I'm surprised it wasn't stripped out when scrap prices were high.
Probably too big and too dangerous to handle without heavy equipment, whether it was an "official" sanctioned scrapping, or illegal. And presumably it's not going to be cost-effective to get cranes out there etc.
I don't think you could just show up with a torch and an angle-grinder and just hack away on the bridge, then there's the issue of getting the steel or iron out of there even if you did cut it up, or collapse the bridge in the most lazy/dangerous way possible.