The Commission shall have the power, whenever they deem it for the public good, to designate, establish and, from time to time, alter building and veranda lines, or either, on the land of proprietors adjoining any highway within the Town between which line and such highway no building or part of a building shall thereafter be set up or erected, provided the aggregate damages payable in consequence of the establishment or alteration of a building or veranda line under the provisions hereof shall not exceed the aggregate special benefits assessed hereunder upon the property benefited thereby.