NIST: Elevators May Have High-Rise Fire Evacuation Role
December 13, 2007 // Published as a news service by IHS
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Experts are reconsidering tall building evacuation strategies and earlier this year, the National Institute of Standards and Technology (NIST) recommended code changes to increase elevator use in high-rise emergencies in the report of its three-year investigation of the Sept. 11, 2001 World Trade Center (WTC) collapses.
NIST will sponsor a conference - Rethinking Egress - in April 2008 to consider the benefits of elevator evacuations, including the advantages for persons with disabilities.
Depending on stairway evacuation alone can be risky, NIST fire prevention engineer Richard Bukowski said recently in London. "The time needed to descend undamaged and smoke-free stairs is about one floor per minute," he said.
"If the fire is on the 60th floor, occupants on that floor or above will spend one hour or more trying to escape the building. Escape from such a height can be exhausting for those in the best shape, let alone those who are elderly or have lower stamina."
Experts said it would take much more time or even be impossible to evacuate a building by stairs for those who need wheelchairs, walkers or crutches; for those with respiratory or cardiac conditions or who are obese; and for those with temporary conditions ranging from pregnancy to sprains.
Situations in which a person's wheelchair provides critical life support can also present additional problems. Such chairs are usually quite heavy and difficult for even several people to carry down stairs.
Elevator evacuation, however, would enable people with disabilities to self-evacuate with all the other building occupants. Elevator systems in modern high-rise commercial buildings are designed to move a building's entire population in or out of the building in one hour or less. In emergencies, elevators could be programmed to move those with the longest distance to go first. Occupants of lower floors (without disabilities) would have a choice to use the stairs.
During a total evacuation, elevators would collect occupants from the highest floors first, shuttle them to the exit level and return for another load, working their way down from the top. Pressing a call button would register people awaiting pickup but would not alter the sequence.
People with disabilities would not need to be given any priority since all occupants would be accommodated equally in this system. Experts said one elevator should be assigned exclusively to firefighters to provide rapid access to fires on upper floors.
Developers of U.S. building codes are considering proposals to require such elevators in tall buildings, and regulators in several countries are interested in requiring evacuation elevators as part of their disability regulations.
Source: National Institute of Standards and Technology (NIST).