7. The commissioner of transportation and any city named in this article, acting through the mayor or other administrative head thereof, pursuant to a resolution of the governing body of such city except the city of New York, are authorized to enter into a written agreement for the maintenance and repair, under the supervision and subject to the approval of the commissioner, of any public street, main route or thoroughfare or portion thereof, exclusive of service roads and pavement on intersecting street bridges, which is within the boundaries of such city and which is now or which shall hereafter be designated in this article and which has been constructed or which shall have been constructed as authorized by articles four and twelve-B of this chapter and with grants made available by the federal government pursuant to the federal aid highway act of nineteen hundred forty-four, being public law five hundred twenty-one of the seventy-eighth congress, chapter six hundred twenty-six, second session, as approved on the twentieth day of December, nineteen hundred forty-four. Such agreement may provide that the state shall pay annually to such city a sum to be computed at the rate of (a) not more than eighty-five cents per square yard of the pavement area that is included in the state highway system according to the provisions of this section, and (b) an additional ten cents per square yard of such pavement area where such pavement area is located on any elevated bridge. The maintenance and repair, as provided in this section, shall be done either by the forces of such city and with its equipment, or by its contractor, or by a combination of these two methods.