Core Viewpoint - The article discusses the recent surge in subway ridership in major Chinese cities, particularly Guangzhou and Shenzhen, highlighting their entry into the "10 million passenger club" alongside Beijing and Shanghai, indicating strong urban vitality and infrastructure development [4][11]. Group 1: Daily Passenger Flow Significance - Daily passenger flow exceeding 10 million signifies a city's bustling activity, economic vitality, and supports sustainable infrastructure expansion [5][6]. - Among over 40 cities with operational subways/light rails, only 21 have daily passenger flows exceeding 1 million, and only 5 exceed 5 million [6]. Group 2: Comparison of Major Cities - Beijing and Shanghai lead in daily passenger flow, while Guangzhou and Shenzhen maintain around 9 million, with monthly passenger flows around 3 billion [11][12]. - In the second tier, only Chengdu exceeds 6 million, with significant gaps to other cities like Xi'an and Hangzhou, which exceed 4 million [15]. Group 3: Factors Influencing Passenger Flow - Passenger flow is closely linked to urban population density and economic activity; cities with higher urban population ratios tend to have higher subway ridership [19][23]. - Shenzhen's high passenger flow is attributed to its compact urban area and extensive subway network, which is densely populated and economically vibrant [26][31]. Group 4: Future Projections and Developments - Shenzhen's subway network is expected to expand significantly, potentially exceeding 800 kilometers by 2030, enhancing connectivity within the Greater Bay Area [37][39]. - The influx of population, including a substantial number of visitors from Hong Kong, contributes to the increasing passenger flow, creating a positive feedback loop for urban transit [40][41].