We can’t and this has already been discussed many times why in this forum. The refs are the best we have.
Anything else, including relative importance to nearby classifications, is too subjective and the reason for edit wars.
I agree the current guidelines are confusing, but I also think any (simple or complex) exception will be ignored by most mappers.
The question is why do we need exceptions in the first place?
Why can we not rely on this simple schema for major highway classification?
Are there any important live OSM use cases out there that require more complex rules/exceptions?
Are there really any large numbers of users in Thailand relying on OSM highway classifications for routing ? (instead of Google, Garmin…)
If not, we may be making things complicated for no good reason…
Because, while the ref is the best we have, it is not good enough. According to the OSM highway wiki, "highway= distinguishes roads by function and importance rather by their physical characteristic and legal classification."* Although the legal classification is used in many countries, it is common that it is used together with additional detail or exception to better represent importance. The correlation with other countries’ tagging could be one reason for this.
There may not be a large number of people using this, but I believe it would be better if we could do it better. As I’ve seen, the most common use case of OSM may not be routing, but rather using it as a base map or for some kind of data visualization. (for example, for people to see it as a whole country)
Another reason I’m trying to do this is to clean up inconsistencies for major highway tagging (situation in the Southern VS Northern, for example), which I have the capability to handle on my own (and it’s all already mapped, so edit wars shouldn’t be a huge problem), by not changing too many of them. The difficulty is that, due to current guidelines, I can’t tell which one is incorrectly tagged, so I can’t make my own decision because I have to obey the prior mapper’s decision. That is why I propose replacing “Most, but not all” with something more unambiguous about what it means. I believe this will put an end to or reduce major highway disputes, at least until a new road is built.
Right now the wiki table is confusing, depending on the screen size it’s not clear which classification row matches with the ref style cell.
B) adding some extra tags to inform mappers about wiki and exceptions (and deter them from changing them)
source:highway=WikiProject_Thailand
note:highway=upgraded/downgraded from xxxxxxxx baseline due to ….
C) monitoring major highway classification changes with osmcha.org
“Fixing” classification works only temporarily until someone comes uninformed and changes them again. OSMcha.org can filter changes based on major road modifications under “Reason for Flagging”.
