Is your feature request related to a problem? Please describe.
When hiking or in rural areas, roads may not be suitable for everyone. Attached is an example screenshot from OsmAnd showing route details with very bad smoothness that is not clear from viewing the map. Some people may like to avoid those.
Describe the solution you would like
Define a set of "accessible" surface and smoothness values that are considered passable for casual hikers or bikers. Like avoid rocks in general or gravel below a certain smoothness.
Either warn or even better also increase the cost while routing. Warning might still be needed if there is no other way possible or distance difference to shortest (but non-accesible) route is too large.
Describe alternatives you have considered
Use Komoot or OsmAnd (see screenshot above)
Additional context
Hiking and outdoor sports like trail running.
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