Subway Station Research Articles

Prediction of land use around urban metro stations using the CA-Markov model

ABSTRACT Analyzing how rail transit stations affect the land use changes around them in space and time is important for forecasting the future interaction between new stations and land use and for adjusting and optimizing planning schemes. Based on the design concept of station-city integration, this paper uses Zhongshanba Station of Guangzhou Metro as a case study. It examines the land use evolution around the station and predicts the future land use changes around the double-track transfer station of Line 5 and Line 11, using the POI kernel density and the passenger flow heat map of the existing station in the old city. The results show that the POI and passenger flow heat map are innovative driving variables that can increase the simulation accuracy of the CA-Markov model to 91.86%. The prediction results also show that public management-service land and residential land will increase while industrial land will decrease. Although garden land will expand, the surrounding ecological area is still inadequate. Finally, this paper provides some strategies for optimizing subway stations and planning urban land use.

Particulate matter and black carbon exposure in Seoul subway: Implications for human health risk

Air pollution and the associated health risks to humans caused by exposure to particle matter in enclosed subway systems are currently concerns. This research first time investigated the substantial health hazards (cancerous, non-cancerous, relative risk, and excess mortality rates associated with all-cause, cardiovascular, and respiratory mortality) posed by metals and black carbon (BC) bound to particulate matter (PM10, PM2.5) within subway systems. The Seoul subway system has been found to show notably higher levels of PM (2–1.5 times) and BC (2.3–1.3 times) compared to outdoor environments. Inhalation of PM-containing trace metals such as Cr, Ni, Cd, Pb, and BC significantly contributes to cancer risk, irrespective of age or PM type. The risk of developing inhalation-related cancer due to PM10 and PM2.5-bound metals is notably higher (1.2–2 times) within the subway environment compared to outdoors. Inhalation cancer risk levels (ICRBC) associated with PM-bound BC are 1.8 times greater at subway stations compared to outdoor stations, with a strong association (1.93–1.98 times) with PM2.5-bound BC compared to PM10. Notably, PM levels in subway stations have a considerable impact on relative mortality risk, with approximately 1.98 times the observed increase in mortality attributed to PM2.5-bound BC. The trace metals and BC bound to PM that contribute to human health risks might originate from vehicle emissions. This includes both surface and underground transportation systems. These findings underscore the significance of addressing air quality within subway systems to mitigate health risks.

Multiscale Impacts of Land Environmental Features and Planning on Apartment Resale Prices in Jinan City, China

As a typical city with a population of 5 to 10 million in China, Jinan has undergone significant increases in land supply during the past decade, resulting in substantial volatility in apartment sale/resale market prices. In this study, we investigated all second-hand apartment transactions from 826 communities of Jinan city and explored the multiscale impacts of land environmental features and planning on apartment resale prices throughout the city. Specifically, central and eastern regions had significantly positive impacts on apartment resale prices, while western regions had significantly negative impacts; education resources had consistently positive impacts throughout the city while shopping, business buildings, and medical resources had insignificant impacts; subway stations had insignificant impacts and bus stations had significant effects only in congestion points and northeastern edges. Our results revealed the formation mechanisms and spatial heterogeneity of apartment resale prices in Jinan. Our work will not only help in the decision making of potential apartment purchasers, but will also be conducive to enhancing the spatial justice of local governments in land supply and planning policies.

System reliability study of geothermal energy walls in subway stations based on rapid thermal performance prediction model

The energy conservation potential of relative systems in subway stations can be improved via the implementation of energy walls. However, current research mainly focuses on analyzing the factors affecting the energy walls' heat transfer performance, neglecting the reliability and performance assessment for ground source heat pump systems based on energy walls. This paper focuses on a subway station in hot-summer and cold-winter climate zone. Initially, both a resistance-capacity model and a 3D finite element model of energy walls are established. The resistance-capacity model is validated to be integrated with heat pump units to propose the rapid system performance prediction. Subsequently, the system thermal performance with the input of dynamic loads and conventional operational strategies is investigated. The results reveal that due to the heating and cooling load imbalance, the system inevitably experiences thermal imbalances and enters an inefficient operational state by the 6th year. Finally, to address this issue, a hybrid heat pump system with cooling towers is proposed, which demonstrates better thermal performance when used during non-cooling seasons. Another hybrid heat pump system for simultaneous cooling and heating is also proposed. These approaches both delay the onset of the system's inefficient operational state by 1–2 years, thereby improving the thermal performance.

