Section 18. The city council, the transportation commission of the city of Boston, the board of selectmen, park commissioners, a traffic commission or traffic director, or the department, on ways within their control, may make special regulations as to the speed of motor vehicles and may prohibit the use of such vehicles altogether on such ways; provided, however, that except in the case of a speed regulation no such special regulation shall be effective unless it shall have been published in one or more newspapers, if there be any, published in the town in which the way is situated, otherwise in one or more newspapers published in the county in which the town is situated; nor until after the department, and in the case of a speed regulation the department and the registrar, acting jointly, shall have certified in writing that such regulation is consistent with the public interests; provided, however, that nothing herein contained shall be construed as affecting the right of the metropolitan district commission or of the department of environmental management to make rules and regulations governing the use and operation of motor vehicles on lands, roadways and parkways under its care and control. No such rule or regulation shall prohibit the use of passenger or station wagon type motor vehicles whose gross weight is less than five thousand pounds and which are registered for commercial use on ways where noncommercial passenger type motor vehicles are permitted to operate. No such regulation shall be effective until there shall have been erected, upon the ways affected thereby and at such points as the department and the registrar, acting jointly, may designate, signs, conforming to standards adopted by the department, setting forth the speed or other restrictions established by the regulation, and then only during the time such signs are in place. Any sign, purporting to establish a speed limit, which has not been erected in accordance with the foregoing provisions may be removed by or under the direction of the department.

Any person, corporation, firm or trust owning a private parking area or owning land on or abutting a private way, or any person, corporation, firm or trust controlling such land or parking area, with the written consent of the owner, may apply in writing to the city council, the traffic commission of a city or town having a traffic commission, the transportation commission of the city of Boston or the board of selectmen in any town in which the private way or parking area lies, to make special regulations as to the speed of motor vehicles and as to the use of such vehicles upon the particular private way or parking area, and the city council with the approval of the mayor, the traffic commission of a city or town, the transportation commission of the city of Boston or the board of selectmen, as the case may be, may make such special regulations with respect to said private way or parking area to the same extent as to ways within their control and such special regulations shall not be subject to approval by the department or the registrar; provided, however, that any traffic signs, signals, markings or devices used to implement such special regulations shall conform in size, shape and color to the most current manual on uniform traffic control devices.