Any contract made by the director of transportation under Chapters 4561., 5501., 5503., 5511., 5513., 5515., 5516., 5517., 5519., 5521., 5523., 5525., 5527., 5528., 5529., 5531., 5533., and 5535. of the Revised Code shall be made in the name of the state and executed on its behalf by the director. No appointee of the director, other than the assistant directors of transportation, may bind the director in a contract, except when given general or special authority by the director.