Metro systems are important transport infrastructures in megacities,and their long-term operational safety is challenged by frequent external disturbances,such as environmental extremes and human construction activ-it...Metro systems are important transport infrastructures in megacities,and their long-term operational safety is challenged by frequent external disturbances,such as environmental extremes and human construction activ-ities.A metro system must be resilient to resist,adapt to,and recover its performance when such disruptions occur.Current studies on metro system resilience often lack a comprehensive view from a complex system perspective,leading to a plethora of choices for methods of analysis and indicators applied to different metro systems and external disturbances.Therefore,the present paper aims to provide a comprehensive review of the topics and works revolving around the resilience of metro systems.It first clarifies the concept of metro system resilience based on classical definitions from a technical perspective.Metro resilience encompasses both the structural and operational aspects of metro systems,including their damage mechanisms,analysis methods and indicators of resilience.Methods for enhancing metro system resilience across structural,operational and monitoring dimensions are explored.Finally,future research directions are discussed,emphasizing the impor-tance of considering the"system of systems"formed by interdependent infrastructure,refining uncertainty analysis,and investigating the opportunities arising from the application of artificial intelligence for improving metro system resilience against external disturbances.展开更多
Purpose–To address the problem that the current train operation mode that train selects one of several offline pre-generated control schemes before the departure and operates following the scheme after the departure,...Purpose–To address the problem that the current train operation mode that train selects one of several offline pre-generated control schemes before the departure and operates following the scheme after the departure,energy-saving performance of the whole metro system cannot be guaranteed.Design/methodology/approach–A cooperative train control framework is formulated to regulate a novel train operation mode.The classic train four-phase control strategy is improved for generating specific energy-efficient control schemes for each train.An improved brute force(BF)algorithm with a two-layer searching idea is designed to solve the optimisation model of energy-efficient train control schemes.Findings–Case studies on the actual metro line in Guangzhou,China verify the effectiveness of the proposed train control methods compared with four-phase control strategy under different kinds of train operation scenarios and calculation parameters.The verification on the computation efficiency as well as accuracy of the proposed algorithm indicates that it meets the requirement of online optimisation.Originality/value–Most existing studies optimised energy-efficient train timetable or train control strategies through an offline process,which has a defect in coping with the disturbance or delays effectively and promptly during real-time train operation.This paper studies an online optimisation of cooperative train control based on the rolling optimisation idea,where energy-efficient train operation can be realised once train running time is determined,thus mitigating the impact of unpredictable operation situations on the energy-saving performance of trains.展开更多
Metro system has experienced the global rapid rise over the past decades. However,few studies have paid attention to the evolution in system usage with the network expanding. The paper's main objectives are to ana...Metro system has experienced the global rapid rise over the past decades. However,few studies have paid attention to the evolution in system usage with the network expanding. The paper's main objectives are to analyze passenger flow characteristics and evaluate travel time reliability for the Nanjing Metro network by visualizing the smart card data of April 2014,April 2015 and April 2016. We performed visualization techniques and comparative analyses to examine the changes in system usage between before and after the system expansion. Specifically,workdays,holidays and weekends were specially segmented for analysis.Results showed that workdays had obvious morning and evening peak hours due to daily commuting,while no obvious peak hours existed in weekends and holidays and the daily traffic was evenly distributed. Besides,some metro stations had a serious directional imbalance,especially during the morning and evening peak hours of workdays. Serious unreliability occurred in morning peaks on workdays and the reliability of new lines was relatively low,meanwhile,new stations had negative effects on exiting stations in terms of reliability. Monitoring the evolution of system usage over years enables the identification of system performance and can serve as an input for improving the metro system quality.展开更多
Floods have become increasingly destructive with climate change,resulting in the inundation of urban metro systems.This study complied with global data on flooded metro lines in recent decades.Based on these data,a fr...Floods have become increasingly destructive with climate change,resulting in the inundation of urban metro systems.This study complied with global data on flooded metro lines in recent decades.Based on these data,a framework incorporating machine learning(ML)with geographic information system(GIS)was developed to predict flood susceptibility in urban metro systems.To address the scarcity of subway flooding data,this study proposed a novel approach to generate a database for training and testing using ML and GIS.The 7.20 flood event in Zhengzhou,China,was analyzed as a case study.The optimal ML model was selected by comparing predicted flood states with recorded flooded metro stations.Flood susceptibility for the Zhengzhou metro system under future extreme rainfall scenarios was then predicted.Results demonstrated that the number of flooded stations and their flood susceptibility increased with rainfall intensity.These findings highlight the scale and vulnerability of metro systems,providing critical insights for developing resilient underground infrastructure.展开更多
Stray currents from DC metro systems intrude into the grounded neutrals of large power transformers,posing a major threat to the differential relay protection of transformer.In this paper,the performance of harmonic b...Stray currents from DC metro systems intrude into the grounded neutrals of large power transformers,posing a major threat to the differential relay protection of transformer.In this paper,the performance of harmonic blocking based differential relay protection considering neutral stray currents(NSCs)from DC metro systems is thoroughly investigated.The findings reveal that relays may fail to clear internal faults in some scenarios because they are blocked due to NSC-induced harmonic currents.To improve the reliability of differential relay protection,a method for preventing incorrect operation is proposed using a skewness-based criterion to detect the presence of NSCs.Then,the relay is unblocked when an internal fault is simultaneously detected by the novel internal fault detection block.The proposed method is resistant to current transformer saturation and accounts for NSC fluctuations.Various time-domain simulations conducted in PSCAD/EMTDC verify the effectiveness of the proposed method.展开更多
