Whenever any ordinance or resolution of this City designates and describes any street or portion thereof as a secondary arterial or any intersection at which vehicles are required to yield at one or more entrances thereto, the City Traffic Engineer shall erect and maintain yield signs as follows:

A yield sign shall be erected on every street intersecting such secondary arterial, or portion thereof so designated, at those entrances or other intersections where a yield sign is required. Every such sign shall conform to and shall be placed as provided in Section 21356 of the State Vehicle Code.