All contractors engaged in the construction or repairing of sidewalks must, during the time of construction or repairing and until such time as the walk is open for traffic, keep the same constantly enclosed by a woven wire fence of sufficient height and so constructed as to prevent persons or animals from crossing such walk, or walking on the same and must keep and maintain red lights burning thereon from sunset to sunrise and the engineer shall have control over the same and may at any time require additional enclosures to be placed around the same or the enclosures to be made more substantial and may require additional red lights to be placed thereon. (Ord. 97, 8-5-1910)