In the event of tagging some highways that are narrow enough to deny motorcar (maybe also motocycles) access but without any declared access rights, which is the preferred method to follow?
I mean the typical alleys of medieval villages. Should I tag them as residential, living_street, pedestrian, alley ?
I am inclined to use living_street with motorcar=no but I am unwilling to use any access tag if there is no sign denying/allowing access rights to some transportation method.
Conventions vary from one place to another about what highway tag value should be applied to local conditions. So, if there is a local mapping group they might have come up with a convention for your situation.
If there is no local convention, then keep in mind that highway=* tagging conflates physical description and use which probably would be frowned upon for new tags. Basically if you use residential or living street or whatever you are effectively setting default assumptions for other things (minimum number of lanes, maxspeed, etc.) than you care about.
So you might want to side step that a bit an use highway=unclassified just to show it is a travelled way and then add tags that describe the physical situation. Probably surface=, and width= would be good tags to start with. If your width is, say 1.5 meters, it would imply that motorcar could not use it even though there is no law against trying.
If its too narrow for motorcars, its probably a path (or footway/cycleway). When using the path value, you should preferably add other information such as surface and width, because path is a very generic value that does not imply much except that it’s not for motorcars.
highway=unclassified does not mean “unspecified” or “unknown”, despite the misleading name. It refers to non-residential roads below the tertiary classification. This might be roads in an industrial area, or between villages if it’s not important enough to be tertiary.
Ok, I aggree to use path. What I found is that many paths in medieval town centres (like the one I linked above) are already tagged as residential ways. That sounds to me as a so called local convention based on an initial misunderstanding on the use of the appropriate highway tag: “path” seems to be used only on rural or natural areas, whereas ways with proper names between houses in town centres are considered residential despite their different right of ways or physical nature.