[keithpeter]

"But here I was, helpless. The only thing I could do was direct her to BART and join the rest of the class inside. "

I'm a teacher, and if this happened to one of my students on an official College trip (which, in the UK, would have been documented and approved in advance with a risk analysis &c, and yes even for adult students) I would probably be on the phone to the principal.

Given they way things sound in this case, I would have had to consider options. I'm assuming the teacher in this case was also driving the transport.