As a student, I would sometimes start a stampede in the underground simply by gradually starting to run. All it takes is a couple of other people to follow suit and some crowd instinct kicks in so that almost everyone suddenly feels late and left behind.
Moving walkways, of the type used in airports, apparently cause people to take fewer paces per second than when walking normally -they get a rest but the flowrate of people is only very slightly increased over the case in which there is no walkway at all.
Today’s invention is therefore a way to get crowd volumes moving faster. Travelators would have walls fitted on either side onto which images of people walking in the same direction would be projected. The speed of the projected walking would be fast but not so fast as to look incredible.
This would encourage passengers to up their pace, so as not to be left behind.