This is my two cents: After watching yesterday's filming on YouTube of the bus flip, and Shia's "hand hang", I came to the realization that the entire filming of Chicago scenes may be a tactic of marketing from PM & DW. They could have filmed different parts at different locations such as the Universial back lot like they did in TF1, however, they chose to film the major climax, and big portion at local streets. Think about it. The news coverages, the road blocks, traffic and the amounts of civilians to make time out their day to catch a glimpse of the stars and filming. It's creating huge buzz for the film - a whole lot more than TDK when they filming in Chicago. I think it may work.