Section 81J. A city or town which has a planning board under section eighty-one A may establish, in the manner provided for the laying out of city or town ways, the exterior lines of any way, the location of which has been approved under section eighty-one G or the subdivision control law; and thereafter no structure shall be erected or maintained between the exterior lines so established, except that buildings or parts of buildings existing at the time of the establishment of said lines may remain and be maintained to such extent and under such conditions as may be prescribed by such planning board. Lines established under this section may be discontinued in the manner provided for the discontinuance of a highway or a city or town way. Lines so established shall be placed on the official map, if any, of the city or town, without further action by the city council or town meeting, and shall be removed therefrom if discontinued. Any person injured in his property by the establishment of exterior lines under this section may recover damages so caused under chapter seventy-nine.