Seismic performance of underground subway station structure near the strike-slip fault by the developed hybrid IBE-FEM method

To investigate the influence of strike-slip faults on the seismic responses of underground structures, based on the single-layer potential theory of the boundary element concept and the fault-site-underground structure coupling mechanisms, we proposed a hybrid indirect boundary element-finite element numerical method (IBE-FEM) to simulate efficiently the seismic response of the entire process from the near seismogenic-fault to the underground structure. Initially, based on the kinematic finite-fault model, the seismic wavefield of an overlying soft-soil sedimentary-layer site subjected to strike-slip faults with source parameters, such as rupture velocity, dip-angle, and upper-boundary burial depth, was solved using the indirect boundary element method (IBE). Subsequently, the accuracy of the IBE-FEM in predicting the site seismic wavefield was verified. On this basis, the influence laws of the source parameters and the fault-site coupling effects on the seismic performance of the structure were preliminarily investigated by establishing a numerical model of the nonlinear dynamic interaction system of a soil-underground structure. The results showed that the seismic responses of the underground structure located in the footwall far-fault region were more strongly affected by variations in the rupture velocity. The lateral deformation of the structure under the rupture velocity condition of bedrock shear-wave velocity (vs) was dramatically increased compared to sub-vs, and the lowest amplification is 59 %. Furthermore, the hanging wall and seismic damage concentration effects significantly impacted the structure located in a strike-slip fault site with a shallow-burial. This study provides a reliable and efficient analytical method for the seismic design of underground structures in complex near-fault regions.

Assessing Ground Motion Intensity Measures and Structural Damage Measures in Underground Structures: A Finite Element Analysis of the Daikai Subway Station

Research on the characterization of ground motion intensity and damage of underground structures is limited, while reasonable selection of ground motion intensity measures and structural damage measures is a crucial prerequisite for structural seismic performance evaluation. In this study, a two-dimensional finite element model of soil and structures was established based on the Daikai subway station in Japan. Through incremental dynamic analysis, 32 ground motion intensity measures and seven structural damage measures were comprehensively evaluated from seven properties, including efficiency, practicality, proficiency, scaling robustness, relativity, hazard computability, and sufficiency. According to the analysis results, the purpose and significance of each property during measure optimization were hierarchically sorted out. The results show that peak ground acceleration, acceleration spectrum intensity, and sustained maximum acceleration are recommended as ground motion intensity measures, while maximum inter-story drift ratio, column end displacement angle, and two-parameter measures are recommended as the structural damage measures for seismic performance evaluation of the shallow-buried subway station. Furthermore, measure optimization approaches are proposed as follows: the basic selection of IMs should satisfy scaling robustness, hazard computability, and sufficiency to site condition; the optimal selection of IMs is suggested to be evaluated mainly through efficiency, practicality and proficiency, and verified through relativity and relative sufficiency between IMs. The optimal selection of DM is suggested to be evaluated through four properties, including efficiency, practicality, proficiency, and relativity.

