It shall be unlawful to obstruct the crossing, or any portion of the width thereof, of any street in the city by any railroad engine, car or cars of any description for a longer time than five consecutive minutes, and whenever either of such crossings shall have been obstructed, or any portion of its width, by any such engine, car or cars for more than five consecutive minutes at any one time, it shall be left entirely free and unobstructed for at least five consecutive minutes, except that this section shall not apply to any through train passing over such crossings and kept in constant forward motion while passing the crossings.
(Code 1943, Art. 49-7)