The method was designed to limit some of the problemsinherent with the open ended lifting.
It reduces the lenght of each lift so the a continuous miner and its crew are exposed to a lesser span of cantilevered roof. It is not so amenable to ad hoc changes to the extraction sequence and it requires less tramming time losses between successive lifts.
The goaf edge fenders can be up to 2m thick so that in fact the lifts are not open ended.
In many coals the fender width of 2 – 3m is insufficient to prevent failure when the adjacent goaf falls and may provide a false sense of security.
If the fenders are increased to a sufficiet thickness, then no longer is the system aimed at total extraction by “pocketing” the pillar as shown.