Underground Transportation Systems Research Articles

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.

Evaluating accessibility to underground transport systems: analysis of the Santiago - Chile metro

Considering that a significant part of the world's population lives with some disability and life expectancy is increasing, accessible transportation would allow people to improve their quality of life and access more socioeconomic opportunities. Based on a mixed descriptive design (qualitative, ethnographic, and quantitative), this article presents a tool for evaluating the level of accessibility to subway trains for people with visual, physical, cognitive, and hearing disabilities. Data from 30 Metro stations in Santiago de Chile were analyzed, studying movements into the station, permanence in the payment area, and movements toward platforms and connecting lines. Among the indicators evaluated, those related to getting to the platform have the lowest levels of accessibility, as they do not meet all the needs of the different types of disabilities analyzed.

Evaluating accessibility to underground transport systems: analysis of the Santiago - Chile metro

This research aims to design and characterize plaster mortars based on perlite and lime produced in Ecuador, with a minimum compressive strength of 6.89 MPa, as established by IRC 2018, to be applied on rice straw panels. For this purpose, two standard mixes are designed. In the first, sand is used as fine aggregate, while in the second, perlite is used. Eight additional mixes are obtained from each one, where cement is replaced by lime (in volume) in different percentages. A total of 270 test specimens were made to evaluate the compressive strength and density of the mortars at 1, 3, 7, 28, and 50 days. The mortar made with perlite, comprising 50% lime, 50% cement, and an additive, reached a resistance of 7.22 MPa, with a density of 1.45 g/cm³. When this mixture was applied to the rice straw panels, it resulted in an increase of up to 68% in their compressive strength.

Predicting Tunnel-Induced Settlement in Cohesionless soils in Greenfield Condition

Rapid population growth and increasing congestion worldwide are placing greater demands on existing infrastructure. A solution to this problem is the use of tunnels to construct underground transportation systems. However, tunnelling induces settlement troughs that may result in severe or possibly irreparable damage to nearby infrastructure. For this reason, the effects of tunnelling must be well understood and predicted in the tunnel design stage, to prevent structural damage due to design oversights. Although tunnelling in clay has been extensively studied by previous researchers, the literature lacks reliable settlement estimation techniques for tunnels embedded in granular soil media. In this study, an extensive parametric analysis is conducted to examine the effects of the tunnel diameter, embedment depth, soil density, and shield conicity (tail void gap) on tunnel-induced settlement. Based on the results of the parametric analysis, the authors propose an effective, user-friendly solution that utilizes artificial intelligence software to predict tunnel-induced surface subsidence. The reliability and accuracy of the proposed solution are demonstrated by comparisons with 12 different sets of measured field data.

Simulation of carbon emission for mining‐separating‐backfilling integrated coal mines based on system dynamics

AbstractClarifying the influencing factors of energy consumption in underground production processes of coal mine is the premise and foundation for the coal mining industry to control the energy consumption and intensity to achieve the goal of carbon peak and carbon neutrality. This paper aims to investigate and compare the differences in energy consumption and carbon emissions between a mining‐separating‐backfilling integrated coal mine (MSBICM) and a traditional coal mine and explore the effects of the main production links underground on carbon emission intensity in coal mines. Hence, taking an MSBICM in Henan province as an example, this study constructed an energy consumption and carbon emission model of the mine using system dynamics (SD) method. Based on this model, the energy consumption of the main production logistics system and auxiliary production system in MSBICM was simulated and analyzed. In addition, this study made a comparative analysis of the energy consumption of the different production links in the two types of coal mines. The results showed that: (1) the comprehensive mechanized coal mining with solid filling system and ventilation system were the subsystems with the highest and lowest energy consumption in MSBICM respectively. (2) The influence rates of raw coal mining, gangue filling, coal‐gangue separating, and material transportation on carbon emission intensity in coal mine were 1.09%, 1.34%, 1.09%, and 5.13%, respectively. (3) Under the same production and filling targets, energy consumption of underground transportation systems in MSBICM was found to be 336.66 tons of standard coal less than that in traditional coal mine. This study has helped clarify the complex relationships among the factors that influence energy consumption in coal mines and provided a reference for implementing dual control of energy consumption to promote low‐carbon mining of coal resources.

