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.

Public participation in lowcarbon travel is an effective way to reduce carbon emissions. How to further guide and incentivize public participation in lowcarbon rail transit through carbon inclusive mechanisms is an important research field for rail transit enterprises to carry out green and lowcarbon practices, this paper according to the national carbon peak, carbon neutral and carbon GSP policies, as well as the construction of carbon GSP policy system in Shenzhen; This paper focuses on the "Our LowCarbon Road" project, combines the mechanism of carbon GSP in Shenzhen and the characteristics of the urban rail transit industry, relying on the Internet technology and data aggregation platform to systematic analysis was conducted on the business model, methodology, business process, and data flow, the system architecture and technology program of Shenzhen's carbon GSP application platform, as well as the implementation and application significance of the platform, and puts forward the development ideas of expanding carbon application scenarios, innovating carbon financial products, and crossregional cooperation. This provides Shenzhen's experience for the application of carbon inclusive urban rail transit, which has practical value in tapping into the public's emission reduction potential, stimulating green travel for citizens, and feeding back the rail transit industry.

The maximum operating speed of urban rail expresses is 160 km/h. As the main technical parameters of the gauge in the current national standards do not cover this speed, this study uses theoretical analysis and dynamic simulation methods to research the gauge system and calculation methods. The calculation formulas in the Standard of Metro Gauges (CJJ 962003) were adjusted to be suitable for the 160km/h express project. The optimal structure gauges of the station, tunnel, and bridge were formulated in combination with the express project characteristics based on research on the basic gauge parameters. 1) Compared with the stopping condition, when the train passed the station at 100 km/h, the distance between the station platform and the central line of the track was 1,600 mm. 2) The size of the circular tunnel section was determined by the space requirement for equipment layout in the urban rail express project. When the flexible overhead contact system was used, the optimal tunnel diameter was 7.5 m (the gauge diameter was 7.2 m). When the rigid overhead contact system was used, the optimal tunnel diameter was 7.1 m (the gauge diameter was 6.8 m).

Current solutions for enhancing the efficiency of existing urban rail transit lines are limited. As a pioneering initiative, the concept of running express/local trains on these lines presents a versatile solution for Shighquality development scenarios. After systematically reviewing the methods for running express/local trains on existing lines, this paper introduces four distinct strategies tailored to the unique features and operational needs of different lines: employing extended intervals for rapid trains, implementing alternate stationskipping for accelerated service, utilizing malfunctioned train stop lines for express/local runs, and operating partialroute shuttles for express/local trains. Drawing from domestic and international case studies, this research delves into the operating principles, advantages, disadvantages, and operational requirements of the aforementioned methods. Additionally, the necessary modifications for implementing express/local train services on existing lines are discussed.

With the early opening of urban rail transit, Shanghai has been a forerunner in urban rail transit operatingline renovation in China. The experiences and lessons learned from Shanghai in operatingline renovations have reference value for other cities in China. First, the operatingline renovation process of the Shanghai urban rail transit was reviewed. Three main development trends indicate that the focus is on a gradual transition from individual conditions to overall conditions, that the renovation contents are gradually being diversified and systematized, and that the renovation demands that align with the development goals of the city and urban rail transit network are continuously deepening and expanding. Second, developing a renovation plan with systematic thinking, minimizing the impact on passengers while ensuring construction safety and quality during renovation, and active postevaluation after renovation are summarized as the key points in the operatingline renovation of Shanghai urban rail transit. The difficulties in operatingline renovation of Shanghai urban rail transit were analyzed in terms of limited financial support, highefficiency requirements for internal and external communication, challenges in project management, and insufficient technology. Important future works for operatingline renovations of Shanghai urban rail transit are discussed, including additional financing channels, research on improvement and innovation of construction plans and management mechanisms, deeper evaluation of the operational urban rail transit network, and the technology of nonclosure renovation of underground stations without prereserved conditions.

Under the major strategic deployment of a dualcarbon strategy, studying the whole lifecycle carbon emissions of rail transit and reasonably quantifying its carbon emission level is essential to achieve peak carbon and carbon neutrality in the transportation sector. Based on a new metro line in Beijing, this study analyzes the whole lifecycle carbon emissions of rail transit, establishes a carbon emission calculation model for the whole line and the whole lifecycle of rail transit, and quantitatively calculates the carbon emission of the whole line and the whole lifecycle of the new metro line. Carbon reduction measures in the construction and operation phases are analyzed simultaneously, and their carbon reduction potential is quantitatively assessed. The carbon emission calculation for the 81km long new metro line yields a carbon emission of 2.57 million tons of CO2eq in the construction phase, 54,000 tons of CO2eq per year in the operation phase, and a total carbon emission of 5.24 million tons of CO2eq in the 50year operation cycle. The use of renewable materials and prefabricated structures in the construction phase can reduce carbon emissions by 7%. The use of comprehensive carbonreducing measures in the operation phase can reduce carbon emissions by 27%, and the carbon reduction potential of the 50year operation cycle is 17%. The establishment of the model has guiding significance for the quantitative calculation of carbon emissions in the whole life cycle of urban rail transport, and the research results of the carbon reduction measures can provide a reference for urban rail transport to achieve a green and lowcarbon transformation and carbon peak and carbon neutrality in the transport sector.

