EE WAS INVOLVED IN MOVING RAIL CARS FOR UN-LOADING. CO-WORKER WAS OPERATING THE TRACK-MOBILE. WHEN THEY APPROACHED THE SWITCH, EE WAS STANDING ON BOTTOM RUNG OF TRACK MOBILE LADDER AND LOST HI S BALANCE. EE WAS SLOWING THE TRACK MOBILE TO STOP IT, BUT EE WAS ATTEMPTING TO PUSH HIMSELF AWAY FROM LADDER (LOST BALANCE) AND MOMENTUM OF STOPPING CAUSED EE TO SWING AROUND IN FRONT OF WHE