That happaned to me one time.
And she was reading music. All I had to do was to ask her:
"I'm curious. HOw do you know wich notes are you singuing?"
But guess what...
I did not start the conversation. And I still regret it. I must force myself to approach next time.
Anyway, all you have to say is:
"I hate waiting for the bus alone, so you're gonna have to put up with me
"
(A wink when approaching is always the cherry on the top of the cake).
Don't forget: Smile, look in her eyes, be nice and tottaly alpha (like all of you can be if you really want).
That's it. Just ask her something then. In my opinion you should start asking something like:
"So, where are you from?"
Or something about whatever's happening arround you.