Massachusetts General Laws Part I. Administration of the Government (Ch. 1-182) Ch. 159, § 27

The department may, either through its members or responsible agents, engineers, inspectors or examiners duly authorized by it, enter upon any premises occupied by any carrier subject to its jurisdiction for any purpose consistent with this chapter. It may inspect the property, equipment, buildings, plants, factories, power houses, ducts, conduits and offices of any such carrier. It may, in connection with such inspection, have performed for it such service of the kind rendered by the carrier as it may reasonably require, including passage upon any locomotive, car, vessel or vehicle while in service, and, upon reasonable notice, the use of an inspection locomotive, car, vessel or vehicle whenever that is necessary, in the opinion of the department, for a physical inspection of all or any of the lines and stations of any such carrier.