... in heavy or fast service, however, the arrangement in the picture below shows the station throat at Atlanta in the pre civil war era, so they were still in use on busy locations into the 1860s. The back to back arrangement of the two turnouts effectively creates a double slip, but, if I understand the arrangement correctly, it would apparently require the switchman to bend four lengths of rail into alignment in three possible positions, which presumably required a pretty brawny switchman! The gauge in this location is 5'. 2854_121416_430000000.jpg I think I understand the issue about needing clearances greater than that for a check rail, but this then raises the question of how you keep the moving approach rails square to the diverging rails. Surely, as soon as you swing the approach rails away from dead centre, the outer one will always become fractionally short and the inner one fractionally long. The Ffestiniog 4 way must be an extreme example of this, since it seems to be set up almost like a sector plate. Or am I overthinking this? Incidentally ...