Intelligent Systems Integrating BIM and VR for Urban Subway Microenvironmental Health Risks Management

With the rapid development and construction of urban subways, various risks associated with human health and wellbeing within subway microenvironments have seriously increased. However, only a few intelligent systems have been validated as suitable for facilitating the management of subway environments. Field tests can be time-consuming and inefficient, and questionnaires often lack true intuitiveness for participants. Therefore, to enhance subway environment management, this study proposed intelligent systems that integrate building information modeling (BIM) and virtual reality (VR) for managing health risks in urban subway microenvironments. The systems were developed using Revit 2021, Navisworks 2020, Unity 2019, MYSQL 8.0, and Visual Studio 2019. Additionally, they were applied in scenarios for environmental assessment and passenger coping capability enhancement, differentiated into an expert visual-based health risk assessment system and a gamified simulation system for passenger risk prevention. The feasibility of the approach was validated with the case of Xinzhuang subway station of Line 3 in Nanjing, China. The findings revealed that the assessment system enabled experts to have a better and straight understanding of subway microenvironmental health risks and the gamification simulation system significantly enhanced the passengers’ coping capacity. The integration of BIM and VR, with its design features such as visibility, optimization, and simulation, compensated for BIM’s lack of providing an immersive experience for systems. The intelligent systems introduced in this study present novel models for environmental assessment and passenger training, catering to both subway operators and researchers. The innovative systems serve as a cornerstone in guaranteeing the health and safety of public transportation operations.

Levels, profiles and human exposure of organophosphate esters (OPEs) in dust from subway stations

For the first time, the pollution characteristics of eight organophosphate esters (OPEs) in dust from staff workspaces of subway stations were investigated in China. Dust samples were collected from ten stations, covering six rooms at each station, including offices, meeting rooms, dressing rooms, control rooms, equipment rooms and platforms within tunnels. The detection rates for seven compounds ranged from 68 % to 97 %, indicating widespread contamination. The median concentration of ∑OPEs was 23.31 μg/g, which was higher than that found in houses but not as high as that reported for station platforms and vehicle cabins. TnBP, TDCIPP and TEHP were identified as the predominant compounds, with concentrations ranging from 2.63 to 3.65 μg/g. The spatial distribution results revealed highly comparable concentrations in control rooms and offices but different profiles. Despite spatial separation between sampling sites, correlation analysis indicated strong links between tunnels and other sections of stations, suggesting the source consistency. Principal Component Analysis (PCA) results revealed that equipment shells, insulating rubber and cable jackets were major sources for control rooms and platforms within tunnels; oil-related sources influenced equipment rooms; and plastic decorations served as the main sources for station offices, dressing and meeting rooms. The hazard quotients (HQs, or noncarcinogenic risk) of ∑OPEs via ingestion and dermal contact for staff were all in the range of 10−4-10−2. Although the HQ levels were below the USEPA threshold, the occupational exposure risks through ingestion and dermal contact were greater than those in building environments and vehicle cabins.

Optimization of Evacuation Efficiency of Deeply Buried Subway Stations with Elevator Assistance

Optimization of Evacuation Efficiency of Deeply Buried Subway Stations with Elevator Assistance

Rainstorm-induced flood risk assessment in developed urban area using a data-driven approach with watershed units

Rainstorm flooding in developed urban areas has become a global focus. This study proposes a data-driven approach to urban rainstorm flood risk assessment. In contrast to the existing research, this study focuses on terrain watersheds as an assessment unit. Using Changsha as the study area, an inventory of 238 historical rainstorm flood locations was produced using automatic web crawling and literature data mining. Subsequently, an assessment model was developed based on a Bayesian algorithm and 16 influencing factors, and its accuracy was verified using a receiver operating characteristic curve. Because underground infrastructure is prone to backflow at its entrances and exits during rainstorms, the developed model was used to assess the backflow risk of two typical underground structures subjected to three rainstorm return periods: 5 (scenario 1), 10 (scenario 2), and 100 years (scenario 3). The conclusions are as follows: (1) The proposed method has a prediction accuracy of 88 % for flood risk. The most influential factors were H11 (proportion of impervious surface), H4 (mean elevation), and H1 (rainfall), contributing 52 %, 14.3 %, and 11.9 %, respectively. (2) Watersheds are classified into “Very Low,” “Low,” “High,” and “Very High” based on the degree of flooding impact, accounting for 83.6 %, 11.9 %, 3.9 %, and 0.7 %, respectively. Watersheds classified as “Very High” are mainly distributed in the central region. (3) A total of 48 subway stations (7.9 % of the total) and 148 underground parking lots (6.5 % of the total) in the study area are located in “Very High” risk areas. (4) Compared to that in scenario 1, the proportion of underground entrances and exits with a “Very high” protection level in scenario 3 increased by approximately 10 %. In conclusion, this framework can assist urban planners in understanding the risks of urban flooding and mitigating potential flooding impacts.

