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.

This studyexplores the impact mechanism of population socioeconomic, land use, station characteristics, and other transportation attributes on rail transit passenger flow. Using multisource data including LandScan population grid, points of interest (POI), and automatic fare collection system (AFC), a spatiotemporal geographic weighted regression, gradient boosting regression tree, Shapley addition explanatory (GTWRGBRTSHAP) model, was developed to analyze the spatiotemporal heterogeneity and nonlinear effects of the these factors. A case study was conducted using data from Tianjin rail transit network, and the results showed that the mixed model effectively captures the spatiotemporal heterogeneity and nonlinearity between influencing factors and passenger flow. Factors such as population density, officetype land, shopping and leisure land, and betweenness have significant spatiotemporal differences in their impact of passenger flow. Factors such as residentialtype land, transportation facility land, land use entropy, and betweenness have significant complex nonlinear and threshold relationships with passenger flow. The above results provide strategic references and theoretical support for optimizing public transportationoriented urban development (TOD) planning and improving the efficiency of rail transit passenger flow.

Traditional fiber optic sensing methods mainly focus on onedimensional or twodimensional displacement monitoring of tunnel segments, making it difficult to effectively monitor threedimensional deformation between segment rings. This paper proposes a diamondshaped layout scheme based on distributed fiber optics, establishing a threedimensional deformation monitoring method suitable for shield tunnel segments. By analyzing the threedimensional deformation patterns of tunnel segments, three methods for calculating segment displacement are introduced. To validate the effectiveness of these methods, a simple and operable experimental device simulating threedimensional deformation of tunnel segments was designed, and indoor tests were conducted. The test results were compared with theoretical calculations, confirming the effectiveness of the proposed diamondshaped fiber optic layout for segment deformation monitoring, as well as the rationality of the three displacement calculation methods. The results demonstrate that the diamondshaped distributed fiber optic sensors, combined with the Kvalue decomposition method, provide optimal monitoring performance for segment displacement. The implementation of Brillouin Optical Time Domain Analysis (BOTDA) technology enables extensive realtime monitoring of tunnel segment displacement variations.

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.

To address the mismatch between urban rail transit construction and ridership efficiency in China, it is crucial to understand and master the influence laws of network ridership and improve efficiency. However, due to a lack of longitudinal data, research on the relationships between socioeconomic factors, network structure, and ridership remains insufficient. This study uses annual panel data from 2012 to 2020, calculates topological characteristics of the urban rail transit station network, and establishes a time fixedeffects model. The goal is to explore the topology of the urban rail transit network and its coupling relationship with urban layout effects on ridership changes, facilitating rational use of transit resources and improving core competitiveness. The results indicate that as the urban rail transit network develops, the complexity of the transportation network structure increases, and the number of interchange hubs rises, playing a crucial role in network connectivity. Changes in the topological variables of the urban rail transit network significantly enhance passenger flow; the densification of network distribution and regionalization of hubs help improve interchange connections and attract more passengers. The degree of coupling coordination significantly affects passenger flow changes; thus, the coupling relationship between population distribution and line layout should be considered according to local conditions in rail line network planning. Finally, this paper proposes relevant policy suggestions for rail transit network construction planning to provide a theoretical basis for urban rail transportation construction policy formulation.

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.

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.

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 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.

Guided by the need to address the shortcomings of subjective selection and the mismatch between capacity and demand in the selection of existing medium and low capacity urban rail transit standards, the standardized and procedural decisionmaking system for standard selection is developed. Firstly, the 4 criterion and 16 index evaluation system is established, considering constraints such as peak hour passenger flow, minimum transport capacity reserve, and the number of train operations. A multiobjective optimization model is constructed to determine the set of candidate rail transit systems. Besides, the CRITICTOPSIS algorithm is constructed to determine the weight coefficient values of each indicator and the optimal solution distance, thereby determining the optimal track system. Finally, using the Sline as the background for example verification, 5 alternative track systems are evaluated through a quantitative model. The CRITIC and TOPSIS algorithms were implemented using Python software. The decision values of rail transportation system rank in the order of selfguided monorail, crossseat monorail, light rail, guideway rubber wheel and low and mediumspeed magnetic levitation, indicating that the optimal rail system for line S is the selfguided monorail. Analyzing the standardized scoring matrix and index weight values of each type of rail system, the research results show that the model and algorithm proposed in this paper can effectively solve the problem of low and mediumcapacity rail transportation system selection.