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Questioning the Linear Relationship Between Doorway Width and Achievable Flow Rate



Steve M. Gwynne, Jessica Kratchman, Erica D. Kuligowski, James A. Milke


This paper suggests that the currently assumed linear relationship between exit width and achievable flow is a simplification that may lead to an overly optimistic view of the achievable flow rates. Analyzed data is presented from several sources in order to demonstrate the impact that the actual use of the exit and its design can have upon the flow rate. This data is then supported by the use of simulation work in order to demonstrate the impact that this overestimation can have upon the design process. It is contended that the specific flow rate assumed for an exit should not only take into consideration the width of the exit, but the design of the exit (i.e. the opening mechanism of the exit) and how evacuees behave in response to it. The issues raised may have implications for the governing regulations, engineering guidance and on the development of future computational egress models.
Fire Safety Journal


door, effective width, egress models, exit, flow rate


Gwynne, S. , Kratchman, J. , Kuligowski, E. and Milke, J. (2009), Questioning the Linear Relationship Between Doorway Width and Achievable Flow Rate, Fire Safety Journal, [online], (Accessed May 23, 2024)


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Created December 31, 2008, Updated October 12, 2021