Station Hall Research Articles

Concentration, composition and exposure risk assessment of particulate matter with different particle sizes in subway stations

Particle composition and risk assessment of their exposure in a subway station are very important for a station's environment and the health of people. However, only a handful of papers have compared and analyzed the composition of particulate matter and the risk of their exposure to people. To address these issues, environmental parameters and particulate matter were measured for one month at six different locations in twelve subway stations in a capital city located on the central coast of China. The particulate matter (PM), its composition and characteristics were analyzed and compared. The daily average exposure risk assessment model for the studied city was proposed to analyze the exposure risks associated with various particulate matters and metals for both commuters and workers. The results showed that, in all public areas (station hall, platform and carriage), the concentrations of PM were higher than those outside the subway station. The highest values of PM2.5, PM10, and TSP (total suspended particulates) were determined to be 158.3 μg/m3, 168.0 μg/m3, and 170.7 μg/m3, respectively. The physical characteristics showed that the surface of particles inside the station was rougher, larger and darker in color. Compared to outdoors, the particles within the subway stations contained much more metals, particularly Fe that had the mass fraction of 9.59 %. On the other hand, the outdoor environment did not contain any Fe. These findings indicated that there were original sources of contamination at subway stations, and the hazardous nature of the particles was particularly pronounced within subway stations. The exposure risk of TSP and metals for workers was nearly twice that of passengers. This study aims to provide data that could help in controlling the environment at subway stations.

Characteristics, sources, and improvement measures regarding fine particulate matter in subway station office and the VAC system.

In order to study the characteristics and transport path of PM2.5 in the subway station office, three different types of typical subway station were selected for sampling and analysis. The PM2.5 of mechanical air duct and VAC (ventilation and air conditioning system) were tested simultaneously. Both the particulate matter in the station office and VAC exhibit highly enriched characteristics of metal elements. The mass balance equation with elemental Fe as the tracer element is established firstly in subway station, and the transport path of PM2.5 in the work area is revealed: if the work area is obviously under positive pressure compared to the station hall, metal-enriched fine particles come from the VAC system; otherwise, the particles come both from the VAC system and air infiltration from the station hall. The contribution of air infiltration to metal-enriched fine particles can reach 50%. Finally, following an investigation into the source of fine particles in the office, the measures to improve air quality are proposed and validated.

Passenger flow bottleneck decongestion in subway stations: a simulation study

The impact of large passenger flow during peak hours causes serious congestion in subway stations, and passenger flow bottlenecks appear in many places, which affects travel efficiency and safety. How to eliminate the bottlenecks is an urgent problem to be solved. In this paper, we first analyze the causes and regions of bottlenecks, and we propose three decongestion solutions: (a) moving the security check machines from the station hall to the entrance channel; (b) adding isolation belts in front of the area of escalators; and (c) separating opposite passengers flow by using isolation belts. We conduct a case study on Guomao Station, Beijing, China to verify the effectiveness of the solutions. Specifically, we establish a microscopic model to simulate the passenger flow in a subway station, and the simulation results show that decongestion solutions can reduce the queueing length of security bottleneck by more than 30%, while decreasing the passenger density in non-paying areas of the station hall by more than 50%. The decongestion solutions proposed in this paper can eliminate the bottlenecks in subway stations effectively and practicably.

Dynamic evacuation path planning for subway station fire based on IACO

Fire in subway stations is the most serious type of accident causing casualties, and traditional static evacuation paths are no longer able to guarantee evacuation safety. To solve this problem, this study proposes an improved ant colony algorithm (IACO), which dynamically adjusts the evacuation paths by combining the simulation results of simulation software (PyroSim), and extends the available safe evacuation time of the personnel in a limited way. First, PyroSim is used to simulate the subway station hall and platform fire scenarios with the temperature, carbon monoxide (CO) concentration, and visibility at each location, obtained from twelve sets of monitors. Improvements in the pheromone concentration and update strategy of the ant colony algorithm (ACO) can improve the accuracy and convergence speed of the algorithm. Optimal path planning is achieved by the IACO, and then evacuation paths are dynamically adjusted by comparing the time at which each monitoring point on the path reaches the human hazard thresholds. Finally, until no adjustments can be made to obtain an evacuation path that extends the available safe evacuation time for personnel in a limited way. Compared to the traditional static evacuation path, this study provides a dynamic evacuation path that takes into account the real-time changes of fires in subway stations. This dynamic evacuation path planning approach will be put into use in subway stations before the accident to provide guidance on fire safety in subway stations and to provide contingency plans for emergency evacuation.