This paper preliminarily explores the selection range of longitudinal slope for adding stations in existing line renovation project, analyzing the requirements for longitudinal slope from several perspectives, including train stopping smoothness, train starting and braking, station longitudinal drainage, station building and accessibility design, station platform door installation, and station wiring. Some conclusions are presented: (1) Verifying the technical performance of parking braking, starting, and braking of subway trains is the key to determining whether the longitudinal slope of adding stations to existing line sections can be moderately increased; (2) Considering the parking and braking performance of subway trains, as well as the technical performance of train starting and braking, the longitudinal slope of the station should be allowed to be moderately increased. However, considering the design of the station building and the convenience of passenger use, the increase should not be too large; (3) From the perspective of maintenance and repair of switches, it is recommended to ensure that the longitudinal slope of switches does not exceed the existing regulation of 10%.

This study comprehensively summarizes the testing scheme and results of a laddersleeper ballastless track in urban rapid rail transit for safety, stability, and vibration reduction performance compared with an ordinary ballasted track at a maximum speed of 220 km/h on the National Railway Test Center Circular Line in 2023. The test used eight CRH380AJ comprehensive inspection units, including the safety and stability of the wheelset derailment coefficient, wheel load reduction rate, wheelrail lateral force, vertical and lateral dynamic displacement indicators of the rail and sleeper, vertical and lateral vibration characteristics of the rail, and vibration reduction performance of the roadbed surface at a distance of 3.5 m from the centerline of the line. The test results for these indices were lower than the limits of the corresponding standards and close to those for the existing ballasted track. The test results show that the safety, stability, and wheelrail vibration characteristics of the laddersleeper ballastless track in urban rapid rail transit can satisfy the requirements of the line at a speed of 220 km/h. According to different weighting methods, the average vibration reduction of the laddersleeper ballastless track compared with an ordinary ballasted track in urban rapid rail transit can reach 3.35.1 dB and 4.46.8 dB. The test results provide a reference for urban rapid rail transit and intercity railway track vibration reduction technologies.

Quality defects in segment assembly, such as misalignment and ellipse deformation, often occur during shieldtunneling excavation. Construction quality defects threaten tunnel stability and safety. To ensure the safe construction and service of shield tunnels, a quality assessment of the shield segment assembly is necessary during construction. Limited by manual detection methods, traditional sitequality assessment is challenged by low efficiency, limited accuracy, and missing data. Three dimensional laser scanning was introduced to collect pointcloud data during the assembly of the shieldsegment lining. The ellipticity and misalignment values of the shield segments were calculated by the long and shortaxis algorithms and the improved slope segmentation algorithms. Based on the theory of centerpoint extraction of ringseam data, a method for extracting the central axis and center point of a tunnel through ringsegment data fitting was proposed for high precision, efficiency, and automation to detect shieldsegment assembly quality. A shieldtunnel project was conducted to demonstrate and validate the proposed method. The results show that the proposed method can efficiently and automatically assess the assembly quality of shieldconstruction segments.

This study examines shield direct cutting techniques on largediameter piles within the construction project linking Guanzhou Station to University Town North Station on the Guangzhou Metro Line 12. Focusing on piles with diameters of 1,200 mm and reinforcing bars with diameters of 25 mm and 28 mm, the research evaluates the efficacy of critical measures and the resultant quality of pile cutting within shield construction. Findings indicate that a cutter head configuration, incorporating a hob and a tearing knife, successfully penetrates concrete pile foundations containing rebar of the specified diameters. However, a challenge arises when a toothed hob attempts to sever the reinforcing bar directly. It is observed that the tearing knife's secondary action exerts adequate shear force to dissect the reinforcement at the precut location by the hob. Furthermore, employing a boring strategy characterized by a low advancement rate, high rotation speed, and consistent torque has proven to enhance the cutting process for both the pile body and its embedded steel bars. Additionally, the use of split hydraulic rebar shears delivers an improved response to the complications presented by intertwined steel bars within the shield machine's path.