Abstract: Employee #1 and a coworker were each standing on 2 in. by 10 in. by 8 ft wooden boards between two girders on a bridge. The coworker was on the south board, Employee #1 was on the north board, and another coworker was atop the second girder. They were placing a diagonal brace between the two girders and needed to spread them another 1/2 in. The first coworker was holding a 4 by 4 by 7 ft 8 1/2 in. piece of wood and operating the bottle jack to move the two girders away from one another. Employee #1 installed the bolt and was putting the nut on the diagonal piece when the bottle jack and 4 by 4 apparently shot out toward him. The second coworker took hold of the 4 by 4, but apparently the jack knocked Employee #1 backward off the board. He fell into some wires that run above the RTA tracks, landing between the two tracks. He was killed.