Day 13 · Interactions — When three lifelines meet

Data

BD Hospital Dataset (hospitals, clinics, pharmacies), fire stations, garment factories, economic zones and major roads from the GIS Data folder; BBS Population and Housing Census 2022 thana populations; city-corporation boundaries. The registry is incomplete and urban-biased; population per 250 m cell is a dasymetric model; distances are straight lines in UTM 46N.

Methods

1. Study areas: the two Dhaka city corporations (DNCC + DSCC, 53 thana polygons, 10,250,630 people) and Chattogram City Corporation (15 thanas, 3,273,329 people), BBS Population and Housing Census 2022. White gaps on the maps are outside the corporations (cantonment, airport, water).
2. Health facilities: the BD Hospital Dataset in the GIS Data folder, split into hospitals, clinics and pharmacies from the type and name keywords; pharmacies within 25 m of each other merged; an ‘emergency / 24 h’ flag from the name and type. Dhaka: 475 hospitals, 507 clinics, 2,049 pharmacies, 44 fire stations. Chattogram: 160, 51, 405 and 24.
3. Where people live: the census gives thana totals only, so each thana total is spread over a 250 m grid in proportion to a Gaussian kernel (σ = 400 m) of settlement proxies — mobile-phone towers, mosques, schools, health points, pharmacies, hospitals — plus a small floor. Cell sums equal the census total exactly (checked).
4. Every 250 m cell gets three distances (nearest hospital, pharmacy, fire station). For a chosen reach R each cell has a 3-bit code (H = 1, P = 2, F = 4); the eight codes are the eight combinations in the legend.
5. Shares are people-weighted; the web map recomputes the codes, the eight shares, the thana ranking and the colours for any R from 250 m to 3 km, and for any subset of the three services.
6. Thana coverage = people with every selected service within R ÷ people in the thana (cells carry a thana id). Tables show the five worst and best thanas with more than 20,000 residents.