Elevators Seen as Playing Hi-Rise Fire Evacuation Role
29-Oct-2007 8:50 AM EDT
Newswise — "In case of fire use the stairs, not the elevator" — appears on signs posted in elevator lobbies throughout the United States. In the aftermath of Sept. 11, 2001, however, experts are starting to reconsider tall building evacuation strategies. 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 World Trade Center (WTC) collapses, and next April NIST will sponsor a conference 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 observed in a recent talk in London.* "The time needed to descend undamaged and smoke-free stairs is about one floor per minute," he says. "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." However, it would take much more time or even be impossible to evacuate a building by stairs for some persons who need wheelchairs, walkers or crutches; for people with respiratory or cardiac conditions or obesity; 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 nor would the buttons in the elevator car. People with disabilities would not need to be given any priority since all occupants would be accommodated equally in this system. One elevator should be assigned exclusively to firefighters to provide rapid access to fires on upper floors.
U.S. building codes are currently 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. The NIST "Rethinking Egress" conference will be held in Gaithersburg, Md., in April 2008.
* R.W. Bukowski. Emergency egress strategies for buildings. By Richard W. Bukowski. Presented at the International Interflam Conference, London, England. Sept. 3-5, 2007.