OpenNames-to-GeoJSON

Ordnance Survey (OS) OpenNames is a comprehensive dataset of place names, roads numbers and postcodes for Great Britain; you can read more about it here. It's a free OGL dataset provided as either a CSV or GeoPackage in the EPSG:27700 (British National Grid) CRS.

This repo hosts a homemade utility script for JS/Deno which converts the CSV format of this dataset into a single (and fairly large) GeoJSON FeatureCollection. It was originally written to assist the ETL process into MongoDB, but can be customised for other use cases. In summary, the script will:

• Stream in each CSV file.
• Create a new feature for each dataset entity.
• Copy a subset of the original metadata into each feature's properties.
• Convert the geometry of each feature to WGS84 using the Proj4JS library.
• Store the output as output.geojson in the working directory.

Running the Script

This script runs on the Deno runtime. In the same directory as the script, run:

deno run index.ts "/path/to/opennames/Data"

Where the /Data directory is equivalent to the parent directory of the CSV files on your filesystem. This script will take a few seconds to run; don't open the output.geojson file until the script has completed.

Output Feature Schema

The CRS conversion process utilises a Helmert datum transformation which can lead to inaccuracies of up to 3.5m in some areas. Given the nature and purpose of OS OpenNames I have determined this to be an acceptable range of error, but please keep this in mind depending on your use case!

The GeoJSON FeatureCollection will contain point features with the following attribution:

{
  "type": "Feature",
  "properties": {
    "fid": "osgb4000000073495356", // OS Identifier
    "name": "Durham University", // Name1
    "class": "other.higheroruniversityeducation", // Type & LocalType
    "source": "Ordnance Survey OpenNames",
    "gridRef": "NZ24" // OS Grid Ref (via filename)
  },
  "geometry": {
    "type": "Point",
    "coordinates": [-1.5611190052871562, 54.772369280517154]
  }
}

License

This script is MIT licensed. Feel free to modify it to suit your needs.