The key reason NSW police told marchers to turn around

Another risk factor was the makeup of the crowd. This was not a uniform adult group. Including families, children, old people. In a crowded crowd, they are often smaller or less physically talented. A different crowd requires conservative security assumptions.

In addition, rain changes the way people move, Just as it changes the flow of traffic. On the road, even a slight shower can slow down and cause bottlenecks. The same applies to the crowds on foot. In particular, when people hold umbrellas, they take more space and act more carefully. Basically, physical footprints grow. Studies show that Pedestrian flow may fall to 20 to 40 percent in one directionAnd when people move in both directions, up to 50 percent.

Police intervention was far from perfect. The first NSW police geo-faded text message, Posted at 15:00“Message from the NSW Police: In consultation with the organizers, March must stop because of public security and wait for more instructions.”

The aim was to slow down the upstairs crowd. At the northern end of the bridge with a potential jikle. Whether the message is open enough to reach this conclusion is controversial. While providing a subsequent follow -up message A clearer directive, Protesters may have interpreted the message differently. Compliance is never 100 percent. Some may have ignored him, think that he was spam, or not believed to be serious. Some may have stopped while others have stopped. This meant creating a two -way pedestrian flow that adds its own risks and complications.

However, if there were serious concerns that the northern end could not be cleaned quickly enough, it was probably necessary to keep the flow flow back.

The fact that no one is injured does not mean that there is no risk. During the political protests in other countries, they had crowded paste. I can point Almost a dozen example.

Does a crowd of crowds take place without police intervention? The probability was low in my guess. More likely results, discomfort, pressure and crowded chaos could be – sometimes similar to what we see in live moments, The place where people are worried and followed by complaints.

But that’s here: If he had reached this point-even a wrinkled situation even without the injury-we will probably give a very different speech today. We were asking why the police hadn’t entered before.

This is the truth of the risk management. These decisions are not based on a trip. In real time, they are made with limited information, under pressure and taking into account a rule: When the potential result is serious (injury or death), even a small chance can take action.

Australia has traditionally a low tolerance for public security risk. However, this is a large part of the rare causes of large crowded disasters in this country, but Partner in elsewhere. The police reaction on Sunday was consistent with this security culture.

Milad Haghani is a professor of urban risk, flexibility and mobility at the University of Melbourne.