Integrating functional accessibility and pedestrian environmental comfort: A spatially explicit framework for urban walkability evaluation

Urban walkability is central to sustainable urban development and, at the city scale, is increasingly viewed as shaped by both functional accessibility and pedestrian environmental comfort (PEC). However, most citywide assessments remain predominantly function-oriented, and few provide explicit behavioral validation using observed walking patterns. This study addresses this gap by proposing a spatially explicit, dual-dimensional framework that treats functional accessibility and PEC as co-equal components of walkability. Using Nantes, France, as a case study, we implement the framework on a uniform 150 m × 150 m grid and derive three composite indices—Traditional Walkability Score (TWS), a PEC index, and a PEC-enhanced Walkability Score (PEWS)—from GIS indicators standardized and combined using entropy-based weighting. Our analysis reveals a systematic spatial mismatch between functional and environmental dimensions: TWS concentrates in amenity-rich and well-connected areas, whereas PEC is highest along blue–green corridors. The integrated PEWS induces a targeted spatial re-ranking, deprioritizing functionally rich but environmentally harsh central areas while upgrading nature-rich peripheral zones. We then behaviorally validate the framework using observed pedestrian counts and gridded resident population data from INSEE, operationalized as a deviation metric comparing observed flows with population-based expectations. Blue–green features (trees, rivers, and green spaces) are associated with higher-than-expected pedestrian activity, whereas proximity to major motorized roads is associated with lower-than-expected activity. These findings support PEC as a necessary component of city-scale walkability assessment and provide actionable guidance for planning interventions.