(1)When a street or portion thereof will be diverted, widened, altered or interfered with, or a new street will be made, under this Act, the Authorities may enter into and carry into effect agreements with the highway authority in reference to the construction or contribution towards the costs of such diversion, widening or alteration or of any such new street and in reference to any other matters relating thereto.
(2)The Authorities may by agreement delegate to the highway authority the power of constructing and maintaining all or any of such diversions, widenings, alterations or new street in which they may be interested.