605 ILCS 5/5-501
When it is necessary to construct or repair any bridge, culvert, drainage structure or grade separation, including approaches thereto, on, across or along any public road in any road district in the county, or on any street in any municipality of less than 15,000 population in the county, or on or across a line which forms the common boundary line between any such road districts or such municipalities, in which work the road district, or such municipality is wholly or in part responsible, and the cost of which work will be more than .02% of the value of all the taxable property in such road district or municipality, as equalized or assessed by the Department of Revenue, and the tax rate for road purposes in such road district was in each year for the 2 years last past not less than the maximum allowable rate provided for in Section 6-501 of this Code, or the tax rate in such municipalities for corporate purposes was in each year for the 2 years last past for the full amount allowed by law to be extended therein for such corporate purposes, the highway commissioner, the city council or the village board of trustees, as the case may be, may petition the county board for aid, and if the foregoing facts shall appear, the county board shall appropriate from the "county bridge fund" in the county treasury a sufficient sum to meet one-half the expense of constructing or repairing such bridge, culvert, drainage structure or grade separation, including approaches thereto, on condition that the road district or municipality asking for aid shall furnish the other one-half of the required amount. In counties in which a property tax extension limitation is imposed under the Property Tax Extension Limitation Law and the imposition of the property tax extension limitation prevents a road district from levying taxes for road purposes at the maximum allowable rate, a road district may retain its eligibility if, at the time the property tax extension limitation was imposed, the road district was levying at the maximum allowable rate and continues to levy the maximum allowable amount after the imposition of the property tax extension limitation. If, however, the road district has increased its tax rate for such purposes to a rate in excess of .05% but not exceeding .25%, as provided in Section 6-508 of this Code, the amount required to be appropriated by the county shall be in accordance with the provisions of Section 5-501 of this Code, to the extent that the County and township rates are identical. For purposes of this Section, the maximum allowable tax rate for the 2 years last past shall be determined by using the last certified equalized assessed valuation at the time the tax levy ordinance was adopted.
When it is determined by the county board to grant the prayer of the highway commissioner, city council or village board of trustees asking for aid for the construction or repair of such bridge, culvert, drainage structure or grade separation, including approaches thereto, the county board shall thereupon enter an order directing the county superintendent of highways to cause plans and specifications for such improvement to be prepared.
Thereupon the county board shall order the improvement made, either by the letting of a contract in the manner authorized by the county board, or by doing the work itself through its officers, agents and employees. The work shall be performed under the general supervision of the county superintendent of highways, and when the work has been satisfactorily completed to meet the approval of the county superintendent of highways, he shall so certify to the county board, which certificate shall include an itemized account of the cost of all items of work incurred in the making of such improvement, and shall show the division of cost between the county and the participating agency, and he shall cause a copy of such certificate to be filed with the clerk of the participating agency. The county board and the participating agency undertaking such work shall thereupon make final payment for the same.
605 ILCS 5/5-501