Stair Evacuation Simulation Based on Cellular Automata Model Considering Social Forces

Building evacuation in case of emergencies has long been recognized as a crucial issue, especially for the stair evacuation because evacuees may spend most of the evacuation time in stairs. To predict the evacuation time in stairs, simulations are commonly used, but known simulations ignore the stair structure and the fact that people may change their speeds during evacuation. As a result, how to introduce a reasonable mechanism on how evacuees change their speeds and improve the stair evacuation simulation are important. In this paper, a new Cellular Automata (CA) model where a new grid map is introduced based on the stair structure, and then the interaction among evacuees can be simulated better than the existing CA simulations. To make a reasonable mechanism of changing speed, the social forces will be introduced to the new CA model based on the advantages of social force models. However, social force model is a continuous model and CA model is a discrete model, and there is a gap to use social forces directly into a discrete model. To bridge the gap, the system time interval is shortened, and then evacuees have variable speeds by updating their positions during several intervals. To validate this simulation, an experiment was held in a high-rise building. In the fire drill, harmless smoke was released to make the drill similar to real events. The simulation results are similar to the fire drill data by comparing evacuation time.