The optimization of slow traffic systems in urban rail transit stations improves the operational efficiency of rail transit, upgrades the spatial quality of stations, and promotes the integration of stations and cities. To provide a reference for planning theories and practical research in this field in China, based on the literature related to slow traffic systems in urban rail transit station areas in WoS and CNKI core databases, and with the aid of CiteSpace, a literature analysis tool, this paper outlines the temporal, national, disciplinary, and journal distributions, analyzes the historical development of research and identifies recent hotspots: synergy research of stations and cities, shared bicycle transfer research, and accessibility research. In addition, the current progress in four key research directions is reviewed: slow traffic accessibility, slow traffic environment, slow traffic transfer, and slow traffic facility planning. Moreover, this paper proposes future research directions that can be expanded in terms of research object, method, and scope.

To explore the stress and deformation characteristics of an existing tunnel caused by foundation pit dewatering, a threedimensional numerical model was established based on an actual project. Taking the maximum vertical displacement of the tunnel as the evaluation index, an orthogonal table is used to screen the optimal combination and the main influencing factors. Then, the main influencing factors are analyzed via univariate analysis to study the stress and deformation law of the tunnel. The results of the range and variance analyses showed that the insertion depth of the diaphragm wall was the main factor affecting the maximum vertical displacement of the tunnel outside the pit. Therefore, when a new foundation pit project adjacent to an existing tunnel has a dewatering demand, this factor can be selected first to control tunnel deformation. As the insertion depth of the diaphragm wall increases, the bending moment and deformation of the tunnel decrease. After the insertion depth of the diaphragm wall reaches a soil layer with poor water permeability, the tunnel deformation decreases significantly. At this time, the deformation of the tunnel can be effectively controlled; however, controlling the deformation of the tunnel by increasing the insertion depth is of little significance. The dewatering causes the adjacent tunnel outside the pit to produce "horizontal duck egg" settlement deformation toward the pit, obliquely downward, and the deformation of the tunnel vault and the side arch waist of the adjacent foundation pit should be emphasized during the construction process.

To address the problems of “insufficient maintenance” and “excessive maintenance" in existing maintenance modes, a health status grading evaluation method for subway power supply equipment that considers the importance of indicators is proposed. First, the equipment health value was solved according to a combination of an analytic hierarchy process and fuzzy statistics. The importance of the index was considered, and the health status of the equipment was graded. Finally, a drytype transformer was considered for analysis. The results show that the obtained results can reasonably characterize the health status of the subway power supply equipment, which is consistent with the actual situation, and verify the accuracy and feasibility of the method.

In response to the relevant issues of urban operation transformation of existing railways under the background of "four network integration," this paper investigates new ideas and models for urban operation transformation of existing railways, taking the Xi'anHuyi railway transformation as an example. First, based on the function of urban railways, this study assessed the construction models and operational characteristics of existing railways for operating urban trains and identified current problems, such as incomplete technical standards, a low degree of network integration, a low passenger flow intensity, and significant operational losses. Second, taking the operation of urban trains on the Xi'anHuyi railway as an example, this study analyzed the transportation organization mode, passenger flow characteristics, and transportation connection methods and explored the applicability of the mixed passenger and freight modes of singletrack urban railways. Finally, this paper proposes optimization strategies for the highquality development of urban railways, including coordinating preliminary planning, optimizing transportation connections, improving operational efficiency, accelerating land development, and overcoming management barriers. These suggestions can provide a reference for subsequent renovation and upgrading of existing railways.

To address uncertainties in future operational carbon emissions and carbon reduction targets for urban rail transit networks, this study analyzes operational energy consumption data for the Xi'an urban rail transit system from 2018 to 2022. The carbon emission factor method is employed to calculate operational carbon emissions for the past five years. The index method is then used to predict energy consumption and carbon emissions for the next five years. Based on the binding energy intensity requirements outlined in China's Action Plan for Green Urban Rail Development, we quantitatively analyze the total energy saving target for Xi'an's urban rail transit operations over the next five years. Subsequently, the total carbon emission constraint and carbon reduction target are determined. The research results indicate that approximately 175.9×10⁴ tCO2e of total carbon emissions were generated during the operation of the Xi'an urban rail transit system from 2018 to 2022. Under these conditions, it is expected that approximately 321.6×10⁴ tCO2e of total carbon emissions will be generated over the next five years of operations, with traction and station power consumption being the main sources of carbon emissions. If the comprehensive energy intensity reduction target proposed by the association is achieved, compared with the predicted carbon emissions, the carbon emissions of the entire network are expected to reduce by approximately 13% by 2025; the carbon emissions of the entire network are expected to reduce by approximately 15% by 2027; and in total, carbon emissions are expected to reduce by approximately 10% over the next five years.

