Urban Accessibility and Collaborative Representation: A Comparative Analysis of OpenStreetMap Data in Milan, Rome and Naples

Urban accessibility for people with disabilities is a central aspect of inclusion policies and quality of life, extending beyond technical requirements to encompass spatial justice and the right to the city (Imrie & Kumar, 1998; Soja, 2010). This study adopts a rights-based urbanism framework, positing that gaps in collaborative mapping may reflect broader patterns of informational inequality rather than solely physical inaccessibility. Collaborative platforms such as OpenStreetMap (OSM) — a form of volunteered geographic information (Goodchild, 2007) — offer opportunities to study urban accessibility but raise concerns about completeness, quality, and spatial distribution (Haklay, 2010). Focusing on Milan, Rome, and Naples, the study examines OSM tags relevant to wheelchair accessibility (wheelchair, kerb, incline, sidewalk). A dual model is proposed: (1) a morpho-spatial accessibility index, measuring potential accessibility based on mapped features, and (2) an informational coverage indicator, assessing the spatial distribution and completeness of accessibility data. Spatial statistical methods are applied to identify gaps, clustering, and patterns of data production, allowing differentiation between physical accessibility and its digital visibility. Results reveal extremely limited and uneven coverage, indicating that missing data reflect mapping gaps rather than actual inaccessibility. The comparative analysis suggests that these patterns are not only local but may indicate structural issues in collaborative data production. Theoretical implications highlight the link between spatial justice and digital information, framing accessibility as both a physical and informational right. Practical implications stress the need to integrate collaborative and institutional data to produce reliable accessibility maps, guiding policymakers in prioritizing interventions and supporting inclusive, evidence-based urban planning. In conclusion, while OSM provides a valuable knowledge base, its limitations underscore the importance of combining bottom-up and institutional sources to enhance reliability and equity, ensuring that urban accessibility reflects both real and digitally visible conditions.