HUMAN BEHAVIOR IN EVACUATION
Evacuation from buildings is not only about measuring the time needed to exit or emergency exits’ width. Indeed, actors of the evacuations are human beings that are affected by social and psychological processes that affect the exit from the building. This chapter will start with a brief explanation about what an evacuation is, of the different classifications used over the times and some information about Italian legislation about evacuation. Then, the two main models of human behavior in evacuation developed by Kuligowski (2008) and Galea, Dreere, Sharp, Filippidis and Hulse (2010) will be presented in detail. Later, some findings from the literature about decision making in evacuation will be reported. Lastly, the final section will provide an integrative model of factors playing a role in the evacuation process.
“Evacuation is the primary protective action utilized in large-scale disasters such as hurricanes, floods, tsunamis, volcanic eruptions, releases of hazardous or nuclear materials, and high-rise building fires and explosions. Although often precautionary, protecting human lives by withdrawing populations during times of threat remains a major emergency management strategy” (Sorensen & Sorensen, 2006, p. 183). Evacuation refers to the withdrawal actions of occupants from a building or generally people from a specific area because of a real or potential hazard. The time needed to evacuate can vary from a few seconds to minutes or hours, depending on several factors connected to individuals, hazards and the area’s or building’s characteristics. Nevertheless, speed is the key factor in evacuations: the faster occupants understand the need to evacuate and move quickly to the safe place, the more successful the evacuation will be. Incident analyses have shown that a delayed evacuation results in a larger number of fatalities (Fahy & Proulx, 2001). The first studies about evacuation identified 4 different types of evacuations (Drabek & Stephenson, 1971):
- invitation – someone outside the area of risk or the building provide the means or urge to leave,
- choice – individuals processing warning information, deciding to leave and then taking action,
- default – involves behaviors dictated by actions other than seeking safety from the hazard,
- compromise – people following orders even if they don’t want to or don’t feel it necessary to leave.
Other authors chose to classify evacuations by crossing two dimension of evacuation: timing and period of evacuation (Perry, Lindell & Greene, 1981). They distinguished between:
- preventative – pre-impact and short term,
- protective – pre-impact and long term,
- rescue – post-impact and short term,
- reconstructive – post-impact and long term.
Ronchi and Nilsson (2013) categorized the different egress strategies from a building into 4 types:
- total evacuation – it occurs in case of evacuation of all occupants at once from the building to the designated area of safety. The application of this strategy strongly depends on the use of the building, its characteristics, and the number of occupants. phased evacuation – when the first strategy is not practical and there is the necessity to control and optimize occupants flow, groups of people can be evacuate in different time, with priority of who is nearer to the hazard (especially in case of fires). This solution works only if there are effective means of communication within the building, trained staff and safety equipment available in the building.
- defend-in-place – when evacuating is too risky, or in case of people with disabilities, sheltering can be the best strategy. A key aspect in this case is the communication between the rescuers and the rescued that has to be efficient for the operation’s success. ? delayed evacuation – it takes place when evacuees are temporarily waiting in dedicated areas in order to be reached by rescuers. Also in this case, this strategy is useful in case of occupants with disabilities or for health care facilities.
Italian legislation about evacuation considers some norms to manage fire emergencies, exposed in the Decreto Legislativo 81/08 art. 43 DM 10/03/98. It establishes that inside each productive activity, such as factories, offices, plants or public administration, must have an emergency and evacuation plan. This plan is made by both the employer and the RSPP (Responsabile del Servizio di Prevenzione e Protezione, literally translatable in responsible of the protection and prevention service) and must include at least the following points:
- business activity description,
- recognition of the persons involved in the emergency management,
- recognition of the risks connected with the environment or the activity,
- recognition of the preventive or protective measures present,
- fire load calculation,
- fire risk classification (high, medium, low),
- evacuation manners, ? safe places indication,
- indication about the fire equipment controls,
- emergency management, ? drills register.
Italian legislation doesn’t provide special norms for evacuation in case of earthquake, but most of the schools, factories, companies or even trade unions offer special evacuation plan in case of earthquake (for example the document “Linee Guida per la tutela della Sicurezza e Salute dei lavoratori a seguito di Evento Sismico” from CGIL Pesaro).
© – MANAGEMENT OF AN EMERGENCY EVACUATION: A LEADER’S PERSPECTIVE – Sara Colangeli