As an integral component of modern urban transportation,metro systems have significantly contributed to alleviating urban traffic congestion and reducing carbon emissions.However,concerns about air quality in its conf...As an integral component of modern urban transportation,metro systems have significantly contributed to alleviating urban traffic congestion and reducing carbon emissions.However,concerns about air quality in its confined environment,particularly the pollution by BTEX(benzene,toluene,ethylbenzene,and xylene),are growing.This study takes the Chengdu metro system as a case to evaluate the concentrations of BTEX and their potential health impacts on the public.Sampling was conducted in metro stations,carriages,and tunnels.The study found that the BTEX pollution levels in the metro system were 7.85±3.03µg/m^(3) in summer and 8.44±3.38µg/m^(3) in autumn,with toluene and xylene being the highest concentrations.No significant differences were observed between the halls and platforms,interchanges and non-interchanges,off peak and evening peaks in carriages,or in-service and off-service in tunnels.However,seasonal variations were pronounced.Health risk assessments indicated that while non-cancer risks were negligible,cancer risks in both summer and autumn(excluding passengers)exceeded the acceptable threshold of 1×10^(-6),potentially posing health threats to long-term exposed populations,particularly metro workers.This study provides a scientific basis for air quality management within metro systems and highlights the need for regulatory bodies to pay further attention to air quality issues,promoting the formulation and implementation of relevant control measures to protect the health and safety of passengers and metro workers.展开更多
This paper explores the challenges of controlling complex metro systems,which are influenced by uncertain and uncontrollable large passenger flow impacts.Traditionally,flow-limiting measures during peak periods have b...This paper explores the challenges of controlling complex metro systems,which are influenced by uncertain and uncontrollable large passenger flow impacts.Traditionally,flow-limiting measures during peak periods have been based on experience rather than scientific theory.To bridge this gap,we introduce a novel network analysis method inspired by control centrality theory.This approach assesses the impact of traffic loads from single or multiple sources on any node within the metro network.Our method provides a scientific basis for operators to develop policies for managing overloaded traffic,enhancing both safety and efficiency in metro system operations.展开更多
Metro systems play a crucial role in enhancing the urban economy,but the serious dust pollution during its construction poses a significant threat to the health of workers.Widely used for dust control in metro systems...Metro systems play a crucial role in enhancing the urban economy,but the serious dust pollution during its construction poses a significant threat to the health of workers.Widely used for dust control in metro systems,the current forced ventilation technology is characterized by low dust control efficiency.In this study,an innovative arc device with efficient dust control and convenient application was proposed based on the forced ventilation.Subsequently,the orthogonal experimental method was adopted to explore the effects of air supply outlet position(L),air supply volume(Q),and air supply mode(M)on the airflow-dust distribution characteristics.The results indicated that compared with the traditional forced ventilation,the application of arc device can shorten the safe entry time after blasting operations by 9.9%–32.1%within the air supply volume of 804–1876 m3/min,effectively improving the construction efficiency and reducing the construction costs.In other words,the arc device can achieve the same dust control requirements with a smaller air supply volume,which improves the engineering applicability of forced ventilation in long-distance tunnel excavation while reducing ventilation energy consumption.Furthermore,the theoretical optimal combination scheme(L=35 m,Q=1876 m3/min,M=arc device)composed of the optimal levels of three factors achieved a 13%improvement in dust control compared to the experimental optimal combination scheme determined by the minimum safe entry time.This study can provide new strategies for improving the dust control performance of forced ventilation used in metro system construction.展开更多
During special events,some metro lines and stations may alter their first train schedules to an earlier time,while others remain unchanged.These adjustments can result in longer transfer waiting times for passengers,n...During special events,some metro lines and stations may alter their first train schedules to an earlier time,while others remain unchanged.These adjustments can result in longer transfer waiting times for passengers,negatively impacting the overall quality of metro services.Thus,optimizing first train schedules is essential,as it directly influences morning service quality and passengers’ability to complete their journeys.However,this task is complicated by the elastic nature of passenger flow and inflexibility of published sched-ules.To tackle this issue,this paper presents a mathematical model that captures the elas-tic demand for early-morning travel.It also proposes an optimization approach for reducing both the adjustment costs of first-train schedule changes and transfer redun-dancy time throughout the network.By applying linearization techniques,the problem is reformulated into a linear programming model.The effectiveness of this method is demon-strated through a case study of the Shenzhen metro,which showed a 9.1%reduction in average transfer redundancy time by adjusting the departure times of first trains on two lines and at ten stations during a special event.These results indicate that for metro sys-tems with fixed first train schedules,carefully adjusting departure times at specific stations can effectively accommodate early-morning passenger needs and improve the overall quality of morning services.展开更多
Metro systems in megacities such as Beijing,Shenzhen,and Guangzhou are under great passenger demand pressure.During peak hours,it is common to see oversaturated conditions(i.e.,passenger demand exceeds network capacit...Metro systems in megacities such as Beijing,Shenzhen,and Guangzhou are under great passenger demand pressure.During peak hours,it is common to see oversaturated conditions(i.e.,passenger demand exceeds network capacity)and a popular control intervention is to restrict the entering rate by setting up out-of-station queueing with crowd control barriers.The out-of-station waiting can make up a substantial proportion of total travel time but is often ignored in the literature.Quantifying out-of-station waiting is important to evaluating the social benefit and cost of metro services;however,out-of-station waiting is difficult to estimate because it leaves no trace in smart card transactions of metros.In this study,we estimate the out-of-station waiting time by leveraging the information from a small group of transfer passengers—those who transfer from nearby bus routes to the metro station.Based on the transfer interval of this small group,we infer the out-of-station waiting time for all passengers by a Gaussian Process regression and then use the estimated out-of-station waiting time to build queueing diagrams.We apply our method to the Tiantongyuan North station of Beijing metro;results show that the maximum out-of-station waiting time can reach 15 min,and the maximum queue length can be over 3000 passengers.We find out-of-station waiting can cause significant travel costs and thus should be considered in analyzing transit performance,mode choice,and social benefits.To the best of our knowledge,this paper is the first quantitative study for out-of-station waiting time.展开更多