To explore the influence of a cavity on a shield tunnel, a refined numerical model of a shield tunnel, considering ring and longitudinal joints, is established. The variation law of the internal force, deformation, and section safety factor of the segment are investigated under various conditions, such as the depth, area, and location of the cavity. Additionally, the influence of different assembly points of the segment on a tunnel with a cavity behind it is discussed. The results indicate that the order of the adverse effects of cavities at different positions behind the tunnel on structural safety is tunnel waist > tunnel bottom > tunnel top. When the cavity area is 5.0 m², with an increase in the cavity depth, the bending moment and safety factor of the tunnel section at the center of the tunnel top or bottom cavity first decrease and then increase in the opposite direction, and the ellipticity of the segment first decreases to 0 and then increases in the opposite direction. The bending moment is reversed when the cavity depth was 0.3 m or 0.2 m. The safety factor of the section at the center of the left tunnel waist cavity decreases continuously, and the ellipticity of the duct piece and the bending moment increase significantly. When the cavity depth is 0.5 m, the bending moment of the tunnel section at the center of the cavity at the top or bottom of the tunnel is reversed when the cavity area is 3.75 m². The existence of circumferential joints within the cavity reduces the internal force of the tunnel section at the center of the cavity and improves its safety factor. However, its maximum joint opening is 2.03.5 times that of a cavity without a joint. The results provide a reference for the safety evaluation of the cavity behind the lining of a shield tunnel and the selection of assembly points.

Considering the drawbacks of inconsistent building information modeling (BIM) methods and nonstandard information in rail transit engineering, it is difficult to effectively and uniformly use BIM model data. Therefore, the Industry Foundation Classes (IFC)based BIM component standard library for rail transit engineering was studied. First, the component types, IFC expression of component information, and IFCbased extensibility mechanisms were studied according to the expression requirements of rail transit engineering components. Second, the technology framework of the BIM component standard library for rail transit engineering was proposed, including basic, technical, application, and user layers. Third, the classification and code method in the national standard was used to define the classification and code of these BIM components, and a component information template was proposed to define the component properties and their resource links. Finally, encryption and decryption methods for the BIM component model were applied to ensure the security of the BIM model data. The results showed that the proposed unified BIM component library enabled project participants to use standardized BIM component models to create a project model for rail transit engineering, ensuring the standardization of BIM models.

Aiming at the optimization problem of lasttrain connection planning in urban rail transit networks, which often brings difficulties in successful transfers, this study selects the arrival times of the last trains as decision variables and constructs a mixedinteger linear programming model to minimize the number of failed passenger transfers. To address the high model complexity caused by the expansion of the network scale, a quantum computing method is adopted to solve the proposed model. First, the original model is reconstructed into a twostage problem with a smaller computation scale. Then, the firststage optimization model is transformed into a quadratic unconstrained binary optimization (QUBO) model that can run on a quantum computer. Algorithm development and experimental testing are conducted based on the optical quantum computing technology of the coherent Ising machine. To verify the effectiveness of the proposed method, we consider the Beijing subway network as an example. The quantum computing results are compared with those from commercial solvers, confirming the feasibility of both the model transformation method and the quantum computing approach proposed in this study. These findings provide technical support for the further application of quantum computing in solving complex optimization problems in rail transit.

Subway traction energy consumption can be reduced by optimizing subway timetables. To solve the problem of the impact of passenger flow fluctuations and train delays on the actual energysaving rate, this study proposes a Dueling Deep Q Network (DQN) deep reinforcement learning timetable optimization algorithm combined with a realtime subway power supply current flow calculation model. An interval iterative optimization model based on the spatiotemporal distribution of the dynamic passenger flow was established to suppress the impact of passenger flow variation. The Adaptive Moment Estimation (Adam) and root mean square propagation (RMSProp) methods were applied to predict the Qnetwork and target Qnetwork as well as improve the convergence speed of the model. While minimizing passenger transfer, waiting, and total travel times, this model allows for the seamless switching of energysaving timetables. The test results for Suzhou Line 4 demonstrate the effectiveness of the proposed method. Under the conditions that the arrival time deviation at transfer stations was less than 2 s and the overall operating time of trains remained unchanged, the traction energy saving was 5.27%, and the train kilometer energy consumption decreased by 4.99%.

This study proposes a solution involving the use of a longitudinally induced ventilation system to solve ventilation challenges in factory buildings within a covered metro vehicle base, where natural ventilation is impractical and traditional horizontal ventilation systems are difficult to implement. We first created a threedimensional model for the longitudinally induced ventilation system, analyzed the impacts of the induced jet fan installation spacing and height on the airflow within the factory building based on numerical simulation results, and validated the proposed system against actual engineering conditions. The results indicate that the best overall and workstation ventilation effects can be achieved with installation spacings of 20 and 25 m, respectively, along with heights of 8 and 6 m, respectively, for the induced jet fans inside the factory building. The field tests agreed well with the simulation results. This study provides a theoretical basis for the application of longitudinal ventilation systems in engineering applications.