# Analysis of the Efficiency of Slope Evacuation for Dense Crowds in Urban Street-Type Public Spaces
## 1 Introduction  
China's urban development has entered a new stage characterized by the renewal and optimization of existing spaces. Tourism and leisure streets have become some of the most dynamic carriers of urban revitalization, contributing significantly to local economic growth. In the first half of 2024, the 164 national-level tourism and leisure streets received 875 million visitors, up 15.94% year-on-year [1]. The hot tourism economy has injected vitality into the economic development of various regions, but the risk of crowd gathering brought about by such large-scale festivals cannot be ignored. Tourism and leisure streets and other street-type spaces are characterized by frequent, continuous, and dynamic flows of people, and large-scale passenger flows can cause scenic spots to be overloaded, increase the risk of crowd gathering, and even cause sudden stampede accidents [2]. The Itaewon stampede in South Korea is a typical example of this problem: 159 people died and 196 were injured during the Halloween celebrations on 29 October 2022, due to overcrowding [3]. However, such street-type spaces with slope characteristics are not unique to South Korea. For instance, in the historic city of San Francisco in the United States, many streets have significant slopes. The steep slopes of Lombard Street, known as the \"crookedest street in the world\", not only pose challenges to traffic flow but also affect pedestrian movement during peak tourist seasons [4]. In Hong Kong, China, the unique geographical layout of the city has created numerous slopes, with a total of 29 downhill sections in the territory, including 12 on Hong Kong Island, 4 in Kowloon, and 13 in the New Territories. The gradient of these sections ranges from about 10% to 17%, and their length varies from about 500 m to 2000 m [5]. These areas face similar challenges with regard to slope stability, pedestrian access, and emergency evacuation. Scholars worldwide have carried out relevant studies on the mechanism of crowd stampede accidents from the aspects of stampede accident mechanism [6; 7], risk assessment method [8; 9; 10], simulation analysis of stampede accidents [11], and stampede prevention and management [12; 13]. Prior studies have focused mostly on crowd movement evacuation risks in large public spaces or building interiors. However, street-type spaces, which are relatively confined and feature unique spatial constraints, have received less attention in the literature. Furthermore, previous studies on pedestrian movement characteristics have focused on the case of evacuation on flat ground, overlooking the impact of sloped terrain. Sloped terrain can affect the walking mechanism of pedestrians and allow them to perform different behaviors [14]. Slope design is often required in urban roads as well as sidewalks to meet the need for accessibility, and a systematic study of the movement characteristics of pedestrians on slopes is an important guide for the design of such facilities. Unlike previous studies that focused only on crowd gathering or slope evacuation, this study focuses on the complex scenario of slope evacuation under dense crowd conditions, aiming to explore the influence of the coupling effect between complex crowds and special spatial structures on evacuation efficiency. On the basis of analyzing the mechanism of disaster caused by a stampede accident of a dense crowd on a slope in a street-type space, an evacuation model was constructed with a typical street-type space, Itaewon Numerical simulation experiments were carried out in terms of slope, street width, obstacle layout, disability types, and group movement, to analyze the rule of change in people's evacuation state during the evacuation process, and compare the difference in movement between different groups. The findings of this study are expected to offer a solid theoretical foundation for urban planners and designers to optimize the design and safety of street-type public spaces.