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.

Surface defect detection technology plays an essential role in railway inspections by effectively preventing railway accidents and ensuring operational safety. This study addresses the issues of poor detection accuracy and low sensitivity to small targets in existing railway defect detection technologies. For the mask regionbased convolutional neural network (Mask RCNN) algorithm model, a model improvement scheme was proposed by incorporating an attention mechanism. This scheme introduces a Channelwise Spatial Module (CSM) into the feature extraction network for segmentation defect detection, effectively eliminating interference, obtaining multiscale feature representations, and acquiring more spatial and shallow information, thereby enhancing the edge detection capability for surface defects on railway tracks. In the same experimental environment, compared with the Mask RCNN algorithm, after adding the CSM, the mAP value of the Mask RCNN model increased by 6.5%. Among them, the AP values for the recognition of "depression,” “crack,” and “fatigue wear" defects on railway tracks increased by 6.3%, 6.9%, and 6.1%, respectively. The horizontal segmentation effects of the three defects improved by 11.6%, 12.5%, and 12.9%, respectively, compared with the Faster RCNN model, and the segmentation effects of the three defects enhanced by 8.8%, 10.0%, and 10.3%, respectively. This study demonstrates that the Mask RCNN model with CSM can better recognize three types of defects, enhance the detection accuracy and sensitivity to small targets, provide more secure and robust technical support, and guarantee intelligent track inspection.

Subway carriages are ventilated from the outside world through fans, which regulate the temperature, humidity, and wind speed of the internal environment of the carriages, improve air quality, and enhance the thermal comfort of passengers. Due to the limited number of applicable thermal comfort evaluation indices, accurately determining the thermal comfort of subway car occupants in transient environments is challenging. This paper first focuses on occupants of a Btype subway compartment as the research subject and proposes the joint application of DRBerkeley thermal comfort evaluation indexes by considering both airflow comfort and heat sensation. The study then employs the Stolwijk physiological model of human thermal regulation to construct a threedimensional model of the amplitudeflow fan and an overall simulation model of the subway compartment. Finally, using CFD software, STARCCM+, the study analyzes the effects of different fan speeds, fan hood disturbance speeds, and fan air supply temperatures on the microenvironment and thermal comfort of the occupants under seven different conditions during the summer. The results show that the DRBerkeley thermal comfort evaluation indexes can reasonably evaluate the thermal comfort of subway compartments under the premise of meeting the airflow comfort in summer; increasing the fan speed, reducing the hood disturbance speed, and reducing the fan air supply temperature can improve the thermal comfort of the occupants; in the seven working conditions, the fan speed of 1,400 rpm, the hood disturbance speed of 3.25 rpm, and the air supply temperature of 20°C have a uniform temperature and speed distribution in the compartments. The temperature and velocity distributions in the cabin were uniform, the occupant microenvironmental heat flow field was optimal, and thermal comfort was 0.766. This method can solve the occupant thermal comfort problem more comprehensively, which is of some reference significance for optimizing the thermal flow field environment in subway compartments and upgrading occupant thermal comfort.

With the rapid pace of urban development, the speed of urban rail transit systems in various cities is gradually increasing. The transitoriented development (TOD) model, which focuses on the comprehensive development centered around public rail facilities, has been widely adopted. This has led to a rise in the number of transfer stations and integrated transport hubs. The TOD approach in domestic rail transit is becoming more diverse, and the integration of station cities helps rail transit TOD reach new levels. Largescale rail transit TOD projects generally require planning in the early stages of the project based on advanced planning and coordinated design methods, which are more conducive to the implementation of the main body to create a comprehensive transportation hub project with core characteristics in the area. This study focuses on the mismatch between the core development area of Dongguan and the timing of rail transit construction there. It summarizes the practical path from early planning to implementation based on line networks and detailed planning research and innovatively proposes the construction of public rail facility coconstruction engineering. Advanced planning, coordinated design, and integrated construction models have introduced new design concepts. The research results indicate that the construction of public rail facilities according to the underground space model has solved the problem of urban, comprehensive hub locations being unable to be developed synchronously because of their inability to initiate and implement rail transit projects, provides new research directions for subsequent project development, design, and implementation, and provides successful cases for government decisionmaking.

To demonstrate the necessity and rationality of interconnecting Chongqing rail transit lines between core hubs based on the concept of urban rail transit interconnection, this study summarizes the macro positioning of planning fit, improving service quality, guiding urban development, and implementing resourcesharing using the example of Chongqing rail transit lines 26 and 27. It also analyzes the economic benefits, operating losses, and civil investment increases caused by the interconnection mode. With the effect of the time value, the converted net present was used as the measurement index of the necessity and rationality of the interconnection to exhibit rail transit lines 26 and 27 between the core hubs. The results demonstrate that the converted net present value of the interconnection with Chongqing rail transit lines 26 and 27 between the core hubs is greater than zero. The necessity for interconnection is significant, and the scheme is reasonable and should be recommended. Considering the necessity of urban rail transit interconnections, this study proposes an analytical framework that combines qualitative and quantitative analyses, enhances the research system of urban rail transit interconnections, and provides an effective reference for the planning and design of similar projects.

