The current situation is yet another example where the classification of vehicle-types in OSM is contradictory to both itself and international conventions.
I support the point of westnordost that we have to make a distinction between *construction *and use.
And given both the practical situation and commonly adopted international conventions (national legislations are variations within these frameworks) a hierarchy can be made:
-First and foremost the classification is defined by the construction, this defines in which category a vehicle is categorised for admission on the road (in UN-ECE: classes M for vehicles constructed to carry passengers; classes N for vehicles constructed to carry goods).
Once on the road, a vehicle designed to carry passengers (class M in UN-ECE) can generally be used in different ways: both in public transport and private transport, mostly without altering the construction and legal registration.
There are no different vehicle classes within UN-ECE based on whether it is designed for public or private service, the subclasses are based on number of seats (M1 less then 9; M2/3 more then 9) and weight: (M3 >5t).
See for example (UN ECE has 56 member countries, not only in Europe, but also US and Russia; ; the exact numbers for seats / weight in other countries may vary, but the principles are generally the same )
The opposite is much harder however: if a vehicle constructed to carry goods was to be used for carrying passengers, it generally can not be used for carrying passengers without reconstruction and legal re-admission. The construction type of a vehicle also mainly define which type of drivers license is needed to operate it.
Just like the common international conventions for vehicle admissions, also the conventions for traffic regulations (Vienna convention) does not make an a priori difference between in traffic signs for the usage of buses (it does however n road markings for lanes)
In national traffic legislations (how to behave on the road with a given vehicle) however, governments can choose to make further distinctions in traffic signs when allowed in such conventions, as quoted above for Germany.
Also in the Netherlands traffic legislation a difference is made, both in road markings and traffic signs, allowing or prohibiting access for:
-either all busses (“Autobus” performing either public or private transport at that moment: sign C7a; C7b, like second picture in the post form @dieterdriest)
-or only busses performing public transport at that moment (sign F13)
From this international use a general hierarchy can be derived:
(for ALL busses; motor_vehicles constructed to carry more passengers more than a regular passenger car as defined in national legislation)
To be divided in:
–**Busses in use for public transport **
–**Busses in use for private transport **
But when you try to relate this to the main access-scheme in you get lost on the woods:
there seems to be no general term for all busses in OSM, since the general key:bus is -counter intuitively- already more specifically defined as “a heavy bus acting as a public service vehicle” .
And furthermore to make it more confusing the wiki page for key:bus is just a redirect to key PSV, which might suggest a much more synonumus relation than is actually the case
Within the construction categories there now is both tourist_bus and coach, and it is not clear whether one is a subclass of another (although coach seems a more general term to me, since not all coaches transport tourists).
So if you would like to tag that a road is closed to all busses; you would have to tag all of
It is probably too late and too much work to change the OSM definition of key:bus to the much more commonly understandable wider scope of all busses, but a clear general term could still be introduced.
And at least the hierarchy between key:coach and key:tourist_bus could be made explicit on the main access-page: is tourist_bus a sub-class of coach?
If that is the case, a road closed for all busses would need one tag less (no more tourist_bus)