Several studies,from both the private sector(McKinsey,Engie,and EY)and international organizations(OECD,World Bank,and IMF),have shown that urban population in cities will grow in the coming decades.This growth implie...Several studies,from both the private sector(McKinsey,Engie,and EY)and international organizations(OECD,World Bank,and IMF),have shown that urban population in cities will grow in the coming decades.This growth implies an increased pressure on all urban networks-transporting people,goods,water,waste,electricity,information,heat,and so on.These functions are executed by urban infrastructures entailing huge investments.We have dedicated our research to the optimization of infrastructures and more precisely of metro systems to offer global solutions to fulfill city needs-the multifunctional metro.The innovative multifunctional metro system incorporates several other urban networks—optical fiber,high-voltage electric cables,water and sewage pipes,geothermal piles,pneumatic systems,merchandise shuttles,and many others depending on the context of each project.The aim of the multifunctional metro is to meet several needs of cities with one common infrastructure.Adding a function to a system increases its complexity.For this reason,we focus our research on the application of methods that allow better management of the complexity:systems engineering applied to infrastructures.In the first part of the paper,we will present a benchmark of multipurpose infrastructures across the world and the benefits of such a system for cities.In the second part,we will present and illustrate the concept of the multifunctional metro.Next,we will present the method based on systems engineering to analyse multifunctional systems.Finally,the concept of a multifunctional metro is illustrated with a case study on the future fifth metro line of Lyon,France.In conclusion,we will discuss the current barriers for the development of multifunctional infrastructures.展开更多
In order to fully utilize the regenerative braking energy of metro trains and stabilize the metro DC traction busbar voltage,a hybrid regenerative braking energy recovery system with a dual-mode power management strat...In order to fully utilize the regenerative braking energy of metro trains and stabilize the metro DC traction busbar voltage,a hybrid regenerative braking energy recovery system with a dual-mode power management strategy is proposed.Firstly,the construction of the hybrid regenerative braking energy recovery system is explained.Then,based on the power demand of low-voltage load in metro stations,a dual-mode power management strategy is proposed to allocate the reference power of each system according to the different working conditions,and the control methods of each system are set.Finally,the correctness and effectiveness of the dual-mode strategy are verified through simulation,and the proposed braking energy utilization scheme is compared with other singleform utilization schemes.The results illustrate that the hybrid system with the dual-mode strategy can effectively recycle the regenerative braking energy of metro train and inhibit the busbar voltage fluctuation;the proposed braking energy utilization scheme has certain advantages on energy recovery and DC bus voltage stabilization compared with other single-form schemes;the proposed power management strategy can correctly allocate the reference power of each system with a lower construction cost.展开更多
Construction management innovation system of metro in China is put forward in this paper. Guidelines,objective system,new management ideas and contents of this construction management innovation system are set forth p...Construction management innovation system of metro in China is put forward in this paper. Guidelines,objective system,new management ideas and contents of this construction management innovation system are set forth particularly. The construction management innovation system of metro can meet needs of building harmonious and economized society and realizing sustainable development in China,it is also an important part of science & technology innovation system.展开更多
On the basis of analyzing the influencing factors and harmfulness of stray current, and discussing the existing problems of monitoring and prevention system for stray current, the integrated monitoring and prevention ...On the basis of analyzing the influencing factors and harmfulness of stray current, and discussing the existing problems of monitoring and prevention system for stray current, the integrated monitoring and prevention system for stray current in metro was developed. A net system of distributed computers for monitoring was set up. It can monitor the distribution of stray current in metro and the corrosion of the metal structure in the whole line. According to the situation of monitoring it can also control the drainage of its tank to reach the best effect and eliminate the negative effect of polarity drainage. By using the new type unilateral electric device, the problem of burning the rail by electric arc can be avoided. The unilateral electric device can be connected with the monitoring net system directly to realize the monitor in line and improve the reliability of the device.展开更多
The mechanism of rail corrugation remains unclear,and the research methods require improvement.The vibration characteristics represent the system's external manifestations,but a comprehensive analysis is still lac...The mechanism of rail corrugation remains unclear,and the research methods require improvement.The vibration characteristics represent the system's external manifestations,but a comprehensive analysis is still lacking.Taking the vibration characteristics of the wheel-rail system as a starting point,this study investigates the formation mechanisms of rail corrugation on measured metro lines.The line sections included both steel spring floating slab tracks and long sleeper embedded tracks.First,the wavelength and frequency attributes of rail corrugation were obtained through field measurements.Then,referencing line conditions,three-dimensional finite element numerical models were established,frequency response calculations were performed,and the relationship between the vibration responses of the wheel-rail system and rail corrugation was analyzed.Finally,a parameter sensitivity analysis of the wheel-rail system was conducted to control the further development of rail corrugation.The results show distinct corrugation phenomena on both inner and outer rails in the measured sections.The characteristic wavelengths of inner and outer rail corrugation on the steel spring floating slab track are 34 mm and 59 mm,respectively,and the characteristic wavelengths of inner and outer rail corrugation on the long sleeper embedded track are 46 mm and 47 mm,respectively.The frequency response analysis indicates that the numerical results exhibit eigenfrequencies close to the passing frequencies of the measured corrugations.The formation mechanism of inner rail corrugation on the steel spring floating slab track is attributed to the third-order bending vibration of the wheelset,which leads to the generation of inner rail corrugation.In contrast,the formation mechanism of outer rail corrugation is attributed to the lateral bending vibration of the outer rail.For the long sleeper embedded track,inner rail corrugation is generated by the lateral bending vibration of the inner rail,while outer rail corrugation results from the lateral bending vibration of the outer rail.Appropriate adjustments to the fastener's vertical and lateral stiffness,as well as the steel spring's vertical and lateral stiffness,can shift the rail corrugation eigenfrequencies,thereby inhibiting the development of corrugation with the original wavelength.Changes in other parameters have no effect on the rail corrugation eigenfrequencies and only influence the development speed of corrugation with the original wavelength.This research effectively elucidates the cause of rail corrugation from the system vibration perspective and provides a valuable complement to the corrugation analysis method.展开更多
