I dont understand....... Was this a legit "walk/parade"? Because I have never seen one where they don't have police that close the intersections for them. In fact I thought it was a requirement that you have the police there to do that and get permits or whatever etc. So you don't have shit like this happen.
Ya, you can't just close down intersections because you want to. If you don't have police there for large events, then you have to go in groups to let some traffic through.