The right-of-way is defined by state statutes as "the land, or interest therein, acquired for or devoted to a highway." What this means is that the highway authority has the sole responsibility to determine what gets built within this designated area.
Right-of-way can consist of privately owned property that is designated for right-of-way purposes, which is often called a dedication of right-of-way. In this situation, the landowner does legally own the property but basically transfers over that property to the highway authority for as long as it remains a public road. The highway authority then determines what can or can't be done within this area.
If the land within the right-of-way has been given to the highway authority by quick claim deed or similar fashion, then the public body is, in fact, the landowner for that property.
Regardless of the type of right-of-way that exists for a given road, the highway authority must approve of any work performed within the right-of-way. Nothing should be installed, placed or built within the right-of-way without the prior approval of the appropriate highway authority. For road district (township) roads the Highway Commissioner must give the approval. For County roads the County Engineer gives the approval and for State roads the Department of Transportation gives the approval. It is very important to contact the appropriate authority before a person installs anything within the right-of-way. It is illegal to place anything on the right-of-way without approval from the appropriate authority. Entrance culverts, mailboxes, signs, fences, etc. can all impose obstacles that could make it difficult for the highway authority to perform services associated with the maintenance of roads.
If you don't know exactly where the right-of-way line is, contact the appropriate highway authority. The right-of-way on state and county roads are usually well documented, but township roads often times are not. However, the individual Township Road Commissioner's can usually tell you where it is.
Before doing anything within the right-of-way, please contact the appropriate highway authority!