Investigations into rail corrugation within metro systems have traditionally focused on specific mechanisms,thereby limiting the generalizability of proposed theories.Understanding the commonalities in rail corrugatio...Investigations into rail corrugation within metro systems have traditionally focused on specific mechanisms,thereby limiting the generalizability of proposed theories.Understanding the commonalities in rail corrugation across diverse metro lines remains pivotal for elucidating its underlying mechanisms.The present study conducted extensive field surveys and tracking tests across 14 Chinese metro lines.By employing t-distributed stochastic neighbor embedding(t-SNE)for dimensional reduction and employing the unsupervised clustering algorithm DBSCAN,the research redefines the classification of metro rail corrugation based on characteristic information.The analysis encompassed spatial distribution and temporal evolution of this phenomenon.Findings revealed that floating slab tracks exhibited the highest proportion of rail corrugation at 47%.Notably,ordinary monolithic bed tracks employing damping fasteners were more prone to inducing rail corrugation.Corrugation primarily manifested in curve sections with radii between 300 and 500 m,featuring ordinary monolithic bed track and steel-spring floating slab track structures,with wavelengths typically between 30 and 120 mm.Stick–slip vibrations of the wheel–rail system maybe led to short-wavelength corrugations(40–60 mm),while longer wavelengths(200–300 mm)exhibited distinct fatigue damage characteristics,mainly observed in steel-spring floating slab tracks and small-radius curve sections of ordinary monolithic bed tracks and ladder sleeper tracks.A classification system comprising 57 correlated features categorized metro rail corrugation into four distinct types.These research outcomes serve as critical benchmarks for validating various theories pertaining to rail corrugation formation.展开更多
Power supply is one of the key components to support subway operation, and subway projects usually have the characteristics of low pollution and high efficiency. The number of vehicles in our country is increasing, an...Power supply is one of the key components to support subway operation, and subway projects usually have the characteristics of low pollution and high efficiency. The number of vehicles in our country is increasing, and the traffic pressure is increasing. Under such a condition, the construction of subway has effectively shared some of the traffic pressure, meeting the needs of urban traffic development as much as possible. If you want to make the subway run normally, then the power supply should be continuously reliable and stable. There are three power supply methods for subway, namely centralized power supply, decentralized power supply and hybrid power supply. In the process of implementation in reality, scientific selection and application must be carried out according to the technical requirements.展开更多
At this stage, the rapid social progress, the development of China's subway engineering construction has also been improved. Relevant research points out that the future metro power dispatching information managem...At this stage, the rapid social progress, the development of China's subway engineering construction has also been improved. Relevant research points out that the future metro power dispatching information management system should have high precision and powerful real-time monitoring function, which can accurately locate the fault location while carrying out early warning. In addition, through the above process, the related failure events can be specially handled to form the whole process monitoring of the whole system. In the process of establishing the knowledge base, it belongs to the reference process of historical experience information, so as to improve the efficiency of solving power failure and meet the development needs of the whole system.展开更多
This study offers valuable insights into the relationship between metro ridership patterns and the spatial transformations around Delhi Metro stations,underscoring the role of mass transit infrastructure in shaping ur...This study offers valuable insights into the relationship between metro ridership patterns and the spatial transformations around Delhi Metro stations,underscoring the role of mass transit infrastructure in shaping urban land use and ecosystem landscapes.The primary objective is to assess how high-ridership metro stations can positively influence urban development,particularly regarding socio-economic and ecological dimensions.Integrating primary survey data with ridership statistics from the Delhi Metro Rail Corporation(DMRC),the research identifies key interchange stations,such as Kashmere Gate and Rajiv Chowk,which exhibit substantial passenger volumes.Utilising GIS-based spatial analysis and remote sensing techniques,land use changes within a 500-meter buffer zone around these stations are considered,focusing on built-up areas,green cover,and open space availability.Time-series satellite imagery generates comparative maps illustrating land use changes pre-and post-introduction of metro services.The analysis reveals that high-ridership stations are linked to significant commercial densification,particularly near Rajiv Chowk,with a p-value of 0.172.Conversely,peripheral stations like Dwarka Sector 21 indicate residential growth trends,with a p-value of 0.087 for residential areas.Importantly,two land use categories—Green Space(t=-2.33,p=0.045)and Open Space(t=3.57,p=0.006)—show statistically significant reductions,highlighting the ecological impacts of metro infrastructure.The findings suggest that metro systems can promote commercial clustering in urban centres while fostering residential growth in surrounding areas.Overall,the study highlights the potential of metro systems to enhance accessibility,reshape urban ecosystems,and encourage the development of compact urban forms.The implications for urban planning advocate for transit-oriented development(TOD)as a strategic approach to manage growth,minimise sprawl,and ensure sustainable and inclusive development.展开更多
Background:Shift-based occupations have been consistently linked to adverse psychological outcomes;however,limited research has examined how work schedule type and physical activity are jointly associated with mental ...Background:Shift-based occupations have been consistently linked to adverse psychological outcomes;however,limited research has examined how work schedule type and physical activity are jointly associated with mental health and job stress in public transportation employees,a population frequently exposed to irregular hours and safety-critical responsibilities.This study investigated the associations between work schedule type and physical activity with mental health indicators and job stress among Seoul Metro employees.Methods:A cross-sectional survey was administered to 298 full-time male employees of Seoul Metro.Participants were categorized by work schedule(shift vs.regular)and physical activity level(regular,irregular,none)following American College of Sports Medicine(ACSM)guidelines.Mental health(sleep disturbance,depression,anxiety,loneliness)was assessed using validated binary indicators,and job stress was measured with the Korean Occupational Stress Scale–Short Form(KOSS-SF).Group differences were analyzed using chi-square tests,t-tests,and one-way ANOVA with effect sizes,and binary logistic and multiple regression analyses were conducted to identify predictors.Results:Shift workers reported significantly higher sleep disturbance and anxiety compared to regular daytime workers(p<0.05).Employees who participated in regular physical activity had lower odds of sleep disturbance and depression(p<0.05)and showed lower job stress scores compared with inactive workers.Work schedule type and physical activity were independently associated with mental health and job stress among transit employees.Conclusion:These findings underscore the dual influence of work schedule and physical activity on the psychological and occupational well-being of public transit employees.Promoting regular physical activity may buffer occupational stress among employees engaged in shift-based work.Workplace interventions that support physical activity participation and improve shift planning may enhance employee well-being.展开更多
基金supported by National Key R&D Program of China 2024YFC3808804National Natural Science Foundation of China NO.52478411+1 种基金China Scholarship Council No.202506260003Jinan Rail Transit Group Co.,Ltd(ggjn-sd-gd2022008fw).
