Application of the social force modelling method to evacuation dynamics involving pedestrians with disabilities

With the development of urban architecture, the growing demand for larger public buildings is becoming challenging for indoor human evacuation under emergencies such as fires. However, the indoor fire evacuation behaviour of heterogeneous crowds when including individuals with disabilities have not been adequately explained. Therefore, this paper aims to study indoor evacuation characteristics of a crowd involving individuals with different types of disabilities (i.e., individuals on crutches and wheelchair users) through a modified social force model. The computation and simulation is performed in a room with an exit in 15 scenarios involving varying number of agents (i.e., 20, 40 and 60). The real-time trajectories and coordinates of agents are obtained. It is found that with an increase in the proportion of pedestrians with disabilities, individual evacuation time of agents increases. This tendency is consistent with results obtained from a previously controlled experiment. The average evacuation speed of agents is negatively impacted by the mixture proportion of individuals with disabilities. The fundamental diagrams acquired from the simulation are similar with the experimental results. Furthermore, it is discovered that the presence of individuals of disabilities in a scenario triggers higher crowd pressure compared to scenarios involving all non-disabled individuals. With an increase in the proportion of pedestrians with disabilities, the crowd danger of agents increases, as also consistent with the experimental findings. These findings are helpful for computer-aided safe evacuation design to decrease heterogeneous crowd congestion during in-building fire evacuation.