Any person, firm, corporation, association or other making any excavation of tunnel shall do so according to the terms and conditions of the application and permit authorizing the work to be done. Sufficient and proper barricades and lights shall be maintained to protect persons and property form injury by or because of the excavations being made. If any sidewalk is blocked by any such work a temporary sidewalk shall be constructed and provided which shall be safe for travel and convenient for users. (Ord. #316, Section V, 05/19/59).