This bridge is a double span, seven panel, pin connected Pratt through truss and remains open to railroad traffic.
Photo taken by Robert Elder in March 2007
BH Photo #111734
Thanks, Michael. That makes sense.
In my travels I've found quite a few Pin-connected railroad bridges where the first panel or two of the bottom chord is a built up compression member, so it was likely an original feature. I always figured it was due to the heavier/faster rolling stock that was expected where the last panels needed to handle compression forces. I've yet to see a highway bridge with this arrangement.
On many bridges with eyebar bottom chords, the eyebars get thicker towards the middle of the span. See photo #40 for this abandoned wagon bridge as an example:
BUT...on this bridge the bottom chord is thickest at the ends of the span. Perhaps this span had thinner eyebars at the end of the trusses originally. I need to have a closer look, but I would not be surprised if those I-beams on the ends are modifications that might have replaced eyebars at some point in time.