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.

To verify the effects of rail damping devices in the rail corrugation treatment for vibration reduction tracks, rail damping devices were added to a laddertype sleeper track and a steelspring floating slab track, respectively, in this study. The vibration and trackside noise characteristics of the two vibrationreduction tracks were reported, and the development of rail corrugation was tracked. The results show that the rail damping devices installed on the laddertype sleeper track can achieve positive effects in vibration and noise reduction in a wide band range, which can reduce rail vibration and trackside noise by 9.7 dB and 11 dB (A), respectively. The rail damping devices installed on the steelspring floating slab track can reduce rail vibration and trackside noise by 8.3 dB and 3 dB (A), respectively, within their operational frequency range. Longterm tracking tests revealed that the installation of rail damping devices can at least halve the rate of rail corrugation development on vibration reduction tracks.

To explore the impact of travelers' subjective spatial perceptions on travel behavior in the context of distinct urban terrain, this study takes Lanzhou, a typical rivervalleytype city, as an example. It establishes an integrated model of SEMLogit and explores the impact of the spatial perception of rivervalleytype city travelers on rail transit travel mode choice based on questionnaire data. The results show the following: ① Compared with the logit model without considering travel space perception, the goodness of fit of the logit model considering travel space perception by SEM increased by 0.234, and the prediction accuracy increased by 7.75%. ② The spatial perception of travelers in rivervalleytype cities has a significant positive impact on the choice of rail transit travel intention and behavior. ③ The spatial perception of travelers in the rivervalleytype city from five aspects, including the unnecessary detour, rivers in the river-valley-type city, wasp waist blockage, convenience of inter-group travel, and degree of being affected by road slope, l significantly influences travelers in the river-valley-type city to choose rail transit. The degree of influence decreases sequentially among these factors.

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.

To predict the vibration response of buildings along subway lines quickly and reasonably, a building structural system is decomposed into two parts, namely, a propagation structure and a response structure, based on the theory of mechanical mobility. The bearing structure is assumed to be a beam element model, and the slab structure is considered a plate element model. The mobility formula and the corresponding matrix expressions for each unit system are derived, and a traininduced structural vibration response model is constructed. The reliability and accuracy of the model are validated through onsite testing, showing that the predicted structural responses align well with measured vibrations in both time and frequency domains. In the frequency domain, the maximum error of the center frequencies of each 1/3 octave band does not exceed 5 dB, indicating that the proposed traininduced structural vibration response model can quickly and effectively predict the structural vibration response and that the outcomes can provide theoretical support for vibration prediction along subway lines.

This study examines the impact of shield tunneling excavation speed and slurry solidification time on the buoyancy of tunnel segments, focusing on the section between Tongyuan Road Station and Xinggang Street Station on Suzhou Metro Line 5. A threedimensional finite element model of shield tunnel segments was developed using Winkler elastic foundation beams, considering the dynamic and static buoyancy effects generated by synchronous and secondary grouting on the pipe segments. The analysis assessed how excavation speed and grouting solidification time influence the uplift and misalignment of the segments. Results showed that both uplift and misalignment increased with higher tunneling speeds. The upward floating problem mainly occurs at the bottom of the pipe segment in the nonsolidified section of the slurry, whereas the misalignment mainly occurs at the junction between the nonsolidified section and the shield tail section, as well as between the nonsolidified section and the solidified section of the slurry. To avoid floating and misalignment of the pipe segments from exceeding the specification requirements, the excavation speed of the shield machine should not exceed 10 rings per day. Furthermore, it was observed that as the solidification time of the slurry increased, the amount of floating and misalignment of the tunnel segments gradually increased. Therefore, the use of a fastsetting and early strength dual liquid slurry is beneficial for controlling the floating of shield tunnels.

In response to the increasing speed and strict requirements for bridge smoothness in the design of railelevated bridges, this study is based on the design of the elevated bridge of Beijing Metro Line 22 at a speed of 160 km/h. A new type of adjustable height device is developed and designed based on a lowmeltingpoint alloy as the height adjustment medium. A series of experimental studies are conducted, including the structural design of the device, indoor temperature and pressure tests, fullscale pressure adjustment performance tests of the compression shear machine, and onsite beam erection tests. The findings indicate that the new adjustable height device enables stepless bidirectional height adjustment with a rapid adjustment speed, completing height changes within 30 s. The device achieves millimeterlevel accuracy, and the alloy demonstrates excellent stepless adjustment performance and compression stability once cooled and solidified. The accuracy and stability of this adjustable height device not only ensure the smoothness of elevated bridge beams but also offer valuable guidance for engineering applications, such as replacing deteriorated bearings and adjusting for differential settlement in bridges.

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 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.

To address the challenges of high risk and extended construction periods associated with conventional methods for building longdistance connection channels, this study introduces a mechanical method in the composite formations of South China for the first time. Research focused on the overall project plan, selection of construction methods, equipment choices, and segment structure design, which led to the successful implementation of the project based on these findings. The following conclusions can be drawn: the mechanical method of connecting channels can solve engineering problems with long distances, large angles, and large inclinations and is applicable to composite formations in South China; it is feasible to change the assembly method of pipe segments from radial insertion to longitudinal insertion followed by radial insertion, by modifying the pipe segment design scheme.

