Any building or other structure fronting upon the north side of Surf Avenue shall not exceed a height of 85 feet. Furthermore, in order to protect the view from the elevated subway to the Coney East Subdistrict, no portion of such building or other structure, including permitted obstructions or signs, shall be located between a height of five feet below the upper level of the elevated subway tracks and a level 25 feet above such level, except for a vertical circulation core, supporting structural elements and related appurtenances. In no event shall more than 30 percent of the Surf Avenue frontage of the zoning lot be obstructed with such elements.