I didn't say a design flaw brought it down. I have no idea what did initiate the collapse and even said so. I implied it was a poor design for the whole thing to come down because of a failure in one section. This isn't a suspension bridge. The adjacent bridge has a much better design. The Oakland bay bridge suffered heavy damage in the '89 quake and one section failed and dumped cars into the bay, but the whole bridge did not collapse due to the failure of the one section.
Think of a stone arch. Pull one stone and the whole arch fails.
In a truss bridge a failure of any segment likewise will compromise the entire structure.
The sections that fell in the bay bridge were just that. Sections of roadbed that broke. There is no parallel to this bridge.