The said cities shall have the right to enact ordinances, providing for the laying-out and opening of the routes or locations for said viaducts and bridges, which shall be public highways; and the proceedings for the said laying-out and fixing the locations, and for the opening thereof, shall be the same as is provided by law in the laying-out and opening of streets in said cities, except that no petition of property owners shall be required therefor.
53 P.S. § 2502