# Analysis of the Efficiency of Slope Evacuation for Dense Crowds in Urban Street-Type Public Spaces
## 3 Risk Analysis of Crowd Gathering on Slope in Urban Street Spaces
### Mechanism of Slope Stampede Formation in Street-Type Public Space  
According to the chain process to categorize the street-type public space slope stampede risk into three stages: pre-accident period, accident evolutionary period, and consequences of the accident, as shown in Figure 2. By focusing on weak links, emergency managers can improve the system of emergency response systems.  
Figure 1: Schematic diagram of the forces on the pedestrian’s slope movement.  
1. Pre-accident period: During the holidays, the number of tourists to be received at major tourist attractions multiplies, causing a large number of people to spontaneously converge in the street-type field. The narrow spatial characteristics of the street space tend to lead to poor visibility for pedestrians and chaotic conflicts with multi-directional pedestrian flows [17]. Adverse weather conditions, such as rain and fog, can have a significant impact on pedestrian behavior. Pedestrians' perception of safety is disturbed by weather factors. For example, in low visibility conditions, pedestrians' cognitive abilities may be affected since the capabilities of visual and auditory cognitions of the environment are reduced [26]. Poor light quality, especially in the evening or in poorly lit areas, further impairs pedestrians' ability to assess the safety of their surroundings and avoid collisions [27]. Additionally, the presence of obstacles or temporary facilities blocking pedestrian paths exacerbates congestion by creating bottlenecks [28]. The density of the crowd in this stage is relatively low, and the crowd is still able to move freely, but the number and density of the crowd are on the rise. 2. Accident evolutionary period: As the density of the crowd increases, the movement of the crowd is progressively restricted, especially under the compounding effects of poor weather or lighting conditions. When the flow of people gradually reaches the capacity limit of the space, the phenomenon of stagnation and congestion occurs. When the flow of people in the field exceeds the critical value, irrational competition for space and time triggers pushing and showing [29; 30]. The presence of obstacles exacerbates the creation of bottleneck areas, while the panic caused by the rapid spread of rumors further accelerates the deterioration of the situation [31]. 3. Consequences of the accident: Stampede accidents cause serious casualties and damage to public facilities. Poor lighting conditions can make evacuation difficult, impede rescue operations, and increase the psychological stress for trapped people. Excessive psychological stress on the crowd may lead to mass riots or disturbances, with lasting  
Figure 2: Mechanism of slope stampede formation in street-type public space.  
effects on the individuals and communities involved. With the rapid intervention of evacuation, rescue, pacification, investigation, and public opinion response, the incident gradually subsided and the authorities began to identify the cause and restore order, allowing the incident to enter the final phase.