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
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
As a key mode of transportation, urban metro networks have significantly enhanced urban traffic environments and travel efficiency, making the identification of critical stations within these networks increasingly ess...As a key mode of transportation, urban metro networks have significantly enhanced urban traffic environments and travel efficiency, making the identification of critical stations within these networks increasingly essential. This study presents a novel integrated topological-functional(ITF) algorithm for identifying critical nodes, combining topological metrics such as K-shell decomposition, node information entropy, and neighbor overlapping interaction with the functional attributes of passenger flow operations, while also considering the coupling effects between metro and bus networks. Using the Chengdu metro network as a case study, the effectiveness of the algorithm under different conditions is validated.The results indicate significant differences in passenger flow patterns between working and non-working days, leading to varying sets of critical nodes across these scenarios. Moreover, the ITF algorithm demonstrates a marked improvement in the accuracy of critical node identification compared to existing methods. This conclusion is supported by the analysis of changes in the overall network structure and relative global operational efficiency following targeted attacks on the identified critical nodes. The findings provide valuable insight into urban transportation planning, offering theoretical and practical guidance for improving metro network safety and resilience.展开更多
With the increasing adoption of intelligent operation and maintenance technologies in urban rail transit,most maintenance systems have been equipped with fault diagnosis modules targeting key components of metro vehic...With the increasing adoption of intelligent operation and maintenance technologies in urban rail transit,most maintenance systems have been equipped with fault diagnosis modules targeting key components of metro vehicles.However,the integration between engineering-level diagnostic algorithms and advanced academic research remains limited.Two major challenges hinder vibration-based fault diagnosis under real-world operating conditions:the complex noise and interference caused by wheel-rail coupling and the typically weak expression of fault features.Considering the widespread application of wavelet transform in noise reduction and the maturity of ensemble empirical mode decomposition(EEMD)in handling nonlinear and non-stationary signals without parameter tuning,this study proposes a diagnostic method that combines wavelet threshold denoising with EEMD.The method was applied to bearing vibration signals collected from an operational subway line.The diagnostic results were consistent with actual disassembly findings,demonstrating the effectiveness and practical value of the proposed approach.展开更多
This study explores the factors influencing metro passengers’ arrival volume in Wuhan, China, and Lagos, Nigeria, by examining weather, time of day, waiting time, travel behavior, arrival patterns, and metro satisfac...This study explores the factors influencing metro passengers’ arrival volume in Wuhan, China, and Lagos, Nigeria, by examining weather, time of day, waiting time, travel behavior, arrival patterns, and metro satisfaction. It addresses a significant research gap in understanding metro passengers’ dynamics across cultural and geographical contexts. It employs questionnaires, field observations, and advanced data analysis techniques like association rule mining and neural network modeling. Key findings include a correlation between rainy weather, shorter waiting times, and higher arrival volumes. Neural network models showed high predictive accuracy, with waiting time, metro satisfaction, and weather being significant factors in Lagos Light Rail Blue Line Metro. In contrast, arrival patterns, weather, and time of day were more influential in Wuhan Metro Line 5. Results suggest that improving metro satisfaction and reducing waiting times could increase arrival volumes in Lagos Metro while adjusting schedules for weather and peak times could optimize flow in Wuhan Metro. These insights are valuable for transportation planning, passenger arrival volume management, and enhancing user experiences, potentially benefiting urban transportation sustainability and development goals.展开更多
The land subsidence characteristics in Shanghai were constantly developing with the change of groundwater level in the process of urban development,and had different effects on the deformation of metro tunnels buried ...The land subsidence characteristics in Shanghai were constantly developing with the change of groundwater level in the process of urban development,and had different effects on the deformation of metro tunnels buried in deep soft soil layers.In this study,the long time series field monitoring data obtained by levelling and stratification extensometer methods was analyzed,and the coupling deformation mechanism of geological stratification and metro tunnel in deep quaternary coastal areas for different periods and scenarios was revealed.The results showed that with the rapid rise of the groundwater level in Shanghai since 2005,the deep sedimentary strata gradually rebound,resulting in the universal rebound of underground metro tunnel.The deformation trends of soil layers and metro tunnel structure were inconsistent with the regional land subsidence due to different control factors.For metro lines built in different periods,the tunnel displacement was basically controlled by the deformation of sedimentary strata below the tunnel structure.The coupling deformation of geological stratification and metro tunnel structure in the deep Quaternary sedimentary area can be described in three conceptual calculation models:inverse settlement model,extrusion model and counteract model.The hysteresis effects when the increase of water volume transformed to the rise of groundwater level and the soil layer deformation driven by rising water level were discussed.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
