The commission is hereby authorized to prepare the necessary and proper plans and specifications for the construction of such bridges as may be designated by the governing body of the city, to select the location for same, determine the size, type and method of construction thereof, to plan and fix their boundaries and approaches, to make the necessary estimates of the probable cost of construction and the acquisition of the land and rights for the sites of the abutments and approaches and avenues or easements of access to the bridges in a manner hereinafter provided, to enter into the necessary contracts to build and equip the entire bridges and the approaches and avenues or easements of access thereto, to build the superstructures and substructures and all parts thereof, to obtain and exercise such consent or authority as may be necessary from the government of the United States and the approval of the Secretary of the Army and Chief of Engineers, and to cause a survey and map to be made of all lands, structures, rights-of-way, franchises, easements or other interests in lands, including lands under water and riparian rights owned by any persons, corporation or municipality, the acquisition of which may be deemed necessary for the construction of such bridges, and to cause such map and survey to be filed in its office. The members of the commission, or its agents and employees, may enter upon such lands and structures and upon lands under water notwithstanding any interests in such lands or structures, for the purpose of making such surveys and maps; PROVIDED, that the commission shall not proceed to exercise or carry out any authority or power herein given it to bind said commission beyond the extent to which money has been provided.