I believe it was a temporary bridge that they used during the renovation to dismantle and rebuild the bridge without putting temporary supports in the river. I think they had to use it during the project because the Sandusky is considered a scenic river. If I remember right the historic truss was completely taken apart and galvanized in Cambridge, Ohio, before being reconstructed at Indian Mill. Photos coming soon.....
Looks like some sort of traveler they used to move the bridge, based off http://www.dailychiefunion.com/wp-content/uploads/2015/08/DC...
Just looked at that street view and about choked.
I know they moved the bridge off site in 2015 and had it repaired and galvanized. I'm not sure what that monstrocity of a structure is in it's place. I was concerned that Ohio had done an about face and swapped another historic metal truss for a fake covered one.
Please find attached photos I dug up from my email archive from Tom Barret at ODOT showing the unusual way in which this temporary truss was used to roll the truss off the river, and to launch the bridge after being galvanized. US Bridge Company was the contractor for the project.