Yeah, it looks like modification by collision with 14 ft. high trucks!
It certainly appears the railroad decided they needed more load carrying capacity on that span. So with the grace of an artist they simply scabbed up ugly concrete and steel strapping under a somewhat graceful arched span.
It also appears the notorious over height truck likes to victimize this bridge.
Another thought on that note. The bridge could have been hit and damaged so bad that this ugly repair was the only thing the railroad could do to save the span.
For the life of me I don't understand why they don't install templates before a bridge so that an oversized vehicle would harmlessly hit it before damaging a bridge. It would make a lot of racket or even damage the road vehicle but would prevent damage to the bridge. Better to damage only one vehicle than bring down a costly bridge.