Health damage assessment of commuters and staff in the metro system based on field monitoring-A case study of Nanjing.

The metro has emerged as a major mode of transportation. A significant number of commuters and staff in the metro system are exposed to air pollutants because of its shielded environment, and substantial health damage requires quantitative assessment. Previous studies have focused on comparing the health impacts among different transportation modes, overlooking the specific population characteristics and pollutant distribution in metro systems. To make improvements, this study implements field monitoring of the metro's air environment utilizing specialized instruments and develops a health damage assessment model. The model quantifies health damage of two main groups (commuters and staff) in metro systems at three different areas (station halls, platforms, and metro cabins) due to particulate matter 10 and benzene series pollution. A case study of Nanjing Metro Line 3 was conducted to demonstrate the applicability of the model. Health damage at different metro stations was analyzed, and the health damage of commuters and staff was assessed and compared. This study contributes to enhancing research on health damage in the metro systems by providing a reference for mitigation measures and guiding health subsidy policies.

On group evacuation behavior of subway station halls using an improved evolutionary game model

This study is dedicated to examining the impact of stress on group evacuation behaviors in urban subway station fires, with the ultimate goal of improving evacuation efficiency and enhancing public safety. The authors have introduced an advanced evolutionary game model that combines “selfishness coefficient” and “stress threshold.” This introduces the concept of stress threshold and contributes to the exploration of stress propagation within groups. The simulation results indicate that the degree of selfishness in a crowd significantly affects evacuation efficiency. The emergence and propagation of stress emotions fundamentally represent a large-scale shift in individual evacuation behavior strategies within a group. At the onset of evacuation, the majority of the crowd follows an orderly and organized evacuation process, which occurs before the emergence of group stress. When the overall system benefit falls below the stress threshold, evacuees choose to crowd due to negative emotions and their pre-existing behavior strategies, leading the entire system into a “stress state”. Hence, effective strategies must simultaneously consider both physical methods and stress levels, lowering the threshold for orderly evacuation. For example, measures such as circular broadcasting and sending mobile messages can be employed to promptly inform evacuees about the on-site situation, and staff cab be deployed for guidance and comfort to improve people's sense of security. Analyzing evacuation patterns reveals factors influencing efficiency and individual behaviors, contributing insights to evacuation protocols and applications.

Evaluation of indoor particulate matter control based on health risks and oxidative potential in a metro station

Particulate matter (PM) from different sources exhibits diverse chemical and physical characteristics, and it is an essential carrier of toxic chemicals. Ignoring PM properties is inappropriate for indoor air quality (IAQ) control in places with internal sources, such as metro stations. PM control measures aimed at health protection should be established based on PM health effects. The current PM control limit for metro stations may be insufficient for health protection. It is important to find a method that comprehensively evaluates PM features to set PM exposure limits. This study evaluated the health risks induced by chemical components and the oxidative potential of PM in the Tianjinzhan metro station. A PM control strategy was suggested based on health effect analysis. PM on the platform had notable underlying adverse health effects. An in-depth toxicology analysis was suggested to assess the high Ba and Mn concentrations in PM. The risk from Cr raised concern regarding the potential for carcinogenicity. As a potential composite index, the dithiothreitol (DTT) activity may be appropriate to evaluate the general adverse health effects caused by PM. The DTT activity of the platform was 3.3–5.4 times that of the ventilation shaft. Removing a unit mass of PM1 in the station hall would produce more health benefits than the removal of a unit mass of PM2.5. However, the DTT results indicated that control strategies on the platform should first focus on PM2.5, which would achieve the same protection effect as that when the PM1 mass concentration is decreased by the same level. A revision of the PM2.5 control limit for China metro stations was recommended to control oxidative potential on the platform.

