The robustness of transportation networks under emergency events is a key factor in assessing the resilience of urban public transportation systems. To study the emergency response capabilities and resilience performance of complex urban transportation systems during emergency events, this study takes the central urban area of Chongqing as the study region and constructs a bus-metro multilayer transportation network model based on complex network theory to evaluate the robustness and emergency response capabilities of the urban transportation system under different shock modes. Through simulation analysis, the study delves into the catastrophic failure mechanisms and resilience trends of the two-layer network, and investigates the emergency coordination capabilities of metro and bus lines. In response to the vulnerability of single networks in current urban transportation systems during emergencies, an improved load-capacity model is proposed and used to analyze the network resilience under different attack modes. The study results show that: (1) The two-layer network exhibits a slower decline in network efficiency under both shock modes, with its redundancy and multi-path characteristics effectively mitigating the collapse process; (2) In the cascading failure process, the robustness of the two-layer network is consistently superior to that of single bus and subway networks, and the cascading failure caused by the failure of important stations has a more significant impact on network connectivity and efficiency; (3) The two-layer network is more effective in maintaining network connectivity and operational efficiency, especially when facing unexpected events, demonstrating stronger adaptive capacity and robustness. It can effectively share the load, alleviate congestion in single networks, and improve emergency handling efficiency.

To address the problems of unclear functions, unclear positioning, and insufficient integration with rail transit after rail networks are formed in major cities, this study reconstructs an integrated public transportation network system dominated by rail transit from a multi-dimensional perspective of “3-dimensional system, 2-dimensional line network, and 1-dimensional line”. The study analyzes the implementation strategy of rail-bus “dual network” integration in detail, proposes a hierarchical and step-by-step optimization method and implementation path for the “express-trunk-branch” bus network, and applies theoretical methods to the reform of Chengdu's public transportation network system. The research results indicate that the integration and coordination of Chengdu's public transportation networks and the rail-bus “dual network” integration have been significantly improved. This provides valuable reference for the systematic construction of public transportation networks and the optimization of hierarchical bus networks in other large cities.

This study addresses the issues of energy consumption and greenhouse gas emissions caused by the rapid development of urban rail transit and proposes a budget quota-based carbon emission accounting method for rail transit. By integrating carbon emission intensity and economic intensity indicators, a multi-level carbon emission analysis framework—comprising “station-section-line”—is constructed. Using the Fuzhou Metro Line 6 Phase I and its western extension project as a case study, the carbon emission characteristics during the construction phase of rail transit are quantitatively analyzed. The results indicate that the production of construction materials is the primary source of carbon emissions, accounting for 50% to 79% of total emissions, with steel reinforcement, concrete, and cement being the major contributing factors. At the station level, the carbon emission intensity per unit area ranges from 1.67 to 3.40 tCO₂ e/m², influenced by station scale and structural design; the economic intensity ranges from 1.54 to 3.40 tCO₂ e per ten thousand yuan, mainly affected by the low-carbon level of rail transit technologies. At the section level, carbon emission intensity varies significantly with different construction methods. Sections using the cut-and-cover method exhibit higher carbon emissions, with the maximum reaching 36.5 tCO₂ e per double track meter, primarily due to higher demand for steel and concrete. This study provides a scientific basis for low-carbon construction throughout the lifecycle of urban rail transit, and holds significant theoretical and practical value for promoting the green and low-carbon transformation of the rail transit sector.

In response to regulatory requirements for safety evacuation in metro station, based on the location of emergency, this paper summarizes evacuation path and evacuation volume under different conditions. Discussing the method to calculating evacuation time which is in the code for safety evacuation, the view that safety evacuation simulation should be conducted is proposed. And the four key factors affecting the safety evacuation time in design stage are identified in this paper, mainly including evacuation volume, capacity of evacuation facilities, lifting height from the platform to the concourse or other safety zone, and distribution of evacuation facilities on the platform. By comparing the impact of escalator which is in the opposite direction on evacuation capacity, the rationality of using reverse escalator under the emergency evacuation condition are discussed. Considering on practical work experience, it is suggested that the timing of safety evacuation simulation should be advanced to the preliminary design stage.

