In R9 or R10 Districts when the air space above a street or portion thereof is closed, demapped and conveyed by the City to the owner of an adjoining zoning lot owned by a non-profit institution pursuant to State-enabling legislation enacted in 1971, the City Planning Commission may, by special permit, allow in such demapped air space, the development or enlargement of buildings which are an expansion of an existing hospital, college, university or functionally-related facility. In connection therewith, the Commission may also permit modification of off-street loading and bulk regulations, except floor area ratio regulations, under the applicable district regulation, provided that the requirements set forth in the 1973 Agreement among the City of New York, the Society of the New York Hospital, and the New York Society for the Relief of the Ruptured and Crippled, maintaining the Hospital for Special Surgery and the Rockefeller University are met; and that such demapped air space shall be considered as part of the adjoining zoning lot, except that any building located in demapped air space shall utilize only unused floor area from the portion of the adjoining zoning lot not within the demapped air space.

In order to grant such special permit, the Commission shall find:

(a)        for development or enlargements in such demapped air space and for modification of bulk regulations, that the location and distribution of new bulk shall result in a good site plan in relation to the existing buildings on-site and in the area; and

(b)        for modification of off-street loading requirements, when such non-profit institution includes more than one building on two or more zoning lots, the Commission may determine the required number of loading berths as if such non-profit institution were located on a single zoning lot, and may permit such loading berths to be located anywhere within such institution without regard for zoning lot lines, provided that such loading berths shall be:

(1)        adequate to serve the requirements of the institution;

(2)        accessible to all the uses in such institution without the need to cross any street at grade; and

(3)        located so as not to adversely affect the movement of pedestrians or vehicles on the streets within or surrounding such institution.

The curb level of a zoning lot of which the demapped air space is a part shall not be affected by the closing and demapping of air space above such street. However, the Commission may establish an appropriate level or levels instead of curb level as the reference plane for the applicable regulations relating to open space, yards, level of yards, equivalent rear yards, rear yard setback, minimum distance between buildings, and the front height and setback.

The Commission may impose additional conditions and safeguards, consistent with the requirements set forth in the 1973 Agreement, to improve the quality of the development and minimize adverse effects on the character of the surrounding area.