文摘Metro systems are important transport infrastructures in megacities,and their long-term operational safety is challenged by frequent external disturbances,such as environmental extremes and human construction activ-ities.A metro system must be resilient to resist,adapt to,and recover its performance when such disruptions occur.Current studies on metro system resilience often lack a comprehensive view from a complex system perspective,leading to a plethora of choices for methods of analysis and indicators applied to different metro systems and external disturbances.Therefore,the present paper aims to provide a comprehensive review of the topics and works revolving around the resilience of metro systems.It first clarifies the concept of metro system resilience based on classical definitions from a technical perspective.Metro resilience encompasses both the structural and operational aspects of metro systems,including their damage mechanisms,analysis methods and indicators of resilience.Methods for enhancing metro system resilience across structural,operational and monitoring dimensions are explored.Finally,future research directions are discussed,emphasizing the impor-tance of considering the"system of systems"formed by interdependent infrastructure,refining uncertainty analysis,and investigating the opportunities arising from the application of artificial intelligence for improving metro system resilience against external disturbances.
基金This research was supported by the National Natural Science Foundation of China(Grant No.71971016).On behalf of all co-authors,the corresponding author states that there is no conflict of interest.
文摘Purpose–To address the problem that the current train operation mode that train selects one of several offline pre-generated control schemes before the departure and operates following the scheme after the departure,energy-saving performance of the whole metro system cannot be guaranteed.Design/methodology/approach–A cooperative train control framework is formulated to regulate a novel train operation mode.The classic train four-phase control strategy is improved for generating specific energy-efficient control schemes for each train.An improved brute force(BF)algorithm with a two-layer searching idea is designed to solve the optimisation model of energy-efficient train control schemes.Findings–Case studies on the actual metro line in Guangzhou,China verify the effectiveness of the proposed train control methods compared with four-phase control strategy under different kinds of train operation scenarios and calculation parameters.The verification on the computation efficiency as well as accuracy of the proposed algorithm indicates that it meets the requirement of online optimisation.Originality/value–Most existing studies optimised energy-efficient train timetable or train control strategies through an offline process,which has a defect in coping with the disturbance or delays effectively and promptly during real-time train operation.This paper studies an online optimisation of cooperative train control based on the rolling optimisation idea,where energy-efficient train operation can be realised once train running time is determined,thus mitigating the impact of unpredictable operation situations on the energy-saving performance of trains.
基金Sponsored by Projects of International Cooperation and Exchange of the National Natural Science Foundation of China(Grant No.51561135003)Key Project of National Natural Science Foundation of China(Grant No.51338003)
文摘Metro system has experienced the global rapid rise over the past decades. However,few studies have paid attention to the evolution in system usage with the network expanding. The paper's main objectives are to analyze passenger flow characteristics and evaluate travel time reliability for the Nanjing Metro network by visualizing the smart card data of April 2014,April 2015 and April 2016. We performed visualization techniques and comparative analyses to examine the changes in system usage between before and after the system expansion. Specifically,workdays,holidays and weekends were specially segmented for analysis.Results showed that workdays had obvious morning and evening peak hours due to daily commuting,while no obvious peak hours existed in weekends and holidays and the daily traffic was evenly distributed. Besides,some metro stations had a serious directional imbalance,especially during the morning and evening peak hours of workdays. Serious unreliability occurred in morning peaks on workdays and the reliability of new lines was relatively low,meanwhile,new stations had negative effects on exiting stations in terms of reliability. Monitoring the evolution of system usage over years enables the identification of system performance and can serve as an input for improving the metro system quality.
基金supported by the National Natural Science Foundation of China(Grant No.42007416)the Key R&D Program of the Ministry of Science and Technology of China(Grant No.2024YFC3013303)the Research Grants Council(RGC)of Hong Kong Special Administrative Region Government of China(Grant Nos.E-PolyU501/24,T22-607/24-N).
文摘Floods have become increasingly destructive with climate change,resulting in the inundation of urban metro systems.This study complied with global data on flooded metro lines in recent decades.Based on these data,a framework incorporating machine learning(ML)with geographic information system(GIS)was developed to predict flood susceptibility in urban metro systems.To address the scarcity of subway flooding data,this study proposed a novel approach to generate a database for training and testing using ML and GIS.The 7.20 flood event in Zhengzhou,China,was analyzed as a case study.The optimal ML model was selected by comparing predicted flood states with recorded flooded metro stations.Flood susceptibility for the Zhengzhou metro system under future extreme rainfall scenarios was then predicted.Results demonstrated that the number of flooded stations and their flood susceptibility increased with rainfall intensity.These findings highlight the scale and vulnerability of metro systems,providing critical insights for developing resilient underground infrastructure.
基金supported by National Natural Science Foundation of China(No.U2166212)。
文摘Stray currents from DC metro systems intrude into the grounded neutrals of large power transformers,posing a major threat to the differential relay protection of transformer.In this paper,the performance of harmonic blocking based differential relay protection considering neutral stray currents(NSCs)from DC metro systems is thoroughly investigated.The findings reveal that relays may fail to clear internal faults in some scenarios because they are blocked due to NSC-induced harmonic currents.To improve the reliability of differential relay protection,a method for preventing incorrect operation is proposed using a skewness-based criterion to detect the presence of NSCs.Then,the relay is unblocked when an internal fault is simultaneously detected by the novel internal fault detection block.The proposed method is resistant to current transformer saturation and accounts for NSC fluctuations.Various time-domain simulations conducted in PSCAD/EMTDC verify the effectiveness of the proposed method.
