It looks to me like they were close to clearing the bridge, just barely tapped it with the bridge on the ship, and that brought it down.
The ship seems to be very high in the water, perhaps that's part of the issue and they needed ballast. Or the water could be high, or they could have tried to go under the wrong span for reasons unknown. Also, in the reading I did a week ago, it wasn't clear to me if they went under THIS bridge previously or not.