Nonlinear effects and heterogeneous preferences: Impact of built environment on vitality of Shanghai’s pedestrian commercial streets

In high-density urban areas, pedestrian commercial streets are essential for urban vitality and experiential economy, but research on heterogeneous impacts f built environment factors across user groups and comparisons between functionally distinct streets remains insufficient. This study investigates two representative commercial streets in Shanghai— Taikoo Li Qiantan (business consumption-oriented) and Panlong Tiandi Qingpu (historical and cultural-oriented)—using a mixed-method approach combining questionnaires, Wi-Fi trajectory data, field surveys, and machine learning (XGBoost) to analyze six key built environment factors:anchor store intensity (SI), street width (ST), green view ratio (GVR), billboard density (BD), store interface transparency (FT), and the number of tables and chairs (TAS).The key findings include the following:(1) Core built environment factors exhibit significant nonlinear effects. SI shows a “marginal decreasing effect” (SHAP range: 0.2–0.4 at medium and low intensity, growth slows when brand coverage ≥ 70%). GVR demonstrates a “threshold effect” (negative SHAP value when GVR < 10%, positive when GVR > 15%). BD shows an “age-sensitive saturation effect” (continuous positive correlation for ages 18–35, plateauing for those ≥ 56 when BD > 60%). (2) Heterogeneous preferences: men prioritize SI (0.25–0.4) and FT (0.1–0.25), while women focus on BD (0.2–0.35). Younger groups (18–35 years) prioritize BD (importance > 0.4), middle-aged (36–55 years) balance SI, FT, and TAS, while the elderly (≥56 years) focus on TAS (0.25–0.4) and GVR. (3) This study reveals the synergistic matching mechanism between different population characteristics and street vitality, and pedestrian commercial streets of different business model types have formed differentiated vitality perception models with specific population characteristics. By conducting quantitative analysis of the nonlinear effects of built environment factors and the laws of population heterogeneity, this study provides a scientific basis for the precision positioning and differentiated design of commercial streets, promoting the transformation of urban planning from the traditional standardized model to people-oriented customized design.