Mass. Gen. Laws ch. 161 § 94
Whoever wilfully obstructs a company or the Metropolitan Transit Authority in the legal use of a railway track, or delays the passing of its cars thereon, or wilfully obstructs a company or the Metropolitan Transit Authority in the legal use of a public way by a trackless trolley vehicle, or delays the passing of its trackless trolley vehicles thereon, or aids or abets in such obstruction or delay, shall be punished by a fine of not more than five hundred dollars or by imprisonment for not more than three months. Whoever commits any of said acts in such a manner as to endanger the life or safety of persons conveyed in or upon said cars, or trackless trolley vehicles, or aids or abets therein, shall be punished by a fine of not more than one thousand dollars or by imprisonment in the state prison for not more than ten years.
Mass. Gen. Laws ch. 161, § 94