Lost in Yamanote!

Question: inside the Yamanote loop, where is the point farthest from any train or subway station? This is a city-scale "pole of inaccessibility" problem.

The Yamanote Line encloses the core of Tokyo, so this is a fun way to measure transit convenience in one number: the worst-case walking distance to a station.

Initial LLM guess: likely Ueno Park or Shinjuku Gyoen, roughly 1.5-2.5 km from the nearest station.
The actual measured answer is much shorter.

Result: Yamanote Pole of Inaccessibility

Location ("ダンポロ") 35°39'22.4"N 139°42'46.7"E

Nearest-Station Distance ~947 meters (about a 15-minute walk)

Administrative Area Shibuya-ku

Practical Note There is bus coverage nearby, so this is not transit-isolated in practice.

Interpretation: within the Yamanote boundary, the worst-case direct walk to rail transit is roughly 950 meters.

Photo at Danpolo point — Picture at ダンポロ.

Distance Map

Map points are color-coded by distance from the nearest station.

Green: ≥ 500 m
Yellow: ≥ 600 m
Light Orange: ≥ 700 m
Dark Orange: ≥ 800 m
Red: ≥ 900 m

How It Was Computed

I pulled station coordinates from OpenStreetMap via Overpass Turbo using a bounding box around the Yamanote area. That yielded about 124 stations inside the loop.

Station Query (Overpass)

[out:csv(name, ::lat, ::lon; false; ",")]
[timeout:60][bbox:35.611534, 139.690819, 35.745955, 139.789352];
(
  node[railway=station];
  node[station=subway];
);
out body;

Two Approaches

Python method: compute nearest-station distance over sampled coordinates and rank by distance (see distance.py).
Overpass method: directly query features at least ~940 m away from all stations in the bounding region.

Overpass Distance Filter

[out:json][timeout:60][bbox:35.611534, 139.690819, 35.745955, 139.789352];
(
  node[railway=station];
  node[station=subway];
)->.stations;
nwr->.buildings;
nwr(around.stations:940)->.near_buildings;
(.buildings; - .near_buildings;);
out geom meta;

The two approaches converged on the same answer region.