When looking at a nominatim sample response I am keen to key:value pairs like "category":"highway" and "type":"motorway". Seems like line 44 in geo.py would that be the place to add this, but would be already enough?

Of course the intended interpretation (stations close to high-traffic roads) of these results could be easily misleading; maybe a high traffic-road is just at the junction of two roads (or the sensor is behind a big building).