Underground Metro Station Research Articles

The Use of Underground Metro Stations and Tunnels as Protective Structures in Case of Nuclear Emergencies

The Use of Underground Metro Stations and Tunnels as Protective Structures in Case of Nuclear Emergencies

Chemical Characterization of Airborne Particles Collected in an Underground Metro Station Platform in Delhi City

Chemical Characterization of Airborne Particles Collected in an Underground Metro Station Platform in Delhi City

On-road PM2.5 pollution exposure in multiple transport microenvironments in Delhi

Abstract PM2.5 pollution in Delhi averaged 150 μg/m3 from 2012 through 2014, which is 15 times higher than the World Health Organization's annual-average guideline. For this setting, we present on-road exposure of PM2.5 concentrations for 11 transport microenvironments along a fixed 8.3-km arterial route, during morning rush hour. The data collection was carried out using a portable TSI DustTrak DRX 8433 aerosol monitor, between January and May (2014). The monthly-average measured ambient concentrations varied from 130 μg/m3 to 250 μg/m3. The on-road PM2.5 concentrations exceeded the ambient measurements by an average of 40% for walking, 10% for cycle, 30% for motorised two wheeler (2W), 30% for open-windowed (OW) car, 30% for auto rickshaw, 20% for air-conditioned as well as for OW bus, 20% for bus stop, and 30% for underground metro station. On the other hand, concentrations were lower by 50% inside air-conditioned (AC) car and 20% inside the metro rail carriage. We find that the percent exceedance for open modes (cycle, auto rickshaw, 2W, OW car, and OW bus) reduces non-linearly with increasing ambient concentration. The reduction is steeper at concentrations lower than 150 μg/m3 than at higher concentrations. After accounting for air inhalation rate and speed of travel, PM2.5 mass uptake per kilometer during cycling is 9 times of AC car, the mode with the lowest exposure. At current level of concentrations, an hour of cycling in Delhi during morning rush-hour period results in PM2.5 dose which is 40% higher than an entire-day dose in cities like Tokyo, London, and New York, where ambient concentrations range from 10 to 20 μg/m3.

Smoke Spread in Underground Metro Station

In the event of subway train fire smoke is the most fatal factor because smoke spreads in direction coincide with passenger’s evacuation path. It reduces visibility and can cause fatalities by asphyxiation. This research presents a numerical study to investigate the effect of exhausting smoke by single point extraction and exhausting smoke by multi- point extraction on passengers’ life safety. Also, effect of adding smoke barriers at stairs entrance on passengers’ life safety is studied. Fire Dynamics Simulator (FDS) software version 5.5.3 is utilized to simulate 6 case studies in 150 m long, 20 m wide and 13 m height domain with a subway car fire source simulated as a fire with unsteady heat release rate of 35 MW resulted from burning Heptane as a fuel. Results show that exhausting smoke by multipoint extraction system in underground subway station gives better performance than single point extraction system. By increasing the distance between vents in multipoint extraction system, tenable conditions improves at human level. Smoke barrier addition to ventilation system has a great effect on the efficiency of smoke extraction and improving tenable conditions at human level.

Stratified Settlement Characteristics of the Soil Strata in Shanghai due to Dewatering

AbstractDewatering-induced ground settlement is an important issue, and there a cumulative effect in stratified soil settlement. Detailed research of the stratified soil settlement devotes to a better evaluation of ground settlement. To better investigate the dewatering-induced stratified settlement characteristics of the soil strata in Shanghai, an intensive field-monitoring program was carried out for the excavation of an underground metro station, which involved the dewatering of confined aquifers in urban areas. Analyses of monitoring results suggest that the groundwater tables dropped steadily. The ground settlement decreased with an increasing distance from the excavation, and the maximum ground settlement was less than the allowable value. The results for stratified settlement monitoring showed that the ground settlement was less than the settlement at the bottom of the soft soil clay layer, which indicates that the clay layer swelled during dewatering in the underlying soil layer. This special phe...

A breakdown of energy consumption in an underground station

Abstract Underground transportation systems are big energy consumers and have significant impacts on energy consumption at a regional scale. The literature has revealed that the energy consumption for non-traction purposes may be of the same magnitude as the energy used to move rolling stock, and in some cases even greater. However, most of the research conducted so far has focused on the energy demand of rolling stock. This paper investigates the electricity consumption of an underground metro station using data from on-site surveys and measurements. With an average consumption of 217.64 kWh/m2/year, the breakdown revealed that the lighting system dominated the underground station's energy consumption (37%). Illuminated advertising signs were found to be responsible for 14% of the total energy consumption, and ventilation accounted for another 14%. The rest of the energy consumption was attributed to systems such as mobile phone signal antenna (12%), the vertical transportation system (8%) and small power devices (5%). Accurate information on energy consumption for non-traction usage is useful for future implementation of energy conservation measures in underground stations, which could result in a reduction of operating costs in the long run.

Full-scale experiment and CFD simulation on smoke movement and smoke control in a metro tunnel with one opening portal

Three full-scale model experiments were conducted in a unidirectional tube, which is a part of a metro tunnel with one end connected to an underground metro station and the other end opened to outside in Chongqing, PR China. Three fire HRRs, 1.35MW, 3MW and 3.8MW were produced by pool fires with different oil pan sizes in the experiments. Temperature distributions under the tunnel ceiling along the longitudinal direction were measured. At the same time, CFD simulations were conducted under the same boundary conditions with the experiments by FDS 5.5. In addition, more FDS simulation cases were conducted after the FDS simulation results agreed with the experimental results. The simulation results show that the smoke temperature and the decay rate of the temperature distribution under the tunnel ceiling along the longitudinal direction increase as HRR increases. The smoke exhausts effectively from the tunnel under mechanical ventilation system, whether the emergency vent is activated as a smoke exhaust or an air supply vent. The operation mode of the mechanical ventilation system depends on the evacuation route.

