Occupant descent down stairwells during building evacuations is typically described by measureable engineering variables such as stairwell geometry, speed, density, and pre-evacuation delay. In turn, predictive models of building evacuation use these variables to predict the performance of egress systems for building design, emergency planning, or event reconstruction. As part of a program to better understand occupant behavior during building emergencies, the Building and Fire Research Laboratory at the National Institute of Standards and Technology (NIST) has been collecting stairwell movement data during fire drill evacuations of office buildings. These data collections are intended to provide a better understanding of this principal building egress feature and develop a technical foundation for future codes and standards requirements. To date, NIST has collected fire drill evacuation data in 8 office building occupancies ranging from six to 31 stories in height that have included a range of stairwell widths and occupant densities. While average movement speeds in the current study are observed to be quite similar to the range of literature values, local movement speeds as occupants traverse down the stairwell are seen to vary widely within a given stairwell due to crowding or occupant mobility. These data should provide confirmation of the adequacy of existing literature values typically used for occupant movement speeds or provide updated values for future analyses.
Citation: Safety Science
Pub Type: Journals
evacuation, egress, fire safety, modeling, theory