Ohio Rev. Code § 5521.02
The board of county commissioners of any county may co-operate with the director of transportation in the elimination of railroad grade crossings on the state highway system, and in the construction or reconstruction of bridges and viaducts, together with the approaches thereto, and may pay such portion of the cost of any such work as is agreed upon between the board and the director. Such board may co-operate with the director in the preparation of comprehensive transportation and land use studies and major thoroughfare reports and in establishing, constructing, reconstructing, resurfacing, or widening a state highway, and it may, under such circumstances, pay any agreed portion of the cost of such work. Any board desiring to co-operate as provided in this section may, by resolution, propose such co-operation to the director, and a copy of such resolution, which shall set forth the proportion of the cost and expense to be contributed by such county, shall be filed with the director. Where any portion of the work covered by such proposal is within the limits of a municipal corporation, such proposal shall be accompanied by the consent of the municipal corporation to the doing of such work, evidenced by proper legislation of its legislative body, unless such consent has already been given to the director. The boards may co-operate with the director in the cost of obtaining right-of-way required for or in connection with any state highway improvement or repair contemplated by the director, and may pay any agreed proportion of the cost of such right-of-way. Unless expressly restricted, the authority granted to boards by this section to co-operate with the director shall extend to all portions of the state highway system, both within and without municipal corporations, subject to the condition that the consent of a municipal corporation be given to the performance of any work within its limits.
When the board or the legislative authority of a municipal corporation co-operate with the director and assume all or a part of the cost of establishing, constructing, reconstructing, resurfacing, or widening a state highway, such board or municipal authority may specially assess such portion of the cost assumed on behalf of the county or municipal corporation as is deemed proper. In making such assessments the board or municipal authority shall proceed in the manner provided for the levying of special assessments by the board of county commissioners or municipal authorities for road improvement.
The board or municipal authority may issue notes and bonds in anticipation of the collection of the special assessments provided for by this section as is provided with respect to special assessments for the construction of highway improvements under the sole authority and control of such board or municipal authorities.
R.C. §5521.02