Given the structural condition of the bridge and the listed ADT, there really is absolutely no reason to replace this bridge. However sometimes counties will claim some farmer needs to get his combine over the bridge and therefore a bridge with enormous deck width costing large amounts of tax dollars is needed. However this bridge appears to be located on an extremely narrow two track dirt road. I doubt a combine would fit on this road, therefore a wide bridge is not needed. For the purpose of saving taxpayer dollars, while also preserving history, I would strongly recommend the county hire a firm experienced with historic bridge restoration and rehab this bridge for continued light vehicular use which would likely cost a fraction of replacing the bridge.
Judging by the road, why would they even want to replace that bridge?
As roads in this area go, it's really not all that bad. Just a half mile north, past the junction, is another matter entirely. I suspect that there is, in fact, rather a lot of farm machinery traffic through here, and the bridge really is rather narrow. Many bridges in Knox county have been replaced with flat concrete spans with low barriers to support farm traffic... this one is just down the list a ways. I'm glad I was able to get a picture when I did. These pictures predate the erection of the "road closed" signs, by the way.