(1) An unobstructed aisle not less than three feet wide must be maintained for travel of the operator except in such cases where the control handles are hung from the trolleys of traveling cranes.
(2) The controller or controllers, if rope operated, must automatically return to the "off" position when released by the operator.
(3) Pushbuttons in pendant stations must be returned to the "off" position when pressure is released by the crane operator.
(4) All pushbuttons must be marked to indicate their purpose.