Multi-modal Two-Step Floating Catchment Area Analysis of Primary Health Care Accessibility

Variations of the two-step floating catchment area (2SFCA) technique are popular for measuring potential geographical accessibility to health care services. This paper proposes methodological enhancements to increase the sophistication of the technique by incorporating both public and private transport modes. This is achieved using dedicated network datasets to better reflect the travelling opportunities afforded by each mode. It is shown that the catchments upon which 2SFCA methodologies rely can vary significantly at any given location when alternative travel modes are accurately portrayed. The proposed model reports separate accessibility scores for each modal group at every demand point to better reflect the availability of service experienced by each particular cohort. An empirical study estimating potential accessibility to primary health care facilities in South Wales, UK is used to illustrate the approach. The outcome suggests the bus-riding cohort of each census tract may experience much lower accessibility levels than are estimated by an undifferentiated (car-only) 2SFCA model. Furthermore, accessibility levels for car-drivers are also misrepresented by an undifferentiated model. They profit from the lower demand placed upon service provision points by bus-riders and thus experience greater levels of accessibility than a car-only 2SFCA score might suggest.