Whenever any ordinance designates and describes a through street, there shall be a stop sign on each and every street intersecting such through streets or intersecting portion thereof described and designated as such by any ordinance unless traffic at any such intersection is controlled at all times by traffic-control signals.  However, at the intersection of two such through streets or at the intersection of a through street and a heavy traffic street not so designated, or at the intersection of two other streets neither of which is designated a through street, stop signs shall be erected at the approaches of either of such streets.
('84 Code, § 16-35)