The obstructions set forth in Section 33-42, other than the rooftop equipment permitted pursuant to Section 104-321, as well as the following obstructions, may penetrate the applicable maximum building height and the applicable maximum height for rooftop equipment set forth in Appendix B of this Chapter, and may also penetrate the sky exposure plane set forth in Section 104-321 (Rooftop equipment). Within 50 feet of the upper street wall, the width of such obstructions shall be limited in total to 10 percent of the aggregate width of street walls of a building, per street frontage, at any level above the maximum level of rooftop equipment as set forth in Section 104-321. Beyond 50 feet from the upper street wall, the permitted obstructions may occupy an area not to exceed 30 percent of the building coverage at the ground level. Where portions of the upper street wall are located at different distances from the street line or mandatory widened sidewalk line, whichever is applicable, the portion used to establish such reference line shall be the portion that occupies the greatest area of such upper street wall. However, in no event shall such obstructions be located within 10 feet of the upper street wall.

(a)        Antennae and structural support thereto;

(b)        Pipes and supporting structures;

(c)        Railings.