With the rapid development of urban rail transit, the subway, as an important public transportation, provides an efficient largescale travel option. Previous studies generally believe that the built environment around subway stations affects the passenger flow, but the size of PCA (Pedestrian Catchment Area) has not yet been unified. The purpose of this study was to verify whether the size of PCA affects the outcome value of the correlation study between metro ridership and the built environment. Taking 25 stations of Nanning Metro Line 1 as an example, five indicators were selected as independent variables, including residential population, jobs and commercial facilities, and the actual passenger volume of the stations was used as the dependent variable. The OLS regression model was used to compare the results of model fitting and influencing factor analysis under different PCA radius variables. There were differences in the research results of the relationship between passenger flow and built environment in the data collection of PCA in subway stations within different catchment areas. For Nanning, the radius of the PCA is 600 m, and the fitting of the correlation model between subway passenger flow and built environment is better than that of 300 m and 900 m. The scope of PCA will lead to inconsistency in the results of the study on the association between subway passenger flow and the built environment. In the future, it is necessary to conduct model analysis for different PCA radii and determine the appropriate PCA scale according to the fitting effect to improve the accuracy of the research.

By the end of 2024, a total of 28 provinces and 58 cities in Chinese mainland have opened 362 urban rail transit lines, covering a total length of 12,168.77 km, including 9,281.37 km of subway lines, accounting for 76.27%. By the end of the statistical period, 1,486.01 km of Fully Automated Operation (FAO) lines have been opened, representing 12.21% of the total length of operational lines. In 2024, 51 new urban rail transit lines (sections) were added, with a total length of 953.04 km, including 738.26 km of new metro lines and 425.70 km of new FAO lines, all of which were classified as GoA4. It is expected that by the end of the 14th FiveYear Plan period, the total operating scale of urban rail transit in mainland China will exceed 13,200 km. It is estimated that the annual passenger volume at the end of the 14th FiveYear Plan period will double compared to the end of the 13th FiveYear Plan period.

The traditional triple network integration evaluation system only considers the 'presence or absence' of rail connection facilities while ignoring the 'quality' of their operation. This limitation prevents proper evaluation of connection inconveniences caused by supplydemand mismatches and poor travel experiences. This study develops a comprehensive evaluation system for "railbusslow travel” integration by: retaining select indicators of “facility availability", introducing new indicators for "supplydemand matching” and “user experience”, as well as proposing key resource allocation methods across facility, network, and operational integration. The research results show that the optimized evaluation system effectively ensures convenience, comfort, and safety in rail connections. The findings provide valuable theoretical and practical references for systematically improving triple network integration in medium and large cities.

In response to the diversified and uneven demand for passenger travel, with the goal of improving service levels, this study proposes an operational mode for urban rail transit, which involves online flexible train composition and fulllength and shortturn routings, and integrates NSGAII algorithm to optimize the operational scheme. Firstly, the study analyzes the turnaround scenarios of trains under flexible composition conditions and determines the relationship between turnaround time and departure intervals. Secondly, using passenger travel costs and train operating kilometers as objective functions, a mathematical model for the operational mode of urban rail transit with online flexible train composition and fulllength and shortturn routings is designed based on the NSGAII algorithm. Finally, a case study is conducted to verify the feasibility and effectiveness of the algorithm for a specific rail transit line. The results show that compared to single routing, fulllength and shortturn routings, and mixed operation modes with multiple compositions, the proposed operational mode reduces vehicle operating kilometers by 42.68%, 22.81%, and 15.98% respectively, reduces vehicle utilization by 35%, 23.53%, and 16.13% respectively, and reduces the maximum load factor from 161.71%, 123.54%, and 135.49% to 119.68%. This operational mode effectively reduces vehicle operating kilometers and utilization while ensuring service levels and improving the balance of line load factor, thereby bringing greater benefits and improvements to urban rail transit systems.

