To minimize disturbances to an existing metro station during shield tunneling in a waterrich soft stratum, this study focuses on the construction of a Ttype transfer station where shield tunneling passes through an operational station. The study examines the cutter configuration and tunneling parameters for shield tunneling through a diaphragm wall without glass fiber reinforcement using theoretical analysis and field measurements. Key risk control measures for shield tunneling through the operational station are also proposed. The results indicate that the shield can safely cut through the diaphragm wall by using highstrength shell cutters with varying heights, reducing the tunneling speed and shield thrust, and increasing the cutter head torque. Disturbances to the station floor can be reduced by considering the interaction force between the station floor and the surrounding stratum as an additional load during the underpass construction. Setting the chamber pressure at 1.2 times the static soil pressure at the shield's center further minimizes floor disturbance. Effective settlement control of the existing structure is achieved by filling the gap between the shield shell and the surrounding stratum with clay shock and using a combination of synchronous grouting, secondary grouting, and radial grouting to fill gaps behind the segments. The primary deformation caused by tunneling beneath the operational station is settlement, while shield cutting through the diaphragm wall leads mainly to horizontal displacement, accounting for over 75% of the total horizontal movement.

This study explores the applicability of oblique bolt joints in smalldiameter shield tunnel beam melting (TBM) tunnels, clarifying their mechanical properties and damage mechanisms. A segment structure with an external diameter of 6.2 m and a thickness of 350 mm was utilized as a prototype for conducting bending performance tests on steel fiber concrete segments with oblique bolted joints under four different horizontal axial force conditions. The analysis focused on the deformation characteristics and flexural performance of the segment joints across varying axial force levels, as well as the failure processes and mechanical properties under failure conditions. The results showed that the higher the axial force on the segment joints, the higher the joint stiffness, requiring larger bending moments to open the joint. In other words, the joint axial force can be actively increased by increasing the bolt preload or by applying annular prestressing to improve the joint stiffness. Compression of the sealing gasket under joint axial force results in stress concentrations within the sealing groove. Therefore, selecting an appropriate sealing gasket or optimizing the sealing groove structure is essential in the design process. The study also found that enhancing the compressive strength of the top concrete and reducing the insertion angle of the oblique bolt significantly improve joint bearing capacity. These findings provide valuable guidance for the design of segment joints.

In response to the problems of insufficient crosslevel, crossstandard, and crossregional integration in the development of multilevel rail transit in the Guangdong Hong Kong Macao Greater Bay Area, empirical analysis methods were used to study the deepseated influencing factors from the aspects of policy system design, planning and construction, and coordination of operating entities. On the basis of analyzing the current situation and existing problems of multilevel rail transit development in the Guangdong Hong Kong Macao Greater Bay Area, this paper explores the successes, failures, and lessons learned from the development of multilevel rail transit in urban agglomerations at home and abroad. It proposes countermeasures such as establishing an integrated integration system mechanism and policy norms, strengthening integrated planning and construction management, promoting the integration of comprehensive transportation hubs, improving land support policies and investment and financing supporting policies, and establishing a multilevel rail transit operation enterprise alliance in the Greater Bay Area. The research results can provide a reference for the decisionmaking of multilevel rail transit integration in the Guangdong Hong Kong Macao Greater Bay Area.

This paper addresses the problem of mismatch with the surrounding urban renewal when applying the TOD stationcity integrated development model to domestic rail transit stations. Based on the classic nodeplace (NP) model and the introduced nodeplaceridership (NPR) model with passenger flow, this study takes Xi'an Metro Line 3 as an example. Relying on spatiotemporal big data, passenger flow data within 24 hours for six consecutive months are selected to calculate the basic indicators of 26 stations, which are classified into six categories: placeahead and low ridership, deficient and low ridership, matching and midlow ridership, nodeahead and midhigh ridership, nodeahead and midlow ridership, and saturated nodeahead and high ridership. This results indicate that Xi'an Metro Line 3 has the characteristics of a relatively higher node value and a lower place value. Given the identification of the same characteristics across the six station types, we propose precise matching strategies for placeahead, coordinated, and ahead type stations. Specifically, placeahead stations should prioritize connection with other transportation modes and pedestrian accessibility, coordinated stations should optimize supporting facilities and explore the potential of place features on this basis, and ahead stations should integrate resources to form railway microcenters. These three processoriented transformation measures can be applied to other regions and contribute to improved station function and service.

Electropneumatic braking is the most common braking method adopted by most urban rail trains. However, the disadvantages of poor controllability and slow response of air brakes result in inaccurate parking and poor comfort. In addition, there are issues, such as greater losses. The solution to address these issues is to replace existing air braking with electric braking, which is an ideal solution. Based on the development history of full electric braking, this study elaborates on the current situation and the main problems that must be overcome in the application of full electric braking. From the perspectives of high and low speeds, this paper provides a detailed introduction to the difficulties in achieving full electric braking and their corresponding solutions. Each difficulty is analyzed and summarized, and future development directions are discussed.

