# Analysis of the Efficiency of Slope Evacuation for Dense Crowds in Urban Street-Type Public Spaces
## 6 Discussion  
This paper investigates the effects of different terrain features (slope, road width, obstacle layout) and group movement (disability type, group size, age composition) on evacuation, carries out evacuation simulation experiments for crowds of different densities, obtains various types of evacuation indexes, and carries out a comprehensive analysis of  
Figure 14: Group configuration illustration. Figure 15: **(A) Effect of age composition when group size is 2; (B) Effect of age composition when group size is 3. **the pattern of change in the crowd's evacuation state and behavioral characteristics in the process of going downhill. Current research suggests that pedestrians move faster downhill than on level ground on slopes less than 4\({}^{\circ}\), and that excessive slopes reduce the speed of pedestrian movement. Previous research [18; 20; 21] provides strong support for this conclusion. This can be interpreted as when the slope is small, the downward component of gravity acts as an additional driving force for pedestrians, facilitating their walking process. However, when the slope is large, pedestrians have to counteract the excessive acceleration caused by gravity by providing sufficient friction in the opposite direction of advancement. When the slope is the same as the Itaewon stampede site at 7\({}^{\circ}\), the extreme points of the curves are especially obvious when the crowd density is greater than 1.00 pedestrians/m\({}^{2}\), further indicating that the coupled effect of slope and crowd density is an important cause of the accident. From the application point of view, in urban planning, the maximum slope of public space slopes should be designed within the safety range (less than 4\({}^{\circ}\)), and controlling the slope angle can improve the stability of walking during pedestrian evacuation and reduce the risk of accidents. For existing street-type spaces with steep slopes, anti-skid facilities, and additional handrails can be installed to help pedestrians overcome the effects of gravity and improve walking safety. We study the effect of field of view opening on pedestrian evacuation by changing the width of the road. The simulation data show that when the street width is less than 6 m, the field of vision of pedestrians is restricted to a very limited range, the spatial scale of human activities becomes narrower, and pedestrian evacuation is significantly affected. The narrow field of view not only physically limits the observation range of pedestrians but also psychologically causes stress and hesitation. Pedestrians may become more cautious and make frequent adjustments to their walking direction, which in turn reduces the overall evacuation efficiency. Therefore, the ratio between the street width D and the building height H on both sides should be carefully considered when designing the spatial scale of the street. When D/H! 1, the visual space is limited, and the street space is high and narrow [17]. Measures such as widening the street or appropriately lowering the building height can be taken to improve the visual space for pedestrians. For existing streets with spatial scale D/H! 1, such as Itaewon Street, traffic control and clear guide signs can be used to direct pedestrian flow and improve evacuation safety. Obstacles can cause pedestrians to fall or be injured. This not only affects the safety of individual pedestrians but may also result in subsequent pedestrians not being able to cross in time due to congestion. In this study, obstacles are set up in the street space according to seven layout patterns. The evacuation effects are in order of accessibility, middle of the street, street sides, and mixed layout. Meanwhile, in the simulation process involving obstacles, the phenomenon of some pedestrians being stranded and unable to evacuate exists; the higher the number of stranded people, the higher the level of collision risk.