Equity-Oriented Public Transport Accessibility Analysis Using GTFS, Spatial Proximity, and Demographic Sensitivity

Promoting equitable and sustainable urban mobility requires accessibility assessment approaches that extend beyond purely geometric proximity measures toward service-sensitive and behavior-informed evaluation. This study develops an open-source GIS workflow that integrates General Transit Feed Specification (GTFS) datasets, demographic grid data, and spatial proximity modelling to construct three complementary accessibility-related indicators. Transit operational data are processed to derive service-strength indicators representing temporal service intensity at the stop level. Spatial proximity is evaluated through distance-based measurements between population grid centroids and the nearest public transport stops, subsequently transformed into a normalized proximity score reflecting perceived spatial effort. Demographic attributes, specifically age and gender structure, are also translated into a behavior potential index representing relative travel sensitivity across the urban grid. Then, rather than aggregating these components into a single composite accessibility indicator, the study analyses the spatial distribution of service strength (Sg), behavior potential (Bg), and proximity score (Pg) independently. Its empirical application to the metropolitan area of Valencia, Spain, reveals notable spatial disparities across these dimensions and highlights zones where demographic demand potential diverges from operational service provision. By relying exclusively on standardized open datasets and non-proprietary GIS tools, the proposed framework enhances methodological transparency, reproducibility, and transferability. The workflow provides a diagnostic foundation for future integrated accessibility modelling while preserving interpretative clarity at the indicator level.