Tunnel and metro

Because the overall engineering of tunnel and metro is set underground, normally it has only in-and-out two operating planes. So with the restriction of tunnel space, after fire, the flame and smoke cannot diffuse upward but to diffuse longitudinally, the tunnel will quickly be filled with smoke. Besides, the rapid development of modern transportation system seriously increase the risk of tunnel fire. So it is critical to take effective fire protection and extinguishment measures and design high effective fire extinguishing systems.