To promote the quality and efficiency of inventory areas in metropolitans, urban renewal of transit station areas in cityn centers presents an urgent challenge. By incorporating the Quality dimension into the traditional NodePlace model to indicate the perception of spatial environment, this study constructs the NodePlaceQuality Rubik's Cube state model to assess the renewal potentialof transit station areas in the downtown. Using Tianjin's central area as a case study, the modeling results show that the proportion of dependent and imbalanced types of transit station area is as high as 35.49% and 38.71%, respectively, while balanced and coordinated types account for 22.58% and 3.22%, respectively. The transit station areas with high renewal potential are concentrated in the edge of the Inner Ring of Tianjin, and the renewal potential of transit station under construction is also relatively high, while the transit station areas with low renewal potential are agglomerated in the central business district (CBD). These findings provide theoretical support and policy insights for the urban renewal in the transit station area in the metropolitan's downtown.

As urban space becomes more complex through rail transit interconnectivity, this study investigates how to improve the spatial efficiency of metropolitan areas. Firstly, this article analyzes the research characteristics and shortcomings of synergy mode between interconnecting rail transit network and urban space through bibliometric methods. Secondly, by incorporating the concepts of networks and mobility into theoretical research and using multilevel network efficiency as the starting point, this study examines the key factors in synergistic development of network structure and function between rail transit and urban space. Based on this analysis, the Interconnection 2.0 model for synergistic development between rail transit and urban space is proposed, with the synergy relationship strengthened through network structure connectivity, network nodes, and element flow. Finally, combined with case analysis, this paper prospects the future development direction of interconnection at a higher stage in China. Theoretically, the study focuses on network hierarchy and nodality as well as the interaction between flows. In practice it provideds improves recommendations for improving the network connectivity and coupling of multilevel rail transit hubs. The research results provide a reference framework for the theory and practice of synergistic development between rail transit and urban space.

Addressing the compatibility issues of platform screen door (PSD) systems across different lines and vehicle types within the context of "fournetwork integration," this study innovatively proposes a design scheme for an adaptive PSD system, encompassing comprehensive solutions such as improving mechanical structures, optimizing control system algorithms, enhancing intelligence levels, and bolstering gap detection system capabilities. These solutions aim to elevate the flexibility and safety of PSD systems, thereby better accommodating the needs of diverse vehicle types and operational modes. By facilitating the adaptability to multiple vehicle types, they contribute to reducing station sizes and lowering construction costs for urban rail transit. This research provides valuable reference and insights for the upgrading of PSD systems under the backdrop of "fournetwork integration" in urban rail transit. By optimizing the design and functionality of PSD systems, it can effectively mitigate the impact of multiple vehicle types on PSD systems, further facilitating the smooth implementation of "fournetwork integration."

In response to the problems of unclear and insufficient connection paths and depth between urban rail transit industry planning environmental impact assessment (EIA), project EIA, environmental acceptance, law enforcement supervision, and regional ecological environment zoning control (zoning control), this study summarizes the characteristics and key contents of rail transit planning EIA and project EIA. Referring to the linkage requirements of rail transit planning EIA and project EIA, the connotation of listbased management is analyzed, and the feasibility of implementing listbased environmental management in the rail transit industry was analyzed. Lists for zoning control, planning EIA, project EIA, environmental acceptance, and law enforcement supervision are developed. The connection paths and methods for listbased environmental management in the rail transit industry are proposed. Research has shown that inventory management is an important measure for improving environmental management in the rail transit industry and has the conditions for implementation. The zoning control, planning EIA, project EIA, environmental protection acceptance, and law enforcement inspection checklists transmit different management requirements from front to back, while providing feedback on different management effectiveness information from back to front. Through different management lists, the approval department, planning department, construction unit, evaluation unit, and law enforcement department can identify key points that their respective departments and units should focus on, implement environmental access and environmental protection measure requirements, and provide technical paths and methods for promoting comprehensive environmental management of the rail transit industry.

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 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.