Study on the Impact of Health Condition Registration and Temperature Check on Inbound Passenger Flow and Optimisation Measures in a Metro Station during the COVID-19 Pandemic

The Guangzhou Metro Authority implemented health condition registration and temperature checks to curb the spread of the virus during the COVID-19 pandemic. However, it is important to investigate how these measures may have impacted the get-through efficiency and whether they caused the increased crowding at entrances and the station hall. To address these questions, simulation models based on the T Station were developed using AnyLogic. The model compared the get-through efficiencies with and without the anti-epidemic measures, while also analysing the risk of crowding at entrances and within the station hall after their implementation. Results revealed an increase in the number of passengers unsuccessfully passing through the check-in gate machines from 15% to 53% within 5 minutes, and 10% to 45% within 10 minutes when the anti-epidemic measures were in place. It was also observed that some entrances experienced significant crowding. Three measures were simulated to find effective ways to increase the get-through efficiency and mitigate the crowding – increasing the distance between security and health checks, utilising automatic infrared thermometers, and arranging volunteers or staff to assist with the registration process. The results demonstrated that using automatic infrared thermometers instead of handheld forehead thermometers proved to be effective in improving passenger efficiency and alleviating crowding at entrances and within the station hall.

Simulation analysis of evacuation processes in a subway station based on multi-disaster coupling scenarios

ObjectiveThis study aimed to improve knowledge on ways to effectively solve problems associated with subway station emergencies and provide methodological guidance for safety management. Process and methodA real case was considered—the Nanning Chaoyang Square subway station—and the AnyLogic simulation modeling software was used to build a simulation model of the evacuation process in the station in different disaster and disaster coupling scenarios. In particular, the characteristics of various disaster scenarios and the coupling effect between multiple disasters were analyzed, the social force model was improved during the analysis of pedestrian movement, and the key factors affecting the evacuation process in fire outbreak, flooding, and fire and flood coupling scenarios were analyzed. The number of evacuated pedestrians and evacuation times in each scenario were compared for analysis, to propose targeted suggestions. ResultsThe impact of fire products on pedestrians increased rapidly during the fire growth stage. When a fire or flood occurred on Side A of the station hall floor, the impact on the evacuation capacity was the greatest. The results support the claim that different multi-disaster coupling scenarios have different effects on evacuation risk owing to the influence of pedestrian evacuation strategies.

Prediction of Risk of Airborne Transmitted Diseases based on the Wells-Riley Equation: Applying in the Metro Hall Environments

The recent years have witnessed the increasing attention aroused by airborne transmitted diseases. Increasing evidence has shown that indoor air quality has a significant impact on people’s health, as well as the transmission of infectious diseases. As a result, more and more experts pay attention to the topic of airborne transmitted diseases. To improve the understanding of the risk of airborne transmitted diseases, in this paper we have reviewed the previous risk prediction model and tried to develop an improved model. The model, which has taken the size of space, the ventilation of the space, and the time of co-location, are also applied in a realistic model based on the system dynamic method, simulating the condition of passengers’ going into the station hall. According to the model and simulation outcoming, expanding the volume of room and ventilation can reduce the risk of infection. However, the co-location has a positive correlation with the infectious risk.

