Underground Passages Research Articles

Architecture of transit spaces

The problem of modern cities is considered - the need to ensure efficient and comfortable movement of people and goods. With the development of transport, the issue of maintaining an attractive pedestrian environment arises. The concept of “architecture of transit spaces” and the role of transit routes in the planning structure of the city are revealed, and their diversity is examined. These spaces include various elements of urban infrastructure, pedestrian streets, boulevards, squares, underground passages, passages that provide connections between different parts of the city. The study identified four main groups of transit spaces: streets, bridges, covered walkways and temporary structures. Using the example of real objects, factors influencing the formation of transit routes, their scale and geometry, functional content and, as a result, the architecture itself are studied.

Effectiveness Verification of Evacuation Guidance Including Underground Passages Using Multi-objective Optimization

Effectiveness Verification of Evacuation Guidance Including Underground Passages Using Multi-objective Optimization

Elastic Local Buckling Analysis of a Sandwich Corrugated Steel Plate Pipe-Arch in Underground Space

In underground spaces, corrugated steel plate (CSP) pipe-arches may experience local buckling instability, which can subsequently lead to the failure of the entire structure. Recently, sandwich CSP pipe-arches have been used to enhance the stability of embedded engineering outcomes, and their buckling behaviors require in-depth research. In this paper, we establish a theoretical model by simplifying soil support and using Hoff sandwich plate theory to focus on the local buckling stability of the straight segment in embedded sandwich CSP pipe-arches using the Rayleigh–Ritz method. Through stability analysis, the instability criteria for embedded sandwich CSP pipe-arches are analytically determined. Numerical calculations reveal that the critical buckling load of a sandwich CSP pipe-arch is affected by several factors, including the elastic modulus, thickness, Poisson’s ratio, rotational constraint stiffness, and the length of the straight segment. Specifically, increasing the thickness of the sandwich CSP pipe-arch can substantially enhance the critical buckling load. Meanwhile, the wavenumber is affected by the elastic modulus and the length of the straight segment. The analytical results are in agreement with those obtained from finite element analysis. These findings provide a theoretical basis and guidance for the application of sandwich CSP pipe-arches in fields such as subway stations, tunnel construction, underground passages, and underground parking facilities.

Research on Mechanical Characteristics of TBM Cutter Bearing Based on DEM-MBD Coupled Simulation

Introduction: The cutter is a crucial excavation tool employed by Tunnel Boring Machines (TBM) for tunneling underground passages. During operation, it undergoes intense impact loads, which are transmitted to the bearings, thus posing a risk of bearing failure. Method: This paper combines the Discrete Element Method (DEM) and Multibody Dynamics (MBD) by establishing a coupled simulation patent model of the cutter and surrounding rock, various methods of cutter load profiles are compared. The study investigates the variation patterns of multi-directional rock-breaking loads on the cutter and validates the findings through wire-cutting experiments. Result: The research findings indicate that the discrepancies between the simulated and experimental mean values of the cutter's normal force and rolling force are 6.26% and 35.20%, respectively. The efficiency of cutter load transmission to the outer ring of the bearing is 99.10%, leading to the characterization of the vibration characteristics curve of the bearing's outer ring. Simultaneously, the mean square error of the cutter load obtained through the coupled method and traditional method is 78.50 kN and 76.10 kN, respectively. In comparison, the experimental load's mean square error is 99.20 kN, indicating that the coupled method better aligns with actual conditions. Conclusion: This research approach serves as a reference for TBM cutter performance analysis and bearing fatigue analysis.

Integrated geophysical approach for detection and size-geometry characterization of a multiscale karst system in carbonate units, semiarid Brazil