基金supported by the China Scholarship Council(No.202406260166).
文摘As an integral component of modern urban transportation,metro systems have significantly contributed to alleviating urban traffic congestion and reducing carbon emissions.However,concerns about air quality in its confined environment,particularly the pollution by BTEX(benzene,toluene,ethylbenzene,and xylene),are growing.This study takes the Chengdu metro system as a case to evaluate the concentrations of BTEX and their potential health impacts on the public.Sampling was conducted in metro stations,carriages,and tunnels.The study found that the BTEX pollution levels in the metro system were 7.85±3.03µg/m^(3) in summer and 8.44±3.38µg/m^(3) in autumn,with toluene and xylene being the highest concentrations.No significant differences were observed between the halls and platforms,interchanges and non-interchanges,off peak and evening peaks in carriages,or in-service and off-service in tunnels.However,seasonal variations were pronounced.Health risk assessments indicated that while non-cancer risks were negligible,cancer risks in both summer and autumn(excluding passengers)exceeded the acceptable threshold of 1×10^(-6),potentially posing health threats to long-term exposed populations,particularly metro workers.This study provides a scientific basis for air quality management within metro systems and highlights the need for regulatory bodies to pay further attention to air quality issues,promoting the formulation and implementation of relevant control measures to protect the health and safety of passengers and metro workers.
基金support for this paper by the National Key R&D Program of China(Grant No.2021YFC2600504)the National Natural Science Foundation of China(Grant No.72174104).
文摘This paper explores the challenges of controlling complex metro systems,which are influenced by uncertain and uncontrollable large passenger flow impacts.Traditionally,flow-limiting measures during peak periods have been based on experience rather than scientific theory.To bridge this gap,we introduce a novel network analysis method inspired by control centrality theory.This approach assesses the impact of traffic loads from single or multiple sources on any node within the metro network.Our method provides a scientific basis for operators to develop policies for managing overloaded traffic,enhancing both safety and efficiency in metro system operations.
基金financially supported by National Natural Science Foundation of China(52408106).
文摘Metro systems play a crucial role in enhancing the urban economy,but the serious dust pollution during its construction poses a significant threat to the health of workers.Widely used for dust control in metro systems,the current forced ventilation technology is characterized by low dust control efficiency.In this study,an innovative arc device with efficient dust control and convenient application was proposed based on the forced ventilation.Subsequently,the orthogonal experimental method was adopted to explore the effects of air supply outlet position(L),air supply volume(Q),and air supply mode(M)on the airflow-dust distribution characteristics.The results indicated that compared with the traditional forced ventilation,the application of arc device can shorten the safe entry time after blasting operations by 9.9%–32.1%within the air supply volume of 804–1876 m3/min,effectively improving the construction efficiency and reducing the construction costs.In other words,the arc device can achieve the same dust control requirements with a smaller air supply volume,which improves the engineering applicability of forced ventilation in long-distance tunnel excavation while reducing ventilation energy consumption.Furthermore,the theoretical optimal combination scheme(L=35 m,Q=1876 m3/min,M=arc device)composed of the optimal levels of three factors achieved a 13%improvement in dust control compared to the experimental optimal combination scheme determined by the minimum safe entry time.This study can provide new strategies for improving the dust control performance of forced ventilation used in metro system construction.
基金supported by a grant from the National Social Science Fund of China(No.20BGL301).
文摘During special events,some metro lines and stations may alter their first train schedules to an earlier time,while others remain unchanged.These adjustments can result in longer transfer waiting times for passengers,negatively impacting the overall quality of metro services.Thus,optimizing first train schedules is essential,as it directly influences morning service quality and passengers’ability to complete their journeys.However,this task is complicated by the elastic nature of passenger flow and inflexibility of published sched-ules.To tackle this issue,this paper presents a mathematical model that captures the elas-tic demand for early-morning travel.It also proposes an optimization approach for reducing both the adjustment costs of first-train schedule changes and transfer redun-dancy time throughout the network.By applying linearization techniques,the problem is reformulated into a linear programming model.The effectiveness of this method is demon-strated through a case study of the Shenzhen metro,which showed a 9.1%reduction in average transfer redundancy time by adjusting the departure times of first trains on two lines and at ten stations during a special event.These results indicate that for metro sys-tems with fixed first train schedules,carefully adjusting departure times at specific stations can effectively accommodate early-morning passenger needs and improve the overall quality of morning services.
基金supported by the National Natural Science Foundation of China(grant number 71890972/71890970,72171020)the Fonds de Recherche du Quebec-Societe et Culture(FRQSC)under the NSFC-FRQSC Research Program on Smart Cities and Big Data+1 种基金the Canada Foundation for Innovation(CFI)John R.Evans Leaders Fundthe 111 Project(grant number B20071).
文摘Metro systems in megacities such as Beijing,Shenzhen,and Guangzhou are under great passenger demand pressure.During peak hours,it is common to see oversaturated conditions(i.e.,passenger demand exceeds network capacity)and a popular control intervention is to restrict the entering rate by setting up out-of-station queueing with crowd control barriers.The out-of-station waiting can make up a substantial proportion of total travel time but is often ignored in the literature.Quantifying out-of-station waiting is important to evaluating the social benefit and cost of metro services;however,out-of-station waiting is difficult to estimate because it leaves no trace in smart card transactions of metros.In this study,we estimate the out-of-station waiting time by leveraging the information from a small group of transfer passengers—those who transfer from nearby bus routes to the metro station.Based on the transfer interval of this small group,we infer the out-of-station waiting time for all passengers by a Gaussian Process regression and then use the estimated out-of-station waiting time to build queueing diagrams.We apply our method to the Tiantongyuan North station of Beijing metro;results show that the maximum out-of-station waiting time can reach 15 min,and the maximum queue length can be over 3000 passengers.We find out-of-station waiting can cause significant travel costs and thus should be considered in analyzing transit performance,mode choice,and social benefits.To the best of our knowledge,this paper is the first quantitative study for out-of-station waiting time.
