## 2 Analysis of Influencing Factors
### Distribution and Relevance of Influencing Factors
(2) Residential population: As shown in Figure 6b, the residential population in the inner ring of Beijing is relatively small compared to that in the outer ring of the city, and the residents living in the inner ring have a smaller range of activities and mainly move more during the peak hours, which has a smaller impact on rail transit passenger flow compared to the working population. The flow of people near the rail transit station is the direct source of the station's passenger flow, which is the most important link affecting the station's passenger flow. As shown in Figure 7, the working population and the residential population show a positive correlation for the subway's passenger flow. The long-term mobility of the population directly affects the planning and design of rail transit stations in the coming decades. Attractive features. (1) POIs (Points of Interest): Hospitals, schools, restaurants, and entertainment buildings around the rail transit station can each be abstracted as a geographic entity point and as the main destination for most travelers. The higher the density value of these points, the greater the number of people attracted, which brings a large number of passengers to the nearby rail transit station [28]. As shown in Figure 8a,  
Figure 6: Characteristics of the population. (**a**) Working population. (**b**) Residential population. Figure 7: Population characteristics and passenger flow correlation. stations located within the fourth ring road of the city center have relatively large POI values in their vicinity. This is also due to the fact that there are more people in the area who are engaged in different activities, such as working, going to school, going to the doctor, and having fun, which stimulates the development of local infrastructure, and, conversely, these facilities stimulate a large number of people to travel to these areas. (2) Percentage of residential area: The larger the residential area around a rail transit station, the larger the population, and the larger the number of residents, the more urban residents go to the rail transit station on foot or by bicycle, which brings a large number of passengers to the station. (3) Commercial area ratio: Commercial facilities are also mainly concentrated in the city center. The larger the area of the commercial area around the rail transit station, the greater the attraction of passenger traffic, thus attracting a large number of passengers to the station. As shown in Figure 8c, the number of commercial areas near the stations located in the southwest of the city center on Line 2, Line 4, the southeast of Line 2, Line 10, the northwest of Line 10, and the outer ring of Yizhuang Line is larger, and thus the passenger flow near the stations will be relatively larger. (4) The proportion of industrial area: Due to the special characteristics of industrial facilities, most of the industrial buildings in Beijing are distributed in the Outer Ring Road, and these industrial areas have a certain working population, and most of the staff will choose rail transportation as the main mode of travel, which also brings a certain amount of passenger flow to the nearby stations. As can be seen in Figure 9, the POI density value around the station has a greater impact on the metro passenger flow, showing a strong positive correlation. The correlation between commercial area ratio, residential area ratio, and passenger flow is weak. The ratio of industrial area does not show a linear correlation with metro passenger flow. Usually, building facilities will remain for a long time without special circumstances, but commercial  
Figure 8: Attractive characteristics. (**a**) POI. (**b**) Proportion of living area. (**c**) Proportion of commercial area. (**d**) Proportion of industrial area. buildings may close down at any time, which generates irregularity in population flow. The industrial buildings are located in the outer ring suburbs and other areas, the population is small, and the correlation with the passenger flow of rail transit is not strong.