MrSnuggles
“Bound” is part of the verb “to bind” which would make me hesitate for those extra seconds about the meaning of this instruction.
Except that in this case, it isn’t. The “bound” in “the train bound for somewhere”, or “homeward bound” or “south-bound” is an independent adjective that originally means ready (i.e. in a state of readiness), and has an etymology which has nothing to do with the verb bind.
Which I think only reinforces your point that it could cause even an advanced English speaker to hesitate if they weren’t familiar with the phrase!