In recent years, the number of kindergartens and the number of preschool children have been gradually increasing. Once an emergency occurs in kindergartens, preschool children are vulnerable to being injured. It is of great significance to investigate the characteristics of evacuation movement of preschool children in order to improve the evacuation efficiency and safety level of preschool children. However, current researches on pedestrian evacuation mainly focus on the evacuation characteristics of adults, while there are few studies on the evacuation characteristics of preschool children. Whether the obtained movement characteristics of adults is similar to that of children is still not clear. Bottleneck, as a typical structure of pedestrian facilities, has attracted extensive attention due to its constraint on pedestrian flow. However, there is still no consensus in the influence of the bottleneck on the pedestrian flow especially for preschool children.

Combined with the current literature, this work conducts controlled experiments to study the movement characteristics of preschool children evacuating through typical bottlenecks and analyzes the impact of bottleneck width on children’s evacuation efficiency, and compares the difference of evacuation characteristics between preschool children and adults. Based on the study of evacuation characteristics of preschool children, an agent-based model of preschool children passing through bottlenecks is proposed, and the empirical data are applied to validate the model. The influence of bottleneck width and the number of pedestrians on evacuation characteristics are studied by applying the proposed model.

First of all, this work carries out a laboratory experiment of high-motivated preschool children and adults evacuating through bottlenecks, and analyzes the evacuation characteristics of preschool children and adults from the perspective of movement conflict. This work observes that the spatial evolution of the speed can be divided into four stages: acceleration, deceleration, congestion, and reacceleration. The direction angle of evacuation movement is defined and the direction angle of evacuation changes from the stable small value in the initial stage to the larger value when the distance from the bottleneck is less than a certain threshold value. The spatial evolution of density is studied, and pedestrians with high motivation form a typical arch-like density distribution in front of the bottleneck. The clustering degree of preschool children is significantly higher than that of adults, and the peak density region formed by preschool children is closer to the bottleneck.

Secondly, from the evacuation efficiency of preschool children and adults passing
through the bottleneck, this work investigates several characteristic time – evacuation motion activation time in the initial evacuation, acceleration time in the process of evacuation and evacuation time at the end of the evacuation. Compared with adults, preschool children own longer evacuation motion activation time, lower acceleration ability and longer evacuation time. The bottleneck flow is linearly influenced by the bottleneck width. Under the same bottleneck width, the flow of preschool children is higher than that of adults, and the higher evacuation motivation helps increase the bottleneck flow. After considering the physical body size and evacuation motivation of preschool children and adults, the relation between flow and bottleneck width is well unified.

Then, based on the research on the evacuation characteristics of preschool children, this work constructs the ellipse field of the desired movement and considers the headway distance and visual field of pedestrians. An agent-based model of preschool children passing through bottlenecks is proposed. Considering the velocities and positions of other pedestrians and the positions of obstacles, the proposed model determines the pedestrian movement direction. The headway distance between pedestrians determines the pedestrian movement speed. The parameters of the model are defined by applying the cross-entropy method. The empirical data help to validate the proposed model. The model can well reproduce the evacuation process of preschool children passing through typical bottlenecks.

Finally, the proposed model simulates bottleneck evacuation scenarios by considering the influence of bottleneck widths and the number of pedestrians. The bottleneck flow shows a piecewise linear relation with the bottleneck width and the number of pedestrians. When the bottleneck width is higher than a certain threshold, the impact of the increase of the bottleneck width on the increase of flow decreases, and the increase of the number of pedestrians makes the flow first increase and then stabilize. When the bottleneck width is lower than a certain threshold, the increase of the number of pedestrians reduces the bottleneck flow until the flow is relatively stable. In this work, the model is applied to simulate the evacuation of a kindergarten, and the width of the evacuation door is optimized to improve the evacuation efficiency and reduce the degree of crowding.

The research on the movement characteristics of preschool children’s bottleneck evacuation in this work can provide help for the design of preschool children’s facilities and emergency plans. The proposed dimensionless analysis method of quantifying the relation between flow and bottleneck width well unifies the bottleneck flow of different bottleneck widths and evacuation motivation of pedestrians. The relation between pedestrian movement direction and distance can provide a data basis for the pedestrian evacuation dynamics model. The proposed agent-based model provides a common and effective method to assess the evacuation efficiency of the bottleneck structure.