Large Subway Station Research Articles

Predicting smoke temperature distribution beneath ceiling for a large subway station fire

Fire accident seriously threatens the stable operation and personnel security in the subway station, and clarifying the smoke temperature distribution is conducive to arranging reasonably fire alarm. In this study, model experiments and numerical simulations are conducted to investigate the ceiling temperature profiles, mainly altering the heat release rate (HRR) and fire locations in a large subway station. The repeatability of the experimental data is confirmed, and the numerical model is validated by the measurement data. During a fire happening in a large-wide space, the smoke movement beneath the ceiling can be divided into radial and one-dimensional flow, whose prediction models are proposed under fire source located at the center. On this basis, it can be found that the radial temperature profile is independent of fire source location. While, the one-dimensional temperature distribution model is modified by introducing the effects of transvers and longitudinal fire locations respectively. This work could provide data support and theoretical reference for clarifying the smoke movement for large subway station fire.

Numerical Simulation of Smoke Control Effectiveness with Different Exhaust Modes in a Large Subway Station

Abstract Fire smoke characteristics in the large subway transportation centre distinctly differ from others due to its complicated configuration and confined space. The smoke control effectiveness on different floors were studied with different smoke exhaust modes based on Shenzhen Che Kung Temple subway transportation centre by the method of large eddy simulation. The numerical simulation results show that high-temperature smoke is hard to gather due to the large space, and the effect of smoke control is obtained with different smoke exhaust and air supply modes. With the smoke exhaust volume specified by the relevant fire codes, the smoke spread in the basement can be effectively controlled, but the smoke movement in the sub-basement and third floor of underground are out of control. Meanwhile, some characteristic parameters such as smoke concentration, smoke temperature and visibility are effectively controlled by smoke exhaust and air supply of the entire region, and the smoke is better controlled in partial regions with smoke exhaust and air supply. Also, the smoke control effect in sub-basement is similar to that of third floor of underground.

Influence of soil liquefaction on the seismic response of a subway station in model tests

In this work, several shaking table tests are conducted to investigate the seismic responses of a large subway station in various liquefied soil conditions. Different liquefaction states are modeled for the soil foundation by inputting different earthquake intensities. According to the test results, when the lateral soil layer surrounding the underground structure is partly liquefied, the cumulative residual deformations of the subway station are much greater than those in either non-liquefied or completely liquefied ground, which is mainly as a result of the large unrecoverable lateral deformation of the partially liquefied ground. Additionally, when the surrounding lateral soil layer is completely liquefied, the subway station structure experiences significant uplift. When only the soil layer near the upper wall is liquefied, large residual dynamic soil pressures on the sidewall are observed at the end of the test. In addition, the strain distribution rules of the underground structure are clearly altered in the presence of different states of soil liquefaction. These new findings can be used as a basis for evaluating the seismic risk of large underground structures in liquefiable ground.

Seismic responses of a large underground structure in liquefied soils by FEM numerical modelling

A large underground subway structure could be severely damaged in a strong earthquake, such as the seismic damages of Daikai subway station in the 1995 Kobe earthquake. After the 1995 Kobe earthquake, the effects of earthquakes on underground structure became a hot topic. According to the seismic damage characteristics of the pipelines buried in the liquefiable soils, a large underground structure may be damaged ever more severely by the liquefaction. To examine the dynamic properties of saturated liquefiable soil, an existed constitutive model is revised and implanted into the commercial FEM software. Then the nonlinear seismic responses of large underground subway structures built in liquefiable soils are analyzed by a numerical modeling. The results of the comprehensive numerical analysis indicate that the existing subway station has a significant effect on the liquefaction of the nearby soils that are likely to be liquefied. The around sand soils under the suggested depth 20 m may be also liquefied under the influence of the large subway station, which should be non-liquefiable sand in many related codes of China. The subway station floats up as soon as the nearby soils are liquefied, and the soils accordingly flow from the lateral foundation to the bottom foundation of the subway station. It is also found that the floating of the subway station is completely out of sync in the main vibration stage of the inputted ground motions and the rising stage of the pore pressure, and it also lags behind in the main vibration stage for a considerable time and begins to stabilize only when the vibration weakens sharply and is close to zero. Generally, the dynamic softening soils under the subway station also have great effect on the seismic response of the large subway station.