To understand the mechanical response pattern of the existing structure and ground due to the construction of metro tunnels underneath,the finite difference method is adopted to study the torsional deformation and str...To understand the mechanical response pattern of the existing structure and ground due to the construction of metro tunnels underneath,the finite difference method is adopted to study the torsional deformation and stress variation of the existing structure and the effect of underground carriageway structures on the surface subsidence.The curves of the maximum differential subsidence,torsion angle,and distortion of the cross-section of the existing structure show two peaks in succession during traversing of two metro tunnels beneath it.The torsion angle of the existing structure changes when the two tunnels traverse beneath it in opposite directions.The first traversing of the shield tunnel mainly induces the magnitude variation in torsional deformation of the existing structure,but the second traversing of the subsurface tunnel may cause a dynamic change in the magnitude and form of torsional deformation in the existing structure.The shielding effect can reduce the surface subsidence caused by metro tunnel excavation to a certain extent,and the development trend of subsidence becomes slower as the excavation continues.展开更多
The advent of the big data era has provided many types of transportation datasets,such as metro smart card data,for studying residents’mobility and understanding how their mobility has been shaped and is shaping the ...The advent of the big data era has provided many types of transportation datasets,such as metro smart card data,for studying residents’mobility and understanding how their mobility has been shaped and is shaping the urban space.In this paper,we use metro smart card data from two Chinese metropolises,Shanghai and Shenzhen.Five metro mobility indicators are introduced,and association rules are established to explore the mobility patterns.The proportion of people entering and exiting the station is used to measure the jobs-housing balance.It is found that the average travel distance and duration of Shanghai passengers are higher than those of Shenzhen,and the proportion of metro commuters in Shanghai is higher than that of Shenzhen.The jobs-housing spatial relationship in Shenzhen based on metro travel is more balanced than that in Shanghai.The fundamental reason for the differences between the two cities is the difference in urban morphology.Compared with the monocentric structure of Shanghai,the polycentric structure of Shenzhen results in more scattered travel hotspots and more diverse travel routes,which helps Shenzhen to have a better jobs-housing balance.This paper fills a gap in comparative research among Chinese cities based on transportation big data analysis.The results provide support for planning metro routes,adjusting urban structure and land use to form a more reasonable metro network,and balancing the jobs-housing spatial relationship.展开更多
Purpose–The principle of infinite life design currently directs fatigue resistance strategies for metro car bodies.However,this principle might not fully account for the dynamic influence of operational loads and the...Purpose–The principle of infinite life design currently directs fatigue resistance strategies for metro car bodies.However,this principle might not fully account for the dynamic influence of operational loads and the inevitable presence of defects.This study aims to integrate methods of service life estimation and residual life assessment,which are based on operational loads,into the existing infinite life verification framework to further ensure the operational safety of subway trains.Design/methodology/approach–Operational loads and fatigue loading spectra were determined through the field test.The material test was conducted to investigate characteristics of the fracture toughness and the crack growth rate.The fatigue strength of the metro car body was first verified using the finite element method and Moore–Kommers–Japer diagrams.The service life was then estimated by applying the Miner rule and high-cycle fatigue curves in a modified form of the Basquin equation.Finally,the residual life was assessed utilizing a fracture assessment diagram and a fitted curve of crack growth rate adhered to the Paris formula.Findings–Neither the maximum utilization factor nor the cumulative damage exceeds the threshold value of 1.0,the metro car body could meet the design life requirement of 30 years or 6.6 million km.However,three out of five fatigue key points were significantly influenced by the operational loads,which indicates that a single fatigue strength verification cannot achieve the infinite life design objective of the metro car body.For a projected design life of 30 years,the tolerance depth is 12.2 mm,which can underscore a relatively robust damage tolerance capability.Originality/value–The influence of operational loads on fatigue life was presented by the discrepancy analysis between fatigue strength verification results and service life estimation results.The fracture properties of butt-welded joints were tested and used for the damage tolerance assessment.The damage tolerance life can be effectively related by a newly developed equation in this study.It can be a valuable tool to provide the theoretical guidance and technical support for the structural improvements and maintenance decisions of the metro car body.展开更多