Abstract The karstification of carbonate rocks creates 3D maze voids that are normally controlled by fracture networks and sedimentary bedding. The spatial distribution and density of karst systems are usually complex and difficult to predict, demanding multidisciplinary studies at different scales of investigation to determine the spatial distribution and density of karst features and their possible links with cave systems controlled by the regional structural setting. The present study integrates geophysical datasets (gravity, electrical resistivity tomography - ERT, and ground penetrating radar - GPR) with a digital elevation model to investigate a karst system in the Irecê basin, a semiarid region of Brazil. Morphostructural lineaments reveal a NNW-SSE- and E-W-oriented structural setting of the crystalline basement, which is imprinted on the internal basin architecture, and surface drainage network. Negative gravity anomalies and high-gradient gravity zones indicate the main karstic zone, where karst landforms are concentrated. In addition, 2.5D gravity modeling provides the internal basin geometry, demonstrating that the karst system has evolved in the thickest sector of the basin. ERT profiles delineate the underground passages that connect dolines at depth. Finally, GPR data image shallow subsurface ghost-rock karstification that spread out from the surface to depth and that took advantage of vertical fractures and slightly arched bedding planes. Our results point out the role of the fracture corridors in channelizing hydrodynamic energy at a sufficiently high level to create caves by the total removal of dissolved material, whereas in the surrounding areas under low hydrodynamic conditions, overall shallow ghost-rock karstification took place, creating residual weathered rocks (alterites).

Complex Function Solution of Stratum Displacements and Stresses in Shallow Rectangular Pipe Jacking Excavation Considering the Convergence Boundary

The construction of pipe jacking has little impact on the environment and is usually used to build underground passages with shallow buried depths and short lengths. Compared with circular pipe jacking, rectangular pipe jacking has the advantages of shallow buried depth and high space utilization. Therefore, research on the excavation of rectangular pipe jacking is necessary. This paper establishes a cross-section model of shallow buried rectangular pipe jacking excavation. Taking advantage of complex functions for solving problems involving non-circular tunnels, an analytical solution is obtained using an approximate mapping function and potential functions in series forms for the stress and displacement of the stratum with a displacement condition at the excavation boundary and a stress condition at the ground surface boundary. The finite element simulation results and the engineering-measured data are used for comparisons and verifications. With the analytical solution of the complex function, the influence of selecting control points for the mapping function on the accuracy is calculated and analyzed, as well as the influence of the stratum loss rate, span, buried depth, and stratum unit weight on surface subsidence and major principal stress of the excavation boundary. The proposed analytical solution can be applied to the construction of rectangular pipe jacking tunnels.

Research on the positioning of underground passages constructed in private urban development in master plan and actual maintenance status

Research on the positioning of underground passages constructed in private urban development in master plan and actual maintenance status

MINIMISATION OF THE NEGATIVE EFFECTS OF EXPOSURE TO OF THE IMPACT OF INCENDIARY WEAPONS ON THE CIVILIAN POPULATION

Incendiary weapons are understood as incendiary substances and means of their combat use. Incendiary weapons are intended to defeat personnel, destroy and damage weapons and military equipment, structures and other objects. Throughout the history of warfare, incendiary weapons have caused suffering to millions of people who were not directly involved in the armed conflict. The situation remains unchanged today, with civilians being killed, injured or disabled for life, often losing loved ones or property as a result of the use of incendiary weapons. Virtually all existing publications on protecting people from incendiary weapons are focused on the protection of military personnel. There is very little information on how to protect civilians.
 An algorithm of actions for a civilian to minimise the negative effects of the impact of incendiary weapons has been developed. This algorithm includes the following actions: timely warn others about the use of incendiary weapons, help and, if necessary, guide the actions of those who need it (elderly people, children, people in panic); take shelter in the nearest civil defence structure, shelter (shelter). In the absence of such facilities, use underground passages, subway stations, basements and entrances of residential buildings, and shops; in the event of a sudden attack and the absence of nearby civil defence structures, shelters and refuges, use the protective properties of vehicles. It should be borne in mind that cars, buses and vehicles covered with tents provide only short-term protection, as they quickly catch fire.
 Use the protective properties of the terrain (uneven terrain, pits, covered public transport stops, fences, benches, curbs) to reduce the chance of pieces of incendiary material falling on a person; if it is impossible to find any shelter, lie down on the ground. Use local materials available to protect the surface of the body from incendiary weapons (suitcases, backpacks, billboards, paper clips). Burning surfaces are immediately thrown off and extinguished. Use personal respiratory protection equipment (handkerchiefs soaked in liquid, pieces of cloth) and skin protection equipment (cotton jackets, half-coats, raincoats, which are short-term protection equipment and should be immediately discarded if they come in contact with pieces of incendiary mixture); provide first aid to the victims. First aid shall begin with extinguishing by the victims themselves or with the help of surrounding inflammable substances that have got on their skin or clothing. At this point (period), no loss of self-control is allowed. To extinguish a small amount of inflammable substance, it is necessary to cover the burning area with a sleeve, jacket, wet clay, earth or snow. If several pieces of clothing are burning on your person, the flames should be knocked down by rolling them successively on the ground.
 If a significant amount of inflammable substance gets on a person, extinguishing is carried out by covering the victim with clothes, pouring water, covering with earth or sand.

