Abstract: A supervisor and three other employees were performing maintenance work at an entertainment park. They were working on the laminated wood track of a roller coaster named "Ghost Rider." The supervisor directed the three other employees to remove and replace track steel (that is, running track steel and guide steel) on the wooden roller coaster structure. The supervisor and one of the other employees were working from the catwalk, approximately 7.3 meters above the ground. They had placed 19-millimeter-thick wood planks (measuring 1.2 by 0.6 meters) on top of the 2.4-meter-long, 100- by 100-millimeter crossties between the two laminated wood roller coaster track supports, which were 0.8 meters apart. The wooden planks were placed in one section of the track, and the supervisor, who was not using personal fall protection equipment, walked over to another section to expedite the work. (No planks were placed at this section of track.) He stepped onto the crossties to begin removing bolts from the guide steel. The supervisor lost his balance and slipped when he stepped onto the crossties. He fell to the ground. He was hospitalized with fractures of his left arm, right leg, and vertebrae. He also suffered some broken teeth.