Exploring the nonlinear effects of greenery on active travel among the ageing population

This paper examines the nonlinear influences of the quantity and quality of street-level greenery on active travel among older adults. The active travel information was obtained from the Study on Global Ageing and Adult Health conducted in Shanghai, China. Street-level greenery was assessed based on street view data and a deep learning approach, namely street view greenery quantity (SVG-quantity) and quality (SVG-quality). Gradient boosting decision tree models and SHapley Additive exPlanations were applied. The results showed that SVG-quantity had a positive and nonlinear link with active travel. However, SVG-quality was positively correlated to the propensity for active travel, but the association became inverse when SVG-quality exceeded a specific cut-off point. SVG-quality also had a nonlinear and positive association with the duration of active travel. This research demonstrates the importance of improving the provision of street-level greenery in urban areas, which is crucial for facilitating active lifestyles among the ageing population.