Analysis of the application of modern means of detection and measurement of carbon monoxide when using alternative sources of electricity supply during the war in Ukraine

The article examines the impact of carbon monoxide on the human body, as well as the necessity of its detection and measurement. Carbon monoxide poisoning is very dangerous for human health and is accompanied by negative consequences and requires the implementation of new means of its timely detection and measurement. The article identifies the main sources of carbon monoxide, as well as assesses its impact on public health. The choice of modern means of detecting and measuring carbon monoxide is an important and necessary component of protecting people in modern realities. The work examines and analyzes the technical capabilities of modern cpaabilities of determining the level of carbon monoxide, defines the main models of carbon monoxide detectors, and also classifies and systematizes the peculiarities of their operation. The most convenient and practical portable carbon monoxide sensor. It does not require stationary installation. This is especially important in closed rooms, where carbon monoxide poisoning can occur instantly. The article analyzes literary sources in the field of the main types of alternative energy sources used in Ukraine during emergency and planned blackouts, as well as the dangers associated with them. The influence of dangerous and harmful factors affecting the human body during the use of these devices is considered: power banks, generators, batteries and inverters. The analysis of scientific research on ensuring safety when using alternative energy sources in domestic premises, private and multi-story buildings, factories, underground passages and storages was performed. The features of each type of modern signaling devices are analyzed. Recommendations are provided for the selection of modern means of detecting and measuring carbon monoxide.

Influence of extreme shallow jacked box tunnelling on underlying metro tunnels: A case study

The application of jacked box tunnelling for underground passages has grown rapidly in recent years in China. In this study, the design of an extreme shallow jacked box tunnel traversing the underlying metro tunnels was introduced. An innovative additional soil filling above the ground surface was carried out to overcome the overlying-soil-carrying effect of the extreme shallow jacked box tunnelling. The structural safety of metro tunnels during the jacking process was analyzed through in-situ monitoring. It indicated that the overlying-soil-carrying effect was successfully alleviated. The metro tunnels generally showed horizontal displacement towards the receiving shaft, uplift and horizontal stretch during the jacking process. The stop of jacking machine in front of obstacles generally contributed to the decrease of horizontal displacement, uplift and horizontal stretch of metro tunnels. The largest horizontal displacement (1.3–1.6 mm), uplift (1.5 mm) and horizontal convergence (1.6–1.8 mm) generally occurred when the reception of jacking machine was completed, and they all met the requirement of 2 mm for this project. The design and construction of this shallow jacked box tunnel project could provide references for future similar projects.

Застосування методів радіолокаційної інтерферометрії та георадарного знімання для моніторингу земель історико-культурного призначення

Goal. The purpose of the work is to consider the application of geophysical methods for local areas (satellite radar interferometry and ground-penetrating radar surveying) in determining the boundaries of lands of historical and cultural purpose. Method. A combination of methods for identifying or clarifying the boundaries of historical and cultural heritage objects for the establishment of protective zones is proposed. This combination includes two methods of determining or monitoring lands of historical and cultural purpose, namely satellite radar interferometry and ground-based GPR surveying. With the help of satellite radar interferometry, it is possible to determine vertical displacements of the earth’s surface, that is, subsidence of soils in places where there are possible elements of cultural heritage objects (underground passages or underground rooms on the territory of castle complexes, places of mass graves, etc.). After determining the locations of the largest vertical displacements of the soil, these areas are investigated by ground-penetrating radar for the detection of anomalies, which are subsequently deciphered. With the help of a combination of these methods, it is possible to identify additional elements of objects of historical and cultural heritage located underground without archaeological intervention. This allows clarifying the existing boundaries of lands of historical and cultural purpose or discovering new ones, which in turn affects the correction of protection zones. The results. As a result of the research, two examples of the discovery of new lands of historical and cultural purpose using a combination of satellite radar interferometry and georadar surveying in the village of Nitishyn and the village of Bryukhovychi are presented. These lands of historical and cultural purpose include mass graves from the time of the Second World War, the boundaries of which have been clarified using these methods, which serves as the basis for establishing protective zones. Practical value. The obtained results of the application of the methods of radar interferometry and ground-penetrating radar surveying in the study of objects of historical and cultural purpose can be used to clarify the boundaries of the land plots of the corresponding fund. It is more accurate to adjust the security zones according to the received border results.

