Air rights, as usually defined, comprise the rights vested in the ownership of all the property at and above a certain horizontal plane as well as caisson and column lots essential to contain the structural supports of the air rights improvement. This means in effect a horizontal division of real property, with the parts under separate ownership and involving an allocation of responsibilities and rights. The utilization of air rights consists of construction \in space\, above an existing surface use. Thus, it encompasses more than the usual vertical arrangement of different uses, as may be found in an office building with stores on the ground floor, an apartment hotel having a garage in the basement, or a railway station on top of tracks. These typical building use arrangements include three characteristics that are lacking in most air rights development: single ownership, a functional kinship among the uses, and synchronized planning and construction.