As property development above vehicle depots becomes increasingly common, it's crucial to address the construction and operational challenges this poses to the underlying facilities. This necessitates adaptive adjustments and optimizations in various aspects of depot design, including overall layout, fire safety, traffic management, utility systems, and vibration and noise mitigation. By comparing developed and undeveloped vehicle depots, this study proposes an optimization strategy centered on "one core concept and two principles." This approach aims to create favorable conditions for aboveground development while safeguarding the underground facilities' safety and environment, without compromising the depot's scale and functionality. The study outlines optimization strategies across multiple areas, including site selection, layout planning, maintenance procedures, emergency evacuation, ventilation and smoke control, and traffic flow. Specific recommendations include improving stationsection relationships, maximizing land use efficiency, implementing advanced maintenance equipment, and enhancing evacuation and smoke management systems. The ultimate goal is to minimize the negative impacts of aboveground development, fostering a harmonious relationship between the aboveground and underground facilities for mutual benefit.

To address the issue of incompatibility between the China Train Control System (CTCS) system used in mainline and intercity railways and the Communication Based Train Control (CBTC system) used in urban rail transit, which hinders the integration of the four networks and reduces the overall transportation efficiency of the rail transit system, research is conducted on main technologies such as onboard equipment, ground equipment, overlapping area design, and system switching process that support the integration of the four networks in the train control system. First, key technologies for integrated onboard equipment were proposed, including automatic train protection technology, automatic train operation technology, humanmachine interface technology, and train interface technology. Second, key technologies for ground equipment in overlapping management areas that support crossline operation of trains were presented, and the overlapping management area design technology that supports safe and smooth switching of train control systems without stopping was provided. Lastly, the system switching process of trains switching from CTCS to CBTC and from CBTC to CTCS without stopping in the overlapping area was explained. The research results suggest that crossline operation can be achieved by integrating onboard equipment that is compatible with ground equipment, reducing the number of ground equipment, simplifying the system structure, and enhancing system safety, reliability, and maintainability while also offering cost advantages. Adopting integrated onboard equipment with a simple system structure, low equipment cost, and minimal space requirements for installation is the future direction of technological development. The key technologies of the train control system compatible with CTCS and CBTC proposed can be used to guide system design, research and development, and application, which has guiding significance for achieving "four network integration."

The design standards for the roadbed structure of the metro depot have not been clearly defined in the Metro design specification (2013)," and the current practice of using the main line standard results in high and unreasonable costs. This study relies on the Zhengzhou Metro Tieluxi Depot project to conduct a numerical simulation analysis of dynamic loads under different subgrade structures and to study the variation law of the dynamic load distribution. The dynamic load generated by the ballastless track at the same train speed was smaller than that generated by the ballasted track. An increase in the thickness of the subgrade surface layer has a more substantial impact on reducing the dynamic load generated by the train operation. However, an excessively thick foundation increases roadbed stiffness, which is not conducive to stress dissipation. Hence, when the foundation thickness increases to a certain extent, the effect of reducing the dynamic loads gradually becomes less significant. The numerical simulation results show that the design scheme of the metro depot subgrade can appropriately adjust the parameters on the basis of "0.3 m+0.9 m" and "0.4 m+0.7 m", ensuring that the dynamic and static stress ratio of the subgrade is strictly less than 0.2, attaining the best level of safety and economy.

To address these challenges, a pragmatic design approach for the subway track panel and the substantial opening in the panel significantly reduces plate stiffness. Under construction conditions, traditional twodimensional frame section calculations fail to meet design requirements and realworld conditions. Drawing from a specific case involving the design of a stacked subway track panel in the highwaterpressure fine particle strata east of Beijing, this paper introduces the project's envelope and main structural design concepts. It examines critical structural calculation issues, consolidates design insights, and outlines operational conditions. The study yields a practical design scheme, offering valuable insights for future subway track panel designs during construction processes.

Intercity railways in the GuangdongHong KongMacao Greater Bay Area (GBA) face operational challenges when used for public transit. These challenges include unclear functional specialization, misalignment with urban development plans, and insufficient network operation, leading to low service efficiency. This study proposes a reorganization strategy informed by successful regional rail transit practices globally. The strategy focuses on three key areas: (1) Reorganizing intercity railways, urban express lines, and other rail lines based on distinct functional levels for optimized service allocation. (2) Optimizing the network layout based on urban travel demand characteristics. This includes optimizing external corridors, strengthening fast and direct connections within the core area, and further strengthening urban rail interconnection through station wiring and connecting lines. (3) Optimizing intercity station and transfer services to improve passenger experience. Implementing these strategies is expected to provide valuable insights for improving operational service levels and promoting the sustainable development of intercity railways in the GBA.