An employee was descending the ramp in shop #3 when the fork truck began to accelerate. The employee attempted to slow it down by pulling the throttle pedal. The fork truck continued picking up speed because the throttle pedal was stuck so the employee attempted to pull the key out of the ignition to slow it down. The employee clipped the guardrail while trying to unstick the throttle catching his foot between the fork truck and a 6-inch railing resulting in a compound fracture of the left leg and a dislocated ankle with a hematoma.