Final answer:
The fire rating of materials used in the construction of metro stations is not specified here, but these materials are generally non-combustible to prevent fire hazards. The question alludes to historical practices, exemplified by the construction of the Brown Building, which showcased significant safety flaws despite being deemed 'fireproof' at the time.
Step-by-step explanation:
The construction of metro stations involves specific safety considerations, especially regarding materials used in their design. Metro stations are typically constructed of non-combustible materials to prevent the spread of fire, which could be catastrophic given the enclosed nature of these spaces and the number of people they serve. However, the question about the specific fire rating these materials must meet is not explicitly answered here.
The historical context of the question may relate to the Brown Building, which was considered "fireproof" at the time of its construction in 1901 due to the use of steel and iron. Nonetheless, the building had serious flaws such as limited bathrooms, inadequate ventilation, dark and dangerous stairwells, no overhead sprinklers, and a substandard fire escape. Within the context of the Triangle Shirtwaist Company, which occupied its upper floors, these issues were compounded by the presence of flammable materials and close-working conditions, all of which contributed to a high fire risk.
Modern safety standards would not allow for such conditions, and the required fire rating for materials used in high-risk environments like metro stations would be much higher to ensure the safety of occupants. TheBrown Building serves as a case study for the evolution of safety standards in public building construction, emphasizing the importance of using properly rated, non-combustible materials to protect against fire hazards.