No curb cuts shall be permitted on commercial streets as shown on Map 2 in the Appendix to this Chapter. However, if access to a required accessory parking facility or loading berth is not possible because of such restriction, a curb cut may be allowed if the Chairperson of the City Planning Commission certifies to the Commissioner of Buildings that such location is the only possible location for the facility or loading berth, is not hazardous to traffic safety, is at least 50 feet from the intersection of two street lines, and is constructed so as to have minimal effect on the streetscape.