Simulation of a pediatric hospital in evacuation considering groups

Pedestrians will form groups in both normal and emergency sometimes. Members of these groups usually have certain social relations. We study emergency evacuation of pedestrians in a pediatric hospital in this paper. Pedestrians there have their own particularities. First of all, all patients are children. Secondly, the patients usually have no ability to see a doctor alone. They are always accompanied by their families. Thirdly, children of different ages move at different speeds, which is heterogeneous. Fourthly, pedestrians usually move in family units. Family units and independent pedestrians are also heterogeneous. According to our actual observations, pedestrians are mostly composed of three-person groups, two-person groups and independent ones. Each group usually has one leader and the rest are followers. We use an extended cellular automata model considering groups to study such evacuation. The rule of both overlapping and speeding up are set in the model to realize the change from heterogeneous to homogeneous from the view of speed. The local density field and its range R are introduced. The field can lead pedestrians move to the area with low density. The range R = 4 is optimal because of the family relation. The priority order is added to avoid conflicts. Groups with child have priority over independent pedestrians. The cohesive distance between leader and follower ensures members of the group always stay together, but the shape of the group is changeable in simulations. The evacuation time, waiting time and path of each pedestrian are analyzed. The simulation verifies the phenomenon that pedestrians behind tend to follow the front. The rules together release more free space to drastically reduce evacuation time and waiting time of groups, but independent pedestrians are not influenced greatly.