In Amsterdam airport they are pretty unalarming, just pairs of automatic doors a few paces apart. From a brief look at this video, you have to momentarily stop,

In Amsterdam airport they are pretty unalarming, just pairs of automatic doors a few paces apart. From a brief look at this video, you have to momentarily stop, and there is a hint that you might not be able to continue. That's just bad usability. The ones in Amsterdam allow you to carry on walking at a normal pace, and they act like normal automatic doors (in one direction). I'm sure there are people who walk through them every day and don't even notice them. The last time I was in Atlanta, they had a similar thing, but more subtle. If I remember correctly, they have a bank of escalators, but all of the escalators go in the same direction. As I found out when I got to the top, and had to go through security again to get back down...