[With regard to any county which is exempt from the provisions of Section 19-2-3, this section shall read as follows:]
Before any road, or any part thereof, or any bridge shall be let out to contract where the amount of the contract will exceed One Thousand Five Hundred Dollars ($1,500.00), the road commissioner, or engineer if there be one, shall inspect the road or part thereof or the bridge so proposed to be contracted, and shall carefully note the character and amount of work needed on same and all else necessary to make same a good and acceptable highway. The road commissioner, or engineer if there be one, shall then prepare detailed plans and specifications for the construction or reconstruction or working of same by contract, which shall be presented to the board of supervisors for approval. The plans and specifications shall be filed with the clerk of the board of supervisors for the inspection of prospective bidders, prior to the first public letting under the terms hereof at a regular meeting to be named; and at any time prior to the acceptance of bids, the board may alter the plans and specifications submitted, and thereupon readvertise.