Except as herein provided, the regulations of this chapter shall not be so construed as to limit or interfere with the dedication, development or use of any land or building for public parks, playgrounds or public schools required for compulsory education or with the use of land or buildings owned by the United States government, the State of New York or any agency or municipality thereof, the County of Chautauqua or the City of Jamestown and used for governmental purposes or with the construction, installation, operation and maintenance for public utility purposes of water or gas mains or conduits, electric light or electric power transmission lines or distribution lines, or distribution facilities, telephone or telegraph lines, cable television lines, steam or district heating transmission lines, sewers, sewer mains or railroad rights-of-way existing or hereafter authorized by the City of Jamestown.