605 ILCS 5/6-201.7
Construct, maintain and repair and be responsible for the construction, maintenance and repair of roads within the district, let contracts, employ labor and purchase material and machinery therefor, subject to the limitations provided in this Code. Contracts, labor, machinery, disposal, and incidental expenses related to special services under Section 6-201.21 of this Code constitute maintenance, for purposes of this Section.
Except for professional services, when the cost of construction, materials, supplies, new machinery or equipment exceeds $30,000 , the contract for such construction, materials, supplies, machinery or equipment shall be let to the lowest responsible bidder after advertising for bids at least once, and at least 10 days prior to the time set for the opening of such bids, in a newspaper published within the township or road district, or, if no newspaper is published within the township or road district then in one published within the county, or, if no newspaper is published within the county then in a newspaper having general circulation within the township or road district, but, in case of an emergency, such contract may be let without advertising for bids. For purposes of this Section "new machinery or equipment" shall be defined as that which has been previously untitled or that which shows fewer than 200 hours on its operating clock and that is accompanied by a new equipment manufacturer's warranty.
605 ILCS 5/6-201.7