(A) Those streets and parts of streets described in Traffic Schedule XXI, hereby made a part hereof, are declared to be through streets for the purpose of this subchapter.
('58 Code, § 16-24(a))
(B) Whenever any ordinance designates and describes a through street, there shall be a stop or yield right-of-way sign on each street intersecting the through street or intersecting a portion thereof described and designated as a through street by any ordinance, unless traffic at the intersection is controlled at all times by traffic-control signals. However, at the intersection of two 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, signs shall be erected at the approaches of either of the streets.