current distribution patterns and verify limitations in SCADA system monitoring. Based on return paths, the current is divided into three groups: station return, parking lot return, and ground return. The study analyzes the proportion and variation pattern of return current in different paths and compared findings with SCADA return current data. Results indicated that despite significant temporal fluctuations in return current magnitude, the distribution ratio remains stable most of the time, with only occasional variations. The average distribution ratios across different time periods vary by less than 1%. However, the SCADA system fails to accurately reflect return current changes. This research establishes return current distribution ratios through empirical testing, providing reference values for similar substations and directions for improving SCADA system monitoring capabilities.