When Shep first started his rants about the overpass, there were thousands of people (remember when he was speaking to the City Police spokesman). I saw myself a truck pull up and off load water. The next day, there were only hundreds on the bridge (the others had found their way to the Super Dome or had walked on down the road and been picked up.
I'm sure the feds, when they were able to contact Nagen, were assured it was being taken care of. I heard that at one point, the city denied there was a problem.
We'll find out all the facts, hopefully sooner than later.