With the development of the city and explosion of population,
the public transportation is strongly recommended because of its
advantages on the aspects of energy conservation and environment
protection. In all the public transportation, the metro rail system is
the most efficient in terms of energy consumption, space
occupancy and numbers transported. In the metro rail system
there is a high concentration of passengers such that any potential
dangers may cause them to be at risk. In particular, if a fire occurs
in a tunnel which is the most serious potential danger, it may be
very difficult for passengers to evacuate within the toxic fire smoke
in the tunnel.