No person shall trench or otherwise excavate or place any building materials, rubbish, brick, earth, gravel, sand or similar materials upon any street, alley, sidewalk, crosswalk or public place in the city, and there allow the same for 24 hours or longer, unless he shall substantially fence the same with a barrier of boards, planks or railings to prevent accident or injury to persons and property; and it shall be the duty of the person so occupying or obstructing any street, alley, sidewalk, crosswalk or public place, to cause one or more red lights to be securely and conspicuously posted at or on that excavation, stationing one of those lights at each end of the space so occupied.  Where the excavation or obstruction exceeds 25 feet in either length or breadth, that person shall place additional lights at intervals of not less than 50 feet.  That person shall maintain and continue the burning of those lights from dusk until daylight during every night that the excavation or obstruction shall be allowed so to remain.  No person shall take down, remove or extinguish any signal or red light so placed by that person during the hours of the night.
('71 Code, § 100.12)  Penalty, see § 97.999