Ohio Rev. Code Ann. § 5543.11

The county engineer may establish the grade and width of sidewalks constructed along or connecting the public highways, outside any municipal corporation, and designate the character of construction, and have general supervision of such sidewalks. This section and section 5543.10 of the Revised Code relating to the construction of sidewalks, shall not prevent the director of transportation, county engineer, or board of township trustees from granting permission to the abutting property owners to construct sidewalks in front of their properties and along the public highway, but such sidewalks shall be constructed subject to the approval of the proper authorities.