Fire Protection Requirements for Metro Project Buildings Fire Resistance Grade of Metro Buildings (1) The fire-resistant grade of underground railway stations, sections, substations and other main projects, entrance and exit passages and air ducts shall be one- level. (2) The fire resistance of accessory buildings such as ground entrances and exits, wind pavilions, ground stations, elevated stations and elevated sections shall not be lower than the second grade. (3) The fire resistance level of the control center building should be one level. Fire protection zoning of Metro buildings (1) The public area of platform and Hall of underground station should be divided into a fire protection zone, and the maximum allowable area of each fire protection zone of equipment and management room should not be greater than 1500 m_. (2) When an underground transfer station shares a common station hall, the area of its public area should not be greater than 5000 m_. (3) When mechanical smoke exhaust is used in the public area of the station hall on the ground, the maximum allowable building area of the fire prevention zones should not be greater than 5000 m_and the maximum allowable building area of each fire prevention zones in other parts should not be greater than 2500 m_. Smoke prevention zoning of Metro buildings (1) Public areas of underground stations, as well as equipment and management rooms, shall be divided into smoke-proof zones, and smoke-proof zones shall not cross fire-proof zones. (2) The building area of each smoke-proof area in the public area of the station hall and platform should not exceed 2000 m_and the building area of each smoke-proof area in the equipment and management room should not exceed 750 m_. (3) The smoke-proof zoning can take measures such as smoke-proof vertical wall.The sagging height of smoke-proof wall and other facilities should not be less than 500 mm.