Any power granted by sections 14-1201 to 14-1252 to a city of the metropolitan class may be exercised by the city independently or in cooperation with or aid of similar action by any other city or any county in Nebraska, any city or county in an adjoining state, the State of Nebraska, any adjoining state, or the government of the United States, when such other political unit has been authorized by law to exercise the necessary powers. Such joint action may be directly by the city council through the medium of a joint bridge commission subject to the same conditions provided in such sections for independent action.