The railroads subject to national supervision shall be laid out and equipped in accordance with uniform standards established by the Commonwealth. They shall be maintained in safe operating condition and developed according to the requirements of traffic. Facilities and equipment for passenger and freight traffic shall be maintained and developed in keeping with the demand. The supervision of rates is designed to secure non-discriminatory and moderate railroad charges. ARTICLE 96 All railroads, including those not serving as means of general public communication, must comply with the requirements of the Commonwealth so far as concerns the use of the roads for purposes of national defense. ARTICLE 97 It is the duty of the Commonwealth to acquire ownership of and to operate all waterways serving as means of general public communication. After they have been taken over, waterways serving as means of general public communication may be constructed or extended only by the Commonwealth or with its consent. In the administration, development, or construction of such waterways the requirements of agriculture and water-supply shall be protected in agreement with the States. Their improvement shall also be considered. Each waterways administration shall consent to connection with other inland waterways at the expense of the latter. The same obligation exists for the construction of a connection between inland waterways and railroads. In taking over the waterways the Commonwealth acquires the right of expropriation, control of rates, and the police power over waterways and navigation. The duties of the river improvement associations in relation to the development of natural waterways in the Rhine, Weser, and Elbe basins shall be assumed by the Commonwealth. ARTICLE 98 Advisory national waterways councils will be formed in accordance with detailed regulations issued by the National Cabinet with the consent of the National Council to co-operate in the management of the waterways. ARTICLE 99 Charges may be imposed on natural waterways only for such works, facilities, and other accommodations as are designed for the relief of traffic. In the case of state and municipal public works they may not exceed the necessary costs of construction and maintenance. The construction and maintenance costs of works designed not exclusively for the relief of traffic, but also for serving other purposes, may be defrayed only to a proportionate extent by navigation tolls. Interest and amortization charges on the invested capital are included in the costs of construction. The provisions of the preceding paragraph apply to the charges imposed for artificial waterways and for accommodations in connection therewith and in harbors.