Radius — Berlin Train + Bike

Plan combined train + bike tours starting from Berlin.

Live: radius.kettner.berlin

Instead of cycling loops out and back every time, Radius helps you find rides that start at a train station outside the city so you can cycle home. You set your home location, a target cycling distance, and a route profile — the app finds train connections to the stations that put you the right distance away, then routes you back.

How it works

1. Pick your home location on the map (defaults to Alexanderplatz).
2. Set your desired cycling distance and route preferences.
3. Radius finds regional/S-Bahn stations roughly that distance away, looks up live train connections, and draws bike routes back home.
4. Export any route as GPX for your bike computer.

Tech

• Vanilla JS + Vite
• Leaflet + MapLibre GL for the map
• Bike routing, elevation, and GPX tracks via BRouter
• Line routes, stations, and geometry from the VBB transit API, which also powers the live train connections. Sourcing from VBB keeps the map in step with the live timetable (construction reroutes, line renumberings) instead of lagging behind OpenStreetMap.

Development

npm install
npm run dev      # start the dev server at http://localhost:5173
npm run build    # build to dist/
npm run preview  # preview the production build

Data

npm run fetch-data   # fetch fresh station/line geometry (data/fetch-stations.js)

Station data lives in data/ (lines.json, station_mappings.json). It is refreshed automatically every day at 03:00 UTC by the Update Station Data workflow, which rebuilds the line/station data from the VBB API and commits any changes. (station_mappings.json is now an identity map — stations carry their VBB stop ID natively — kept for the frontend's existing lookup.)

The build cross-checks itself against the German Wikipedia list of Berlin-Brandenburg rail lines: lines that the page lists but the VBB hubs didn't surface are self-healed by harvesting their route's termini, and out-of-state lines caught at border hubs are filtered out. The leftovers (missing / filtered) are written to data/qa-report.json for review — "missing" lines are usually construction-suspended, and the VBB API stays the source of truth for what's actually running.

Train lines are drawn in two muted overlay colors (S-Bahn green, all other trains blue) to stay readable once bike routes are layered on top.

Deployment

Pushes to main (and successful data-update runs) trigger the Deploy to GitHub Pages workflow, which builds and publishes dist/ to GitHub Pages.

Project layout

src/
  app.js            # main controller: geolocation, map, search, results
  algorithm/        # station finding, route service, GPX export
  ui/               # map renderer, controls, route list, mobile sheet
  styles/
data/               # station/line data + VBB fetch script
.github/workflows/  # deploy + daily data update