Purpose – The volume of passenger traffic at metro transfer stations serves as a pivotal metric for theorchestration of crowd flow management. Given the intricacies of crowd dynamics within these stations andthe recu...Purpose – The volume of passenger traffic at metro transfer stations serves as a pivotal metric for theorchestration of crowd flow management. Given the intricacies of crowd dynamics within these stations andthe recurrent instances of substantial passenger influxes, a methodology predicated on stochastic processesand the principle of user equilibrium is introduced to facilitate real-time traffic flow estimation within transferstation streamlines.Design/methodology/approach – The synthesis of stochastic process theory with streamline analysisengenders a probabilistic model of intra-station pedestrian traffic dynamics. Leveraging real-time passengerflow data procured from monitoring systems within the transfer station, a gradient descent optimizationtechnique is employed to minimize the cost function, thereby deducing the dynamic distribution of categorizedpassenger flows. Subsequently, adhering to the tenets of user equilibrium, the Frank–Wolfe algorithm isimplemented to allocate the intra-station categorized passenger flows across various streamlines, ascertainingthe traffic volume for each.Findings – Utilizing the Xiaozhai Station of the Xi’an Metro as a case study, the Anylogic simulation softwareis engaged to emulate the intra-station crowd dynamics, thereby substantiating the efficacy of the proposedpassenger flow estimation model. The derived solutions are instrumental in formulating a crowd controlstrategy for Xiaozhai Station during the peak interval from 17:30 to 18:00 on a designated day, yielding crowdmanagement interventions that offer insights for the orchestration of passenger flow and operationalgovernance within metro stations.Originality/value – The construction of an estimation methodology for the real-time streamline traffic flowaugments the model’s dataset, supplanting estimated values derived from surveys or historical datasets withreal-time computed traffic data, thereby enhancing the precision and immediacy of crowd flow managementwithin metro stations.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
This study applied the interaction of social vulnerability and hazard to assess flood risk in three urbanized areas within the Pasig-Marikina-Laguna-Lake catchment:Manila,Marikina,and Parañaque in Metro Manila,Ph...This study applied the interaction of social vulnerability and hazard to assess flood risk in three urbanized areas within the Pasig-Marikina-Laguna-Lake catchment:Manila,Marikina,and Parañaque in Metro Manila,Philippines.This study examined risk patterns across different flood return periods(5,50,and 100 years)in these urban river environments and provided both city-wide and localized risk assessments.The social vulnerability to flood index(SVFI)was calculated using socioeconomic indicators,while the hazard index was derived from flood depth categories.Results show that city-level risk indices are low to moderate,with Marikina consistently having the highest risk,followed by Manila and Parañaque.However,localized assessments reveal high-risk areas within cities,with Manila being the most vulnerable to frequent floods(5-year return period)and Marikina to less frequent but extreme events(50-and 100-year return periods).Parañaque maintains the lowest risk profile across all scenarios.This study highlights the importance of considering both citywide trends and localized high-risk areas in flood risk management.It provides valuable insights for disaster management planners and policymakers,enabling the development of targeted strategies for sustainable urban river management and flood risk reduction in rapidly urbanizing river systems.The methodology presented applies to other urban areas that face similar flood risks.展开更多
Metro is an important form of public transport in Shanghai.Based on the metro card data,we conduct the cluster analysis of Shanghai metro stations according to the pattern of passenger flow changing with time.Then the...Metro is an important form of public transport in Shanghai.Based on the metro card data,we conduct the cluster analysis of Shanghai metro stations according to the pattern of passenger flow changing with time.Then the characteristics of travel time and surrounding land use are investigated for different types of stations to explore the relationship between urban land-use characteristics and travel activities reflected by passenger flow at metro stations.It is found that the passenger flow pattern of metro stations is closely related to the location conditions of stations and its surrounding land-use patterns.Based on various characteristics,285 metro stations are classified into four types,including residential-oriented stations,employmentoriented stations,employment-residence-oriented stations,and integrated functionaloriented stations,reflecting the interaction between spontaneous travel behavior and urban land-use characteristics and providing a reference for optimizing the urban functional structure and the spatial allocation of facilities.展开更多
The metro is the most efficient and convenient public transport system in modern cities. For urban core areas in China, in which the metro was built later, there was more consideration for meeting the traffic needs of...The metro is the most efficient and convenient public transport system in modern cities. For urban core areas in China, in which the metro was built later, there was more consideration for meeting the traffic needs of cities. However, there are few studies of collaborative planning for metro stations and their surrounding space. Thus, there is an urgent need to conduct research on collaborative planning for metro stations and their surrounding commercial space in urban core areas. Unlike conventional methods of integrated design of stations and cities, this paper, based on the theory of place spirit, took Chunxi Road Metro Station in Chengdu and its surrounding commercial space for example. It explored the pattern and characteristics of the place in the commercial space around the metro station, analyzed the strategies of cultural and commercial integration, as well as architecture, street, landscape and other aspects of the design method in the space, and explored the strategies of place-making and infiltration, providing a reference point for the development and place-making of the commercial space around metro stations in urban core areas.展开更多
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.
