Isochrone

isochrone

[demo] [uptime]

Live: iso.huseyincapan.dev

Click anywhere on the map and see the street network you can actually reach on foot within 15 minutes — coloured by arrival time, with mobility profiles that account for stairs and unpaved paths.

OSM data → PostGIS + pgRouting → Express → Leaflet.

Why not a polygon?

Every isochrone map I could find answers with a filled polygon. That is wrong unless you are a pigeon: a polygon claims you can reach the middle of a block, cross a rail cutting, walk through a building. On the corner above, the same 15 minutes gives you 107.6 km of reachable streets; the hull drawn around them covers 3.28 km² and claims 30.4 km of street the walk cannot actually reach. This map draws the network.

How it works

pgr_drivingDistance walks the street graph from the vertex nearest your click until the time budget runs out, and returns every reachable edge with its arrival time. Those edges are grouped into 10 equal time bands and drawn directly.

Edge cost is length / speed in seconds, computed per request from the selected profile, so a profile is a few numbers rather than a schema change:

These factors are estimates, not measurements — see Known gaps.

Where should I live?

Answer a short questionnaire weighting seven everyday layers (dining, green space, playgrounds, groceries, health, kindergartens, schools) and the whole Berlin map re-ranks to show where your weighted 15-minute city actually is, as walk, bike or wheelchair.

The trick is that nothing is routed at question time: 21 full-city reachability surfaces (7 layers × 3 profiles, ~134,000 grid cells each) are precomputed offline, so re-ranking the city is one aggregate query. Stroller is deliberately absent here: its speed factors are uncalibrated estimates and must not be published as if measured.

Ask Claude about it (MCP)

The isochrone-mcp package lets any MCP client answer reachability questions against this API:

claude mcp add isochrone -- npx -y isochrone-mcp

One tool, reachable_area: origin + minutes + profile, optional target ("can I get there in time?"). Returns a prose summary and a map link, not coordinate soup. Details in mcp/.

Known gaps

• Graph islands. The vertex nearest a click can sit on a disconnected fragment — 52.515,13.400 reaches 13 nodes. Fix is a one-time pgr_connectedComponents table for the vertex lookup to join against.
• Calibration. The speeds above are guesses. Google's Isochrones API (Preview) supports WALK and returns GeoJSON, so the walk profile could be calibrated against it. It has no stroller/wheelchair mode, so those stay unvalidated.
• Stranded origins render as a tiny blob rather than saying "unreachable with this profile".

Running it yourself

Dev setup, deployment, city import and the ops notes live in docs/OPERATIONS.md.