NIST Time|NIST Home|About NIST|Contact NIST

HomeAll Years:AuthorKeywordTitle2005-2010:AuthorKeywordTitle

Basis for Egress Provisions in U.S. Building Codes.


pdf icon 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.