The influence of existing piles on station settlement during the construction of a tunnel undercrossing under existing stations

In the construction of tunnels under existing stations, it is necessary to control their settlement. When there is a pile foundation in the existing station, the pile cutting has a significant impact on the settlement of the existing station. To determine the influence of existing piles on the settlement of subway stations, a reasonable pile-cutting time is proposed. Based on the Chengdu Metro Line 9 underpassing the existing Line 1 hatchery station, the settlement law of the tunnel underpassing the existing Line 1 station is analysed via a numerical simulation. Furthermore, the deformation and stress characteristics of the existing piles, pipe roofs, and tunnel linings and the supporting effect on the existing station are discussed. It is concluded that the cutting of existing piles causes a change in the tunnel bearing system, thus resulting in a certain deformation of the station. The influence of different pile cutting times on the settlement of the existing station is then analysed, and it is clarified that the tunnel support stiffness is significantly enhanced after the construction of the secondary lining. At this time, the settlement of the existing pile station is significantly reduced. Finally, through a field investigation, the effect of surface grouting, pipe shed, and multilayer lining on the settlement control of the existing station while the existing pile foundation exists is determined. This research can provide a reference for the settlement control and foundation underpinning of existing stations at ultra-small distances in underground excavation tunnels.

Uncovering the spatiotemporal patterns of traffic-related CO2 emission and carbon neutrality based on car-hailing trajectory data

Traffic-related carbon dioxide (CO2) emissions constitute a significant portion of greenhouse gas emissions in urban areas, necessitating a comprehensive understanding of their spatiotemporal patterns and their implications for carbon neutrality. While previous studies have focused on exploring CO2 emission patterns, they often overlook the current carbon neutrality associated with these emissions. This study addresses this gap by investigating spatiotemporal patterns and carbon neutrality using car-hailing trajectory data from Xi'an, China. Initially, a link-based CO2 emission model is formulated by considering various driving conditions. Subsequently, the spatiotemporal patterns of traffic-related CO2 emissions are examined by kernel density estimation (KDE) and Getis-Ord models. Finally, carbon neutrality is assessed using the coupling coordination degree (CCD) model, which explores the relationship between traffic-related CO2 emissions and urban vegetation coverage. Empirical experiments found that hotspots of traffic-related CO2 emissions are concentrated at main roads or intersections, while coldspots are dispersed on residential roads. The findings highlight the significant influence of land use type, public services, and road levels on CO2 emission patterns, as well as the critical role of vegetation coverage in improving carbon neutrality levels. Based on these findings, several strategies are recommended to foster low-carbon city development, including expanding public transport services, integrating subway stations along main roads, optimizing traffic lights, increasing urban green spaces, and diversifying commercial facilities in traffic-related areas. These strategies emphasize the importance of incorporating carbon neutrality into urban planning and policy-making to achieve sustainable urban development.