基金We would like to thank all the Egis team who took the time to help and dedicate their time in the development of the concept of the multifunctional metro,the Sytral for their support during our researches,and all the people interviewed at the Grand Lyon for their time,all the information they gave us about urban needs in Lyon and their wise advises on the appropriate functions to investigate.We also thank ESTP for their help in the definition and the development of the methodology to develop multifunctional infrastructures.
文摘Several studies,from both the private sector(McKinsey,Engie,and EY)and international organizations(OECD,World Bank,and IMF),have shown that urban population in cities will grow in the coming decades.This growth implies an increased pressure on all urban networks-transporting people,goods,water,waste,electricity,information,heat,and so on.These functions are executed by urban infrastructures entailing huge investments.We have dedicated our research to the optimization of infrastructures and more precisely of metro systems to offer global solutions to fulfill city needs-the multifunctional metro.The innovative multifunctional metro system incorporates several other urban networks—optical fiber,high-voltage electric cables,water and sewage pipes,geothermal piles,pneumatic systems,merchandise shuttles,and many others depending on the context of each project.The aim of the multifunctional metro is to meet several needs of cities with one common infrastructure.Adding a function to a system increases its complexity.For this reason,we focus our research on the application of methods that allow better management of the complexity:systems engineering applied to infrastructures.In the first part of the paper,we will present a benchmark of multipurpose infrastructures across the world and the benefits of such a system for cities.In the second part,we will present and illustrate the concept of the multifunctional metro.Next,we will present the method based on systems engineering to analyse multifunctional systems.Finally,the concept of a multifunctional metro is illustrated with a case study on the future fifth metro line of Lyon,France.In conclusion,we will discuss the current barriers for the development of multifunctional infrastructures.
基金funded by Project supported by the Natural Science Foundation of Gansu Province,China(Grant No.22JR5RA318).
文摘In order to fully utilize the regenerative braking energy of metro trains and stabilize the metro DC traction busbar voltage,a hybrid regenerative braking energy recovery system with a dual-mode power management strategy is proposed.Firstly,the construction of the hybrid regenerative braking energy recovery system is explained.Then,based on the power demand of low-voltage load in metro stations,a dual-mode power management strategy is proposed to allocate the reference power of each system according to the different working conditions,and the control methods of each system are set.Finally,the correctness and effectiveness of the dual-mode strategy are verified through simulation,and the proposed braking energy utilization scheme is compared with other singleform utilization schemes.The results illustrate that the hybrid system with the dual-mode strategy can effectively recycle the regenerative braking energy of metro train and inhibit the busbar voltage fluctuation;the proposed braking energy utilization scheme has certain advantages on energy recovery and DC bus voltage stabilization compared with other single-form schemes;the proposed power management strategy can correctly allocate the reference power of each system with a lower construction cost.
文摘Construction management innovation system of metro in China is put forward in this paper. Guidelines,objective system,new management ideas and contents of this construction management innovation system are set forth particularly. The construction management innovation system of metro can meet needs of building harmonious and economized society and realizing sustainable development in China,it is also an important part of science & technology innovation system.
文摘On the basis of analyzing the influencing factors and harmfulness of stray current, and discussing the existing problems of monitoring and prevention system for stray current, the integrated monitoring and prevention system for stray current in metro was developed. A net system of distributed computers for monitoring was set up. It can monitor the distribution of stray current in metro and the corrosion of the metal structure in the whole line. According to the situation of monitoring it can also control the drainage of its tank to reach the best effect and eliminate the negative effect of polarity drainage. By using the new type unilateral electric device, the problem of burning the rail by electric arc can be avoided. The unilateral electric device can be connected with the monitoring net system directly to realize the monitor in line and improve the reliability of the device.
基金Supported by National Natural Science Foundation of China(Grant No.11772230)。
文摘The mechanism of rail corrugation remains unclear,and the research methods require improvement.The vibration characteristics represent the system's external manifestations,but a comprehensive analysis is still lacking.Taking the vibration characteristics of the wheel-rail system as a starting point,this study investigates the formation mechanisms of rail corrugation on measured metro lines.The line sections included both steel spring floating slab tracks and long sleeper embedded tracks.First,the wavelength and frequency attributes of rail corrugation were obtained through field measurements.Then,referencing line conditions,three-dimensional finite element numerical models were established,frequency response calculations were performed,and the relationship between the vibration responses of the wheel-rail system and rail corrugation was analyzed.Finally,a parameter sensitivity analysis of the wheel-rail system was conducted to control the further development of rail corrugation.The results show distinct corrugation phenomena on both inner and outer rails in the measured sections.The characteristic wavelengths of inner and outer rail corrugation on the steel spring floating slab track are 34 mm and 59 mm,respectively,and the characteristic wavelengths of inner and outer rail corrugation on the long sleeper embedded track are 46 mm and 47 mm,respectively.The frequency response analysis indicates that the numerical results exhibit eigenfrequencies close to the passing frequencies of the measured corrugations.The formation mechanism of inner rail corrugation on the steel spring floating slab track is attributed to the third-order bending vibration of the wheelset,which leads to the generation of inner rail corrugation.In contrast,the formation mechanism of outer rail corrugation is attributed to the lateral bending vibration of the outer rail.For the long sleeper embedded track,inner rail corrugation is generated by the lateral bending vibration of the inner rail,while outer rail corrugation results from the lateral bending vibration of the outer rail.Appropriate adjustments to the fastener's vertical and lateral stiffness,as well as the steel spring's vertical and lateral stiffness,can shift the rail corrugation eigenfrequencies,thereby inhibiting the development of corrugation with the original wavelength.Changes in other parameters have no effect on the rail corrugation eigenfrequencies and only influence the development speed of corrugation with the original wavelength.This research effectively elucidates the cause of rail corrugation from the system vibration perspective and provides a valuable complement to the corrugation analysis method.
