No member of the Department, or any person in the employ of the Department, no county commissioner, county engineer, road superintendent, or any person in their employ, or one holding an appointment under them, shall be either directly or indirectly interested in any contract for the construction or building of any bridge or culvert, or of any improvement of any road or parts of road coming under the provisions of this Code.
Okla. Stat. tit. 69, § 630