In Subdistrict A, as shown on Map 1 in the Appendix to this Chapter, the underlying height and setback provisions are modified by the provisions of this Section.

1. Street wall location
   1. Along the elevated rail structure
      
      For street walls, or portions thereof, within 100 feet of street lines along the elevated rail structure on Jerome or River Avenues, the street wall location provisions of paragraph (a)(1) of Section 35-643 (Special provisions in other geographies) shall apply.
   2. Along designated streets
      
      In Subareas A1 through A3, along the streets designated on Maps 2 through 4 in the Appendix to this Chapter, the following shall apply:
      1. In Commercial Districts
         
         In Commercial Districts, the street wall location provisions of paragraph (b) of Section 35-631 shall apply, except that the street wall shall extend to at least a height of 30 feet, or the height of the building, whichever is lower. In addition, above a height of 30 feet, at least 50 percent of the aggregate width of street walls shall be located within eight feet of the street line and shall extend to at least a minimum base height of 60 feet, or the height of the building, whichever is lower.
         
         The remaining aggregate width of street walls may be recessed beyond 15 feet of the street line, provided that any such recesses deeper than 10 feet along a wide street or 15 feet along a narrow street are located within an outer court.
         
         In the corner locations designated on Maps 2 and 3, an open space may be provided within 75 feet of the corner, pursuant to the provisions of paragraph (b) of Section 141-33.
      2. In Residence Districts
         
         For street walls, or portions thereof, located in Residence Districts, at least 70 percent of the aggregate width of street walls shall be located within 15 feet of the street line and shall extend to at least the minimum base height set forth in paragraph (b) of this Section, or the height of the building, whichever is lower.
         
         The remaining aggregate width of street walls may be recessed beyond 15 feet of the street line, provided that any such recesses deeper than 10 feet along a wide street or 15 feet along a narrow street are located within an outer court.
         
         The underlying allowances for street wall articulation, set forth in paragraph (d) of Section 23-431 shall be permitted to project or recess, where applicable, beyond the street wall locations established in this paragraph.
         
         In the corner locations designated on Map 4, an open space may be provided within 75 feet of the corner, pursuant to the provisions of paragraph (b) of Section 141-33.
   3. Along other streets
      
      In Subareas A1 through A3, along streets that are not designated on Maps 2 through 4, and in Subarea A4, along all streets, no street wall location provisions shall apply, and no minimum base heights shall apply.
2. Base heights and maximum building heights
   
   The underlying height and setback regulations shall apply, except as modified below:
   1. for street walls facing the elevated rail structure, beyond 75 feet of the corner of streets intersecting Jerome or River Avenues, the maximum base height shall be 30 feet;
   2. the setback provisions of Section 23-433 (Standard setback regulations) shall apply except that for portions of buildings or other structures along Cromwell Avenue located beyond 200 feet from a corner, a minimum setback with a depth of at least 30 feet shall be provided;
   3. In R9A Districts, or in Commercial Districts mapped within R9A Districts:
      1. the maximum base height shall be 125 feet;
      2. above the required setback, the height of a building shall not exceed a maximum transition height of 175 feet;
      3. where the lot coverage of all buildings on the zoning lot above the maximum transition height has been reduced to 50 percent on zoning lots with a lot area less than or equal to 15,000 square feet, 40 percent on zoning lots with a lot area greater than 15,000 square feet but less than 30,000 square feet, and 30 percent for all other zoning lots, a building may rise to a maximum building height of 225 feet. The maximum street wall width of any story above the maximum transition height shall not exceed 165 feet and, where two or more non-contiguous portions of a building exist at the same level above the maximum transition height, such portions shall provide a minimum distance of 60 feet between facing walls at any point.
3. Required and permitted articulation
   
   In Subareas A1 through A3, along streets designated in Maps 2, 3 and 4 in the Appendix to this Chapter, for street wall widths exceeding 100 feet, a minimum of 20 percent of the surface area of street walls above the level of the second story, or a height of 30 feet, whichever is lower, shall either recess or project a minimum of three feet from the remaining surface of the street wall. Any such projections shall be considered a permitted obstruction into a required setback, provided that any projections with a depth greater than five feet shall be considered a dormer.
   
   In addition, the underlying dormer provisions of paragraph (b) of Section 23-413 (Permitted obstructions in certain districts) shall apply, except that in Subareas A1 through A3, for street walls intersecting within 100 feet of the corners designated on Maps 2, 3 and 4, and irrespective of the width of the street wall below the maximum base height, dormers shall be permitted within 100 feet of such intersecting street walls. Such dormers need not decrease in width as the height above the maximum base height increases.
   
   Any dormers or projections provided in accordance with this paragraph need not be included in the maximum lot coverage permitted above the maximum transition height, nor be included in the maximum street wall width of a story.