基金support extended by the Joint Funds of Beijing Municipal Natural Science Foundation and Fengtai Rail Transit Frontier Research(Grant No.L211006)the Fundamental Research Funds for the Central Universities(Science and technology leading talent team project,Grant No.2022JBXT010)+1 种基金the Fundamental Research Funds for the Central Universities(Grant No.2023YJS052)the National Natural Science Foundation of China(Grant No.52308426)。
文摘Investigations into rail corrugation within metro systems have traditionally focused on specific mechanisms,thereby limiting the generalizability of proposed theories.Understanding the commonalities in rail corrugation across diverse metro lines remains pivotal for elucidating its underlying mechanisms.The present study conducted extensive field surveys and tracking tests across 14 Chinese metro lines.By employing t-distributed stochastic neighbor embedding(t-SNE)for dimensional reduction and employing the unsupervised clustering algorithm DBSCAN,the research redefines the classification of metro rail corrugation based on characteristic information.The analysis encompassed spatial distribution and temporal evolution of this phenomenon.Findings revealed that floating slab tracks exhibited the highest proportion of rail corrugation at 47%.Notably,ordinary monolithic bed tracks employing damping fasteners were more prone to inducing rail corrugation.Corrugation primarily manifested in curve sections with radii between 300 and 500 m,featuring ordinary monolithic bed track and steel-spring floating slab track structures,with wavelengths typically between 30 and 120 mm.Stick–slip vibrations of the wheel–rail system maybe led to short-wavelength corrugations(40–60 mm),while longer wavelengths(200–300 mm)exhibited distinct fatigue damage characteristics,mainly observed in steel-spring floating slab tracks and small-radius curve sections of ordinary monolithic bed tracks and ladder sleeper tracks.A classification system comprising 57 correlated features categorized metro rail corrugation into four distinct types.These research outcomes serve as critical benchmarks for validating various theories pertaining to rail corrugation formation.
文摘Power supply is one of the key components to support subway operation, and subway projects usually have the characteristics of low pollution and high efficiency. The number of vehicles in our country is increasing, and the traffic pressure is increasing. Under such a condition, the construction of subway has effectively shared some of the traffic pressure, meeting the needs of urban traffic development as much as possible. If you want to make the subway run normally, then the power supply should be continuously reliable and stable. There are three power supply methods for subway, namely centralized power supply, decentralized power supply and hybrid power supply. In the process of implementation in reality, scientific selection and application must be carried out according to the technical requirements.
文摘At this stage, the rapid social progress, the development of China's subway engineering construction has also been improved. Relevant research points out that the future metro power dispatching information management system should have high precision and powerful real-time monitoring function, which can accurately locate the fault location while carrying out early warning. In addition, through the above process, the related failure events can be specially handled to form the whole process monitoring of the whole system. In the process of establishing the knowledge base, it belongs to the reference process of historical experience information, so as to improve the efficiency of solving power failure and meet the development needs of the whole system.
基金funded by the Institution of Eminence,with the University of Delhi cited as IoE/2024-25/12/FRP.
文摘This study offers valuable insights into the relationship between metro ridership patterns and the spatial transformations around Delhi Metro stations,underscoring the role of mass transit infrastructure in shaping urban land use and ecosystem landscapes.The primary objective is to assess how high-ridership metro stations can positively influence urban development,particularly regarding socio-economic and ecological dimensions.Integrating primary survey data with ridership statistics from the Delhi Metro Rail Corporation(DMRC),the research identifies key interchange stations,such as Kashmere Gate and Rajiv Chowk,which exhibit substantial passenger volumes.Utilising GIS-based spatial analysis and remote sensing techniques,land use changes within a 500-meter buffer zone around these stations are considered,focusing on built-up areas,green cover,and open space availability.Time-series satellite imagery generates comparative maps illustrating land use changes pre-and post-introduction of metro services.The analysis reveals that high-ridership stations are linked to significant commercial densification,particularly near Rajiv Chowk,with a p-value of 0.172.Conversely,peripheral stations like Dwarka Sector 21 indicate residential growth trends,with a p-value of 0.087 for residential areas.Importantly,two land use categories—Green Space(t=-2.33,p=0.045)and Open Space(t=3.57,p=0.006)—show statistically significant reductions,highlighting the ecological impacts of metro infrastructure.The findings suggest that metro systems can promote commercial clustering in urban centres while fostering residential growth in surrounding areas.Overall,the study highlights the potential of metro systems to enhance accessibility,reshape urban ecosystems,and encourage the development of compact urban forms.The implications for urban planning advocate for transit-oriented development(TOD)as a strategic approach to manage growth,minimise sprawl,and ensure sustainable and inclusive development.
文摘Background:Shift-based occupations have been consistently linked to adverse psychological outcomes;however,limited research has examined how work schedule type and physical activity are jointly associated with mental health and job stress in public transportation employees,a population frequently exposed to irregular hours and safety-critical responsibilities.This study investigated the associations between work schedule type and physical activity with mental health indicators and job stress among Seoul Metro employees.Methods:A cross-sectional survey was administered to 298 full-time male employees of Seoul Metro.Participants were categorized by work schedule(shift vs.regular)and physical activity level(regular,irregular,none)following American College of Sports Medicine(ACSM)guidelines.Mental health(sleep disturbance,depression,anxiety,loneliness)was assessed using validated binary indicators,and job stress was measured with the Korean Occupational Stress Scale–Short Form(KOSS-SF).Group differences were analyzed using chi-square tests,t-tests,and one-way ANOVA with effect sizes,and binary logistic and multiple regression analyses were conducted to identify predictors.Results:Shift workers reported significantly higher sleep disturbance and anxiety compared to regular daytime workers(p<0.05).Employees who participated in regular physical activity had lower odds of sleep disturbance and depression(p<0.05)and showed lower job stress scores compared with inactive workers.Work schedule type and physical activity were independently associated with mental health and job stress among transit employees.Conclusion:These findings underscore the dual influence of work schedule and physical activity on the psychological and occupational well-being of public transit employees.Promoting regular physical activity may buffer occupational stress among employees engaged in shift-based work.Workplace interventions that support physical activity participation and improve shift planning may enhance employee well-being.
