Transportationer — 15-Minute City Analyzer

A web application for analyzing urban accessibility through the lens of the 15-minute city concept. Shows a heatmap indicating distance to locations of interest across 5 categories: Service & Trade, Transport, Work & School, Culture & Community, and Recreation.

Architecture

Browser (Next.js / React)
  ├── MapLibre GL JS (map + canvas heatmap)
  └── API calls → Next.js API routes

Next.js App Server
  ├── Public API: /api/cities /api/pois /api/grid /api/stats /api/isochrones
  ├── Admin API: /api/admin/** (auth-protected)
  ├── PostgreSQL + PostGIS (POI data, grid scores, isochrone cache)
  └── Valkey (API response cache, sessions, BullMQ queue)

BullMQ Worker (separate process)
  ├── download-pbf   → streams OSM data from Geofabrik
  ├── extract-pois   → osmium-tool + osm2pgsql → PostGIS
  ├── generate-grid  → PostGIS SQL (200m grid)
  ├── compute-scores → KNN lateral join + sigmoid scoring
  └── build-valhalla → Valhalla routing tile build

Valhalla → local routing (isochrones)
Protomaps → self-hosted map tiles (PMTiles)

Quick Start

1. Configure environment

cp .env.example .env
# Edit .env with strong passwords

# Generate admin password hash
node -e "require('bcryptjs').hash('yourpassword', 12).then(console.log)"
# Paste result as ADMIN_PASSWORD_HASH in .env

2. Start services

docker compose up -d

3. Add a city

Open http://localhost:3000/admin, log in, click Add City, browse Geofabrik regions (e.g. europe/germany/berlin), and start ingestion. Progress is shown live.

Processing time:

• Small city (< 100k pop): ~5–15 minutes
• Large city (1M+ pop): ~30–90 minutes

4. Explore

Open http://localhost:3000 and select your city.

Map Tiles

By default the app uses CartoDB Positron (CDN). For fully offline operation, download a PMTiles file for your region:

# Example: download Berlin region tiles
wget https://maps.protomaps.com/builds/berlin.pmtiles -O apps/web/public/tiles/region.pmtiles
# Then switch to the PMTiles style:
cp apps/web/public/tiles/style.pmtiles.json apps/web/public/tiles/style.json

Development

npm install
npm run dev               # Next.js dev server on :3000
npm run worker:dev        # BullMQ worker with hot reload

Required local services: PostgreSQL+PostGIS, Valkey. Easiest via:

docker compose up postgres valkey -d

Category Definitions

Category	OSM Sources	Default Threshold
Service & Trade	shops, restaurants, pharmacies, banks	10 min
Transport	bus stops, metro, train, bike share	8 min
Work & School	offices, schools, universities	20 min
Culture & Community	libraries, hospitals, museums, community centers	15 min
Recreation	parks, sports, gyms, green spaces	10 min

Scoring

For each grid point (200m spacing), the nearest POI in each category is found using a PostGIS KNN lateral join. The Euclidean distance is converted to travel time using mode speed assumptions (walking 5 km/h, cycling 15 km/h, driving 40 km/h). A sigmoid function converts travel time to a score in [0,1]:

score = 1 / (1 + exp(k * (travel_time - threshold)))

Where k = 4/threshold, giving score=0.5 exactly at the threshold.

The composite score is a weighted average of all 5 category scores, with user-adjustable weights.