“Terminal facilities” means all land, buildings, structures, improvements, equipment and appliances useful in the operation of public warehouse, storage and transportation facilities for the accommodation of or in connection with commerce by water or land or in the air or useful as an aid, or constituting an advantage or convenience to, the safe landing, taking off and navigation of aircraft, or the safe and efficient operation or maintenance of a public airport; except that nothing in this definition contained shall be interpreted as granting authority to the District to acquire, purchase, create, erect or construct a bridge across any waterway which serves as a boundary between the State of Illinois and any other state.