Transportation infrastructure in urban fringe areas is relatively underdeveloped, and the construction of rail transit will further impact the existing transportation system. It is necessary to optimize the planning and layout of land along the rail transit line around the rail transit station, and create an efficient and dynamic TOD community that integrates rail transit with urban functions and transportation systems, so as to realize rail transit leading urban development. Taking the Pingshan section of Shenzhen Metro Line 16 as an example, based on the TOD planning and design theory, the TOD planning method along the rail transit line is systematically studied from three dimensions: rail station, station area and station group. After the implementation of the plan, a rail development axis of “four complementary areas and two-center linkage” will be formed along Metro Line 16, with differentiated mixed sharing of land use at each rail station, fine ecology of block building, and efficient rail connection and integration, so as to realize the TOD planning and guidance along the subway line and enhance the agglomeration and carrying capacity of the areas along the rail transit.

To address the issues of wasted capacity during off-peak hours in urban rail transit and the increasing urban logistics demand alongside worsening traffic congestion, this paper proposes an online flexible train formation optimization model for mixed passenger and freight transportation in urban rail transit. The research first analyzes the feasibility and necessity of implementing freight services in rail transit systems. Subsequently, a mixed passenger and freight transportation optimization model with online flexible train formation is constructed based on Y-shaped lines, and solved using the GUROBI solver. Results indicate that the flexible train formation scheme for mixed transportation can effectively match capacity with demand, reduce the number of trains required, achieve efficient capacity utilization, and enhance economic benefits through freight revenue, thus providing new perspectives for urban rail transit development.

This study evaluates the coordination efficiency of urban public transportation systems by analyzing bus-subway transfer behavior characteristics, developing a bidirectional “subway-bus” transfer analysis framework based on Beijing's smart card data, which systematically defines subway-to-bus (STB) and bus-to-subway (BTS) transfer modes. An evaluation system encompassing 10 indicators—including transfer bus service area, competition intensity, and spatiotemporal distribution patterns—was constructed, with K-means clustering applied to classify subway stations. Key findings revealed that BTS transfers predominantly occurred during morning peaks while STB transfers concentrated in evening peaks, with both modes exhibiting a consistent 1:2 ratio in travel time and distance between bus and subway segments, alongside an average 6-minute bus waiting time for STB; spatially, high-demand bus transfers clustered around railway stations and sub-centers, with intense competition observed along the Tongzhou-Chaoyang corridor of Subway Line 1; clustering analysis categorized stations into five distinct types for each transfer mode, demonstrating tidal passenger flow-driven differentiation. The research provides theoretical and practical insights for optimizing transfer services and enhancing network coupling efficiency in megacities.

In view of the current problems of insufficient or excessive responses in flood disaster early warning and emergency management, a dynamic classification early warning evaluation for flood disasters has developed. Firstly, the early warning indicator system and quantification method for each warning indicator are developed based on the analysis of the disaster formation-prevention-resistance evolution mechanism of flood disasters in metro stations. The indicator system includes the risk of waterlogging and backflow, vulnerability, and disaster prevention and resistance capacities. Secondly, based on the relationship between hourly rainfall and meteorological warning levels with water accumulation depth, a quantitative method for assessing the risk of waterlogging and backflow in metro stations is proposed. Next, the evaluation methods of vulnerability and disaster prevention-resistance capacities are proposed based on the Analytic Hierarchy Process (AHP) and the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS). Finally, a comprehensive early warning value calculation method and warning level classification criteria for metro station flood disasters are established, and case verification is carried out relying on two actual metro stations. The research results show that this method can effectively achieve dynamic classification early warning on the basis of comprehensively considering the characteristics of subway stations and the flood disasters. The height of entrance and exit steps and the coverage rate of water level monitoring are the key factors affecting the early warning level. In practical applications, further attention should be paid to the real-time monitoring of data such as water accumulation depth and rainfall. The research outcomes can provide a decision-making support for advanced forecasting, early warning, and precise hierarchical response to flood disasters in metro stations.

