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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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