When signs are placed, erected, or installed in each block giving notice thereof, no person shall park a vehicle between the hours of l:00 a.m. and 6:00 a.m., upon any of the streets designated on the official map, unless other hours are designated.  However, this section shall not apply to vehicles parked on the streets between the hours of 1:00 a.m. and 6:00 a.m. when the owners thereof are at work in the building or on the premises in front of or near which the vehicles are parked.
('72 Code, § 11-18)  Penalty, see § 74.99