Ohio Rev. Code Ann. § 4511.98

The director of transportation may establish speed limits within construction zones that vary based on the type of work being conducted, the time of day, or any other criteria the director may consider appropriate. The director, board of county commissioners, or board of township trustees shall cause signs to be erected advising motorists that increased penalties apply for certain traffic violations occurring on streets or highways in a construction zone. The increased penalties shall be effective only when signs are erected in accordance with the guidelines and design specifications established by the director under section 5501.27 of the Revised Code, and when a violation occurs during hours of actual work within the construction zone.