Find the homes public transport doesn't reach
Transport planners measure how many homes sit beyond easy reach of a stop. This example finds every residential building in Singapore more than 400 m in a straight line from a bus stop, from OpenStreetMap.
Singapore homes more than 400 m from a bus stop
Data: OpenStreetMap bus stops and residential buildings
Method: keep residential buildings with no bus stop within 400 m, measured on the ellipsoid
-- Residential buildings with no bus stop within 400 m
WITH stops AS (
SELECT geom FROM osm.public_transport_point
WHERE osm_type = 'bus'
AND geom && ST_MakeEnvelope(103.58, 1.20, 104.07, 1.49, 4326)
)
SELECT b.osm_id, b.osm_subtype AS building, b.geom
FROM osm.building_polygon AS b
WHERE b.osm_type = 'building'
AND b.osm_subtype IN ('apartments', 'residential', 'house', 'semidetached_house', 'terrace', 'detached', 'dormitory')
AND b.geom && ST_MakeEnvelope(103.6, 1.22, 104.05, 1.47, 4326)
AND NOT EXISTS (
SELECT 1 FROM stops AS s
WHERE s.geom && ST_Expand(b.geom, 0.005)
AND ST_DWithin(b.geom::geography, s.geom::geography, 400)
);Run it on your data
Upload your own stops, or the stops of a planned route, as a file or spreadsheet and swap them in for the stops step to see which homes they leave out. Change 400 to test another distance. See supported files.
Frequently asked questions
Is 400 m a walking distance?
No. It is straight-line. Walking routes need a road network and a different method.
Why count buildings rather than people?
OpenStreetMap maps buildings, not residents. The count shows where the gaps are, not how many people they affect.