OPERATOR WAS EXITING PARKING LOT ONTO MAIN ROAD WHEN VEHICLE PICKED UP SPEED, OPERATOR TRIED TO STOP VEHICLE, BY BREAKING, BUT VEHICLE ACCELERATED FASTER, CAUSING OPERATOR TO LOSE CONTROL OF VEHICLE , VEHICLE STILL ACCELERATING TURNED BACK TOWARDS OTHER END OF PARKING LOT CRASHING INTO LARGE METAL SIGN POST. OPERATOR HAD TO BE TAKEN TO NEARBY HOSPITAL, AND THEM EVACUATED TO MASS GENERAL HOSPITAL, FOR EMERGENCY HEAD OPERATION AS A RESULT OF INJURY TO HEAD. (SUBDURAL HEMOTOMA). *TR