Research into the cave complexes of the Kyiv-Pechersk lavra in the 1930s: overview of (little) known sources

The article deals with the sources concerning the history of the research into the cave complexes of the Kyiv-Pechersk monastery in the 1930 s – various materials created and/or made public at the time when the sacral complex system of interconnected underground passages and cave buildings was turned into the structure of the State Historical and Cultural Preserve «All-Ukrainian Museum Towns» and began to use it to demonstrate the inadmissibility of Christianity and to provide atheism propaganda. It is indicated that evidence of the «new research life» of the Lavra monastery underground complexes in the 1930s was partly archeographically published in the publications prepared by the National Preserve «Kyiv-Pechersk Lavra» research fellows. In the collection of unorganized, unrepresented in publications of recent decades and, for the most part, archival and museum sources on the history of the study of St Antony’s (Near) & St Theodosy’s (Far) Caves of the Kyiv-Pechersk Lavra during the 1930s, three groups are distinguished: articles and reports in the press and periodicals of that time; various archival documentary materials (papers, reports, correspondence); photographs that recorded the research process. For the first time, photos, reproduced from glass negatives, from the National Preserve «Kyiv-Pechersk Lavra» collection are introduced into scientific use. It is noted that the informational potential of the sources is not exhausted. The considered materials make it possible to verify the history of various directions, including archaeological, research into the Lavra underground labyrinths, clarification of the participants, analysis, evaluation of the results, etc. Key words: source study, St Antony’s (Near) Caves of the Kyiv-Pechersk Lavra, St Theodosy’s (Far) Caves of the Kyiv-Pechersk Lavra, archaeological research, Kyiv, 1930 s.

“They Shall Come into the Hollows of the Earth” (Isa 2:19): Bar Kokhba-Period Hiding Complexes at Biblical Tels—Tel Lavnin as a Case Study

Hiding complexes in Judea have been objects of considerable scholarly interest since the 1970s. By now, we are well acquainted with their main features and spatial distribution. Most hiding complexes in the Judean foothills were cut beneath the houses in Jewish villages. They were entered via shafts carved out of the nari rock, leading to underground passages quarried in the soft chalk beneath. Following recent intensive looting at Tel Lavnin, a site located in ‘Adullam Park, south of the Ela Valley, inspectors of the Antiquities Theft Prevention Unit of the Israel Antiquities Authority documented three hiding complexes. In this paper, we present these hiding complexes and the objects discovered in them. We discuss these complexes’ special architectural features and ponder why particular architectural methods were chosen. We then compare the complexes of Tel Lavnin to complexes documented elsewhere in Judea. We propose that they constitute an architectural subtype of hiding complexes from the Bar Kokhba Revolt and predict that others like them will be discovered in the future.

