Originally Posted by
njkayaker
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I wonder what data they are using and whether they use OSM with the OSM maps.
Good question. I've only seen one online map data base that does an OK job at showing you what road is gravel/dirt and what's asphalt and that is Gaia GPS. Even there you need to consult the legend to verify road surface as they let you download a lot of different maps, Gaia Topo, USGS Topo, Nat'l Geo, etc... Gravel Maps does some good stuff, but it functions like TrailForks in that a road surface would be indicated as gravel IF somebody road and tracked a ride, then uploaded or traced a route.