All excavations shall be properly protected by barricades, danger warning signs, and during the night season by proper flares or red warning lights. It shall be one of the conditions of the permit and the duty of the contractor to maintain these warning signs and lights at all times that the excavation is open or as hereinbefore specified. In the event that it is necessary to excavate across the entire width of any street or highway, only 1/2 of the street or highway must be excavated at one time and the same shall be properly restored for the safe passage of vehicular traffic before the remaining 1/2 of the street is excavated. In the event of the above, it shall be one of the conditions of the permit and the duty of the contractor to maintain proper safety facilities to safely regulate both pedestrian and vehicular traffic at the site, which procedure must be approved by the public works department and the police department. In the event of an emergency when it shall be necessary to close the entire street or highway, the department of public works, the police department and the fire department shall be notified at once of the action to close the street or highway.
('66 Code, § 22-6)