Time tweaks rodents’ subterranean hearing

Scampering through the tunnels of an underground rail station, we might feel like scurrying subterranean rodents, but our well-lit and ventilated tunnels bear little resemblance to the complex communal burrows constructed by rodent excavators. Apart from the lack of oxygen in remote burrow corners, sound carries differently through burrow tunnels than in open air. ‘Frequencies higher than 1 kHz are notably attenuated, even over distances of just a few meters, while lower frequencies are amplified’, says Kai Caspar from the University of Duisburg-Essen, Germany. In addition, the hearing of the rodent species that have descended beneath the surface has altered over time; the question was, had burrowing rodents lost hearing simply through lack of use, or had they actively adapted their hearing to their unique acoustic environment? For example, subterranean rodents could have reduced the sensitivity of their hearing to protect their ears from sounds amplified by tunnels, instead of allowing the sense simply to waste away.To find out, Caspar and his colleagues Alexandra Heinrich, Lea Mellinghaus, Patricia Gerhardt and Sabine Begall (also from the University of Duisburg-Essen) decided to test the hearing of three subterranean species: naked mole rats (Heterocephalus glaber) and Mashona mole rats (Fukomys darlingi), which took to burrowing ∼25 million years ago, and the South American coruro (Spalacopus cyanus), which only adopted a subterranean lifestyle 3.5 million years ago. The team gently anaesthetised the animals, ranging from youngsters to elderly seniors, playing sounds to the slumbering creatures ranging from a low-pitched 30 Hz buzz up to ultrasonic 36 kHz squeals at volumes of 10–80 dB, recording their brainwaves to determine their hearing thresholds at each pitch.And when the researchers compared the rodents’ hearing, it was clear that the hearing of the recent coruro burrowers was far more sensitive than the hearing of the long-term mole-rat excavators. The coruros could still hear ultrasonic sounds up to ∼32 kHz, while the Mashona mole-rats’ hearing tapered out around 4 kHz and the naked mole-rats could barely hear above 6 kHz. Both mole-rat species had lost hearing over the 25 million years since their subterranean shift. Yet, the hearing of all three species was most sensitive to sounds pitched around 1 kHz, which carry most strongly through underground passages. And, when the team recorded conversations between pairs of coruros, Mashona mole-rat duos and a trio of chirping naked mole-rats, the coruros spoke most softly (∼52.6 dB), while the naked mole-rats had the loudest voices ∼58.3 dB, probably to compensate for their poor hearing.So, it seems that rodents don't necessarily lose hearing sensitivity rapidly when they switch to burrowing for a living; coruros haven't done away with their ultrasonic hearing, even though high pitched squeaks barely carry beneath the ground. However, Caspar says, ‘life underground appears to quickly promote a shift of the region of best hearing to low frequencies around 1 kHz’. And, although some aspects of the rodents’ hearing could have dwindled through lack of use, the rodents seem to have tuned their hearing to be most sensitive to a specific range, ‘[possibly] to make the most of the unusual acoustic features of their subterranean homes’, says Caspar.Either way, mole-rat hearing is better than some had thought, in keeping with the creatures’ sociable lifestyle nattering in nest chambers, despite the toll taken over time by their subterranean existence on their appreciation of the squeakier end of the rodent range.

Specifics of road safety inspection in tunnels

Tunnels are underground passages, placed horizontally, which serve to lead the road through them. In order to fulfill its purpose in road traffic, the tunnel must fit into the traffic infrastructure and as such not create an obstacle in movement and enable the movement of vehicles from entrance to exit without danger, but with increased restriction of freedom of lateral evacuation. Tunnels are among some of the most risky parts of the road network, primarily due to space constraints, where there is a possibility of a traffic accident. Managing the risks associated with the passage of road traffic, and in particular the safety of traffic in tunnels, is a serious problem in many countries. With the growing number of road users, it is necessary to adopt stricter standards regarding road tunnels. In addition to meeting these safety standards, factors such as operational requirements, economic efficiency, energy efficiency and state-of-the-art technology should also be taken into account when planning and equipping tunnels.

Effect of Fungus-Growing Termite on Soil CO2 Emission at Termitaria Scale in Dry Evergreen Forest, Thailand

Termites are one of the major contributors to high spatial variability in soil respiration. Although epigeal termite mounds are considered as a point of high CO2 effluxes, the patterns of mound CO2 effluxes are different, especially the mound of fungus-growing termites in a tropical forest. This study quantified the effects of a fungus-growing termite (Macrotermes carbonarius) associated with soil CO2 emission by considering their nesting pattern in dry evergreen forest, Thailand. A total of six mounds of M. carbonarius were measured for CO2 efflux rates on their mounds and surrounding soils in dry and wet seasons. Also, measurement points were investigated for the active underground passages at the top 10% of among efflux rates. The mean rate of CO2 emission from termitaria of M. carbonarius was 7.66 µmol CO2/m2/s, consisting of 2.94 and 9.11 µmol CO2/m2/s from their above mound and underground passages (the rate reached up to 50.00 µmol CO2/m2/s), respectively. While the CO2 emission rate from the surrounding soil alone was 6.86 µmol CO2/m2/s. The results showed that the termitaria of M. carbonarius contributed 8.4% to soil respiration at the termitaria scale. The study suggests that fungus-growing termites cause a local and strong variation in soil respiration through underground passages radiating out from the mounds in dry evergreen forest.

