Such city shall also have power to enter into agreements with any individual, copartnership, association, or corporation, having any structure or appliance located under, on, or above the highways of said city, or intending to construct the same, either prior to, during, or subsequent to the construction of such tube, tunnel, or subway, for the location or relocation of such structures and appliances in such tube, tunnel, or subway. All such agreements shall be subject to the approval of the Public Service Commission.