It seems to me that the preposition usage corresponds to the boarding language pretty closely. Where “on” sounds most natural is also where “boarding” seems most appropriate.
The schedule/route condition makes a lot of sense to me. Consider a bus converted to personal use as an rv:
“I boarded my bus and drove to the mountains” is a valid English sentence, but it sounds odd to me. But if it’s still a regular bus and drove->rode it works.
“I drove to the mountains in my bus” sounds better. Same vehicle as a city/school bus, different context. Change to a regular bus and drove->rode doesn’t sound right without also changing “in my” to “on the”.
It seems to me that the preposition usage corresponds to the boarding language pretty closely. Where “on” sounds most natural is also where “boarding” seems most appropriate.
Here is one linguist’s take, with proposed usage cases at the end: http://itre.cis.upenn.edu/~myl/languagelog/archives/005224.html
The schedule/route condition makes a lot of sense to me. Consider a bus converted to personal use as an rv:
“I boarded my bus and drove to the mountains” is a valid English sentence, but it sounds odd to me. But if it’s still a regular bus and drove->rode it works.
“I drove to the mountains in my bus” sounds better. Same vehicle as a city/school bus, different context. Change to a regular bus and drove->rode doesn’t sound right without also changing “in my” to “on the”.