The Great Catharpin Mystery Caper: Who Dunnit?

The signs were up for about six hours, and then they went missing.

Who could have stolen the signs?

Surely it wasn't anyone driving along Catharpin Road because everyone wants that ditch fixed.  It's a serious safety hazard that has gone on for three weeks now.

It is unlikely any average taxpayer stole the signs because none of them want to pay the bill to fix the ditch that was created by a dump truck headed to the Smith Dump.

So, if not them, who in the world would want to steal those signs?

Any ideas Mr. Smith?