Reduction in evacuation time for tall buildings through the use of skybridges

Emergency evacuations during fires have historically been identified as a safety concern for super tall buildings. Stage evacuations and evacuations to a refuge floor were implemented as solutions, but after the World Trade Center tragedy, surveys showed occupants were unwilling to stay on refuge floors. This study proposes an alternative - horizontal evacuation using skybridges between towers taller than 200 m (656 ft.). Skybridges can reduce the chances of normal vertical downward evacuation routes being blocked and increase a building's evacuation efficiency without increasing the number of stairs. Linking up refuge floors in building clusters using skybridges would further reduce evacuation times. In this paper, we evaluate the skybridge design in terms of evacuation times in a typical 200 m (656 ft.)-tall building. Reductions in evacuation times are justified under three occupant loads. Empirical equations commonly used for performance-based design projects were used in the analysis, and the results were justified using evacuation software.