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.
基金Project supported by the National Natural Science Foundation of China (Grant No. 71971150)the Project of Research Center for System Sciences and Enterprise Development (Grant No. Xq16B05)the Fundamental Research Funds for the Central Universities of China (Grant No. SXYPY202313)。
文摘As a key mode of transportation, urban metro networks have significantly enhanced urban traffic environments and travel efficiency, making the identification of critical stations within these networks increasingly essential. This study presents a novel integrated topological-functional(ITF) algorithm for identifying critical nodes, combining topological metrics such as K-shell decomposition, node information entropy, and neighbor overlapping interaction with the functional attributes of passenger flow operations, while also considering the coupling effects between metro and bus networks. Using the Chengdu metro network as a case study, the effectiveness of the algorithm under different conditions is validated.The results indicate significant differences in passenger flow patterns between working and non-working days, leading to varying sets of critical nodes across these scenarios. Moreover, the ITF algorithm demonstrates a marked improvement in the accuracy of critical node identification compared to existing methods. This conclusion is supported by the analysis of changes in the overall network structure and relative global operational efficiency following targeted attacks on the identified critical nodes. The findings provide valuable insight into urban transportation planning, offering theoretical and practical guidance for improving metro network safety and resilience.
文摘With the increasing adoption of intelligent operation and maintenance technologies in urban rail transit,most maintenance systems have been equipped with fault diagnosis modules targeting key components of metro vehicles.However,the integration between engineering-level diagnostic algorithms and advanced academic research remains limited.Two major challenges hinder vibration-based fault diagnosis under real-world operating conditions:the complex noise and interference caused by wheel-rail coupling and the typically weak expression of fault features.Considering the widespread application of wavelet transform in noise reduction and the maturity of ensemble empirical mode decomposition(EEMD)in handling nonlinear and non-stationary signals without parameter tuning,this study proposes a diagnostic method that combines wavelet threshold denoising with EEMD.The method was applied to bearing vibration signals collected from an operational subway line.The diagnostic results were consistent with actual disassembly findings,demonstrating the effectiveness and practical value of the proposed approach.
文摘This study explores the factors influencing metro passengers’ arrival volume in Wuhan, China, and Lagos, Nigeria, by examining weather, time of day, waiting time, travel behavior, arrival patterns, and metro satisfaction. It addresses a significant research gap in understanding metro passengers’ dynamics across cultural and geographical contexts. It employs questionnaires, field observations, and advanced data analysis techniques like association rule mining and neural network modeling. Key findings include a correlation between rainy weather, shorter waiting times, and higher arrival volumes. Neural network models showed high predictive accuracy, with waiting time, metro satisfaction, and weather being significant factors in Lagos Light Rail Blue Line Metro. In contrast, arrival patterns, weather, and time of day were more influential in Wuhan Metro Line 5. Results suggest that improving metro satisfaction and reducing waiting times could increase arrival volumes in Lagos Metro while adjusting schedules for weather and peak times could optimize flow in Wuhan Metro. These insights are valuable for transportation planning, passenger arrival volume management, and enhancing user experiences, potentially benefiting urban transportation sustainability and development goals.
基金financial support provided by the Science and Technology Commission of Shanghai Municipality(grant no.22ZR1447100,21DZ1204200 and 23XD1402400).
文摘The land subsidence characteristics in Shanghai were constantly developing with the change of groundwater level in the process of urban development,and had different effects on the deformation of metro tunnels buried in deep soft soil layers.In this study,the long time series field monitoring data obtained by levelling and stratification extensometer methods was analyzed,and the coupling deformation mechanism of geological stratification and metro tunnel in deep quaternary coastal areas for different periods and scenarios was revealed.The results showed that with the rapid rise of the groundwater level in Shanghai since 2005,the deep sedimentary strata gradually rebound,resulting in the universal rebound of underground metro tunnel.The deformation trends of soil layers and metro tunnel structure were inconsistent with the regional land subsidence due to different control factors.For metro lines built in different periods,the tunnel displacement was basically controlled by the deformation of sedimentary strata below the tunnel structure.The coupling deformation of geological stratification and metro tunnel structure in the deep Quaternary sedimentary area can be described in three conceptual calculation models:inverse settlement model,extrusion model and counteract model.The hysteresis effects when the increase of water volume transformed to the rise of groundwater level and the soil layer deformation driven by rising water level were discussed.
