It's funny how I travel a lot but I have some kind of mental block when it comes to approaching girls on a bus, train or an airplane, and I think the reason is that you're both stuck in the same place for a long time, so there's more margin for error since you'll probably be talking to her for the duration of your trip. Whereas in a coffee shop or on the street, I feel more relaxed and I don't have to keep the interaction going for more than 15 min. I don't know. What's your take on that?
A lot of people on here have that "one venue" that they're not comfortable/confident approaching in for whatever reasons. For me it's Walmart and certain parts of my mall because there are so many bystanders. But for me I go to Walmart a lot and the place with the highest abundance of women is in the mall for me so I had no choice but to slowly start hacking away at my anxiety and see it for what it really was. I've gotten to the point where I can almost always approach anywhere in these venues. I'm still working on Walmart but I'm getting a lot better there.
I usually think "what is the worst case scenario?" and then ask myself if I could live with myself if that happened. This may not work for you but let's analyze what is the worst case scenario for a bus ride. I guess worse case scenario on the bus would be you go talk to the girl tentatively and she gets creeped out by your approach, gets awkward and closes off. Then you go sit back down in your seat and continue doing whatever it was that you were doing. Worse worse case scenario is that you fuck up the approach and the girl says "uh this is really awkward" with a disapproving look on her face, and then on your way back to you seat you get a weird look from some guy with a mustache and a guy with a tie on says "Hey better luck next newb huh huh." . And that's worse case scenario you have 3 people that think you're a weirdo so you go sit down, put your ipod on, and some sunglasses, and sit back and think about how badass you are for facing your fear. But that's highly highly unlikely to happen.
I didn't write that to scare you off but hopefully it makes you realize how not big of a deal that would be. If that happened to you a week would go by and it wouldn't be significant at all then. Just a funny story you could tell your friends about "you'd never guess how bad I messed up this conversation the other day!"
As far as this goes
I mean should you cut the interaction to 20 min max on the bus?
If you know you're both going to be on the bus ride for a while you can wait till the 30 minute mark and go approach then so you don't have to worry about getting rejected and having to chill in the social pressure for the remainder of the trip.
But I would probably go approach, talk, and depending on how well the conversation goes make up your mind what you want to do then. If it goes well see how far you can go before it gets awkward. If it goes bad then just excuse yourself from the conversation and tell her it was nice meeting her. If it goes well and you don't want to continue talking for 5 hours ask her when she gets off and tell her you'll need a break from xyz (have like homework or some excuse to go work on something of some sort) and come chat with her a little bit later towards the end of the trip.
My suggestions. Main thing is you go out and start approaching women on the bus in general. It sucks but you might be surprised who you'll meet! As far as leaning into fear goes you could wait for a good opportunity when there aren't a lot of people on the bus to approach a girl and do it then so theres not as much social pressure. You could open with an indirect opener and just try and start a conversation. In fact if you're just really nervous to hit on a girl I would make starting a conversation in general a good goal before going full fledge direct.
-Rob