It's a difficult question. If you go by the dictionaries define language rule, it's improper, but if you go by the speakers define language rule, it's OK, mainly because it's understandable. (Please note, I haven't said it's an OK usage. Some days I'm more of a prescriptive grammarian than a descriptive one.) The real test will be if it catches on with other bus drivers (or already has) and from them spreads to the non-bus-driver community. The only verb express that I know is transitive, but neither does it mean "to become an express (bus)". Just my tuppence.
...and yet it doesn't seem unlikely to have someone order merchandise and be happy to hear "We'll express it to you overnight."
Verb, transitive, in this context, certainly? An outgrowth of the adjective "express," fast because of limited stops, as opposed to "local," stopping at all points along the way. (Lexington Av;enue, here we come!)
Although I must say I've never heard it verbed in the Chicago sense above.
Actually, Jerry, I wasn't on the bus. I read about it in the paper. Evidently the announcement was slow enough that it startled the passengers. They heard, "This bus will ex....," and some of them thought the word was going to be "explode!"
Another definition for "to express" is that process by which a lactating woman removes milk from her breast to be put into another container for later use in feeding a child.
If I were on a bus which announced it was about to express, I might be concerned about the stability of its transmission fluids, etc.
