Apparently this section of the pedestrian bridge was installed within the last week or so. The likely cause of this collapse is one of the following:
1. Error(s) in the design.
2. Error(s) in the construction procedures (maybe more likely than a design flaw, with a precast concrete bridge).
3. Materials that didn't meet the design specs.
Of course, this is all based on the assumption that the bridge wasn't struck by an oversized truck or something of that sort.
That was my Professional Engineering opinion as well
This is supposed to be a suspension bridge. The cables weren’t installed yet. Another poster said a crane dropped something on the span that caused it to collapse.