It shall be the duty of the policemen to be vigilant in the enforcement of the provisions of this Chapter, and report any violation thereof to the Marshal. Every policeman shall, on observing or being informed of the opening of or excavating in any street or avenue, require the person making such opening or excavation to exhibit to him the authority or permission for such opening; and if none has been given by the proper officer or the exhibition thereof be refused, said Marshal shall, without delay, report the same to the Engineer.