[With regard to any county which is exempt from the provisions of Section 19-2-3, this section shall read as follows:]
It shall be the duty of all road overseers and road commissioners whose road is affected by the order of the board of supervisors provided by Sections 65-7-43 through 65-7-47 to see that a notice thereof is posted at conspicuous places on such road at intervals of not less than two (2) miles and at the approaches to any bridge affected thereby; but a failure to post such notice shall not be allowed as a defense to a criminal prosecution or civil suit under the provisions of this chapter.