Factors Influencing the Usage Frequency of Community Elderly Care Facilities and Their Functional Spaces: A Multilevel Based Study

The construction of community elderly care facilities (CECF) is pivotal for promoting healthy aging and “aging in place” for older people. This study focuses on the low utilization rates of community elderly care facilities in the Dongcheng and Xicheng Districts, core areas of Beijing. The explainable machine learning method is used to analyze data across three dimensions: the elderly’s individual attributes, characteristics of the community elderly care station (CECS), and features of the built environment around CECS and subdistrict, to identify the important factors that influence the usage frequency of overall CECS and its different functional spaces, and also the correlation between factors and usage frequency of CECS. It shows that the most important factors are the features of CSCF, including the degree of space acceptance and satisfaction with services provided, which influence the usage frequency of nine functional spaces (R2 ≥ 0.68) and overall (R2 = 0.56). In addition, older people’s individual factors, such as age and physical condition, significantly influence the usage of specific spaces such as rehabilitation therapy rooms and assistive bathing rooms. The influence of built environment characteristics is relatively low, with factors such as the density of bus stations and housing prices within the subdistrict and the mean distance from CECF to the nearest subway stations being more important. These findings provide a reference for the construction of indoor environments, management of service quality, and optimal site selection for future community elderly care facilities.

Understanding pedestrian crowd dynamics on ramps: An empirical study triggered by Seoul Halloween crowd crush

Pedestrian safety on ramps demands greater attention compared to flat surfaces, as exemplified by a tragic crowd crush accident that claimed the lives of over 150 individuals on a densely populated ramp in South Korea in 2022. Understanding the dynamics of pedestrian movement on ramps is crucial for effectively managing mass events and daily pedestrian transportation. This paper presents an empirical study investigating bidirectional pedestrian flows on a simulated ramp with varying inclinations. Flow ratios, indicating the group size of major and minor flows in both directions, were examined. Results show that bidirectional pedestrian streams exhibit self-organizing behavior, characterized by the emergence of distinct lane formation phenomenon in both level and ramp walking scenarios. The shortest overall time required for pedestrians to exit the ramp was observed at a 3° inclination. As the ramp inclination increases, the disparities between upward and downward directions become more pronounced. Specifically, the uphill flow consistently exhibits a lower average speed compared to the downhill flow at the same inclination. In general, an increase in inclination is associated with a decrease in forward speed, an increase in lateral speed, and a greater utilization of handrails. Handrail plays a particularly important role in assisting pedestrians down very steep ramps. Furthermore, we found that the influence of flow ratio on walking parameters undergoes a change from level walking to ramp walking scenarios. Notably, for the same flow ratio, the results can vary significantly depending on whether the major flow is uphill or downhill. Our findings provide valuable insights into crowd management on ramps and hold significant implications for the safer design of ramps in subway stations, underpasses, and overpasses.

Escalator Etiquette: Stand or Walk? A Systems Analysis

Users of escalators and moving walkways with sufficient space to accommodate two lanes of users often follow an implied etiquette for the two lanes: one for walking and one for standing (in the US, China, and many countries, the convention is “walk left, stand right”). When there is high volume, e.g., when exiting a subway or train station or at the conclusion of an athletic event, the escalators often experience bottleneck congestion that constitutes the primary source of delay. It has been suggested that during such high-congestion periods, it would be more efficient if everyone just stood in both lanes, with empirical evidence used to support this counterintuitive finding. Simple deterministic queueing models are used to show under what conditions such results hold and also to provide further insights regarding tradeoffs between performance metrics as a function of the distribution of walkers and standers, which could inform practical implementation policies to increase efficiency.

The Effect of Herding Behavior on the Efficiency of Pedestrian Evacuation in Subway Stations

In the emergency evacuation of pedestrians in subway stations, most people do not know the correct evacuation routes and methods, and tend to follow others blindly, resulting in herding behavior. To study the process of pedestrian evacuation with herding behavior in subway stations, a cellular automata pedestrian evacuation model is established to simulate the pedestrian evacuation with herding behavior in subway stations, and the effects of the weight coefficients of the parameters in the model on the overall evacuation time and the distribution of people’s positions are investigated to quantify the effects of herding on the efficiency of the pedestrian evacuation and the movement behavior. The simulation results show that moderate (kC < 40) crowd behavior can play a beneficial role in reducing reaction time and guiding the direction of evacuation; on the contrary, excessive crowd behavior (kC > 40) will lead to an increase in evacuation time and a decrease in evacuation efficiency. The conclusions presented in this paper can help to improve the efficiency of pedestrian evacuation in emergencies and provide a theoretical basis and practical guidance for the management of safety evacuation in subway stations.

