SECTION 1.  Section 17 of Chapter 90 of the General Laws, as appearing in the 2006 Official Edition, is hereby amended by deleting the word "thirty" in the second sentence and inserting in place thereof the following words:- “twenty five”.

SECTION 2. Section 18 of said Chapter 90 of the General Laws, as so appearing, is hereby amended by inserting after the first paragraph the following new paragraph:-

"Notwithstanding the foregoing, upon a vote by the city council, the transportation commission of the City of Boston, the board of selectmen or town council as the case may be, a city or town may make special regulations as to the speed of motor vehicles on functionally classified local ways; provided however, that the way in question is wholly contained in the municipality; provided, further, that a professional engineer in civil or traffic engineering registered within the Commonwealth and the chief of police or the board or officer having control of the police in a city or town first certify in writing that such regulation is consistent with the public interest and public safety; provided further, that such regulations shall not be subject to the approval of the department of the registrar. For the purpose of this paragraph, a functionally classified local way shall be a public way in a residential area and a public way between a residential area and a minor commercial area."