The facade of the building is an important part of the image and urban style of the elevated station, and it plays a crucial role in the design of the station form. This research firstly analyzes the existing situation and problems of the facade of the elevated station through on-site investigation. Subsequently, the prefabricated construction technology is applied to the construction of elevated stations. The plasticity of concrete provides a new possibility for the innovation of the form design of elevated stations. On this basis, the design strategy of the station facade is put forward from the perspectives of design and construction respectively. In order to demonstrate the pertinence and effectiveness of the design strategy of the facade of the elevated station, the design practice is carried out in combination with the engineering projects of Dayanhe Street Station and Xiuhu Station of Zhejiang Jinyi East Urban Rail Transit. Finally, the organic balance between the diversity of station facade design and the standardization of assembled components is realized. The research results can provide important reference value and guiding significance for the design and construction of the facade of urban rail transit elevated stations.

To address the insufficient interdisciplinary collaboration and low efficiency in generating digital design outputs during the design process of subway station entrances and exits, and based on this, establishes a collaborative way of professional data of entrances and exits architecture and structure, and then develops a digital collaborative intelligent design tool for subway station entrances and exits based on general BIM design software. Finally, it takes the entrance and exit of a new subway station in Qingdao as an example for engineering application. The research results show that the collaborative intelligent design tool for entrances and exits has realized the functions of BIM model establishment and modification, 2D drawing generation and so on, which are needed by architectural and structural designers for 3D forward design of entrances and exits. Intelligent design tools digitally encapsulate the design experience of entrances and exits. After practical engineering application and statistical analysis, the design efficiency is improved by 2.7 times.

This study addresses public complaints regarding vibration and noise disturbances along an operational metro line with short-sleeper monolithic trackbed. Field investigations and measurements were conducted at both the metro track and sensitive receptor locations to analyze the root causes of these disturbances. Multiple mitigation measures were implemented, including the replacement of vibration-damping fasteners, rail profile adjustment, and rail grinding. The performance of floating rail fasteners was evaluated through vehicle-track coupling analysis and finite element modeling of the tunnel-soil-building system. Post-modification measurements and resident surveys were performed to assess the effectiveness of the implemented solutions. Results showed reductions in indoor vibration levels (VL_Zmax) of 6.4 dB during daytime and 8.3 dB during nighttime operations, while the equivalent sound pressure levels of structure-borne noise decreased by 1.36 dB (A) and 1.88 dB (A) for daytime and nighttime periods, respectively. Resident feedback confirmed significant improvements in the vibration and noise environment. This case study provides valuable insights for addressing similar vibration and noise issues in Chinese metro systems.

To investigate the feasibility of installing embedded rail tracks for trams on continuous beam bridges, an embedded rail track-bridge element model is proposed, and a static model of continuous welded rail (CWR) system is established for the bridge structure. The longitudinal forces and deformations of the CWR system under bridge temperature loads are analyzed. Using beam-rail relative displacement as the evaluation criterion, this study assesses the feasibility of CWR installation schemes and examines the effects of annual bridge temperature variation, longitudinal resistance of polymer materials, and rail expansion joint configurations on the mechanical behavior of the CWR system. Results indicate that the annual bridge temperature difference significantly affects both the beam-rail relative displacement and rail additional expansion force, exhibiting an approximately linear increase with temperature variation. Maximum values of both parameters occur at the right beam joint of the second continuous beam bridge. With an annual temperature difference of 30℃, the beam-rail relative displacement reaches 12.79 mm, exceeding the allowable limit of 6.20 mm. Since adjusting the longitudinal resistance of polymer materials proves insufficient to maintain displacement within limits, rail expansion joints are required. The installation of grooved rail expansion joints at the right beam ends of both the 11th and 19th spans is recommended to ensure acceptable beam-rail relative displacement.

