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Cover image for GeoJSON Traffic Events API with BBox and Radius Queries
Roman Kotenko
Roman Kotenko

Posted on • Originally published at road511.com

GeoJSON Traffic Events API with BBox and Radius Queries

#api #javascript #webdev #geojson

If you're building a traffic map, the last thing you want is to parse a proprietary format and convert coordinates. Road511's GeoJSON endpoints return standard FeatureCollections that drop directly into Leaflet, Mapbox, MapLibre, ArcGIS, QGIS, or any GeoJSON-compatible tool.

GeoJSON Endpoints

Every list endpoint in Road511 has a /geojson variant:

GET /api/v1/events/geojson
GET /api/v1/features/geojson?type=cameras
GET /api/v1/truck/corridor/geojson
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All return Content-Type: application/geo+json with a standard FeatureCollection.

Bounding Box Query

Show events in the current map viewport:

const bounds = map.getBounds();
const bbox = [
  bounds.getWest(), bounds.getSouth(),
  bounds.getEast(), bounds.getNorth()
].join(',');

const res = await fetch(
  `https://api.road511.com/api/v1/events/geojson?bbox=${bbox}&status=active`,
  { headers: { 'X-API-Key': key } }
);
const geojson = await res.json();
L.geoJSON(geojson).addTo(map);
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Radius Search

Find everything within 50km of a point:

curl "https://api.road511.com/api/v1/events/geojson?lat=34.05&lng=-118.24&radius_km=50&status=active" \
  -H "X-API-Key: your_key"
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Multiple Feature Types

Build a layered map with different feature types:

const types = ['cameras', 'signs', 'weather_stations', 'rest_areas'];

for (const type of types) {
  const res = await fetch(
    `https://api.road511.com/api/v1/features/geojson?type=${type}&jurisdiction=CA`,
    { headers: { 'X-API-Key': key } }
  );
  const geojson = await res.json();
  L.geoJSON(geojson, {
    pointToLayer: (f, latlng) => L.marker(latlng, { icon: icons[type] })
  }).addTo(layerGroups[type]);
}
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LineString Geometry

Not everything is a point. Construction events, truck routes, and weight restrictions include polyline geometry:

{
  "type": "Feature",
  "geometry": {
    "type": "LineString",
    "coordinates": [[-87.63, 41.88], [-87.62, 41.89], [-87.60, 41.90]]
  },
  "properties": {
    "id": "fhwa-il-staa-001",
    "feature_type": "truck_routes",
    "name": "I-90 STAA National Network"
  }
}
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Spatial Queries Under the Hood

Road511 uses PostGIS for all spatial operations. Every feature has a geometry column with a spatial index. Bounding box queries use ST_Intersects, radius queries use ST_DWithin on geography. The truck corridor endpoint builds a buffer geometry with ST_Buffer and intersects it against all truck-related features.

Try It

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