Whenever a formal vote or order for the laying out or construction of a public improvement, or for the taking of land therefor, states that betterments are to be assessed, no betterments shall be assessed except under this chapter or chapter eighty A, and all proceedings relating to such betterments shall be as herein or therein provided, notwithstanding any special act hitherto enacted.
Mass. Gen. Laws ch. 80, § 17