Organizing a catastrophe-Love parade in Duisburg

Recently organized (or mis-organized) Love Parade in Duisburg cost more than 20 lives. It has to be said that quite a few large events went well, without major tragedies, thus critics should agree that organization rules if properly implemented could provide adequate safety.
Markt & Technik, Heinz Arnold is lamenting on insufficient use to available technologies gered to serve and to protect such as digital police radio, more explicit by-laws, and other ideas.
From where I am standing, I know it is hard to predict human crowd's behavior in a suddenly stressing situations.
Technology might be helpful, certainly. But common sense, a degree of mistrust and a healthy dose of precautions, provisions for expanding spaces, exits, and crowd control in real time, and with macro-management.

We hope such tragedy wont happen again. But as it was said about wars: if you want to avoid a catastrophe, prepare for it.