Abstract: Employee #1 was en route from the shop to the work area, driving a 2 ton truck equipped with a boom ladder to change elevated lights. When he attempted to drive up a hill with an approximately 25 degree slope, the drive shaft twisted up and the truck would not move. Employee #1 engaged the parking brake, placed a light fixture ballast behind the right front wheel, and found a small rock to place under the left rear wheel. He then lay down under the truck and started to remove the rear universal joint. When the drive shaft was loose, the truck rolled backward and ran over Employee #1's chest. He suffered a fractured back and ribs, and was hospitalized.