Research on the Optimal Clearance Distance of Super-Large-Diameter Shield Tunnel Underpassing the Existing Metro Tunnel

With the accelerating urbanization in China and the constant development of underground space, shield tunnels have been extensively applied to underground roads in central urban areas. However, the central areas are featured with complex surroundings, such as numerous subways, bridge pile foundations, basements, pipelines, and other structures and buildings. Therefore, it will be an unavoidable engineering difficulty for the construction of shield tunnel in the central urban area to cross at a close range buildings (structures) such as existing tunnels, underground pipelines, underground passages and basements. At present, there are remarkable research results for the crossing of subway shield tunnel with an outside diameter of 6.0 m, and rich research results for the crossing of shield tunnel with an outside diameter of 10-14 m. However, there are relatively few studies on the shield tunnel with an outer diameter of 15 m and above crossing existing buildings (structures). Based on Shanghai Beiheng super-large-diameter shield tunnel (outside diameter 15.0 m), the Midas_GTS finite element analysis software was used herein to study the relation between the underpassing clearance distance h and the peak settlement of existing metro tunnel S. The optimal clearance distance of the super-large-diameter shield tunnel underpassing the existing metro tunnel in the soft soil area h was drawn to be 7.0∼8.0 m. Through analysis, it was found that the ground loss rate ρ and the tunnel peak settlement S of the existing tunnel was linear, with the slope = 2.795 > 1. It proved that the tunnel peak settlement S of the existing tunnel was significantly influenced by the ground loss rate ρ. Therefore, it’ s quite reasonable to take the ground loss rate ρ as the evaluation indicator and control requirement for crossing construction.

Analysis of floating effect of groundwater on built underground structure

With the continuous transformation of cities in China, urban land resources are becoming increasingly tense and traffic is becoming increasingly crowded. By building underground buildings such as subways, underground passages and underground shopping malls, we can not only make up for the shortage of existing space, but also rationally plan the urban layout. Therefore, it has become the first choice of urban construction in China. With the diversification of layout forms, the underground structure is increasingly developed in the depth direction, which highlights the anti-floating problem of underground structure. At present, the anti-floating design and construction of underground structures are not clearly defined by regulations in China, only the description of water buoyancy and requirements. In the actual underground structure engineering, the floating problem of underground structure is not uncommon. Therefore, how to design anti-floating measures is studied to ensure the reasonable application of anti-floating measures in the construction process.

Missing water from the Qiangtang Basin on the Tibetan Plateau

The Qiangtang Basin is a large endorheic basin in the inner part of the Tibetan Plateau, and has been thought to be a dry region in contrast with the surrounding wet outer region that feeds all the major Asian rivers. Combining surface hydrological data with modeling and satellite data from 2002 to 2016 CE, our study reveals that an enormous amount of water, ~54 ± 4 km3, is unaccounted for annually in the Qiangtang Basin. The amount of missing water is comparable to the total annual discharge of the Yellow River. Data from the Gravity Recovery and Climate Experiment (GRACE) satellite mission show little increase of local terrestrial water storage. Thus, the missing water must have flowed out of the basin through underground passages. Interpreting this result in the context of recent seismic and geological studies of Tibet, we suggest that a significant amount of meteoric water in the Qiangtang Basin leaks out by way of groundwater flow through deep normal faults and tensional fractures along the nearly north-south rift valleys that are oriented subnormal to and cross the surficial hydrological divide on the southern margin of the basin. Cross-basin groundwater outflow of such a magnitude defies the traditional view of a basin-scale water cycle and leads to a very different picture from the previous hydrological view of the Qiangtang Basin. This finding calls for major rethinking of the regional water balance.

Propagation Measurement of a Pedestrian Tunnel at 24 GHz for 5G Communications

In this paper, we report the results of a field measurement campaign carried out inside a pedestrian tunnel at 24 GHz in two conditions, namely, empty tunnel scenario and busy tunnel scenario with pedestrian movement. The experiment measures the fading effects of various groups of pedestrian crowds using directional antennas at the transmitter and receiver for millimeter-wave radio communications. Having presented and analyzed the measurement data in several diverse scenarios, we have further investigated human scattering effects in the crowded pedestrian tunnel and performed ray-tracing simulation for an empty pedestrian tunnel condition. Because tunnel is an enveloped scenario that is not bound by any geographic areas, the results of this study can be applied to a wider scenario like other pedestrian tunnels across the globe. Above all, these findings contribute towards ensuring wireless connectivity for everyone even in a remote scenario like underground passages.