Geospatial assessment of primary healthcare centres in Jeddah, Saudi Arabia

Rapid urban growth has increased concerns about spatial equity in access to Primary Healthcare Facilities (PHCs), particularly in contexts where proximity-based assessments may overestimate effective access by overlooking population demand and service capacity. This study evaluates district-level accessibility and equity of PHCs in Jeddah, Saudi Arabia using a capacity-sensitive Modified Two-Step Floating Catchment Area (M2SFCA) framework incorporating population weighting, distance decay and bed capacity. Network-based service area analysis was used to define catchment thresholds, while origin-destination cost matrices supported accessibility indexing. Spatial patterns were examined using Global Moran's I, and distributional equity was assessed through coefficient of variation, percentile ratio, accessibility shares, Gini coefficient and Lorenz curves. A planning-oriented location-allocation model evaluated a scenario-based PHC expansion. Results show that although approximately 69% of the urban area lies within nominal PHC catchments, baseline accessibility exhibits noticeable spatial inequities, with near-zero access in several peripheral districts and significant spatial clustering (Moran's I = 0.398). The proposed scenario introducing four PHCs with varied capacity produced systematic improvements in underserved areas. The percentage ratio declined sharply from 81.34 to 9.13, demonstrating substantial disparities between the highest and lowest-access districts. This increased the accessibility share of the bottom 40% of the population, and lowered overall inequality from 0.191 to 0.172 while slightly weakening spatial clustering. The findings demonstrate that capacity-aware accessibility modelling integrated with planning scenarios provides policy-relevant insights for improving spatial equity in PHC provision and is transferable to other rapidly urbanizing urban contexts.