In response to the maintenance needs of bridge bearing defects, existing bearing replacement methods all require jacking up the bridge to complete the bearing replacement, significantly impacting bridge structural safety and traffic operations. This study designs and manufactures a “lowmeltingpoint alloy bidirectional heightadjustable forcemeasuring bridge bearing, leveraging its bidirectional heightadjustable characteristics to develop a technology for replacing bridge bearings without jacking up the bridge. Against the backdrop of practical engineering applications, a comparison is made between the "bridge bearing replacement technology without jacking up the beams” and the existing “bridge bearing replacement technology with jacking up the beams." Utilizing this technology, bridge bearing replacement can be achieved without jacking up the superstructure, effectively avoiding stress changes in the bridge structure caused by jacking and enhancing maintenance efficiency and safety. Additionally, this technology is easy to operate, has minimal impact on traffic operations, and possesses broad applicability and promotional value.

An investigation into the current status of the smart operation and maintenance system for urban rail power substations has been conducted. The paper summarizes the challenges faced by the current comprehensive automation system scheduling and operation and maintenance methods of urban rail power substations, which are considered from aspects such as system architecture, hardware configuration, information conditions, dispatching mode, and operation and maintenance management. Requirements for the smart operation and maintenance system of urban rail power substations have been proposed. The overall framework of the smart operation and maintenance system for urban rail power substations has been designed; various independently constructed power supply subsystems have been integrated to form a unified dispatching and operation and maintenance platform, and the full life cycle data of equipment on both the power supply and distribution sides of the urban rail power supply system have been integrated. The smart operation and maintenance system for substations in the urban rail power supply field, which has been constructed, is applicable to the technical specifications of the urban rail cloud, addressing issues such as decentralized construction, inconsistent standards, and redundant investment in multiple subsystems and key equipment of the urban rail power supply system. It meets the current and future development needs of intelligent power supply systems.

The existing decentralized rectification scheme for direct current (DC) lighting systems in metro stations faces several challenges, including low power supply reliability and efficiency, high cable costs, significant distribution losses, and difficulties in unified equipment maintenance and power quality management. To address these issues, this paper proposes a centralized rectification scheme for metro station DC lighting systems. The study begins with an analysis of the system architecture, current status, and limitations of the existing decentralized scheme, followed by a detailed presentation of the proposed centralized solution, including its system architecture, DC power supply configuration, key components, and required system modifications. A comprehensive comparison between the two schemes is conducted using actual engineering data, focusing on system losses, costs, harmonic content, and operational reliability. The results demonstrate that compared to the decentralized scheme, the centralized rectification scheme requires less feeder cable usage and achieves lower system costs. It also shows significant improvements in reducing cable losses, increasing system power efficiency, and decreasing harmonic content. Furthermore, the power modules in the centralized scheme operate under more favorable conditions, leading to enhanced system stability. Based on these advantages, the centralized rectification scheme proves to be a more suitable solution for DC lighting systems in metro stations.

This paper analyzes the power supply system of suspended monorail transit and emphasizes the necessity of DC system ground fault protection to ensure equipment and personnel safety under various operating conditions. While conventional voltagebased ground fault protection devices can provide basic protection functions, they lack selective tripping capability and may expand the fault area. Based on Kirchhoff's current law, this paper proposes an innovative sectional currentbased ground fault protection scheme. Through the implementation of inverse timecurrent characteristics and differential current components, the scheme achieves accurate and rapid fault section identification, enabling priority tripping of corresponding sections to isolate faults, thus significantly improving system selectivity. Through analysis of protection objectives, coverage, types, and operation time limits of both 64D protection and frame current protection, the study concludes that these two protection methods are complementary and can operate simultaneously. Field applications demonstrate that all protection functions perform sensitively and reliably. By calculating key parameters for 64D protection, this paper proposes protection schemes and system setting values for practical engineering applications, optimizing protection system selectivity, effectively reducing fault ranges, and ensuring operational safety.

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.

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.

This paper addresses the challenges in onsite engineering acceptance testing of urban rail transit signaling systems in China, which currently face issues such as singlemethod approaches, lengthy cycle times, low efficiency, high costs, and heavy workloads. A method for automatic generation of onsite engineering acceptance test sequences is proposed. The methodology involves three main steps: First, analyzing the constraints of interconnection test case sets for urban rail signal systems; second, dividing the line into independent test sections; and third, converting line characteristics into computerrecognizable formal language to enhance editing efficiency and humancomputer interaction. The proposed method employs an “auxiliary generation tool" to automatically generate fieldexecutable engineering acceptance test sequences. The effectiveness of this approach is validated through tests on actual railway lines. Results demonstrate that test sequences designed using formal language meet engineering acceptance requirements, achieve 100% coverage of interconnection test cases, and significantly reduce field testing time while improving efficiency compared to traditional manual test sequence design methods.

The Beijing Northeastern Ring suburban railway renovation project aims to transform the line into a public transitstyle operation, with portions of the route cooperating on shared tracks with Subway Line 19. While enhancing passenger service, the line must preserve its critical function as a connector within the main railway network. The system design requires a maximum throughput of 20 train pairs per hour. The existing Changping Station, which serves as both a turnback station for the Northeastern Ring Line and a connection point to the vehicle depot, is characterized by its large scale and operational complexity, making it the bottleneck for system capacity. This station becomes the critical factor in determining whether the system's maximum capacity requirements can be achieved. The Northeastern Ring Line adopts the CTCS2 train control system with ATO and automatic turnaround capabilities. To enhance Changping Station's capacity and meet system requirements, modifications were implemented to the existing station layout and signaling system. The station tracks, throat areas at both ends, and connections to the main line were optimized. Combined with signaling improvements and verified through traction calculations and multiscenario timetabling, Changping Station ultimately achieved a throughput capacity of 23 train pairs per hour, not only satisfying system requirements but also providing a 15% capacity margin. Through comprehensive analysis of Changping Station's capacity, the study identified that the number of arrival and departure tracks, length of station throat areas, signal configuration, and operating speeds are the primary factors limiting station capacity. The paper proposes solutions for improving station throughput capacity, providing valuable reference for future suburban railway design projects.

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.

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.