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.
基金National Natural Science Foundation of China,Grant/Award Numbers:51878060,52078046。
文摘To understand the mechanical response pattern of the existing structure and ground due to the construction of metro tunnels underneath,the finite difference method is adopted to study the torsional deformation and stress variation of the existing structure and the effect of underground carriageway structures on the surface subsidence.The curves of the maximum differential subsidence,torsion angle,and distortion of the cross-section of the existing structure show two peaks in succession during traversing of two metro tunnels beneath it.The torsion angle of the existing structure changes when the two tunnels traverse beneath it in opposite directions.The first traversing of the shield tunnel mainly induces the magnitude variation in torsional deformation of the existing structure,but the second traversing of the subsurface tunnel may cause a dynamic change in the magnitude and form of torsional deformation in the existing structure.The shielding effect can reduce the surface subsidence caused by metro tunnel excavation to a certain extent,and the development trend of subsidence becomes slower as the excavation continues.
基金National Key R&D Program of China(No.2019YFB2103102)Hong Kong Polytechnic University(No.CD06,P0042540)。
文摘The advent of the big data era has provided many types of transportation datasets,such as metro smart card data,for studying residents’mobility and understanding how their mobility has been shaped and is shaping the urban space.In this paper,we use metro smart card data from two Chinese metropolises,Shanghai and Shenzhen.Five metro mobility indicators are introduced,and association rules are established to explore the mobility patterns.The proportion of people entering and exiting the station is used to measure the jobs-housing balance.It is found that the average travel distance and duration of Shanghai passengers are higher than those of Shenzhen,and the proportion of metro commuters in Shanghai is higher than that of Shenzhen.The jobs-housing spatial relationship in Shenzhen based on metro travel is more balanced than that in Shanghai.The fundamental reason for the differences between the two cities is the difference in urban morphology.Compared with the monocentric structure of Shanghai,the polycentric structure of Shenzhen results in more scattered travel hotspots and more diverse travel routes,which helps Shenzhen to have a better jobs-housing balance.This paper fills a gap in comparative research among Chinese cities based on transportation big data analysis.The results provide support for planning metro routes,adjusting urban structure and land use to form a more reasonable metro network,and balancing the jobs-housing spatial relationship.
基金the CRRC Zhuzhou Locomotive Co.,Ltd.and Shanghai Railway Certification(Group)Co.,Ltd.This research was funded by the Major Research Project of CRRC(No.2022CYY007 and No.2020CCA094).
文摘Purpose–The principle of infinite life design currently directs fatigue resistance strategies for metro car bodies.However,this principle might not fully account for the dynamic influence of operational loads and the inevitable presence of defects.This study aims to integrate methods of service life estimation and residual life assessment,which are based on operational loads,into the existing infinite life verification framework to further ensure the operational safety of subway trains.Design/methodology/approach–Operational loads and fatigue loading spectra were determined through the field test.The material test was conducted to investigate characteristics of the fracture toughness and the crack growth rate.The fatigue strength of the metro car body was first verified using the finite element method and Moore–Kommers–Japer diagrams.The service life was then estimated by applying the Miner rule and high-cycle fatigue curves in a modified form of the Basquin equation.Finally,the residual life was assessed utilizing a fracture assessment diagram and a fitted curve of crack growth rate adhered to the Paris formula.Findings–Neither the maximum utilization factor nor the cumulative damage exceeds the threshold value of 1.0,the metro car body could meet the design life requirement of 30 years or 6.6 million km.However,three out of five fatigue key points were significantly influenced by the operational loads,which indicates that a single fatigue strength verification cannot achieve the infinite life design objective of the metro car body.For a projected design life of 30 years,the tolerance depth is 12.2 mm,which can underscore a relatively robust damage tolerance capability.Originality/value–The influence of operational loads on fatigue life was presented by the discrepancy analysis between fatigue strength verification results and service life estimation results.The fracture properties of butt-welded joints were tested and used for the damage tolerance assessment.The damage tolerance life can be effectively related by a newly developed equation in this study.It can be a valuable tool to provide the theoretical guidance and technical support for the structural improvements and maintenance decisions of the metro car body.
