The permittee shall take appropriate measures to assure that during the performance of the excavation work traffic conditions as nearly normal as practicable shall be maintained at all times so as to cause as little inconvenience as possible to the occupants of the abutting property and to the general public; provided that the administrative authority may permit the closing of streets to all traffic for a period of time prescribed by him if in his opinion it is necessary. (Ord. 119 § 1(1009), 1969).