Massachusetts General Laws Part I. Administration of the Government (Ch. 1-182) Ch. 89, § 6A

Every motorman of a car upon a street railway shall, upon the approach of any fire apparatus going to a fire or responding to an alarm, immediately stop said car and keep the same at a standstill until such apparatus has passed. Violation of any provision of this section shall be punished by a fine of not more than twenty-five dollars.