To address the challenges of predicting the interaction effects of ground displacement and mitigating surface subsidence risks in double-line parallel shield tunneling, this study proposes a three-dimensional analytical method for displacement in unsaturated soil. Based on the initial solution for unsaturated soil under buried-depth loading, a three-dimensional analytical solution for ground displacement induced by double-line parallel shield tunneling is derived using the superposition principle, while comprehensively accounting for multiple influencing factors such as construction loads and soil loss. The validity and reliability of the proposed solution are verified through comparisons with real-world engineering cases. The results indicate that the longitudinal distance between tunnels and the transverse spacing of their axes significantly influence soil displacement: reducing the longitudinal spacing from 120 m to 0 m increases the peak total surface subsidence from 6.08 mm to 9.10 mm (a 50.0% increase); decreasing the transverse axis spacing from 1D to 9D reduces horizontal ground displacement by 49.2%; and lowering the depth-to-diameter ratio Z/D from 3 to 1 causes the peak subsidence to surge from 15.9 mm to 49.4 mm (a 210.7% increase), resulting in a deeper and narrower settlement trough. The study highlights that rational control of the longitudinal spacing of excavation faces, transverse axis spacing, and depth-to-diameter ratio is key to reducing surface subsidence risks during double-line parallel shield tunneling. The proposed analytical method offers a theoretical basis for optimizing construction parameters and mitigating subsidence risks.

To solve the joints at the interface between the main body and the ancillary structure of the subway station cannot be pre embedded with embedded waterproof components, the author and their team have developed a slot type polymer coated waterstop and its supporting products and construction technology. The internal core material of the waterstop is made of 1 mm thick steel plate pre processed into a “T” structure, surrounded by 1.2 mm thick polymer waterproof and anti-corrosion coating. Using matching fixing glue to fix the cold joint section, using matching “L”-shaped connecting plates and matching connecting glue to connect the waterstop into a ring, achieving the middle buried waterstop of the cold joint. This new waterproofing solution has been tested in the laboratory and proven to effectively solve the problem of interface cold joint leakage in underground projects such as subways and civil air defense in Beijing, Xuzhou, Zhoukou, and other areas. It has good promotion and application significance and can be used as a reference for similar projects.

Under inclement weather conditions such as rain and snow, the wheel-rail adhesion characteristics of urban rail transit systems significantly deteriorate, posing failure risks to the overspeed protection function of Automatic Train Control (ATC) systems. To enhance the global robustness of ATC systems, this study investigates optimization strategies for ATC overspeed protection control under low-adhesion conditions. First, the operational mechanism of ATC overspeed protection is systematically analyzed through the Safety Braking Model, Guaranteed Emergency Braking Rate (GEBR), and adhesion braking principles. Second, by examining the mismatch between the rigid GEBR setting in engineering practice and the stochastic fluctuation of adhesion coefficients in actual operations, this research reveals a chain failure mechanism: “adhesion degradation→braking performance reduction→GEBR dynamic mismatch→safety threshold breach in braking distance”. Finally, a MATLAB-based simulation model integrating dynamic wheel-rail adhesion characteristics is developed for ATC overspeed protection, with validation through specific accident cases. Results demonstrate that compared with existing rain-snow mode protection strategies, the proposed multi-objective collaborative optimization dynamic control strategy achieves refined coordination of GEBR values and system ceiling speed, effectively balancing train braking safety and system operational efficiency in low-adhesion environments.

To meet the demand for efficient, low-power, and secure authentication mechanisms in the safety monitoring and maintenance of rail transit equipment, this study systematically investigates the implementation of cross-domain identity authentication. First, a system architecture is designed using a super SIM card as the identity carrier, combined with Bluetooth Low Energy (BLE) technology for rapid data exchange between devices. Second, a high-efficiency anonymous identity authentication scheme integrating a blinded ECDSA algorithm is proposed. Finally, the proposed scheme is compared with supervised anonymous authentication schemes and other traditional authentication algorithms regarding computation and communication overheads. The results indicate that, compared to NIST-standard-based ECDSA and traditional ECC algorithms, the proposed scheme demonstrates superior performance in signature generation with the shortest overall runtime. Additionally, authentication efficiency is improved by 43.8% compared to supervised anonymous authentication schemes, verifying the effectiveness and feasibility of the proposed approach. These findings provide a valuable reference for intelligent security monitoring and maintenance of equipment in low-altitude economic sectors and the rail transit field.

