Abstract: At approximately 11:39 a.m. on February 3, 2006, Employee #1 was clearing an existing trail into a roadway for a private homeowner. Having completed approximately four hours of brush clearing and road building work activity using a Caterpillar D-6 crawler, Employee #1 was exiting the wooded area. At this time an approximately 5-ft long by 0.5-in.-square boxed-tube pipe secured to the back of the operators cab screen became displaced and slid approximately 11 in. outside of the operators cab between the rear screen and a vertical upright member of the ROPS system. While the crawler was moving forward the boxed tube pipe struck a tree and was thrust into the back of Employee #1's head and knocked him unconscious. Employee #1 was transported to a local hospital by helicopter where he was hospitalized for two days with head injuries.