Questioning the linear relationship between doorway width and achievable flow rate

This paper challenges the currently assumed linear relationship between doorway width and achievable flow. The current view is seen as a simplification that may lead to an overly optimistic view of the achievable flow rates. Analyzed data are presented in order to demonstrate the impact that the actual use of the doorway and its design can have upon the flow rate generated. These data are then supported by the use of numerical simulations to demonstrate the impact that this overestimation can have upon the design process. It is contended that the specific flow rate assumed for a doorway should take into consideration not only its width, but also the design of the doorway (i.e., the opening and closing mechanism) and how evacuees behave in response to it. The issues raised have implications for the governing codes/regulations, engineering guidance and on the development of future computational egress models.