The simulation and analysis of small group effect in crowd evacuation

• A novel methodology for calculating movement profit based on cellular automaton model is proposed.
• The small group effect and various velocities are considered in the evacuation strategies.
• This paper defines three types of small-group formation with totally six different forms of small group in terms of the size.

A crowd usually tends to move in small groups during evacuation. Small group has a large proportion in crowd evacuation, and small group effect affects crowd evacuation significantly. In this work, we propose a novel methodology for calculating movement profit based on cellular automaton model. Specifically, this methodology calculates the movement profit for a target at the next moment by comprehensively combining distance profit, density profit, and average velocity profit. In particular, this paper defines three types of small-group formation with totally six different forms of small group in terms of the size, and sets the corresponding movement velocity. At last, we simulate the evacuation process of small groups, and discuss the relationship among evacuation time, average movement velocity, and pedestrian density, and analyze the efficiency of small group evacuation in terms of evacuation strategies. As the simulation results demonstrated, the evacuation efficiency of different types of small groups is greatly different, and the same type of small groups with different forms is also different.