In the event of an emergency in which it would be impossible for the county commission to employ an engineer, the commission shall employ a competent road supervisor who need not be an engineer, but, when so employed shall have, within the boundaries of applicable law, all the duties and authority of the county engineer and shall be subject to this article. The emergency employment of a competent road supervisor shall not continue longer than necessary to employ a qualified engineer who will accept employment by the commission under the terms of this article. It is the intention of this article to provide that the inspection, construction, and maintenance of county roads, bridges, and ferries shall be under the supervision of a qualified engineer.