Aim: The purpose of this article is to show how a representative middle-aged group of people tend to behave during the implementation of an evacuation procedure in a given public building.

Introduction: This article describes factors which, influence people’s mobility in extreme circumstances, such as: the sounding of a fire alarm or bomb alert in a building. The article defines the term “crowd” but also illustrates potential behaviour of middle-aged group of evacuees. Data, specifically calculation models are, in the main, employed to determine the maximum lead time necessary for safe evacuation of a building - exit a building to a safe location or an adjacent fire free zone. Calculations, because of simplification, are quick and straightforward but, in the main, ignore human behavioural aspects during evacuation. After sounding of a fire alarm one can observe a range of reactions such as: completion of work in progress, collection and packing of personal items, a search for family members, attempts to extinguish fires, people gaping at what is going on, others exploiting the confusion with theft attempts and other happenings which, extend the evacuation lead time and negatively impact on the safety of people.

Conclusions: Simplification of calculation models and lack of due regard to human behavioural aspects, during an evacuation, may contribute to a significant divergence from realistic time requirements necessary to vacate a building.

Relevance in practice: The described experiment, conducted in a high rise building, in the city of Łódź, illustrates most frequently observed behaviour of people during an evacuation practice. The experiment did not incorporate an evaluation of behaviour or duration of an evacuation involving disabled people. The experiment outcome was compared with Pathfinder, a computer simulation programme and currently most frequently used calculation model described in this article. This facilitated a deeper insight into calculated evacuation lead times using a range of engineering tools harnessed in fire safety. The experiment also allowed for the verification of individual phases of the conceptual simulation model, highlighting distinctive phases such as: perception, interpretation, decision making, and direct action during an evacuation.

Keywords: human behavior, evacuation, crowd, crowd behaviour, experiment

Type of article: case study