Optimization Path of Metro Commercial Passageway Based on Computational Analysis

In this study, three key factors affecting the planning of metro commercial passageways are selected: the built environment of metro station, travel purposes of passenger flow and gate position of the station hall. The Pearson model, Logistic model and software simulation are combined to analyze passage passenger flow. In the study of metro passageways, most studies focus on the optimization of evacuation and transfer functions, with little research on metro commercial passageways. The purpose of this study is to improve the attractiveness of metro commercial passageways to passenger flow by improving the three key factors mentioned above, thereby improving the current situation of underground commerce. The analysis results show that in the built environment analysis, the four selected construction factors are highly correlated with the passenger flow, and the correlation degree is in the following order (from high to low): length of the passage, operation of the escalators, the distance from the passage exit to the bus stop and the passage width. In the passenger flow travel purpose analysis, based on the structure of passengers and the function of the surrounding land use, it can be divided into shopping, work and living purposes, and the result of model parameter comparison shows that “shopping trips” is the most significant purpose. According to the analysis of the location of the exit gates at the station concourse level, the passageway with a closer distance or linear pattern to the gate location is more attractive to the passenger flow.

Research on Passenger Flow Control Plans for a Metro Station Based on Social Force Model

To better utilise the service capacity of the limited facilities of a metro station, as well as ensure safety and transport efficiency during peak hours, a large passenger flow control plan is studied through theoretical analysis and numerical simulation. Firstly, by passenger data collection and data analysis, the characteristics of the inbound and outbound passenger flow of a T metro station are analysed. Secondly, AnyLogic evacuation simulation models for the T Station during peak hours, peak hours without/with passenger flow control are established based on real passenger flow data as well as the station structures and layouts by using the AnyLogic software. The results show that there are no obvious congestions in the station hall, and the travel delay is significantly reduced when effective passenger flow control measures are taken. By controlling the speed, direction and movement path of passengers, as well as adjusting the operation of escalators, entrances and automatic ticket-checking machines, passenger flow can become more orderly, transport efficiency can also be improved, and congestion in the station can be well mitigated.

Intelligent Switch Based on Passenger Flow Detection of Urban Rail Transit

According to the demand of intelligent station construction in urban rail transit, the intelligent control of station hall, platform and other equipment places is improved, and the electrical equipment in the station is adjusted by intelligent passenger flow detection switch, so as to achieve the power consumption principle of " needed and supplied", which can ensure the use of equipment when the passenger flow in the station increases and realize energy saving and emission reduction when the passenger flow decreases. The application of intelligent switch device based on passenger flow detection in subway stations helps urban rail to grasp the passenger flow in time, reduces energy consumption, and effectively realizes energy saving and emission reduction while improving the efficiency and safety of intelligent management of station operation.

Evaluation of the Thermal Environment of Xi’an Subway Stations in Summer and Determination of the Indoor Air Design Temperature for Air-Conditioning

Taking two typical subway stations in Xi’an as the research objects, the thermal environment and human thermal comfort of the station in summer were studied based on field measurements and a questionnaire survey. Based on the relative warmth index (RWI), the passengers’ thermal comfort during the process from entering to leaving the station under the operating temperature and the designed temperature was also analyzed. Moreover, the RWI method was modified based on the comparative analysis of the predicted results from the RWI and questionnaire methods. Then based on the revised RWI method, the suitable indoor air design temperature in Xi’an subway stations was discussed. The research results revealed that if the air-conditioning system was operated at the design temperature suggested by Code GB 50157-2013, it cannot meet the thermal comfort needs of most passengers. Only when the temperature of the platform was at least 1 °C lower than that in the station hall did the passengers obtain temporary relative thermal comfort. According to the control proportion that 25% of passengers need a cooler environment, the indoor air design temperature for air-conditioning in Xi’an subway stations should be 25.5 °C in the station hall and 24.5 °C on the platform.