To address issues related to the size effect of deep circular shaft excavation for rail transit, this study analyzes the stress and deformation characteristics of a circular excavation enclosure structure using the foundation pit project of the ShenzhenDaya Bay Intercity circular working shaft as a case study. The loadstructure method is employed to systematically examine these characteristics under various diameter conditions. The study compares the calculation results from both a 3D spatial structure model and a 2D elastic foundation beam model, discussing the impact of excavation size on the performance of the circular enclosure structure. The findings reveal that the circular diaphragm wall behaves as a quasicircular structure, generating a vertical bending moment due to soil and water pressure, which indicates a multidirectional stress state. It is feasible to utilize a simplified 2D equivalent model for designing a circularfoundation pitretaining structure, as its calculation results are more conservative than those of the 3D model. Furthermore, the spatial dimension significantly influences the performance of the circular enclosure structure, with noticeable circumferential effects observed when the diameter of the deep circular working shaft is less than 30 m.

This paper proposes a combined support system comprising retaining piles, tensioned anchor rods, and inclined anchor cables with grouting to solve the problems associated with constructing supporting structures for deep excavations near obstacles on one side. The study utilized Midas software for modeling, and singlefactor optimization analysis schemes were designed considering four aspects: spacing and diameter of tensioned anchor rods and number and length of segments for inclined tensioned anchor cables. The rationality of this scheme was validated using engineering examples. The results showed a match between the simulated trends of the horizontal and vertical displacements of the slopeprotection pile tops and the monitoring results. The vertical displacement exhibited a parabolic trend, and the horizontal displacement exhibited an arched shape. The maximum horizontal displacement of the pile tops decreased as the spacing of the tensioned anchor rods decreased and increased as their diameters and the number and length of segments of inclined tensioned anchor cables decreased. During construction, the deformation of subway ancillary structures was wellcontrolled and significantly less than that of the adjacent deep excavation. The top settlement showed a fluctuating upward trend, whereas the deep horizontal displacement had a middlehigh and endlow pattern at different excavation stages. As the excavation depth increased, the subway structures' maximum horizontal deformation shifted downward along the shaft wall.

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.

A vehicle speed measurement platform was developed to address the problem of diverse speed sensor models and an excessive number of sensors. This study outlines the overall design principles of the speed measurement platform, informed by an analysis of speed requirements for systems including vehicle traction, braking, signaling, and running gears. The proposed technical scheme advocates for the unification of speed sensors across various vehicle systems and introduces a method for calculating vehicle speed by integrating data from speed sensors and accelerometers. Additionally, it provides a technique for calculating the reference wheel diameter in conjunction with ground responder equipment information. The platform features two flexible methods for transmitting speed information: hardlines and networks. The research findings indicate that, compared to traditional speed measurement methods, this platform offers a unified and more accurate source of vehicle speed information, effectively meeting the requirements of traction, braking, signaling, and running gear systems.

Rail vehicles may experience abnormal vibrations, noise, and structural fatigue failure because of the unreasonable modal mismatch between an entire vehicle, equipment, and bogie. To investigate the modal parameters of bogies, experimental and simulation analyses were conducted. Initially, a modal identification method was employed, utilizing the running state environment as excitation. The crosscorrelation function of the structure's vibration response signal output was used to replace the frequency response function, in conjunction with the PolyMax modal identification method, to effectively identify modes that are easily excited during the structure's operation. Next, the effects of wheel turning and variations in vehicle load on the operating modes of the structure were examined to gain a comprehensive understanding of the bogie structure's modal parameters. Finally, a finite element simulation method was used to calculate the modal frequencies of the bogie structure in the free and constrained states. The results showed that wheel turning had little effect on the modal parameters of the structure. However, with increasing load, the modal frequencies at all orders generally increased. This was related to the increase in the air spring stiffness of the bogie owing to the increased vehicle load, even if the boundary constraint state of the structure changed. By comparing the test results with the simulation analysis results of the bogie structure in the free and constrained states, it was concluded that it is necessary to simulate the actual boundary constraint conditions as much as possible to ensure the accuracy of the finite element model. These findings can provide a reference for subsequent studies on modal mistuning designs.

In response to the problem of a relatively single smoke exhaust mode and low smoke exhaust efficiency in the public area of a subway station, this study considered the public area of a certain urban rail transit station concourse as an example to establish eight different smoke exhaust conditions, focusing on the smoke exhaust efficiency of opening smoke exhaust outlets at different positions. Through simulations, the relationships between visibility, temperature, and carbon monoxide (CO) concentration over time under different working conditions were obtained. The research results show that when a fire occurs in the public area of a subway station concourse, it is not better to open more smoke exhaust outlets but to determine according to the opening position of the smoke exhaust outlets. Opening the smoke exhaust outlet during the horizontal spread stage of smoke will interfere with the horizontal layered flow of smoke and intensify the heat and material exchange between the upper layer of smoke and the lower layer of cold air, resulting in a decrease in the height layer with a temperature of 60°C and a visibility of 10 m, which is not conducive to personnel evacuation; When the fire source is located at the most unfavorable point of the smoke exhaust system in the middle of the public area on the concourse level, the smoke exhaust outlet near the smoke barrier wall in the middle of the public area on the concourse level should be opened normally to smoothly discharge the accumulated fire smoke.

Considering the contradiction between construction intentions and financing conditions in China, this study employs a case study method to examine the investment and financing model of the London suburban railway. First, this paper outlines the general overview, operational process, and social and economic benefits of the Crossrail suburban railway line. Next, it analyzes and discusses the proportions and amounts of investment from central and local governments, as well as the contributions from various beneficiary entities within the “coinvestment by central and local governments+contributions by beneficiary entities” model. Finally, the investment and financing experience of Crossrail is summarized from the perspectives of central and local coownership, attracting social beneficiaries, TransitOriented Development (TOD)Integrated Development, and attracting other transportation enterprises. The results of this study can provide reference for the investment and financing of suburban railway and the entire urban rail transit industry in China.