I'm not sure you can use that to reliably distinguish between what in OSM would be called a track or a service road.  Compare https://map.atownsend.org.uk/maps/map/map.html#16/58.9754/-3.3498/2 and https://map.atownsend.org.uk/maps/map/map.html#16/58.9754/-3.3498/6 , 