Simulation of a hospital evacuation including wheelchairs based on modified cellular automata

Hospitals are typical crowded public places with their complexities in China. It is very important to ensure the safe evacuation of all pedestrians in case of emergency. Wheelchair users have difficulties in evacuation because they need to occupy bigger space and cannot move easily. In this study, we conduct simulations for a hospital famous for orthopedics based on the modified cellular automata. Pedestrians here are divided into wheelchair users, general patients and normal persons. In particular, avoidance rules are set in the model to represent the moving priority of the wheelchairs. Local density field is introduced to improve the utilization of the movement space. Waiting time, evacuation time and movement routes are analyzed for these three types of pedestrians. The results show that the routes of wheelchairs are shortened and both their waiting and evacuation time are significantly reduced due to priority. The "slower is faster" effect is observed when normal persons and general patients actively avoid wheelchairs. Furthermore, interferences between different groups are obviously reduced and the evacuation efficiency is apparently improved because of the full use of the space. Wheelchairs are the weak part in emergency, so the priority to ensure the evacuation of such groups will improve the overall efficiency.