A.
The Board of Selectmen is hereby authorized, and as to those signs and signals required hereunder it shall be its duty, to place and maintain or cause to be placed and maintained all official traffic signs, signals, markings and safety zones. All signs, signals, markings and safety zones shall conform to the standards as prescribed by the Department of Public Works of the Commonwealth of Massachusetts.
B.
Sections 250-7 and 250-8 of Article II and §§ 250-36 through 250-40 relating to parking shall be effective only during such time as official signs are erected and maintained in each block designating the provision of such sections and located so as to be easily visible to approaching drivers. Sufficient number of such signs must be provided so that a car cannot be parked in a limited or prohibited parking place without having the legend side of such a sign, clearly setting forth the parking regulation thereat, visible from that location.