Ohio Revised Code Title I. State Government § 128.15

(B)(1) Upon installation of a countywide 9-1-1 system, the board of county commissioners may direct the county engineer to erect and maintain at the county boundaries on county roads and state and interstate highways, signs indicating the availability of a countywide 9-1-1 system. Any sign erected by a county under this section shall be erected in accordance with and meet the specifications established under division (B)(2) of this section. All expenses incurred in erecting and maintaining the signs shall be paid by the county.

(2) The director of transportation shall develop design specifications for signs giving notice of the availability of a countywide 9-1-1 system. The director also shall establish standards for the erection of the signs and, in accordance with federal law and regulations and recognized engineering practices, specify those locations where the signs shall not be erected.