Sec. 8.
That it shall be the duty of the board, in coöperation with the Secretary of War, with the object of promoting, encouraging, and developing ports and transportation facilities in connection with water commerce over which it has jurisdiction, to investigate territorial regions and zones tributary to such ports, taking into consideration the economies of transportation by rail, water and highway and the natural direction of the flow of commerce; to investigate the causes of the congestion of commerce at ports and the remedies applicable thereto; to investigate the subject of water terminals, including the necessary docks, warehouses, apparatus, equipment, and appliances in connection therewith, with a view to devising and suggesting the types most appropriate for different locations and for the most expeditious and economical transfer or interchange of passengers or property between carriers by water and carriers by rail; to advise with communities regarding the appropriate location and plan of construction of wharves, piers, and water terminals; to investigate the practicability and advantages of harbor, river, and port improvements in connection with foreign and coastwise trade; and to investigate any other matter that may tend to promote and encourage the use by vessels of ports adequate to care for the freight which would naturally pass through such ports: Provided, That if after such investigation the board shall be of the opinion that rates, charges, rules, or regulations of common carriers by rail subject to the jurisdiction of the Interstate Commerce Commission are detrimental to the declared object of this section, or that new rates, charges, rules, or regulations, new or additional port terminal facilities, or affirmative action on the part of such common carriers by rail is necessary to promote the objects of this section, the board may submit its findings to the Interstate Commerce Commission for such action as such commission may consider proper under existing law.