In major metropolitan areas, the severe congestion during peak hours at urban rail transit stations necessitates comprehensive research on train timetable, particularly focusing on the implementation of short-turn and full-length routing strategies coupled with passenger flow control measures. This study takes the morning peak period of urban rail transit lines as its research subject, establishing an optimization model for train timetables by considering passenger travel costs and enterprise operational expenses as the objective functions, while incorporating constraints such as train departure intervals, vehicle capacity, passenger flow control, and routing strategies. Utilizing a linear weighting method to balance both passenger and operational costs, the research develops a genetic algorithm for model solution, with Hangzhou Metro Line 4 serving as a case study. The findings demonstrate that optimized train schedules effectively reduce passenger travel costs, while the implementation of short-turn and full-length routing strategies contributes to lowering operational expenses for enterprises. Furthermore, the integration of passenger flow control measures significantly alleviates station congestion levels. This research on timetable optimization, based on routing strategies and passenger flow control, provides valuable insights for rail transit enterprises in formulating effective peak-hour dispatching strategies.

Aiming at the problems existing in the practice, location and operation of Metro-based Underground Logistics System (M-ULS), the research ideas and improvement measures for the existing problems of M-ULS are proposed. Firstly, it summarises the shortcomings of domestic and foreign construction feasibility and practice research, and puts forward the medium- and long-term feasibility planning for the development of M-ULS; secondly, it analyses the differences between the siting of key nodes of M-ULS and the reality, and points out the ideas for subsequent research; finally, it summarises the factors affecting the overall operation of M-ULS and the influencing factors that have not yet been studied in depth, and points out several key technologies for realising the informatisation of the operation of M-ULS. and points out several key technologies to realise the informatisation of M-ULS operation. The results of the study show that China has a realistic foundation for the construction of M-ULS, but it needs to formulate appropriate cargo transport standards, establish a perfect evaluation system and improve the technologies required for information-based operation.

To alleviate platform congestion caused by a large number of passengers exiting metro stations near event venues before the start of large-scale events, this study proposes a method that staggers the arrival times of trains in both directions and incorporates a skip-stop strategy. A mathematical optimization model is developed to minimize the platform dwell time of outbound passengers, the risk of crowding on the platform, and the number of skip-stop operations. Furthermore, an iterated local search algorithm is designed, taking into account the characteristics of passenger flow and the metro timetable during large-scale events. The algorithm explores feasible neighboring solutions in two ways: by adjusting train running and stopping times, and by modifying stop plans. Using data from a major event in Nanchang as a case study, the effectiveness of the model and algorithm is validated. The results show that the proposed iterated local search algorithm can quickly obtain high-quality solutions. After optimization, the maximum number of passengers on the platform decreased from 2,951 to 1,006, the average platform exit time for passengers was reduced by 94.7 seconds, and the platform crowding risk was reduced by 94%. The strategies of staggering train arrivals and implementing skip-stops can effectively reduce passenger exit times and alleviate congestion at stations near event venues before large-scale events begin.

To address the challenge of certain rail transit lines facing closure due to continuously declining ridership, this study takes the evolutionary trajectory of Japan's rail transit development as a starting point and employs a multi-case comparative analysis. The research thoroughly investigates the triggering factors, policy frameworks, and supporting measures for the closure of low-ridership lines. The results show that changes in population and industrial structure, as well as shifts in travel modes, are the core factors leading to the sustained decline in rail transit ridership. At the same time, increased maintenance costs caused by aging infrastructure and severe revenue-expenditure imbalances have further worsened line operations. In response, Japan has established evaluation systems centered on transport density to classify and assess low-ridership lines, and has implemented systematic governance schemes covering ridership cultivation and cost control. For lines where closure is unavoidable, innovative alternatives such as Bus Rapid Transit (BRT) dedicated lanes and demand-responsive transit have been adopted, effectively addressing operational challenges and ensuring residents’ basic mobility needs. By comprehensively analyzing the problem of low-ridership rail transit closures and the corresponding measures taken in Japan, this study summarizes relevant experiences and lessons, aiming to provide references for the future operation and transformation of rail transit in China.