Disaster based behaviour

People always assume that a disaster will involve running and screaming and people clawing at each other to get past.  Not only is that often not entirely true (most people have families or friends with them, notable instances of people in crowds helping each other have been found) as it's less that no one cares or is trying to help and more than it's difficult in a tight crush of people to help those who have slipped (if you even see them) but it can even be the complete opposite of that.  Sometimes people will just pretend that everything is normal.  Weird but true.  So if you're going to be running a crowd in a risky situation then you can create a more unique situation by including a bunch of people who have chosen to wait.