Photo taken by David Backlin in July 2011
BH Photo #203375
I was noticing those piers as well - I am not familiar with the term "auxiliary piers", but that seems to describe their function. I did a brief NBI search for this bridge, but have not found it yet.
The old US 75 alignment is an interesting discovery. This is a good find.
Interesting to see a skewed alignment with perpendicular abutments and auxiliary piers.