A Critical Investigation on the Reliability, Availability, and Maintainability of EPB Machines: A Case Study

Tunnelling is a vital geotechnical engineering feature of underground transportation systems that is potentially hazardous if not properly investigated, studied, planned, and executed. A reliability, availability, and maintainability (RAM) analysis is one of the main practical techniques in machinery-based projects to recognize the failure and repair rates of machines during or after their operations. RAM analysis of mechanized tunneling can help to manage the project safety and cost, and improve the availability and performance of the machine. There are several methods to obtain and predict the RAM of a system, including the Markov chain simulation and other statistical methods; however, the result of the analysis can be affected by the selected method. This paper presents the results of a critical investigation on the RAM of the Earth pressure balance machines (EPBMs) used in developing an urban metro project in Isfahan, Iran. The five kilometer length of the first line of the Isfahan metro project was excavated using EPBMs over four years. After overhauling the EPBMs and making some minor changes, excavation of the second line started, and to date, about 1.2 km has been excavated by the refurbished machines. In the present study, a RAM analysis has been applied to electrical, mechanical, and cutter head subsystems of the EPBMs in Lines 1 and 2 of the Isfahan metro project over an 18- and 7-month period of machine operation, respectively. The results show that the estimated availability, A(t), determined by the Markov method, is closer to reality but cannot be propagated to reliability R(t) and maintainability M(t) analysis. It was also revealed that by predicting the required maintenance and proper planning, the overall availability of the EPBM was improved from 45% in Line 1 to 61% in Line 2. The outcomes of this study can be used in the future planning of urban tunneling projects to estimate machine, staff, and logistic performance with the least possible error, and appropriately arrange the factors involved in the system.

The influences of facilities management on mental health of underground development users during the pandemic in Hong Kong

The outbreak of COVID-19 has triggered an unprecedented health crisis across the world. Previous research indicated that the fear of being infected in public place has transportation hindered the commuters’ choice on. In fact, underground transportation systems, especially those located in high- density cities, have been perceived as high risk environments under the pandemic. In addition, the prolonged COVID-19 outbreak, together with the negative public impression towards underground environment, have to certain extent triggered various mental health responses amongst citizens (e.g., 42.3% increase of anxiety in Hong Kong). This study thus aims to investigate the impacts of FM on underground development users’ mental health in Hong Kong. To achieve this aim, a questionnaire survey approach is adopted. The survey is designed to contain three parts: background information, satisfaction towards underground FM (space management, building services, and supporting facilities related to the pandemic), and mental health level (emotional exhaustion, depersonalization, and claustrophobia). Data is collected over four underground subway stations in Hong Kong. Person correlation and regression analysis are conducted to determine the statistically significant relationships between underground FM and users’ mental health. The results indicated that satisfaction towards visual access, immediate access, and hygiene practices have negative relationship with the occurrence of emotional exhuastion and depersonalization, except for claustrophobia symptoms. The study results provide empirical evidence for practitioners to make informed decisions in FM plans for enhancing mental health of underground development users under and after the pandemic.

An overview of research on metro tunnel lining in the sub-rectangular shape

Circular tunnels are the most popular shapes used in urban underground transportation systems when mechanized tunneling is used for tunnel excavation. However, circular tunnels have a small space utilization ratio. With the material development, non - circular tunnels such as sub - rectangular, U - shaped lining, etc. are now common, and their cross - section helps to improve the underground space utilization. However, there have been not many studies on the structure and the calculation method of the metro tunnels with the above cross - sections. The paper uses the analytical synthesis method to find out the advantages and disadvantages, the application conditions of the sub - rectangular shape, as well as the development direction for the complete calculation methods for this cross - section in Vietnamese conditions.

Ground deformation mechanism due to deep excavation in sand: 3D numerical modelling

In densely built areas, development of underground transportation system often involves excavations for basement construction and cut-and-cover tunnels which are sometimes inevitable to be constructed adjacent to existing structure. Inadequate support systems have always been major concern as excessive ground movement induced during excavation could damage to neighbouring structure. A detailed parametric analysis of the ground deformation mechanism due to excavation with different depths in sand with different densities (Dr=30%, 50%, 70% and 90%) is presented. 3D finite element analyses were carried out using a hypoplastic model, which considers strain-dependent and path-dependent soil stiffness. The computed results have revealed that the maximum settlement decreased substantially when the excavation is carried out in the sand with higher relative density. This is because of reason that sand with higher relative density possesses higher stiffness. Moreover, the depth of the maximum settlement of the wall decreases as the sandbecome denser.The ground movement flow is towards excavation in retained side of the excavation. On the other hand the soil heave was induced below the formation level at excavation side. The maximum strain level of 2.4% was induced around the diaphragm wall.

