(1) From the negligence of any of the officers, agents, or employees of the carrier;
(2) By reason of any insufficiency of clearance of obstructions; of strength of roadbed and tracks or structures, or machinery and equipment; of lights and signals in switching and terminal yards, or rules and regulations; and of number of employees to perform the particular duties with safety to themselves and their coemployees, or of any other insufficiency; or
(3) By reason of any defect, which defect is due to its negligence in its cars, engines, motors, appliances, machinery, tracks, roadbeds, boats, works, wharves, or other equipment.