Mass. Gen. Laws ch. 160, § 133: Protection of employees; blocking of frogs, switches and guard rails

Section 133. The frogs, switches and guard rails, except guard rails on bridges, which are in or connected with the railroad tracks operated or used by any railroad corporation shall be kept so blocked by some method approved by the department as to prevent employees from being caught therein. A railroad corporation which violates this section shall be punished by a fine of not less than ten nor more than one hundred dollars.