Ohio Rev. Code § 5521.11
Chapters 5501., 5503., 5511., 5512., 5513., 5515., 5516., 5517., 5519., 5521., 5523., 5525., 5527., 5528., 5529., 5531., 5533., and 5535. of the Revised Code do not prohibit the board of county commissioners, at the expense of the county, or in co-operation with the board of township trustees, or municipal authorities, at the expense of the municipal corporation, or in co-operation with the board of township trustees, from constructing any part of the state highway system, or the bridges and culverts thereon, within such county, municipal corporation, or township. The plans and specifications covering any such proposed construction by the board of county commissioners, municipal authorities, or the board of township trustees shall be first submitted to the director of transportation and receive his approval. Any such construction shall be under the supervision and inspection of the director, his agents, or employees. The costs and expenses of such inspection and supervision shall be paid by the county or the municipal corporation as a part of the cost and expense of such construction. No estimate on account of any contract covering any such construction shall be paid until it has been first submitted to and approved by the director, or one of his deputies or engineers designated by him for that purpose.
R.C. §5521.11