“I still think this was pilot error or careless maintenance or both.”
Careless/cheap/no maintenance is the most likely cause.
With hindsight we might be able to work out something that the pilot could have done to avoid the bridge support (and hit something else) but that is unlikely to be anything that the pilot could reasonably have been expected to work out in the situation.
When I say pilot error, I mean from the moment he agreed to take the job, not necessarily his actions after trouble began.
Here’s an informative interview about pilots ...