Numerical and Experimental Investigation on the Effect of Mechanical Smoke Extraction Caused by External Wind in Subway Station Halls

When fires break out in subway station halls, traditional smoke extraction (TSE) systems are employed with the aim of preventing smoke from spreading to the platform and passageways. The functionality of TSE systems under the influence of external winds needs to be further explored. Based on a numerical method, this study investigated the effect on TSE systems under the influence of external wind. A numerical model was established and validated by means of full-scale field tests to ensure accuracy. Subsequently, the validated model was applied to study the effect of the external wind directions and speeds on the smoke diffusion distance. The results showed that when all entrances and exits were on the windward side, the external wind direction led to serious longitudinal diffusion of the smoke toward the side with fewer entrances and exits of the station hall, and the diffusion distance increased with increasing wind speed. The diffusion distance reached a maximum value of 61.32 m when the outdoor wind was 5 m/s, which was 67.9% higher than that under no wind. When all the entrances and exits were on the leeward side, the external wind had little influence on the degree of smoke spread, with the greatest smoke diffusion distance being only 4.76% longer than that under no wind. When two entrances and exits were on the windward side and the other on the leeward side, the external wind caused smoke to spread to a passageway, and the degree of smoke spread was more unfavorable at higher wind speeds, with the longest diffusion distance being 7.28 m. To prevent smoke from spreading to passageways and to effectively shorten the longitudinal diffusion distance of smoke, an optimized smoke control (OSC) system was proposed, employing center and passageway smoke barriers, which were able to shorten the diffusion distances by 35.45%, 13.64%, and 2.35%. In particular, smoke diffusion did not occur in passageways. This study provides a reference for the fire safety engineering design of subway stations.

Analysis and Research on the Thermal Environment of Subway Stations in Wuhan

With the rapid advancement of urban construction, urban subway construction in China has entered an advanced development stage and the thermal environment of subway stations has become a key factor affecting passengers' thermal comfort. To further understand the actual situation of the thermal environment of subway stations, field measurement and CFD simulation were carried out on a subway station hall in Wuhan from July to August 2021, and the thermal environment changes and influencing factors during subway operation were compared and analyzed. The present situation of the thermal environment in subway stations was analyzed, and some suggestions and measures for improving the thermal environment were put forward.

Hybrid Scheduling Model Based on Fare Incentives for Peak Time Interval of the Metro: The Harbin Metro System

Considering the operation efficiency of the metro system, the boarding queuing problem is a complex and intractable dilemma caused by the security and ticket checking process in urban metro stations, especially for the mass-transit metro system in China. In this study, a novel scheme of fare differentials based on demand control and congestion management for reducing congestion in the metro boarding process was proposed. In addition, we extended Vickrey’s point-queue model into a boarding congestion model incorporating the bidesired departure time considering the security and ticket checking process in stations as a continuum bottleneck. The train-run and departure time choosing behaviors of passengers under different schedule gaps of the adjacent train runs are explored when the boarding system achieves user equilibrium in the proposed model. Then, we examined the demand regulatory mechanisms of fare incentives (fare differentials) in reducing the queuing boarding time in metro stations when the optimization of the schedule gaps is ineffective in the pattern of mass-scale travel demand. The analytical solutions of these two optimal methods (schedule gaps and fare differentials) for boarding congestion management are presented. After comparing the two congestion-reduced methods, the fare incentive rule has a better regulation effect on the smoothing of travel demand. The results of the sensitivity analysis using numerical simulations reveal the regulatory mechanism of fare differentials in reducing the queuing time and increasing the incremental revenue. (1) The demand threshold is only related to the boarding capacity and schedule gaps (i.e., the greater the boarding capacity and schedule gaps, the greater the passenger capacity of the metro station). (2) The effect of fare incentives in reducing the boarding congestion is better if the lower fare is implemented in the later train runs. (3) A lower fare differential between two adjacent metro runs can be used to regulate the proportion of staggered passengers in the queuing line to reduce the crowd gathering in the metro station hall when travel demand is high, meanwhile, a higher fare differential between two adjacent metro shuttles can increase incremental revenue effectively. (4) The measure of fare differentials causes worse results in both the reduction of the queuing time and the increase of the incremental revenue when the metro travel demand is lower than the demand threshold. This conclusion is consistent with the pattern of reality and experience. Therefore, the definition and judgment conditions of demand thresholds, introduced in this study, can provide theoretical guidance when implementing fare incentive policies in aviation and metro networks.

