A New Method for Quantifying Exit Usage

During an evacuation from a building, the use of particular exits may vary significantly resulting in some becoming crowded while others are rarely used, which may cause inefficient egress. In this study, a new method of quantifying this varying exit usage and subsequently categorizing them into five different performance groups is proposed. This method is expected to allow us to compare the performance of exits in the same building as well as exits between separate buildings. To quantify the exit usage, the actual numbers of occupants using specific exits for a certain period are needed as well as the design occupant load and design number of occupants using the specific exits. The former values are obtained by actually counting occupants and the latter values are determined by exit design criteria, i.e., calculations found in building and life safety codes. Seven exits are selected from two buildings and their performance is compared quantitatively as a proof of concept. We hope these equations can be used in future research for the quantitative and qualitative study of exit usage.