Multiple dimension equity assessment of walking for visual and physical access to central parks across 27 Yangtze River Delta cities

The Yangtze River Delta (YRD), as a globally significant megacity region, faces intense land constraints and growing demands for equitable access to high-quality urban parks. However, traditional planning often prioritizes physical proximity while overlooking the sensory experience, leading to a disconnect between where residents can "reach" and what they can "see." To bridge this gap, this study develops an integrated framework that couples pedestrian potential with visual perception. By integrating GIS-based pedestrian network analysis and FCN-driven semantic segmentation of street-view image, we evaluated the central parks of 27 cities across the YRD. The results demonstrate that: (1) Urban scale is closely linked to service equity, with 37% of cities exhibiting a distinct accessibility disadvantage relative to the regional average. (2) Large cities tend to dominate in green perception (GVI), whereas small and medium-sized cities are characterized by stronger blue perception (BVI). (3) A significant spatial divergence exists between physical walkability and blue-green perception, manifesting into four distinct spatial typologies at the urban scale. (4) Areas theoretically expected to have high accessibility and perception-such as waterfronts or park edges-underperform in reality. These findings suggest that theoretical attractiveness does not naturally translate into functional accessibility without intentional street-level integration. Achieving park equity requires a dual focus on both sensory experience and physical access. Consequently, this study proposes a targeted urban renewal framework to assist managers in implementing type-specific micro-interventions, providing a scalable model for achieving sensory-physical synergy in land-constrained megacity regions.