Basis for Egress Provisions in U.S. Building Codes.
Basis for Egress Provisions in U.S. Building Codes.
(1113 K)
Bukowski, R. W.; Kuligowski, E. D.
Volume 1;
Interflam 2004. (Interflam '04). International
Interflam Conference, 10th Proceedings. Volume 1. July
5-7, 2004. Organised by Interscience Communications
Ltd. in association with National Institute of Standards
and Technology, Building Research Establishment;
National Fire Protection Association; Society of Fire
Protection Engineers; and Swedish National Testing and
Research Institute, Edinburgh, Scotland, Interscience
Communications Ltd., London, England, 375-386 pp, 2004.
Keywords:
fire science; fire safety; evacuation; egress; building
codes; regulations; specifications; occupants; elevators
(lifts); stairways
Abstract:
Some of the earliest public safety-from-fire regulations
in the US are requirements for egress stairs -adopted by
New York City in 186d. One of the first model
regulations promulgated by the National Fire Protection
Association (NFPA) was the 1927 Building Exits Code,
predecessor of the Life Safety Code. Thus the need to
move occupants out of harms' way in building fires has
long been central to fire safety regulations.
The need to move occupants to a safe place was
underscored in numerous historical fire disasters.
Locked exits contributed to the high number of
fatalities (150) in the 1911 Triangle Shirtwaist Factory
fire and exit doors that opened inwards blocked by
crowds was cited in the 492 fatalities of the Cocoanut
Grove fire (1942)2. Incidents like these resulted in
public outcry for stronger code provisions but even
today egress problems leading to high numbers of deaths
persist. The 100 fatalities at the Station Club in Rhode
Island in 2003 provide the most recent example. Since
the Rhode Island fire, NFPA and other code authorities
are reviewing current requirements for level of safety,
especially for assembly spaces. These current
prescriptive codes used for building design contain a
list of egress specifications depending upon certain
aspects of the building, such as the type of occupancy,
the configuration of the space, the presence of
sprinklers, and the type of construction of the
building. These code specifications aid the designer in
providing a certain level of life safety for their
building, but little effort has been put into
quantifying this level of life safety in tenns of egress
times. This paper attempts to describe the prescriptive
design process for specific types of buildings.
Secondly, by applying some assumptions to the egress
specifications listed in the codes, an estimate of
resulting egress times for maximum occupant loads were
performed for specific occupancies. The egress times
were obtained using multiple calculation methods and
include estimates of pre- movement time, time to exit
the occupied room, and time spent to travel one flight
of stairs. Lastly, additional egress issues, such as
merging flows and the use of elevators for occupant
egress, are discussed.
Building and Fire Research Laboratory
National Institute of Standards and Technology
Gaithersburg, MD 20899