# Visualization of Emergency Evacuation Physical Behavior under Multi-Agent Decision-Making
## 4 Behavioral Evacuation Simulation Model Design and Analysis
### Exit Competitiveness for Evacuation Simulation Model Design
#### 4.3.2 Simulation Experiment Optimization and Result Analysis  
Since the bottleneck effect of congestion is caused by the sudden width reduction at the exit, this paper investigated the evacuation capacity of different corner radii at the exit on this basis. The right-angle-shaped exit channel was mainly changed to a circular arc channel with a radius of 1 m and a radius of 2 m. By establishing a detection line at each of the three model exit locations and comparing the right angle (r = 0) exit with two arc-shaped exits (r = 1 and r = 2) on the evacuation capacity and speed, the best exit setting method was obtained. After simulating experiments on the modified exits, the data obtained are shown in Figures 9 and 10, and the different corner radius settings have various effects on the evacuation situation. The improved model is significantly less crowded; the radius of the corner exit to complete the evacuation of all personnel time was reduced markedly, and the time consumption was the least of the three. The corner exit with a radius of 1 had a slight improvement relative to the evacuation capacity of the right-angle exit. The evacuation speed of personnel in the three different shapes of the exit channel was also significantly different and accelerated with the increase of the radius of the corner radius.  
Figure 8: (**a**) Capacity time map of different locations; (**b**) speed time map of different positions.  
Figure 7: (**a**) Setting diagram of the test line (the direction of the arrow is the direction of evacuation.) at the exit; (**b**) safety exit competition simulation experiment diagram (The coloured dots are multi-agent).  
To further improve the evacuation efficiency at the exit during the emergency evacuation, Figure 11a was used to complete the evacuation more efficiently by adopting specific evacuation flow lines for the evacuees. Three different evacuation flow lines were set up according to the evacuation flow from a single direction, which can divert and evacuate the congested people at the exit. The results show that evacuees can effectively reduce the congestion at the exit bottleneck when evacuating by setting up specific diversions of evacuation paths. From the comparison of the data in Figure 11b, it is clear that the evacuation effect is the same for both cases at the beginning of the evacuation, and when the bottleneck effect occurs at the exit with too many people, the capacity and efficiency of the exit with the set flow path were significantly improved compared with the original model.  
Both the corner curvature set up at the exit and the fixed flow line setup can reduce the bottleneck effect at the exit and improve the evacuation capacity and efficiency of the channel. However, that the installation of flow lines requires the introduction of fences and other equipment to divide the flow area, as well as the need for staff to guide the evacuation work to ensure that evacuees evacuate according to a specific flow line. However, in practice, this mode is not appropriate for the emergency evacuation of small places under unexpected conditions [43], and the results achieved in this way are not evident. Therefore, in the exit of non-large places, it should be chosen to improve the evacuation efficiency by setting the corner arc, while two optimized ways can be used together at the evacuation exit of large places.  
Figure 10: (**a**) Capacity time diagram of the three schemes; (**b**) speed time diagram of the three schemes.  
Figure 9: Simulation process diagram of the three improvement schemes (The coloured dots are multi-agent, the direction of the arrow is the direction of evacuation).