Why would both ends of the expanse collapse simultaneously, and boom! fall instantly?
One side started to fall first. Judging from the wreckage, both sides failed at approximately the same place, the second side being WAY overloaded trying to hold up both sides.
They did not fall simultaneously. In fact, the north side didn't collapse until a full quarter-minute (15 seconds) after the south end started falling. This is shown clearly on a surveillance video of the collapsw (looking toward the north shore).