I calculated this “longest road” from #OpenStreetMap @geofabrik Europe extract.
I define “a road” here as a continuous sequence of OSM ways with a `highway` tag & the same `name` tag. `osm-lump-ways` generates this with one simple command:
osm-lump-ways -i europe-latest.osm.pbf -o euro-roads.geojson -f highway -f name -g name --split-into-single-paths --min-length-m 10000 --split-into-single-paths-by crow_flies