emergency staircase; fire escape
Refers to an external or internal staircase designated for emergency evacuation, commonly found in buildings.
Please use the emergency staircase in case of fire.
This building has two fire escapes.
避難階段 is a more technical term for evacuation staircase, often used in building codes, while 非常階段 is the common everyday term.
Compound of 非常 (emergency) and 階段 (stairs, staircase).