An Experimental Study on Evacuation Times in a Subway Station Using Evacuation Parameters

In this study, 292 participants took part in the evacuation experiment and completed a questionnaire. The study was conducted in a large subway station in order to analyze evacuation times during a fire, and used different evacuation parameters. The subway station where the experiment was conducted consisted of two basement floors. The evacuation started as soon as the train, in which a fire had occurred, came into the subway station and the doors were opened. The entire process of the evacuation experiment was recorded by using video cameras installed in the subway station. After the evacuation experiment was completed, participants were asked to answer questionnaires on evacuation parameters such as; gender, whether they had companions, how well they know that particular station, their usual level of awareness of evacuation, and their level of evacuation knowledge. By analysing the survey results, the time of egress from the train, and the total evacuation time, the results were as follows. 1) Female participants were slower by 23% on average compared to male participants. While male participants evacuated according to an order of egress from the train, female participants were affected by many other factors during evacuation.2) Those who had companions were slower in evacuation by 29% on average compared to solo evacuees. 3) Knowledge of the area helped both female and male participants during the evacuation. The delay in evacuation according to a lack of knowledge of the station was only 9% in the case of male participants, but 21% in the case of female participants. 4) Those who did not usually think about evacuation were slower to evacuate by 8% on average than the other group who had a good level of awareness. 5) Those who did not have any knowledge of evacuation were slower by 18% on average than the group who had a high level of evacuation knowledge.

A spatial topological routing solution for emergency responding in 3D subway area

With the fast expanding of cities, people spend more time on travelling among complex built–up areas such as large subway station. When the emergency event appears, people need a routing method that provides the optimised path fast and a path–finding solution that utilises spatial topological relationship to finish the inner building routing is sounding for this task. The introduced 3D spatial routing solution divides a specific routing problem into several minor routing problems across the related spatial regions to acquire optimised performance. The experiment shows that the spatial relationship introduced into solution increases the speed of the whole route generation significantly, and still maintains a high quality of the path–finding results. In conclusion, the proposed solution has represented a new meaningful approach to apply spatial topological relationship into emergency path–finding solutions for subway areas.

An evaluation of the signposting system in a large subway station : Arnegard, R.J., Hammontree, M.L., Montgomery, M.J., Pearson, G.L., and Zwaga, H.J.G. In: Perspectives. Proc Human Factors Soc 33rd Ann Meeting, Denver, Colorado, 16–20 Oct 1989. Human Factors Soc, Santa Monica, California, Vol 1, 1989, pp 541–545, 4 refs

An evaluation of the signposting system in a large subway station : Arnegard, R.J., Hammontree, M.L., Montgomery, M.J., Pearson, G.L., and Zwaga, H.J.G. In: Perspectives. Proc Human Factors Soc 33rd Ann Meeting, Denver, Colorado, 16–20 Oct 1989. Human Factors Soc, Santa Monica, California, Vol 1, 1989, pp 541–545, 4 refs

An Evaluation of the Signposting System in Large Subway Station

The purpose of this study was to objectively evaluate the signposting system within the Metro Center subway station of the WMATA (Washington Metro Area Transit Authority). The approach taken was: first, to estimate the prevalence of passenger behaviors indicative of deficiencies in wayfinding; second, to evaluate the adequacy of the signposting within various decision areas of the station; and finally, to evaluate the individual components of the signage system. The first objective was addressed by observing 507 passengers selected via a pseudo-random sampling technique. From this sample an overview of traffic patterns was developed and it was determined that roughly 7% of these passengers followed a route that did not comply with the directions provided by the stations sign posting system. It was further found that an additional 2% asked for direction. These figures were combined with data provided by the WMATA to project that 6,000 to 7,000 of the passengers disembarking a train within Metro Center will evidence some form of inefficient wayfinding behavior each day. To address the second question portions of the randomly sampled data were combined with data gathered from a selectively sampled group of passengers operationally defined as needing wayfinding assistance (n = 359). This data was analyzed to determine the relative difficulty that information needy passengers had in finding their way through the various areas of the station. The final objective was addressed by comparing individual components of the signage system to current human factors guidelines.