Spatial Accessibility
2023-7-27
Multi-Mode Huff-Based 2SFCA: Examining Geographical Accessibility to Food Outlets in Austin, Texas
This paper examines limitations in current methods for measuring spatial accessibility to healthcare and proposes a new approach to account for suboptimal configurations of facilities.
Abstract:
The retail food environment draws much attention from scholars because it can shape individuals’ eating behaviors and health outcomes. Although much progress has been made, current retail food environment assessments mainly use simple food accessibility measures while overlooking the role of multiple transportation modes. This research proposed a multiple-mode Huff-based Two-step Floating Catchment Area (2SFCA) method to measure geographical access to food outlets in Austin, Texas. The spatial accessibility score was calculated with low to high impedance coefficients. Our analyses revealed an urban core-and-peripheral disparity in spatial accessibility to food outlets. We also compared the proposed multiple-mode Huff-based 2SFCA with its single-mode counterpart using t-test and relative difference methods. The comparison illustrates that the difference between the two methods of calculating healthy and unhealthy food accessibility is significant when the impedance coefficient is set to be 1.4 and 1.5, respectively. Our proposed multi-mode Huff-based 2SFCA method accounts for the various transport means and the spatial heterogeneity in population demand for food services; this could support developing intervention strategies to target under-served healthy food areas and over-served unhealthy food areas.
Summary:
- The study proposes a new multi-mode Huff-based Two-Step Floating Catchment Area (2SFCA) method to measure geographical accessibility to food outlets in Austin, Texas.
- The new method accounts for multiple transportation modes (driving, public transit, walking) and spatial heterogeneity in population demand. This overcomes limitations of prior 2SFCA methods.
- The method was applied to measure access to healthy (supermarkets, grocery stores) and unhealthy (convenience stores, fast food) food outlets in Austin.
- Results showed a core-peripheral disparity in food accessibility, with higher access in urban core and lower access in peripheral areas.
- As impedance increased, spatial accessibility diverged more, exacerbating disparities.
- The multi-mode method resulted in lower estimates of accessibility in urban core areas compared to single-mode method, reducing overestimation.
- In peripheral areas, multi-mode estimates were higher than single-mode, correcting underestimation.
- Multi-mode method showed significant differences from single-mode method at impedance coefficients of 1.4 (healthy food) and 1.5 (unhealthy food).
- Study demonstrates importance of accounting for multiple transport modes and population heterogeneity in food accessibility measurement.
Study questions and answers:
| Study Question | Finding |
|---|---|
| How does geographical accessibility to food outlets vary across Austin? | Accessibility highest in urban core, lower in peripheral areas |
| How does multi-mode Huff-based 2SFCA method compare to single-mode method? | Multi-mode results in lower estimates in urban core, reducing overestimation. Higher estimates in periphery, correcting underestimation. |
| Is there a significant difference between multi-mode and single-mode methods? | Yes, significant difference at impedance coefficients of 1.4 (healthy food) and 1.5 (unhealthy food) |
| How does impedance coefficient impact spatial accessibility estimates and disparities? | As impedance increases, spatial accessibility diverges more, exacerbating disparities |
| What is the importance of accounting for multiple transport modes? | More accurate measurement of food accessibility, especially for disadvantaged groups relying on non-auto modes |
DOI: 10.3390/ijgi11110579