Data-Innovation-For-Africa/distance-healthcare-accessibility
Domain:
geospatialhealthcareRecord type:
project
Creator:
Dat
Host:
Distance - measuring geographic accessibility to healthcare across Africa (AfDB Data Innovation Lab). Kigali, Rwanda use case.
# Distance — How Long Is a Mile?
**Measuring geographic accessibility to healthcare across Africa.**
A **Data Innovation for Africa** initiative of the **African Development Bank (AfDB)**.
A straight line on a map says almost nothing about whether a patient can *actually reach a doctor*. This project reframes healthcare accessibility around **travel time and real service availability** rather than as-the-crow-flies distance, and computes a reproducible **accessibility indicator** to help target investment where it closes the widest gaps — so that no one is left behind.
👉 **Live page:** open `index.html` (a self-contained page — no build step, no dependencies).
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## The two approaches
The project measures accessibility along two complementary axes:
| | **Distance Approach** | **Gravity Model** |
|---|---|---|
| **Question** | How far — in time — is the nearest facility? | Given demand and friction, is the service *enough*? |
| **Tools** | Distance Matrix · O–D Matrix · Isochrone Zones | Provider-to-population ratio · **2SFCA** · friction weighting |
| **Measures** | Proximity (supply-side, geographic) | Availability (supply **and** demand) |
The Distance Approach produces the travel times *dᵢⱼ* that feed the Gravity Model. One says *"how far"*; the other says *"with what real level of service."*
## The 2SFCA algorithm
**Two-Step Floating Catchment Area** (Luo & Wang, 2003 [1]):
- **Step 1 — Facility supply ratio:** `Rⱼ = Sⱼ / Σ Pₖ`
For each facility *j*, gather all population *k* within travel time *d₀* and divide its physicians *Sⱼ* by that catchment population.
- **Step 2 — Accessibility at a residence:** `Aᵢ = Σ Rⱼ`
For each location *i*, sum the supply ratios of every facility *j* reachable within *d₀*. Higher *Aᵢ* = better access.
Method family: 2SFCA [1], E2SFCA [4], 3SFCA [5], M2SFCA [6], CB2SFCA [7].
## Methodology pipeline
1. **Prepare the layers** — population & facility points → centroids on a grid (QGIS, OSM, Overpass)
2. **Build the matri …