It varies by state, but this is getting into semantics that only the courts can really decide on, and only if there’s a really good reason to.
In North Carolina, horses are considered vehicles for most purposes. But regarding intoxicated driving, horses are non-vehicles while bicycles and lawnmowers are vehicles.
California regulates horseback riders by analogy to vehicles, but laws distinguish between vehicle drivers and horseback riders:
Every person riding or driving an animal upon a highway has all of the rights and is subject to all of the duties applicable to the driver of a vehicle […], except those provisions which by their very nature can have no application.
The driver of any vehicle shall yield the right-of-way to any horseback rider who is crossing the highway at any designated equestrian crossing which is marked by signs […].
The upshot is that vehicle=* doesn’t clearly align with U.S. law, certainly not well enough to associate that term with a specific sign, as in Vienna Convention countries. In that GitHub discussion, others made the point that it might not be uniform in Europe either.
More relevant to this thread, Oregon lumps a variety of species in with horses, in case anyone decides to be clever and ride a hog down the highway:
When riding or leading a horse or other livestock on the highway, a person must keep a lookout for vehicles and use caution to keep the animal under control. […] This section is only applicable if the livestock is an animal of the species of horses, mules, donkeys, cattle, swine, sheep or goats.
Maybe someone should compile a table of which jurisdictions treat which species like horses. Please include a row about zebras so we can finally get some closure about zebra crossings.
I can’t speak to the first two signs, since I’m not very familiar with Japan or Russia. But the third sign is from the U.S. The official name of sign R5-6 is “No Bicycles”. California sometimes pairs it with an educational plaque to reinforce the message:
Even so, as long as pedestrians are allowed, the legality or practicality of walking a bike in the presence of this sign really depends on the situation. There isn’t a hard-and-fast rule in reality.