Air quality issues in the Bucharest subway system

The subway transport method is come more popular in the last years and in some cities has become the primary public transportation mode. Many people are using the underground transport system because it is an efficient and fast. However, one environmental disadvantage of any underground transport system is that it operates in a confined space that may permit dust accumulation. The passenger typically spend only 30–40 min in metros, the air pollutants emitted from various interior components of metro system as well as air pollutants carried by ventilation supply air are significant sources of harmful air pollutants that could lead to unhealthy human exposure. This article presented the actual situation of the air quality from the subway transport system from Bucharest. An investigation was conducted among for underground subway stations to the examination of practical operation conditions of their cooling units. The overall field testing included information such as air conditioning system formation, equipment types and system.

Tunnel Shape Influence on the Tunnel Lining Behavior

Circular tunnels are the most popular shapes in urban underground transportation systems when mechanised tunnelling is used for the tunnel excavation. However, circular tunnels have a small space u...

System model building and dynamic online control of traffic flow

ABSTRACT The Underground transportation system plays a vital role in public transportation and exhibits complicated dynamics. The model predictive control approach for underground train dispatching is proposed in this paper. The system modelling technique spatially aggregates trains to generate the traffic flow model in a network of interconnected control units. The state-space model for the underground train traffic of a metro line is investigated. Simulation results are reported to demonstrate the effectiveness of the optimization control model.

Fault Diagnosis of Belt Conveyor Based on Support Vector Machine and Grey Wolf Optimization

Belt conveyor is widely used for material transportation over both short and long distances nowadays while the failure of a single component may cause fateful consequences. Accordingly, the use of machine learning in timely fault diagnosis is an efficient way to ensure the safe operation of belt conveyors. The support vector machine is a powerful supervised machine learning algorithm for classification in fault diagnosis. Before the classification, the principal component analysis is used for data reduction according to the varieties of features. To optimize the parameters of the support vector machine, this paper presents a grey wolf optimizer approach. The diagnostic model is applied to an underground mine belt conveyor transportation system fault diagnosis on the basis of monitoring data collected by sensors of mine internet of things. The results show that the recognition accuracy of the fault is up to 97.22% according to the mine site dataset. It is proved that the combined classification model has a better performance in fault intelligent diagnosis.

A review of flood impact assessment approaches for underground infrastructures in urban areas: a focus on transport systems

ABSTRACT Flooding events can produce significant disturbances in underground transport systems within urban areas and lead to economic and socioenvironmental well-known consequences, which can be worsened by variations in the occurrence of weather and climate extremes. A better comprehension of these impacts and their conditions is consequently needed. Hence, this paper presents a state-of-the-art literature review on flood impact assessment in “metro” systems, analysing their purposes and their shortcomings. This document shows the adaptation measures dealing with specific classes of pluvial flood damages, besides identifying prospective paths towards the application of suitable actions facing actual and projected hazards in metro systems worldwide.

Flood Risk Assessment in an Underground Railway System under the Impact of Climate Change—A Case Study of the Barcelona Metro

Flooding events can produce significant disturbances in underground transport systems within urban areas and lead to economic and technical consequences, which can be worsened by variations in the occurrence of climate extremes. Within the framework of the European project RESCCUE (RESilience to cope with Climate Change in Urban arEas—a multi-sectorial approach focusing on water), climate projections for the city of Barcelona manifest meaningful increases in maximum rainfall intensities for the 2100 horizon. A better comprehension of these impacts and their conditions is consequently needed. A hydrodynamic modelling process was carried out on Barcelona Metro Line 3, as it was identified as vulnerable to pluvial flooding events. The Metro line and all its components are simulated in the urban drainage models as a system of computational link and nodes reproducing the main physical characteristics like slopes and cross-sections when embedded in the current 1D/2D hydrodynamic model of Barcelona used in the project RESCCUE. This study presents a risk analysis focused on ensuring transport service continuity in flood events. The results reveal that two of the 26 stations on Metro Line 3 are exposed to a high risk of flooding in current rainfall conditions, and 11 of the 26 stations on Metro Line 3 are exposed to a high risk of flooding in future rainfall conditions for a 20-year return period event, which affects Metro service in terms of increased risk. This research gives insights for stakeholders and policymakers to enhance urban flood risk management, as a reasonable approach to tackle this issue for Metro systems worldwide. This study provides a baseline for assessing potential flood outcomes in Metro systems and can be used to evaluate adaptation measures’ effectiveness.

