Escalators are not your friend, as this story proves. In D.C. they've had to add all kinds of funky things to keep people from getting hurt, and even then I think something like 20-30 people have been injured and killed on them since the system opened in the 70s.
I actually saw a jam-up happen at an airport "moving sidewalk", a similar contraption. I was running late and decided to trot alongside the thing. Just as I came even with the end of it some twit with one of those three-ton carry-on roller things got a wheel caught in the mechanism. The sidewalk kept moving and it looked just exactly like someone had dropped a rock in a fast moving stream... people just shot over, around, and on top of this monster bag.