Monte Carlo Agent-Based Hospital Evacuation Simulations. The Principles Of Performance-Based Inclusive Design

In emergency, while the majority of the occupants recognise the risk and start the evacuation process autonomously, the people who need assistance do not necessarily act in that way. Trained and skilled staff is required to rescue those needing help, avoiding the risk of discriminatory response and failure. A few modelling approaches are available to assess the egress of people who need assistance to evacuate, since both physical and cognitive aspects should be considered. In this study, an agent-based approach has been adopted with a focus on the behavioural rules assigned to the agents depending on their characteristics and goals. A unified framework is proposed to establish a standard codification of the occupant profiles: based on their mobility and way-finding abilities, occupants are classified into a basic set of five categories. For each occupant category, the mobility device and the staff assistance eventually required are specified. Apart from occupant characteristics, it is necessary to define the service discipline. consisting of three components: the staff skills and consistency, the scheduling policy, and the mobility device eventually required to relocate the assisted occupant. The movement of people as groups is also considered. The inclusive approach proposed in this study has been implemented using the Pathfinder software and applied to the analysis of the assisted evacuation scenario of a hospital ward. In order to demonstrate the ability to simulate complex evacuation plans, the horizontal relocation of the patients to refuge areas located on the same floor is combined with the vertical transfer using firefighters lifts. The stochastics variables representing the occupant characteristics and the service discipline have been described by probability distributions, including both autonomous and assisted profiles. The Monte Carlo methods provide the means to address the parameter uncertainty in probabilistic risk analysis. Based on the Central Limit Theorem, the number of trials required for a specified accuracy in the evacuation time modelling is obtained using a predictor-corrector scheme applied to the worked case. The principles of performance-based inclusive design are thus established, with proper consideration of the occupants who need assistance, the assisting staff role and the service discipline. This approach can be considered a generalization of the conventional Required Safe Escape Time (RSET) evolving into the Required Safe and inclusive Escape Time (RiSET).