For crowd-control specialists, law enforcement, city admin and emergency response groups.

Study: contrary to popular belief, crowds are not mindlessly irrational but act with intent based on shared identity.

In other words, groups of strangers cooperate when faced with adversity. Cooperation can be peaceful or violent, depending on the stimulus. Police reacting heavy-handedly can provoke riots due to a shared grievance while natural disasters foster a sense of community.

This article does not address the issue of crowd stampedes. During a stampede, a different part of the brain is activated. The ‘lizard brain’ which is responsible for individual survival takes over.

The intimacy of crowds at Aeon Magazine.