Dave,
I think the postcard you added is actually for a different bridge around the corner. Strange that a postcard would feature a stringer, but count the railing balusters and note the flat deck (no hump) and is thus seems to match the stringer. http://www.historicbridges.org/bridges/browser/?bridgebrowse...
My ancestor John Wallace and his son Charles Wallace likely worked on this bridge. Charles was Masonry Inspector / Superintendant on National road from Wheeling to West Ohio.
We have family records of Charles and he must have learned the trade from his Father to be that high ranking.
You are correct Nathan and I appreciate you pointing it out. Kind of strange indeed. I have removed the image.