Dataset for: An Areal Approach to Spatial Accessibility Analysis

Place-based spatial accessibility quantifies the distribution of access to goods and services across space. The Two-Step Floating Catchment Area (2SFCA) family of methods have become a default tool for spatial accessibility analysis in part due to the intuitive approach and interpretability. This family of methods relies on calculating catchment areas around supply locations to estimate the area and population that may utilize them. However, these `catchment areas' are generally defined by origin-destination matrices of travel-time, giving us point-to-point distances and not polygons with actual area. This means that population geographies (census tracts, blocks, etc.) are binarily included or excluded, with no room for partial inclusion.When using non-granular data, which is often the case due to data privacy restrictions, this has the potential to cause significant errors in accessibility measurements. In this paper, we propose Areal 2SFCA: a new approach that considers the area of overlap between travel-time polygons and population geographies. We apply the Areal 2SFCA method using a case study that compares the Enhanced Two-Step Floating Catchment Area (E2SFCA) and an Areal E2SFCA for the state of Illinois using multiple population granularities.