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Abstract
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Background
Understanding how subway tunnels perform during accidents or malicious attacks resulting in the release of smoke or hazardous toxins is key in establishing evacuation strategies that reduce the loss of life or effects on public health. During such emergency situation, the natural background air current caused by the air exchange between the station and outside, has an important influence on the dispersion of smoke and/or toxic agents. Over 60% of deaths in fires are caused either wholly or partially by inhalation of smoke or toxic gases. Thus evacuation strategies that provide routes which reduce the exposure time of individuals to a toxic environment could potentially reduce the loss of life or effects on an evacuee's health. The strategy "go up and take the nearest exit to the surface" might not be the best response. To support this assessment an understanding of; the air flow driving the motion of smoke, its links with internal climatology and external weather conditions and the evacuation capabilities of subway tunnels, is needed.
Methods
To support this exploration, 3D Computational Fluid Dynamic models have been developed, to validate field measurements and to gain an understanding of the internal airflow momentum and energy transfer capacity of subway stations in relation to external climatic factors and its effect on the dispersion of smoke and/or toxic agents. By integrating results with evacuation simulations, visual diagnostic and predictive tools which display; the background air flow within the subway, the dispersion of smoke and/or toxic substances, the resulting reduction of visibility and the evacuation of pedestrians, are in development to further our understanding in both subway climatology and integrated evacuation strategies.
Results
Initial results show promising links between external climatic factors, the subway climatology and the ability to predict the dispersal of smoke/toxins. It has also been established that by navigating pedestrians on routes away from smoke and/or toxic dispersion can significantly reduce the number of fatalities and effect on evacuee's health. The possibilities of integrating these findings is allowing for a more integrated assessment to be carried out.
Conclusions
The study discussed demonstrates that by integrating the datasets mentioned, a greater understanding of the effect subway climatology has on evacuations strategies of subway stations can be understood. It is shown that accessible technology and software, along with methodologies developed, supports the assessment and development of integrated evacuation strategies that reduce the loss of life or effects on public health.
Language: en |