exemplary credit: two commuter train, light rail, or subway line

Great question. By the literal LEED language, this would obviously qualify as a bus, not a rail line. However, based on intent and function, the BRT should act as a rail or subway line. Are you able to prove that the BRT line(s) in question have the speed and capacity of an average subway? If so, then you may have an argument for categorizing the BRT as a subway. From what I know, however, BRT statistics fall somewhere between subways and regular buses. I don't know how GBCI will respond. Pittsburgh, PA has both a old bus rapid transit system (its "busways") and a lot of LEED certified projects. You may be able to find out if any of those projects have crossed this bridge before.