My suspicion is an overloaded truck. The bridge has been in this condition for several years - at least since I discovered it about 2006.
I have noticed an interesting fact about this particular bridge. Although the floor beam is twisted and the wood deck has partially collapsed, the rest of the structure seems to maintain good integrity. I need to have a closer look, but I suspect that the pin-connections absorbed most of the shock that was not absorbed by the floor beam.
I am curious if we would have seen the same result had the bridge been riveted with gusset plates instead of being pin-connected.
Additionally, if the construction date of 1888 is correct, then this bridge may be constructed of wrought iron instead of steel. Because wrought iron is more malleable than steel, I am wondering if that allowed the floor beam to absorb more of the shock instead of transferring it to the rest of the superstructure.
This bridge might make a good case study. So, far I have not heard of any replacement plans. Bourbon County has demolished a couple historic bridges in the last couple of decades. That being said, they have a good track record overall as several HBs are being maintained throughout the county.
And how about that steel floor beam, twisted like a piece of wire? Looks like the work of an overloaded truck manned by a brainless driver (had a rash of those lately).
Judging by the decent shape of the remaining wooden stringers, I would guess that something pretty heavy fell through it!
What happened here Robert? Overload through the floor? Or just age?