If any clause, sentence, paragraph, section or part of this USDO shall be adjudged by any court of competent jurisdiction to be invalid, such judgment shall not affect, impair, or invalidate the remainder thereof but shall be confined in its operation to the clause, sentence, paragraph, section or part thereof directly involved in the controversy in which such judgment shall have been rendered. Without affecting this general statement, each section of the sign regulations in § 375-409 (Signs) are specifically severable, and the invalidity of any regulation in that section shall not affect the validity or enforceability of other regulations in that section.