STUDY on FLOW and CONGESTION in STAIRCASES during PHASED EVACUATION in A HIGH-RISE BUILDING: Analysis based on the observational data of a real total evacuation drill

If a fire or other serious emergency occurs in a high-rise building, all occupants would be forced to evacuate the building under such an extreme event. Also, it is quite probable that many occupants in the building start to evacuate at the same time on this occasion. Further, the staircase would become very congested, if all occupants try to evacuate via a limited number of staircases concurrently. In such a case, it may cause considerable delay of the evacuation time or influence on walking speed of evacuees. To cope with this kind of simultaneous total evacuation, there is a method known as "phased evacuation", where occupants on a fire origin floor and the floor above will evacuate first and followed by other occupants in different floors to avoid congestion in the staircase. However, it is unclear how the phased evacuation is more efficient than simultaneous total evacuation, because there have been limited studies and data concerning this method of evacuation. To explore the potential availability of phased evacuation, this study analyzes the data obtained by video recording and measuring movement of evacuees during a total evacuation drill conducted in a high-rise office building in Tokyo.