Towards simulation optimization of subway station considering refined passenger behaviors

Towards simulation optimization of subway station considering refined passenger behaviors

Research on the Method of Determining Rainfall Thresholds for Waterlogging Risk in Subway Stations

With the frequency of extreme rainfall increasing, the risk of waterlogging is significantly exacerbated in subway systems. It is imperative to first identify the rainfall threshold for waterlogging risk for subway stations in order to develop effective waterlogging prevention and control plans. This study focuses on Line 11 of the Beijing Subway, using InfoWorks ICM to construct a model of the research area and simulate waterlogging at various subway stations under different rainfall scenarios. The results indicate that there is a risk of waterlogging at Jinanqiao station, Moshikou station, and Beixinan station on Line 11. The accumulated water may enter the subway station through exits A, B, C, and D of Jinanqiao Station. The inlet sequence of Jinanqiao Station always follows A(B), C, and D, and the difference in waterlogging time for each outlet does not exceed 10 min. We derived the rainfall threshold formula for waterlogging risk at Jinanqiao subway station. Among the three influencing factors of topographic features, step height, and drainage capacity of the pipeline network, step height has a significant effect on increasing the rainfall threshold for waterlogging risk. The conclusions obtained can provide reference for the refined management of waterlogging risks in subway stations.

Simulation of Near-Fault Pulse-Like Ground Motion and Investigation of Seismic Response Characteristics in Subway Stations

ABSTRACT The availability of reasonable input ground motions is a prerequisite for investigating the seismic response of near-fault structures. Currently, realistic near-fault pulse-like seismic records are lacking internationally. Moreover, the existing records exhibit distinct regional characteristics, which hardly meet the demand for seismic analysis of various engineering structures. Collecting and analyzing the pulse-like seismic records, a linear attenuation expression is proposed in this study to describe the time-varying frequency amplitude decay over duration. On this basis, a new model compatible with horizontal and vertical components is developed for near-fault ground motions. The model parameters are estimated for 100 near-fault records and regressed against the prediction equations. The variability and correlation of the ground motion in two directions are analyzed through the residual correlation matrix. Finally, taking a subway station as the engineering background, the effects of velocity pulse and vertical seismic motions on the underground structures are addressed through simulated motions and realistic records. Compared with existing approaches, the proposed method not only aligns with the time-frequency distribution characteristics of near-fault ground motions but also considers the correlation between horizontal and vertical components. In addition, consistent with the results from recorded ground motions, the synthetic motions yield enlarged seismic responses of the underground structure, thereby guaranteeing analysis accuracy for the engineered structures subjected to pulse-like ground motions. The inclusion of vertical excitation prominently amplifies the vertical displacement of the slab under pulse-like ground motions.

Non-linear impact of the built environment on metro commuter flows before and after the COVID-19 outbreak: A case study in Guangzhou

The built environment is a crucial factor influencing subway commuting. However, the extent to which the built environment affects metro travel during the COVID-19 pandemic remains under explored. In particular, people's travel patterns and destinations might have changed during the pandemic, influenced by the built environment. The degree to which these influences differ from those in normal circumstances has scarcely been studied. This study investigates the non-linear effects of the built environment on metro commuters within an 800-m radius of subway stations. Analysis of mobile signal data from Guangzhou Metro Line 1 showed that the importance of the built environment was 81.69% and 70.06% before and after the outbreak, respectively. Based on the threshold effects of the built environment on subway passenger flows before and after the pandemic, this study determined the immediate needs of commuters for the built environment after the outbreak. This information can guide planning strategies around subway stations facing public health emergencies. This study highlights the non-linear impact of the built environment on subway passenger flows after an outbreak. Thus, the number of parking lots, the proportion of medical facilities and the distance to the central business district are urgent demands for subway passengers after the outbreak.