Transit fares and space-time accessibility: measuring inequalities in park accessibility for São Paulo favela residents using mobile phone and smart card data

This paper examines the role of transit fares and socio-demographic factors in shaping accessibility inequity, utilizing big data sources, including call detail records (CDR) and smart card data (SCD). Unlike prior studies, which often overlook financial constraints or rely on small-scale surveys, we develop a space-time measure that integrates fare costs and leverages large-scale mobility data to capture individualized accessibility. Applying this framework to park access in São Paulo, we reveal stark inequities: up to 72.5 % of favela dwellers cannot access parks within their available time and budget, with marginalized communities facing the highest barriers under tighter budget constraints. The findings underscore that affordability has a significant influence on accessibility, with wealthier populations enjoying disproportionately higher access levels. These results demonstrate the potential of integrating CDR and SCD into space-time accessibility analyses, offering a nuanced understanding of the complex interplay between transit affordability and spatial equity.