To monitor rail health in realtime and provide early warning of rail fracture damage, this study proposes a broken rail detection method that combines ultrasonic guided wave detection and variational mode decomposition signal processing technologies. The system workflow and hardware circuits of each module were designed and constructed according to the requirements for rail fracture detection. A threedimensional rail model was created using finite element simulation software to analyze the propagation speed of ultrasonic guided waves within the rail and assess the feasibility of the noise reduction technique. The system's effectiveness was verified through equipment installation tests on Suzhou Metro Line 5, where artificially simulated rail fractures were used. The results demonstrated that, upon rail fracture, the system achieved a remote alarm time of 3 minutes and the defective positioning error is 1.1%, providing a reliable approach for rail fracture monitoring.

This study investigated the thermal environment and comfort in elevated subway stations in Wuhan, determined passenger thermal comfort ranges, and examined the impact of station architectural forms on passenger comfort during typical summer days at five representative stations. The research combined instrumental measurements with subjective surveys. Linear fits were applied to the standard effective temperature (SET*) and mean thermal sensation vote (MTS) at two stations, and these were compared with the predicted thermal sensation (PTS) to determine passengers' thermal sensation ranges. The results indicated that the stations tended to fail to meet the requirements of the "Code for design code (GB 501572013)". Additionally, indoor air temperatures were frequently too high, relative humidity largely met the standard, and air velocities in most stations were low. Survey data suggest that station design significantly affects passenger thermal comfort, revealing a preference for open platforms during summer. Moreover, the PTS curve remained consistently higher than the SET*MTS curve, indicating that passengers' summer thermal adaptations exceeded expectations. Finally, common shading, ventilation, and thermal environment improvement measures for regions with hot summers and cold winters were proposed alongside theoretical insights for enhancing thermal comfort and supporting green transitions in elevated subway stations in Wuhan.

When a shortcircuit fault occurs between the positive pole of a highvoltage DC circuit for a train and its carbody inside the station in a straddle seat monorail DC traction system, this causes the carbody grounding relay (GR) of all trains inside the station to actuate and the circuit breakers of the train to trip. Meanwhile, this also triggers multiple 64D grounding protection actions and trips the circuit breaker of the DC feeder. The fault results in a loss of power to the DC traction system. It is necessary to identify the faulty train and restore the normal power supply of the DC traction system as soon as possible to reduce the impact of the accident. First, the study analyzed characteristic differences in the amplitude of the grounding current and negative receiving electricity current for a faulty train compared to a normal train when a shortcircuit occurred between the positive circuit and the carbody based on the equivalence model of the DC traction bipolar power supply system for straddle monorail transportation. Second, an identification method for a faulty train is proposed based on a comparison of the grounding current and negative current amplitude. The identification procedure is activated when the grounding current exceeds a predetermined threshold. If the grounding current amplitude is greater than the negative current, the train is identified as faulty; otherwise, it is considered to be in a normal state. The accuracy and effectiveness of this method were validated through MATLAB simulations and field tests. The proposed approach is simple, practical, and highly reliable, providing a strong safeguard for the safe operation of straddleseat monorail systems.

To enhance the emergency response capability of subway waterlogging, this study investigated waterbarrier technologies and devices for subways, both domestically and internationally. A systematic review of conventional and innovative subway waterbarrier technologies and devices was conducted, focusing on subway waterlogging risk points such as station entrances/exits, vent shafts, main tracks, and vehicle depots. The advantages and disadvantages of various subway water barrier technologies and devices were analyzed. This study discusses the challenges faced by subway water barrier technologies and devices in terms of cost economy, intelligence, automation, and sustainability. Recommendations are provided for structural optimization, material improvement, multifunctional water barrier devices, intelligent and automated control, green technology, and sustainable development. The results indicate that different waterbarrier devices are suited to various application scenarios. Water barrier devices should be selected based on risk points and flood characteristics. Conventional subway water barrier devices are widely used and are technologically mature. Compared with these technologies, new technologies have advantages in terms of automation, resourcesaving, and improved emergency reliability. This study aims to serve as a reference for the design, installation, and application of subway waterbarrier devices, providing technical support for ensuring the safe operation of subway systems and essentially responding to subway waterlogging.

To address the issue of reduced comfort resulting from rapid aerodynamic pressure changes inside the tunnels used for urban rapid transit trains, a study was conducted on the effects of the tunnel diameter and pressurerelief schemes on incar pressure. First, pressure comfort standards were selected based on relevant regulations, and a finite element model was established, which included a train model, a tunnel model, and pressure relief measures at the tunnel entrance. Subsequently, the pressure variations inside and outside of a train were investigated for different tunnel diameters and airtightness indices. Finally, the impact of implementing buffering schemes at the tunnel entrance on the incar pressure was analyzed. The research results indicated that when the tunnel diameter increased from 6.0 m to 6.1 m, the maximum incar pressure variation decreased by approximately 4.2%, with further increases in tunnel diameter having a limited effect on reducing the pressure variation. When the airtightness index was ≤6 s, each additional second resulted in a 15–25% reduction in the maximum incar pressure variation. Additionally, when a fully enclosed sound barrier was installed at the tunnel entrance as a pressurerelief structure, the maximum incar pressure variation could be reduced by approximately 4050%. Measures can be taken to enhance the overall vehicle airtightness, such as improving the seals around the doors for the driver's cab and passenger cars, installing pressure protection valves at freshair inlets and exhaust outlets, and enhancing the seals on the vehicle body and intercarriage passageways.