The City Planning Commission may authorize a modification of any required minimum amount of pedestrian circulation space to be provided on wide street frontages and design standards, as indicated, for the following required pedestrian circulation spaces, to be provided within or under an existing building to remain on a zoning lot:

(a)        Arcade: minimum width, minimum height, obstructions, minimum clear width between obstructions, minimum length, column sizes

(b)        Building entrance recess area: minimum length, minimum depth from street line, minimum height, obstructions, clear space between obstructions and clear space between obstructions and building wall

(c)        Corner arcade or corner circulation space: minimum depth, minimum width of clear path, minimum height, obstructions

(d)        Through block connection: minimum width of unobstructed path, minimum height, through block level.

The Commission may authorize a modification of design standards for pedestrian circulation spaces when the following findings are met:

(1)        a modification is needed because of the inherent constraints of the existing building;

(2)        the modification is limited to the minimum needed because of the inherent constraints of the existing building; and

(3)        the pedestrian circulation space as modified shall be equal in area, and substantially equivalent, to the required space in terms of quality, effectiveness and suitability for public use.