Classifying and zoning wind environments in metro station areas at the city scale: A case study of Nanjing

While the “3D” principles—density, diversity, and design—remain central to Transit-Oriented Development (TOD), their effectiveness in metro station areas is increasingly constrained by the complex interplay of natural and built environmental factors. Among these, wind conditions are critical yet often overlooked. This study proposes a zoning optimization framework based on a dual-dimensional model combining wind speed (aerodynamic force) and the Frontal Area Index (FAI, morphological resistance). Using WRF/CALMET simulations and GIS-based modeling, localized wind data were obtained for 146 metro stations in Nanjing. K-means clustering and spatial autocorrelation analyses identified four representative wind environment types. Key findings: the mean station wind speed is 3.08 m/s—pedestrian-comfortable yet slightly below the city mean—and the mean FAI is 1.01, indicating generally high aerodynamic resistance. About 50% of stations fall within FAI 0.79–1.21; higher FAIs cluster in historic cores, elevated values occur in both flat and hilly terrains via different mechanisms, and lower values appear near large open spaces. Clustering yields four wind-environment types from “low-speed–high-FAI” to “high-speed–low-FAI.” The resulting wind-zoning map provides a robust basis for differentiated zoning and climate-responsive TOD planning.