Hazards threatening underground transport systems

Metro systems perform a significant function for millions of ridership worldwide as urban passengers rely on a secure, reliable, and accessible underground transportation way for their regular conveyance. However, hazards can restrict normal metro service and plans to develop or improve metro systems set aside some way to cope with these hazards. This paper presents a summary of the potential hazards to underground transportation systems worldwide, identifying a knowledge gap on the understanding of water-related impacts on metro networks. This is due to the frequency and scope of geotechnical and air quality hazards, which exceed in extreme magnitude the extreme precipitation events that can influence underground transportation systems. Thus, we emphasize the importance of studying the water-related hazards in metro systems to fill the gaps in this topic.

Numerical modelling of effects of different multipropped excavation depths on adjacent single piles: comparison between floating and end-bearing pile responses

Owing to a shortage of land, high-rise buildings are increasingly preferred to meet the development and economic growth of major cities in the world. The construction of high-rise buildings often requires deep foundations such as single piles or pile groups when the underlying soil and rock strata do not have sufficient bearing capacity. On the other hand, underground basements are constructed to facilitate inhabitants in the buildings for parking. Development of underground transportation systems consist of tunnels, excavations for basement construction and cut and cover tunnels. These excavations are sometimes inevitable to be constructed adjacent to existing piled foundations. This research presents three-dimensional coupled consolidation analyses (using clay hypoplastic constitutive model that takes account of small-strain stiffness) to investigate the responses of a floating and an end-bearing pile due to adjacent excavation at different depths in clay. It was revealed that the maximum induced bending moment in both types of piles after completion of excavation in all the cases is much less than the pile bending moment capacity (i.e. 800 kNm). Moreover, the end-bearing piles were subjected to significant dragload due to negative skin friction. In contrast, no significant changes in load distribution along floating piles were computed.

Modern approaches to water drying in the underground transport system

The analysis of the process of electroosmotic water depletion in soils surrounding the track structure of the underground is given. It is established that due to the fact that the structure of soils is disturbed during the construction of the underground, the electroosmotic water loss in them has its own peculiarities, therefore it is necessary to optimize the process by the criterion of specific energy inputs for mass transfer.

The representation of evacuation movement in smoke-filled underground transportation systems

Limited guidance is available to engineers on how people’s walking speed in smoke can and should be represented in the fire safety design process of underground transportation systems, such as road and rail tunnels. To address this issue, the behaviour and movement of people in case of evacuation due to a fire in underground transportation systems has been investigated. In this paper, the relationship between walking speed and visibility conditions has been analysed by performing a systematic review of current experimental research conducted in the field. This includes data-sets collected in Sweden, Japan, UK, Norway, Finland, Canada, and The Netherlands. A design recommendation on how to represent walking speed in both smoke-free and smoke-filled environments is presented. Uncertainty in data is thoroughly discussed and addressed in the recommendation. Three different methods to represent walking speed during the design of an underground transportation system are suggested. The selection of the method depends on the required treatment of uncertainty in the design. The developed representation substantially differs from existing methods used in fire engineering design to represent walking speed in smoke since it describes walking speed as a function of visibility, rather than the extinction coefficient. This permits comparison of data-sets collected in relationship to the presence of reflecting or emitting lights. Finally, suggestions on future research to be conducted in order to reduce the current uncertainties are provided.

Underground transport: An overview

Transport systems play an essential role in urban, economic and social development. Utilising underground space for transport is a continuing trend across the globe during past decades. Underground transport systems have been chosen by cities as potential solutions for solving urbanisation problems such as traffic congestion, land shortage, and noise and air pollution. This paper provides an overview of five main forms of underground transport: underground railway systems, underground car parks, urban underground roads and expressways, underground freight transport systems and underground pedestrian systems. In each case the overview explores their origins, development, advantages and challenges, as well as other research foci. The paper then discusses key policy challenges for underground transport systems and provides recommendations for future research.