Barnstorming on an Invisible Segway

That sounds like space-filler public service announcements, which are fine when it's putting a "watch the gap" notice on the subway train, questionable when the subway system puts a recorded message on the PA starting "This is an important message from the New York City Police Department" (it's not, it's the same thing they've said a million times, because they seem to have acquired a DJ's fear of dead air), and completely unjustifiable when it's individual interruptions of your day to tell you ordinary facts.