文摘Purpose – The volume of passenger traffic at metro transfer stations serves as a pivotal metric for theorchestration of crowd flow management. Given the intricacies of crowd dynamics within these stations andthe recurrent instances of substantial passenger influxes, a methodology predicated on stochastic processesand the principle of user equilibrium is introduced to facilitate real-time traffic flow estimation within transferstation streamlines.Design/methodology/approach – The synthesis of stochastic process theory with streamline analysisengenders a probabilistic model of intra-station pedestrian traffic dynamics. Leveraging real-time passengerflow data procured from monitoring systems within the transfer station, a gradient descent optimizationtechnique is employed to minimize the cost function, thereby deducing the dynamic distribution of categorizedpassenger flows. Subsequently, adhering to the tenets of user equilibrium, the Frank–Wolfe algorithm isimplemented to allocate the intra-station categorized passenger flows across various streamlines, ascertainingthe traffic volume for each.Findings – Utilizing the Xiaozhai Station of the Xi’an Metro as a case study, the Anylogic simulation softwareis engaged to emulate the intra-station crowd dynamics, thereby substantiating the efficacy of the proposedpassenger flow estimation model. The derived solutions are instrumental in formulating a crowd controlstrategy for Xiaozhai Station during the peak interval from 17:30 to 18:00 on a designated day, yielding crowdmanagement interventions that offer insights for the orchestration of passenger flow and operationalgovernance within metro stations.Originality/value – The construction of an estimation methodology for the real-time streamline traffic flowaugments the model’s dataset, supplanting estimated values derived from surveys or historical datasets withreal-time computed traffic data, thereby enhancing the precision and immediacy of crowd flow managementwithin metro stations.
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TOKYO METROPOLITAN GOVERNMENT ADVANCED RESEARCH,Grant/Award Number:R4-2。
文摘This study applied the interaction of social vulnerability and hazard to assess flood risk in three urbanized areas within the Pasig-Marikina-Laguna-Lake catchment:Manila,Marikina,and Parañaque in Metro Manila,Philippines.This study examined risk patterns across different flood return periods(5,50,and 100 years)in these urban river environments and provided both city-wide and localized risk assessments.The social vulnerability to flood index(SVFI)was calculated using socioeconomic indicators,while the hazard index was derived from flood depth categories.Results show that city-level risk indices are low to moderate,with Marikina consistently having the highest risk,followed by Manila and Parañaque.However,localized assessments reveal high-risk areas within cities,with Manila being the most vulnerable to frequent floods(5-year return period)and Marikina to less frequent but extreme events(50-and 100-year return periods).Parañaque maintains the lowest risk profile across all scenarios.This study highlights the importance of considering both citywide trends and localized high-risk areas in flood risk management.It provides valuable insights for disaster management planners and policymakers,enabling the development of targeted strategies for sustainable urban river management and flood risk reduction in rapidly urbanizing river systems.The methodology presented applies to other urban areas that face similar flood risks.
文摘Metro is an important form of public transport in Shanghai.Based on the metro card data,we conduct the cluster analysis of Shanghai metro stations according to the pattern of passenger flow changing with time.Then the characteristics of travel time and surrounding land use are investigated for different types of stations to explore the relationship between urban land-use characteristics and travel activities reflected by passenger flow at metro stations.It is found that the passenger flow pattern of metro stations is closely related to the location conditions of stations and its surrounding land-use patterns.Based on various characteristics,285 metro stations are classified into four types,including residential-oriented stations,employmentoriented stations,employment-residence-oriented stations,and integrated functionaloriented stations,reflecting the interaction between spontaneous travel behavior and urban land-use characteristics and providing a reference for optimizing the urban functional structure and the spatial allocation of facilities.
基金Sponsored by Technology Research Program of Sichuan Province of China(2016JY0111)
文摘The metro is the most efficient and convenient public transport system in modern cities. For urban core areas in China, in which the metro was built later, there was more consideration for meeting the traffic needs of cities. However, there are few studies of collaborative planning for metro stations and their surrounding space. Thus, there is an urgent need to conduct research on collaborative planning for metro stations and their surrounding commercial space in urban core areas. Unlike conventional methods of integrated design of stations and cities, this paper, based on the theory of place spirit, took Chunxi Road Metro Station in Chengdu and its surrounding commercial space for example. It explored the pattern and characteristics of the place in the commercial space around the metro station, analyzed the strategies of cultural and commercial integration, as well as architecture, street, landscape and other aspects of the design method in the space, and explored the strategies of place-making and infiltration, providing a reference point for the development and place-making of the commercial space around metro stations in urban core areas.