Characteristics of subway air quality and favorable locations for passengers waiting and taking the subway

With the increase of commuters in Beijing subway, the air quality inside subway systems has caused widespread apprehension. The particulate matter (PM) level and potential health risk of PM on the platforms and carriages of Open (O) system, Half-height platform door (HPD) system, Full-height platform door (FPD) system, Platform screen door (PSD) system were studied. The average PM2.5 concentration was approximately twice the Chinese National Ambient Air Quality Standard Class II threshold and ten times the WHO Global Air Quality Guidelines. The average PM2.5 and PM10 ratios on the platform and inside carriages were 0.81 and 0.85, respectively. Compared to the FPD and HPD, the PSD has the highest ability to prevent tunnel dust entering the platform, whereas, the FPD's preventive ability is insignificant. The maximum comprehensive indoor-air quality index (CIAI) values for platform PM2.5 and PM10 are at a very unhealthy risk level and unhealthy risk level, respectively. The average PM2.5 doses deposited by adult males in extrathoracic (ET), tracheobronchial (TB) and alveolar-interstitial (AI) during a day's round-trip ride were 163.7 μg, 9.6 μg and 24.1 μg, respectively. The PM concentration at the station platform nearer to the entrance location is greater than the middle of the platform and the center of the station hall. The PM concentration at the middle of the carriage between two doors is lower than that at the door. The research results have important guidance for constructing a subway environmental control system, station passenger flow command desk setting, passenger waiting and taking the subway to reduce the health risk.

Characteristics of Dynamic Safety Factors during the Construction Process for a Tunnel-Group Metro Station

Dynamic safety factors during the construction of an overlapping tunnel-group metro station were studied in the framework of the strength-reduction finite element method. Based on the equivalent plastic strain and displacement of surrounding rock, its damage mode under typical excavation conditions was investigated. The aim of this investigation was to provide information for the design activities concerning the supporting system of the station and the pre-reinforcement of its surrounding ground. The accuracy of the model was assessed by comparing the ground settlements obtained from on-site monitoring with those from the numerical model. The analysis results show that the safety factor reaches the minimum when the No. 3 guide hole of the station hall is excavated. Thus, this is the most dangerous construction step. During this step, the plastic zone penetration phenomenon occurs in the surrounding rock, which is sandwiched between the hall and the platform of the station. In this case, both the deformation of the surrounding rock and the internal forces of the lining increase. The surrounding rock in the sidewall loses its stability. Thereafter, the primary support plays a role of stabilizing the guide hole.

Study on an emergency evacuation model considering information transfer and rerouting: Taking a simplified H-shape metro station hall as an example

Metro has already become one of the main transportation methods in big cities across the world. With the development of metro systems, lots of associated safety issues (e.g., fire accidents and terrorism attacks) have occurred in the past decades. Under such circumstances, studies on the safety evacuation of the metro station hall are very necessary. Due to high human-density, fluent evacuation is important in the metro station hall in emergencies. However, metro station hall evacuation is a complex process, filling with humans of different behavior biases. Selection of evacuation direction usually is influenced by accessing information and human decision-making inevitably. Therefore, the paper proposed an evacuation model based on information transfer and rerouting, mainly concentrating on panic propagation, human decision process and human interaction, in order to examine the effects of these factors on evacuation. Results show that emergency information transmission is crucial in accelerating evacuation since stronger information intensity brought from panic propagation improves the evacuation efficiency. The guidance of human flow during evacuation can unify evacuation behavior and the diversion of the crowd at the exits can make full use of the evacuation capacity of exits. Before the timestamp of 39, which corresponds to the time at which the people reach the exit, the human crowd walking in the corridor generally evacuate faster in the unified direction under the control of the herd mentality model. After that, masses gathered at the exit, and the social force model displays a better evacuation effect because of crowd diversion. Spontaneous rerouting may aggravate the evacuation chaos, while scientific evacuation route guidance and command is more reasonable and reliable. These conclusions will guide the process in making evacuation plans for the metro station hall and provide a new perspective to examine evacuation by considering human factors that are closer to the real situation.