Elevator evacuation

"In case of fire use the stairs, not the elevator."

Signs like this are posted in high-rise elevator lobbies throughout the United States. In the aftermath of Sept. 11, 2001, however, emergency planners are beginning to rethink tall building evacuation strategies.

“For years we have been advising people that elevators are not safe, and cannot be made safe, to use during fires,” says Richard Bukowski, a fire engineer at the National Institute of Standards and Technology. But that rule may be about to change.

(AP Photo/Joseph Kaczmarek)

Early last year, in a report of its three-year investigation of the World Trade Center collapses, NIST recommended code changes to increase elevator use in high-rise emergencies. Elevators have traditionally been reserved during fires for high-rise firefighting protocols.

“The time needed to descend undamaged and smoke-free stairs is about one floor per minute,” Bukowski says. If the fire is on the 60th floor, occupants on that floor or above will spend an 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,” he comments.

This April, NIST is sponsoring a conference to evaluate the benefits of elevator evacuations. How many elevators and what size, the arrangement of egress stairs, horizontal exits, areas of refuge and refuge floors (as used in Asia) are all on the table.

“NIST and many others recognize that a change to elevators as the primary means of egress from buildings represents a major paradigm shift and will require a rethinking of egress,” Bukowski says.

Bukowski believes that by using available technology, we can provide elevators that permit self evacuation of all occupants — including those with disabilities — in one hour or less from any building of any height without increasing the number, size or speed of the elevators normally provided. As buildings reach record heights (Burj Dubai has just passed floor 158), there is no alternative to elevator egress, he says.

Protected elevators are so attractive to designers and owners of ultra-tall buildings that there are virtually no building under construction or planned for a height over 1,000 feet that do not use protected elevators designed to the specifications discussed in NIST’s published papers.

“It''s not a question of making it happen, at this point it cannot be stopped,” Bukowski says.