The premise behind these simulations is that giving directions to crowds will improve flow of people.
It's a mighty big assumption that the folks in the crowds would follow a signal to "slow down". Between the culture in general (ever see a tidy British style queue in the middle east?), and the general human dynamics of large crowds of people, I don't have much hope of this being a success.
Perhaps a better solution would be to increase the time window for this event- spread the crowd over a few months instead of a few days.