Distribution of the random variable of evacuation start time in aquathermal complexes during a fire

Purpose. The time from receiving a fire alarm signal to the start of people moving toward exits is called the evacuation start time. This period is necessary for recognizing the threat, making the decision to evacuate, and choosing the optimal path of movement. In fire safety regulations, this stage is described by two terms that refer to the same period but have different areas of application. The evacuation start time (tne) is used in calculations for the room with the fire source and depends on the area of the room. The time for preliminary actions preceding the start of evacuation (tprev) is applied to other rooms and depends on the functional fire hazard class, with only two values: (tprev) = 60 sec. for class F.1 and (tprev) = 30 sec. for other classes. It is evident that the evacuation start time depends on specific conditions. The authors selected aquathermal complexes as the subject of research, as evacuation from such premises is a more complex and lengthier task compared to, for example, a retail space. The existing theoretical calculation model proposes a synchronous start of evacuation (i.e., all people in the room begin evacuating simultaneously), but real-world practice shows that this is unfeasible. To determine the actual parameters of evacuation start time, the authors conducted two experiments in aquathermal complexes in the cities of Barnaul and Gorno-Altaysk. Based on the obtained data, statistical and theoretical processing was performed, enabling the creation of scientifically grounded recommendations for standardizing evacuation start times. Methods. The authors conducted an experimental study aimed at examining the time taken from the fire alarm signal to the start of people moving toward exits. Findings. The study established the main parameters of evacuation start time in aquathermal complexes. A mathematical description of the evacuation preparation process improves the accuracy of calculation methods necessary for assessing human safety during a fire. It was experimentally determined that evacuation start times in such premises vary, forming a distribution (close to normal) that also depends on the presence of visible fire hazards. The range of evacuation start times in Experiment No. 1 was 15 to 76 s, while in Experiment No. 2, it was 31 to 112 s. Based on the obtained values, an empirically confirmed (with a small margin) range of evacuation start time distribution was established for hall-type premises with and without a fire source. Research application field. The experimental data can be used to improve the methodology for determining calculated fire risk values. Conclusions. The study leads to the following conclusions: 1) The actual evacuation start time significantly exceeds regulatory values. 2) The time taken to perform actions upon receiving a fire alarm signal is influenced by individual human characteristics. 3) The established uniform values of evacuation start time do not reflect real processes and lead to an underestimation of fire hazards.