Where drills differ from evacuations: A case study on Canadian buildings

Planned egress drills are required by building codes around the world, and are commonly used to both train occupants and assess evacuation procedures. However, capturing the idea of a “successful” drill is often difficult. Data from both drills and unplanned evacuations are often incomplete and unreliable, which raises a key question: How well-matched are planned egress drills and unplanned evacuations in terms of their properties and outcomes? That is, are drills a good model of evacuation? In this paper, we compare 93 planned egress drills and 23 unplanned evacuations, which occurred in Canadian office buildings over a span of four years. Our two main findings are that (1) planned egress drills differ from unplanned evacuations in terms of frequency, timing, and outcome (e.g., reported total evacuation time), and (2) the reported number of occupants correlates with total evacuation time. These findings motivate a discussion of the strengths and weaknesses of the current approach to data reporting, and we highlight potential implications for (and limitations of) the current drill model.