Numerical modeling of ground settlement control of large span underground metro station in Tehran Metro using Central Beam Column (CBC) structure

The ground surface settlement caused by underground excavation is an important matter in urban development. The settlement control of large span underground station in Tehran Metro is investigated using a full three-dimensional (3-D) finite element analysis. A method of underground construction by increasing the rigidity of the supporting system using Central Beam Column (CBC) structure is introduced. In construction of large underground space, effect of presence of CBC structure is compared to a case without CBC structure. The CBC structure increases the rigidity of supports and decrease the stress concentration and displacement in supporting system. It generally decreases the soil deformation above the underground space resulting in smaller ground surface settlement.Influence of spacing of central columns and their dimensions on the magnitude of settlement are also investigated in this study. Effect of ground improvement of Tehran soil by consolidation grouting on ground surface settlement and stress distribution in supporting system is modeled and analyzed. It can be concluded that in an urban area over a large underground spaces (e.g., underground metro stations) with relatively low overburden similar to northern Tehran, CBC structure can be very effective and reliable measure in controlling and reducing the surface settlement and the stress concentration on initial supporting system.

Alteration Features of Stones Applied in Underground Metro Stations

Several types of stones (igneous, sedimentary and metamorphic) are found applied in pavements, stairs and walls of the underground stations of the Lisbon Metropolitan System, Portugal. A field study based solely on non-destructive and non invasive visual inspection of these stations is presented, aiming to identify different transformations of applied stones and discuss its relation with the stone characteristics. This field study has pointed to relevant issues regarding durability of stone materials namely when used in pavements and stairs. The most striking aspect is the frequently marked variable behaviour of stones from a given rock type under the same use conditions, with heterogeneities and discontinuities that seem to cause irregularity from the early stages and further increase with time, having more accentuated consequences (in terms of intensity of surface irregularity) in some types of limestones. The observations collected could be relevant for the discussion of characteristics relevant for the quality control of these materials (namely at the quarry level), including the selection of stones for future substitutions. There is, therefore, the need for a more complete study comprising detailed petrographic studies and laboratory tests both from the applied stones and from the supplying quarries.

Three-dimensional numerical analysis of stress and deformation of surrounding soil in safety construction of metro station

Utilizing underground spaces synthetically has become an important task in urban planning and civil engineering in this century. Due to the complexity and uncertainty of technical issues in underground construction and soil engineering, construction safety arouses a great concern in underground construction industry. This paper focused on construction of an underground metro station, numerical analyses are carried out to estimate the possible stresses and deformations of surrounding soil and underground structures under the worse loading conditions to assess the structural design and construction safety. Influences of pit excavation on existing tunnel and surrounding spaces are discussed and the stability of main structure of metro station will be analyzed.

Modelling periodic scene elements for visual surveillance

Some urban scenes exhibit periodic variations that can be relevant to visual surveillance applications. One example is the variation in the background elements, such as those caused by moving escalators, lights and scrolling advertisements. When modelled correctly, the incorporation of these periodic elements as a Markov model in a foreground detection component can improve the performance significantly. Another area where the periodicity in the scene can be used is anomaly detection. In some underground metro stations where the flow of people is periodic, deviations from this periodicity can be interpreted as abnormal movements of people. This can be achieved by using a higher-dimensional model for the underlying data structure, and mapping it to a one-dimensional signal for interpretation. This approach is tested, and the results show that abnormal behaviour can be automatically detected.

Acoustical Design and Noise Control in Metro Stations: Case Studies of the Ankara Metro System

The aim of this research is to demonstrate the importance of initial strategies in acoustical design of underground metro stations. The paper searches for practical design solutions by evaluating different materials for providing optimum acoustical conditions in such spaces. Acoustical designs of three metro stations on a new expansion line in Ankara including Sogutozu, Bilkent and ODTU metro stations are presented through computer simulation. Predictions of room acoustical parameters are presented for both platform and ticket office floors in terms of parameters like reverberation time (RT), speech transmission index (STI) and A-weighted sound level (SPL) distribution within spaces. Simulated reverberation times are evaluated in view of legislative requirements. The study confirms the importance of using sound absorbing materials on the ceiling and sidewalls together. The nonwoven material, used behind perforated metal suspended ceilings, has proved effective in reverberation control.

Analyzying Environmental Noise Within Semi-Closed Spaces (A Case Study, Al-Souk Al-Saglicer Tunnel in Mecca).(Dept.A)

Pedestrians within enclosed or semi-enclosed spaces suffer from being subject to high levels of environmental noise. Such levels could affect their health, both sociologically and physically. Places such, underground metro stations, multi story garages and dual disc tunnels are places where pedestrian activities mixes with traffic and machinery noise. Al-souk Al-Sagheer tunnel, within the central area of Mecca city, presents one of theses spaces. The research presents an analytical approach to evaluate the hazard risk within such spaces. Comparing pedestrian activities with noise levels in the main and sub areas within the lunch gives an actual assessment to exposing degrees. Depending on such assessment, good and effective solutions are possible. Through the research, a case study was evaluated using the previous process. The evaluation is followed with analysis. The research concluded with general recommendations and recommendations regarding the case study hold on long term and short term.