All openings, obstructions or places where the sidewalk is removed shall be carefully guarded, protected or barricaded at all times. During the night season such sites shall be defined by red or amber colored lights or other lights approved by the Director of Public Service and such other precautions shall be taken as are necessary to guard against accidents. In this respect, the Director may issue any additional orders as he may deem proper. Such orders shall be complied with implicitly and promptly. At all times the work shall be done so as to cause the least inconvenience to property owners and the general public.