Any such city may grant the exclusive right to purchase an existing bridge or to construct a new bridge, and to maintain any such bridge within a distance not exceeding one mile on each side of the bridge to be so purchased or constructed, for the period necessary to reimburse cost plus not exceeding eight percent thereof for financing charges, together with interest upon said cost and charges, but in no event to exceed ten years, subject to the condition that at the termination of such period, such bridge shall become the sole property of the public and thereafter be maintained and operated by the city as a toll or free bridge as such city may determine from time to time in harmony with the other provisions of sections 14-1201 to 14-1252 and the laws of the United States. Such grant shall be made in the same manner and subject to the same conditions as may be provided in the charter of such city for the granting of franchises. Any such grant or assignment shall by operation of law be subject to the following conditions: The number of officers and employees and the salaries, wages, and compensation thereof shall be reasonable; no person shall be permitted free use of the bridge or use at discriminatory toll; tolls shall be both adequate to hasten payment for the bridge and reasonable to the public; financing costs shall be reasonable and the city may impose requirements and safeguards as to the conservation of funds and insurance of property; complete statements of operations and finances shall be filed with the city clerk on bond interest dates upon completion of the bridge and upon delivery of same to the city; and the city shall have power to require or itself perform audits and examine the books and call for any reports at any time. The city may enforce these obligations in any court of competent jurisdiction. Any such assignment shall by operation of law be subject to the conditions that the plans and specifications, the location, size, type and method of construction, the boundaries and approaches and the estimates of cost of construction and acquisition shall be first submitted to the governing body of the city and receive its approval before any construction shall be commenced or any contract for construction or for financing construction shall be entered into.