The width and location of sidewalks are established as follows: Upon all streets where sidewalks have already been constructed, the sidewalks shall be the same width as and conform to, as to location, other sidewalks on the same street with an absolute minimum width of four feet, unless otherwise ordered by the Director of Public Service and Safety; upon all streets having no sidewalks, the width and location of new sidewalks shall be fixed by the Director of Public Service and Safety. All sidewalks shall be constructed under the supervision and subject to the approval of the Director of Public Service and Safety. (1979 Code 93.26)